electro- and photocatalytic carbon dioxide reduction and

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Electro- and photocatalytic carbon dioxide reduction and thermal Electro- and photocatalytic carbon dioxide reduction and thermal

isomerization of highly strained tricyclocompounds isomerization of highly strained tricyclocompounds

Weiwei Yang

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ELECTRO- AND PHOTOCATALYTIC CARBON DIOXIDE REDUCTION AND THERMAL

ISOMERIZATION OF HIGHLY STRAINED TRICYCLOCOMPOUNDS

A Dissertation

presented in partial fulfillment of requirements for the degree of Doctor of Philosophy

in the Department of Chemistry and Biochemistry The University of Mississippi

by

WEIWEI YANG

August 2019

Copyright copy 2019 by Weiwei Yang ALL RIGHTS DESERVED

ii

ABSTRACT

Anthracene-bridged dinuclear rhenium complexes are reported for electrocatalytic and

photocatalytic carbon dioxide (CO2) reduction to carbon monoxide (CO) Related by hindered

rotation of each rhenium active site to either side of the anthracene bridge cis and trans

conformers have been isolated and characterized Electrochemical studies reveal distinct

mechanisms whereby the cis conformer operates via cooperative bimetallic CO2 activation and

conversion and the trans conformer reduces CO2 through well-established single-site and

bimolecular pathways analogous to Re(bpy)(CO)3Cl Higher turnover frequencies are observed

for the cis conformer (353 sminus1) relative to the trans conformer (229 sminus1) with both

outperforming Re(bpy)(CO)3Cl (111 sminus1) Photocatalytic reactivity shows the plausible pathway

for dinuclear system is one site acting as an efficient covalently-linked photosensitizer to the

second site performing CO2 reduction The excited-state kinetics and emission spectra reveal that

the anthracene backbone plays a more significant role beyond a simple structural unit

The isomerizations of 34-diazatricyclo[410027]hept-3-ene and 34

diazatricyclo[410027]heptane to their corresponding products were studied by ab initio

calculations at multiconfiguration self-consistent field level to study the stabilization effects from

π bond electrons and lone pair electrons The isomerization of 34-diazatricyclo[410027]hept-3-

ene occurs through four unique pathways The 122 kcal mol-1 disparity in the disrotatory barriers

is explained through π electron delocalization in the transition state The 34-

iii

diazatricyclo[410027]heptane structure has eight separate reaction channels for isomerization

Resonance stabilization from lone pair electron for two of the forbidden pathways results in a

relative energy lowering The isomerization of benzvalene to benzene has barriers of 206 kcal

mol-1 for the disrotatory channel and 268 kcal mol-1 for the conrotatory channel The

isomerization of benzvalene back to benzvalene occurs by the transition state disTSback with

barrier of 298 kcal mol-1 For the isomerization of benzvalyne the barriers are 229 kcal mol-1

for disrotatory channel and 217 kcal mol-1 for conrotatory channel Intrinsic reaction coordinate

shows the 1222 kcal mol-1 relative energy could be released only by 14 kcal mol-1 due to the

absence of normally intermediate with trans double bond

iv

LIST OF ABBREVIATIONS AND SYMBOLS

CO2 carbon dioxide

CO carbon monoxide

NHE normal hydrogen electrode

PTCE proton couple electron transfer

MOST molecular solar thermal system

DATCE 34-diazatricyclo[410027]hept-3-ene

DAP 3H-12-diazepine

DATCA 34-diazatricyclo[410027]heptane

DHDAP 23-dihydro-1H-12-diazepine

TATCE 345-triazatricyclo[410027]hept-3-ene

TAP 1H-123-triazepine

DMF NN-dimethylformamide

DMSO dimethyl sulfoxide

NMR nuclear magnetic resonance

ESI-MS electrospray ionization mass spectra

FTIR Fourier transformer infrared spectroscopy

CV cyclic voltammetry

CPE controlled potential electrolysis

v

GC gas chromatograph

FID flame ionization detector

TCD thermal conductivity detector

SEC spectroelectrochemical

DFT density functional theory

TS transition state

COSMO conductor-like screening model

Re2Cl2 18-di(22rsquo-bipyridine)anthracene(Re(CO)3Cl)2

anthryl-Re [1-(22rsquo-bipyridine)anthracene][Re(CO)3Cl]

Fc+0 ferroceniumferrocene

Epc cathodic peak potential

ipc cathodic peak current

ν scan rate

Bu4NPF6 tetrabutylammonium hexafluorophosphate

KC comproportionation constant

icat limiting catalytic current in the presence of CO2

ncat the number of electrons transferred in the catalytic process

F Faradayrsquos constant

A area of the electrode

vi

[cat] molar concentration of the catalyst

D diffusion coefficient

kcat rate constant of the catalytic reaction

[S] molar concentration of dissolved CO2

np the number of electrons transferred in the noncatalytic process

R ideal gas constant

T temperature

ip peak current observed for the catalyst in the absence of substrate

TOF turnover frequency

TON turnover number

FOWA foot-of-the-wave analysis

TFE 222-trifluoroethanol

MeOH methanol

PhOH phenol

Eappl applied potential

PS photosensitizer

BIH 13-dimethyl-2-phenyl-23-dihydro-1H-benzoimidazole

TEA triethylamine

φ quantum yield

vii

MLCT metal-to-ligand charge transfer

MCSCF multiple configuration self-consistent field

MRMP multireference Moller-Plesset

CCSD couple cluster single and double excitations

ZPE zero-point energy

NOON natural orbital occupation number

IRC intrinsic reaction coordinates

viii

ACKNOWLEDGEMENTS

There are so many people that I would like to express my sincere gratitude for their help

during my way to doctoral degree First I am very grateful to my advisors Prof Jonah W Jurss

and Prof Steven Davis for their support for my academic and research progress I have learned a

lot from Prof Jurss about fundamentals of scientific research during the first part of my graduate

schools time He always deeply inspired me by his hardworking and passion for scientific

research Especially I want to thank for his support and consideration when I decided to be more

involved in another research field The first time I really knew Prof Davis was in 2018 he taught

me physical chemistry class He is the most intelligent person I have ever met On the academic

level Prof Davis have built me up by advanced physical chemistry and quantum chemistry His

patience and motivation also lead me to the world of computational chemistry where I learned to

solve chemistry problems from calculation perspectives I could not imagine to successfully

complete my PhD study without those two respectful advisors Prof Jurss and Prof Davis

Besides my advisors I would like to thank the rest of my dissertation committee

members Prof Walter Cleland Prof Jared Delcamp and Prof Adam E Smith for their

insightful advice and great encouragement

ix

I would like to thank all my labmates and collaborators for their continue support I

could never finish my dissertation without their cooperation and contribution in various projects

Moreover I thank them for bring all the fun and joys into my graduate school

Last but not least I would like to deeply thank all my family and friends for their

encouragement and support whenever and wherever I feel discouraged while I pursue my

academic dream Especially I want to thank my husband Jiaxiang Zhang for his spiritually

supporting and endless love through my Ph D study and whole life I want to formally say thank

you to my son Geoffrey Zhang for the joys and happiness he brought to me He is also the person

make me feel more strong more capable and more confident

x

TABLE OF CONTENTS ABSTRACT ii

LIST OF ABBREVIATIONS AND SYMBOLS iv

ACKNOWLEDGEMENTS viii

LIST OF TABLES xiv

LIST OF FIGURES xv

INTRODUCTION 1

CHAPTER I ELECTROCATALYTIC CO2 REDUCTION WITH CIS AND TRANS

CONFORMERS OF A RIGID DINUCLEAR RHENIUM COMPLEX 7

11 Introduction 7

12 Experimental section 9

121 Materials and methods 9

122 Electrochemical measurement 9

123 X-ray crystallography 11

124 Computational methods 11

125 Synthetic procedures 13

13 Synthesis and characterization 16

14 Results and discussion 19

141 Electrochemistry 19

xi

142 Catalytic rates and faradaic efficiencies 26

143 UV-Vis spectroelectrochemistry 34

15 Conclusion 38

CHAPTER II PHOTOCHEMICAL CO2 REDUCTION WITH MONONUCLEAR AND

DINUCLEAR RHENIUM CATALYSTS BEARING A PENDANT ANTHRACENE

CHROMOPHORE 40

21 Introduction 40


221 Materials and characterization 44

222 Photocatalysis equipment and methods 45

223 Photophysical measurement equipment and methods 45

224 Photocatalysis procedure 46

225 Quantum yield measurements 47


231 Photophysical measurement 48

232 Photocatalysis 50

233 Quantum yield 54

24 Conclusion 55

xii

CHAPTER III ISOMERIZATION BARRIERS AND RESONANCE STABILIZATION FOR

THE CONROTATORY AND DISROTATORY ISOMERIZATIONS OF NITROGEN

CONTAINING TRYCYCLO MOIETIES 57

31 Introduction 57



331 34-Diazatricyclo[410027]hept-3-ene 63

332 34-Diazatricyclo[410027]heptane 74

333 Orbital stabilization 85


35 Conclusion 93

CHAPTER IV THE AB INITIO STUDY OF THERMAL ISOMERIZATION OF

BENZVALENE TO BENZENE AND BENZVALYNE TO BENZYNE 96

41 Introduction 96



431 Benzvalene 99

432 Benzvalyne 106

44 Conclusion 111

xiii

CONCLUSION 113

BIBLIOGRAPHY 115

APPENDIX A 139

APPENDIX B 187

APPENDIX C 195

APPENDIX D 217

VITA 226

xiv

LIST OF TABLES

Table 1 Electrochemical reduction of CO2 in the presence of a proton source (aqueous solution

pH 7 vs NHE) 2

Table 2 Reduction potentials diffusion coefficients and comproportionation constants (KC)

from cyclic voltammetry in anhydrous DMF01 M Bu4NPF6 solutions 21

Table 3 Summary of electrocatalysis obtained from cyclic voltammetry 30

Table 4 Summary of controlled potential electrolyses and Faradaic efficiencies for CO2

reduction under various conditions 31

Table 5 Activation barriers Ea for each pathway (kcal mol-1) Including ZPE correction 66

Table 6 Relative energies including ZPE correction 69

Table 7 Activation barriers Ea for each pathway (kcal mol-1) including ZPE correction 76







xv

LIST OF FIGURES

Figure 1 Schematic representation of conrotatory and disrotatory pathways 5

Figure 2 1H NMR spectra (500 MHz DMSO-d6) showing the aromatic region of A) cis-Re2Cl2

and B) trans-Re2Cl2 17

Figure 3 Crystal structure of trans-Re2Cl2 Hydrogen atoms are omitted for clarity Thermal

ellipsoids are shown at the 70 probability level 18

Figure 4 CVs of A) 2 mM Re(bpy)(CO)3Cl and anthryl-Re and B) 1 mM cis-Re2Cl2 and trans-

Re2Cl2 in DMF01 M Bu4NPF6 under Ar glassy carbon disc ν = 100 mVs 20

Figure 5 Cyclic voltammetry in Ar- and CO2-saturated DMF01 M Bu4NPF6 solutions with A)

1 mM cis-Re2Cl2 B) 1 mM trans-Re2Cl2 C) 2 mM Re(bpy)(CO)3Cl and D) 2 mM anthryl-

Re glassy carbon disc ν = 100 mVs The background under CO2 is shown with a dashed

blue line 22

Figure 6 CO2 concentration dependence for A) 1 mM cis-Re2Cl2 and B) 1 mM trans-Re2Cl2 in

DMF01 M Bu4NPF6 glassy carbon disc ν = 100 mVs Catalytic current (120583120583A) is plotted

versus the square root of [CO2] 23

Figure 7 Catalyst concentration dependence for A) cis-Re2Cl2 and B) trans-Re2Cl2 in CO2-

saturated DMF01 M Bu4NPF6 solutions glassy carbon disc ν = 100 mVs Linear fits with

slopes of 1 were obtained in log-log plots of catalytic current (120583120583A) versus catalyst

concentration (mM) 24

xvi

Figure 8 Cyclic voltammograms of A) 1 mM cis-Re2Cl2 B) 1 mM trans-Re2Cl2 C) 2 mM

Re(bpy)(CO)3Cl and D) 2 mM anthryl-Re with 3 M H2O in DMF01 M Bu4NPF6 under Ar

(black) and CO2 (red) glassy carbon disc 120584120584 = 100 mVs 29

Figure 9 FTIR spectra of A) trans-Re2Cl2 and B) cis-Re2Cl2 samples before and after

electrolysis Electrolyzed solutions are evaporated to dryness and washed with the

dichloromethane to remove the Bu4NPF6 electrolyte The resulting solid is analyzed 33

Figure 10 UV-Vis spectroelectrochemistry with A) 05 mM cis-Re2Cl2 at -17 V vs AgAgCl B)

05 mM trans-Re2Cl2 at -17 V vs AgAgCl C) 05 mM cis-Re2Cl2 at -20 V vs AgAgCl

D) 05 mM trans-Re2Cl2 at -20 V vs AgAgCl in Ar-saturated DMF01 M Bu4NPF6

solutions 34

Figure 11 Possible intermediates following reduction and chloride dissociation from cis-Re2Cl2

DFT optimized structures of a neutral dinuclear rhenium species and its one-electron

reduced radical anion 36

Figure 12 Proposed mechanism for cis-Re2Cl2 at Eappl = -20 V vs Fc+0 in DMF01 M Bu4NPF6

38

Figure 13 Key steps in potential pathways (1) and (2) with dinuclear rhenium catalysts

Analogous intramolecular electron transfer is expected with cis-Re2Cl2 in the PS pathway

(2) 41

Figure 14 Structures of Re photocatalysts studied for CO2 reduction 44

xvii

Figure 15 Transient absorption spectra at specified times after pulsed laser excitation (λex = 355

nm) of trans-Re2Cl2 in DMF under Ar purge (top) and trans-Re2Cl2 with BIH (001 M)

under CO2 purge (bottom) No reaction of the one-electron reduced trans-Re2Cl2 complex

with CO2 is evident in the first 800 micros following excitation 50

Figure 16 Left) TON vs catalyst concentration Middle) TOF vs catalyst concentration TOF is

fastest value measured within first two timepoints Right) TON for CO production vs time

for 01 mM cis-Re2Cl2 01 mM trans-Re2Cl2 02 mM anthryl-Re and 02 mM

Re(bpy)(CO)3Cl Conditions DMF containing 5 triethylamine 10 mM BIH irradiated

with a solar simulator (AM 15 filter 100 mWcm2) 52

Figure 17 Proposed catalytic cycle for photochemical CO2 reduction to CO with the dinuclear

Re catalysts cis-Re2Cl2 or trans-Re2Cl2 The trans conformer is shown in the specific

example above 55

Figure 18 Isomerization of tricyclo[410027]heptane to cyclohepta-13-diene and

tricyclo[410027]heptene to cyclohepta-135-triene 58

Figure 19 Isomerization of 3-aza-dihydrobenzvalene to 12-dihydropyridine 59

Figure 20 Isomerization of 3-aza-benzvalene to Pyridine 60

Figure 21 Structures of the Reactants DATCE DATCA and TATCE 61

Figure 22 Structures of 34-diazatricyclo[410027]hept-3-ene (DATCE) and isomerization

products 3H-12-diazepine (DAP1 and DAP2) 63

xviii

Figure 23 Schematic diagram for the isomerization of DATCE to DAP1 and DAP2 65

Figure 24 Transition state structures NconTS1 and CconTS1 for the two conrotatory pathways

66

Figure 25 Structures for the trans double bond intermediates NconInt and CconInt for the two

conrotatory pathways 67

Figure 26 Structures for the transition states for trans double bond rotation of NconInt and

CconInt to produce DAP2 70

Figure 27 Transition state structures NdisTS and CdisTS for the two disrotatory pathways 71

Figure 28 Intrinsic reaction coordinate plots for the DATCE to DAP1 and DAP2 isomerization

74

Figure 29 Structures of 34-diazatricyclo[410027]heptane (DATCA) and isomerization

products 23-dihydro-1H-12-diazepine (DHDAP1 and DHDAP2) 75

Figure 30 Schematic diagram for the isomerization of DATCA to DHDAP1 and DHDAP2 76

Figure 31 Structures of transition states CconTS1primeand CconTS1Prime 78

Figure 32 Structure of transition state NconTS1prime 80

Figure 33 Structures of NconTS1aPrime NconInt aPrimeand NconTS1bPrime 80

Figure 34 Densities for orbital 20 (p-type on C2 and C3) and orbital 27 (lone pair on N2) of

NconTS1Primeand NconIntaPrime 81

xix

Figure 35 Structures of transition states for the disrotatory channel of DATCA 84

Figure 36 Intrinsic reaction coordinates for the four conrotatory channels for DATCA

isomerization 85

Figure 37 Densities for orbital 19 (p-bonding on N1=N2) orbital 25 (p-type on C1 and C3) and

orbital 26 (p-type on C1 and C3) from the MCSCF natural orbitals for NdisTS1 87


orbital 26 (p-type on C1 and C3) from the MCSCF natural orbitals for NconTS1 88

Figure 39 Densities for orbitals 20 (lone pair on N2) 26 (p-type on C2 and C3) and 27 (p-type

on C2ndashC3) from the MCSCF natural orbitals for NdisTS1Prime 90

Figure 40 Structures of 345-triazatricyclo[410027]hept-3-ene (TATCE) and isomerization

products 1H-123-triazepine (TAP1 and TAP2 ) 91

Figure 41 Structures of the disrotatory transition states for the TATCE to TAP1 and TAP2

isomerizations 92

Figure 42 Structures of benzvalene and and isomerization product benzene 99

Figure 43 Schematic diagram for the isomerization of benzvalene to benzene and benzvalene

100

Figure 44 Transition state structures disTS and disTSback for the two disrotatory pathways 101

Figure 45 Reactions for the isomerization of benzvalene to benzene and benzvalene 103

xx

Figure 46 Structures for transition state conTS1a conTS1b and intermediate conInta for the

conrotatory pathway 105

Figure 47 Structures of benzvalyne and isomerization product benzyne 106

Figure 48 Schematic diagram for the isomerization of benzvalyne to benzyne 107

Figure 49 Transition state structure disTSprimefor the disrotatory pathway 108

Figure 50 Structures for transition state conTS1aprime conTS1bprimeand intermediate conIntaprimefor the


1

INTRODUCTION

Finding a sustainable energy conversion strategy is an urgent scientific and technological

challenge given our reliance on non-renewable fossil fuels as a primary energy source coupled

with increasing global energy demand1 Carbon dioxide is the chief component of this waste

stream which has been linked to climate change and other environmental concerns23 Renewable

energy sources such as wind and solar are attractive but they are intermittent site specific and

geographically diffuse Additionally they require energy storage before they can be relied on to

power society4 To address this challenge while reducing CO2 emissions solar energy or

renewable electricity can be used to drive the conversion of carbon dioxide and water into fuels

whereby energy is stored indefinitely in the form of chemical bonds for on-demand use The

efficient catalytic conversion of CO2 into energy-rich compounds could close the carbon cycle

and allow an underutilized resource to be tapped into5-11

Carbon dioxide is a non-polar linear and inert molecule The single-electron reduction

of carbon dioxide to radical ion CO2∙minus can be achieved by a significant amount of energy input

witnessed by a reduction potential of -190 V vs NHE in Table 112 The presence of proton

make carbon dioxide reduction feasible at lower energy cost by the use of proton couple electron

transfer (PCET) Additional concern existing in this process is the proton is utilized selectively

for carbon dioxide reduction rather than hydrogen generation since the proton reduction required

comparatively less negative potential of -042 V vs NHE in Table 1

2

Table 1 Electrochemical reduction of CO2 in the presence of a proton source (aqueous solution pH 7 vs NHE)

Molecular metal-based catalysts for CO2 reduction have been widely pursued as

transition metals generally have multiple redox states accessible to facilitate multi-electron

chemistry The bulk of these catalysts employ a single metal center5-11 Re(bpy)(CO)3Cl (where

bpy is 22-bipyridine) and related derivatives continue to attract attention as competent

electrocatalysts for CO2 reduction in addition to being single component photocatalysts13-27

Recently these systems have been functionalized with phosphonate anchoring groups for surface

attachment to photocathodes where they exhibit long-term stability for CO2 reduction28-33

Successful translation of these catalysts into working devices emboldens their continued

development where lower overpotentials and faster rates are remaining challenges

Current investigations focusing on the direct conversion of solar energy to stored

chemical energy could be divided into two categories34 One is open cycle solar system using

solar energy for the splitting of water into hydrogen andor the reduction of carbon dioxide into

methanol The stored chemical energy in hydrogen andor methanol would be released by

subsequent combustion process An alternative is closed cycle solar system also called

molecular solar thermal systems The low-energy precursor would convert to high-energy isomer

3

by photoisomerization This metastable isomer with high energy density would thermally

isomerize back to precursor along with releasing the stored energy34 Inspired by the existing

MOST including stilbenes azobenzenes anthracenes ruthenium fulvalene and norbornadiene-

quadricyclane systems35 the thermal isomerization of analogous polycyclic compounds is worthy

of exploration for possible energy storage and release due to their highly strained energy

Strained polycyclic hydrocarbons are often more stable than anticipated considering their

possession of large amounts of strain energy This fact provoked exploration of such molecules

as potential fuel sources due to the exothermicity manifest during activation The bicyclobutane

moiety plays an important structural role in high energy density fuels on the basis of its high

strain energy The thermal isomerization of bicyclobutane has gained considerable interest on

account of the various possible pathways of strain release36-40 The mechanism of the opening of

the two fused three-member rings is important to understand the release of thermal energy

related to liquid fuel vaporization ahead of the flame front41 Nguyen and Gordon examined the

isomerization channels of bicyclobutane to butadiene at the multiconfiguration self-consistent

field level and reported the allowed conrotatory pathway and forbidden disrotatory pathway40

They also showed that a multideterminant wavefunction was necessary to describe the forbidden

pathway due to the strong singlet biradical character Connecting the two methylene carbons of

bicyclobutane with a carbon chain results in a tricyclo structure which imparts additional steric

constraints The isomerization still proceeds through cleavage of two nonadjacent CndashC bonds in

the bicyclobutane moiety but the bridge-connected methylenes are no longer free to rotate during

the isomerization In the conrotatory pathway the orbitals comprising the cleaved bonds rotate in

4

the same direction ie both clockwise or both counterclockwise In the disrotatory pathway the

orbitals comprising the cleaved bonds rotate in opposite directions The conrotatory transition

state for bicyclobutane is about 15 kcal mol-1 lower in energy than the disrotatory transition state

so the conrotatory is labeled lsquolsquoallowedrsquorsquo and the disrotatory lsquolsquoforbiddenrsquorsquo When the two

methylene groups of bicyclobutane are bridged as shown in Figure 1 the conrotatory rotation of

the cleaving orbitals causes a trans double bond to form while for the disrotatory rotation both

double bonds are in the cis geometry The presence of a trans double bond in a six or seven

membered conjugated cyclic diene produces considerable bond strain This strain can also be

relieved by simple rotation of the trans double bond with a very small activation barrier42 It is

the highly strained nature of the trans double bond that is worthy of exploration for possible

energy storage motifs inspired by the strained ring quadricyclane to norbonadiene couple43

5

Figure 1 Schematic representation of conrotatory and disrotatory pathways In this dissertation the electro- and photocatalytic reduction of carbon dioxide for open

solar cycle system from experimental chemistry perspective were discussed Also the thermal

isomerization of tricylco-compounds for possible energy storage and release from computational

chemistry perspective were studied In chapter one electrocatalytic CO2 reduction with a

dinuclear rhenium complex and comparison of the monometallic and cooperative bimetallic

pathways were discussed After electrocatalytically evaluation of aforementioned dinuclear

rhenium complex photochemical CO2 reduction with mononuclear and dinuclear rhenium

catalysts bearing a pendant anthracene chromophore were studied in chapter two Chapter three

included the ab initio calculation of thermal isomerization of 34-diazatricyclo[410027]hept-3-

ene (DATCE) 34-diazatricyclo[410027]heptane (DATCA) and 345-

6

triazatricyclo[410027]hept-3-ene (TATCE) The ab initio study of thermal isomerization of

benzvalene to benzene and benzvalyne to benzyne were discussed in chapter four

This dissertation used materials from three articles in journals44-46 Chapter one used

content from the article in Inorganic Chemistry journal44 reprinted (adapted) with permission

from (Inorg Chem 201857159564-9575) Copyright (2018) American Chemical Society

Weiwei Yang Rebekah L Nelson and Jonah W Jurss synthesized and characterized the

catalyst Weiwei Yang Sayontani Sinha Roy and Jonah W Jurss performed and analyzed the

electrochemical measurements Winston C Pitts carried out the DFT calculations Chapter two

was based on the article in Chemical Communication journal45 (Chem Commun 2019 55 993)-

reproduced by permission of The Royal Society of Chemistry Weiwei Yang and Jonah W Jurss

synthesized and characterized the catalyst Nalaka P Liyanage and Jared H Delcamp collected

and analyzed the photocatalysis data Sayontani Sinha Roy obtained Stern-Volmer quenching

data Stephen Guertin Rebecca E Adams and Russel H Schmehl obtained photophysical

properties Chapter three was based on the article in Physical Chemistry Chemical Physics46

(PhysChemChemPhys 2018 20 26608) - reproduced by permission of the PCCP Owner

Societies It is coauthored by Weiwei Yang Kimberley N Poland and Steven R Davis Finally

some materials from those articles were incorporated in chapter introduction and chapter

conclusion44-46

7

CHAPTER I

ELECTROCATALYTIC CO2 REDUCTION WITH CIS AND TRANS CONFORMERS

OF A RIGID DINUCLEAR RHENIUM COMPLEX

11 Introduction

Mechanistic studies of Re(bpy)(CO)3X-type catalysts have provided evidence for the

concentration-dependent formation of dinuclear intermediates during catalysis161747-55 Indeed

bimetallic and monometallic pathways exist as dimer formation is in competition with CO2

reduction at a single metal49 Disentangling the contributions of competing pathways in addition

to the transient nature of their respective intermediates has made it difficult to assess the

possible advantages of two metal centers in activating and reducing CO2 in a cooperative

fashion A beneficial interaction between two active sites is further clouded as a Re-Re bonded

dimer has been indicted as a deactivated intermediate5253

Several bimetallic catalyst designs have been pursued based on flexible alkyl tethers5657

or hydrogen bonding interactions5859 which suffer from a lack of rigidity and variable solution

compositions Other examples feature dinucleating scaffolds that preclude intramolecular

bimetallic CO2 activation and conversion60-63 Thus the desirable design parameters surrounding

this approach are poorly understood

8

In this context we sought to develop catalysts with a rigid dinucleating ligand that

positions two rhenium active sites in close proximity with a predictable intermetallic distance

and orientation (Scheme 1) The ability to isolate and even select from competing mechanisms

(ie bimetallic vs monometallic pathways) would allow us to compare and understand

differences in efficiency activity and stability Herein the synthesis characterization and

electrocatalytic activity of homogeneous cis and trans conformers of a Re2 catalyst supported by

an anthracene-based polypyridyl ligand are described

Scheme 1 Synthesis of 18-di([22-bipyridin]-6-yl)anthracene 1 and its bimetallic Re(I) conformers cis-Re2Cl2 and trans-Re2Cl2

Cl ClO

O 1 Zn NH4OH (20) 80 oC 5 h

2 HCl iPrOH

Cl Cl

2 B B

Pd2(dba)3 + 4Xphos

dioxane 90 oC 2 d

B BO O O O

O

O O

O

N NBr

Pd(PPh3)4EtOH K2CO3toluene ∆ 2 d

NN

NN

NN

NN

Re ReClOC

COOCOC CO

Cl CO

cis-Re2Cl2 1

Re(CO)5Cl

toluene ∆1 d

1a88

1b88

86

trans-Re2Cl2

N

N

N

N

Re

Re

OC

OC

OC

OCCl

Cl

OC

CO

+

41 20

9

12 Experimental section

121 Materials and methods

Unless otherwise noted all synthetic manipulations were performed under N2 atmosphere

using standard Schlenk techniques or in an MBraun glovebox Toluene was dried with a Pure

Process Technology solvent purification system Anhydrous NN-dimethylformamide (DMF)

was purchased from Alfa Aesar packaged under argon in ChemSeal bottles The rhenium

precursor Re(CO)5Cl was purchased from Strem and stored in the glovebox All other chemicals

were reagent or ACS grade purchased from commercial vendors and used without further

purification 1H and 13C NMR spectra were obtained using a Bruker Advance DRX-500

spectrometer operating at 500 MHz (1H) or 126 MHz (13C) Spectra were calibrated to residual

protiated solvent peaks chemical shifts are reported in ppm Electrospray ionization mass

spectra (ESI-MS) were obtained with a Waters SYNAPT HDMS Q-TOF mass spectrometer

UV-Vis spectra were recorded on an Agilent Hewlett-Packard 8453 UV-Visible

Spectrophotometer with diode-array detector Infrared spectra were obtained on an Agilent

Technologies Cary 600 series FTIR spectrometer equipped with a PIKE GladiATR accessory

122 Electrochemical measurement

Electrochemistry was performed with a Bioanalytical Systems Inc (BASi) Epsilon

potentiostat Cyclic voltammetry studies employed a three-electrode cell equipped with a glassy

carbon disc (3 mm dia) working electrode a platinum wire counter electrode and a silver wire

quasi-reference electrode that was referenced using ferrocene as an internal standard at the end of

10

experiments Electrochemistry was conducted in anhydrous DMF containing 01 M Bu4NPF6

supporting electrolyte Solutions for cyclic voltammetry were thoroughly degassed with Ar or

CO2 before collecting data All voltammograms were cycled from the most positive potential to

the most negative potential and back

Controlled potential electrolysis were carried out in a 3-neck glass cell with a glassy

carbon rod (2 mm diameter type 2 Alfa Aesar) working electrode a silver wire quasi-reference

electrode and a platinum mesh (25 cm2 area 150 mesh) counter electrode that was separated

from the other electrodes in an isolation chamber comprised of a fine glass frit Solutions were

degassed with CO2 for 30 min before collecting data The applied potential values were

determined by cyclic voltammetry before controlled potential electrolysis were performed

Evolved gases during electrolysis measurements was quantified by gas chromatographic analysis

of headspace samples using an Agilent 7890B Gas Chromatograph and an Agilent PorapakQ (6

long 18 OD) column CO was measured using an FID detector while H2 was quantified at

the TCD detector Constant stirring was maintained during electrolysis Integrated gas peaks

were quantified with calibration curves obtained from known standards purchased from

BuyCalGascom From the experimental amount of product formed during electrolysis Faradaic

efficiencies were calculated against the theoretical amount of product possible based on the

accumulated charge passed and the stoichiometry of the reaction

UV-visible spectroelectrochemical (SEC) measurements were conducted with a

commercial ldquohoneycombrdquo thin-layer SEC cell from Pine Research Instrumentation employing a

11

gold working electrode a silver wire quasi-reference electrode and a platinum wire counter

electrode

123 X-ray crystallography

Single crystals were coated with Paratone-N hydrocarbon oil and mounted on the tip of a

MiTeGen micromount Temperature was maintained at 100 K with an Oxford Cryostream 700

during data collection at the University of Mississippi Department of Chemistry and

Biochemistry X-ray Crystallography Facility Samples were irradiated with Mo-Kα radiation

with λ = 071073 Aring using a Bruker Smart APEX II diffractometer equipped with a Microfocus

Sealed Source (Incoatec ImicroS) and APEX-II detector The Bruker APEX2 v 20091 software

package was used to integrate raw data which were corrected for Lorentz and polarization

effects64 A semi-empirical absorption correction (SADABS) was applied65 The structure was

solved using direct methods and refined by least-squares refinement on F2 and standard

difference Fourier techniques using SHELXL66-68 Thermal parameters for all non-hydrogen

atoms were refined anisotropically and hydrogen atoms were included at ideal positions Poorly

resolved outersphere DMF molecules could not be modeled successfully in the difference map

The data was treated with the SQUEEZE procedure in PLATON6970 details are provided in the

CIF file

124 Computational methods

All calculations were performed in Gaussian 0971 All energies discussed in this work

contain zero point energy corrections Global minimums of the cis and trans conformers were

12

located using density functional theory (DFT) and the ωB97X-D72 functional73 The 6-311+G

basis set was used for all coordinating atoms which includes the carbon monoxide The 6-311G

basis was used for all hydrogen and carbon atoms of the ligand manifold LanL2TZ (f) was used

for the two rhenium atoms The minimums were confirmed by calculating the harmonic

vibrational frequencies and finding all real values To obtain a structure close to the transition

state (TS) of conformational isomerization (via rotation) an initial relaxed scan was performed

using semi-empirical PM6 and was parametrized by the dihedral angle C(14)-C(15)-C(23)-N(39)

or C(6)-C(5)-C(29)-N(40) for TS1 and TS2 respectively as labeled in Figure A1 From these

scans the maximum was used as a starting point for a transition state optimization using the

Berny algorithm at the level of theory and basis sets mentioned previously

Structural optimization and infrared spectra calculations were performed using the BP86-

D3def2-TZVP functional-basis set combination with Beckrsquos and Johnstonrsquos dispersion

corrections The rhenium atoms were described with the LanL2TZ (f) effective core potential

with the added polarization function These calculations also included DMF solvent-induced

corrections using the COSMO solvation model Frequency analysis confirmed global minimums

Global minimums for the Re-Re dimers were found using the ωB97X-D functional with

basis sets LanL2TZ (f) for rhenium atoms and 6-31++G for all light atoms An ultrafine

numerical integration grid was employed for both species Cartesian coordinates and energies are

given in Table A1-Table A10

13

125 Synthetic procedures

Re(bpy)(CO)3Cl was prepared as previously described74 Ligand precursors 6-bromo-

22rsquo-bipyridine75 and 18-bis(neopentyl-glycolatoboryl)anthracene76 were prepared according to

literature procedures

18-di(22rsquo-bipyridine)anthracene 1 In an oven-dried 2-neck round bottom flask were

added 18-bis(neopentylglycolatoboryl)anthracene (10 g 249 mmol) 6-bromo-22rsquo-bipyridine

(14 g 597 mmol) and Pd(PPh3)4 (0172 g 6 mol ) under inert atmosphere Degassed toluene

(50 mL) ethanol (5 mL) and 2 M aqueous K2CO3 (5 mL) were added to the reaction vessel

under N2 and refluxed for 2 days After cooling to room temperature 25 mL saturated aqueous

NH4Cl and 25 mL H2O were added to the mixture The crude product was extracted with

dichloromethane and purified by silica gel chromatography (11 hexanesethyl acetate) to yield

pure product (104 g 86) 1H NMR (500 MHz DMSO-d6) δ 980 (s 1H) 883 (s 1H) 862

(ddd J = 47 18 09 Hz 2H) 827 (d J = 84 Hz 2H) 798 (dt J = 78 10 Hz 2H) 783 (dq J

= 79 10 Hz 2H) 778 ndash 773 (m 4H) 771 ndash 765 (m 4H) 757 (td J = 77 18 Hz 2H) 733

(ddt J = 69 48 11 Hz 2H) 13C NMR (126 MHz DMSO-d6) δ 15760 15489 15452

14901 13799 13785 13701 13155 12914 12906 12738 12691 12550 12492 12384

12361 11996 11861 ESI-MS (M+) mz calc for [1 + H+] 4872 found 4872

18-di(22rsquo-bipyridine)anthracene(Re(CO)3Cl)2 Re2Cl2 To an oven-dried 2-neck round

bottom flask were added 18-di(22rsquo-bipyridine)anthracene (100 mg 0205 mmol) and

Re(CO)5Cl (148 mg 041 mmol) under inert atmosphere Anhydrous toluene (5 mL) was added

and the reaction mixture was refluxed overnight The mixture was cooled to room temperature

14

the precipitate was collected by filtration with a glass frit and washed with toluene and diethyl

ether several times The crude product was purified by silica gel chromatography with gradient

elution from dichloromethane to 23 acetonedichloromethane using a Biotage automated flash

purification system to give pure compounds cis-Re2Cl2 (41 yield) and trans-Re2Cl2 (20)

cis-Re2Cl2 1H NMR (500 MHz DMSO-d6) δ 904 (d J = 54 Hz 2H) 887 (s 1H) 877

(d J = 83 Hz 2H) 868 (d J = 81 Hz 2H) 839 (d J = 85 Hz 2H) 835 (t J = 79 Hz 2H)

790 (t J = 79 Hz 2H) 783 (s 1H) 774 (m 4H) 761 (d J = 76 Hz 2H) 754 (d J = 66 Hz

2H) 13C NMR (126 MHz DMF-d7) δ 19947 19509 19507 16187 15822 15757 15410

14111 14077 13341 13190 13157 13142 13102 12877 12871 12848 12832 12682

12610 12593 12494 12404 ATR-FTIR ν(CO) at 2015 1915 (with shoulder at 1924) and

1871 cm-1 ESI-MS (M+) mz calc for [cis-Re2Cl2 + Cs+] 12309 found 12309

trans-Re2Cl2 1H NMR (500 MHz DMSO-d6) δ 901 (d J = 54 Hz 1H) 898 (d J = 54

Hz 1H) 887 (s 1H) 877 (d J = 83 Hz 1H) 873 (d J = 82 Hz 1H) 861 (d J = 81 Hz 1H)

857 (d J = 81 Hz 1H) 842 (t J = 80 Hz 1H) 839 - 832 (m 3H) 802 (t J = 79 Hz 1H)

783 (t J = 66 Hz 1H) 777 ndash 768 (m 3H) 765 (d J = 71 Hz 2H) 753 (t J = 78 Hz 1H)

749 (d J = 68 Hz 1H) 744 (d J = 77 Hz 1H) 733 (s 1H) 13C NMR (126 MHz DMF-d7) δ

19936 19883 19514 19484 19195 19096 16248 16245 15790 15783 15760 15706

15420 15409 14180 14136 14112 14091 14059 13959 13331 13322 13191 13160

13150 13092 13057 13037 12928 12881 12861 12851 12667 12612 12601 12590

12442 12439 12392 ATR-FTIR ν(CO) at 2015 and 1891 cm-1 ESI-MS (M+) mz calc for

[trans-Re2Cl2 + Cs+] 12309 found 12309

15

1-(22rsquo-bipyridine)anthracene 2 In an oven-dried 2-neck round bottom flask were added

1-(neopentylglycolatoboryl)anthracene (10 g 346 mmol) 6-bromo-22rsquo-bipyridine (10 g 415

mmol) and Pd(PPh3)4 (02 g 5 mol ) under inert atmosphere Degassed toluene (50 mL)

ethanol (5 mL) and 2 M aqueous solution of K2CO3 (5 mL) were added to the reaction vessel

under N2 and refluxed for 2 days After cooling to room temperature 25 mL saturated NH4Cl

and 25 mL H2O were added into mixture The crude product was extracted with dichloromethane

and purified by silica gel chromatography (51 hexanesethyl acetate) to yield pure product (06

g 52) 1H NMR (500 MHz DMSO-d6) δ 884 (s 1H) 876 (dd J = 889 47 Hz 1H) 872 (s

1H) 852 (d J = 78 Hz 1H) 841 (d J = 80 Hz 1H) 824 (d J = 84 Hz 1H) 818 (t J = 78

Hz 1H) 813 (d J = 85 Hz 1H) 800 (d J = 84 Hz 1H) 793 (td J = 78 16 Hz 1H) 785 (d

J = 76 Hz 1H) 773 (d J = 65 Hz 1H) 766 (dd 1H) 758 ndash 752 (m 1H) 751 ndash 744 (m

2H) 13C NMR (126 MHz DMSO-d6) δ 15847 15582 15549 14984 13887 13832 13789

13216 13198 13149 12973 12941 12906 12826 12778 12713 12643 12626 12569

12550 12486 12479 12107 11957 ESI-MS (M+) mz calc for [2 + H+] 3331 found

3331

[1-(22rsquo-bipyridine)anthracene][Re(CO)3Cl] anthryl-Re To an oven-dried 2-neck round

bottom flask were added 1-(22rsquo-bipyridine)anthracene (100 mg 0300 mmol) and Re(CO)5Cl

(1085 mg 0300 mmol) under inert atmosphere Anhydrous toluene (5 mL) was added and the

reaction mixture was refluxed overnight The mixture was cooled to room temperature the

precipitate was collected by filtration with a glass frit and washed with toluene and diethyl ether

several times Pure product was obtained by crystallization from dichloromethanehexanes (161

16

mg 84) Two conformers are present by 1H NMR with slow rotation observed at room

temperature ESI-MS (M+) mz calc for [anthryl-Re + Cs+] 7709453 found 7709452

Elemental analysis for C28H16N2O4Rebull15H2O calcd C 4876 H 288 N 421 found C 4909 H

288 N 422

13 Synthesis and characterization

The synthesis of 18-di([22-bipyridin]-6-yl)anthracene (1) and its metalation to generate

conformers cis-Re2Cl2 and trans-Re2Cl2 is shown in Scheme 1 As previously described7718-

dichloroanthraquinone is reduced with Zn to give 18-dichloroanthracene (1a) Next the 18-

diboronate ester (1b) is furnished by a Pd-catalyzed borylation with bis(neopentyl

glycolato)diboron76 The boronate ester is reacted directly by Suzuki cross coupling with 6-

bromo-22rsquo-bipyridine to give dinucleating ligand 1 in 86 yield Metalation was achieved by

refluxing the ligand with two equivalents of Re(CO)5Cl in anhydrous toluene overnight to give a

mixture of two dinuclear Re(I) conformers cis-Re2Cl2 and trans-Re2Cl2 Despite the possible

formation of up to seven isomers (Figure A2) only two species are observed in the reaction

mixture under these conditions as shown in the crude 1H NMR spectrum (Figure A3) Two

narrow closely-spaced bands were separated by silica gel chromatography to give an overall

isolated yield of 61 We note that solvent-dependent isomer formation has been reported

previously for di- and trinuclear Re(CO)3-based compounds78 1H NMR spectra of the purified

cis and trans conformers are shown in Figure 2 From the NMRs there is a symmetric species

(cis-Re2Cl2) with 12 chemically distinct protons and an asymmetric species (trans-Re2Cl2)

displaying 22 different proton signals Infrared spectroscopy in DMF established the presence of

17

fac-Re(CO)3 fragments with carbonyl stretching frequencies ν(CO) for cis-Re2Cl2 at 2019 1915

and 1890 cm-1 and for trans-Re2Cl2 at 2014 1910 and 1888 cm-1 (Figure A4) For comparison

the CO stretching frequencies of the parent complex fac-Re(bpy)(CO)3Cl are at 2019 1914 and

1893 cm-1 in DMF16

Figure 2 1H NMR spectra (500 MHz DMSO-d6) showing the aromatic region of A) cis-Re2Cl2 and B) trans-Re2Cl2

X-ray quality crystals of the asymmetric trans conformer were obtained by slow

isopropyl ether diffusion into a concentrated DMF solution The crystal structure of trans-Re2Cl2

is shown in Figure 3 concurrently lending support for a symmetric configuration of the cis

conformer which is accessible by rotation (cis harr trans) as observed at elevated temperatures by

1H NMR However no interconversion is observed at room temperature over the course of 2

days

74757677787980818283848586878889909192f1 (ppm)

199

195

416

108

201

220

192

192

200

096

200

7727374757677787980818283848586878889909192f1 (ppm)

088

098

099

106

198

328

099

088

300

107

088

092

090

095

084

092

102

A

B

18

Figure 3 Crystal structure of trans-Re2Cl2 Hydrogen atoms are omitted for clarity Thermal ellipsoids are shown at the 70 probability level Our catalyst design aims to channel reactivity through a single mechanism by allowing both

active sites to be in close proximity for cooperative catalysis or by isolating each metal center for

single-site activity Importantly as active sites are generated following chloride dissociation

from the metal two symmetric cis conformers are possible one in which the chloro ligands face

each other (cis-Re2Cl2) and the other which has its chloro ligands oriented outward (cis 2 as

labeled in Figure A2) Density Functional Theory (DFT) calculations were used to investigate

the barrier to rotation of Re(bpy) moieties to either side of the anthracene bridge by which the

trans conformer may interconvert to either of the symmetric cis conformers in solution Since the

structure of trans-Re2Cl2 is known the energy barrier associated with rotational isomerization

from trans-Re2Cl2 was calculated (Figure A1) By DFT the barrier to rotation from the trans

conformer to cis-Re2Cl2 (272 kcalmol) is 46 kcalmol lower in energy than rotation to cis 2

(318 kcalmol) These calculations provide indirect evidence that the isolated cis conformer has

its chloro ligands facing ldquoinrdquo (denoted cis-Re2Cl2 as depicted in Scheme 1) Toward more direct

19

evidence the infrared spectra of cis-Re2Cl2 and cis 2 were calculated by DFT Notably cis-

Re2Cl2 is predicted to have 3 ν(CO) absorption bands while cis 2 is expected to have 4 ν(CO)

vibrational modes (Figure A5) The experimental FTIR spectrum of the cis conformer (Figure

A4) confirms its stereochemistry

14 Results and discussion

141 Electrochemistry

Following characterization the redox behavior of cis-Re2Cl2 and trans-Re2Cl2 was

analyzed in the absence of CO2 by cyclic voltammetry in anhydrous DMF containing 01 M

Bu4NPF6 supporting electrolyte Re(bpy)(CO)3Cl and a mononuclear derivative (anthryl-Re)

bearing a pendant anthracene (shown in Figure 4) were studied in parallel to provide insight into

catalytic activity and ligand-based redox chemistry Cyclic voltammograms (CVs) were

referenced internally at the end of experiments to the ferroceniumferrocene (Fc+0) couple The

electrochemical properties of Re(bpy)(CO)3Cl have been studied extensively most often in

acetonitrile solutions Its CV in DMF overlaid with that of anthryl-Re (Figure 4) exhibits a

quasireversible redox process with Epc at -180 V vs Fc+0 and an irreversible reduction at -225

V Notably the CV of anthryl-Re has a third reduction at -254 V that is absent in the parent

complex Similar behavior is observed for the dinuclear catalysts (Figure 4) CVs of cis-Re2Cl2

and trans-Re2Cl2 reveal two closely-spaced quasireversible one-electron reductions at Epc = -

177 and -187 V and Epc = -178 and -188 V respectively followed by reductions at Epc = -234

and -265 V and Epc = -240 and -267 V respectively at a scan rate of 100 mVs The number of

20

electrons transferred in each redox process based on integrated cathodic peak areas corresponds

to a 1121 stoichiometry From scan rate dependent CVs of the dinuclear conformers and both

mononuclear complexes linear fits were obtained in plots of the reductive peak current (ipc)

versus the square root of the scan rate (ν12) consistent with freely diffusing systems (Figure A6-

Figure A9)7980

Figure 4 CVs of A) 2 mM Re(bpy)(CO)3Cl and anthryl-Re and B) 1 mM cis-Re2Cl2 and trans-Re2Cl2 in DMF01 M Bu4NPF6 under Ar glassy carbon disc ν = 100 mVs

Comproportionation constants (KC) for the dinuclear catalysts were estimated from the

overlapping one-electron reductions as a measure of electronic coupling between Re(bpy)

units81 Based on the difference in potentials ∆E between Ep1c and Ep2c a KC value of 50 was

calculated for both Re2 conformers indicative of weak electronic coupling through the

anthracene bridge81 Weak electronic coupling is not surprising given the number of bonds

between redox sites These results are summarized in Table 2

N

NRe

OC

OCCl

CO

21

Table 2 Reduction potentials diffusion coefficients and comproportionation constants (KC) from cyclic voltammetry in anhydrous DMF01 M Bu4NPF6 solutions

Catalyst Ep1c Ep2c Ep3c Ep4c

cis-Re2Cl2 -177 -187 -234 -265

KC = 50

trans-Re2Cl2 -178 -188 -240 -267

KC = 50

Re(bpy)(CO)3Cl -180 -225 - - D = 540 x 10-6 cm2 s-1

anthryl-Re -182 -229 -254 - D = 548 x 10-6 cm2 s-1

On the basis of these results and previous work5859626382 we assign the most positive

overlapping one-electron redox events to ligand-centered bipyridine reductions to form

[ReI(bpybull)(CO)3Cl]ndash moieties followed by a third (overall) reductive process involving each of

the Re(bpy) units totaling two electrons The most negative redox event is ascribed to a one-

electron anthracene-based reduction A CV of free ligand 1 is shown in Figure A10

Electrocatalytic CO2 reduction by the dinuclear conformers and monomers

Re(bpy)(CO)3Cl and anthryl-Re was then investigated by cyclic voltammetry CVs of cis-Re2Cl2

and trans-Re2Cl2 at 1 mM concentrations and of monomers at concentrations of 2 mM are shown

in Figure 5 in DMF solutions under Ar and CO2 atmospheres The monomer catalyst

concentrations were doubled to maintain a consistent concentration with respect to rhenium

22

Figure 5 Cyclic voltammetry in Ar- and CO2-saturated DMF01 M Bu4NPF6 solutions with A) 1 mM cis-Re2Cl2 B) 1 mM trans-Re2Cl2 C) 2 mM Re(bpy)(CO)3Cl and D) 2 mM anthryl-Re glassy carbon disc ν = 100 mVs The background under CO2 is shown with a dashed blue line

For an electrocatalytic reaction involving heterogeneous electron transfers at the

electrode surface the peak catalytic current is described by equation 183-85

119894119894119888119888119888119888119888119888 = 119899119899119888119888119888119888119888119888119865119865119865119865[119888119888119888119888119888119888](119863119863119896119896119888119888119888119888119888119888[119878119878]119910119910)12 (1)

B

D

23

where icat is the limiting catalytic current in the presence of CO2 ncat corresponds to the

number of electrons transferred in the catalytic process (here ncat = 2 as CO2 is reduced to CO) F

is Faradayrsquos constant A is the area of the electrode [cat] is the molar concentration of the

catalyst D is the diffusion coefficient kcat is the rate constant of the catalytic reaction and [S] is

the molar concentration of dissolved CO2 Applying eq 1 the catalytic mechanisms of cis-Re2Cl2

and trans-Re2Cl2 were probed using cyclic voltammetry to determine reaction orders with

respect to [CO2] and [cat] (Figure A11 and Figure A12 respectively) First gas mixtures of Ar

and CO2 were used to vary the partial pressure of CO2 from 0 to 1 atm to reveal a linear increase

in catalytic current for CO2 reduction as a function of the square root of dissolved CO2

concentration for both cis-Re2Cl2 and trans-Re2Cl2 catalysts (Figure 6) The concentration of

dissolved CO2 in DMF under saturation conditions at 1 atm is 020 M86

Figure 6 CO2 concentration dependence for A) 1 mM cis-Re2Cl2 and B) 1 mM trans-Re2Cl2 in DMF01 M Bu4NPF6 glassy carbon disc ν = 100 mVs Catalytic current (120583120583A) is plotted versus the square root of [CO2]

A B

24

Likewise the dependence of catalytic current (icat) on the concentration of each dinuclear

rhenium catalyst ([cat]) in CO2-saturated solutions was determined (Figure 7)

Figure 7 Catalyst concentration dependence for A) cis-Re2Cl2 and B) trans-Re2Cl2 in CO2-saturated DMF01 M Bu4NPF6 solutions glassy carbon disc ν = 100 mVs Linear fits with slopes of 1 were obtained in log-log plots of catalytic current (120583120583A) versus catalyst concentration (mM)

For both conformers the data indicates a first order dependence on [Re2Cl2] and a first

order dependence on [CO2] in the rate determining step as expressed by the following rate law

Rate = minus[CO2]

dt = kcat[Re2Cl2][CO2]

It was not possible on the basis of reaction orders alone to distinguish between the

reaction mechanisms of cis and trans conformers Log-log plots were critical for the correct

kinetic analysis of these catalysts since plots of catalytic current vs [trans-Re2Cl2] as well as

catalytic current vs [trans-Re2Cl2]12 both gave reasonable linear fits (Figure A13) The log-log

plots confirm the reactions are first order in catalyst with slopes of 1 (Figure 7)

B

25

Our initial inquiry regarding a half-order dependence on catalyst concentration

specifically for trans-Re2Cl2 emerged from a previous mechanistic study involving a dinuclear

palladium complex in which its polydentate phosphine ligand was designed to prevent

cooperative intramolecular CO2 binding between active sites8788 A half-order dependence on

catalyst concentration was reported and explained by assuming the metal active sites operate

independently of one another such that only half of the complex is intimately involved in the

rate determining step88 As rationalized however a first order dependence would be expected A

square root dependence on catalyst concentration is typically observed following rate-limiting

dissociation of a dinuclear pre-catalyst that is in reversible equilibrium with the active form8990

Several plausible modes of reactivity with a dinuclear catalyst for CO2 reduction are

expected to yield a first order dependence on catalyst concentration (1) both metal centers

participate in the intramolecular activation or binding of CO2 and its conversion (2) only one

metal center reacts with CO2 while the other acts as a spectator (3) only one metal center reacts

with CO2 while the other serves as an electron reservoir capable of intramolecular electron

transfer or (4) both metal centers operate independently and react with one CO2 molecule each

In cases (2) and (3) the metal fragment that does not bind CO2 can be thought of more simply as

(2) an elaborate ligand substituent of variable electronics depending on its redox state or (3) a

pendant redox mediator that supplies electron(s) to the active site neither of which would give a

half-order dependence on catalyst concentration

26

142 Catalytic rates and faradaic efficiencies

With these results in hand we sought to compare the catalytic rates of the cis and trans

conformers along with Re(bpy)(CO)3Cl and its anthracene-functionalized derivative anthryl-Re

The quantity (icatip)2 can serve as a useful benchmark of catalytic activity that is proportional to

turnover frequency (TOF) as shown in equation 2 where ν is the scan rate np is the number of

electrons transferred in the noncatalytic Faradaic process R is the ideal gas constant T is the

temperature (in K) and ip is the peak current observed for the catalyst in the absence of

substrate5859

119879119879119879119879119865119865 = 119896119896119888119888119888119888119888119888[1198621198621198791198792] = 1198651198651198651198651198991198991199011199013

11987711987711987711987704463119899119899119888119888119888119888119888119888

21198941198941198881198881198881198881198881198881198941198941199011199012 (2)

Application of eq 2 requires steady state behavior which can often be established at

sufficiently fast scan rates that avoid substrate depletion and give rise to a limiting catalytic

current plateau Linear sweep voltammograms of cis-Re2Cl2 (1 mM) trans-Re2Cl2 (1 mM) and

the mononuclear catalysts (2 mM) were conducted in DMF01 M Bu4NPF6 solutions under

argon and CO2 as a function of scan rate (Figure A14) While scan rate independence was not

completely reached estimated TOFs using eq 2 are plotted versus scan rate in Figure A15 where

TOFs of 353 229 111 and 192 s-1 were identified for cis-Re2Cl2 trans-Re2Cl2

Re(bpy)(CO)3Cl and anthryl-Re respectively Alternatively Costentin and Saveacuteants foot-of-

the-wave analysis (FOWA)85919293 can be applied to find intrinsic catalytic rates via equation 3

119894119894119894119894119901119901

=224

119877119877119877119877119865119865119865119865119899119899119901119901

32119896119896119888119888119888119888119888119888[1198621198621198621198622]

1+119890119890119890119890119890119890 119865119865119877119877119877119877(119864119864minus1198641198641198881198881198881198881198881198882) (3)

27

This electroanalytical method provides access to a TOF maximum in which the observed

catalytic rate constant kcat can be determined at the foot of the catalytic wave where competing

factors (ie substrate depletion catalyst inhibition or decomposition) are minimal Indeed scan

rate independent TOFs were obtained by FOWA (Figure A16) In eq 3 1198641198641198881198881198881198881198881198882 is the half-wave

potential of the catalytic wave From the slope of the linear portion of a plot of iip versus

11+exp[(FRT)(119864119864ndash1198641198641198881198881198881198881198881198882)] kcat can be calculated The maximum TOF under saturation

conditions is then found from TOF = kcat[CO2]

Maximum TOFs determined via FOWA for the dinuclear catalysts (110 s-1 cis-Re2Cl2

44 s-1 trans-Re2Cl2) are higher than that of the mononuclear parent catalyst (15 s-1) at the same

effective concentrations Likewise the cis conformer is considerably more active than its trans

counterpart consistent with the estimated TOFs from eq 2 With regards to anthryl-Re (41 s-1)

the pendant anthracene results in a higher TOF relative to unsubstituted Re(bpy)(CO)3Cl whereas

very similar rates (via both electroanalytical equations) are observed relative to trans-Re2Cl2

Comparable TOFs of anthryl-Re and trans-Re2Cl2 are consistent with the isolated active sites of

the dinuclear complex on opposite sides of the anthracene bridge Notably slow catalysis begins

after the first overlapping one-electron reductions at around -19 V with dinuclear catalysts

while no activity is observed until the second reduction at -21 V for the monomers

Broslashnsted acids are frequently added to polar aprotic solvents to promote the proton-

coupled reduction of CO2 Indeed significant enhancements in the electrocatalytic CO2 reduction

activity of mononuclear Re catalysts have been observed with various proton source

additives239495 The influence of four different acids (water methanol phenol and 222-

28

trifluoroethanol (TFE)) on the CO2 reduction activity of cis-Re2Cl2 in DMF was investigated

(Figure A17) This selection of proton sources affords a good range of acidity with the following

pKas reported in DMSO96 314 (H2O)97 290 (MeOH)97 235 (TFE)98 180 (PhOH)99 Catalyst

cis-Re2Cl2 shows a decrease in current upon addition of these acids However the onset of fast

catalysis is significantly more positive after the addition of a proton source relative to anhydrous

DMF From cyclic voltammetry added water produces the most promising catalytic activity for

CO2 reduction with cis-Re2Cl2 of the four Broslashnsted acids investigated taking into account its

nominal activity under argon Accordingly the amount of added H2O was optimized for cis-

Re2Cl2 by plotting icat vs H2O concentration where catalysis reached a maximum with 3 M H2O

(Figure A18) The catalytic activity of each catalyst in the presence of 3 M H2O is shown in

Figure 8 for comparison

29

Figure 8 Cyclic voltammograms of A) 1 mM cis-Re2Cl2 B) 1 mM trans-Re2Cl2 C) 2 mM Re(bpy)(CO)3Cl and D) 2 mM anthryl-Re with 3 M H2O in DMF01 M Bu4NPF6 under Ar (black) and CO2 (red) glassy carbon disc 120584120584 = 100 mVs

A thermodynamic potential of -073 V vs Fc+0 for the 2endash2H+ CO2CO couple in pure

DMF has been determined via a thermochemical approach100 In the presence of a Broslashnsted acid

this standard potential shifts according to equation 4 in which the pKa of the acid must be taken

into account100

C

A B

D

30

119864119864 = 1198641198641198621198621198621198622119862119862119862119862(119863119863119863119863119865119865)0 minus 00592 ∙ 119901119901119901119901119888119888 (4)

As previously described carbonic acid (H2CO3 pKa = 737) is more acidic than water in

DMF so its pKa was used in eq 4 to give an estimated reduction potential of -117 V for the

CO2CO couple in DMFH2O solutions6263 Using these standard potentials a summary of TOFs

from anhydrous DMF and observed overpotentials from Figure 5 and Figure 8 based on Ecat2 is

presented in Table 3 Ecat2 is a reliable metric that corresponds to the steepest point or nearly so

in the catalytic wave of the current-potential profile101

Table 3 Summary of electrocatalysis obtained from cyclic voltammetry

Catalyst TOF (s-1) eq 2

TOF (s-1) eq 3

Ecat2

(120578120578)a Ecat2

(120578120578)b

cis-Re2Cl2 353 110 -229 (156)

-209 (092)

trans-Re2Cl2 229 44 -234 (161)

-195 (078)

Re(bpy)(CO)3Cl 111 15 -222 (149)

-204 (087)

anthryl-Re 192 41 -226 (153)

-218 (101)

a Anhydrous DMF b DMF with 3 M H2O Ecat2 is the potential at which the current is equal to icat2 Overpotentials reported here were calculated from expression 120578120578 = 1198641198641198881198881198881198881198881198882 minus 1198641198641198621198621198621198622119862119862119862119862

0

Controlled potential electrolyses were carried out to identify products and Faradaic

efficiencies in an air-tight electrochemical cell using a glassy carbon rod working electrode and

CO2-saturated solutions The applied potential (Eappl) corresponds to the potential at which

maximum current was observed in cyclic voltammograms taken in the same set-up prior to

electrolysis Headspace gases and electrolytic solutions were analyzed by gas chromatography

1H NMR and FTIR spectroscopies102-104 CO was found to be the only detectable product under

31

these conditions where Eappl is -24 or -25 V (Table 4) No other products were observed In

addition to infrared spectroscopy a titration with barium triflate was also conducted to

investigate carbonate as a potential product Formation of BaCO3 was not apparent20102103 The

absence of carbonate indicates that the dinuclear catalysts do not mediate the reductive

disproportionation of CO2 ie 2CO2 + 2eminus ⎯ CO + CO3

2minus at these potentials consistent with

earlier results with Re(bpy)(CO)3Cl in DMF solutions47 It is well-established that under

anhydrous conditions protons can be generated by Hofmann degradation of the quaternary

alkylammonium cation of the supporting electrolyte4798105 This degradation is thought to arise

from a highly basic metal carboxylate intermediate that is capable of deprotonating the

tetrabutylammonium ion98105 consistent with infrared stopped-flow measurements in the

absence of an added proton source106

Table 4 Summary of controlled potential electrolyses and Faradaic efficiencies for CO2 reduction under various conditions

Catalyst Time (min) Eappl (V) Charge Passed (C) CO () cis-Re2Cl2 60 25 152 plusmn 032 81 plusmn 1

trans-Re2Cl2 60 25 060 plusmn 008 89 plusmn 6 Re(bpy)(CO)3Cl 60 25 117 plusmn 015 78 plusmn 10

cis-Re2Cl2 (3 M H2O) 60 24 096 plusmn 022 59 plusmn 5

trans-Re2Cl2 (3 M H2O) 60 24 101 plusmn 009 74 plusmn 1

Re(bpy)(CO)3Cl (3 M H2O) 60 24 092 plusmn 029 65 plusmn 6

cis-Re2Cl2 180 20 224 plusmn 037 52 plusmn 5

cis-Re2Cl2 600 20 594 plusmn 082 trans-Re2Cl2 180 20 101 plusmn 012 49 plusmn 5 cis-Re2Cl2 (3 M H2O) 600 20 627 plusmn 003 47 plusmn 3

32


At lower applied potentials Re(bpy)(CO)3Cl is known to catalyze the reductive

disproportionation of CO2 through the so-called ldquoone-electron pathwayrdquo 47 Following its one-

electron reduction the parent catalyst reduces CO2 in a bimolecular process to give CO and

CO32ndash In this mechanism two singly-reduced catalysts are proposed to bind CO2 to generate a

Re2 carboxylate-bridged intermediate that undergoes insertion with a second equivalent of CO2

before reductive disproportionation Here CO2 acts as an oxide acceptor to facilitate a proton-

independent conversion of CO2 to CO By inference less basic intermediates are generated at

these less reducing potentials and oxide transfer to CO2 is favored over Hofmann degradation

We note that the hydrogen-bonded Re(bpy) dimers developed by Kubiak and coworkers also

promote this bimolecular pathway with enhanced rates5859

In this context we investigated the cis and trans conformers at applied potentials

immediately following the first overlapping one-electron reductions Controlled potential

electrolyses were conducted in anhydrous DMF01 M Bu4NPF6 as well as solutions containing 3

M H2O Unsurprisingly trans-Re2Cl2 was found to catalyze the reductive disproportionation of

CO2 at an applied potential of -20 V in anhydrous DMF Given its solid-state structure catalytic

activity analogous to Re(bpy)(CO)3Cl was expected for the trans conformer and carbonate was

identified as a co-product by infrared spectroscopy with strong C-O stretching frequencies

observed at ~1450 and 1600 cm-1 (Figure 9) and subsequent precipitation of BaCO3 from DMF

solutions 103107 Conversely carbonate was not observed with cis-Re2Cl2 In order to bolster this

33

result and ensure that carbonate is not simply sequestered in a stable species (ie bound between

Re centers) long-term electrolysis were performed in which the evolved CO amounts to greater

than 2 turnovers with respect to moles of catalyst in solution On this basis cis-Re2Cl2 does not

catalyze the reductive disproportionation of CO2 consistent with the infrared spectra in Figure 9

Presumably restricted rotation of the Re(bpy) fragments in cis-Re2Cl2 impedes the CO2 insertion

step and favors protonation of the CO2 adduct by slow Hofmann degradation

Figure 9 FTIR spectra of A) trans-Re2Cl2 and B) cis-Re2Cl2 samples before and after electrolysis Electrolyzed solutions are evaporated to dryness and washed with the dichloromethane to remove the Bu4NPF6 electrolyte The resulting solid is analyzed

With 3 M H2O at the lower applied potential (-20 V vs Fc+0) carbonate or bicarbonate

is not produced by cis-Re2Cl2 or trans-Re2Cl2 Authentic samples of tetrabutylammonium

carbonate and tetrabutylammonium bicarbonate were synthesized107108 and detected by FTIR

using the established protocol and barium triflate titration to validate these results The presence

of water as a proton source enables the proton-coupled reduction of CO2 ie CO2 + 2H+ +

B

cis-Re2Cl2

34

2endash rarr CO + H2O at lower overpotentials Representative charge-time profiles from electrolyses

in DMF solutions are overlaid in Figure A19 Experiments were performed in duplicate and

results are summarized in Table 4

143 UV-Vis spectroelectrochemistry

Additional insight into the electrocatalytic CO2 reduction mechanisms of the cis and

trans conformers was gained from UV-Vis spectroelectrochemical measurements Data was

collected stepwise at increasingly negative applied potentials under argon atmosphere using a

thin-layer cell with a ldquohoneycombrdquo working electrode Representative absorption spectra vs time

(Figure 10) are shown for cis-Re2Cl2 and trans-Re2Cl2

Figure 10 UV-Vis spectroelectrochemistry with A) 05 mM cis-Re2Cl2 at -17 V vs AgAgCl B) 05 mM trans-Re2Cl2 at -17 V vs AgAgCl C) 05 mM cis-Re2Cl2 at -20 V vs AgAgCl D) 05 mM trans-Re2Cl2 at -20 V vs AgAgCl in Ar-saturated DMF01 M Bu4NPF6 solutions

D

35

trans-Re2Cl2 catalysts display a new absorption peak at 517 nm consistent with the one-

electron reduced species109 The terminology used here refers to reduction at a single rhenium

site to facilitate comparison with earlier studies on mononuclear catalysts The catalysts have

been reduced by two electrons in total At a more negative applied potential of -20 V vs Ag+

absorption bands at 562 nm (cis-Re2Cl2) and 570 nm (trans-Re2Cl2) appear indicative of the

two-electron reduced species17 Upon closer inspection of the absorption spectra obtained with

Eappl = -17 V vs Ag+ a broad band centered around 850 nm also emerges for the trans

conformer This feature is characteristic of a Re-Re bonded dimer17 presumably a Re4 species in

this case formed from two equivalents of trans-Re2Cl2 Characteristic absorption features of a

Re-Re dimer however were not observed in experiments with cis-Re2Cl2 We reasoned that an

added benefit of the rigid anthracene backbone is constraining the metal centers from Re-Re

bond formation a known deactivation pathway

DFT calculations were conducted to probe the likelihood of forming the neutral Re-Re

dimer or its one-electron reduced product with cis-Re2Cl2 Optimized geometries are shown in

Figure 11 Calculated distances between rhenium centers are 338 Aring for the neutral species and

352 Aring for the radical anion Solid-state structures of the corresponding dimers prepared from

Re(bpy)(CO)3Cl reduction have been characterized by X-ray crystallography52 A Re-Re bond

distance of 30791(13) Aring was found in the neutral dimer and a longer distance of 31574(6) Aring

was determined in the reduced dimer52 Given the calculated intermetallic distances for the

anthracene-based catalyst in conjunction with the spectroelectrochemical data the Re-Re bonded

dimer is likely inaccessible following reduction of cis-Re2Cl2 or limited to a transient

36

interaction These results are consistent with the improved stability observed in controlled

potential electrolyses with cis-Re2Cl2

Figure 11 Possible intermediates following reduction and chloride dissociation from cis-Re2Cl2 DFT optimized structures of a neutral dinuclear rhenium species and its one-electron reduced radical anion

It is clear from the structure of trans-Re2Cl2 and the observed reactivity that catalysis

occurs by well-established pathways known for Re(bpy)(CO)3Cl (catalytic cycles are shown in

Figure A20) including the ldquoone-electronrdquo bimolecular reductive disproportionation mechanism

at applied potentials just after the initial overlapping one-electron reductions of the Re2 complex

under anhydrous conditions Carbonate is a co-product of this pathway for trans-Re2Cl2 In the

presence of 3 M H2O or more negative potentials CO2-to-CO conversion occurs but with water

as the co-product Different behavior is observed for cis-Re2Cl2 Proposed catalytic cycles for the

two applied potential regimes -20 V and le -24 V are given in Figure 12 and Figure A21

respectively In contrast to the mononuclear catalyst and trans-Re2Cl2 the cis conformer does

not generate carbonate at applied potentials immediately following the initial overlapping one-

+endash

-

Re-Re distance 338 Aring Re-Re distance 352 Aring

37

electron reductions This difference in reactivity is presumably a consequence of the proximal

active sites being confined by hindered rotation about the anthracene bridge With this catalyst

CO2 is unable to act as an oxide acceptor by CO2 insertion into the Re-O bond of the bridging

carboxylate instead CO2 reduction is governed by protonation via Hofmann degradation of the

supporting electrolyte Along these lines Kubiakrsquos dynamic hydrogen-bonded dinuclear system

mediates reductive disproportionation at low applied potentials analogous to the ldquoone electronrdquo

pathway of Re(bpy)(CO)3Cl and consistent with its flexibility to accommodate a CO2 insertion

step5859 The proposed mechanism of cis-Re2Cl2 at more negative potentials (Figure A21) is

similar to Figure 12 but with fast catalysis coinciding with further reduction of the catalyst

38


15 Conclusion

We have described a novel ligand platform that gives access to isolable cis and trans

conformers comprised of two rhenium active sites Indeed the conformers were purified by

silica gel chromatography and characterized Consistent with its NMR spectra a crystal structure

of trans-Re2Cl2 confirmed the asymmetric orientation of Re sites on opposite sides of the

anthracene bridge In contrast the combined data (1H NMR FTIR reactivity studies) indicate

that the cis conformer is a symmetric species in which the Re sites are on the same side of the

NN

NN

Re ReOC

COOCOC CO

O CO

O

NN

NN

Re ReClOC

COOCOC CO

Cl CO

NN

NN

Re ReOC

COOCOC CO

CO

+2e -2Cl__

NN

NN

Re ReOC

COOCOC CO

O CO

HO

NN

NN

Re ReOCOC

COOCOC CO

CO

+H+

H2O

+e_

CO

+

+CO2

+H+ e_

39

anthracene backbone with their chloro ligands directed toward one another Both Re2 compounds

are active electrocatalysts for reducing CO2 to CO From mechanistic studies a pathway

involving bimetallic CO2 activation and conversion was identified for cis-Re2Cl2 whereas well-

established single-site and bimolecular pathways analogous to that of Re(bpy)(CO)3Cl were

observed for trans-Re2Cl2

Catalytic rates were measured by cyclic voltammetry for cis-Re2Cl2 trans-Re2Cl2

Re(bpy)(CO)3Cl and anthryl-Re with estimated TOFs of 353 229 111 and 192 s-1

respectively The maximum TOFs of trans-Re2Cl2 and anthryl-Re (at twice the concentration)

are approximately equal showing the effect of the pendant anthracene on catalytic activity in

comparison to Re(bpy)(CO)3Cl and with each having single-site reactivity On the other hand

the cis conformer clearly outperforms the trans conformer in terms of catalytic rate and stability

indicating the structure of cis-Re2Cl2 enables improved performance Indeed a change in

mechanism is observed at low applied potentials in anhydrous conditions where carbonate is not

formed as a co-product Synergistic catalysis by cooperative active sites in cis-Re2Cl2 are

hypothesized Spectroelectrochemical measurements indicate that cis-Re2Cl2 does not form a

deactivated Re-Re bonded species The catalyst structure delivers a unique form of protection for

catalyst longevity as intermolecular deactivation pathways are limited by the cofacial

arrangement of active sites while the rigid anthracene backbone prevents intramolecular Re-Re

bond formation

40

CHAPTER II

PHOTOCHEMICAL CO2 REDUCTION WITH MONONUCLEAR AND DINUCLEAR

RHENIUM CATALYSTS BEARING A PENDANT ANTHRACENE CHROMOPHORE

21 Introduction

For photocatalytic applications the presence of two metal centers may enable more

efficient accumulation of reducing equivalents for improved CO2 conversion1 Dinuclear

rhenium catalysts tethered together by flexible alkyl chains linking two bipyridines have been

reported for photocatalytic CO2 reduction57110These catalysts were shown to outperform their

mononuclear parent catalyst with greater durability and higher TOFs observed as the alkyl chain

was shortened However this approach lacks structural integrity and samples indiscrete

conformations in solution Other Re2 catalysts have not been studied photocatalytically or feature

ligand scaffolds that preclude intramolecular bimetallic CO2 activation and conversion58596062

Thus guidelines for designing more effective dinuclear catalysts for CO2 reduction can be

improved

In general plausible pathways for accelerated catalysis with a dinuclear complex relative

to a mononuclear analogue include (1) cooperative catalysis in which both metal centers are

involved in substrate activation and conversion or (2) one site acting as an efficient covalently-

linked photosensitizer (PS) to the second site performing CO2 reduction The key steps from

41

these hypothesized pathways are shown in Figure 13 Concerning the dual active site

mechanism (1) an intramolecular pathway may exist involving cooperative binding of the

substrate where CO2 is bridged between rhenium centers potentially increasing the basicity of

CO2 and the rate of catalysis by facilitating C-O bond cleavage and the elimination of water in

subsequent steps Intramolecular CO2 binding between metal centers is only expected for cis-

Re2Cl2 since CO2 is geometrically inhibited from interacting with both rhenium centers in trans-

Re2Cl2

Figure 13 Key steps in potential pathways (1) and (2) with dinuclear rhenium catalysts Analogous intramolecular electron transfer is expected with cis-Re2Cl2 in the PS pathway (2)

For the photosensitizer pathway (2) it is generally accepted that Re(bpy)(CO)3Cl

functions through a bimolecular pathway where one complex operates as a photosensitizer (PS)

and a second complex operates initially as a photocatalyst for the first reduction then as an

electrocatalyst which receives the second electron needed for the 2endash reduction of CO2 to CO

from a reduced PS in solution1 In this pathway cis-Re2Cl2 and trans-Re2Cl2 are predicted to

have superior reactivity to mononuclear derivatives since both dinuclear systems could utilize

N

N

N

N

Re

Re

OC

OC

OC

OCCl

OC

CO

HOO

NN

NN

Re Re0OC

COOCOC CO

Cl CON

NN

N

Re ReOC

COOCOC CO

O CO

O

N

N

N

N

Re

Re

OC

OC

OC

OCCl

CO

OC

CO

42

one Re site as a PS and the second as the catalyst thereby increasing the relative concentration of

PS near the active site This effect would be most dramatic at low concentrations where the

intermolecular reaction necessary for the monomers would be slow Higher durability at low

concentrations is known for photocatalyst systems however most rely on a high PS loading to

keep the effective concentration of PS high in the dilute solution111112 The approach pursued

here may enable a high rate of reactivity to be retained at low concentrations while promoting

increased durability

Sufficiently long-lived excited states are required for efficient solar-to-chemical energy

conversion where longer lifetimes result in more efficient excited-state quenching to generate

catalytic species One avenue to more persistent excited states in metal polypyridine complexes

is to link them with organic chromophores possessing long-lived triplet excited states where

decay pathways are strongly forbidden113-117 Anthryl substituents have served effectively as the

organic component in a variety of systems115-117 Important light absorption and excited-state

decay pathways of such systems are depicted in Scheme 2 where excited states are ultimately

funnelled downhill by internal conversion andor intersystem crossing to the anthracene-based

triplet excited state Scheme 2 also shows that the anthracene triplet state has enough energy to

produce the 1endash reduced Re complex in the presence of easily oxidized sacrificial electron donors

such as BIH

43

Scheme 2 Light absorption and excited-state electron transfer pathways in Re compounds with pendant anthracene

Beyond anthracenersquos potential to act as a triplet excited-state acceptor a rigid scaffold

for promoting cooperative bimetallic reactivity and its impact on reduced species as a large π-

system with extended delocalization the anthracene moiety also functions as a sterically bulky

group that may inhibit deleterious intermolecular catalyst deactivation pathways Indeed an

iridium-based single-component photocatalyst bearing an anthracene substituent was recently

reported for CO2 reduction with improved stability118 The steric bulk of the anthracene was

thought to deter bimolecular deactivation of the one-electron reduced catalyst and a partially

deactivated low-lying anthracene triplet state may also play a role in photoprotection118

In this context we report the photocatalytic activity and photophysical properties of the

dinuclear Re complexes shown in Figure 14 For comparison experiments employing the same

set of conditions were also performed in parallel with mononuclear chromophorecatalysts

44

Re(bpy)(CO)3Cl and anthryl-Re to disentangle the effect of more than one metal active site as

well as the possible involvement of the pendant organic chromophore in photocatalytic activity

Figure 14 Structures of Re photocatalysts studied for CO2 reduction


221 Materials and characterization



ProcessTechnology solvent purification system Acetonitrile was distilled over CaH2 and stored

over molecular sieves before use The rhenium precursor Re(CO)5Cl was purchased from Strem

and stored in the glovebox 13-dimethyl-2-phenyl-23-dihydro-1H-benzoimidazole (BIH) was

prepared according to a published procedure119 The parent catalyst Re(bpy)(CO)3Cl74

and

anthracene-functionalized rhenium catalysts cis-Re2Cl2 trans-Re2Cl2 and anthryl-Re were

prepared as previously described44 DMF was distilled with 20 of the solvent volume forecut

and 20 of the solvent volume left in the distillation flask to ensure high purity DMF was

freshly distilled and stored in a flame-dried round bottom flask under argon before being

NN

NN

Re ReClOC

COOCOC CO

Cl CON

N

N

N

Re

Re

OC

OC

OC

OCCl

Cl

OC

CO

N

NRe

OC

OCCl

CO

N

NRe

Cl

CO

CO

CO

45

discarded biweekly Triethylamine (TEA) was freshly distilled prior to use All other chemicals




protonated solvent peaks chemical shifts are reported in ppm

222 Photocatalysis equipment and methods

A 150 W Sciencetech SF-150C Small Collimated Beam Solar Simulator equipped with

an AM 15 filter was used as the light source for photocatalytic experiments Samples were

placed sim10 cm from the source the distance at which 1 sun intensity (100 mWcm2) was verified

with a power meter before each measurement Headspace analysis was performed using a gas

tight syringe with a stopcock and an Agilent 7890B Gas Chromatograph (GC) equipped with an

Agilent Porapak Q 80-100 mesh (6 ft x 18 in x 20 mm) Ultimetal column Quantification of CO

and CH4 was determined using a methanizer coupled to an FID detector while H2 was quantified

using a TCD detector All calibrations were done using standards purchased from BuyCalGas

com Formate analysis was done according to a previously reported procedure120

223 Photophysical measurement equipment and methods

Luminescence spectra were obtained with a PTI Quanta Master spectrofluorimeter

equipped with single grating monochromators and a PMT detector Spectra were not corrected

for PMT wavelength response Transient absorption spectra and excited state lifetimes were

obtained using an Applied Photophysics LKS 60 optical system with an OPOTek OPO (lt 4 ns

46

pulses) pumped by a Quantel Brilliant Laser equipped with doubling and tripling crystals

Excitation of the chromophores was typically at 420 nm using samples having an optical density

of about 05 Samples (4 mL volume) containing the Re complex were degassed by nitrogen

bubbling for 20 min immediately prior to data acquisition

224 Photocatalysis procedure

To a 17 mL vial was added BIH (005 g 024 mmol) DMF (18 mL) catalyst (as a 02

mL DMF stock solution) The solution was bubbled vigorously with CO2 for at least 15 minutes

until the solution volume reached 19 mL Then 01 mL of CO2 degassed TEA was added the

tube was sealed with a rubber septum and irradiated with a solar simulator for the indicated

time During the photolysis headspace analysis was performed at 20 40 60 120 and 240

minute time points A 300 μL headspace sample was taken with a VICI valve syringe The gas

in the syringe was compressed to 250 μL and the tip of the syringe was submerged in a

solution of diethyl ether before the valve was opened to equalize the internal pressure to

atmospheric pressure prior to injecting the contents of the syringe into the GC The entire 250 μL

sample was then injected onto the GC All experiments are average values over at least 2

reactions Turnover number (TON) values were calculated by dividing moles of product (carbon

monoxide) by moles of catalyst in solution Reported turnover frequency (TOF) values were

determined from the fastest 20 minute time period of photocatalysis within the first 40 minutes

as an estimate of the initial rate prior to significant catalyst deactivation and to account for

induction periods (ie The TON for an initial 20 minute segment was divided by 033 h to obtain

the reported TOF (h-1))

47

225 Quantum yield measurements

Measurements were conducted similarly to a method previously described121 The

number of moles of CO produced was monitored over time in 20 minute increments for the first

hour and then hourly after this time period The segment of time producing the most CO per hour

was used in the calculations for quantum yield to give the maximum quantum yield observed (1

hour time point in these cases) The photon flux in the reaction was calculated by measuring the

incident power density with a power meter (Coherent Field Mate with a Coheren PowerMax

PM10 detector) The solar simulator spectrum was cut off with a 700 nm cutoff filter since the

catalysts do not absorb light beyond 700 nm Through this method the power density was

estimated to be 573 mWcm2 The illuminated reaction area was measured to be 169 cm2 which

gives 969 mW or 969 x 10-2 Js to the sample The photon wavelength was taken as centered at

400 nm since each of the catalysts show a low energy transition shoulder in the UV-Vis

absorption spectrum at 400 nm for an energy of 497 x 10-19 J This gives 195 x 1017 photon

per second in the reaction which was used to calculate the quantum yield over the most

productive CO generating time frame via the equation

φCO = [(number of CO molecules x 2)(number of incident photons)] x 100

Anthracene + eminus (Anthracene)ndash 119864119864(119860119860119873119873119860119860119873119873minus) = -225 V vs Fc+0

(1a)

3(Anthracene) rarr Anthracene 119864119864119892119892119900119900119890119890119888119888 ~ 18 eV (1b)

BIH BIH+ + + eminus 119864119864(119861119861119861119861119861119861+119861119861119861119861119861119861) = -024 V vs Fc+0 (1c)122

48


231 Photophysical measurement

For photosensitizer-free catalysis the rhenium catalysts are initially photoexcited directly

into their long wavelength metal-to-ligand charge transfer (MLCT) absorption This is followed

by reductive quenching in the presence of a sacrificial donor to form a ligand-centered radical

anion With Re(bpy)(CO)3Cl the ligand-centered anion is delocalized on the bpy ligand prior to

Clndash dissociation55109 In the Re2Cl2 complexes the Re(bpy) units are in weak electronic

communication via the anthracene backbone (comproportionation constants (KC) of 50 were

determined electrochemically for each conformer)44 which could facilitate intramolecular

electron transfer between active sites

As will be shown below direct irradiation of the Re complexes in the presence of a

sacrificial electron donor leads to CO2 reduction to CO While photocatalysis was expected the

nature of the lowest energy excited state is different for the catalysts bearing anthracene versus

Re(bpy)(CO)3Cl In deaerated solutions (N2) all three anthracene containing complexes exhibit

luminescence in the yellowred spectral region as well as structured emission at longer

wavelengths (Figure B1) The lifetime of the yellowred emission is approximately 400 ns for the

monometallic anthryl-Re complex and 200 ns for both bimetallic Re complexes The long

wavelength emission (with vibronic components having maxima at 688-700 nm and 764-772

nm) has a double exponential decay with one component being 6-15 micros and the other 23-90 micros

(Table B1) This luminescence is completely quenched in the presence of O2 and given the

energy lifetime and O2 quenching behavior this emission almost certainly arises from an

49

anthracene-localized triplet state obtained following energy transfer from the 3MLCT excited

state123 This behavior is similar to reported metal polypyridine photo-sensitizers with pendant

anthracene (or pyrene) functionality116117124

It is not clear for these systems how the anthracene-localized triplet reacts with the BIH

electron donor to generate the reduced Re complex (quenching data shown in Figure B2)

Reduction of the anthracene-localized triplet (E0 sim 18 eV) by BIH to generate the anthracene

anion BIH cation pair is thermodynamically uphill by at least 021 V (Scheme 2)122For the

reduced Reoxidized BIH pair the energy is 136 V above the ground state (Scheme 2) and is

therefore accessible from the anthracene triplet (at 18 eV) but involves electron transfer

between the Re complex and the BIH while using the energy of the anthracene triplet Note that

an intramolecular photoredox reaction between the anthracene triplet and the Re center

(119864119864(119860119860119873119873+119860119860119873119873) sim 08 V 119864119864(119877119877119890119890(119887119887119890119890119910119910)119877119877119890119890(119887119887119890119890119910119910)minus) sim -15 V) is also endergonic Regardless of mechanism

these data clearly indicate that photoexcitation of the three anthryl Re complexes results in an

excited state that is largely localized on the anthracene as a triplet Excited-state electron transfer

between this triplet and BIH occurs (kq sim 1-5 x 107 M-1s-1 for the three complexes) to produce the

reduced complexoxidized BIH pair that following decomposition of the BIH cation radical

leaves the reduced Re complex to react with CO2 Transient absorption spectroscopy shows that

the 1endash reduced Re complexes formed by BIH photoreduction under Ar or CO2 atmosphere

exhibit no reaction over the first sim1 ms (Figure 15) This clearly indicates that disproportionation

and reaction with CO2 do not occur on this time scale

50

Figure 15 Transient absorption spectra at specified times after pulsed laser excitation (λex = 355 nm) of trans-Re2Cl2 in DMF under Ar purge (top) and trans-Re2Cl2 with BIH (001 M) under CO2 purge (bottom) No reaction of the one-electron reduced trans-Re2Cl2 complex with CO2 is evident in the first 800 micros following excitation

232 Photocatalysis

Having found that anthracene plays a significant role in the photochemistry of cis-Re2Cl2

trans-Re2Cl2 and anthryl-Re we turned to photocatalytic CO2 reduction in the presence of BIH

to understand how a dinuclear approach affects catalysis in a rigidified framework

Photocatalysis was conducted with a solar simulated spectrum and CO was the only product

observed by headspace GC analysis (Figure B3 and Figure B4)

Concentration effects were studied for all catalysts given the mechanistic implications

expected of these experiments (Figure 16 Table B2) Reported TOFs are for the fastest 20 min

51

time period within the first 40 min as an estimate of the initial rate prior to significant catalyst

deactivation Broadly comparing dinuclear complexes to mononuclear complexes significantly

higher reactivity is observed at low concentrations (005 mM) for the dinuclear complexes (158-

128 TOF h-1 105-95 TON) when compared to the mononuclear complexes (43-17 TOF h-1 34-

16 TON) If the total concentration of metal centers is held constant the mononuclear catalyst

concentration at 01 mM can be directly compared to the 005 mM dinuclear catalyst

concentration This comparison shows a similar difference in the initial rates of mononuclear

versus dinuclear catalysts with the mononuclear catalysts showing TOF values of 43-23 h-1

These results suggest a PS-based pathway is present as this explains how cis-Re2Cl2 and trans-

Re2Cl2 have comparable reactivity despite their structure while substantially outperforming the

mononuclear complexes at low concentrations where intermolecular collisions are fewer As the

concentration increases TOF and TON values converge to similar rates and durabilities for all

catalysts presumably due to intermolecular deactivation pathways that are prevalent at high

concentrations Interestingly all of the anthracene-based catalysts effectively stop evolving CO

after the first hour while Lehnrsquos benchmark catalyst continues CO production up to 2 hours In

contrast to reported systems bearing sterically bulky substituents that showed improved stability

by limiting bimolecular deactivation pathways anthryl-Re is found to be less durable (vide

infra)

52

Figure 16 Left) TON vs catalyst concentration Middle) TOF vs catalyst concentration TOF is fastest value measured within first two timepoints Right) TON for CO production vs time for 01 mM cis-Re2Cl2 01 mM trans-Re2Cl2 02 mM anthryl-Re and 02 mM Re(bpy)(CO)3Cl Conditions DMF containing 5 triethylamine 10 mM BIH irradiated with a solar simulator (AM 15 filter 100 mWcm2)

Comparing the two dinuclear catalysts trans-Re2Cl2 has higher TOF and TON values at

the lowest concentration analyzed in Figure 16 (005 mM) As the concentration increases TOF

and TON values diminish faster for the trans conformer relative to its cis counterpart

qualitatively their values follow similar trajectories The faster decrease in TOF and TON for the

trans conformer suggests that it is more susceptible to intermolecular catalyst-catalyst

deactivation pathways The performance trends for the Re2 complexes strongly suggests one

rhenium site is acting as a PS while the other performs catalysis Moreover these results indicate

intramolecular electron transfer between sites is similar for both dinuclear catalysts consistent

with their equivalent KC values44 To ensure the Re2 complexes are not photoisomerizing to the

same species in solution the catalysts were independently irradiated in d6-DMSO under N2 for

up to 8 h No appreciable interconversion of either isomer was observed by 1H NMR which

suggests both species retain their conformation over the reaction period At very low

concentrations (1 nM) where some photocatalytic systems show higher TON values111 the

highest performing catalyst trans-Re2Cl2 gives a remarkable 40000 TON for CO Notably

53

carbon monoxide from Re(bpy)(CO)3Cl at 1 nM concentration was undetectable by the GC

system used in these studies

The two mononuclear complexes show TON values at dilute concentrations that are

lower than that observed at intermediate concentrations before again decreasing to lower TONs

at high concentrations The TON values for the mononuclear catalysts peak at approximately

01-02 mM with anthryl-Re peaking at a lower concentration than Re(bpy)(CO)3Cl This

behaviour can be rationalized if the reaction is bimolecular as prior reports strongly suggest for

these types of systems109 At low concentrations a PS complex and a catalyst complex interact

less frequently and potential decomposition of either species is more competitive At

intermediate concentrations more productive reactions can occur between PS and catalyst

complexes In the high concentration regime catalyst-catalyst deactivation pathways become

competitive with CO production pathways This highlights a key difference between the

mononuclear catalysts and the dinuclear systems which retain a high effective concentration of

PS as it is covalently linked to a reactive site at low overall concentration This circumvents to

some degree the non-catalyst-catalyst deactivation mechanisms by maintaining a fast CO

production pathway Comparing TOFs for the monomers anthryl-Re has a sim2-fold faster rate of

catalysis at low concentrations A significantly higher molar absorptivity was measured at 370

nm for anthryl-Re (11100 M-1cm-1) relative to Re(bpy)(CO)3Cl (3800 M-1cm-1) and the excited

state lifetime of anthryl-Re is significantly longer than for Re(bpy)(CO)3Cl (gt 1 micros vs lt 100

ns)125 enabling a greater degree of BIH quenching These factors may explain the difference in

rates at these concentrations (Figure B5Table B1)

54

233 Quantum yield

Quantum yield estimations also show a significant difference in the catalytic behaviour of

the mononuclear versus dinuclear catalysts (Figure B6Table B2) Between 005 mM and 05

mM the dinuclear complexes have estimated quantum yields of 16-43 with higher

concentrations showing higher quantum yields In the low concentration regimes the dinuclear

catalysts have roughly double the quantum yield of the mononuclear catalysts This offers

additional evidence that pathway 2 is operable in that both dinuclear complexes have relatively

high quantum yields at low concentrations At the highest concentration evaluated (10 mM)

where the mononuclear catalyst can operate through an intermolecular PS pathway most

efficiently Re(bpy)(CO)3Cl and the dinuclear catalysts have similar quantum yields (44-46)

Based on previous work55109 and the results described here a proposed mechanism for the Re2

photocatalysts is shown in Figure 17 which illustrates a division of duties for the two active sites

and allows access to an exceptional TON value for carbon monoxide of 40 000

55

Figure 17 Proposed catalytic cycle for photochemical CO2 reduction to CO with the dinuclear Re catalysts cis-Re2Cl2 or trans-Re2Cl2 The trans conformer is shown in the specific example above

24 Conclusion

Two dinuclear Re catalysts with well-defined shape persistent structures and a

mononuclear analogue have been studied for light-driven CO2 reduction Their photocatalytic

properties have been explored in parallel with benchmark catalyst Re(bpy)(CO)3Cl

Incorporation of a pendant anthracene group on the bipyridyl ligand (anthryl-Re) had a modest

effect on the catalytic performance In contrast the Re2 catalysts perform significantly better

(sim4X higher TON) than the benchmark system when the relative concentration in rhenium is

56

held constant (01 mM dinuclear vs 02 mM mononuclear) Despite the structural differences of

cis-Re2Cl2 and trans-Re2Cl2 their initial rates are comparable with both being dramatically faster

(sim6X higher) than the mononuclear complexes which have comparable rates to each other This

suggests that the mechanism for CO2 reduction may be similar for the two dinuclear complexes

and does not require a specific spatial orientation of the Re active sites The excited-state kinetics

and emission spectra reveal that the anthracene backbone plays a more significant role beyond a

simple structural unit Evidence of an anthracene triplet state is observed and given the unlikely

event of direct reduction of the anthracene triplet state by sacrificial reductant BIH a more

complex mechanism is likely taking place beyond the Re(bpy) excitationBIH reduction kinetics

57

CHAPTER III

ISOMERIZATION BARRIERS AND RESONANCE STABILIZATION FOR THE

CONROTATORY AND DISROTATORY ISOMERIZATIONS OF NITROGEN

CONTAINING TRYCYCLO MOIETIES

31 Introduction

The effect of electron delocalization on the stabilization of transition states in some

similar pericyclic isomerizations has been reported recently126-129 In the isomerization of 1 the

lowest barrier was calculated to be 395 kcal mol-1 while the presence of a double bond in the

three carbon bridge in structure 2 provides for electron delocalization in the transition states (see

Figure 18) and the lowest allowed barrier (through TS2a) was 313 kcal mol-1 for the

isomerization electron delocalization from the double bond provided 8 kcal mol-1 of stabilization

energy

58

Figure 18 Isomerization of tricyclo[410027]heptane to cyclohepta-13-diene and tricyclo[410027]heptene to cyclohepta-135-triene

Even for unsaturated 2 itself the asymmetric position of C=C double bond leads to

various degrees of resonance effect126 For the conrotatory channels if the first bond cleaves

adjacent to the double bond in the bridge leading to TS2a the barrier is 62 kcal mol-1 lower than

for the first bond breaking nonadjacent (through TS2b) For the disrotatory channels the

difference is even greater with a barrier of 131 kcal mol-1 less when the first bond cleaves

adjacent to the double bond following the pathway to TS2a

Including a heteroatom in the bridge provides an electron lone pair which can also affect

the isomerization barriers The isomerization of 3-aza-dihydrobenzvalene to 12-dihydropyridine

59

provides an example of the stabilizing effect by delocalization from lone pair electrons127 Based

on whether the first breaking bond is adjacent or not to the N atom four different isomerization

pathways are possible For the two conrotatory pathways the barrier for the nitrogen adjacent to

the first breaking bond was 37 kcal mol-1 lower than that of nitrogen nonadjacent A more

substantial stabilization effect is seen for the two disrotatory pathways with a 91 kcal mol-1

energy difference This is illustrated in Figure 19

Figure 19 Isomerization of 3-aza-dihydrobenzvalene to 12-dihydropyridine

In a recent paper the isomerization barriers for 3-aza-benzvalene to pyridine have been

calculated128 (see Figure 20) For this structure both the lone pair on nitrogen and the π electrons

from the double bond in the bridge could provide resonance stabilization Both possible

pathways break bonds adjacent to the double bond but only one adjacent to the N atom The two

different allowed disrotatory pathways exhibited only 28 kcal mol-1 stabilization energy with the

lower barrier actually being for the bond breaking adjacent to the N atom It is due to the

symmetric position of C=N double bond in the two-member bridge leading to the almost equal

effect of electron delocalization The N atom lone pair is orthogonal to the π bonding electrons

60

and is not in a favorable geometry to delocalize For the forbidden conrotatory pathways the

stabilization is 79 kcal mol-1 with the lowest barrier being for the first bond breaking

nonadjacent to the N atom which is the result of steric effect

Figure 20 Isomerization of 3-aza-benzvalene to Pyridine To gain insight into the stabilizing effect by both π bonding electrons and lone pair

electrons simultaneously we have studied the thermal isomerization barriers for the disrotatory

and conrotatory isomerizations of 34-diazatricyclo[410027]hept- 3-ene (DATCE) to 3H-12-

diazepine (DAP1 and DAP2 enantiomers) and 345-triazatricyclo[410027]hept-3-ene (TATCE)

to 1H-123-triazepine (TAP1 and TAP2 enantiomers) The seven-member ring makes the

position of double bond asymmetric for the bicyclobutane moiety so there can be adjacent and

nonadjacent first bond cleavages The possible delocalization effect of lone pair electrons was

studied by the substitution of carbon for nitrogen For DATCE the first bond cleavage can be

adjacent or nonadjacent to the N lone pair and for TATCE a N lone pair is always adjacent but

61

the double bond can be either For assessing just the influence of a N lone pair we also included

the isomerization pathways for 34-diazatricyclo[410027]heptane (DATCA) for which only the

N lone pair is present and can be adjacent or nonadjacent to the first breaking bond The

isomerization barriers of DATCE and DATCA will be compared with tricyclo[410027]heptene

to confirm which factors would show greater contribution for molecular stabilization π bonding

electrons or lone pair electrons The isomerization of TATCE with an asymmetric position of the

N=N bond and symmetric position of nitrogen atom lone pairs offers a direct comparison of

electron delocalization effect from π bonding electrons and lone pair electrons in same molecular

structure

This paper reports the thermal isomerization of 34-diazatricyclo-[410027]hept-3-ene

(DATCE) 34-diazatricyclo[410027]heptane (DATCA) and 345-

triazatricyclo[410027]hept-3-ene (TATCE) using ab initio methods at the multireference level

These structures are shown in Figure 21 Transition state structures for each isomerization

pathway were located and both the conrotatory and disrotatory pathways have been confirmed

by intrinsic reaction coordinate computations

Figure 21 Structures of the Reactants DATCE DATCA and TATCE

62


To examine both the conrotatory and disrotatory pathways at thesame computational

level multiconfigurational self-consistent field calculations were performed All the

multireference calculations were performed using GAMESS130 The active space consisted of the

C1-C2 C1-C3 C1-C4 C2-C3 and C2-C4 σ and σlowast orbitals in the reactants (see Figure 21)

making 10 electrons in 10 orbitals MCSCF(1010) Two C-C bonds break in the bicyclobutane

moiety and two C=C double bonds form during isomerization so the active space in the

products consisted of three C-C σ and σlowast orbitals plus two π and πlowast orbitals The orbitals in the

active space were chosen after localization by Foster-Boys localization methods131 Geometry

optimizations were performed at the MCSCF(1010) level using the cc-pVDZ basis set132

Analytical gradients were employed for both geometry optimizations (first derivatives) and

harmonic frequency calculations (second derivatives) All transition structures had only one

imaginary frequency Intrinsic reaction coordinates133 were calculated to verify the connection

of the located transition state to the correct reactant and product Dynamic electron correlation

was included by performing single point energy calculations at the single state second order

MRMP134135 level at the MCSCF optimized geometries using the cc-pVDZ basis set The

resulting energies were used to compare the differences in isomerization barriers and strain

energy release Some structures were also optimized and harmonic frequencies calculated at the

CCSDcc-pVDZ level Energies for these structures were determined using single point

calculations at the CCSD(T)aug-cc-pVTZ level To compare the MCSCF results with DFT the

PBEPBE-D3 functional was used to determine the optimized geometries energies and harmonic

63

frequencies for the reactants transition states and products using the cc-pVDZ basis set For

MCSCF wavefunctions that show significant multireference character an unrestricted broken

spin symmetry wavefunction was used for the DFT calculations The coupled cluster and DFT

calculations were performed using Gaussian 16136


331 34-Diazatricyclo[410027]hept-3-ene

The isomerization of 34-diazatricyclo[410027]hept-3-ene (DATCE) to the product 3H-

12-diazapine (enantiomers DAP1 and DAP2) is discussed in this section DATCE belongs to

point group Cs with a symmetry plane containing atoms C3 N2 N1 C5 and C4 The molecular

structure of DATCE and its product DAP1 and DAP2 are illustrated in Figure 22

Figure 22 Structures of 34-diazatricyclo[410027]hept-3-ene (DATCE) and isomerization products 3H-12-diazepine (DAP1 and DAP2)

The two structures DAP1 and DAP2 are enantiomers so have the same electronic energies

The isomerization occurs by cleavage of two bonds in the bicyclobutane moiety For one

channel bond C1-C3 ruptures first and then C2-C4 second Conversely C2-C3 can break first

and then C1-C4 second Both of these possibilities lead to the same transition state due to the Cs

symmetry of the DATCE reactant Here the first breaking bond is adjacent to a nitrogen atom

64

(N2) A second channel exists in which the first breaking bond is adjacent to a carbon atom (C5)

leading to a different transition state C1-C4 can break first and then C2-C3 second or the

symmetrically equivalent C2-C4 bond breaking first and C1-C3 second Considering the

Woodward-Hoffman symmetry rules the isomerization can go through either conrotatory or

disrotatory pathways For this structure conrotatory is allowed while disrotatory is forbidden

which should have a significantly higher activation barrier In detail the isomerization of

DATCE can occur via four different pathways two leading to product DAP1 and the other two

leading to product DAP2 For clarity if the first breaking bond is adjacent to the nitrogen atom

(N2) the label ldquoNrdquo is used if the first breaking bond is adjacent to the carbon atom (C5) the

label ldquoCrdquo is used For the two controtatory pathways if the first breaking bond is adjacent to N2

the transition state is labeled NconTS1 and if adjacent to the C5 atom is labeled CconTS1

Conversely for the disrotatory pathways if the first breaking bond is adjacent to N2 the

transition state is labeled NdisTS and CdisTS if adjacent to C5The two disrotatory pathways

lead directly to the product DAP1 while the two conrotatory pathways lead to an intermediate

either NconInt or CconInt which then can isomerize to the product DAP2 A schematic diagram

for the conrotatory and disrotatory reaction channels is shown in Figure 23 while the activation

barriers are given in Table 5

65

Figure 23 Schematic diagram for the isomerization of DATCE to DAP1 and DAP2

66

Table 5 Activation barriers Ea for each pathway (kcal mol-1) Including ZPE correction

Reactiona TSa MCSCFb MRMP2c PBEPBE-D3d DATCE rarr DAP1 NdisTS 511 443 444e DATCE rarr DAP1 NdisTS 561 565 529e

DATCE rarr NconInt NconTS1 411 361 368 DATCE rarr CconInt NconTS1 413 379 393

NconInt rarr DAP2 NconTS2 174 141 168 CconIntrarr DAP2 NconTS2 178 155 307

a All geometries are optimized at the MCSCF(1010)cc-pVDZ level b The energies are calculated at the MCSCFcc-pVDZ level c The energies are calculated at the MRMP2cc-pVDZMCSCFcc-pVDZ level d The energies are calculated at the DFTcc-pVDZMCSCFcc-pVDZ level e Broken spin symmetric wave function e Broken spin symmetry wavefunction 3311 Conrotatory pathways

The transition states NconTS1 and CconTS1 which connect the reactant DATCE and

intermediates NconInt and CconInt are presented in Figure 24 while the intermediates are shown

in Figure 25


67

Figure 25 Structures for the trans double bond intermediates NconInt and CconInt for the two conrotatory pathways

The two conrotatory pathways lead to isomerization intermediates via cyclic dienes with

a trans double bond For NconTS1 the C1-C3 bond breaks first which is adjacent to N2 for

CconTS1 the C2-C4 bond breaks initially which is adjacent to C5 It can also be clearly seen

that the hydrogen on C1 for NconTS1 and C2 for CconTS1 rotates back toward the ring which

produces the trans double bond in the intermediates The trans double bond will be between

C1=C4 for NconTS1 and between C2=C3 for CconTS1 as shown in the intermediate structures

(see Figure 25) The barrier heights for the two conrotatory pathways show a slight difference of

18 kcal mol-1 at the MRMP2 level The activation energy for NconTS1 with the first breaking

bond adjacent to the N2 atom is slightly lower than for CconTS2 One explanation for the

energy difference could be electron delocalization between the bonding electrons of the N1=N2

π bond andor the lone pair electrons on the adjacent N2 atom through resulting orbital on C3

from the cleaved C1-C3 bond The lone pair orbital on N2 is orthogonal to the N=N π bond so

the only orbital with significant overlap with the p-type orbital on C3 is the π orbital The

N1=N2 double bond is slightly longer in NconTS1 being lengthened to 1220 Å from 1213 Å

68

in the DATCE reactant consistent with a slight amount of delocalization from the double bond

since C3 is adjacent The N1=N2 bond is 1215 Å in CconTS1 consistent with virtually no

delocalization since C4 is nonadjacent The two conrotatory barriers for

tricyclo[410027]heptene (structure 2) were separated by 62 kcal mol-1 Comparing the natural

orbital occupation numbers (NOONrsquos) for the orbitals comprising the first breaking bond in the

active space gives 174 for structure 2 and 182 for DATCE The slightly higher NOON value for

DATCE would mean less chance for accepting electron density through delocalization of the N2

lone pair or the π electrons consistent with a lower magnitude stabilization Structural features of

NconTS1 and CconTS1 suggest that CconTS1 is an earlier transition state than NconTS1 The

second breaking bond is 1743 Å in NconTS1 while is only 1680 Å in CconTS1 The forming

trans double bond is also longer in CconTS1 1448 Å compared to 1434 Å in NconTS1

suggesting an earlier TS for CconTS1 An earlier transition state usually means a competitively

lower activation barrier which would be consistent with a smaller separation of the activation

barriers between NconTS1 and CconTS1 (18 kcal mol-1) the barrier for NconTS1 is lowered

through delocalization while CconTS1 is lowered through steric effects manifesting as an earlier

transition state

In the transition states the H-C1-C4-H dihedral is 1694deg for NconTS1 and the H-C2-C3-

H dihedral is 1605deg in CconTS1 This illustrates the formation of the trans configuration of the

double bond is mostly complete by the transition states In the intermediate structures for the

conrotatory pathway Figure 25 the values are H-C1-C4-H = 1792deg in NconInt and H-C2-C3-H

= 1789deg in CconInt very close to the 1800deg value of a true trans structure The dihedrals

69

across the trans double bonds for the carbon atoms cannot be close to 180deg as it would make is

impossible to complete the ring They are C2-C1-C4-C5 = 1043deg for NconInt and C1-C2-C3-C4

= 1051deg for CconInt These small angles add a significant amount of strain to the seven-

membered rings The relative energies of NconInt and CconInt are both above the reactant

DATCE and the product DAP2 as listed in Table 6 DAP1 and DAP2 are enantiomers so both

have the same electronic energies and both are given the relative energy of zero in the reaction

energetics

Table 6 Relative energies including ZPE correction

Structurea MCSCFb MRMP2c DATCE 388 312 NconInt 507 456 CconInt 481 444 DAP1 0 0 DAP2 0 0

a All geometries where optimized at the MCSCF(1010)cc-pVDZ level b The geometries and energies are calculated at the MCSCFcc-pVDZ level c The energies are calculated at the MRMP2 cc-pVDZMCSCFcc-pVDZ level

The intermediates NconInt and CconInt are cyclic conjugated trienes with one trans

double bond and one cis double bond along the carbon ring moiety They are very similar in

energy and are 456 and 444 kcal mol-1 above their isomerization product DAP2 They are also

higher in energy than the DATCE reactant which is 312 kcal mol-1 above DAP2 The trans

double bond imparts a significant amount of strain energy to the intermediates more so than the

bicyclobutane moiety of the DATCE reactant

70

The intermediates NconInt and CconInt both isomerize to the product DAP2 through

trans double bond rotation through the transition states labeled NconTS2 and CconTS2

respectively which structures are shown in Figure 26

Figure 26 Structures for the transition states for trans double bond rotation of NconInt and CconInt to produce DAP2

As listed in Table 5 the activation barriers are 141 kcal mol-1 for NconTS2 and 155 kcal

mol-1 for CconTS2 As stated above the H-C1-C4-H dihedral is 1792deg in NconInt as the trans

double bond rotates toward the cis configuration the transition state (NconTS2) has a value of

1161deg for the H-C1-C4-H dihedral The NconTS2 structure has significant singlet biradical

character with NOON values of 1259 and 0741 for orbitals 25 and 26 comprising the C1=C2 π

bonding and antibonding orbitals respectively in the active space The C1-C4 bond length is

1383 Å in NconInt while it lengthens to 1496 Å in the transition state NconTS2 showing that

the double bond has broken during the rotation However the C1-C2 bond length reduces

substantially from 1499 Å to 1410 Å in NconTS2 while the cis double bond between C2-C3 has

lengthened from 1374 to 1420 Å This can be explained by delocalization of the three π

71

electrons from C1 C2 and C3 across the C1-C2-C3 bonded atoms This same behavior is found

in CconInt and CconTS2 with the rotating trans bond lengthening the distance between C2-C3

from 1379 to 1499 Å the C1-C2 single bond in CconInt shortening from 1537 to 1425 Å in

CconTS2 and the length between C1-C4 double bonded atoms increasing from 1371 to 1406

Å Delocalization of the three π electrons on C2 C1 and C4 delocalizes across the C2-C1-C4

bonded atoms

3312 Disrotatory pathways

As mentioned above there are four pathways for the controtatory channel two symmetry

related pairs which lead to two distinct transition states The same holds true for the disrotatory

pathways there are two symmetry distinct channels leading to two distinct transition states

labled NdisTS and CdisTS For NdisTS the first breaking bond is adjacent to N2 while for

CdisTS the first breaking bond is adjacent to C5 These structures are shown in Figure 27

Figure 27 Transition state structures NdisTS and CdisTS for the two disrotatory pathways The disrotatory pathways are forbidden so they should have substantially higher barriers

than the allowed conrotatory barriers this is the case with the barrier for NdisTS being 443 kcal

72

mol-1 and that for CdisTS being 565 kcal mol-1 (Table 5) The difference between the allowed

and forbidden barriers for the first breaking bond being adjacent to N2 is NdisTS - NconTS1 =

82 kcal mol-1 That for the first breaking bond adjacent to C5 is CdisTS - CconTS1 = 186 kcal

mol-1 The disparity of the differences between the allowed and forbidden barriers is reconciled

through resonance delocalization of the π electrons of the N1=N2 double bond The

wavefunctions for the disrotatory transition states NdisTS and CdisTS are highly

multiconfigurational in character as witnessed by their NOON values in the active space For

NdisTS orbitals 25 and 26 have NOON values of 1122 and 0879 respectively comprising the

two orbitals that result from the bonding and antibonding s orbitals after cleavage between C1-

C3 These values show that NdisTS is close to being a singlet biradical with a single electron on

C1 and C3 in the transition state This means that there is available electron density in that orbital

on C3 which can accept density from the π electrons from the N1=N2 double bond This

resonance delocalization lowers the energy of the transition state reducing the barrier For

CdisTS the NOON values are also near unity with the bonding and antibonding orbitals

between C2-C4 being 1089 and 0912 respectively However since the orbital on C4 is not

adjacent to the π electrons delocalization is not possible there is not a corresponding energy

stabilization of CdisTS A similar stabilization was observed with tricyclo[410027]heptene126 in

that the bond breaking adjacent to the double bond had a difference in disrotatory (forbidden)

barriers of 131 kcal mol-1 very similar to the 122 kcal mol-1 for CdisTS - NdisTS

The main structural differences in the disrotatory transition states compared to the

conrotatory ones described above are H-C1-C4-H = 111deg dihedral in NdisTS and the H-C2-C3-

73

H = 13deg dihedral in CdisTS This illustrates that the resulting double bonds will be in the cis

configuration leading directly to the DAP1 product The second breaking bond is also much

shorter in NdisTS and CdisTS compared to NconTS1 and CconTS1 making the reaction much

more asynchronous for the bond cleavages

Another interesting structural difference is the length of the N1=N2 bond in NdisTS

versus CdisTS they are 1229 Å in NdisTS and 1212 Å in CdisTS The longer N1=N2 bond in

NdisTS is consistent with electron delocalization from the π bonding orbital into the half empty

orbital on C3 slightly weakening the π bond The shorter N1=N2 bond in CdisTS is consistent

with no electron density coming from the π bonding orbital and is virtually the same length as in

the DATCE reactant (1213 Å)

3313 Intrinsic reaction coordinates

The intrinsic reaction coordinate profiles for the conrotatory and disrotatory pathways are

presented in Figure 28 The IRCs going from NconTS1 and CconTS1 back to the DATCE

reactant illustrate the nature of the bond cleavages and strain release of the bicyclobutane moiety

Going from DATCE toward the transition state the energy rises quickly as the first bond starts to

cleave Then the slope decreases substantially as the second breaking bond starts to lengthen

which allows for ring relaxation and strain energy release The slightly more pronounced

shoulder for NconTS1 is consistent with the longer bond lengths of the breaking bond pair 2515

Å and 1743 Å in NconTS1 compared to 2505 Å and 1680 Å in CconTS1 The absence of an

analogous shoulder for the distrotatory pathways is consistent with the asynchronous nature of

the reaction with the second breaking bond still largely intact minimizing strain release at the

74

transition state This would make the disrotatory transition states higher in energy consistent with

their forbidden classification


332 34-Diazatricyclo[410027]heptane

The structure of 34-diazatricyclo[410027]heptane (DATCA) and its isomerization

products 23-dihydro-1H-12-diazepine (DHDAP1 and DHDAP2) are presented in Figure 29 In

this reactant structure there is a single bond between the two nitrogen atoms so there are no

π electrons available to stabilize the transition states - only the lone pair electrons on nitrogen

DATCA belongs to point group C1 so there are eight total reaction channels four conrotatory

and four disrotatory A similar naming scheme for the DATCE reaction described above is used

for the first breaking bond being either adjacent to the N2 atom or the C5 atom In this case due

75

to the lack of a symmetry plane breaking bonds C1-C3 then C2-C4 leads to one transition state

(NconTS1prime or NdisTSprime ) and breaking bonds C2-C3 then C1-C4 leads to a different one

(NconTS1Prime or NdisTSPrime ) Conversely bonds C1-C4 then C2-C3 leads to CconTS1prime or CdisTSprime

and breaking bonds C2-C4 then C1-C3 leads to CconTS1Prime or CdisTSPrime The four allowed

conrotatory channels lead to cyclic intermediates with a trans double bond which can form the

DHDAP1 or DHDAP2 product through trans double bond rotation The structural isomers

DHDAP1 and DHDAP2 differ only by a few kcal mol-1 in electronic energy At the MRMP2

level DHDAP1 is the lowest energy structure by 11 kcal mol-1 However at the CCSD(T)aug-

cc-pVTZCCSDcc-pVDZ level DHDAP1 is the lowest energy structure by 02 kcal mol-1

These values are listed in Table 8 A schematic diagram for the conrotatory and disrotatory

reaction channels is shown in Figure 30 while the activation barriers are given in Table 7

Figure 29 Structures of 34-diazatricyclo[410027]heptane (DATCA) and isomerization products 23-dihydro-1H-12-diazepine (DHDAP1 and DHDAP2)

76

Figure 30 Schematic diagram for the isomerization of DATCA to DHDAP1 and DHDAP2

Table 7 Activation barriers Ea for each pathway (kcal mol-1) including ZPE correction

Reactiona TSa MCSCFb MRMP2c PBEPBE-D3d DATCA rarr DHDAP2 NdisTSprime 541 523 586e DATCA rarr DHDAP2 NdisTSPrime 518 495 543e

77

DATCA rarr DHDAP1 CdisTSprime 554 567 752e DATCA rarr DHDAP1 CdisTSPrime 552 573 715e DATCA rarr NconIntprime NconTS1prime 447 433 469 DATCA rarr NconIntaPrime NconTS1aPrime 414 379 407 DATCA rarr CconIntprime CconTS1prime 399 374 412 DATCA rarr CconIntPrime NconIntaPrimerarr NconIntbPrime

CconTS1Prime NconTS1bPrime

446 02

433 17

489 19

NconIntprime rarr DHDAP1 NconTS2prime 208 159 247 NconIntbPrimerarr DHDAP1 NconTS2Prime 165 125 249 CconIntprime rarr DHDAP2 CconTS2prime 184 141 251 CconIntPrime rarr DHDAP2 CconTS2Prime 200 163 273

a All geometries are optimized at the MCSCF(1010)cc-pVDZ level b The energies are calculated at the MCSCFcc-pVDZ level c The energies are calculated at the MRMP2cc-pVDZMCSCFcc-pVDZ level d The energies are calculated at the DFTcc-pVDZMCSCFcc-pVDZ level e Broken spin symmetric wave function Table 8 Relative energies including ZPE correction

Structurea MCSCFb MRMP2c CCSD(T) d DATCA 433 310 308 DHDAP1 0 0 0 DHDAP2 16 11 02 NconIntprime 466 408 NconIntaPrime 806 649 626 CconIntprime 447 391 CconIntPrime 501 446

a All geometries where optimized at the MCSCF(1010)cc-pVDZ level b The geometries and energies are calculated at the MCSCFcc-pVDZ level c The energies are calculated at the MRMP2 cc-pVDZMCSCFcc-pVDZ level d The energies are calculated at the CCSD(T)aug-cc-pVDZCCSDcc-pVDZ level

3321 Conrotatory pathways

There are four conrotatory channels for the ring opening leading to the DHDAP1 or

DHDAP2 products and can be classified as whether the first breaking bond is adjacent to N2 or

C5 If the first bond breaks adjacent to N2 it is useful to note the position of the H atom bonded

78

to N2 relative to the first breaking bond If the C1-C3 bond breaks first the H-N2-C3-C1

dihedral is positive so that the H on N2 is on the same side of the dihedral looking down N2-C3

if the C2-C3 bond breaks first the H-N2-C3-C2 dihedral is negative so that the H on N2 is on the

opposite side of the dihedral looking down N2-C3 If the first bond breaks adjacent to C5 it is

useful to note the position of the H atom bonded to N1 If the first breaking bond is C2-C4 then

the H of N1 is on the same side of the dihedral about C5-C4 and if the first breaking bond is C1-

C4 the H of N1 is on the opposite side of the dihedral about C5-C4 For notation a single prime

is used for the positive dihedral angle while a double prime is used to denote the negative

dihedral angle

The two transition states for the first breaking bond adjacent to C5 are shown in Figure

31 CconTS1prime is an earlier transition state per the shorter breaking bonds (C2-C4 and C1-C3) and

the longer C2-C3 bond (compared to C1-C4 C2-C3 and C1-C3 in the other TS respectively)

which are the two breaking bonds and the forming trans double bond The barrier for NconTS1prime

is also lower 374 vs 433 kcal mol-1 also consistent with an earlier transition state

Figure 31 Structures of transition states CconTS1primeand CconTS1Prime

79

The transition states for the initial bond cleaving adjacent to the N2 atom are shown in

Figure 32 and Figure 33 The transition state barrier leading to NconTS1prime is actually higher than

the analogous CconTS1prime showing that the lone pair electrons did not lower the barrier through

delocalization with the orbitals resulting from cleavage of the C1-C3 bond steric effects are the

most important here The NOON values are similar for both transition states being 1766 and

0237 for CconTS1prime and 1774 and 0234 for NconTS1prime Having NOON values this close to 2 and

0 means there is little opportunity for delocalization of the N2 lone pair into a partially filled

orbital on C3 For the other conrotatory channel there was an unexpected intermediate found on

the potential energy surface The structure of the transition state NconTS1Primea appeared to be

consistent with the other conrotatory channels described above and lead to the cyclic trans

double bond intermediate However following the IRC led to the reactant but in the forward

direction led to a minimum with a geometry very similar to the transition state NconIntaPrime (Figure

33) The NOON values of the transition state NconTS1aPrime are 1786 and 0216 for the orbitals

comprising the first breaking bond so single reference coupled cluster calculations should be

able to adequately describe the wavefunction In order to get the most accurate energies and the

best description of the PES the geometry of NconTS1aPrime was optimized at the CCSDcc-pVDZ

level The harmonic frequencies were also determined at this level (numerical second

derivatives) and one imaginary frequency was present confirming this as a transition state Single

point energies were calculated at the CCSD(T)aug-cc-pVTZCCSDcc-pVDZ level for the

minima and transition states for this channel The barrier from DATCA to NconTS1aPrime is 379

kcal mol-1 at the MRMP2 level and 405 kcal mol-1 at the CCSD(T) level Comparison of this TS

80

(NconTS1aPrime) to the other conrotatory one (NconTS1prime) shows that NconTS1aPrime is a much earlier

transition state The first breaking bond C2-C3 is 2216 Å in NconTS1aPrime while that for C1-C3 in

NconTS1prime is 2518 Å The second breaking bond C1-C4 in NconTS1aPrime is 1554 Å while the C2-

C4 bond in NconTS1prime is much longer at 1715 Å The C2-C4 bond of NconTS1aPrime will become a

trans double bond in the cyclic intermediate and it is 1505 Å The C1-C3 bond of NconTS1aPrime

will become a trans double bond in the cyclic intermediate and it is shortened to 1455 Å The

shorter breaking bonds and longer forming double bonds confirm the TS on an much earlier

portion of the PES

Figure 32 Structure of transition state NconTS1prime

Figure 33 Structures of NconTS1aPrime NconInt aPrime and NconTS1bPrime

81

The structure of the intermediate NconInt aPrime is very similar to the conrotatory transition

states and to get a second confirmation that it was actually a minimum the geometry from the

end of the IRC calculation was optimized and the harmonic frequencies computed at the MSCSF

level they were all real values The calculation was repeated at the CCSDcc-pVDZ level and

the geometries optimized and harmonic frequencies determined all real frequencies were present

at this level also NconInt aPrime is just 48 kcal mol-1 lower than NconTS1aPrime at the MRMP2 level

and 87 kcal mol-1 lower at the CCSD(T) level consistent with the very similar structures of the

NconTS1aPrime and NconIntaPrime An explanation for the NconIntaPrime intermediate is the availability of

the N2 lone pair to delocalize into orbital 27 resulting from the cleavage of the C2-C3 bond in

NconTS1aPrime These two orbitals are shown in Figure 34 Orbital 27 is localized to C3 and is

eclipsed with orbital 20 comprising the N2 lone pair Orbital 27 of the active space has a NOON

of 0216 so it can readily accept electron density The same overlap between orbitals 20 and 27 is

available in NconIntaPrime The shortening of the N2-C3 bond in 1380 in NconIntaPrime is consistent

with additional bonding overlap between N2 and C3 In addition the C1-C3 bond is also

shortened having a value of 1404 Å

Figure 34 Densities for orbital 20 (p-type on C2 and C3) and orbital 27 (lone pair on N2) of NconTS1Prime and NconIntaPrime

82

The dihedral angle between the overlap of orbitals 20 and 27 can be approximated by the

H-C3-N2-H dihedral angle the N2 atom is tetrahedral and the C3 is trigonal planar in

NconTS1aPrime and NconIntaPrime Therefore a H-C3-N2-H=30deg would be a totally eclipsed geometry

for the p orbital on C3 (27) and the sp3 lone pair orbital on N2 It is 703deg in the transition state

NconTS1aPrime signifying partial overlap between the two being offset by approximately 40deg In the

intermediate NconIntaPrime the H-C3-N2-H dihedral is only 311deg signifying a totally eclipsed

geometry giving substantial overlap between orbitals 20 and 27

The C1-C4 bond in NconIntaPrime is also lengthened to 1634 Å allowing the C2-C4 trans π

bond to initiate formation This stabilization allows for the structure to be a minimum of the PES

The N2 lone pair orbital is not eclipsed with orbital 27 in the other conrotatory transition state

NconTS1prime so stabilization is not possible so there is no analogous intermediate formed

The transition state from NconIntaPrime to the cyclic trans double bond intermediate is

labeled NconTSbPrime and shown in Figure 33 The barrier from NconTS1aPrime to NconTS1bPrime is just 17

kcal mol-1 at the MRMP2 level and 37 kcal mol-1 at the CCSD(T) level The minimum occupied

by NconTS1aPrime is very shallow with the further release of strain energy going to NconIntbPrime the

main character of this portion of the PES Basically the transition state encompasses the

cleavage of the second bond to break the C1-C4 bond lengthens to 1760 Å The C2-C4 length

shortens in NconTS1bPrime as the double bond continues forming The barrier for the transition state

NconTS1bPrime was determined at the MRMP2 and CCSD(T) levels since the barrier is so small and

the wavefunction is mostly single configurational having NOONrsquos of 1866 and 0122 for the

orbitals comprising the C1-C4 breaking bond

83


There are four disrotatory transition states possible for DATCA bond C1-C3 (NdisTSprime)

or bond C2-C3 (NdisTSPrime) breaking first or bond C1-C4 (CdisTSprime) or C2-C4 (CdisTSPrime) breaking

first The transition state structures are shown in Figure 35 Both CdisTSprime and CdisTSPrime have

almost identical barriers with no possibility of overlap of the N2 lone pair onto C3 consistent

with the barriers being the highest NdisTSprime and NdisTSPrime have lower barriers by 44 and 72 kcal

compared to CdisTSprime For these two transition states the lone pair on N2 can delocalize into

orbitals 26 and 27 on C3 consistent with the lower barrier heights The NOONrsquos are 1170 and

0833 for orbitals 26 and 27 of NdisTSprime and 1231 and 0770 for NdisTSPrime The lone pair is in

phase for overlap relative to both orbitals 26 and 27 on C3 and these two orbitals are basically

half filled (singlet biradical) The N2-C3 bond length is 1441 Å in the DATCA reactant and

shortens to 1406 and 1409 Å in the two transition states also consistent with delocalization of

the N2 lone pair across the N2-C3 bond The disrotatory transition states are more asynchronous

than the conrotatory ones with the second breaking bond much shorter here The H atom on C1

or C2 also points away from the ring in the configuration to form a cis double bond in the

DHDAP products

84

Figure 35 Structures of transition states for the disrotatory channel of DATCA


The IRC curves for the four conrotatory channels are shown in Figure 36 The

intermediate NconIntaPrime is labeled and the very shallow minimum between it and intermediate

NconIntbPrime is apparent The IRC plots connect the DATCA reactant to the trans bond

intermediates and subsequently to the DHDAP1 and DHDAP2 products The disrotatory IRC

curves are shown in the Figure C1 They contain the single transition state and directly connect

the DATCA reactant to the DHDAP1 and DHDAP2 products

85

Figure 36 Intrinsic reaction coordinates for the four conrotatory channels for DATCA isomerization

333 Orbital stabilization

The disparity between the activation energies among the conrotatory and disrotatory

channels is due to steric and resonance effects This section will discuss the stabilization of some

transition states due to delocalization of the π electrons of the N=N double bond and

delocalization of the lone pair on the N atom

For the DATCE reactant transition states and DAP1 and DAP2 products the active space

consists of orbitals 21-30 Looking at the MCSCF natural orbitals 18 and 20 consist of a

combination of the two lone pairs of the N atoms and orbital 19 consists of the N=N π bonding

86

orbital in each structure The two disrotatory pathways show one barrier significantly lower

NdisTS is 82 kcal mol-1 lower than CdisTS Cleavage of the C1-C3 bond can lead to transition

state NdisTS as shown in Figure 37 The C1-C3 bonding and antibonding orbitals of the reactant

DATCE are now represented by orbitals 25 and 26 in the active space which are π type orbitals

on C1 and C3 The NOONrsquos for orbitals 25 and 26 are close to 1 so can accept significant

electron density The NOON values for orbitals 25 and 26 for NdisTS are 1112 and 0879

respectively In comparison the NOON values for orbitals 25 and 26 for the CdisTS transition

state are 1089 and 0912 in this transition state the breaking bond is not adjacent to the N=N π

bond As shown in Figure 37 the half empty orbitals 25 and 26 on C3 are both in phase with

the π orbital on N1=N2 The higher NOON value for orbital 25 in NdisTS than for CdisTS

(1122 vs 1089) suggest that orbital 25 of NdisTS accepts electron density from the N=N π

bond The increased occupation number for orbital 25 would lower its energy compared to

orbital 26 which would result in a reduction of the NOON value for orbital 26 This is reflected

in the NOON value of 0879 compared to 0912 in the unstabilized CdisTS The delocalization of

the π electrons into orbital 25 would lower the electronic energy of the transition state lowering

the activation barrier

87

Figure 37 Densities for orbital 19 (p-bonding on N1=N2) orbital 25 (p-type on C1 and C3) and orbital 26 (p-type on C1 and C3) from the MCSCF natural orbitals for NdisTS1

Cleavage of the C1-C3 bond can also result in transition state NconTS1 shown in Figure

38 Orbitals 25 and 26 of the active space are the p-type orbitals resulting from the cleaved C1-

C3 bonding and antibonding orbitals The phases of 25 and 26 are opposite on C3 but the same

on C1 The density from orbital 19 on N2 and orbital 25 on C3 are opposite in phase so there is

an antibonding overlap between N2 and C3 for these two orbitals the N=N π bonding orbital

(19) and the p-type orbital on C3 (25) Orbital 25 has a NOON value of 1815 close to being

doubly occupied However orbital 26 has a NOON value of 0195 and is in phase with the N=N

p bond Orbital 26 being mostly empty and in phase with the N=N p orbitals can accept electron

density from the N=N π bond however since orbital 26 is mostly unoccupied its energy will be

significantly higher than the N=N π bonding orbital (19) and the overlap will be decreased on

that energetic standpoint This smaller stabilization energy follows the smaller 18 kcal mol-1

barrier lowering for NconTS1 compared to CconTS1

88

Figure 38 Densities for orbital 19 (p-bonding on N1=N2) orbital 25 (p-type on C1 and C3) and orbital 26 (p-type on C1 and C3) from the MCSCF natural orbitals for NconTS1

The DATCA reactant does not have N=N π bond but the N atom lone pairs can

participate in delocalization and stabilize the transition states For the DATCA reactant transition

states and DHDAP1 and DHDAP2 products the active space consists of orbitals 22-31 For the

MCSCF natural orbitals 20 and 21 are combinations of the N atom lone pairs Transition state

NdisTSPrime has the lowest barrier of the four disrotatory channels and is shown in Figure 39

Orbital 20 consists of the lone pair on N2 while orbitals 26 and 27 are the remnants of the

cleaved C1-C3 bonding and antibonding orbitals in the DATCA reactant Orbital 26 consists of

two p-type orbitals on C3 and C2 which are in phase with each other while orbital 27 consists of

two p-type orbitals on C3 and C2 which are opposite phases However for orbitals 26 and 27 the

p-type orbital on C3 are both in phase with the N2 lone pair orbital The NOON for orbital 26 is

1231 while that for orbital 27 is 0770 making orbital 26 lower in energy Electron density from

the lone pair on N2 can delocalize into orbitals 26 and 27 since they are both in phase with the

lone pair orbital but delocalization will be more efficient with the lower energy orbital 26

Resonance between orbitals 20 and 26 would require that delocalization into orbital 26 would

89

lower its energy and raise its occupation number This would result in a higher occupation

number for orbital 26 and a lower one for orbital 27 Comparing the NOONrsquos for this transition

state with the two transition states where delocalization is not possible (CdisTSprime and CdisTSPrime)

shows that orbital 26 on NdisTSPrime is 1231 compared to 1059 and 1004 on CdisTSprime and CdisTSPrime

respectively For orbital 27 the NOON value is lower on NdisTSPrime 0770 versus 0943 for

CdisTSprime and 0997 for CdisTSPrime For the two transition states CdisTSprime and CdisTSPrime the cleaved

bond is not adjacent to a nitrogen lone pair and no delocalization is possible so the NOONrsquos are

much closer to 10 The barriers for these two transition states are higher as a result of their

higher electronic energies and their NOON values reflect almost pure singlet biradical character

Stabilization is also possible for transition state NdisTSprime since orbital 26 is in phase with the N2

lone pair orbital and it also has a lower barrier than those for CdisTSprime and CdisTSPrime The 59 kcal

mol-1 difference in the barriers for the CconTSprime and CconTSPrime transition states is most likely due

to steric effects and is represented in the IRCrsquos in which the lower barrier is for the earlier

transition state

90

Figure 39 Densities for orbitals 20 (lone pair on N2) 26 (p-type on C2 and C3) and 27 (p-type on C2ndashC3) from the MCSCF natural orbitals for NdisTS1Prime


In order to understand the relative stabilizing effects of the N=N π electrons versus the N

lone pair electrons we also looked at the isomerization of 345-triazatricyclo[410027]hept-3-

ene (TATCE) to the 1H-123-triazepine (TAP1 and TAP2 enantiomers) The TATCE reactant

and TAP1 and TAP2 products are shown in Figure 40 The TATCE structure has both the N=N π

bond and a sp3 hybridized N atom lone pair in the same molecule Since it is the disrotatory

transition states that are singlet biradical in character with two orbital NOONrsquos close to 10 we

present these since they are the most efficient in accepting electron density and reflecting a lower

activation barrier

91

Figure 40 Structures of 345-triazatricyclo[410027]hept-3-ene (TATCE) and isomerization products 1H-123-triazepine (TAP1 and TAP2 )

The first breaking bond can be adjacent to N1 and the N=N π bond or to N3 and the N3

atom lone pair If the C1-C3 bond breaks first the transition state is labeled N1disTS1 and if

C2-C3 breaks first it is labeled N1disTS2 If the C1-C4 bond breaks first the transition state is

labeled N3disTS1 and if the C2-C4 bond breaks first it is labeled N3disTS2 The transition state

structures are given in Figure 41 and the activation barriers are given in Table 9 Each barrier is

below 50 kcal mol-1 lower than the 57 kcal mol-1 for the CdisTS structures for DATCE and

DATCA given above In addition the two channels for which the π electrons are adjacent to the

breaking bond have lower barriers than the two with the N3 lone pair adjacent to the breaking

bond This suggests that the stabilization energy is greater through the π electrons than through

the N lone pair consistent with the bonding picture of double bond electrons being more

delocalized across two atoms than a lone pair more confined to a single atom

92

Figure 41 Structures of the disrotatory transition states for the TATCE to TAP1 and TAP2 isomerizations


Reactiona TSa MCSCFb MRMP2c TATCE rarr TAP2 N1disTS1 500 423 TATCE rarr TAP1 N1disTS2 512 444 TATCE rarr TAP1 N3disTS1 507 474 TATCE rarr TAP2 N3disTS2 522 491

aAll geometries are optimized at the MCSCF(1010)cc-pVDZ level bThe energies are calculated at the MCSCFcc-pVDZ level cThe energies are calculated at the MRMP2cc-pVDZ MCSCF cc-pVDZ level

93

35 Conclusion

The thermal isomerizations of 34-diazatricyclo[410027]hept-3-ene 34

diazatricyclo[410027]heptane and 345-triazatricyclo[410027]hept-3-ene were modeled

using computational chemistry In order to get a consistent picture of the energies and potential

energy surfaces for both the allowed and forbidden pathways MCSCF calculations were used

CCSD(T) energies were also computed where single reference wavefunctions were adequate for

a description of the molecules

The lowest allowed barrier for the isomerization of DATCE is 361 kcal mol-1 lower than

the 395 kcal mol-1 for the all carbon tricyclo[410027]heptane The energy reduction of the

barrier is proposed to be due to electron delocalization of the N=N π bond in DATCE in the

transition state and steric effects It is difficult to apportion the individual contribution of each

but compared to structure 2 which had a 62 kcal mol-1 lower barrier for the first cleaved bond

being adjacent to the C=C double bond the difference for DATCE is only 18 kcal mol-1

Likewise the lowest forbidden barrier for DATCE isomerization is 443 kcal mol-1 also with the

cleaved bond adjacent to the N=N double bond stabilized by π electron donation to the half

filled orbital left due to the cleaved C-C bond This barrier is 122 kcal mol-1 lower than the other

forbidden one where the cleaved bond in non-adjacent to the N=N double bond - no π electron

donation possible The transition states for the forbidden pathways have singlet biradical

character with NOONrsquos of two orbitals close to 12 and 08 The stabilization of the forbidden

pathways is greater than the allowed pathways due to this singlet biradical character For the

allowed conrotatory pathways the NOONrsquos for the two resulting orbitals of the cleaved C-C

94

bond are around 175 and 025 so they are not as effective in the resonance stabilization with the

N=N π bonding orbital

The DATCA structure does not have a N=N double bond but does have an N atom lone

pair for possible delocalization and stabilization of the transition states The isomerization of

DATCA shows results similar to DATCE mentioned previously the four allowed barriers range

from 374 to 433 kcal mol-1 but the two lowest values (374 and 379 kcal mol-1) are for an

adjacent and nonadjacent bond cleavage to the N atom lone pair It appears both steric and

delocalization effects are present The forbidden pathways follow a more consistent pattern with

the two lowest barriers belonging to the pathways where the first C-C bond cleaves adjacent to

the N atom lone pair This suggests that delocalization of the N atom lone pair into the half-filled

orbital on the adjacent carbon atom lowers the energy of the transition state

Since delocalization is more easily delineated in the forbidden pathways we also looked

at those for the isomerization of TATCE in which a C-C bond cleaves either adjacent to a N=N

double bond or an N atom lone pair The lowest barriers were for the cleaved bond being

adjacent to the N=N double bond consistent with the π electrons being able to delocalize more

effectively than a lone pair on a single atom

One allowed pathway for DATCA formed an intermediate with a structure very close to

the transition state The barrier is only 05 kcal mol-1 higher than the lowest allowed barrier so

would be kinetically competitive The minimum on the PES was described by bonding between

the N atom lone pair orbital and the resulting p-type orbital on the adjacent C atom from the

bond cleavage The minimum has only a 17 kcal mol-1 barrier leading to the normal trans double

95

bond intermediate of the isomerization pathway The allowed pathways from DATCE and

DATCA form a ring with a trans double bond rotation of this double bond from the trans to cis

orientation occurs with a barrier between 125 and 163 kcal mol-1 The release of strain energy

caused by the trans double bond orientation in the seven-membered ring lowers the barrier of the

double bond rotation significantly from that of a non-strained counterpart such as ethylene

A previous paper compared activation energies of MRMP2 and various DFT functionals

for wavefunctions with significant multiconfigurational character137 The PBEPBE-D3 functional

gave activation barriers close to those of MRMP2 for both the allowed and forbidden pathways

For the DATCE isomerization the PBEPBE-D3 functional gave energies very close to the

MRMP2 results except for the trans double bond rotations which go through transition states

with significant singlet biradical character For the DATCA isomerization this functional gave

good results for allowed pathways and for only two of the four forbidden ones The activation

barriers were close to 14 and 19 kcal mol-1 higher than the MRMP2 results for those two

forbidden pathways The trans double bond energies were also about 10 kcal mol-1 higher than

the MRMP2 results

96

CHAPTER IV

THE AB INITIO STUDY OF THERMAL ISOMERIZATION OF BENZVALENE TO

BENZENE AND BENZVALYNE TO BENZYNE

41 Introduction

Benzvalene (tricyclo[310026]hex-3-ene) was first reported in 1967 by Wilzbach etc as

a photoproduct of benzene138 and is an energy-rich cyclic compound due to its highly strained

structure The low stability of benzvalene along with extraordinary reactivity exhibits diverse

chemistry The kinetic stability at room temperature138( half-life of about 10 days in isohexane)

also makes benzvalene an interesting structure The investigation of thermal barriers for

conversion of high energy-density benzvalene to the stable benzene isomer could pave the way

for exploration of benzene-benzvalene MOST for energy storage and release The activation

energy for isomerization of benzvalene to benzene via a biradical transition state was initially

calculated to be 215 kcal mol-1 by MINDO139 showing a barrier 52 kcal mol-1 lower than the

experimental thermolysis in n-heptane140 The activation barrier for benzvalene isomerization has

also been calculated to be 399 kcal mol-1 using ab initio methods at the MP36-31GHF6-

31G level141 and 277 kcal mol-1 using DFT with the B3LYP functional142 Other theoretical

studies focused on the heat of formation and strain energy of benzvalene at single configuration

self-consistent field6-31G level143 and G2(MP2SVP) level144 Previous studies of similar

97

tricyclco compounds showed multireference calculations were required due to the

biradical character of the transition states especially for disrotatory pathways46126-

129137However there is no multi-reference self-consistent field (MCSCF) report to revisit the

isomerization of benzvalene to benzene and a multi-reference wave function should be a better

description of the biradical nature of transition states

The pyrolysis of benzene would generate another chemically interesting six-member ring

compound benzyne via C-H fission145146 The peculiar chemical structure of benzyne makes it an

essential tool in synthetic chemistry147 Besides studies reveal that benzyne plays a vital role in

the formation of polycyclic aromatic hydrocarbons(PHAs)148149 PHAs produced from

combustion of fuels pose considerable damage to human health Therefore the benzyne structure

has been the subject of extensive theoretical studies Current calculations focus on the

thermochemistry150151 fragmentation pathway152153 and isomerization pathway between o-

benzyne p-benzyne and m-benzyne152-154 Inspired by the remarkable reactivity of benzvalene

we are curious about the analogous valence isomer of benzyne To our knowledge benzvalyne

(tricyclo[310026]hex-3-yne) the analogous structure of benzvalene was only mentioned once

in the literature and that in the study of triafulvene (bicyclopropenylidene)155

Herein we would like to investigate the isomerization pathways of benzvalene to

benzene and benzvalyne to benzyne at the MCSCF calculation level


To obtain a highly accurate description of the wave function geometry optimizations

including benzvalyne benzvalene benzyne and benzene were performed at the multi

98

configuration self-consistent field (MCSCF) level using the cc-pVTZ basis set132 performed by

GAMESS130 For benzvalene four σ and σ orbitals consisting of the C1-C3 C1-C4 C2-C3 and

C2-C4 bonds in the bicyclobutane moiety and one π and π of the C5=C6 double bond were

localized by the Foster-Boys method36 The resulting five occupied and five virtual orbitals made

the MCSCF (1010) subset for the complete active space calculation Two C-C bonds broke in

the bicyclobutane moiety and two C=C double bonds formed during isomerization so the active

space in the product benzene consisted of two C-C σ and σ orbitals plus three C=C π and π

orbitals For benzvalyne four σ and σ orbitals in the bicyclobutane moiety and the in-plane and

out-plane π and π were localized also by the Foster-Boys method The resulting six occupied

and virtual orbitals made the MCSCF (1212) subset for complete active space calculation For

benzyne the full conjugated systems including two σ and σ orbitals and four π and π made

MCSCF(1212) Analytical gradients were employed for both geometry optimizations (first

derivatives) and harmonic frequency calculations (second derivatives) All transition structures

had only one imaginary frequency Intrinsic reaction coordinates were calculated to verify the

connection of the located transition state to the correct reactant and product133 Dynamic electron

correlation was included by performing single point energy calculations at the single state second

order MRMP level at the MCSCF optimized geometries using the cc-pVTZ basis set134135 The


energy release

99


431 Benzvalene

The thermal isomerization of benzvalene to benzene is discussed in this section The

molecular structures of benzvalene and benzene are shown in Figure 42 The isomerization

process involves the rupture of two nonadjacent C-C σ bonds in the bicyclobutane moiety and

the formation of a conjugated π cyclo-compound Benzvalene belongs to point group C2v with

the C1-C2 bond bisected by the plane containing the C3 C4 C5 and C6 atoms The

isomerization reaction involved cleavage of a C-C bond pair this can be C1-C3 C2-C4 C1-C4

C2-C3 C1-C4 C2-C3 C2-C4 C1-C3 Any four of these possibilities will lead to the same

transition state due to the C2v symmetry of benzvalene Therefore there is only one disrotatory

and one conrotatory pathway given the Woodward-Hoffman symmetry rules The transition

states for the disrotatory and conrotatory pathways are labeled as disTS and conTS respectively

The schematic energy diagram for the isomerization pathways are presented in Figure 43

Figure 42 Structures of benzvalene and and isomerization product benzene

100



Features of the disrotatory transition state are presented in Figure 44 The activation

barrier of disTS has been determined to 206 kcal mol-1 at the MRMP2 level shown in Table 10

For comparison with the experimental value the activation barrier was corrected to 187 kcal

mol-1 at 298K using unscaled harmonic vibrational frequencies It is 80 kcal mol-1 lower than the

experimental barrier obtained in n-heptane In comparison the barrier height at 298K was

previously reported to be 399 kcal mol-1 at the MP36-31GHF6-31G level141 and 293 kcal

mol-1 at the B3LYP level142 they are instead higher than the experimental barrier In contrast to

similar tricyclo compounds 46126-129137 the transition state for the disrotatory pathway is mostly

single configurational in character as witnessed by the natural orbital occupation numbers

(NOONrsquos) in the active space For disTS orbital 21 (p orbital on C1 and C3) and orbital 22 (p

101

orbital on C1 and C3) have NOON values of 1711 and 0295 This uncustomary non biradical

transition state was also found by Bettinger etc at the B3LYP CCSD and CCSD(T) levels142

The initial breaking bond C1-C3 has a length of 2353 Å in the transition state while the second

breaking bond length is 1668 Å The 0685 Å difference in the two bond lengths is an indicator

of a less asynchronous progress The double bond between C5 and C6 in reactant benzvalene

tends to transfer to adjacent C3 and C6 in disTS The C3-C6 bond length shortens from 1500 Å

in benzvalene to 1366 Å in disTS while the C5-C6 bond lengthens from 1338 Å in benzvalene

to 1409 Å in disTS This suggests the C5=C6 double bond is not inert as it participates in

breaking the bicyclobutane moiety The C4-C5 bond length also shrinks to 1423 Å in disTS

(The p orbital should on C3 but now on C5)

Figure 44 Transition state structures disTS and disTSback for the two disrotatory pathways

102


Reactiona TSa MCSCFb MRMP2c benzvalene rarr benzene disTS 258 206 benzvalene rarr benzvalene disTSback 300 298 benzvalene rarr conInta conTS1a 291 268 conInta rarr conIntb conTS1a 96 36 conIntb rarr benzene conTS2 27 47

a All geometries are optimized at the MCSCF(1010)cc-pVTZ level b The energies are calculated at the MCSCFcc-pVTZ level c The energies are calculated at the MRMP2cc-pVTZMCSCFcc-pVTZ level

Remarkably the transition state disTSback with singlet biradical nature was found for a

concerted disrotatory pathway For disTSback orbital 21 (p orbital on C1 and C3) and

orbital 22 (p orbital on C1 and C3) have NOON values of 1039 and 0962 However the

intrinsic reaction coordinate from disTSback leads to benzvalene in both the forward and reverse

directions The isomerization occurs by breaking C1-C3 bond in reactant benzvalene and

forming C1-C5 bond in product benzvalene This is apparently a biradical transition state in

which one C-C bond cleaves and reforms to restore the benzvalene reactant The two disrotatory

pathways of benzvalene are presented in Figure 45 The barrier height of disTSback is 298 kcal

mol-1 at MRMP2 level shown in Table 10 The activation energy of disTSback is 88 kcal mol-1

higher than that of disTS consistent with the isomerization of benzvalene to benzene being more

kinetically favorable than back to benzvalene The ruptured bond C1-C3 has length of 2563 Å in

disTSback longer than that of 2353 Å in disTS The distance between C1 and C5 is 2550 Å

close to C1-C3 bond length so that the disTSback transition state would lead to benzvalene by

connecting C1 and C5 to close the bicyclobutane moiety The bond length of C5-C6 and C3-C6

are almost equal to 1390 Å suggests π electron delocalization through atoms C5 C6 and C3

103

also visualized by orbital 21 from the MCSCF natural orbitals for disTSback shown in Figure 44

Figure 45 Reactions for the isomerization of benzvalene to benzene and benzvalene


The structures of the conrotatory transition states and intermediates are presented in

Figure 46 The activation barrier of conTS1a is 268 kcal mol-1 62 kcal mol-1 higher than that of

the disrotatory pathway (Table 10) Remarkably an additional intermediate conInta and

transition state conTS1a were located which leads to the transition state conTS2 which rotates the

trans double bond to the cis configuration The geometry of the intermediate conInta has been

optimization at the MCSCFcc-pVTZ level and confirmed a minimum by having all real

harmonic frequencies This is consistent with one of pathways of isomerization of 34-

diazatricyclo[410027]heptane46 conInta is just 41 kcal mol-1 lower than conTS1a at the

MRMP2 level listed in Table 11 For conTS1a the first breaking bond C1-C3 has a length of

2265 Å while the secondary breaking bond C2-C4 has a length of 1565 Å close to 1547 Å in

104

the reactant benzvalene The extra intermediate conInta only lengthened the C1-C3 bond to 2458

Å and maintained the C2-C4 bond as 1566 Å Additionally compared to conTS1a the C5-C6

bond of conInta is lengthened to 1378 Å and the C3-C6 bond is shortened to 1414 Å The nearly

equal bond lengths between C5-C6 and C3-C6 suggests the π bond delocalization runs across

C5-C6-C3 as illustrated in orbital 21 from the MCSCF natural orbitals for conInta in Figure 46

The singlet biradical character of conInta is witnessed by NOON values of 1248 and 0753 for

the σ and σ orbital across C1-C3 Along with the reaction progress the conTS1b lengthens the

secondary breaking bond C2-C4 to 1846 Å The C5-C6 and C3-C6 bonds of conTS1b changed

to 1472 Å and 1350 Å respectively This shortening of C3-C6 implies the double bond transfer

from C5-C6 in conTS1a to C3-C6 in conTS1b This is proof that the double bond in C5-C6

participated in the isomerization of benzvalene to benzene not serving as just a spectator

105

Figure 46 Structures for transition state conTS1a conTS1b and intermediate conInta for the conrotatory pathway


Structurea MCSCFb MRMP2c benzvalene 869 784 conTS1a 1160 1052 conInta 1158 1011 conTS1b 1254 1107 conIntb 993 942 benzene 0 0

a All geometries were optimized at the MCSCF(1010)cc-pVTZ level b The geometries and energies are calculated at the MCSCFcc-pVTZ level c The energies are calculated at the MRMP2cc-pVTZMCSCFcc-pVTZ level

106

432 Benzvalyne

The geometries of benzvalyne and benzyne are shown in Figure 47 For the isomerization

of benzvalyne to benzyne there are also a single disrotatory and single conrotatory pathway

given the point group of C2v for both benzvalyne and benzvalene The saddle points and

intermediates associated with the isomerization of benzvalyne to benzyne were denoted with a

prime symbol to distinguish them from the structures associated with the

isomerization of benzvalene to benzene A schematic diagram for the reaction pathways is shown

in Figure 48

Figure 47 Structures of benzvalyne and isomerization product benzyne

107

Figure 48 Schematic diagram for the isomerization of benzvalyne to benzyne


The structure of the transition state with key geometric feature in the disrotatory pathway

is presented in Figure 49 The activation barrier of disTSprime has been determined to be 229 kcal

mol-1 at the MRMP2 level listed in Table 12 The barrier height for benzvalyne is close to the

206 kcal mol-1 for benzvalene This is consistent with the second π bond in the triple bond in

benzvalyne being orthogonal to the p orbitals on C1 and C3 resulting in the cleavage of the C1-

C3 sigma bond and not in a favorable overlap for delocalization The transition state disTSprime

108

exhibits singlet biradical nature with 1236 Å and 0767 Å NOON values in orbitals 20 and 21

This is obviously different from the transition state disTS with non biradical nature The bond

lengths of the breaking bond pair C1-C3 and C2-C4 are 2506Å and 1628 Å in disTSprime compared

to 2353 Å and 1668 Å in disTS shown in Figure 44 This suggests the isomerization of

benzvalyne via disTSprime is a slightly more asynchronous process The bond length of C5-C6 is

1252 Å in reactant benzvalyne and lengthens to 1274 Å in disTSprime while the C3-C6 bond

shortens from 1494 Å in benzvalyne to 1408 Å in disTSprime This is consistent with electron

delocalization from the in-plane π bonding orbital into the half empty orbital on C3 The p-type

orbital on C3 and delocalized in-plane π orbital across C5-C6-C3 are presented in Figure 49

Figure 49 Transition state structure disTSprime for the disrotatory pathway


Reactiona TSa MCSCFb MRMP2c benzvalyne rarr benzyne disTSprime 263 229 benzvalyne rarr conIntaprime conTS1aprime 258 217 conIntaprimerarr benzyne conTS1bprime 96 14


109


The structures of the transition states and intermediates for the conrotatory pathway are

presented in Figure 50 The activation barrier of conTS1aprime is calculated to be 217 kcal mol-1

only 12 kcal mol-1 lower than that of disrotatory pathway at MRMP2 level listed in Table 12

This means the conrotatory and disrotatory pathways have nearly equally kinetic favorability In

the progress of the isomerization the conrotatory pathway leads to intermediate conIntaprime The

minimum nature of conIntaprime has been verified by geometry optimization and all real harmonic

frequencies conIntaprime has a relative energy of 1222 kcal mol-1 compared to the benzyne reactant

13 kcal mol-1 higher than that of conTS1aprime at the MRMP2 level listed in Table 13 The conTS1aprime

and conIntaprime exhibit similar structural behavior in the reaction The first breaking bond C1-C3

lengthens to 2191 Å in conTS1aprime and 2431 Å in conIntaprime compared to 1558Å in reactant

benzvalyne While the second breaking bond C2-C4 is 1595 Å in conTS1aprime and almost intact in

conIntaprime with bond length of 1602 Å The slight lengthening of C5-C6 and shortening of C3-C6

in conIntaprime compared to conTS1aprime suggests in-plane π bond delocalization between C5-C6-C3 It

is also implied by the singlet biradical nature of intermediate conIntaprime with 1477 and 0524

NOON values in orbitals 20 and 21 The activation barrier for conTS1bprime is only 14 kcal mol-1 at

the MRMP2 level listed in Table 12 The breaking bond pair C1-C3 and C2-C4 lengthen to

2544 Å and 1904 Å in conTS1bprime respectively The neighboring C5-C6 and C3-C6 bonds have

lengths of 1317 Å and 1370 Å in conTS1bprime respectively The closer equality of bond lengths

between C5-C6 and C3-C6 implies in-plane π bond delocalization across C5-C6-C3 It is

consistent with the singlet biradical nature of transition state conTS1bprime witnessed by the NOON

110

values of 1426 and 0584 in orbital 20 and 21 Interestingly the intrinsic reaction coordinates

show conTS1bprime directly connects the intermediate conIntaprime and product benzyne without an

intermediate bearing a trans double bond It is inconsistent with the conrotatory pathway of

benzvalene isomerization and previous studies of similar tricylco-compounds isomerization

46126-129137 This means the 1222 kcal mol-1 relative energy in conIntaprime could be directly released

by only a 14 kcal mol-1 barrier height

Figure 50 Structures for transition state conTS1aprime conTS1bprime and intermediate conIntaprime for the conrotatory pathway

111


Structurea MCSCFb MRMP2c benzvalyne 1061 993 conTS1aprime 1319 1209 conIntaprime 1313 1222 conTS1bprime 1409 1236 benzyne 0 0


44 Conclusion

Both conrotatory and disrotatory pathways for the thermal isomerization of benzvalene

and benzvalyne were calculated at the MCSCFcc-pVTZ level The lowest allowed activation

barrier for the benzvalene isomerization was determined to 258 kcal mol-1 through transition

state disTS with uncustomary singlet configuration character The transition state disTSback with

singlet biradical nature isomerizes back to the benzvalene reactant via a disrotatory pathway The

activation barrier height for disTSback is 88 kcal mol-1 higher than that of disTS It shows the

isomerization of benzvalene to benzene is more kinetically favorable than back to benzvalene

For the conrotatory pathway the activation barrier of conTS1a is 268 kcal mol-1 The extra

intermediate conInta and transition state conTS1a were located on the IRC before the normal

transition state conTS2 bearing the trans double bond in the progress of isomerization During

both disrotatory and conrotatory pathways the double bond between C5-C6 participated in the

isomerization of benzvalene to benzene not serving as a spectator as witnessed by the double

bond transferring from C5-C6 to C3-C6

For the benzvalyne isomerization the activation barrier of disTS prime has been determined to

be 229 kcal mol-1 23 kcal mol-1 lower than that of benzvalene The second π bond in the triple

112

bond contained in benzvalyne is orthogonal to the p orbitals in atom C1 and C3 and is not in a

favorable geometry for delocalization The activation barrier of conTS1aprime is 217 kcal mol-1 12

kcal mol-1 lower compared to the disrotatory pathway The intrinsic reaction coordinates

demonstrate that conTS1bprime leads to the product without an intermediate bearing a trans double

bond This means the 1222 kcal mol-1 stored energy in conIntaprime can be released by only a 14

kcal mol-1 barrier

113

CONCLUSION Dinuclear rhenium catalysts including cis and trans conformers have been synthesized

isolated and characterized Both Re2 complexes were efficient electrocatalyst for CO2 reduction

to CO Catalytic rates were measured by cyclic voltammetry for cis-Re2Cl2 trans-Re2Cl2


respectively The mechanistic studies proved the cis-Re2Cl2 went through bimetallic CO2

activation and conversion The outstanding performance than trans-Re2Cl2 is due to the

limitation of intermolecular deactivation by cofacial arrangement of active sites and the

prevention of intramolecular Re-Re bond formation by the rigid anthracene backbone

The photocatalytic results showed the Re2 catalysts perform significantly better (sim 4X

higher TON) than Re(bpy)(CO)3Cl when the relative concentration in rhenium is held constant

(01 mM dinuclear vs 02 mM mononuclear) The mechanism study suggests a photosensitizer-

based pathway is existed in both Re2 catalysts due to their comparable reactivity despite their

structure The excited-state kinetics and emission spectra reveal that the anthracene backbone

plays a more significant role beyond a simple structural unit

The lowest allowed barrier for the isomerization of DATCE is 361 kcal mol-1 the 122

kcal mol-1 disparity in the disrotatory barriers is due to electron delocalization of the N=N π bond

in DATCE in the transition state and steric effects The isomerization of DATCA shows the

114

energy disparity in the forbidden pathways is explained by the delocalization of the N atom lone

pair into the half-filled orbital on the adjacent carbon atom The isomerization of TATCE was

used to identify π bond electrons showed greater contribution for molecular stabilization than

lone pair electrons

The isomerization of benzvalene to benzene has barriers of 258 kcal mol-1 in disrotatory

channel and 268 kcal mol-1 in conrotatory channel The intrinsic reaction coordinate shows

double bond in C5-C6 participated in the progress of isomerization not server as a spectator The

benzvalyne has barrier of 229 kcal mol-1 in disrotatory channel The slight 23 kcal mol-1 lower

than that of benzvalene due to the second π bond in triple bond in benzvalyne is orthogonal to p

orbitals in atom C1 and C3 and is not in favorable geometry to delocalization The absence of

normally intermediate with trans double bond suggests the up to 1222 kcal mol-1 energy storing

in conIntaprime would be released only by 14 kcal mol-1 barrier

115

BIBLIOGRAPHY

116

(1) Ashford D L Gish M K Vannucci A K Brennaman M K Templeton J L

Papanikolas J M Meyer T J Molecular Chromophore-Catalyst Assemblies for Solar

Fuel Applications Chem Rev 2015 115 (23) 13006ndash13049

(2) Feely R a Sabine C L Lee K Berelson W Kleypas J Fabry V J Millero F J

Impact of Anthropogenic CO2 on the CaCO3 System in the Oceans Science (80- ) 2004

305 (5682) 362ndash366

(3) Houghton J Global Warming Reports Prog Phys 2005 68 (6) 1343ndash1403

(4) Concepcion J J House R L Papanikolas J M Meyer T J Chemical Approaches to

Artificial Photosynthesis Proc Natl Acad Sci U S A 2012 109 (39) 16660ndash15564

(5) Benson E E Kubiak C P Sathrum A J Smieja J M Electrocatalytic and

Homogeneous Approaches to Conversion of CO2 to Liquid Fuels Chem Soc Rev 2009

38 (1) 89ndash99

(6) Yui T Tamaki Y Sekizawa K Ishitani O Photocatalytic Reduction of CO2 From

Molecules to Semiconductors Top Curr Chem 2011 303 151ndash184

(7) Finn C Schnittger S Yellowlees L J Love J B Molecular Approaches to the

Electrochemical Reduction of Carbon Dioxide Chem Commun 2012 48 (10) 1392ndash

1399

(8) Appel A M Bercaw J E Bocarsly A B Dobbek H Dubois D L Dupuis M

Ferry J G Fujita E Hille R Kenis P J A et al Frontiers Opportunities and Challenges in

117

Biochemical and Chemical Catalysis of CO2 Fixation Chem Rev 2013 6621ndash6658

(9) Kang P Chen Z Brookhart M Meyer T J Electrocatalytic Reduction of Carbon

Dioxide Let the Molecules Do the Work Top Catal 2015 30ndash45

(10) Takeda H Cometto C Ishitani O Robert M Electrons Photons Protons and Earth-

Abundant Metal Complexes for Molecular Catalysis of CO2 Reduction ACS Catal 2017

7 (1) 70ndash88

(11) Francke R Schille B Roemelt M Homogeneously Catalyzed Electroreduction of

Carbon Dioxide - Methods Mechanisms and Catalysts Chem Reviw 2018 4631ndash4701


Electrochemical Reduction of Carbon Dioxide Chem Commun 2012 1392ndash1399

(13) Hawecker J Lehn J-M Ziessel R Efficient Photochemical Reduction of CO2 to CO

by Visible Light Irradiation of Systems Containing Re(Bipy)(CO)3X or Ru(Bipy)32+ ndash

Co2+ Combinations as Homogeneous Catalysts J Chem Soc Chem Commun 1983 9

536ndash538

(14) Hawecker J Lehn J-M Ziessel R Electrocatalytic Reduction of Carbon Dioxide

Mediated by Re(Bipy)(CO)3Cl (Bipy = 22rsquo-Bipyridine) J Chem Soc Chem Commun

1984 328ndash330

(15) Hawecker J Lehn J Ziessel R Photochemical and Electrochemical Reduction of

Carbon Dioxide to Carbon Monoxide Mediated by (2 2prime‐Bipyridine)

Tricarbonylchlororhenium (I) and Related Complexes as Homogeneous Catalystsrsquo) Helv

118

Chim Acta 1986 69 1990ndash2012

(16) Johnson F P A George M W Hartl F Turner J J Electrocatalytic Reduction of

CO2 Using the Complexes [Re(Bpy)(CO)3L]n (n = +1 L = P(OEt)3 CH3CN n = 0 L =

Cl- Otf- Bpy = 22rsquo-Bipyridine Otf- = CF3SO3 Organometallics 1996 15 (15) 3374ndash

3387

(17) Breikss A I Abruna H D Electrochemical and Mechanistic Studies of

[Re(CO)3(Dmbpy)Cl] and Their Relation to the Catalytic Reduction of CO2 J

Electroanal Chem interfacial Electrochem 1986 201 (2) 347ndash358

(18) Kurz P Probst B Spingler B Alberto R Ligand Variations in [ReX(Diimine)(CO)3]

Complexes Effects on Photocatalytic CO2 Reduction Eur J Inorg Chem 2006 15

2966ndash2974

(19) Smieja J M Kubiak C P Re(Bipy-TBu)(CO)3Cl-Improved Catalytic Activity for

Reduction of Carbon Dioxide IR-Spectroelectrochemical and Mechanistic Studies Inorg

Chem 2010 49 (20) 9283ndash9289

(20) Machan C W Chabolla S A Kubiak C P Reductive Disproportionation of Carbon

Dioxide by an Alkyl-Functionalized Pyridine Monoimine Re(I) Fac-Tricarbonyl

Electrocatalyst Organometallics 2015 34 (19) 4678ndash4683

(21) Stanton C J Machan C W Vandezande J E Jin T Majetich G F Schaefer H F

Kubiak C P Li G Agarwal J Re(I) NHC Complexes for Electrocatalytic Conversion

of CO2 Inorg Chem 2016 55 (6) 3136ndash3144

(22) Huckaba A J Sharpe E A Delcamp J H Photocatalytic Reduction of CO2 with Re-

119

Pyridyl-NHCs Inorg Chem 2016 55 (2) 682ndash690

(23) Liyanage N P Dulaney H A Huckaba A J Jurss J W Delcamp J H

Electrocatalytic Reduction of CO2 to CO with Re-Pyridyl-NHCs Proton Source Influence

on Rates and Product Selectivities Inorg Chem 2016 55 (12) 6085ndash6094

(24) Ching H Y V Wang X He M Perujo Holland N Guillot R Slim C Griveau S

Bertrand H C Policar C Bedioui F et al Rhenium Complexes Based on 2-Pyridyl-

123-Triazole Ligands A New Class of CO2 Reduction Catalysts Inorg Chem 2017 56

(5) 2966ndash2976

(25) Sung S Kumar D Gil-Sepulcre M Nippe M Electrocatalytic CO2 Reduction by

Imidazolium-Functionalized Molecular Catalysts J Am Chem Soc 2017 139 (40)

13993ndash13996

(26) Nganga J K Samanamu C R Tanski J M Pacheco C Saucedo C Batista V S

Grice K A Ertem M Z Angeles-Boza A M Electrochemical Reduction of CO2

Catalyzed by Re(Pyridine-Oxazoline)(CO)3Cl Complexes Inorg Chem 2017 56 (6)

3214ndash3226

(27) Nakada A Ishitani O Selective Electrocatalysis of a Water-Soluble Rhenium(I)

Complex for CO2 Reduction Using Water As an Electron Donor ACS Catal 2018 8 (1)

354ndash363

(28) Ha E G Chang J A Byun S M Pac C Jang D M Park J Kang S O High-

Turnover Visible-Light Photoreduction of CO2 by a Re(i) Complex Stabilized on Dye-

Sensitized TiO2 Chem Commun 2014 50 (34) 4462ndash4464

120

(29) Won D Il Lee J S Ji J M Jung W J Son H J Pac C Kang S O Highly

Robust Hybrid Photocatalyst for Carbon Dioxide Reduction Tuning and Optimization of

Catalytic Activities of DyeTiO2Re(I) Organic-Inorganic Ternary Systems J Am Chem

Soc 2015 137 (42) 13679ndash13690

(30) Windle C D Pastor E Reynal A Witwood A C Vaynzof Y Durrant J R

Perutz R N Reisner E Improving the Photocatalytic Reduction of CO2 to CO through

Immobilisation of a Molecular Re Catalyst on TiO2 Chem - A Eur Journals 2015 21

3746ndash3754

(31) Sahara G Abe R Higashi M Morikawa T Maeda K Ueda Y Ishitani O

Photoelectrochemical CO2 Reduction Using a Ru(Ii)-Re(i) Multinuclear Metal Complex

on a p-Type Semiconducting NiO Electrode Chem Commun 2015 51 (53) 10722ndash

10725

(32) Sahara G Kumagai H Maeda K Kaeffer N Artero V Higashi M Abe R

Ishitani O Photoelectrochemical Reduction of CO2 Coupled to Water Oxidation Using a

Photocathode with a Ru(II)-Re(I) Complex Photocatalyst and a CoOxTaON Photoanode

J Am Chem Soc 2016 138 (42) 14152ndash14158

(33) Schreier M Luo J Gao P Moehl T Mayer M T Graumltzel M Covalent

Immobilization of a Molecular Catalyst on Cu2O Photocathodes for CO2 Reduction J

Am Chem Soc 2016 138 (6) 1938ndash1946

(34) Kucharski T J Tian Y Akbulatov S Boulatov R Chemical Solutions for the Closed-

Cycle Storage of Solar Energy Energy Environ Sci 2011 4 (11) 4449

121

(35) Kuisma M J Lundin A M Moth-Poulsen K Hyldgaard P Erhart P Comparative

Ab-Initio Study of Substituted Norbornadiene-Quadricyclane Compounds for Solar

Thermal Storage J Phys Chem C 2016 120 (7) 3635ndash3645

(36) Blanchard E P Cairncross A Bicyclo[110]Butane Chemistry I The Synthesis and

Reactions of 3-Methylbicyclo[110]Butanecarbonitriles J Am Chem Soc 1966 88 (3)

487ndash495

(37) Cairncross A Blanchard E P Bicyclo[110]Butane Chemistry II Cycloaddition

Reactions of 3-Methylbicyclo[110]Butanecarbonitriles The Formation of

Bicyclo[211]Hexanes J Am Chem Soc 1966 88 (3) 496ndash504

(38) Dewar M J S Kirschner S MINDO3 Study of Thermolysis of Bicyclobutane

Allowed and Stereoselective Reaction That Is Not Concerted J Am Chem Soc 1975 97

(10) 2931ndash2932

(39) Shevlin P B McKee M L A Theoretical Investigation of the Thermal Ring Opening of

Bicyclobutane to Butadiene Evidence for a Nonsynchronous Processdagger J Am Chem Soc

1988 110 (6) 1666ndash1671

(40) Nguyen K A Gordon M S Isomerization Of Bicyclo[110]Butane to Butadiene J

Am Chem Soc 1995 117 (13) 3835ndash3847

(41) Wang H Law C K Thermochemistry of Benzvalene Dihydrobenzvalene and Cubane

A High-Level Computational Study J Phys Chem B 1997 101 (17) 3400ndash3403

(42) Davis S R Veals J D Scardino D J Zhao Z Isomerization Barriers and Strain

Energies of Selected Dihydropyridines and Pyrans with Trans Double Bonds J Phys

122

Chem A 2009 113 (30) 8724ndash8730

(43) Cuppoletti A Dinnocenzo J P Goodman J L Gould I R Bond-Coupled Electron

Transfer Reactions Photoisomerization of Norbornadiene to Quadricyclane J Phys

Chem A 1999 103 (51) 11253ndash11256

(44) Yang W Roy S S Pitts W C Nelson R L Fronczek F R Jurss J W

Electrocatalytic CO2 Reduction with Cis and Trans Conformers of a Rigid Dinuclear

Rhenium Complex  Comparing the Monometallic and Cooperative Bimetallic Pathways

Inorg Chem 2018 57 9564ndash9575

(45) Liyanage N P Yang W Guertin S L Sinha Roy S Carpenter C A Adams R E

Schmehl R Delcamp J Jurss J W Photochemical CO2 Reduction with Mononuclear

and Dinuclear Rhenium Catalysts Bearing a Pendant Anthracene Chromophore Chem

Commun 2018 2 993ndash996

(46) Yang W Poland K N Davis S R Isomerization Barriers and Resonance Stabilization

for the Conrotatory and Disrotatory Isomerizations of Nitrogen Containing Tricyclo

Moieties Phys Chem Chem Phys 2018 20 (41) 26608ndash26620

(47) Sullivan B P Bolinger C M Conrad D Vining W J Meyer T J One-and Two-

Electron Pathways in the Electrocatalytic Reduction of CO2 by Fac-Re( Bpy)(CO)3Cl

(Bpy = 22rsquo-Bipyridine) J Chem Soc Chem Commun 1985 1414ndash1416

(48) Roffia S Amatore C Paradisi C Marcaccio M Bignozzi C A Paolucci F

Dynamics of the Electrochemical Behavior of Diimine Tricarbonyl Rhenium(I)

Complexes in Strictly Aprotic Media J Phys Chem B 1998 102 (24) 4759ndash4769

123

(49) Hayashi Y Kita S Brunschwig B S Fujita E Involvement of a Binuclear Species

with the Re-C(O)O-Re Moiety in CO2 Reduction Catalyzed by Tricarbonyl Rhenium(I)

Complexes with Diimine Ligands Strikingly Slow Formation of the Re-Re and Re-

C(O)O-Re Species from Re(Dmb)(CO)3S (Dmb=44prime-Dimethyl-22prime-B J Am Chem Soc

2003 125 (39) 11976ndash11987

(50) Fujita E Muckerman J T Why Is Re-Re Bond FormationCleavage in [Re(Bpy)(CO)3]2

Different from That in [Re(CO)5]2 Experimental and Theoretical Studies on the Dimers

and Fragments Inorg Chem 2004 43 (24) 7636ndash7647

(51) Agarwal J Fujita E Schaefer H F Muckerman J T Mechanisms for CO Production

from CO2 Using Reduced Rhenium Tricarbonyl Catalysts J Am Chem Soc 2012 134

5180ndash5186

(52) Benson E E Kubiak C P Structural Investigations into the Deactivation Pathway of

the CO2 Reduction Electrocatalyst Re(Bpy)(CO)3Cl Chem Commun 2012 48 (59)

7374ndash7376

(53) Church T L Zhou C Liang W Zheng S DrsquoAlessandro D M Haynes B S Site

Isolation Leads to Stable Photocatalytic Reduction of CO2 over a Rhenium-Based

Catalyst Chem - A Eur J 2015 21 (51) 18576ndash18579

(54) Machan C W Sampson M D Chabolla S A Dang T Kubiak C P Developing a

Mechanistic Understanding of Molecular Electrocatalysts for CO2 Reduction Using

Infrared Spectroelectrochemistry Organometallics 2014 33 (18) 4550ndash4559

(55) Kou Y Nabetani Y Masui D Shimada T Takagi S Tachibana H Inoue H

124

Direct Detection of Key Reaction Intermediates in Photochemical CO2 Reduction

Sensitized by a Rhenium Bipyridine Complex J Am Chem Soc 2014 136 (16) 6021ndash

6030

(56) Bruckmeier C Lehenmeier M W Reithmeier R Rieger B Herranz J Kavakli C

Binuclear Rhenium(i) Complexes for the Photocatalytic Reduction of CO2 Dalt Trans

2012 41 (16) 5026ndash5037

(57) Tamaki Y Imori D Morimoto T Koike K Ishitani O High Catalytic Abilities of

Binuclear Rhenium(i) Complexes in the Photochemical Reduction of CO2 with a

Ruthenium(II) Photosensitiser Dalt Trans 2016 45 (37) 14668ndash14677

(58) Machan C W Chabolla S A Yin J Gilson M K Tezcan F A Kubiak C P

Supramolecular Assembly Promotes the Electrocatalytic Reduction of Carbon Dioxide by

Re(I) Bipyridine Catalysts at a Lower Overpotential J Am Chem Soc 2014 136 (41)

14598ndash14607

(59) Machan C W Yin J Chabolla S A Gilson M K Kubiak C P Improving the

Efficiency and Activity of Electrocatalysts for the Reduction of CO2 through

Supramolecular Assembly with Amino Acid-Modified Ligands J Am Chem Soc 2016

138 (26) 8184ndash8193

(60) Shakeri J Hadadzadeh H Tavakol H Photocatalytic Reduction of CO2 to CO by a

Dinuclear Carbonyl Polypyridyl Rhenium(I) Complex Polyhedron 2014 78 112ndash122

(61) Rezaei B Ensafi A A Hadadzadeh H Shakeri J Mokhtarianpour M

Electrocatalytic Reduction of CO2 Using the Dinuclear Rhenium(I) Complex

125

[ReCl(CO)3(μ-TptzH)Re(CO)3] Polyhedron 2015 101 160ndash164

(62) Wilting A Stolper T Mata R A Siewert I Dinuclear Rhenium Complex with a

Proton Responsive Ligand as a Redox Catalyst for the Electrochemical CO2 Reduction

Inorg Chem 2017 56 (7) 4176ndash4185

(63) Wilting A Siewert I A Dinculear Rhenium Complex with a Proton Responsive Ligand

in the Electrochemical-Driven CO2-Reduction Catalysis ChemistrySelect 2018 3 (17)

4593ndash4597

(64) APEX2 v 2009 Bruker Analytical X-Ray Systems Inc Madison WI 2009

(65) Sheldrick G M SADABS Version 203 Bruker Analytical X-Ray Sys-Tems Inc

Madison WI 2000

(66) Sheldrick G M Phase Annealing in SHELX‐90 Direct Methods for Larger Structures

Acta Crystallogr Sect A 1990 46 (6) 467ndash473

(67) Sheldrick G M A Short History of SHELX Acta Crystallogr Sect A Found

Crystallogr 2008 64 (1) 112ndash122

(68) Sheldrick G M SHELXL-20147 Program for Crystal Structure Determina-Tion

University of Gottingen Gottingen Germany 2014

(69) Spek A L PLATON - A Multipurpose Crystallographic Tool Utrecht Uni-Versity

Utrecht The Netherlands 2007

(70) Spek A L PLATON SQUEEZE A Tool for the Calculation of the Disordered Solvent

Contribution to the Calculated Structure Factors Acta Crystallogr Sect C Struct Chem

2015 71 9ndash18

126

(71) Frisch M J et Al Gaussian 09 Revision D01 Gaussian Inc Wallingford CT 2009

(72) Lin Y S Li G De Mao S P Chai J Da Long-Range Corrected Hybrid Density

Functionals with Improved Dispersion Corrections J Chem Theory Comput 2013 9 (1)

263ndash272

(73) Minenkov Y Singstad Aring Occhipinti G Jensen V R The Accuracy of DFT-

Optimized Geometries of Functional Transition Metal Compounds A Validation Study of

Catalysts for Olefin Metathesis and Other Reactions in the Homogeneous Phase Dalt

Trans 2012 41 (18) 5526ndash5541

(74) Caspar J V Meyer T J Application of the Energy Gap Law to Nonradiative Excited-

State Decay J Phys Chem 1983 87 (6) 952ndash957

(75) Boumlttger M Wiegmann B Schaumburg S Jones P G Kowalsky W Johannes H-

H Synthesis of New Pyrrole-Pyridine-Based Ligands Using an in Situ Suzuki Coupling

Method Beilstein J Org Chem 2012 8 1037ndash1047

(76) Wada T Muckerman J T Fujita E Tanaka K Substituents Dependent Capability of

Bis(Ruthenium-Dioxolene-Terpyridine) Complexes toward Water Oxidation Dalt Trans

2011 40 (10) 2225ndash2233

(77) Richard P Collman J P Guilard R Brandes S Tabard A Lopez M A Lecomte

C Hutchison J E Synthesis and Characterization of Novel Cobalt Aluminum Cofacial

Porphyrins First Crystal and Molecular Structure of a Heterobimetallic Biphenylene

Pillared Cofacial Diporphyrin J Am Chem Soc 1992 114 (25) 9877ndash9889

(78) Fraser M G Clark C A Horvath R Lind S J Blackman A G Sun X Z George

127

M W Gordon K C Complete Family of Mono- Bi- and Trinuclear ReI(CO)3Cl

Complexes of the Bridging Polypyridyl Ligand 23891415- Hexamethyl-

5611121718-Hexaazatrinapthalene SynAnti Isomer Separation Characterization and

Photophysics Inorg Chem 2011 50 (13) 6093ndash6106

(79) Kolthoff L Polurogruphy (interscience N Y A Cathode Ray Polarography Part II-

The Current- Voltage Curves Trans Favaduy SOC 1948 327ndash328

(80) Bard A J Faulkner L R Electrochemical Methods Fundamentals and Applications

2nd Editio John Wiley and Sons New York 2001

(81) Richardson D E Taube H Mixed-Valence Molecules Electronic Delocalization and

Stabilization Coord Chem Rev 1984 60 107ndash129

(82) Manes T A Rose M J Redox Properties of a Bis-Pyridine Rhenium Carbonyl Derived

from an Anthracene Scaffold Inorg Chem Commun 2015 61 221ndash224

(83) Saveacuteant J M Vianello E Potential-Sweep Chronoamperometry Theory of Kinetic

Currents in the Case of a First Order Chemical Reaction Preceding the Electron-Transfer

Process Electrochim Acta 1963 8 (12) 905ndash923

(84) Nicholson R S Shain I Theory of Stationary Electrode Polarography Single Scan and

Cyclic Methods Applied to Reversible Irreversible and Kinetic Systems Anal Chem

1964 36 (4) 706ndash723

(85) Rountree E S McCarthy B D Eisenhart T T Dempsey J L Evaluation of

Homogeneous Electrocatalysts by Cyclic Voltammetry Inorg Chem 2014 53 (19)

9983ndash10002

128

(86) Huang D Makhlynets O V Tan L L Lee S C Rybak-Akimova E V Holm R H

Kinetics and Mechanistic Analysis of an Extremely Rapid Carbon Dioxide Fixation

Reaction Proc Natl Acad Sci 2011 108 (4) 1222ndash1227

(87) Steffey B D Curtis C J Dubois D L Electrochemical Reduction of CO2 Catalyzed

by a Dinuclear Palladium Complex Containing a Bridging Hexaphosphine Ligand

Evidence for Cooperativity 1995 Vol 14

(88) Raebiger J W Turner J W Noll B C Curtis C J Miedaner A Cox B DuBois

D L Electrochemical Reduction of CO2 to CO Catalyzed by a Bimetallic Palladium

Complex Organometallics 2006 25 (14) 3345ndash3351

(89) Yang L Abu-Omar M M Wegenhart B Liu S Ison E A Senocak A Kenttaumlmaa

H I Smeltz J L Yi J Mechanism of MTO-Catalyzed Deoxydehydration of Diols to

Alkenes Using Sacrificial Alcohols Organometallics 2013 32 (11) 3210ndash3219

(90) Guisaacuten-Ceinos M Buntildeuel E Soler-Yanes R Arribas-Aacutelvarez I Caacuterdenas D J NiI

Catalyzes the Regioselective Cross-Coupling of Alkylzinc Halides and Propargyl

Bromides to Allenes Chem - A Eur J 2017 23 (7) 1584ndash1590

(91) Costentin C Drouet S Robert M Saveacuteant J M Turnover Numbers Turnover

Frequencies and Overpotential in Molecular Catalysis of Electrochemical Reactions

Cyclic Voltammetry and Preparative-Scale Electrolysis J Am Chem Soc 2012 134

(27) 11235ndash11242

(92) Costentin C Robert M Saveacuteant J-M Catalysis of the Electrochemical Reduction of

Carbon Dioxide dagger Chem Soc Rev 2013 42 2423

129

(93) Wiedner E S Bullock R M Electrochemical Detection of Transient Cobalt Hydride

Intermediates of Electrocatalytic Hydrogen Production J Am Chem Soc 2016 138 (26)

8309ndash8318

(94) Wong K Y Chung W H Lau C P The Effect of Weak Broumlnsted Acids on the

Electrocatalytic Reduction of Carbon Dioxide by a Rhenium Tricarbonyl Bipyridyl

Complex J Electroanal Chem 1998 453(1) 161-170

(95) Seu C S Grice K A Mayer J M Smieja J M Kubiak C P Miller A J M

Benson E E Kumar B Kinetic and Structural Studies Origins of Selectivity and

Interfacial Charge Transfer in the Artificial Photosynthesis of CO Proc Natl Acad Sci

2012 109 (39) 15646ndash15650

(96) Maran F Celadon D Severin M G Vianello E Electrochemical Determination of

the PKa of Weak Acids in NN-Dimethylformamide J Am Chem Soc 1991 113 9320ndash

9329

(97) Olmstead B Steiner J H  Acidities of Water and Simple Alcohols in Dimethyl

Sulfoxide Solution J Org Chem 1980 45 (16) 299ndash329

(98) Taft R W Bordwell F G Structural and Solvent Effects Evaluated from Acidities

Measured in Dimethyl Sulfoxide and in the Gas Phase Acc Chem Res 1988 21 (14)

463ndash469

(99) Bordwell F G Mccallum R J Olmstead W N Acidities and Hydrogen Bonding of

Phenols in Dimethyl Sulfoxide J Org Chem 1984 49 (38) 1424ndash1427

(100) Pegis M L Roberts J A S Wasylenko D J Mader E A Appel A M Mayer J

130

M Standard Reduction Potentials for Oxygen and Carbon Dioxide Couples in Acetonitrile

and NN-Dimethylformamide Inorg Chem 2015 54 (24) 11883ndash11888

(101) Appel A M Helm M L Determining the Overpotential for a Molecular

Eelectrocatalyst ACS Catal 2014 4 (2) 630ndash633

(102) Lee G R Maher J M Cooper N J Reductive Disproportionation of Carbon Dioxide

by Dianionic Carbonylmetalates of the Transition Metals J Am Chem Soc 1987 109

(10) 2956ndash2962

(103) Ratliff K S Lentz R E Kubiak C P Carbon Dioxide Chemistry of the Trinuclear

Complex [Ni3(μ3-CNMe)(μ3-I)(Dppm)3][PF6] Electrocatalytic Reduction of Carbon

Dioxide Organometallics 1992 11 (6) 1986ndash1988

(104) Fei H Sampson M D Lee Y Kubiak C P Cohen S M Photocatalytic CO2

Reduction to Formate Using a Mn(I) Molecular Catalyst in a Robust MetalminusOrganic

Framework Inorg Chem 2015 54 6821ndash6828

(105) Story N Bolinger C M Conrad D Gilbert J A Meyer T J Sullivan B P

Electrocatalytic Reduction of CO2 Based on Polypyridyl Complexes of Rhodium and

Ruthenium J Chem Soc Chem Commun 1985 12 796ndash797

(106) Sampson M D Froehlich J D Smieja J M Benson E E Sharp I D Kubiak C P

Direct Observation of the Reduction of Carbon Dioxide by Rhenium Bipyridine Catalysts

Energy Environ Sci 2013 6 (12) 3748ndash3755

(107) Christensen P A Hamnett A Muir A V G Freeman N A CO2 Reduction at

Platinum Gold and Glassy Carbon Electrodes in Acetonitrile An in-Situ FTIR Study J

131

Electroanal Chem 1990 288 197ndash215

(108) Cheng S C Blaine C A Hill M G Mann K R Electrochemical and IR

Spectroelectrochemical Studies of the Electrocatalytic Reduction of Carbon Dioxide by [Ir

2 (Dimen) 4 ] 2+ (Dimen = 18-Diisocyanomenthane) Inorg Chem 1996 35 (26) 7704ndash

7708

(109) Takeda H Koike K Inoue H Ishitani O Development of an Efficient Photocatalytic

System for CO2 Reduction Using Rhenium(I) Complexes Based on Mechanistic Studies




2012 41 (16) 5026ndash5037

(111) Thoi V S Kornienko N Margarit C G Yang P Chang C J Visible-Light

Photoredox Catalysis Selective Reduction of Carbon Dioxide to Carbon Monoxide by a

Nickel N-Heterocyclic Carbene-Isoquinoline Complex J Am Chem Soc 2013 135 (38)

14413ndash14424

(112) Guo Z Yu F Yang Y Leung C-F Ng S-M Ko C-C Cometto C Lau T-C

Robert M Photocatalytic Conversion of CO2 to CO by a Copper(II) Quaterpyridine

Complex ChemSusChem 2017 10 (20) 4009ndash4013

(113) Simon J A Curry S L Schmehl R H Schatz T R Piotrowiak P Jin X

Thummel R P Intramolecular Electronic Energy Transfer in Ruthenium(II) Diimine

DonorPyrene Acceptor Complexes Linked by a Single C-C Bond J Am Chem Soc

132

1997 119 (45) 11012ndash11022

(114) Tyson D S Henbest K B Bialecki J Castellano F N Excited State Processes in

Ruthenium(II)Pyrenyl Complexes Displaying Extended Lifetimes J Phys Chem A

2001 105 (35) 8154ndash8161

(115) Del Guerzo A Leroy S Fages F Schmehl R H Photophysics of Re(I) and Ru(II)

Diimine Complexes Covalently Linked to Pyrene Contributions from Intra-Ligand

Charge Transfer States Inorg Chem 2002 41 (2) 359ndash366

(116) Harriman A Hissler M Khatyr A Ziessel R A Ruthenium(II) Tris(22rsquo-Bipyridine)

Derivative Possessing a Triplet Lifetime of 42 Μs Chem Commun 1999 0 (8) 735ndash736

(117) Balazs G C Schmehl R H Photophysical Behavior and Intramolecular Energy

Transfer in Os(II) Diimine Complexes Covalently Linked to Anthracenedagger Photochem

Photobiol Sci 2005 4 89ndash94

(118) Genoni A Chirdon D N Boniolo M Sartorel A Bernhard S Bonchio M Tuning

Iridium Photocatalysts and Light Irradiation for Enhanced CO2 Reduction ACS Catal

2017 7 (1) 154ndash160

(119) Naab B D Guo S Olthof S Evans E G B Wei P Millhauser G L Kahn A

Barlow S Marder S R Bao Z Mechanistic Study on the Solution-Phase n-Doping of

13-Dimethyl-2-Aryl-23-Dihydro-1 H -Benzoimidazole Derivatives J Am Chem Soc

2013 135 (40) 15018ndash15025

(120) Cope J D Liyanage N P Kelley P J Denny J A Valente E J Webster C E

Delcamp J H Hollis T K Li R Electrocatalytic Reduction of CO2 with CCC-NHC

133

Pincer Nickel Complexes dagger Chem Commun 2017 53 9442

(121) Bonin J Robert M Routier M Selective and Efficient Photocatalytic CO2 Reduction to

CO Using Visible Light and an Iron-Based Homogeneous Catalyst J Am Chem Soc

2014 136 (48) 16768ndash16771

(122) Rodrigues R R Boudreaux C M Papish E T Delcamp J H Photocatalytic

Reduction of CO2 to CO and Formate Do Reaction Conditions or Ruthenium Catalysts

Control Product Selectivity ACS Appl Energy Mater 2018 2 (1) 37ndash46

(123) S L Murov I Carmichael and G L Hug ldquoHandbook of Photochemistryrdquo Ch 1 Marcel

Dekker New York 1993 p 7

(124) Walther M E Wenger O S Energy Transfer from Rhenium(i) Complexes to

Covalently Attached Anthracenes and Phenanthrenes J Chem Soc Dalt Trans 2008

44 6311ndash6318

(125) Worl L A Duesing R Chen P Ciana L Della Meyer T J Photophysical Properties

of Polypyridyl Carbonyl Complexes of Rhenium(I) J Chem Soc Dalt Trans 1991 0

849ndash858

(126) Zhao Z Davis S R Cleland W E Ab Initio Study of the Pathways and Barriers of

Tricyclo[410027 ]Heptene Isomerization J Phys Chem A 2010 114 (43) 11798ndash

11806

(127) Veals J D Davis S R Isomerization Barriers for the Conrotatory and Disrotatory

Isomerizations of 3-Aza-Dihydrobenzvalene to 12-Dihydropyridine and 34-Diaza-

Dihydrobenzvalene to 12-Dihydropyridazine Comput Theor Chem 2013 1020 127ndash

134

135

(128) Veals J D Davis S R Isomerization Barriers for the Disrotatory and Conrotatory

Isomerizations of 3-Aza-Benzvalene and 34-Diaza-Benzvalene to Pyridine and

Pyridazine Phys Chem Chem Phys 2013 15 (32) 13593ndash13600

(129) Qin C Davis S R Thermal Isomerization of Tricyclo[410027]Heptane and

Bicyclo[320]Hept-6-Ene through the (EZ)-13-Cycloheptadiene Intermediate J Org

Chem 2003 68 (23) 9081ndash9087

(130) Schmidt M W Baldridge K K Boatz J A Elbert S T SGordon M Jensen J H

Koseki S Matsunaga N Nguyen K A Su S J et al General Atomic and Molecular

Electronic Structure System J Comput Chem 1993 14 1347ndash1363

(131) Boys S F Quantum Science of Atoms Molecules and Solids Ed A P Ed NY 1966

(132) Woon D E Thom H Dunning J Gaussian Basis Sets for Use in Correlated Molecular

Calculations III The Atoms Aluminum through Argon J Chem Phys 1993 98 (2)

1358ndash1371

(133) Gonzalez C Bernhard Schlegel H An Improved Algorithm for Reaction Path

Following J Chem Phys 1989 90 (4) 2154ndash2161

(134) Hirao K Multireference Moslashller-Plesset Method Chem Phys Lett 1992 190 (3ndash4) 374ndash

380

(135) Hirao K Multireference Moslashller-Plesset Perturbation Theory for High-Spin Open-Shell

Systems Chem Phys Lett 1992 196 (5) 397ndash403

(136) Frisch M J Trucks G W Schlegel H B Scuseria G E Robb M A Cheeseman J

135

R Scalmani G Barone V Petersson G A Nakatsuji H et al Gaussian16 revision

B01 2016

(137) Veals J D Poland K N Earwood W P Yeager S M Copeland K L Davis S R

MRMP2 CCSD(T) and DFT Calculations of the Isomerization Barriers for the

Disrotatory and Conrotatory Isomerizations of 3-Aza-3-Ium-Dihydrobenzvalene 34-

Diaza-3-Ium-Dihydrobenzvalene and 34-Diaza-Diium-Dihydrobenzvalene J Phys

Chem A 2017 121 (46) 8899ndash8911

(138) Ritscher J S Kaplan L Wilzbach K E Benzvalene the Tricyclic Valence Isomer of

Benzene J Am Chem Soc 1967 89 (4) 1031ndash1032

(139) Dewar M J S Kirschner S The Conversion of Benzvalene to Benzene J Am Chem

Soc 1975 97 (10) 2932ndash2933

(140) Renner C A Katz J Haven N Kinetics and Thermochemistry of the Rearrangement of

Benzvalene to Benzene An Energy Sufficient but Non-Chemiluminescent Reaction

Tetrahedron Lett 1976 2 (46) 4133ndash4136

(141) Merz K M Lawrence T The C6H6 PES Automerization of Benzene J Chem Soc

1993 412 412ndash414

(142) Bettinger H F Schreiner P R Schaefer H F Schleyer P v R Rearrangements on

the C6H6 Potential Energy Surface and the Topomerization of Benzene J Am Chem

Soc 1998 120 (23) 5741ndash5750

(143) Schulman J M Disch R L Ab Initio Heats of Formation of Medium-Sized

Hydrocarbons The Heat of Formation of Dodecahedrane J Am Chem Soc 1985 106

136

(5) 1202ndash1204

(144) Wang H Law C K Thermochemistry of Benzvalene Dihydrobenzvalene and

Cubane  A High-Level Computational Study Society 1997 5647 (96) 3400ndash3403

(145) Kislov V V Nguyen T L Mebel A M Lin S H Smith S C Photodissociation of

Benzene under Collision-Free Conditions An Ab InitioRice-Ramsperger-Kassel-Marcus

Study J Chem Phys 2004 120 (15) 7008ndash7017

(146) Wang H Laskin A Moriarty N W Frenklach M On Unimolecular Decomposition

of Phenyl Radical Proc Combust Inst 2000 28 1545ndash1555

(147) Dubrovskiy A V Markina N A Larock R C Use of Benzynes for the Synthesis of

Heterocycles Org Biomol Chem 2013 11 191

(148) Matsugi A Miyoshi A Reactions of O-Benzyne with Propargyl and Benzyl Radicals

Potential Sources of Polycyclic Aromatic Hydrocarbons in Combustion Phys Chem

Chem Phys 2012 14 (27) 9722ndash9728

(149) Comandini A Brezinsky K Radicalπ-Bond Addition between o -Benzyne and Cyclic C

5 Hydrocarbons J Phys Chem A 2012 116 (4) 1183ndash1190

(150) Bauschlicher C W Ricca A On the Calculation of the Vibrational Frequencies of

C6H4 Chem Phys Lett 2013 566 1ndash3

(151) Jiao H Schleyer P V R Beno B R Houk K N Warmuth R Theoretical Studies of

the Structure Aromaticity and Magnetic Properties of o-Benzyne Communications

1997 2 2761ndash2764

(152) Moskaleva L V Madden L K Lin M C Kassel R Egrave Marcus Egrave Unimolecular

137

Isomerization Decomposition of Ortho -Benzyne  Ab Initio MO Statistical Theory

Study 1999 3967ndash3972

(153) Ghigo G Maranzana A Tonachini G o-Benzyne Fragmentation and Isomerization

Pathways A CASPT2 Study Phys Chem Chem Phys 2014 16 (43) 23944ndash23951

(154) Blake M E Bartlett K L Jones M A m-Benzyne to o-Benzyne Conversion through a

12-Shift of a Phenyl Group Tetrahedron 2003 125 (6) 6485ndash6490

(155) Halton B Cooney M J Jones C S Boese R Blaumlser D C6H4 Valence Bond Isomers

A Reactive Bicyclopropenylidene Org Lett 2004 6 (22) 4017ndash4020

138

LIST OF APPENDICES

139

APPENDIX A

140

Figure A1 Calculated energy barrier to rotational interconversion between the asymmetric trans- Re2Cl2 and symmetric cis conformers cis-Re2Cl2 and cis 2 (as identified in Figure A2) Fully optimized with wB97X-D functional and LanL2TZ(f) (Re atoms) 6-311+G (COs and coordinating Ns) and 6-311G (all other atoms) basis sets

141

NN

NN

Re ReClOC

COOCOC CO

Cl CO

cis-Re2Cl2(CS

symmetric Cl-in)

trans-Re2Cl2(asymmetric C1

1Cl-in 1Cl-out)

N

N

N

N

Re

Re

OC

OC

OC

OCCl

Cl

OC

CO

NN

NN

Re ReOCCl

COOCOC CO

CO Cl

cis 2

(CS symmetric Cl-out)

NN

NN

Re ReClCl

COOCOC CO

CO CO

cis 3

(asymmetric C1)

NN

NN

Re ReOCOC

COOCOC CO

Cl Cl

trans 2

(C2 symmetric Cl-in)

N

N

N

N

Re

Re

OC

OC

OC

OCCl

CO

Cl

CO

N

N

N

N

Re

Re

OC

OC

OC

OCOC

Cl

OC

Cl

N

N

N

N

Re

Re

OC

OC

OC

OCOC

CO

Cl

Cl

cis 4

(asymmetric C1)

enantiomers

same

trans 3

(C2 symmetric Cl-out)

1 2

4

6

7

5

3

142

Figure A2 The seven possible isomers maintaining the fac-tricarbonyl arrangement that could be formed upon metalation

Figure A3 1H NMR spectrum (500 MHz DMSO-d6) showing the aromatic region of the crude reaction mixture following metalation of ligand 1 with two equivalents of Re(CO)5Cl

Figure A4 Experimental FTIR spectra of A) cis-Re2Cl2 and B) trans-Re2Cl2 in DMF solution showing the CO vibrational modes

714

717

718

724

725

727

733

743

744

748

750

752

753

755

760

762

764

765

769

771

773

774

774

776

783

788

790

791

800

802

803

834

835

837

839

840

842

856

858

860

862

868

869

872

874

876

878

888

898

899

900

902

903

904

7273747576777879808182838485868788899091f1 (ppm)

143

Figure A5 Calculated infrared spectra showing the CO vibrational modes of A) cis 2 B) cis-Re2Cl2 and C) trans-Re2Cl2 as specified in Figure S1 in DMF using the COSMO solvation mode

Figure A6 A) Cyclic voltammograms at different scan rates with 2 mM Re(bpy)(CO)3Cl in DMF01 M Bu4NPF6 solutions under Ar glassy carbon disc B) Scan rate dependence reductive peak current vs the square root of scan rate (ν12) for each reduction The given line equation corresponds to the linear fit shown in black (first reduction) which was used to calculate the diffusion coefficient D = 540 x 10-6 cm2 s-1

144

Figure A7 A) Cyclic voltammograms at different scan rates with 2 mM anthryl-Re in DMF01 M Bu4NPF6 solutions under Ar glassy carbon disc B) Scan rate dependence reductive peak current vs the square root of scan rate (ν12) for each reduction The given line equation corresponds to the linear fit shown in black (first reduction) which was used to calculate the diffusion coefficient D = 540 x 10-6 cm2 s-1

Figure A8 A) Cyclic voltammograms at different scan rates with 1 mM cis-Re2Cl2 in DMF01 M Bu4NPF6 solutions under Ar glassy carbon disc B) Scan rate dependence reductive peak current vs the square root of scan rate (ν12) for each reduction The given line equation corresponds to the linear fit shown in black for the second of the two initial overlapping 1e- reductions

145


Reliable diffusion coefficients could not be calculated from the scan rate dependent CVs

of the dinuclear complexes due to the initial overlapping reductions From the indicated slopes

diffusion coefficients of 116 x 10-5 cm2 s-1 (cis-Re2Cl2) and 113 x 10-5 cm2 s-1 (trans-Re2Cl2) are

obtained using the Randles-Sevcik equation (eq 1) where n the number of electrons transferred

in the redox event was taken to be 1 However the current response is complicated by the

intersecting waves

119894119894119890119890 = 04463119899119899119865119865119865119865119862119862 119899119899119865119865νD119877119877119877119877

12

Equation 1

which simplifies to 119894119894119890119890 = (269 times 105)1198991198993 2frasl 1198651198651198631198631 2frasl 119862119862ν1 2frasl (at 298 K)

In eq 1 ip is the current (in A) F is Faradayrsquos constant (96485 Cmol) A is the surface

area of the working electrode (00707 cm2 for a 3 mm diameter glassy carbon disc) C is the

concentration of the electroactive species (in molcm3 ie a 1 mM concentration is 1 x 10-6

146

molcm3) ν is the scan rate (in Vs) D is the diffusion coefficient (in cm2s) R is the ideal gas

constant (8314 J(molbullK) and T is the temperature (in K) The following conversion is also

useful V = JC in working out the units

Figure A10 Cyclic voltammetry of cis-Re2Cl2 free ligand 1 (18-di([22-bipyridin]-6-yl) anthracene) and Re(bpy)(CO)3Cl in DMF01 M Bu4NPF6 solutions glassy carbon disc ν = 100 mVs

-15 -18 -21 -24 -27-40

-20

0

20

40

60

80

Cur

rent

micro

A

Potential V vs Fc+0

cis-Re2Cl2 Re(bpy)(CO)3Cl free ligand 1

147

Figure A11 Cyclic voltammograms as a function of A) cis-Re2Cl2 catalyst concentration (from 02 to 15 mM) and of B) CO2 substrate concentration (from 0 to 020 M) in DMF01 M Bu4NPF6 solutions glassy carbon disc ν = 100 mVs

Figure A12 Cyclic voltammograms as a function of A) trans-Re2Cl2 catalyst concentration (from 02 to 15 mM) and of B) CO2 substrate concentration (from 0 to 020 M) in DMF01 M Bu4NPF6 solutions glassy carbon disc ν = 100 mVs

A B

B

148

Figure A13 From the cyclic voltammograms in Figure A12 catalytic current is plotted versus [trans-Re2Cl2] (left graph) and versus [trans-Re2Cl2]12 (right graph) Despite the satisfactory linear fits obtained from these plots a slope of 1 from the log-log plot of the data confirms a first-order dependence on catalyst concentration as shown in Figure 7 of the main text

149

Figure A14 Plots of (iip) from linear sweep voltammograms at different scan rates for A) cis- Re2Cl2 (1 mM) B) trans-Re2Cl2 (1 mM) C) Re(bpy)(CO)3Cl (2 mM) and D) anthryl-Re (2 mM) in DMF01 M Bu4NPF6 under CO2-saturation conditions glassy carbon disc

150

Figure A15 A plot of TOF (s-1) vs scan rate (mVs) for each catalyst as determined from linear sweep voltammograms at different scan rates using equation 2 in the main text

151

A

B

152

Figure A16 Foot-of-the-wave analysis (FOWA) and associated plot of TOF (s-1) vs scan rate (mVs) for A) cis-Re2Cl2 (1 mM) B) trans-Re2Cl2 (1 mM) C) Re(bpy)(CO)3Cl (2 mM) and D) anthryl-Re (2 mM) from linear sweep voltammograms in DMF01 M Bu4NPF6 under CO2- saturation conditions glassy carbon disc TOFs were obtained using eq 3 in the main text

No significant differences were observed in the estimated TOFs from FOWA when using

1198641198641198881198881198881198881198881198880 rather than 1198641198641198881198881198881198881198881198882 in eq 3 except the TOF vs scan rate plots (Figure A16) were more well-

behaved before reaching the scan rate independent TOF maximum when using 1198641198641198881198881198881198881198881198882 Due to

slow catalysis following the initial overlapping one-electron reductions of the dinuclear catalysts

the linear portion of FOWA plots was used to estimate TOFs

153

Figure A17 Cyclic voltammograms of catalyst cis-Re2Cl2 with different proton sources in DMF01 M Bu4NPF6 under Ar and CO2 glassy carbon disc 120584120584 = 100 mVs A) 2 M H2O B) 1 M MeOH C) 1 M TFE and D) 1 M PhOH

C D

154

Figure A18 Concentration dependence of added H2O as a proton source A) Cyclic voltammograms of 1 mM cis-Re2Cl2 with increasing amounts of H2O in DMF01 M Bu4NPF6 under CO2 glassy carbon disc 120584120584 = 100 mVs B) A plot of icat (at -217 V) vs [H2O]

Figure A19 Accumulated charge vs time for representative controlled potential electrolyses in CO2 saturated DMF01 M Bu4NPF6 solutions (A) and with 3 M H2O (B) for 1 mM cis-Re2Cl2 1 mM trans-Re2Cl2 and 2 mM Re(bpy)(CO)3Cl in each condition Eappl = -25 V vs Fc+0 for electrolyses shown in A Eappl = -24 V vs Fc+0 for electrolyses shown in B

A B

B

155

Figure A20 Reported catalytic cycles for the ldquoone-electronrdquo bimetallic (top) and ldquotwo-electronrdquo monometallic (bottom) pathways for CO2 reduction by Re(bpy)(CO)3Cl in DMF 01 M Bu4NPF6 (protons originate from Hofmann degradation of the supporting electrolyte)

156

Figure A21 Proposed mechanism for cis-Re2Cl2 at Eappl = -25 V vs Fc+0 in DMF01 M Bu4NPF6

Table A1 Cartesian coordinates for optimized cis-Re2Cl2 conformer Element x y z 0 1 C -391636000 382735700 119805700 C -302739400 454311200 046141800 C -168639300 408595300 028795700 C -127708000 286813100 091980200 C -227732200 208775600 159392800 C -354047600 257490900 175320700

NN

NN

Re ReOC

COOCOC CO

O CO

O

NN

NN

Re ReClOC

COOCOC CO

Cl CO

NN

NN

Re ReOC

COOCOC CO

CO

+2e -2Cl__

NN

NN

Re ReOC

COOCOC CO

O CO

HO

NN

NN

Re ReOCOC

COOCOC CO

CO

+H+

H2O

+e_

CO

+

+CO2

+H+ e_

157

C -077160300 477758700 -050334900 C 006487600 248849400 086228800 C 099581500 324561900 015429900 C 055214500 436173400 -062064000 C 147247400 499725900 -150858500 H 111818800 582003100 -212174700 C 275737200 456515500 -160800600 C 322885500 352427100 -076246200 C 238896700 290155900 011245300 H -110491500 565232700 -105476900 H -493263100 418034200 133184300 H -332483200 547225900 -001423400 H -428238000 198617000 228129200 H 038676000 156342100 133033900 H 344363100 503031600 -230656100 H 427678000 324386200 -079653100 C 296645400 199017600 113276200 C 306219800 246210400 244171100 C 371050500 170417500 339523200 H 263246400 342742800 267794700 C 412207400 006437600 170819500 H 379426900 205276100 441850000 C -190412600 075823800 214395100 C -122878000 071429800 335861100 C -087644300 -050444400 390488000 H -100323200 164760100 385978900 C -182868000 -154626500 197717400 H -037060000 -056192100 486186700 C 427355800 049616300 301534400 H 479150700 -011549700 374166700 C -118413800 -165186200 320160400 H -092731600 -262283900 360166100 N 344347300 078610800 078825200 N -221412000 -036113300 146215700 C 468263000 -121922400 123421200 C 564240500 -193393000 194373500 C 470822800 -279372400 -045854400 C 612963900 -312011800 142344800 H 602264200 -156060800 288529300 H 430898800 -309237100 -141903600 H 687893800 -368721200 196401500 C -217262900 -275186700 119659200 C -154108400 -397400500 139447600

158

C -352479800 -366653300 -043649600 C -194390300 -507133200 065485900 H -071161600 -405304400 208368900 H -429497500 -349345400 -117621400 H -145165400 -602844700 078443400 N 423538900 -164599500 004135400 N -312778800 -259863700 026532700 C -297253300 -492115800 -026287800 H -332475000 -574942400 -086460900 C 565014400 -356243300 019920600 H 600056000 -448291800 -025034400 Re 272036900 -041875100 -096269800 Re -352531300 -054051200 -039886800 C -506380800 -019694100 064740300 O -600497300 002959800 128414800 C -464672300 -100582500 -185060600 O -534327600 -131415100 -271563100 C -354772200 122950900 -112956800 O -356469900 225551200 -164206100 C 214319700 -174227000 -220080100 O 184500600 -257598400 -293345300 C 395536900 025305400 -222238800 O 471925500 066998200 -298472000 C 141462200 074493100 -177433500 O 071273300 144975500 -233876800 Cl -145371700 -103168500 -166580100 Cl 129117000 -130290900 091136100 Zero-point correction = 0535847 (HartreePart) Thermal correction to Energy = 0582462 Thermal correction to Enthalpy = 0583406 Thermal correction to Gibbs Free Energy = 0452529 Sum of electronic and zero-point Energies = -3286154382 Sum of electronic and thermal Energies = -3286107767 Sum of electronic and thermal Enthalpies = -3286106823 Sum of electronic and thermal Free Energies = -3286237700 Table A2 Cartesian coordinates for optimized transition state (TS1) associated with rotational interconversion between cis-Re2Cl2 and trans-Re2Cl2 conformers Element x y z 0 1 C -429286500 441319400 087256100 C -313133400 492373300 038192600

159

C -195900000 411544100 029330500 C -201056300 276527600 074059700 C -323539800 227997400 130501100 C -434125900 307663000 135408100 C -078720300 455480200 -031391900 C -091383800 192406400 055228400 C 028552900 236170300 -001043400 C 031212400 371795400 -049678200 C 141166700 417247200 -128489400 H 141681100 520250800 -162759200 C 238403000 330567000 -165787000 C 238377100 198507300 -115195800 C 145126000 152280300 -026006200 H -074768200 556103900 -072172000 H -518884900 502219300 091388800 H -308598300 594808900 002528900 H -526384800 269529300 177986300 H -107625600 087239600 072127000 H 319092200 360623900 -231605400 H 317767600 133544100 -148729800 C 166568900 017104500 032663000 C 083790300 -039817200 130169000 C 090660100 -174802800 158156200 H 014346200 021211100 185224400 C 274872100 -187910100 011183800 H 023401300 -218222800 231200700 C -325103200 095002600 196684900 C -268940700 085130600 323949700 C -271875000 -035586600 390765100 H -223670200 173223800 367701400 C -387797600 -128297600 203281200 H -227605300 -045697400 489209100 C 181802900 -253488200 090095100 H 187675000 -360417800 105697400 C -334044300 -143553500 330088300 H -338450400 -238892800 380918300 N 273191800 -055339500 -010342600 N -379742500 -011323600 135839200 C 388693900 -261537600 -048501200 C 375145600 -389646500 -100348400 C 611445000 -254201500 -109367900 C 485485500 -450778900 -157629100 H 278591800 -438667300 -098764900

160

H 702076800 -195145800 -112917100 H 477042600 -550231800 -199962700 C -457999100 -238612400 133997000 C -492697200 -357742900 196918600 C -555822200 -310279300 -062897400 C -560132800 -455357200 125665600 H -468862300 -374378800 301082000 H -578995000 -287057900 -165997600 H -587601500 -548676500 173482100 N 505360900 -195562100 -052722900 N -490452700 -215700800 005609100 C -592222900 -431333600 -007064000 H -644926300 -504404700 -067091500 C 605864100 -381929000 -162081200 H 694321400 -425208500 -207046400 Re 503639900 010915900 022063100 Re -421400100 -028138900 -084674200 C -590499800 056725500 -076134600 O -693095300 109434600 -070145200 C -454494000 -079034400 -264414600 O -476642200 -113018900 -372133900 C -348286100 132570100 -159914500 O -308396700 226551900 -212036500 C 686960400 029089400 059967400 O 799483200 037477200 083118900 C 474271300 -037313200 202962000 O 457222400 -066371500 313458500 C 484235800 194729300 071906000 O 473779800 304548500 103486000 Cl -198959000 -142819900 -073260200 Cl 537290600 057551100 -219989300 Zero-point correction = 053634 (HartreePart) Thermal correction to Energy = 0582311 Thermal correction to Enthalpy = 0583255 Thermal correction to Gibbs Free Energy = 0453217 Sum of electronic and zero-point Energies = -3286126771 Sum of electronic and thermal Energies = -3286080802 Sum of electronic and thermal Enthalpies = -3286079858 Sum of electronic and thermal Free Energies = -3286209896

Table A3 Cartesian coordinates for optimized trans-Re2Cl2 conformer

161

Element x y z 0 1 C 293457600 -382925000 218716800 C 200117600 -449717300 145853300 C 099121400 -379273900 073679100 C 097006700 -236348200 078745900 C 195327700 -169662000 159258900 C 290208200 -241143000 226237000 C 004053200 -445631100 -003532800 C 003903100 -166704400 001930500 C -089307700 -233351000 -077338100 C -091005000 -376399600 -078151800 C -190228600 -444105200 -155311900 H -191531200 -552649000 -154428200 C -282196100 -374435000 -227059100 C -280011800 -232394400 -228194200 C -186579000 -163586800 -156483100 H 004477400 -554247000 -006177100 H 370808400 -436896600 272158600 H 201769800 -558117600 140283900 H 364200200 -189342300 286330600 H 005320400 -058308700 002275000 H -358581800 -426237700 -283901500 H -354956000 -178150200 -284697400 C -180437800 -015712500 -168081900 C -075555500 040430200 -240403800 C -070771200 177049700 -259144500 H 002499100 -023831100 -279035200 C -276026700 193272100 -137281600 H 012459400 222123900 -311770600 C 188974500 -022418200 176118800 C 082842800 031514700 248382100 C 076941600 167713400 269628200 H 005367200 -034205900 285589400 C 283164500 188070700 150203500 H -006699300 210960300 323190600 C -174301000 254265800 -209124000 H -173843200 361365800 -224254100 C 180096300 246922300 221756700 H 178266200 353754100 238467700 N -276140600 060463800 -112131700 N 285272700 055422200 123988200 C -391055900 269767500 -084191200

162

C -418376300 401060900 -121491400 C -580446800 264929800 048617400 C -530089800 464677400 -070302000 H -354538400 452799800 -191797700 H -643106200 206284700 114457500 H -552624100 566782800 -098924000 C 398114600 266032100 099104100 C 420569100 399259800 132519000 C 592087000 262096600 -027183700 C 532146700 464251600 082829000 H 352315600 452167500 197602300 H 657510200 203371400 -090260100 H 550446900 568134900 107815100 N -471761900 203549000 000374600 N 483883700 199052300 020123900 C 619973300 394326000 001391500 H 708761700 440612900 -039760700 C -613006200 395304500 016509100 H -702266400 440176400 058206600 Re -424749100 -006534900 043782700 Re 429141600 -004830700 -038442000 C 552391500 -089767600 077293700 O 627215000 -142377400 147896800 C 553011300 -020114700 -181327300 O 629930300 -026381400 -266788800 C 364327800 -176514700 -094323000 O 329941700 -278924800 -132749100 C -561825500 -033497100 172191100 O -645156300 -046342700 250625600 C -305427500 035205600 183695600 O -233004100 061407100 270575900 C -384948200 -192585300 068674700 O -364894900 -303371500 090533800 Cl 259414800 116406400 -177806100 Cl -576118200 -044335400 -150172000 Zero-point correction = 0537264 (HartreePart) Thermal correction to Energy = 0583698 Thermal correction to Enthalpy = 0584642 Thermal correction to Gibbs Free Energy = 0454402 Sum of electronic and zero-point Energies = -3286170118 Sum of electronic and thermal Energies = -3286123685

163

Sum of electronic and thermal Enthalpies = -3286122740 Sum of electronic and thermal Free Energies = -3286252980

Table A4 Cartesian coordinates for optimized transition state (TS2) associated with rotational interconversion between trans-Re2Cl2 and cis 2 conformers Element x y z 0 1 C 164149900 424804200 020481500 C 042174600 481821800 034732100 C -068267200 403155400 079298100 C -047703900 266220000 118859800 C 089554800 215186300 124762200 C 184634000 290820900 061214000 C -197132400 455354900 069881900 C -162925800 189597300 134261400 C -292245900 239902400 121236400 C -310856900 377484200 090204700 C -443171100 428347400 074569700 H -456381000 533084500 049308000 C -550830600 346606800 089407300 C -533050800 209804600 123073900 C -408262400 156542900 137984700 H -209107100 558997900 039543100 H 248062400 479465400 -020921200 H 024693700 585129200 006336500 H 286227700 254663700 055290400 H -155537200 083289100 144201800 H -651250100 384954900 075403900 H -620137700 146145500 134939400 C -392806300 017050600 186538300 C -443895100 -013983200 312343200 C -425142600 -140361700 364982400 H -496985900 062637300 367361000 C -302320900 -196020500 167870700 H -466549000 -166766900 461629100 C 123832800 072855200 156325000 C 040583100 -006125500 237889000 C 084769700 -123965100 294588400 H -057330500 027591600 266195900 C 297931600 -076899900 204917500 H 016822100 -183518700 354637200 C -351104100 -232111500 292633600

164

H -335072400 -331799000 331379400 C 217103200 -160645700 280023700 H 256737200 -251206300 324128800 N -326176100 -074648500 113724600 N 253527300 033867500 143683300 C -219944500 -288423700 086894500 C -158883700 -401284400 140313900 C -125288200 -330492800 -119809600 C -079651200 -480658400 059021300 H -171595800 -426605700 244739100 H -113184700 -297432300 -222076300 H -031355000 -568974800 099269700 C 441337800 -109627600 186683300 C 517754400 -165378700 288411400 C 623588300 -104717700 045051000 C 651742800 -191827100 265116100 H 473309500 -184284000 385334700 H 661636900 -076327400 -052191200 H 713640300 -234233900 343371500 N -202364400 -253955400 -041790800 N 493804900 -080385900 066907400 C 705596900 -161162600 141045200 H 810026300 -178795900 118629900 C -062468900 -444661000 -073624900 H -000277900 -502348400 -140806200 Re -300469300 -070894000 -111467100 Re 365676100 024509400 -076534100 C 246617600 -118734900 -109247400 O 173895800 -206600500 -128887400 C 459941500 -023034200 -231552700 O 519386400 -054906300 -325040500 C 260695300 138915300 -190320400 O 204658700 208792000 -261360100 C -289597900 -107064100 -297497100 O -281611400 -131703600 -409501000 C -133753500 017726600 -123634300 O -030515500 068245800 -134592200 C -390604900 091122300 -159694200 O -442013100 188190600 -192984400 Cl 518926700 210349200 -014822200 Cl -511364900 -202227800 -087281900

165

Zero-point correction = 0536558 (HartreeParticle) Thermal correction to Energy = 0582441 Thermal correction to Enthalpy = 0583385 Thermal correction to Gibbs Free Energy = 0455008 Sum of electronic and zero-point Energies = -3286119454 Sum of electronic and thermal Energies = -3286073571 Sum of electronic and thermal Enthalpies = -3286072627 Sum of electronic and thermal Free Energies = -3286201004 Table A5 Cartesian coordinates for optimized cis 2 conformer Element x y z 0 1 C 489187500 348157000 087304700 C 392244100 421857400 027202300 C 255890500 379303000 029289700 C 222527700 256256900 093951100 C 329200000 177748000 149850000 C 457190200 224297100 149351700 C 153846600 455322300 -027408300 C 088539700 219216600 104953600 C -014144400 300134700 056537300 C 019820400 419097700 -015411700 C -084587300 499398300 -070468500 H -057480700 587884900 -127211200 C -215037200 466292500 -052079900 C -249804000 351623400 023953800 C -153423300 270241300 076380300 H 179185100 546864200 -080160600 H 592442500 381041800 085304800 H 416796400 514935500 -022942300 H 536448400 163583700 191852800 H 063568200 125295100 152935900 H -294146200 526957200 -094589500 H -354481200 327662700 039100600 C -195076000 161302800 167952200 C -154084100 168755900 301342900 C -199393800 075985600 392586900 H -087653300 249003700 330787800 C -326939400 -023468400 216526900 H -167899700 080052200 496248600 C 295675700 048464000 214389600 C 291398300 041397400 353172400

166

C 252481700 -076457200 414154700 H 318440100 129031300 410734700 C 221563800 -170591100 196461300 H 250511300 -085103900 522225900 C -288731000 -020875000 349706500 H -326937700 -094012400 419593500 C 215026800 -183178400 334620000 H 184039900 -276255800 380068600 N -276643800 063123700 125481700 N 264603400 -057286700 137286800 C -425498400 -122028400 166572100 C -505735300 -197694100 251419900 C -526173200 -216914500 -018601100 C -597660000 -286041500 197591100 H -498915100 -185996100 358719100 H -532446900 -219813800 -126545500 H -661240600 -345107200 262545800 C 180452400 -280127200 105848500 C 113166500 -393460600 150080900 C 171623900 -355557800 -112185700 C 075818500 -490438200 058671400 H 089139700 -406301000 254748500 H 195457200 -335822100 -215813400 H 023621800 -579507100 091758100 N -436540200 -132088100 033151800 N 208383500 -261960800 -024185800 C 105759400 -471263000 -075198200 H 078225300 -543752200 -150722300 C -607962200 -296163600 059726000 H -679036400 -362889500 012649000 Re -318207500 005191600 -090245800 Re 320460400 -082468000 -080950400 C 171296600 010778600 -151915400 O 083185000 069834300 -197101400 C 364089000 -142001400 -255335100 O 388261500 -180867700 -361022400 C 430407800 068224700 -123095100 O 497806900 154914300 -156792800 C -368525300 -067691800 -257561100 O -400043600 -115515900 -357536100 C -166551200 -107227800 -089517600 O -076683400 -180086500 -085779600 C -225130300 138894000 -192868100

167

O -174774800 216733800 -259876700 Cl 509744200 -202982400 028933200 Cl -524670200 143332500 -066377800 Zero-point correction = 0536745 (HartreeParticle) Thermal correction to Energy = 0583152 Thermal correction to Enthalpy = 0584096 Thermal correction to Gibbs Free Energy = 0453952 Sum of electronic and zero-point Energies = -3286157474 Sum of electronic and thermal Energies = -3286111067 Sum of electronic and thermal Enthalpies = -3286110123 Sum of electronic and thermal Free Energies = -3286240267 Table A6 Cartesian coordinates for symmetric cis-Re2Cl2 (Cl in) calculated infrared spectrum in DMF Element x y z 0 1 C -364109700 392809100 129858000 C -265428200 466424000 068759200 C -133680200 413568100 053428300 C -103832200 281393800 105085800 C -212415800 203715900 158936400 C -337680000 260290500 173206100 C -033297300 484895800 -013918900 C 028559800 234952300 099515000 C 130736000 312118700 042536500 C 097623400 435666900 -024625700 C 198573500 502017200 -100864200 H 172619400 594299700 -153210600 C 325701600 450018600 -109429700 C 361174600 334178600 -035004200 C 267451700 268431100 042214000 H -058275800 580709700 -060248100 H -464173000 434233700 142914100 H -286224400 566716000 030823000 H -417855900 201521400 217870000 H 053425200 135090500 136070400 H 401763700 499920600 -169657500 H 464521900 299117800 -035495200 C 312687800 164363100 137874000 C 311022000 194682200 274723500

168

C 367444700 105989000 365829200 H 267059000 289005400 306942400 C 421754100 -038772400 181283200 H 367172400 128094100 472587100 C -189448200 063800800 202859400 C -104545300 040156600 311782800 C -082078600 -089737100 355650900 H -057079200 125261400 360499600 C -234352500 -165820700 184882000 H -014943400 -109805400 439139200 C 426548300 -010687600 317938900 H 473018000 -080841300 386926700 C -148696800 -193626400 291759200 H -134107700 -296019100 325324400 N 361569800 046488500 092653900 N -252169600 -038273400 137924800 C 478448200 -161395100 123093700 C 564432400 -247372100 192577800 C 496393800 -293935800 -068675700 C 616393900 -359435600 128432700 H 591840400 -226000500 295726500 H 466768900 -308132000 -172468400 H 683516800 -426945500 181561400 C -313243100 -271530100 119350300 C -309239200 -406086300 158483500 C -476396800 -321357900 -040772600 C -391331900 -499106800 095593600 H -242564400 -438386300 238128600 H -541012100 -283337400 -119654100 H -388444100 -603914300 125466500 N 445019700 -185488600 -006739700 N -395817400 -230747100 018921700 C -477483500 -455667300 -005421600 H -544535500 -524306100 -056981400 C 581898800 -383023800 -004897600 H 620478900 -468978400 -059567700 Re 303281500 -047802000 -098101000 Re -372302400 -026822200 -050957800 C -528387000 038786700 035808000 O -625704800 079384200 087174800 C -474311700 -048735800 -210315900 O -538100100 -063887200 -307217600 C -328664400 148573700 -117196100

169

O -302447800 251570500 -165060200 C 254921200 -161510000 -243676200 O 226774500 -233293100 -331577400 C 436845700 035668500 -204852100 O 518337900 088138600 -270731200 C 175901300 077419100 -169874300 O 101005500 150704800 -221095200 Cl -166998300 -118481200 -158643500 Cl 139887800 -153754300 058868200 Zero-point correction = 0514427 (HartreeParticle) Thermal correction to Energy = 0562481 Thermal correction to Enthalpy = 0563425 Thermal correction to Gibbs Free Energy = 0429315 Sum of electronic and zero-point Energies = -3287740995 Sum of electronic and thermal Energies = -3287692941 Sum of electronic and thermal Enthalpies = -3287691997 Table A7 Cartesian coordinates for symmetric cis 2 (Cl out) calculated infrared spectrum in DMF Element x y z 0 1 C -389621800 398237400 100661400 C -288429400 470904400 042505200 C -155308600 419498900 036969400 C -127374000 290724900 096972800 C -237220100 214814000 149778000 C -364403600 268450100 152678600 C -051191400 488481300 -027100600 C 005013200 244376900 100863500 C 110027000 317991300 044615400 C 080250500 439303600 -028274400 C 185310400 503964400 -100263900 H 162148500 594626900 -156614500 C 312832600 452334500 -099963300 C 344070000 337575800 -022079500 C 246196700 273162500 050982600 H -073356400 582368500 -078530900 H -491002800 438355300 104637500 H -308456500 568990400 -001188400 H -446458500 208660300 192492100

170

H 027056900 147873800 146793400 H 392135900 501075700 -156892500 H 446532100 300452800 -018624300 C 285809100 167385800 147461100 C 283546100 197944000 284235900 C 333843600 106749800 376418900 H 243742600 294402800 315564500 C 386003600 -039949300 192584400 H 332617500 128851200 483163800 C -210471900 081306600 209345000 C -151831500 077032500 336453400 C -126927900 -045352100 397445300 H -126993700 171078000 385530700 C -220629600 -152609600 202763200 H -081617800 -050511300 496460100 C 388731500 -012359800 329442900 H 431282000 -084233700 399190000 C -162969000 -161286600 329775600 H -146654700 -258259500 376194000 N 329834100 047090300 102976100 N -242153300 -032052800 141279600 C 441649900 -163554900 135173400 C 523847800 -251566600 206625000 C 462637400 -295390900 -056700100 C 575665900 -364238000 143333900 H 548795400 -231213800 310595200 H 435959100 -308424300 -161421500 H 639975400 -433220500 198023900 C -262907700 -272620200 128792000 C -242919700 -403150700 175807900 C -369542500 -355804700 -061913300 C -288405000 -511442900 101244900 H -191805800 -420529300 270234000 H -418826600 -332519600 -156109400 H -273107700 -613202900 137249800 N 411245400 -186570600 004431600 N -324776100 -250269300 009638100 C -353836300 -487227800 -019720900 H -391996900 -568449300 -081467200 C 544764400 -386370800 008950600 H 583558000 -472565900 -045185800 Re 281921800 -041341500 -094214000 Re -336262600 -044542500 -060694100

171

C -433660700 -082298300 -219856100 O -494004900 -107127100 -316968000 C -335129800 137677800 -121774800 O -331529500 243336600 -171322400 C 249981600 -144089700 -251797000 O 230624700 -209826900 -346593100 C 176194400 096089300 -177521900 O 112166100 175727500 -233689900 C 126616300 -117416900 -015155800 O 034011000 -166059300 037552900 C -177372400 -066891700 -163056100 O -085155200 -081059800 -233735800 Cl 497311500 054049700 -175854900 Cl -546896400 -032397900 073947000 Zero-point correction = 0514621 (HartreeParticle) Thermal correction to Energy = 0562664 Thermal correction to Enthalpy = 0563608 Thermal correction to Gibbs Free Energy = 0429354 Sum of electronic and zero-point Energies = -3287742226 Sum of electronic and thermal Energies = -3287694183 Sum of electronic and thermal Enthalpies = -3287693239 Sum of electronic and thermal Free Energies = -3287827493 Table A8 Cartesian coordinates for asymmetric trans-Re2Cl2 calculated infrared spectrum in DMF Element x y z 0 1 C 280502 -374458 237334 C 189857 -443833 160579 C 093574 -374858 080773 C 091585 -230185 083035 C 187307 -161367 165031 C 279204 -232344 239605 C 002437 -442911 -001466 C 000112 -161644 001885 C -089778 -229818 -081240 C -089379 -374475 -082618 C -182669 -442899 -166363 H -181848 -552121 -167294 C -272357 -372934 -243658

172

C -273467 -230790 -242386 C -184567 -160410 -163689 H 003537 -552290 -002918 H 354163 -427940 297472 H 190821 -553040 158689 H 351477 -178616 301165 H -000583 -052586 002543 H -343766 -426034 -306794 H -346199 -176303 -302681 C -179193 -012066 -171570 C -075510 046211 -245362 C -069429 184380 -259293 H 000436 -018155 -289470 C -270967 199209 -127769 H 012100 231052 -314518 C 181399 -013250 174061 C 074933 044786 243973 C 066630 183077 255407 H -001091 -019978 287235 C 272657 198523 131097 H -016959 229542 307702 C -169874 261374 -201679 H -168611 369562 -212899 C 167822 260574 199638 H 164654 368918 208805 N -273158 063512 -109015 N 277372 062513 115068 C -380623 275302 -065581 C -399648 412808 -084879 C -570507 266148 070560 C -507079 477035 -024052 H -331547 469549 -147960 H -636003 204141 131467 H -522557 583948 -038730 C 385248 274289 074096 C 401373 412566 090204 C 587084 262451 -043569 C 513510 475757 037357 H 327134 470757 144423 H 658245 198974 -096052 H 526663 583309 049383 N -466141 203316 012191 N 477856 200650 006491

173

C 608662 399042 -030246 H 698546 443657 -072628 C -594366 402181 055144 H -680137 447649 104561 Re -425318 -009497 035291 Re 430645 -008543 -028748 C 546974 -074260 106687 O 618165 -116127 189824 C 566807 -036898 -159347 O 651398 -051965 -238708 C 373985 -188219 -067681 O 344821 -297063 -097620 C -568593 -044284 156234 O -656654 -063439 230823 C -311608 020845 184524 O -243551 039427 278185 C -386445 -197334 049892 O -367718 -311061 067934 Cl 269061 084232 -195506 Cl -569935 -033825 -166663

Zero-point correction = 0514483 (HartreeParticle) Thermal correction to Energy = 0562698 Thermal correction to Enthalpy = 0563642 Thermal correction to Gibbs Free Energy = 0427710 Sum of electronic and zero-point Energies = -3287747424 Sum of electronic and thermal Energies = -3287699209 Sum of electronic and thermal Enthalpies = -3287698265 Sum of electronic and thermal Free Energies = -3287834197 Table A9 Cartesian coordinates for optimized neutral Re-Re dimer Element x y z 0 1 C -355240500 -413813000 077089800 C -443355600 -317443900 037084500 C -411299500 -178797500 051476500 C -287228200 -145337600 113854300 C -195753200 -248342600 153110200 C -229355300 -379434400 135079000 C -491285000 -075580200 001095500 C -250851500 -012365100 127369400

174

C -326889000 089487000 072061600 C -449904300 058070700 006544500 C -522519500 165422300 -054036000 H -615844600 143354400 -105047900 C -473947400 293010900 -050989600 C -350872900 323688900 014565000 C -278787600 224619600 074669000 H -584764300 -100255200 -048625200 H -379375000 -518668100 063003600 H -537456900 -344986500 -009661100 H -159634900 -458094800 162335900 H -156557600 011334700 174498500 H -528690500 373089200 -099627500 H -314268700 425930800 015111100 C -156741300 248827200 156445100 C -176592800 295738800 285243100 C -069996100 302101700 374906500 H -277219100 322349100 315399500 C 072007900 224897000 196852000 H -084891700 335417600 477044400 C -068381200 -205297100 217732200 C -066064500 -199313200 356010100 C 047187700 -152079900 422599600 H -154941700 -229234400 410335300 C 153867000 -134297500 207905700 H 048473500 -142563200 530632700 C 054758500 265046900 329982200 H 139859000 270242000 396590300 C 158105500 -120702300 347322000 H 248923700 -086753800 395509900 N -033096800 212398900 110562500 N 038858000 -166951400 141686800 C 204215000 204382800 139517100 C 323247000 220898300 212048100 C 326691500 177824800 -056792800 C 444899400 217091500 147538000 H 319768200 238281800 318852600 H 324539200 160406400 -163560500 H 537311700 231070900 202531900 C 273603100 -123579400 125655300 C 403109800 -115628200 178779500 C 361462700 -135020300 -089600000 C 512711800 -120123300 095200200

175

H 417582000 -109272500 285861800 H 341057100 -142641900 -195675700 H 613228300 -116527300 135759500 N 205513400 180498600 005420800 N 252937900 -134839100 -008315400 C 490781200 -129190900 -042655800 H 572992700 -132602400 -113207700 C 445574000 196995800 008748200 H 538073000 194379600 -047648100 Re 020958500 163527400 -098291800 Re 054553700 -171727900 -078373000 C 063024200 -360164700 -077236800 O 066380600 -476591200 -076787900 C 101402500 -172802900 -262963500 O 134083400 -180091700 -374209100 C -126991500 -184001500 -140769000 O -231940300 -196780700 -187990100 C 102596100 131429800 -267024200 O 158700000 119960300 -368300700 C -005519800 344251700 -146402300 O -023008700 454826200 -178487500 C -148130700 120882800 -180567800 O -247001600 099291700 -236813200 Zero-point correction = 0533275 (HartreePart) Thermal correction to Energy = 0575610 Thermal correction to Enthalpy = 0576555 Thermal correction to Gibbs Free Energy = 0458127 Sum of electronic and zero-point Energies = -2365184572 Sum of electronic and thermal Energies = -2365142236 Sum of electronic and thermal Enthalpies = -2365141292 Sum of electronic and thermal Free Energies = -2365259720

Table A10 Cartesian coordinates for optimized one-electron reduced Re-Re dimer Element x y z -1 2 C -511334400 -221363500 -090608100 C -540924600 -088854600 -076539900 C -454503700 -002282700 -002276300 C -337300200 -058955600 056882600 C -310515100 -199547400 043332400 C -395656600 -277953100 -029024300

176

C -478306000 134819900 012497500 C -247871300 023534400 123863300 C -266897700 160833600 130352900 C -386114700 218399900 076389400 C -401002700 360456800 083129900 H -491190700 405709500 042730400 C -301319900 438329500 134595100 C -180328500 380476100 183449000 C -162780500 245034300 181621800 H -567455200 178374300 -032113200 H -576178100 -285522900 -149538600 H -629252100 -046638100 -123753300 H -374861200 -383948300 -040282700 H -157109600 -018456200 164986600 H -312163800 546371200 136310200 H -100598700 444872900 219305500 C -038787500 180381100 234238500 C -033725900 153444700 369210400 C 078786400 087300400 423406200 H -118674600 180331900 430918700 C 179851200 099288900 204363000 H 080928400 058089400 527919700 C -198261000 -254424600 124410500 C -233698800 -318558800 240950400 C -134332300 -354105400 334987500 H -338890900 -334710600 261397900 C 029596900 -263543800 182059300 H -160949200 -402304700 428515800 C 184750200 061863400 341002400 H 273132500 011849400 378858800 C -004437900 -324012700 305685500 H 074155500 -349371200 375750800 N 062158700 146762400 147821900 N -068142600 -227059400 090336200 C 292952500 092962800 118772100 C 425755500 071075400 163946300 C 374368000 119314900 -099902100 C 530737600 075148100 076344200 H 443855200 053742100 269354100 H 350301800 138107500 -203900500 H 632356000 060084300 111479100 C 164119100 -245308000 140926600 C 277067000 -274305500 222144700

177

C 308379200 -198527300 -038132100 C 403395400 -268632500 170263900 H 262547400 -301810900 325939400 H 317936900 -166104100 -140950800 H 489714900 -290917100 232232200 N 268886900 120024300 -014311900 N 181279900 -202232700 011122700 C 419311300 -231817800 034441100 H 517140000 -224605700 -011484700 C 504148500 098267200 -060898700 H 583323300 100229400 -134901500 Re 071456600 180018900 -068184800 Re 007988200 -163794500 -105107900 C -025212800 -332847000 -179737100 O -046079800 -436739600 -229186500 C 107400000 -115332900 -259919200 O 173466400 -094726600 -353910400 C -149934700 -098124500 -193354400 O -242490100 -061231200 -253050300 C 109743200 196991000 -253952700 O 135577200 213644700 -366314600 C 091707100 365383400 -049611400 O 102476200 481202300 -037696900 C -110368000 209307700 -122570000 O -215003300 233181400 -166971500 Zero-point correction = 0529699 (HartreeParticle) Thermal correction to Energy = 0572441 Thermal correction to Enthalpy = 0573385 Thermal correction to Gibbs Free Energy = 0453371 Sum of electronic and zero-point Energies = -2365252805 Sum of electronic and thermal Energies = -2365210063 Sum of electronic and thermal Enthalpies = -2365209119 Sum of electronic and thermal Free Energies = -2365329133 Table A11 Crystallographic data for trans-Re2Cl2 (CCDC 1578651)

Moiety Formula C40H22Cl2N4O6Re2 2(C3H7NO) [+solvent]

Formula Weight 128888 gmol T (K) 100(2) λ (Aring) 071073 Crystal System Space Group Triclinic P-1

178

a (Aring) 15797(5) b (Aring) 16298(5) c (Aring) 20698(5) α (o) 68843(5) β (o) 74058(5) γ (o) 76127(5) V (Aring3) 4719(2) Z 4 ρcalc (gcm3) 1814 micro (mm-1) 5301 F(000) 2506 θ range for data collectn 155 to 2537o

Index ranges -19 le h le 18 -19 le k le 19 -24 le l le 24

Reflections collected 41094 Independent reflections 16724 [R(int) = 00188] Completeness to θ = 2500o 968 Max and min transmission 0333 and 0504 datarestrparams 16724 0 1161 GOF on F2 1036 Final R indices [I gt 2σ(I)] R1 = 00237 wR2 = 00564 R indices (all data) R1 = 00277 wR2 = 00579

179

Figure A22 NMR Spectra

6971

7375

7779

8183

8587

8991

9395

9799

101f1 (ppm

)

201

214411395206

206

206

200

104

105

732732732733733733733734734756756757758759759767767768768768769769770770771774775775775775776776776777777782782782783784784797797797798798799827828861861861861861862862862862883980

NN

NN1

180

110115

120125

130135

140145

150155

160165

f1 (ppm)

11861

11996

1236112384124921255012691127381290612914

13155

137011378513798

14901

1545215489

15760

NN

NN1

181

7374

7576

7778

7980

8182

8384

8586

8788

8990

9192

93f1 (ppm

)

199

195

416

108

201

220192

192

200

096

200

753754760762

773773774776783788790791

834835837838840

868869876878

887

903904

NN

NN

ReRe

ClO

C

COO

CO

CCO

ClCO

cis -Re2 Cl2

182

DM

F

120125

130135

140145

150155

160165

170175

180185

190195

200205

f1 (ppm)

12404124941259312610126821283212848128711287713102131421315713190133411407714111

15410

1575715822

16187

1950719509

19947

NN

NN

ReRe

ClO

C

COO

CO

CCO

ClCO

cis -Re2 Cl2

183

7172

7374

7576

7778

7980

8182

8384

8586

8788

8990

9192

93f1 (ppm

)

088

098099106

198

328

099

088

300

107

088092

090095

084

092102

733743744748750752753755764765769771772774775781783784800802803

834835837840842843856858860862872873876878

887

897899900901

trans-Re2 Cl2

NN

N N

Re Re

OC

OC

OC

OC

Cl

Cl

OC

CO

184

105110

115120

125130

135140

145150

155160

165170

175180

185190

195200

205f1 (ppm

)

12392124391244212590126011261212667128511286112881129281303713057130921315013160131911332213331139591405914091141121413614180

154091542015706157601578315790162451624816315 DMF-d7

19096191951948419514

1988319936

DM

F

trans-Re2 Cl2

NN

N N

Re Re

OC

OC

OC

OC

Cl

Cl

OC

CO

185

6970

7172

7374

7576

7778

7980

8182

8384

8586

8788

8990

9192

9394

f1 (ppm)

202

112

108

102

103110108

107109104

098

097

100101096

747748749750753755756764766766767772774784786791792793793794795799801812814817818820823824840842

851853

872875876884

NN

2

186

114116

118120

122124

126128

130132

134136

138140

142144

146148

150152

154156

158160

162164

f1 (ppm)

1195712107124791248612550125691262612643127131277812826129061294112973131491319813216

137891383213887

14984

1554915582

15847

NN

2

187

APPENDIX B

188

Table B1 Photophysical properties of Re complexes in dichloromethane solution Complex 120582120582119898119898119888119888119890119890119888119888119887119887119886119886 119899119899119899119899

(log ε)

120582120582119898119898119888119888119890119890119890119890119898119898 119899119899119899119899 λ1 λ2

ℎ120596120596 119888119888119899119899minus1

λ2

τ0 (N2) λ1 ns λ2 micros

TA max nm (rel inten)

anthryl-Re 252 (480) 296 (415 366 (398)

570 688 764 1440

420 6 23

430 (1)

cis-Re2Cl2 258 (485) 296 (442) 380 (412)

592 700 776 1400

210 15 65

440 (1) 520 (1)

trans-Re2Cl2 258 (470) 296 (427) 376 (395)

598 698 772 1370

200 15 90

440 (1) 490 (095)

[(dphbpy)Re(CO)3Cl]a 384 630 --- 56 --- --- Anthraceneb 340

355 375

375 670 ---

6 3300 410 440

Figure B1 Absorption and luminescence spectra of anthracene containing rhenium complexes (cis-Re2Cl2 trans-Re2Cl2 and anthryl-Re ) in deoxygenated CH2Cl2 at room temperature

189

Figure B2 Stern-Volmer quenching plots of tau(0)tau versus the concentration of BIH in DMF solution for (A) anthryl-Re (kq = 22 x 107 M-1 s-1 average of quenching of both emission lifetime components) and (B) trans-Re2Cl2 (kq = 51 x 107 M-1 s-1 )

190

191

192

Figure B3 Example GC trace for a photoreaction with trans-Re2Cl2 at 01 mM concentration The FID trace (top) shows CO at 212 minutes retention time and only trace other products (CH4 RT = 388 min) The TCD trace shows only trace reactivity (H2 at 096 min and O2 N2 at 172 min) and is a zoomed in y-axis range with the tallest peak at the top of the spectrum

Figure B4 Example 1H NMR formate analysis with ferrocene as an internal standard at 418 ppm and formate as an analyte at 863 ppm This example is for a photoreaction with trans-Re2Cl2 at 01 mM concentration The ratio of the peaks is 201 which is 7 TON of formate for this catalytic reaction

Table B2 Photocatalytic reaction TON TOF and quantum yield values

Complex concentration (mM) max TON (CO) max TOF (h-1) max φ () anthryl-Re 005 34 43 06 anthryl-Re 01 38 43 11

193

anthryl-Re 02 20 30 14 anthryl-Re 05 16 18 26 anthryl-Re 10 12 12 29 cis-Re2Cl2 005 95 128 16 cis-Re2Cl2 01 78 105 26 cis-Re2Cl2 02 52 71 34 cis-Re2Cl2 05 31 37 43 cis-Re2Cl2 10 17 20 44

trans-Re2Cl2 0000001 400000 2500 --- trans-Re2Cl2 005 105 158 16 trans-Re2Cl2 01 63 92 22 trans-Re2Cl2 02 28 38 19 trans-Re2Cl2 05 27 30 40 trans-Re2Cl2 10 16 15 44

Re(bpy)(CO)3Cl 005 16 17 02 Re(bpy)(CO)3Cl 01 21 23 06 Re(bpy)(CO)3Cl 02 43 30 20 Re(bpy)(CO)3Cl 05 24 21 31 Re(bpy)(CO)3Cl 10 19 16 46

Figure B5 Plots of absorbance at 370 nm as a function of concentration in DMF solution for A) Re(bpy)(CO)3 Cl and B)anthryl-Re

194

Figure B6 Plot of quantum yield versus catalyst concentration Conditions DMF containing 5 triethylamine 10 mM BIH irradiated with a solar simulator (AM 15 filter 100 mWcm2)

195

APPENDIX C

196

Table C1 Cartesian coordinates for each structure (angstroms) 1 Structure DATCE

x y z N -133864176 006926695 -114312768 C 099088925 004023018 -131120181 C -116956186 003552746 030082774 C 106715286 000649245 019109078 C -001169499 076534992 095553982 C -003304746 -075432605 092246419 H 149665296 091842294 -171849322 H 147209334 -083325911 -175658917 H -212382007 003793455 080657989 H 206011534 -001692376 062685603 H 002480233 145217907 178253877 H -001637538 -147721994 171879339 N -036841473 007142519 -187093878

2 Structure DAP1

x y z N -124321604 012574799 -103812397 C 103742003 -021093599 -130370796 C -125653994 -075852501 006709400 C 154057300 032737800 000317100 C 086407501 004521700 115865898 C -038955301 -073746699 113297999 H 172502697 000448500 -211670709 H 088891202 -129329300 -124131298 H -217757297 -132030404 013091099 H 243005109 094322199 002128800 H 124473500 038176200 211456299 H -066945100 -129520500 201813602 N -023882701 043701500 -164848804

3 Structure DAP2

x y z N -116779101 -064002001 -108525395 C 068300301 075432998 -125431597 C -147904301 -010512900 018798700 C 148783505 028317201 -007852600

197

C 086488998 -000468100 110520506 C -060514897 007661000 123283005 H 006928100 161709297 -097713298 H 132201004 103113604 -208814597 H -254451108 -006943700 036536899 H 255957389 017099699 -017685100 H 144391096 -028888100 197464800 H -102901101 024935301 221440911 N -019210300 -032655400 -173923600

4 Structure NdisTS

x y z N -130195343 001342211 -108620119 C 105292690 007258783 -129336417 C -121845627 -064856392 012370900 C 128874016 -029430455 015287189 C 070504355 052046371 127374268 C 004811408 -079807019 092320359 H 164533305 094120276 -158244169 H 138154840 -075137752 -193326998 H -217247462 -090840471 055546230 H 223382282 -078592616 035617012 H 114248049 083859372 220771027 H 011646657 -164245570 159758270 N -031415167 037006265 -172467542

5 Structure CdisTS

x y z C -123991597 000001755 -108678555 N 111064184 012755996 -117369318 C -122954774 -088036704 012311003 C 120902181 -022120188 022741903 C 050301600 057922471 129399884 C -000173660 -081041926 099546325 H -217851353 -115399027 056738806 H 219879723 -058687681 046176511 H 089500433 100905406 220304942 H 016966029 -161051345 170529115 N 005061551 021945223 -175495827 H -189900517 -040604001 -185402000

198

H -162471807 100128031 -085891795

6 Structure NconTS1 x y z N -129244304 007636036 -101047087 C 104163992 014488558 -126618493 C -116634893 -075647867 013728587 C 126299679 -010212760 020811179 C 059815705 067613679 121299589 C -012937532 -067258233 108854246 H 165934813 096744531 -162766850 H 131439888 -073823875 -184796941 H -203141189 -138707054 028535643 H 198126447 -085941786 049409425 H 003639345 152687764 083496058 H 002891397 -146834338 180330479 N -033586344 048483324 -164720857

7 Structure CconTS1

x y z C -123598480 002076247 -107024336 N 111656094 021811867 -117233992 C -121964467 -075743264 021374667 C 120177174 -011838255 021241990 C 055813766 068511385 123024774 C -010755118 -071358263 108197474 H -208826065 -136226428 044462928 H 203538108 -075830472 046382228 H -002436638 151902115 084208316 H 009314413 -149601495 180005956 N 004187234 033545503 -172625780 H -178527188 -054973620 -182126570 H -176637816 097401685 -099474645

8 Structure NconInt

x y z N -117254436 -012935539 -103004634 C 114911330 052507800 -132641387 C -120073497 -078021890 027967709

199

C 134310114 -015687630 -002968836 C 069569921 037333986 107144785 C -048748320 -048004261 141496575 H 133888507 159884501 -131786120 H 169165754 009332362 -216674495 H -209250116 -139012527 032793716 H 135121119 -123951328 -009737577 H 064599955 144558704 123436141 H -081668174 -079587555 239674282 N -030165136 040838382 -168327153

9 Structure CconInt

x y z C -106391704 -029168245 -109964263 N 117967534 059556657 -125672734 C -127702379 -075489688 035226682 C 128607547 -017518854 -005344008 C 069972783 031735843 108559728 C -049822330 -051729470 145452821 H -222556758 -127307343 047208774 H 133984542 -124352431 -022866115 H 064357913 139016211 123451269 H -080712503 -080358273 245123553 N 004665386 053191787 -169741893 H -108687139 -117469788 -174655640 H -195164299 027860880 -137835872

10 Structure NconTS2

x y z N -122473168 -045778599 -113910139 C 094505334 056573945 -136906683 C -131874728 -057033855 028926978 C 141338336 001856516 -006715097 C 073123562 049870428 117475450 C -057058573 -001180191 135865033 H 081215769 165091348 -134124863 H 163488150 034631550 -218331766 H -227999783 -100280988 053255856 H 165092111 -104281521 -007590441 H 117330158 121783650 185320687

200

H -107045138 005085879 231917119 N -035554022 002986831 -183606148

11 Structure CconTS2

x y z C -098741549 -043501547 -114645267 N 094523656 090839851 -108737504 C -130527937 -063195413 032575455 C 141925013 -005428514 -013735721 C 086732721 010182675 124706852 C -047469309 -034508145 142275000 H -230822897 -098507929 053027695 H 153624642 -106233335 -052521968 H 140002048 063613701 202032113 H -090457594 -039136788 241618919 N -017153913 074174345 -153880131 H -052493757 -132949257 -157737041 H -192843127 -029718637 -167398417

12 Structure DATCA

x y z N -142293572 019845748 -114382577 C 097666281 011770615 -138115907 C -121422291 012395849 027996346 C 103657210 -002077130 013112727 C 000653699 074467486 095053643 C -011138921 -077785206 080267608 H 123057044 114303195 -166671002 H 170794582 -053806341 -185897791 H -214152622 014866386 084120041 H 202121615 -012557875 057551348 H 011214472 131699753 185691321 H -011495087 -153014958 157237792 N -033029807 -022865683 -192299938 H -165234458 113811672 -141621232 H -040628135 -122710514 -198618388

13 Structure DHDAP1

x y z

201

N -139481902 023868400 -113966894 C 097603899 030155301 -136241305 C -174704099 -015927500 015561500 C 139266598 020351399 008435500 C 060675901 -013192300 115226996 C -086680102 -037098899 117894304 H 091113198 134645605 -166934705 H 175735795 -015404899 -197798204 H -281018090 -026625401 033284000 H 244280696 039425400 028221199 H 109289396 -019347601 211922097 H -128807199 -067126000 212922502 N -026623699 -035127199 -172259498 H -215979195 018431900 -178064704 H -021916100 -132326603 -145930195

14 Structure DHDAP2

x y z N -136570203 -032421601 -111690795 C 093440503 044240099 -136343503 C -152962899 -009297200 024612100 C 158951902 021596000 -002402100 C 088892901 -002088400 112418401 C -059541303 -003583700 124591005 H 050688398 144633996 -142015803 H 168743205 038124600 -215160894 H -257504106 -001370400 051987100 H 267274308 022763000 001977000 H 144114602 -016861600 204503012 H -099180698 003722700 225064707 N -012575100 -050236100 -171296000 H -198272002 020465900 -169944596 H 017379400 -144221604 -152972806

15 Structure NdisTSprime

x y z N -142339540 -014606592 -116566598 C 093296069 025221679 -126147401 C -140808904 -032721406 022840041

202

C 119161737 -016610871 018556029 C 084130841 081545776 126951730 C -012877002 -034134027 101129293 H 080472010 133444512 -132227707 H 179706573 000164181 -187867403 H -235516500 -018690881 072857887 H 200624251 -086340731 035096633 H 139543521 092786473 219372249 H -011925846 -106822538 181810999 N -023407100 -035943642 -187034750 H -186182213 070168203 -147589076 H -010957908 -135344136 -195132947

16 Structure NdisTSPrime

x y z N -135345852 020459662 -105027461 C 104206014 013321534 -134365678 C -122168159 042395344 033541670 C 128673506 -014588186 012525053 C 006758421 005781965 105366910 C 060426700 -132363117 078441113 H 115246558 120371866 -153755569 H 177541852 -038642454 -196429086 H -215312290 039689919 089210719 H 225471497 014308731 052221948 H 021058591 051497751 202611446 H 094744480 -210143733 144823039 N -027236584 -028958043 -179056585 H -177515674 097728574 -153008449 H -032491049 -129297805 -174940085

17 Structure CdisTSprime

x y z N -139562595 013293861 -109109366 C 099973285 019917566 -139172935 C -128806067 019103202 034260291 C 129041827 019030157 008237755 C 011506672 024624294 103696835 C -077405405 -098817056 111280930

203

H 101604879 123224723 -176587749 H 177840137 -033207700 -194385386 H -209643722 075877380 078947771 H 225147820 055132854 042733517 H 023269734 084052205 193693876 H -118028319 -148607981 198114049 N -027926472 -037997854 -177376115 H -158354163 104699314 -146162188 H -027862626 -137567961 -164485288

18 Structure CdisTSPrime

x y z N -133637977 031465718 -109704268 C 101107061 -003348709 -149189413 C -125072801 000064490 030805078 C 125051641 -057820606 -011412560 C -046861416 089247489 124482906 C 012283386 -045685077 088532895 H 123931909 103968787 -152898061 H 167403328 -051324832 -221523738 H -213566422 -048302138 070886517 H 226258874 -067250121 026165459 H -074728137 125632071 222391558 H 010247264 -120793450 166828823 N -035648748 -020929363 -195280385 H -139411724 130264926 -125304103 H -055888206 -118373179 -208697677

19 Structure NconTS1prime

x y z N -143094933 000844477 -105635679 C 098796737 019592127 -131666112 C -139533913 -048966303 027399421 C 113849020 -002605952 017835093 C 054325736 089400637 112329757 C -024462490 -043452144 110718977 H 113207793 126165700 -151517606 H 175230050 -034002155 -188157892 H -231300664 -094758868 062348062

204

H 186804652 -073859274 054489440 H 004017371 175133789 067512351 H -011543095 -115248680 190509605 N -030366421 -020636971 -186336851 H -177593493 094211507 -117049420 H -029553342 -118461883 -208670139

20 Structure NconTS1aPrime

x y z N -133736515 032192284 -107347786 C 103748357 012912646 -138524425 C -117192423 027935398 033617321 C 119287157 -022303137 007880460 C 008648123 024252611 106512630 C 036466718 -124542284 081046021 H 127329171 118689895 -154016256 H 173719871 -044634843 -199471390 H -210495520 035779929 088236797 H 218828321 -010601499 049635628 H 026318210 073956609 201055074 H -031991121 -201209474 047015148 N -029615569 -013984543 -188805306 H -160875452 124218035 -137538707 H -042383334 -113234615 -197748208

21 Structure NconTS1bPrime

x y z N -137007999 021642189 -103387082 C 101358879 009395494 -136566508 C -117764771 048460183 031954116 C 124384856 -023482305 009737201

C -016166560 -002143468 113447988 C 062831956 -134321129 076988173 H 116087043 116113365 -154630864 H 172647870 -044072470 -199733388 H -194308221 112372172 074224061 H 196049356 037644607 063625616 H -003499719 042012647 211345911 H 005090978 -197989404 009782664

205

N -032054877 -028873754 -181068313 H -182399678 097171456 -150863016 H -039848125 -128864574 -180960560

22 Structure CconTS1prime

x y z N -139204526 012252544 -107907808 C 100119078 018888251 -136349821 C -123541296 007381579 034205797 C 120927906 034241784 012560329 C 012075529 046527982 106624746 C -047619471 -097196239 105428267 H 114950013 118056560 -181362844 H 177378404 -044973451 -179583240 H -208996129 046395597 088231999 H 222906733 050248492 046082073 H 016861869 106601584 196488047 H 002724839 -182898188 061913151 N -028030020 -032539827 -180860305 H -162760043 104729223 -139249980 H -029082894 -132732880 -178085411

23 Structure CconTS1Prime

x y z N -137918520 033643577 -115644407 C 100732672 -002059591 -145013666 C -121840417 020094195 026702461 C 119852984 -057649338 -005059063 C -036758199 105796087 107098007 C 020355304 -038456950 094631630 H 127565694 103581023 -152903795 H 167146790 -055035418 -213445640 H -198380148 -037611693 077261817 H 207487488 -117643464 016400950 H 016595033 183800828 053014487 H 009975848 -107083881 177547991 N -034726137 -019532865 -196000302 H -146424091 130922759 -139181232 H -053978330 -117438269 -207429242

206

24 Structure NconIntprime

x y z N -128932583 004634845 -094741422 C 105325341 043676457 -145664108 C -146003604 -052121627 036293334 C 130981970 -001541957 -004763298 C 055006790 056903785 094047529 C -060538483 -029326814 141034186 H 090941447 151290190 -153617311 H 179818821 012317528 -218886948 H -240994430 -102145517 052036697 H 146781588 -108894932 003664571 H 032035694 162774205 085257143 H -082317519 -063420898 241286302 N -020619182 -024174021 -181216311 H -212495565 -004916412 -148585749 H -003512795 -123532736 -182547951

25 Structure NconIntaPrime

x y z N -137069941 021131562 -103988624 C 100963295 011624040 -133453441 C -118363142 048190045 030083588 C 121398103 -023436050 012861913 C -009080713 006123838 107631958 C 059785086 -138143158 078924429 H 115093708 118764114 -149759293 H 173718333 -040411642 -196020043 H -199088168 104974210 074667197 H 204001880 025811371 063253444 H 003969629 049962756 205413985 H -001792898 -197598946 010731504 N -031133908 -026844308 -181672335 H -188871181 091863626 -152220869 H -037918606 -126993549 -182709599

207

26 Structure NconIntbPrime x y z N -104582500 059907800 -092982298 C 112143099 -027352500 -159853399 C -131762600 033106801 043827900 C 133090401 -005010000 -012573899 C -053163302 -034339300 134496295 C 071292698 -093837798 073650700 H 154193902 052914703 -220309305 H 150284600 -122447503 -197357702 H -225413203 076937902 076498801 H 125982904 099320900 016193600 H -089276499 -050508499 235211492 H 071693301 -200454593 051811498 N -035087201 -030252901 -177176297 H -185938799 091630900 -141344297 H -065715700 -123778498 -155890298

27 Structure CconIntprime

x y z N -154577303 -025488600 -120525801 C 083828998 045557699 -126606703 C -138421094 024584199 010359800 C 132028306 045265099 020247300 C 065373802 000839900 131776595 C -070212299 -056299299 098760098 H 060008001 148591697 -154562104 H 170390201 018555000 -187536299 H -132234395 132455599 022982199 H 233072495 083782601 031872499 H 113432896 -002192400 228807902 H -078386301 -163970304 087174499 N -023806199 -041413799 -176581800 H -205685401 036631000 -180326200 H 001652400 -137323594 -161801803

28 Structure CconIntPrime

x y z N -150680757 056806660 -130433857

208

C 090254611 -013684431 -134248567 C -133901668 018480022 005263753 C 122509563 -068525136 007712884 C -045107952 076213592 092525667 C 066651374 -021551019 124015796 H 128556395 088743246 -137062228 H 151083350 -069635767 -205396152 H -155124116 -086979580 018505041 H 208378029 -134905469 012883927 H -018387491 181044579 081894964 H 104705095 -047549337 222000599 N -043426350 -010652254 -197062349 H -136226058 155375171 -143762600 H -075494838 -103908885 -215765285


x y z N -129345250 -014148657 -106223071 C 098298764 052225679 -143695927 C -143154299 -046441698 030293703 C 148590040 008770845 -008607526 C 072291613 046808505 114760506 C -057767862 -012477954 135393023 H 063843900 155562139 -14422717 H 175030959 040812740 -22049365 H -242516923 -081648183 055104113 H 181810308 -095227081 -008509157 H 110098279 120245564 184719050 H -099238783 -019823252 235249138 N -013304961 -033549953 -182581079 H -207761145 -044912961 -159773958 H 016546376 -129778743 -175358987

30 Structure NconTS2Prime

x y z N -095442176 070564193 -090830022 C 109275067 -032066563 -159886014 C -129964244 034616992 040946886 C 153150833 -012862645 -017070051

209

C -051763374 -047516546 124236357 C 080180967 -090327680 089841759 H 152177787 045718437 -223145628 H 141152573 -128543031 -200184107 H -224236107 073953104 076580024 H 177199173 089397639 010826312 H -098024762 -082737643 215669823 H 125232351 -175105810 139811301 N -036664572 -028272822 -171884358 H -172617841 110976660 -139820719 H -073830664 -118157279 -145777547


x y z N -148091173 -032316923 -122846985 C 079944986 056121582 -126692426 C -160111916 018489447 007896924 C 131259978 044162902 016073807 C 061332721 -014667325 123267162 C -076902974 -047871113 114310205 H 038076660 155287719 -145944369 H 166327238 047200024 -192983472 H -180307865 124826133 020540553 H 234386492 073415506 032333699 H 116880322 -040741485 212682962 H -121259475 -119246519 182513130 N -016046345 -043579715 -172102416 H -201503134 020841511 -188836086 H 016917495 -135795736 -150161695


x y z N -137026465 073302871 -128783345 C 087258899 -026980808 -142273438 C -154870033 032182592 005344129 C 116283774 -062507212 003527457 C -060129660 069691128 116412342 C 062601334 -001556111 119647968 H 141744506 066357487 -160980988

210

H 135420501 -101914442 -205298281 H -188953984 -070950902 010131884 H 209415388 -116732562 016407259 H -087284940 139373589 194623566 H 121124625 -005525590 210910273 N -046208549 -009558035 -198351347 H -105760002 168298090 -136993039 H -091536391 -098043090 -211986423

33 Structure TATCE

x y z N -124102449 006335469 -116420841 N 098353422 021775147 -121458483 C -114219677 004522111 028056934 C 106271446 005945647 020733991 C -001450774 076942956 099471682 C -001210226 -075345653 091220111 H 168854368 -022541514 -176783109 H -211477113 001972986 074835366 H 207657313 005117608 058292556 H 000053438 146258247 181677806 H 000012857 -153649640 164929664 N -022080594 009270635 -182924676

34 Structure TAP1

x y z N -125923800 -001367800 -106760204 N 093691301 -049631900 -111592805 C -135856998 -051352400 025779101 C 145615697 030840701 -006771700 C 078232801 044971099 110806799 C -052416301 -021822999 129869795 H 159358597 -054096001 -187049699 H -230729604 -100040996 043006501 H 240791202 079541701 -023728800 H 121059501 104139698 190509200 H -083647400 -048687300 229989004 N -023817199 003142600 -170864499

211

35 Structure TAP2 x y z N -125038016 006708711 -103472793 N 098191047 030544290 -113496149 C -123415029 039496627 034649506 C 143981278 -069842780 -024118215 C -040244716 -013646780 129148936 C 079877442 -092553216 093960589 H 161059022 038616386 -191021681 H -210653996 096405649 063256407 H 231400514 -126715899 -053131658 H -063691020 002892942 233540797 H 117717683 -167305398 162283337 N -026755595 -000521927 -173074698

36 Structure N1disTS2 x y z N -133099222 -033006421 -114672804 N 086660159 012573440 -116036201 C -135058701 -019655491 022691783 C 115805352 -020634329 020225337 C 083608705 080457932 127590036 C -011088291 -036102125 106437349 H 162620080 004583286 -180154109 H -233074379 -020847273 067531455 H 198558068 -089060324 034683317 H 140113795 102322769 217011189 H -013698517 -113811433 181993032 N -028204060 -021620022 -178218412

37 Structure N1disTS1

x y z N -130169976 019081797 -104405200 N 094327176 005109686 -123695779 C -121334004 030604666 032166755 C 123439634 -020356037 014254661 C 004350619 -000710853 108998549 C 064197320 -138673258 087150085 H 156055403 -038587660 -189167881 H -215111351 045885873 083115613

212

H 220896363 016127288 043982437 H 018502170 049485105 203912592 H 108914125 -205898929 158883250 N -030465758 003788886 -175479543


x y z N -126098287 -011335032 -109756756 N 096018976 019475992 -123826563 C -122259617 011114339 032740036 C 129074740 003986797 011038735 C 013311155 019243215 106727517 C -078314894 -100025153 124457669 H 167388237 002211608 -191340268 H -204474854 073682499 064738613 H 226751041 041516444 037965891 H 024753155 089269352 188646662 H -126557875 -135765290 214206529 N -025107780 -007207775 -177588069


x y z N -133402169 007713960 -110628259 N 089154190 -010330334 -131662345 C -122622192 -008966351 032074741 C 118516088 -070151305 -008374879 C -040124962 085500580 116130280 C 010227987 -054994255 095930445 H 154356277 -024694774 -205811739 H -215559125 -044409946 074359560 H 222735739 -062521011 020406279 H -066284949 139568162 205771351 H 008753270 -126916194 176845801 N -035202155 005420474 -182448196

Table C2 Imaginary frequencies for transition state 34-diazatricyclo[410027]hept-3-ene (DATCE)

Transition State Imaginary Frequencies

213

NdisTS 4033i CdisTS 4413i

NconTS1 3268i CconTS1 2356i NconTS2 7081i CconTS2 7747i

34-diazatricyclo[410027]heptane (DATCA) Transition State Imaginary Frequencies

NdisTSprime 4398i NdisTSPrime 3294i CdisTSprime 4620i CdisTSPrime 3643i

NconTS1prime 4227i NconTS1aPrime 3301i 4885i NconTS1bPrime 3052i 4606i CconTS1prime 2000i CconTS1Prime 3132i NconTS2prime 9098i NconTS2Prime 8724i CconTS2prime 7694i CconTS2Prime 6488i

Bold values are obtained at CCSD cc-pVDZCCSDcc-pVDZ level

345-triazatricyclo[410027] hept-3-ene (TATCE) Transition State Imaginary Frequencies

N1disTS1 4334i N1disTS2 3584i N3disTS2 4331i N3disTS1 3675i N3disTS2 4331i

Table C3 Calculated energies (Hartree) for each structure 34-diazatricyclo[410027]hept-3-ene (DATCE) Structure MCSCF ZPE MRMP2 PBEPBE-D3 DATCE -3017236903001 0109598 -3025916366963 -303154923914 DAP1 -3017852845205 0109653 -3026411678211 -303200469402 DAP2 -3017852845205 0109653 -3026411678211 -303200469402

214

NdisTS -3016377758015 0104762 -3025165611764 -303084220255 CdisTS -3016297400607 0104782 -3024971132792 -303070595746 NconTS1 -3016548840380 0105993 -3025306600574 -303096217765 CconTS1 -3016541621627 0105710 -3025275531027 -303092147066 NconTS2 -3016716130840 0104074 -3025408009928 -303102330698 CconTS2 -3016753745419 0104256 -3025406569291 -303071244272 NconInt -3017029804905 0107762 -3025669236398 -303129153587 CconInt -3017068060498 0107480 -3025684475418 -303120216093

34-diazatricyclo[410027]heptane(DATCA)

Structure MCSCF ZPE MRMP2 PBEPBE-D3 CCSD(T) DATCA -3029014682620 0136254 -3037919340517 -304358283994 -3042159678 DHDAP1 -3029699715730 0136015 -3038422778172 -304405386697 -3042646917 DHDAP2 -3029670840146 0135608 -3038400754340 -304405322061 -304264046 NdisTSprime -3028103316983 0130948 -3037036413285 -304264818910 NdisTSPrime -3028142990640 0131305 -3037083851669 -304271767750 CdisTSprime -3028084016120 0131051 -3036966586044 -304238467370 CdisTSPrime -3028088782722 0131338 -3036960771353 -304244315176 NconTS1prime -3028258076723 0131611 -3037186204701 -304283595573 NconTS1aPrime -3028318041029 0132247 -3037277955740 -304293443717 -3041477485 NconTS1bPrime -3028387148631 0133087 -3037336127380 -304307086151 -3041565024 CconTS1prime -3028342550094 0132362 -3037286637027 -304292573920 CconTS1Prime -3028266871968 0132188 -3037191381912 -304280327288 NconTS2prime -3028579700341 0130918 -3037471642280 -304294975744 NconTS2Prime -3028679603487 0131180 -3037567059467 -304299523558 CconTS2prime -3028647380936 0130944 -3037527406669 -304295483333 CconTS2Prime -3028535195921 0130730 -3037403459915 -304283278600 NconIntprime -3028946024660 0134561 -3037760106639 -304334280565 NconIntaPrime -3028392140314 0133210 -3037365206912 -304310168129 -3041625306 NconIntbPrime -3028979780559 0134985 -3037803967063 -304339154227 CconIntprime -3028978176085 0134888 -303779060056 -304335552596 CconIntPrime -3028890279445 0134556 -3037700277060 -304326755513

Bold values are obtained at CCSD(T)aug- cc-pVTZCCSDcc-pVDZ level

345-triazatricyclo[410027] hept-3-ene (TATCE)

Structure MCSCF ZPE MRMP2 PBEPBE-D3 TATCE -3177018181259 0097622 -3185983668777 -319184536393 TAP1 -3177612944617 0097650 -3186421572698 -319220672449 TAP2 -3177612944617 0097650 -3186421572698 -319220672449 N1disTS1 -3176174718748 0092727 -3185263960453 -319115340267 N1disTS2 -3176157311962 0092735 -3185229665412 -319112267448 N3disTS1 -3176175024882 0093715 -3185191920020 -319112849315

215

N3disTS2 -3176147485780 0093452 -3185162733931 -319109702140

Table C4 Natural orbital occupation numbers for active space orbitals 34-diazatricyclo[410027]hept-3-ene (DATCE)

MOs 11 22 23 24 25 26 27 28 29 30 NdisTS 1984 1979 1969 1968 1122 0879 0037 0022 0021 0018 CdisTS 1984 1979 1969 1969 1089 0912 0037 0022 0021 0018 NconTS1 1983 1980 1969 1951 1815 0195 0042 0027 0020 0017 CconTS1 1983 1980 1969 1957 1801 0207 0038 0026 0020 0017 NconTS2 1984 1979 1977 1911 1259 0741 0089 0022 0021 0017 CconTS2 1984 1979 1977 1911 1184 0817 0089 0023 0021 0017 NconInt 1984 1980 1975 1923 1880 0123 0075 0021 0020 0018 CconInt 1984 1981 1975 1924 1879 0124 0074 0021 0020 0018 DATCE 1984 1976 1972 1967 1961 0049 0029 0022 0021 0020 DAP1 1984 1981 1977 1936 1914 0090 0059 0022 0020 0016 DAP2 1984 1981 1977 1936 1914 0090 0059 0022 0020 0016

34-diazatricyclo[410027]heptane(DATCA) MOs 22 23 24 25 26 27 28 29 30 31

NdisTSrsquo 1983 1979 1968 1967 1170 0833 0038 0024 0021 0018 NdisTSrdquo 1984 1979 1969 1969 1231 0770 0037 0023 0021 0019 CdisTSrsquo 1984 1979 1968 1967 1059 0943 0037 0024 0021 0018 CdisTSrdquo 1983 1979 1968 1968 1004 0997 0038 0023 0021 0018 NconTS1rsquo 1983 1980 1970 1954 1774 0234 0041 0027 0020 0017 NconTS1ardquo 1984 1978 1969 1967 1786 0216 0037 0022 0021 0019 NconTS1rdquo 1983 1981 1970 1952 1886 0122 0039 0029 0021 0017 CconTS1rsquo 1984 1979 1969 1965 1766 0237 0036 0024 0020 0019 CconTS1rdquo 1983 1980 1969 1956 1760 0247 0040 0027 0020 0018 NconTS2rsquo 1983 1978 1976 1915 1241 0759 0086 0024 0021 0017 NconTS2rdquo 1983 1979 1976 1915 1164 0835 0085 0023 0021 0017 CconTS2rsquo 1983 1979 1976 1910 1171 0829 0090 0023 0021 0017 CconTS2rdquo 1983 1979 1976 1906 1215 0785 0094 0022 0021 0017 NconIntrsquo 1984 1981 1975 1923 1878 0124 0076 0021 0020 0018 NconIntardquo 1983 1981 1971 1961 1874 0130 0036 0026 0020 0018 NconIntbrdquo 1984 1980 1975 1930 1867 0135 0069 0022 0020 0018 CconIntrsquo 1984 1981 1975 1924 1877 0126 0074 0021 0020 0018 CconIntrdquo 1984 1981 1974 1920 1889 0114 0079 0022 0020 0018 DATCA 1984 1976 1972 1966 1960 0050 0028 0023 0021 0021 DHDAP1 1984 1981 1977 1939 1908 0094 0058 0023 0020 0015 DHDAP2 1984 1981 1978 1940 1911 0091 0058 0023 0020 0015

216

Figure C1 Intrinsic reaction coordinates for the four disrotatory channels for DATCA isomerization

217

APPENDIX D

218

Table D1 Cartesian coordinates for each structure (angstroms) 1 Structure benzvalene

x y z C -009361444 047055408 -010371051 C -015200381 -093900025 -033385876 C 095184845 -041491333 061543894 C -121816230 -032307038 060327506 C -081929094 -057226294 202780032 C 051743531 -062880653 203529787 H -005338311 134433365 -071904308 H -017388284 -157227170 -119538975 H 197589266 -040561116 029796284 H -223413920 -022717814 027443075 H -149503589 -067865151 285061836 H 117252612 -079153156 286556792

2 Structure benzene

x y z C -085505617 005631929 -053752303 C 043540058 -047491845 -062239611 C 109553993 -089561617 054381967 C -148410404 016636011 071348870 C -081795794 -025544071 186849093 C 046022141 -078167289 178441966 H -136642194 038006210 -142382693 H 092312366 -056240672 -157440042 H 208624983 -130372095 048048058 H -247475815 057401460 078048342 H -130065346 -017032450 282354045 H 096666014 -110388637 267439914

3 Structure disTS x y z

C -049969479 058574504 -058668292 C -009237672 -074989456 -045842883 C 103684449 -075878704 058275461 C -129300070 -015087587 053330708 C -082796496 -042341381 185065973 C 056331784 -064315730 185904157 H -101842010 096551085 -144943500 H -021508378 -155600154 -116254115

219

H 206526399 -074706024 028235289 H -233259010 -025569454 028742656 H -147755671 -048780558 269919682 H 117592144 -063192546 273840833

4 Structure disTSback


5 Structure conTS1a

x y z C -048189056 055429846 -049755874 C -013888088 -086964154 -044251925 C 099560082 -082889163 051910233 C -126933527 -029995376 047757158 C -079340148 -038347018 189495397 C 053385794 -063527673 188017821 H 008552479 145014083 -034385839 H -023843694 -156830096 -125148058 H 202433872 -088419771 022420867 H -229417372 -048871240 021709068 H -140814221 -021891335 275520730 H 118380952 -065634114 273140359

6 Structure conTS1b

x y z C -050297093 057183838 -051857948 C 011780674 -068796760 -050674665 C 117886078 -091360807 057008582 C -138284039 -021255155 045741639 C -079290003 -026335379 172978771 C 064550996 -057442611 176313233 H 004066788 141775155 -013330726

220

H -024384066 -149950397 -110985982 H 214899445 -133708191 041018009 H -238862038 -051306462 023680490 H -137164462 -027439317 263406634 H 117979980 -062746698 269191432

7 Structure conTS2 x y z

C -060312861 033196312 -060104370 C 040970480 -069692659 -072337109 C 127138186 -078242040 051838052 C -151094031 008356415 058478689 C -086735332 -036093181 168573689 C 058521593 -064758307 167377901 H -028780583 135953712 -070557755 H 010424759 -165644002 -111363649 H 230138612 -108459997 049898896 H -254118514 038453919 060916448 H -139321041 -047924933 261498356 H 107564771 -078701591 261932731

8 Structure conInta


9 Structure conIntb

x y z C -051464897 034783122 -048861307 C 031462818 -074718034 -062273878 C 129794645 -076641470 054574531 C -154038537 005896322 060560381 C -087581515 -037048936 170687735 C 059228200 -064087760 169694412

221

H -002741032 130146420 -033919087 H -017220303 -170378208 -075352222 H 233453703 -104218507 052124327 H -257708979 033494130 061710888 H -139146316 -049250481 264236450 H 107345223 -077493781 264900017

10 Structure benzvalyne x y z

C -009655527 046972793 -008906191 C -015227714 -094399583 -031827629 C 096095592 -041598082 063547862 C -123455715 -032644540 061718422 C -078297228 -057163441 201951647 C 046763608 -062262678 202995729 H -005597737 133870459 -071054584 H -017067322 -157307601 -118251884 H 198582458 -040685388 032961217 H -225004411 -023404928 029431415

11 Structure benzyne x y z

C -085433865 007954445 -050540119 C 045567364 -051211542 -056695950 C 111552680 -095593274 057378685 C -153788245 023954958 072220904 C -077983809 -023981614 178692305 C 035904256 -075357455 172803020 H -131895959 040563443 -141686261 H 092737263 -060839272 -152674186 H 209028578 -139730299 053802228 H -251223373 067773306 078508759

12 Structure disTSprime x y z

C -057148534 064626724 -053885663 C -007987246 -074889797 -042853338 C 103785706 -090788382 059108502 C -131887484 -019899753 047291785 C -075266618 -029607776 183234119 C 048937288 -057841164 184531891 H -100361979 109947145 -140774906 H -018274766 -144842732 -123862195 H 207025957 -100489724 033048084

222

H -233933306 -044720116 026152629 13 Structure conTS1aprime

x y z C -048499542 057807237 -044684583 C -018107219 -087599397 -042789406 C 095849288 -077209949 049913400 C -131527638 -025317946 050453913 C -077220047 -035460770 189710152 C 045264027 -060662371 186098838 H 006353579 149203587 -037687969 H -026955703 -155766630 -125254023 H 198156440 -073115003 019051071 H -234816957 -039383724 025838998

14 Structure conTS1bprime x y z

C -056745547 058684391 -048268569 C 015725785 -068826091 -049418423 C 115661573 -093949485 059854102 C -141760385 -023299107 047563148 C -070996094 -020483841 169769883 C 057978088 -046565640 174749911 H -010151576 150768197 -018310136 H -005886872 -142647159 -124150288 H 202429724 -155759370 050416756 H -242468691 -054710895 029699609

15 Structure conInta prime x y z

C -059775037 062431282 -046530423 C -012702130 -081251937 -042224678 C 099712479 -090821701 054368252 C -132997572 -027527353 048931655 C -075663209 -031396541 187261868 C 046679676 -059068650 185656762 H -005315014 151507330 -022183387 H -022591665 -146724463 -126617146 H 202726650 -101349378 027691770 H -233505273 -056371480 025802734

223

Table D2 Imaginary frequencies for transition state benzvalene

Transition State Imaginary Frequencies disTS 29492i

disTSback 33676i conTS1a 15927i conTS1b 72843i conTS2 84986i

benzvalyne

Transition State Imaginary Frequencies disTSrsquo 22638i

conTS1arsquo 31699i conTS1brsquo 107186i

Table D3 Calculated energies (Hartree) for each structure benzvalene Structure MCSCF ZPE MRMP2 benzvalene -2307610277333 0101768 -2316034371904 benzene -2309012367588 0104108 -2317302258617 disTS -2307166847405 0098434 -2315674694378 disTSback -2307094137023 0097831 -2315521850547 conTS1a -2307110932530 0098057 -2315571473528 conInta -2307113331421 0098003 -2315540633982 conTS1b -2306955856068 0097540 -2315479338186 conIntb -2307399238638 0100427 -2315769472948 conTS2 -2307328819966 0097628 -2315666894649

benzvalyne Structure MCSCF ZPE MRMP2 benzvalyne -2294824455493 0077037 -2302567437929 benzyne -2296520074000 0078155 -2304154135000 disTSprime -2294355307572 0071925 -2302152332228 conTS1aprime -2294373847249 0072905 -2302182070091 conIntaprime -2294384786149 0073032 -2302163170536 conTS1bprime -2294206545733 0070416 -2302114283808

224

Table D4 Natural orbital occupation numbers for active space orbitals benzvalene

MOs 17 18 19 20 21 22 23 24 25 26 disTS 1978 1973 1962 1926 1711 0295 0073 0036 0024 0022 disTSback 1980 1979 1967 1913 1039 0962 0087 0033 0021 0020 conTS1a 1982 1977 1967 1914 1618 0384 0084 0033 0022 0019 conTS1b 1978 1975 1936 1915 1679 0330 0078 0066 0022 0022 conTS2 1978 1978 1932 1885 1309 0697 0115 0065 0023 0019 conInta 1981 1979 1968 1908 1248 0753 0091 0032 0021 0019 conIntb 1977 1975 1931 1889 1756 0252 0112 0065 0023 0020 Benzvalene 1979 1975 1971 1964 1912 0088 0038 0029 0023 0021 Benzene 1982 1981 1961 1911 1908 0093 0090 0036 0019 0017

benzyne

MOs 15 16 17 18 19 20 21 21 23 24 25 26 disTSprime 1981 1969 1962 1908 1697 1236 0767 0303 0091 0041 0024 0020

conTS1aprime 1981 1970 1965 1911 1763 1710 0290 0241 0086 0039 0023 0021 conTS1bprime 1981 1970 1925 1891 1689 1426 0584 0319 0089 0081 0025 0020 conIntaprime 1981 1970 1965 1911 1751 1477 0524 0252 0087 0039 0023 0020

Benzvalyne 1978 1974 1970 1962 1901 1735 0268 0095 0040 0030 0024 0021 Benzyne 1982 1977 1958 1912 1905 1835 0166 0098 0087 0039 0022 0017

225

226

VITA

WEIWEI YANG

Education PhD The University of Mississippi USA 082015-082019 MS in Chemical Engineering Ocean University of China China 092012-072015 BS in Pharmaceutical Engineering Northwest University China 092008-072012

Publication and Patent bull Yang W Davis S R The ab initio Study of Thermal Isomerization of Benzvalene to

Benzene and Benzvalyne to Benzyne Manuscript preparation bull Poland K N Yang W Mitchell E C Dam A A Davis S R Heterocyclic Isomers of

Forbidden and Allowed Pathways Forged from a Pericyclic Reactant Manuscript preparation bull Yang W Poland K N Davis S R Isomerization barriers and resonance stabilization for

the conrotatory and disrotatory isomerizations of nitrogen containing tricyclo moieties Physical Chemistry Chemical Physics2018 20 26608

bull Liyanage N P Yang W Guertin S Sinha Roy S Carpenter C A Schmehl R H Delcamp J H Jurss J W Photochemical CO2 reduction with mononuclear and dinuclear rhenium catalysts bearing a pendant anthracene Chromophore Chemical Communication 2019 55 993-996

bull Yang W Sinha Roy S Pitts W C Nelson R Fronczek F R Jurss J W Electrocatalytic CO2 Reduction with cis and trans Conformers of a Rigid Dinuclear Rhenium Complex Comparing the Mon-ometallic and Cooperative Bimetallic Pathways Inorganic Chemistry 2018 57 (15)9564ndash9575

bull Zhang J Yang W Vo AQ Feng X Ye X Kim DW et al Hydroxypropyl methylcellulose-based controlled release dosage by melt extrusion and 3D printing Structure and drug release correlation Carbohydrate Polymers 2017 177 49ndash57

bull Yang W Li C Wang L Sun S Yan X Solvothermal fabrication of activated semi-coke supported TiO2-rGO nanocomposite photocatalysts and application for NO removal under visible light Applied Surface Science 2015 353 307-316

bull Li C Yang W Wang L A Preparation Method of Carbon-based Photocatalyst for NO Removal Pub NO CN104307542B

227

Honors and Awards bull Outstanding Chemistry Graduate Student for the American Chemist Society The University

of Mississippi 042016 bull Third Prize of the 2014 ShanDong Province College Students Entrepreneurship Competition

(Leader) 062014 bull First Prize of the 9th OUC Challenge Cup Entrepreneurship Competition (Leader) 052014 bull Outstanding Student (ie First-class Scholarship) OUC 112013 bull Third Prize of the 9th National Post-graduate Mathematical Contest in Modeling China

122012 bull First Prize of the 3rd Sinology Knowledge Competition OUC 112012 bull Second Prize of the ldquoMitsui cuprdquo Chemical Engineering Design Competition NWU 052011 bull Outstanding Student (ie First-class Scholarship ) NWU 122010 bull National Encouragement Scholarship NWU 052010 bull Second-class Scholarship NWU 122009

Electro- and photocatalytic carbon dioxide reduction and thermal isomerization of highly strained tricyclocompounds

Recommended Citation

ABSTRACT


ACKNOWLEDGEMENTS

LIST OF TABLES

LIST OF FIGURES

INTRODUCTION

CHAPTER I ELECTROCATALYTIC CO2 REDUCTION WITH CIS AND TRanS CONFORMERS OF A RIGID DINUCLEAR RHENIUM COMPLEX

11 Introduction












15 Conclusion

CHAPTER II PHOTOCHEMICAL CO2 REDUCTION WITH MONONUCLEAR AND DINUCLEAR RHENIUM CATALYSTS BEARING A PENDANT ANTHRACENE CHROMOPHORE

21 Introduction









232 Photocatalysis

233 Quantum yield

24 Conclusion

CHAPTER III ISOMERIZATION BARRIERS AND RESONANCE STABILIZATION FOR THE CONROTATORY AND DISROTATORY ISOMERIZATIONS OF NITROGEN CONTAINING TRYCYCLO MOIETIES

31 Introduction













35 Conclusion

CHAPTER IV THE AB INITIO STUDY OF THERMAL ISOMERIZATION OF BENZVALENE TO BENZENE AND BENZVALYNE TO BENZYNE

41 Introduction



431 Benzvalene



432 Benzvalyne



44 Conclusion

CONCLUSION

BIBLIOGRAPHY

List of APPENDICES

APPENDIX A

APPENDIX B

APPENDIX C

APPENDIX D

VITA

ELECTRO- AND PHOTOCATALYTIC CARBON DIOXIDE REDUCTION AND THERMAL

ISOMERIZATION OF HIGHLY STRAINED TRICYCLOCOMPOUNDS

A Dissertation

presented in partial fulfillment of requirements for the degree of Doctor of Philosophy

in the Department of Chemistry and Biochemistry The University of Mississippi

by

WEIWEI YANG

August 2019


ii

ABSTRACT



















iii










iv


CO2 carbon dioxide

CO carbon monoxide





DAP 3H-12-diazepine












v






TS transition state







ν scan rate







vi







T temperature



TON turnover number



MeOH methanol

PhOH phenol


PS photosensitizer


TEA triethylamine

φ quantum yield

vii








viii

ACKNOWLEDGEMENTS
















ix










x




LIST OF TABLES xiv

LIST OF FIGURES xv

INTRODUCTION 1



11 Introduction 7










xi



15 Conclusion 38



CHROMOPHORE 40

21 Introduction 40











24 Conclusion 55

xii




31 Introduction 57







35 Conclusion 93



41 Introduction 96



431 Benzvalene 99

432 Benzvalyne 106

44 Conclusion 111

xiii

CONCLUSION 113

BIBLIOGRAPHY 115

APPENDIX A 139

APPENDIX B 187

APPENDIX C 195

APPENDIX D 217

VITA 226

xiv

LIST OF TABLES


pH 7 vs NHE) 2















xv

LIST OF FIGURES











blue line 22








xvi










solutions 34





38



(2) 41


xvii












example above 55








xviii



66







74









xix



isomerization 85










isomerizations 92



100



xx








1

INTRODUCTION



















2

















3






















4












5











6


















conclusion44-46

7

CHAPTER I



11 Introduction














8









Cl ClO

O 1 Zn NH4OH (20) 80 oC 5 h

2 HCl iPrOH

Cl Cl

2 B B

Pd2(dba)3 + 4Xphos

dioxane 90 oC 2 d

B BO O O O

O

O O

O

N NBr


NN

NN

NN

NN

Re ReClOC

COOCOC CO

Cl CO

cis-Re2Cl2 1

Re(CO)5Cl

toluene ∆1 d

1a88

1b88

86

trans-Re2Cl2

N

N

N

N

Re

Re

OC

OC

OC

OCCl

Cl

OC

CO

+

41 20

9





















10





















11


electrode















CIF file




12




















13
















14901 13799 13785 13701 13155 12914 12906 12738 12691 12550 12492 12384






14








2H) 13C NMR (126 MHz DMF-d7) δ 19947 19509 19507 16187 15822 15757 15410

14111 14077 13341 13190 13157 13142 13102 12877 12871 12848 12832 12682








19936 19883 19514 19484 19195 19096 16248 16245 15790 15783 15760 15706

15420 15409 14180 14136 14112 14091 14059 13959 13331 13322 13191 13160

13150 13092 13057 13037 12928 12881 12861 12851 12667 12612 12601 12590



15












2H) 13C NMR (126 MHz DMSO-d6) δ 15847 15582 15549 14984 13887 13832 13789

13216 13198 13149 12973 12941 12906 12826 12778 12713 12643 12626 12569


3331







16




288 N 422


















17




1893 cm-1 in DMF16







days

74757677787980818283848586878889909192f1 (ppm)

199

195

416

108

201

220

192

192

200

096

200

7727374757677787980818283848586878889909192f1 (ppm)

088

098

099

106

198

328

099

088

300

107

088

092

090

095

084

092

102

A

B

18














19





















20





Figure A9)7980








N

NRe

OC

OCCl

CO

21



cis-Re2Cl2 -177 -187 -234 -265

KC = 50

trans-Re2Cl2 -178 -188 -240 -267

KC = 50

Re(bpy)(CO)3Cl -180 -225 - - D = 540 x 10-6 cm2 s-1

anthryl-Re -182 -229 -254 - D = 548 x 10-6 cm2 s-1











22




119894119894119888119888119888119888119888119888 = 119899119899119888119888119888119888119888119888119865119865119865119865[119888119888119888119888119888119888](119863119863119896119896119888119888119888119888119888119888[119878119878]119910119910)12 (1)

B

D

23













A B

24






Rate = minus[CO2]







B

25




















26








substrate5859

119879119879119879119879119865119865 = 119896119896119888119888119888119888119888119888[1198621198621198791198792] = 1198651198651198651198651198991198991199011199013

11987711987711987711987704463119899119899119888119888119888119888119888119888

21198941198941198881198881198881198881198881198881198941198941199011199012 (2)










119894119894119894119894119901119901

=224

119877119877119877119877119865119865119865119865119899119899119901119901

32119896119896119888119888119888119888119888119888[1198621198621198621198622]

1+119890119890119890119890119890119890 119865119865119877119877119877119877(119864119864minus1198641198641198881198881198881198881198881198882) (3)

27






















28












29





into account100

C

A B

D

30

119864119864 = 1198641198641198621198621198621198622119862119862119862119862(119863119863119863119863119865119865)0 minus 00592 ∙ 119901119901119901119901119888119888 (4)









TOF (s-1) eq 3

Ecat2

(120578120578)a Ecat2

(120578120578)b

cis-Re2Cl2 353 110 -229 (156)

-209 (092)

trans-Re2Cl2 229 44 -234 (161)

-195 (078)

Re(bpy)(CO)3Cl 111 15 -222 (149)

-204 (087)

anthryl-Re 192 41 -226 (153)

-218 (101)


0







31





















32





















33













B

cis-Re2Cl2

34











D

35






















36














+endash

-


37










38


15 Conclusion







NN

NN

Re ReOC

COOCOC CO

O CO

O

NN

NN

Re ReClOC

COOCOC CO

Cl CO

NN

NN

Re ReOC

COOCOC CO

CO

+2e -2Cl__

NN

NN

Re ReOC

COOCOC CO

O CO

HO

NN

NN

Re ReOCOC

COOCOC CO

CO

+H+

H2O

+e_

CO

+

+CO2

+H+ e_

39



















bond formation

40

CHAPTER II



21 Introduction










improved





41







Re2Cl2








N

N

N

N

Re

Re

OC

OC

OC

OCCl

OC

CO

HOO

NN

NN

Re Re0OC

COOCOC CO

Cl CON

NN

N

Re ReOC

COOCOC CO

O CO

O

N

N

N

N

Re

Re

OC

OC

OC

OCCl

CO

OC

CO

42


















such as BIH

43













44












and





NN

NN

Re ReClOC

COOCOC CO

Cl CON

N

N

N

Re

Re

OC

OC

OC

OCCl

Cl

OC

CO

N

NRe

OC

OCCl

CO

N

NRe

Cl

CO

CO

CO

45





















46






















47


















(1a)



48






















49





















50


232 Photocatalysis








51


















infra)

52
















53






















54

233 Quantum yield













55


24 Conclusion







56










57

CHAPTER III




31 Introduction







energy

58










59
















60













61









structure








62






















63

















64


















65


66








in Figure 25


67
















68
















transition state






69







energetics










70















71






bonded atoms









72






















73






















74












75













76




77



446 02

433 17

489 19









78









dihedral angle







79






















80








portion of the PES



81

















82






















83
















DHDAP products

84









85










86

















87














88
















89














transition state

90










activation barrier

91













92





93

35 Conclusion





















94






















95















the MRMP2 results

96

CHAPTER IV



41 Introduction















97






















98



















energy release

99


431 Benzvalene













100













101












102



















103














104












105





106

432 Benzvalyne







in Figure 48


107









108














109






















110








111




44 Conclusion
















112






kcal mol-1 barrier

113


















114




lone pair electrons









115

BIBLIOGRAPHY

116






305 (5682) 362ndash366






38 (1) 89ndash99





1399



117






7 (1) 70ndash88








536ndash538



1984 328ndash330




118





3387






2966ndash2974



Chem 2010 49 (20) 9283ndash9289








119








(5) 2966ndash2976



13993ndash13996




3214ndash3226



354ndash363




120




Soc 2015 137 (42) 13679ndash13690




3746ndash3754




10725







Am Chem Soc 2016 138 (6) 1938ndash1946



121






487ndash495






(10) 2931ndash2932



1988 110 (6) 1666ndash1671


Am Chem Soc 1995 117 (13) 3835ndash3847





122

Chem A 2009 113 (30) 8724ndash8730



Chem A 1999 103 (51) 11253ndash11256


















123





2003 125 (39) 11976ndash11987






5180ndash5186



7374ndash7376








124



6030



2012 41 (16) 5026ndash5037







14598ndash14607




138 (26) 8184ndash8193





125




Inorg Chem 2017 56 (7) 4176ndash4185



4593ndash4597



Madison WI 2000











2015 71 9ndash18

126




263ndash272




Trans 2012 41 (18) 5526ndash5541








2011 40 (10) 2225ndash2233






127


















1964 36 (4) 706ndash723



9983ndash10002

128



















(27) 11235ndash11242



129



8309ndash8318







2012 109 (39) 15646ndash15650



9329





463ndash469




130







(10) 2956ndash2962















131





7708






2012 41 (16) 5026ndash5037




14413ndash14424







132

1997 119 (45) 11012ndash11022



2001 105 (35) 8154ndash8161











2017 7 (1) 154ndash160




2013 135 (40) 15018ndash15025



133




2014 136 (48) 16768ndash16771








44 6311ndash6318



849ndash858



11806




134

135






Chem 2003 68 (23) 9081ndash9087







1358ndash1371




380




135


B01 2016





Chem A 2017 121 (46) 8899ndash8911




Soc 1975 97 (10) 2932ndash2933





1993 412 412ndash414



Soc 1998 120 (23) 5741ndash5750



136

(5) 1202ndash1204












Chem Phys 2012 14 (27) 9722ndash9728







1997 2 2761ndash2764


137









138

LIST OF APPENDICES

139

APPENDIX A

140


141

NN

NN

Re ReClOC

COOCOC CO

Cl CO

cis-Re2Cl2(CS

symmetric Cl-in)


1Cl-in 1Cl-out)

N

N

N

N

Re

Re

OC

OC

OC

OCCl

Cl

OC

CO

NN

NN

Re ReOCCl

COOCOC CO

CO Cl

cis 2


NN

NN

Re ReClCl

COOCOC CO

CO CO

cis 3

(asymmetric C1)

NN

NN

Re ReOCOC

COOCOC CO

Cl Cl

trans 2


N

N

N

N

Re

Re

OC

OC

OC

OCCl

CO

Cl

CO

N

N

N

N

Re

Re

OC

OC

OC

OCOC

Cl

OC

Cl

N

N

N

N

Re

Re

OC

OC

OC

OCOC

CO

Cl

Cl

cis 4

(asymmetric C1)

enantiomers

same

trans 3


1 2

4

6

7

5

3

142




714

717

718

724

725

727

733

743

744

748

750

752

753

755

760

762

764

765

769

771

773

774

774

776

783

788

790

791

800

802

803

834

835

837

839

840

842

856

858

860

862

868

869

872

874

876

878

888

898

899

900

902

903

904

7273747576777879808182838485868788899091f1 (ppm)

143



144



145







intersecting waves

119894119894119890119890 = 04463119899119899119865119865119865119865119862119862 119899119899119865119865νD119877119877119877119877

12

Equation 1





146





-15 -18 -21 -24 -27-40

-20

0

20

40

60

80

Cur

rent

micro

A

Potential V vs Fc+0


147



A B

B

148


149


150


151

A

B

152







153


C D

154



A B

B

155


156



NN

NN

Re ReOC

COOCOC CO

O CO

O

NN

NN

Re ReClOC

COOCOC CO

Cl CO

NN

NN

Re ReOC

COOCOC CO

CO

+2e -2Cl__

NN

NN

Re ReOC

COOCOC CO

O CO

HO

NN

NN

Re ReOCOC

COOCOC CO

CO

+H+

H2O

+e_

CO

+

+CO2

+H+ e_

157


158


159


160



161


162


163



164


165


166


167


168


169


170


171


172


173



174


175



176


177




178




179


6971

7375

7779

8183

8587

8991

9395

9799

101f1 (ppm

)

201

214411395206

206

206

200

104

105

732732732733733733733734734756756757758759759767767768768768769769770770771774775775775775776776776777777782782782783784784797797797798798799827828861861861861861862862862862883980

NN

NN1

180

110115

120125

130135

140145

150155

160165

f1 (ppm)

11861

11996

1236112384124921255012691127381290612914

13155

137011378513798

14901

1545215489

15760

NN

NN1

181

7374

7576

7778

7980

8182

8384

8586

8788

8990

9192

93f1 (ppm

)

199

195

416

108

201

220192

192

200

096

200

753754760762

773773774776783788790791

834835837838840

868869876878

887

903904

NN

NN

ReRe

ClO

C

COO

CO

CCO

ClCO

cis -Re2 Cl2

182

DM

F

120125

130135

140145

150155

160165

170175

180185

190195

200205

f1 (ppm)

12404124941259312610126821283212848128711287713102131421315713190133411407714111

15410

1575715822

16187

1950719509

19947

NN

NN

ReRe

ClO

C

COO

CO

CCO

ClCO

cis -Re2 Cl2

183

7172

7374

7576

7778

7980

8182

8384

8586

8788

8990

9192

93f1 (ppm

)

088

098099106

198

328

099

088

300

107

088092

090095

084

092102

733743744748750752753755764765769771772774775781783784800802803

834835837840842843856858860862872873876878

887

897899900901

trans-Re2 Cl2

NN

N N

Re Re

OC

OC

OC

OC

Cl

Cl

OC

CO

184

105110

115120

125130

135140

145150

155160

165170

175180

185190

195200

205f1 (ppm

)

12392124391244212590126011261212667128511286112881129281303713057130921315013160131911332213331139591405914091141121413614180

154091542015706157601578315790162451624816315 DMF-d7

19096191951948419514

1988319936

DM

F

trans-Re2 Cl2

NN

N N

Re Re

OC

OC

OC

OC

Cl

Cl

OC

CO

185

6970

7172

7374

7576

7778

7980

8182

8384

8586

8788

8990

9192

9394

f1 (ppm)

202

112

108

102

103110108

107109104

098

097

100101096

747748749750753755756764766766767772774784786791792793793794795799801812814817818820823824840842

851853

872875876884

NN

2

186

114116

118120

122124

126128

130132

134136

138140

142144

146148

150152

154156

158160

162164

f1 (ppm)

1195712107124791248612550125691262612643127131277812826129061294112973131491319813216

137891383213887

14984

1554915582

15847

NN

2

187

APPENDIX B

188


(log ε)

120582120582119898119898119888119888119890119890119890119890119898119898 119899119899119899119899 λ1 λ2

ℎ120596120596 119888119888119899119899minus1

λ2



anthryl-Re 252 (480) 296 (415 366 (398)

570 688 764 1440

420 6 23

430 (1)

cis-Re2Cl2 258 (485) 296 (442) 380 (412)

592 700 776 1400

210 15 65

440 (1) 520 (1)

trans-Re2Cl2 258 (470) 296 (427) 376 (395)

598 698 772 1370

200 15 90

440 (1) 490 (095)


355 375

375 670 ---

6 3300 410 440


189


190

191

192





193





194


195

APPENDIX C

196



2 Structure DAP1


3 Structure DAP2

x y z N -116779101 -064002001 -108525395 C 068300301 075432998 -125431597 C -147904301 -010512900 018798700 C 148783505 028317201 -007852600

197

C 086488998 -000468100 110520506 C -060514897 007661000 123283005 H 006928100 161709297 -097713298 H 132201004 103113604 -208814597 H -254451108 -006943700 036536899 H 255957389 017099699 -017685100 H 144391096 -028888100 197464800 H -102901101 024935301 221440911 N -019210300 -032655400 -173923600

4 Structure NdisTS


5 Structure CdisTS


198

H -162471807 100128031 -085891795


7 Structure CconTS1


8 Structure NconInt

x y z N -117254436 -012935539 -103004634 C 114911330 052507800 -132641387 C -120073497 -078021890 027967709

199

C 134310114 -015687630 -002968836 C 069569921 037333986 107144785 C -048748320 -048004261 141496575 H 133888507 159884501 -131786120 H 169165754 009332362 -216674495 H -209250116 -139012527 032793716 H 135121119 -123951328 -009737577 H 064599955 144558704 123436141 H -081668174 -079587555 239674282 N -030165136 040838382 -168327153

9 Structure CconInt



x y z N -122473168 -045778599 -113910139 C 094505334 056573945 -136906683 C -131874728 -057033855 028926978 C 141338336 001856516 -006715097 C 073123562 049870428 117475450 C -057058573 -001180191 135865033 H 081215769 165091348 -134124863 H 163488150 034631550 -218331766 H -227999783 -100280988 053255856 H 165092111 -104281521 -007590441 H 117330158 121783650 185320687

200

H -107045138 005085879 231917119 N -035554022 002986831 -183606148



12 Structure DATCA


13 Structure DHDAP1

x y z

201


14 Structure DHDAP2



x y z N -142339540 -014606592 -116566598 C 093296069 025221679 -126147401 C -140808904 -032721406 022840041

202

C 119161737 -016610871 018556029 C 084130841 081545776 126951730 C -012877002 -034134027 101129293 H 080472010 133444512 -132227707 H 179706573 000164181 -187867403 H -235516500 -018690881 072857887 H 200624251 -086340731 035096633 H 139543521 092786473 219372249 H -011925846 -106822538 181810999 N -023407100 -035943642 -187034750 H -186182213 070168203 -147589076 H -010957908 -135344136 -195132947




x y z N -139562595 013293861 -109109366 C 099973285 019917566 -139172935 C -128806067 019103202 034260291 C 129041827 019030157 008237755 C 011506672 024624294 103696835 C -077405405 -098817056 111280930

203

H 101604879 123224723 -176587749 H 177840137 -033207700 -194385386 H -209643722 075877380 078947771 H 225147820 055132854 042733517 H 023269734 084052205 193693876 H -118028319 -148607981 198114049 N -027926472 -037997854 -177376115 H -158354163 104699314 -146162188 H -027862626 -137567961 -164485288




x y z N -143094933 000844477 -105635679 C 098796737 019592127 -131666112 C -139533913 -048966303 027399421 C 113849020 -002605952 017835093 C 054325736 089400637 112329757 C -024462490 -043452144 110718977 H 113207793 126165700 -151517606 H 175230050 -034002155 -188157892 H -231300664 -094758868 062348062

204

H 186804652 -073859274 054489440 H 004017371 175133789 067512351 H -011543095 -115248680 190509605 N -030366421 -020636971 -186336851 H -177593493 094211507 -117049420 H -029553342 -118461883 -208670139




x y z N -137007999 021642189 -103387082 C 101358879 009395494 -136566508 C -117764771 048460183 031954116 C 124384856 -023482305 009737201

C -016166560 -002143468 113447988 C 062831956 -134321129 076988173 H 116087043 116113365 -154630864 H 172647870 -044072470 -199733388 H -194308221 112372172 074224061 H 196049356 037644607 063625616 H -003499719 042012647 211345911 H 005090978 -197989404 009782664

205

N -032054877 -028873754 -181068313 H -182399678 097171456 -150863016 H -039848125 -128864574 -180960560





206





207





x y z N -150680757 056806660 -130433857

208

C 090254611 -013684431 -134248567 C -133901668 018480022 005263753 C 122509563 -068525136 007712884 C -045107952 076213592 092525667 C 066651374 -021551019 124015796 H 128556395 088743246 -137062228 H 151083350 -069635767 -205396152 H -155124116 -086979580 018505041 H 208378029 -134905469 012883927 H -018387491 181044579 081894964 H 104705095 -047549337 222000599 N -043426350 -010652254 -197062349 H -136226058 155375171 -143762600 H -075494838 -103908885 -215765285




x y z N -095442176 070564193 -090830022 C 109275067 -032066563 -159886014 C -129964244 034616992 040946886 C 153150833 -012862645 -017070051

209

C -051763374 -047516546 124236357 C 080180967 -090327680 089841759 H 152177787 045718437 -223145628 H 141152573 -128543031 -200184107 H -224236107 073953104 076580024 H 177199173 089397639 010826312 H -098024762 -082737643 215669823 H 125232351 -175105810 139811301 N -036664572 -028272822 -171884358 H -172617841 110976660 -139820719 H -073830664 -118157279 -145777547




x y z N -137026465 073302871 -128783345 C 087258899 -026980808 -142273438 C -154870033 032182592 005344129 C 116283774 -062507212 003527457 C -060129660 069691128 116412342 C 062601334 -001556111 119647968 H 141744506 066357487 -160980988

210

H 135420501 -101914442 -205298281 H -188953984 -070950902 010131884 H 209415388 -116732562 016407259 H -087284940 139373589 194623566 H 121124625 -005525590 210910273 N -046208549 -009558035 -198351347 H -105760002 168298090 -136993039 H -091536391 -098043090 -211986423

33 Structure TATCE


34 Structure TAP1


211




x y z N -130169976 019081797 -104405200 N 094327176 005109686 -123695779 C -121334004 030604666 032166755 C 123439634 -020356037 014254661 C 004350619 -000710853 108998549 C 064197320 -138673258 087150085 H 156055403 -038587660 -189167881 H -215111351 045885873 083115613

212

H 220896363 016127288 043982437 H 018502170 049485105 203912592 H 108914125 -205898929 158883250 N -030465758 003788886 -175479543







213










214







215

N3disTS2 -3176147485780 0093452 -3185162733931 -319109702140





216


217

APPENDIX D

218



2 Structure benzene



C -049969479 058574504 -058668292 C -009237672 -074989456 -045842883 C 103684449 -075878704 058275461 C -129300070 -015087587 053330708 C -082796496 -042341381 185065973 C 056331784 -064315730 185904157 H -101842010 096551085 -144943500 H -021508378 -155600154 -116254115

219

H 206526399 -074706024 028235289 H -233259010 -025569454 028742656 H -147755671 -048780558 269919682 H 117592144 -063192546 273840833



5 Structure conTS1a


6 Structure conTS1b

x y z C -050297093 057183838 -051857948 C 011780674 -068796760 -050674665 C 117886078 -091360807 057008582 C -138284039 -021255155 045741639 C -079290003 -026335379 172978771 C 064550996 -057442611 176313233 H 004066788 141775155 -013330726

220

H -024384066 -149950397 -110985982 H 214899445 -133708191 041018009 H -238862038 -051306462 023680490 H -137164462 -027439317 263406634 H 117979980 -062746698 269191432


C -060312861 033196312 -060104370 C 040970480 -069692659 -072337109 C 127138186 -078242040 051838052 C -151094031 008356415 058478689 C -086735332 -036093181 168573689 C 058521593 -064758307 167377901 H -028780583 135953712 -070557755 H 010424759 -165644002 -111363649 H 230138612 -108459997 049898896 H -254118514 038453919 060916448 H -139321041 -047924933 261498356 H 107564771 -078701591 261932731

8 Structure conInta


9 Structure conIntb

x y z C -051464897 034783122 -048861307 C 031462818 -074718034 -062273878 C 129794645 -076641470 054574531 C -154038537 005896322 060560381 C -087581515 -037048936 170687735 C 059228200 -064087760 169694412

221

H -002741032 130146420 -033919087 H -017220303 -170378208 -075352222 H 233453703 -104218507 052124327 H -257708979 033494130 061710888 H -139146316 -049250481 264236450 H 107345223 -077493781 264900017


C -009655527 046972793 -008906191 C -015227714 -094399583 -031827629 C 096095592 -041598082 063547862 C -123455715 -032644540 061718422 C -078297228 -057163441 201951647 C 046763608 -062262678 202995729 H -005597737 133870459 -071054584 H -017067322 -157307601 -118251884 H 198582458 -040685388 032961217 H -225004411 -023404928 029431415


C -085433865 007954445 -050540119 C 045567364 -051211542 -056695950 C 111552680 -095593274 057378685 C -153788245 023954958 072220904 C -077983809 -023981614 178692305 C 035904256 -075357455 172803020 H -131895959 040563443 -141686261 H 092737263 -060839272 -152674186 H 209028578 -139730299 053802228 H -251223373 067773306 078508759


C -057148534 064626724 -053885663 C -007987246 -074889797 -042853338 C 103785706 -090788382 059108502 C -131887484 -019899753 047291785 C -075266618 -029607776 183234119 C 048937288 -057841164 184531891 H -100361979 109947145 -140774906 H -018274766 -144842732 -123862195 H 207025957 -100489724 033048084

222


x y z C -048499542 057807237 -044684583 C -018107219 -087599397 -042789406 C 095849288 -077209949 049913400 C -131527638 -025317946 050453913 C -077220047 -035460770 189710152 C 045264027 -060662371 186098838 H 006353579 149203587 -037687969 H -026955703 -155766630 -125254023 H 198156440 -073115003 019051071 H -234816957 -039383724 025838998


C -056745547 058684391 -048268569 C 015725785 -068826091 -049418423 C 115661573 -093949485 059854102 C -141760385 -023299107 047563148 C -070996094 -020483841 169769883 C 057978088 -046565640 174749911 H -010151576 150768197 -018310136 H -005886872 -142647159 -124150288 H 202429724 -155759370 050416756 H -242468691 -054710895 029699609


C -059775037 062431282 -046530423 C -012702130 -081251937 -042224678 C 099712479 -090821701 054368252 C -132997572 -027527353 048931655 C -075663209 -031396541 187261868 C 046679676 -059068650 185656762 H -005315014 151507330 -022183387 H -022591665 -146724463 -126617146 H 202726650 -101349378 027691770 H -233505273 -056371480 025802734

223




benzvalyne





224



benzyne

MOs 15 16 17 18 19 20 21 21 23 24 25 26 disTSprime 1981 1969 1962 1908 1697 1236 0767 0303 0091 0041 0024 0020



225

226

VITA

WEIWEI YANG











227







ABSTRACT


ACKNOWLEDGEMENTS

LIST OF TABLES

LIST OF FIGURES

INTRODUCTION


11 Introduction












15 Conclusion


21 Introduction









232 Photocatalysis

233 Quantum yield

24 Conclusion


31 Introduction













35 Conclusion


41 Introduction



431 Benzvalene



432 Benzvalyne



44 Conclusion

CONCLUSION

BIBLIOGRAPHY

List of APPENDICES

APPENDIX A

APPENDIX B

APPENDIX C

APPENDIX D

VITA


ii

ABSTRACT



















iii










iv


CO2 carbon dioxide

CO carbon monoxide





DAP 3H-12-diazepine












v






TS transition state







ν scan rate







vi







T temperature



TON turnover number



MeOH methanol

PhOH phenol


PS photosensitizer


TEA triethylamine

φ quantum yield

vii








viii

ACKNOWLEDGEMENTS
















ix










x




LIST OF TABLES xiv

LIST OF FIGURES xv

INTRODUCTION 1



11 Introduction 7










xi



15 Conclusion 38



CHROMOPHORE 40

21 Introduction 40











24 Conclusion 55

xii




31 Introduction 57







35 Conclusion 93



41 Introduction 96



431 Benzvalene 99

432 Benzvalyne 106

44 Conclusion 111

xiii

CONCLUSION 113

BIBLIOGRAPHY 115

APPENDIX A 139

APPENDIX B 187

APPENDIX C 195

APPENDIX D 217

VITA 226

xiv

LIST OF TABLES


pH 7 vs NHE) 2















xv

LIST OF FIGURES











blue line 22








xvi










solutions 34





38



(2) 41


xvii












example above 55








xviii



66







74









xix



isomerization 85










isomerizations 92



100



xx








1

INTRODUCTION



















2

















3






















4












5











6


















conclusion44-46

7

CHAPTER I



11 Introduction














8









Cl ClO

O 1 Zn NH4OH (20) 80 oC 5 h

2 HCl iPrOH

Cl Cl

2 B B

Pd2(dba)3 + 4Xphos

dioxane 90 oC 2 d

B BO O O O

O

O O

O

N NBr


NN

NN

NN

NN

Re ReClOC

COOCOC CO

Cl CO

cis-Re2Cl2 1

Re(CO)5Cl

toluene ∆1 d

1a88

1b88

86

trans-Re2Cl2

N

N

N

N

Re

Re

OC

OC

OC

OCCl

Cl

OC

CO

+

41 20

9





















10





















11


electrode















CIF file




12




















13
















14901 13799 13785 13701 13155 12914 12906 12738 12691 12550 12492 12384






14








2H) 13C NMR (126 MHz DMF-d7) δ 19947 19509 19507 16187 15822 15757 15410

14111 14077 13341 13190 13157 13142 13102 12877 12871 12848 12832 12682








19936 19883 19514 19484 19195 19096 16248 16245 15790 15783 15760 15706

15420 15409 14180 14136 14112 14091 14059 13959 13331 13322 13191 13160

13150 13092 13057 13037 12928 12881 12861 12851 12667 12612 12601 12590



15












2H) 13C NMR (126 MHz DMSO-d6) δ 15847 15582 15549 14984 13887 13832 13789

13216 13198 13149 12973 12941 12906 12826 12778 12713 12643 12626 12569


3331







16




288 N 422


















17




1893 cm-1 in DMF16







days

74757677787980818283848586878889909192f1 (ppm)

199

195

416

108

201

220

192

192

200

096

200

7727374757677787980818283848586878889909192f1 (ppm)

088

098

099

106

198

328

099

088

300

107

088

092

090

095

084

092

102

A

B

18














19





















20





Figure A9)7980








N

NRe

OC

OCCl

CO

21



cis-Re2Cl2 -177 -187 -234 -265

KC = 50

trans-Re2Cl2 -178 -188 -240 -267

KC = 50

Re(bpy)(CO)3Cl -180 -225 - - D = 540 x 10-6 cm2 s-1

anthryl-Re -182 -229 -254 - D = 548 x 10-6 cm2 s-1











22




119894119894119888119888119888119888119888119888 = 119899119899119888119888119888119888119888119888119865119865119865119865[119888119888119888119888119888119888](119863119863119896119896119888119888119888119888119888119888[119878119878]119910119910)12 (1)

B

D

23













A B

24






Rate = minus[CO2]







B

25




















26








substrate5859

119879119879119879119879119865119865 = 119896119896119888119888119888119888119888119888[1198621198621198791198792] = 1198651198651198651198651198991198991199011199013

11987711987711987711987704463119899119899119888119888119888119888119888119888

21198941198941198881198881198881198881198881198881198941198941199011199012 (2)










119894119894119894119894119901119901

=224

119877119877119877119877119865119865119865119865119899119899119901119901

32119896119896119888119888119888119888119888119888[1198621198621198621198622]

1+119890119890119890119890119890119890 119865119865119877119877119877119877(119864119864minus1198641198641198881198881198881198881198881198882) (3)

27






















28












29





into account100

C

A B

D

30

119864119864 = 1198641198641198621198621198621198622119862119862119862119862(119863119863119863119863119865119865)0 minus 00592 ∙ 119901119901119901119901119888119888 (4)









TOF (s-1) eq 3

Ecat2

(120578120578)a Ecat2

(120578120578)b

cis-Re2Cl2 353 110 -229 (156)

-209 (092)

trans-Re2Cl2 229 44 -234 (161)

-195 (078)

Re(bpy)(CO)3Cl 111 15 -222 (149)

-204 (087)

anthryl-Re 192 41 -226 (153)

-218 (101)


0







31





















32





















33













B

cis-Re2Cl2

34











D

35






















36














+endash

-


37










38


15 Conclusion







NN

NN

Re ReOC

COOCOC CO

O CO

O

NN

NN

Re ReClOC

COOCOC CO

Cl CO

NN

NN

Re ReOC

COOCOC CO

CO

+2e -2Cl__

NN

NN

Re ReOC

COOCOC CO

O CO

HO

NN

NN

Re ReOCOC

COOCOC CO

CO

+H+

H2O

+e_

CO

+

+CO2

+H+ e_

39



















bond formation

40

CHAPTER II



21 Introduction










improved





41







Re2Cl2








N

N

N

N

Re

Re

OC

OC

OC

OCCl

OC

CO

HOO

NN

NN

Re Re0OC

COOCOC CO

Cl CON

NN

N

Re ReOC

COOCOC CO

O CO

O

N

N

N

N

Re

Re

OC

OC

OC

OCCl

CO

OC

CO

42


















such as BIH

43













44












and





NN

NN

Re ReClOC

COOCOC CO

Cl CON

N

N

N

Re

Re

OC

OC

OC

OCCl

Cl

OC

CO

N

NRe

OC

OCCl

CO

N

NRe

Cl

CO

CO

CO

45





















46






















47


















(1a)



48






















49





















50


232 Photocatalysis








51


















infra)

52
















53






















54

233 Quantum yield













55


24 Conclusion







56










57

CHAPTER III




31 Introduction







energy

58










59
















60













61









structure








62






















63

















64


















65


66








in Figure 25


67
















68
















transition state






69







energetics










70















71






bonded atoms









72






















73






















74












75













76




77



446 02

433 17

489 19









78









dihedral angle







79






















80








portion of the PES



81

















82






















83
















DHDAP products

84









85










86

















87














88
















89














transition state

90










activation barrier

91













92





93

35 Conclusion





















94






















95















the MRMP2 results

96

CHAPTER IV



41 Introduction















97






















98



















energy release

99


431 Benzvalene













100













101












102



















103














104












105





106

432 Benzvalyne







in Figure 48


107









108














109






















110








111




44 Conclusion
















112






kcal mol-1 barrier

113


















114




lone pair electrons









115

BIBLIOGRAPHY

116






305 (5682) 362ndash366






38 (1) 89ndash99





1399



117






7 (1) 70ndash88








536ndash538



1984 328ndash330




118





3387






2966ndash2974



Chem 2010 49 (20) 9283ndash9289








119








(5) 2966ndash2976



13993ndash13996




3214ndash3226



354ndash363




120




Soc 2015 137 (42) 13679ndash13690




3746ndash3754




10725







Am Chem Soc 2016 138 (6) 1938ndash1946



121






487ndash495






(10) 2931ndash2932



1988 110 (6) 1666ndash1671


Am Chem Soc 1995 117 (13) 3835ndash3847





122

Chem A 2009 113 (30) 8724ndash8730



Chem A 1999 103 (51) 11253ndash11256


















123





2003 125 (39) 11976ndash11987






5180ndash5186



7374ndash7376








124



6030



2012 41 (16) 5026ndash5037







14598ndash14607




138 (26) 8184ndash8193





125




Inorg Chem 2017 56 (7) 4176ndash4185



4593ndash4597



Madison WI 2000











2015 71 9ndash18

126




263ndash272




Trans 2012 41 (18) 5526ndash5541








2011 40 (10) 2225ndash2233






127


















1964 36 (4) 706ndash723



9983ndash10002

128



















(27) 11235ndash11242



129



8309ndash8318







2012 109 (39) 15646ndash15650



9329





463ndash469




130







(10) 2956ndash2962















131





7708






2012 41 (16) 5026ndash5037




14413ndash14424







132

1997 119 (45) 11012ndash11022



2001 105 (35) 8154ndash8161











2017 7 (1) 154ndash160




2013 135 (40) 15018ndash15025



133




2014 136 (48) 16768ndash16771








44 6311ndash6318



849ndash858



11806




134

135






Chem 2003 68 (23) 9081ndash9087







1358ndash1371




380




135


B01 2016





Chem A 2017 121 (46) 8899ndash8911




Soc 1975 97 (10) 2932ndash2933





1993 412 412ndash414



Soc 1998 120 (23) 5741ndash5750



136

(5) 1202ndash1204












Chem Phys 2012 14 (27) 9722ndash9728







1997 2 2761ndash2764


137









138

LIST OF APPENDICES

139

APPENDIX A

140


141

NN

NN

Re ReClOC

COOCOC CO

Cl CO

cis-Re2Cl2(CS

symmetric Cl-in)


1Cl-in 1Cl-out)

N

N

N

N

Re

Re

OC

OC

OC

OCCl

Cl

OC

CO

NN

NN

Re ReOCCl

COOCOC CO

CO Cl

cis 2


NN

NN

Re ReClCl

COOCOC CO

CO CO

cis 3

(asymmetric C1)

NN

NN

Re ReOCOC

COOCOC CO

Cl Cl

trans 2


N

N

N

N

Re

Re

OC

OC

OC

OCCl

CO

Cl

CO

N

N

N

N

Re

Re

OC

OC

OC

OCOC

Cl

OC

Cl

N

N

N

N

Re

Re

OC

OC

OC

OCOC

CO

Cl

Cl

cis 4

(asymmetric C1)

enantiomers

same

trans 3


1 2

4

6

7

5

3

142




714

717

718

724

725

727

733

743

744

748

750

752

753

755

760

762

764

765

769

771

773

774

774

776

783

788

790

791

800

802

803

834

835

837

839

840

842

856

858

860

862

868

869

872

874

876

878

888

898

899

900

902

903

904

7273747576777879808182838485868788899091f1 (ppm)

143



144



145







intersecting waves

119894119894119890119890 = 04463119899119899119865119865119865119865119862119862 119899119899119865119865νD119877119877119877119877

12

Equation 1





146





-15 -18 -21 -24 -27-40

-20

0

20

40

60

80

Cur

rent

micro

A

Potential V vs Fc+0


147



A B

B

148


149


150


151

A

B

152







153


C D

154



A B

B

155


156



NN

NN

Re ReOC

COOCOC CO

O CO

O

NN

NN

Re ReClOC

COOCOC CO

Cl CO

NN

NN

Re ReOC

COOCOC CO

CO

+2e -2Cl__

NN

NN

Re ReOC

COOCOC CO

O CO

HO

NN

NN

Re ReOCOC

COOCOC CO

CO

+H+

H2O

+e_

CO

+

+CO2

+H+ e_

157


158


159


160



161


162


163



164


165


166


167


168


169


170


171


172


173



174


175



176


177




178




179


6971

7375

7779

8183

8587

8991

9395

9799

101f1 (ppm

)

201

214411395206

206

206

200

104

105

732732732733733733733734734756756757758759759767767768768768769769770770771774775775775775776776776777777782782782783784784797797797798798799827828861861861861861862862862862883980

NN

NN1

180

110115

120125

130135

140145

150155

160165

f1 (ppm)

11861

11996

1236112384124921255012691127381290612914

13155

137011378513798

14901

1545215489

15760

NN

NN1

181

7374

7576

7778

7980

8182

8384

8586

8788

8990

9192

93f1 (ppm

)

199

195

416

108

201

220192

192

200

096

200

753754760762

773773774776783788790791

834835837838840

868869876878

887

903904

NN

NN

ReRe

ClO

C

COO

CO

CCO

ClCO

cis -Re2 Cl2

182

DM

F

120125

130135

140145

150155

160165

170175

180185

190195

200205

f1 (ppm)

12404124941259312610126821283212848128711287713102131421315713190133411407714111

15410

1575715822

16187

1950719509

19947

NN

NN

ReRe

ClO

C

COO

CO

CCO

ClCO

cis -Re2 Cl2

183

7172

7374

7576

7778

7980

8182

8384

8586

8788

8990

9192

93f1 (ppm

)

088

098099106

198

328

099

088

300

107

088092

090095

084

092102

733743744748750752753755764765769771772774775781783784800802803

834835837840842843856858860862872873876878

887

897899900901

trans-Re2 Cl2

NN

N N

Re Re

OC

OC

OC

OC

Cl

Cl

OC

CO

184

105110

115120

125130

135140

145150

155160

165170

175180

185190

195200

205f1 (ppm

)

12392124391244212590126011261212667128511286112881129281303713057130921315013160131911332213331139591405914091141121413614180

154091542015706157601578315790162451624816315 DMF-d7

19096191951948419514

1988319936

DM

F

trans-Re2 Cl2

NN

N N

Re Re

OC

OC

OC

OC

Cl

Cl

OC

CO

185

6970

7172

7374

7576

7778

7980

8182

8384

8586

8788

8990

9192

9394

f1 (ppm)

202

112

108

102

103110108

107109104

098

097

100101096

747748749750753755756764766766767772774784786791792793793794795799801812814817818820823824840842

851853

872875876884

NN

2

186

114116

118120

122124

126128

130132

134136

138140

142144

146148

150152

154156

158160

162164

f1 (ppm)

1195712107124791248612550125691262612643127131277812826129061294112973131491319813216

137891383213887

14984

1554915582

15847

NN

2

187

APPENDIX B

188


(log ε)

120582120582119898119898119888119888119890119890119890119890119898119898 119899119899119899119899 λ1 λ2

ℎ120596120596 119888119888119899119899minus1

λ2



anthryl-Re 252 (480) 296 (415 366 (398)

570 688 764 1440

420 6 23

430 (1)

cis-Re2Cl2 258 (485) 296 (442) 380 (412)

592 700 776 1400

210 15 65

440 (1) 520 (1)

trans-Re2Cl2 258 (470) 296 (427) 376 (395)

598 698 772 1370

200 15 90

440 (1) 490 (095)


355 375

375 670 ---

6 3300 410 440


189


190

191

192





193





194


195

APPENDIX C

196



2 Structure DAP1


3 Structure DAP2

x y z N -116779101 -064002001 -108525395 C 068300301 075432998 -125431597 C -147904301 -010512900 018798700 C 148783505 028317201 -007852600

197

C 086488998 -000468100 110520506 C -060514897 007661000 123283005 H 006928100 161709297 -097713298 H 132201004 103113604 -208814597 H -254451108 -006943700 036536899 H 255957389 017099699 -017685100 H 144391096 -028888100 197464800 H -102901101 024935301 221440911 N -019210300 -032655400 -173923600

4 Structure NdisTS


5 Structure CdisTS


198

H -162471807 100128031 -085891795


7 Structure CconTS1


8 Structure NconInt

x y z N -117254436 -012935539 -103004634 C 114911330 052507800 -132641387 C -120073497 -078021890 027967709

199

C 134310114 -015687630 -002968836 C 069569921 037333986 107144785 C -048748320 -048004261 141496575 H 133888507 159884501 -131786120 H 169165754 009332362 -216674495 H -209250116 -139012527 032793716 H 135121119 -123951328 -009737577 H 064599955 144558704 123436141 H -081668174 -079587555 239674282 N -030165136 040838382 -168327153

9 Structure CconInt



x y z N -122473168 -045778599 -113910139 C 094505334 056573945 -136906683 C -131874728 -057033855 028926978 C 141338336 001856516 -006715097 C 073123562 049870428 117475450 C -057058573 -001180191 135865033 H 081215769 165091348 -134124863 H 163488150 034631550 -218331766 H -227999783 -100280988 053255856 H 165092111 -104281521 -007590441 H 117330158 121783650 185320687

200

H -107045138 005085879 231917119 N -035554022 002986831 -183606148



12 Structure DATCA


13 Structure DHDAP1

x y z

201


14 Structure DHDAP2



x y z N -142339540 -014606592 -116566598 C 093296069 025221679 -126147401 C -140808904 -032721406 022840041

202

C 119161737 -016610871 018556029 C 084130841 081545776 126951730 C -012877002 -034134027 101129293 H 080472010 133444512 -132227707 H 179706573 000164181 -187867403 H -235516500 -018690881 072857887 H 200624251 -086340731 035096633 H 139543521 092786473 219372249 H -011925846 -106822538 181810999 N -023407100 -035943642 -187034750 H -186182213 070168203 -147589076 H -010957908 -135344136 -195132947




x y z N -139562595 013293861 -109109366 C 099973285 019917566 -139172935 C -128806067 019103202 034260291 C 129041827 019030157 008237755 C 011506672 024624294 103696835 C -077405405 -098817056 111280930

203

H 101604879 123224723 -176587749 H 177840137 -033207700 -194385386 H -209643722 075877380 078947771 H 225147820 055132854 042733517 H 023269734 084052205 193693876 H -118028319 -148607981 198114049 N -027926472 -037997854 -177376115 H -158354163 104699314 -146162188 H -027862626 -137567961 -164485288




x y z N -143094933 000844477 -105635679 C 098796737 019592127 -131666112 C -139533913 -048966303 027399421 C 113849020 -002605952 017835093 C 054325736 089400637 112329757 C -024462490 -043452144 110718977 H 113207793 126165700 -151517606 H 175230050 -034002155 -188157892 H -231300664 -094758868 062348062

204

H 186804652 -073859274 054489440 H 004017371 175133789 067512351 H -011543095 -115248680 190509605 N -030366421 -020636971 -186336851 H -177593493 094211507 -117049420 H -029553342 -118461883 -208670139




x y z N -137007999 021642189 -103387082 C 101358879 009395494 -136566508 C -117764771 048460183 031954116 C 124384856 -023482305 009737201

C -016166560 -002143468 113447988 C 062831956 -134321129 076988173 H 116087043 116113365 -154630864 H 172647870 -044072470 -199733388 H -194308221 112372172 074224061 H 196049356 037644607 063625616 H -003499719 042012647 211345911 H 005090978 -197989404 009782664

205

N -032054877 -028873754 -181068313 H -182399678 097171456 -150863016 H -039848125 -128864574 -180960560





206





207





x y z N -150680757 056806660 -130433857

208

C 090254611 -013684431 -134248567 C -133901668 018480022 005263753 C 122509563 -068525136 007712884 C -045107952 076213592 092525667 C 066651374 -021551019 124015796 H 128556395 088743246 -137062228 H 151083350 -069635767 -205396152 H -155124116 -086979580 018505041 H 208378029 -134905469 012883927 H -018387491 181044579 081894964 H 104705095 -047549337 222000599 N -043426350 -010652254 -197062349 H -136226058 155375171 -143762600 H -075494838 -103908885 -215765285




x y z N -095442176 070564193 -090830022 C 109275067 -032066563 -159886014 C -129964244 034616992 040946886 C 153150833 -012862645 -017070051

209

C -051763374 -047516546 124236357 C 080180967 -090327680 089841759 H 152177787 045718437 -223145628 H 141152573 -128543031 -200184107 H -224236107 073953104 076580024 H 177199173 089397639 010826312 H -098024762 -082737643 215669823 H 125232351 -175105810 139811301 N -036664572 -028272822 -171884358 H -172617841 110976660 -139820719 H -073830664 -118157279 -145777547




x y z N -137026465 073302871 -128783345 C 087258899 -026980808 -142273438 C -154870033 032182592 005344129 C 116283774 -062507212 003527457 C -060129660 069691128 116412342 C 062601334 -001556111 119647968 H 141744506 066357487 -160980988

210

H 135420501 -101914442 -205298281 H -188953984 -070950902 010131884 H 209415388 -116732562 016407259 H -087284940 139373589 194623566 H 121124625 -005525590 210910273 N -046208549 -009558035 -198351347 H -105760002 168298090 -136993039 H -091536391 -098043090 -211986423

33 Structure TATCE


34 Structure TAP1


211




x y z N -130169976 019081797 -104405200 N 094327176 005109686 -123695779 C -121334004 030604666 032166755 C 123439634 -020356037 014254661 C 004350619 -000710853 108998549 C 064197320 -138673258 087150085 H 156055403 -038587660 -189167881 H -215111351 045885873 083115613

212

H 220896363 016127288 043982437 H 018502170 049485105 203912592 H 108914125 -205898929 158883250 N -030465758 003788886 -175479543







213










214







215

N3disTS2 -3176147485780 0093452 -3185162733931 -319109702140





216


217

APPENDIX D

218



2 Structure benzene



C -049969479 058574504 -058668292 C -009237672 -074989456 -045842883 C 103684449 -075878704 058275461 C -129300070 -015087587 053330708 C -082796496 -042341381 185065973 C 056331784 -064315730 185904157 H -101842010 096551085 -144943500 H -021508378 -155600154 -116254115

219

H 206526399 -074706024 028235289 H -233259010 -025569454 028742656 H -147755671 -048780558 269919682 H 117592144 -063192546 273840833



5 Structure conTS1a


6 Structure conTS1b

x y z C -050297093 057183838 -051857948 C 011780674 -068796760 -050674665 C 117886078 -091360807 057008582 C -138284039 -021255155 045741639 C -079290003 -026335379 172978771 C 064550996 -057442611 176313233 H 004066788 141775155 -013330726

220

H -024384066 -149950397 -110985982 H 214899445 -133708191 041018009 H -238862038 -051306462 023680490 H -137164462 -027439317 263406634 H 117979980 -062746698 269191432


C -060312861 033196312 -060104370 C 040970480 -069692659 -072337109 C 127138186 -078242040 051838052 C -151094031 008356415 058478689 C -086735332 -036093181 168573689 C 058521593 -064758307 167377901 H -028780583 135953712 -070557755 H 010424759 -165644002 -111363649 H 230138612 -108459997 049898896 H -254118514 038453919 060916448 H -139321041 -047924933 261498356 H 107564771 -078701591 261932731

8 Structure conInta


9 Structure conIntb

x y z C -051464897 034783122 -048861307 C 031462818 -074718034 -062273878 C 129794645 -076641470 054574531 C -154038537 005896322 060560381 C -087581515 -037048936 170687735 C 059228200 -064087760 169694412

221

H -002741032 130146420 -033919087 H -017220303 -170378208 -075352222 H 233453703 -104218507 052124327 H -257708979 033494130 061710888 H -139146316 -049250481 264236450 H 107345223 -077493781 264900017


C -009655527 046972793 -008906191 C -015227714 -094399583 -031827629 C 096095592 -041598082 063547862 C -123455715 -032644540 061718422 C -078297228 -057163441 201951647 C 046763608 -062262678 202995729 H -005597737 133870459 -071054584 H -017067322 -157307601 -118251884 H 198582458 -040685388 032961217 H -225004411 -023404928 029431415


C -085433865 007954445 -050540119 C 045567364 -051211542 -056695950 C 111552680 -095593274 057378685 C -153788245 023954958 072220904 C -077983809 -023981614 178692305 C 035904256 -075357455 172803020 H -131895959 040563443 -141686261 H 092737263 -060839272 -152674186 H 209028578 -139730299 053802228 H -251223373 067773306 078508759


C -057148534 064626724 -053885663 C -007987246 -074889797 -042853338 C 103785706 -090788382 059108502 C -131887484 -019899753 047291785 C -075266618 -029607776 183234119 C 048937288 -057841164 184531891 H -100361979 109947145 -140774906 H -018274766 -144842732 -123862195 H 207025957 -100489724 033048084

222


x y z C -048499542 057807237 -044684583 C -018107219 -087599397 -042789406 C 095849288 -077209949 049913400 C -131527638 -025317946 050453913 C -077220047 -035460770 189710152 C 045264027 -060662371 186098838 H 006353579 149203587 -037687969 H -026955703 -155766630 -125254023 H 198156440 -073115003 019051071 H -234816957 -039383724 025838998


C -056745547 058684391 -048268569 C 015725785 -068826091 -049418423 C 115661573 -093949485 059854102 C -141760385 -023299107 047563148 C -070996094 -020483841 169769883 C 057978088 -046565640 174749911 H -010151576 150768197 -018310136 H -005886872 -142647159 -124150288 H 202429724 -155759370 050416756 H -242468691 -054710895 029699609


C -059775037 062431282 -046530423 C -012702130 -081251937 -042224678 C 099712479 -090821701 054368252 C -132997572 -027527353 048931655 C -075663209 -031396541 187261868 C 046679676 -059068650 185656762 H -005315014 151507330 -022183387 H -022591665 -146724463 -126617146 H 202726650 -101349378 027691770 H -233505273 -056371480 025802734

223




benzvalyne





224



benzyne

MOs 15 16 17 18 19 20 21 21 23 24 25 26 disTSprime 1981 1969 1962 1908 1697 1236 0767 0303 0091 0041 0024 0020



225

226

VITA

WEIWEI YANG











227







ABSTRACT


ACKNOWLEDGEMENTS

LIST OF TABLES

LIST OF FIGURES

INTRODUCTION


11 Introduction












15 Conclusion


21 Introduction









232 Photocatalysis

233 Quantum yield

24 Conclusion


31 Introduction













35 Conclusion


41 Introduction



431 Benzvalene



432 Benzvalyne



44 Conclusion

CONCLUSION

BIBLIOGRAPHY

List of APPENDICES

APPENDIX A

APPENDIX B

APPENDIX C

APPENDIX D

VITA

iii










iv


CO2 carbon dioxide

CO carbon monoxide





DAP 3H-12-diazepine












v






TS transition state







ν scan rate







vi







T temperature



TON turnover number



MeOH methanol

PhOH phenol


PS photosensitizer


TEA triethylamine

φ quantum yield

vii








viii

ACKNOWLEDGEMENTS
















ix










x




LIST OF TABLES xiv

LIST OF FIGURES xv

INTRODUCTION 1



11 Introduction 7










xi



15 Conclusion 38



CHROMOPHORE 40

21 Introduction 40











24 Conclusion 55

xii




31 Introduction 57







35 Conclusion 93



41 Introduction 96



431 Benzvalene 99

432 Benzvalyne 106

44 Conclusion 111

xiii

CONCLUSION 113

BIBLIOGRAPHY 115

APPENDIX A 139

APPENDIX B 187

APPENDIX C 195

APPENDIX D 217

VITA 226

xiv

LIST OF TABLES


pH 7 vs NHE) 2















xv

LIST OF FIGURES











blue line 22








xvi










solutions 34





38



(2) 41


xvii












example above 55








xviii



66







74









xix



isomerization 85










isomerizations 92



100



xx








1

INTRODUCTION



















2

















3






















4












5











6


















conclusion44-46

7

CHAPTER I



11 Introduction














8









Cl ClO

O 1 Zn NH4OH (20) 80 oC 5 h

2 HCl iPrOH

Cl Cl

2 B B

Pd2(dba)3 + 4Xphos

dioxane 90 oC 2 d

B BO O O O

O

O O

O

N NBr


NN

NN

NN

NN

Re ReClOC

COOCOC CO

Cl CO

cis-Re2Cl2 1

Re(CO)5Cl

toluene ∆1 d

1a88

1b88

86

trans-Re2Cl2

N

N

N

N

Re

Re

OC

OC

OC

OCCl

Cl

OC

CO

+

41 20

9





















10





















11


electrode















CIF file




12




















13
















14901 13799 13785 13701 13155 12914 12906 12738 12691 12550 12492 12384






14








2H) 13C NMR (126 MHz DMF-d7) δ 19947 19509 19507 16187 15822 15757 15410

14111 14077 13341 13190 13157 13142 13102 12877 12871 12848 12832 12682








19936 19883 19514 19484 19195 19096 16248 16245 15790 15783 15760 15706

15420 15409 14180 14136 14112 14091 14059 13959 13331 13322 13191 13160

13150 13092 13057 13037 12928 12881 12861 12851 12667 12612 12601 12590



15












2H) 13C NMR (126 MHz DMSO-d6) δ 15847 15582 15549 14984 13887 13832 13789

13216 13198 13149 12973 12941 12906 12826 12778 12713 12643 12626 12569


3331







16




288 N 422


















17




1893 cm-1 in DMF16







days

74757677787980818283848586878889909192f1 (ppm)

199

195

416

108

201

220

192

192

200

096

200

7727374757677787980818283848586878889909192f1 (ppm)

088

098

099

106

198

328

099

088

300

107

088

092

090

095

084

092

102

A

B

18














19





















20





Figure A9)7980








N

NRe

OC

OCCl

CO

21



cis-Re2Cl2 -177 -187 -234 -265

KC = 50

trans-Re2Cl2 -178 -188 -240 -267

KC = 50

Re(bpy)(CO)3Cl -180 -225 - - D = 540 x 10-6 cm2 s-1

anthryl-Re -182 -229 -254 - D = 548 x 10-6 cm2 s-1











22




119894119894119888119888119888119888119888119888 = 119899119899119888119888119888119888119888119888119865119865119865119865[119888119888119888119888119888119888](119863119863119896119896119888119888119888119888119888119888[119878119878]119910119910)12 (1)

B

D

23













A B

24






Rate = minus[CO2]







B

25




















26








substrate5859

119879119879119879119879119865119865 = 119896119896119888119888119888119888119888119888[1198621198621198791198792] = 1198651198651198651198651198991198991199011199013

11987711987711987711987704463119899119899119888119888119888119888119888119888

21198941198941198881198881198881198881198881198881198941198941199011199012 (2)










119894119894119894119894119901119901

=224

119877119877119877119877119865119865119865119865119899119899119901119901

32119896119896119888119888119888119888119888119888[1198621198621198621198622]

1+119890119890119890119890119890119890 119865119865119877119877119877119877(119864119864minus1198641198641198881198881198881198881198881198882) (3)

27






















28












29





into account100

C

A B

D

30

119864119864 = 1198641198641198621198621198621198622119862119862119862119862(119863119863119863119863119865119865)0 minus 00592 ∙ 119901119901119901119901119888119888 (4)









TOF (s-1) eq 3

Ecat2

(120578120578)a Ecat2

(120578120578)b

cis-Re2Cl2 353 110 -229 (156)

-209 (092)

trans-Re2Cl2 229 44 -234 (161)

-195 (078)

Re(bpy)(CO)3Cl 111 15 -222 (149)

-204 (087)

anthryl-Re 192 41 -226 (153)

-218 (101)


0







31





















32





















33













B

cis-Re2Cl2

34











D

35






















36














+endash

-


37










38


15 Conclusion







NN

NN

Re ReOC

COOCOC CO

O CO

O

NN

NN

Re ReClOC

COOCOC CO

Cl CO

NN

NN

Re ReOC

COOCOC CO

CO

+2e -2Cl__

NN

NN

Re ReOC

COOCOC CO

O CO

HO

NN

NN

Re ReOCOC

COOCOC CO

CO

+H+

H2O

+e_

CO

+

+CO2

+H+ e_

39



















bond formation

40

CHAPTER II



21 Introduction










improved





41







Re2Cl2








N

N

N

N

Re

Re

OC

OC

OC

OCCl

OC

CO

HOO

NN

NN

Re Re0OC

COOCOC CO

Cl CON

NN

N

Re ReOC

COOCOC CO

O CO

O

N

N

N

N

Re

Re

OC

OC

OC

OCCl

CO

OC

CO

42


















such as BIH

43













44












and





NN

NN

Re ReClOC

COOCOC CO

Cl CON

N

N

N

Re

Re

OC

OC

OC

OCCl

Cl

OC

CO

N

NRe

OC

OCCl

CO

N

NRe

Cl

CO

CO

CO

45





















46






















47


















(1a)



48






















49





















50


232 Photocatalysis








51


















infra)

52
















53






















54

233 Quantum yield













55


24 Conclusion







56










57

CHAPTER III




31 Introduction







energy

58










59
















60













61









structure








62






















63

















64


















65


66








in Figure 25


67
















68
















transition state






69







energetics










70















71






bonded atoms









72






















73






















74












75













76




77



446 02

433 17

489 19









78









dihedral angle







79






















80








portion of the PES



81

















82






















83
















DHDAP products

84









85










86

















87














88
















89














transition state

90










activation barrier

91













92





93

35 Conclusion





















94






















95















the MRMP2 results

96

CHAPTER IV



41 Introduction















97






















98



















energy release

99


431 Benzvalene













100













101












102



















103














104












105





106

432 Benzvalyne







in Figure 48


107









108














109






















110








111




44 Conclusion
















112






kcal mol-1 barrier

113


















114




lone pair electrons









115

BIBLIOGRAPHY

116






305 (5682) 362ndash366






38 (1) 89ndash99





1399



117






7 (1) 70ndash88








536ndash538



1984 328ndash330




118





3387






2966ndash2974



Chem 2010 49 (20) 9283ndash9289








119








(5) 2966ndash2976



13993ndash13996




3214ndash3226



354ndash363




120




Soc 2015 137 (42) 13679ndash13690




3746ndash3754




10725







Am Chem Soc 2016 138 (6) 1938ndash1946



121






487ndash495






(10) 2931ndash2932



1988 110 (6) 1666ndash1671


Am Chem Soc 1995 117 (13) 3835ndash3847





122

Chem A 2009 113 (30) 8724ndash8730



Chem A 1999 103 (51) 11253ndash11256


















123





2003 125 (39) 11976ndash11987






5180ndash5186



7374ndash7376








124



6030



2012 41 (16) 5026ndash5037







14598ndash14607




138 (26) 8184ndash8193





125




Inorg Chem 2017 56 (7) 4176ndash4185



4593ndash4597



Madison WI 2000











2015 71 9ndash18

126




263ndash272




Trans 2012 41 (18) 5526ndash5541








2011 40 (10) 2225ndash2233






127


















1964 36 (4) 706ndash723



9983ndash10002

128



















(27) 11235ndash11242



129



8309ndash8318







2012 109 (39) 15646ndash15650



9329





463ndash469




130







(10) 2956ndash2962















131





7708






2012 41 (16) 5026ndash5037




14413ndash14424







132

1997 119 (45) 11012ndash11022



2001 105 (35) 8154ndash8161











2017 7 (1) 154ndash160




2013 135 (40) 15018ndash15025



133




2014 136 (48) 16768ndash16771








44 6311ndash6318



849ndash858



11806




134

135






Chem 2003 68 (23) 9081ndash9087







1358ndash1371




380




135


B01 2016





Chem A 2017 121 (46) 8899ndash8911




Soc 1975 97 (10) 2932ndash2933





1993 412 412ndash414



Soc 1998 120 (23) 5741ndash5750



136

(5) 1202ndash1204












Chem Phys 2012 14 (27) 9722ndash9728







1997 2 2761ndash2764


137









138

LIST OF APPENDICES

139

APPENDIX A

140


141

NN

NN

Re ReClOC

COOCOC CO

Cl CO

cis-Re2Cl2(CS

symmetric Cl-in)


1Cl-in 1Cl-out)

N

N

N

N

Re

Re

OC

OC

OC

OCCl

Cl

OC

CO

NN

NN

Re ReOCCl

COOCOC CO

CO Cl

cis 2


NN

NN

Re ReClCl

COOCOC CO

CO CO

cis 3

(asymmetric C1)

NN

NN

Re ReOCOC

COOCOC CO

Cl Cl

trans 2


N

N

N

N

Re

Re

OC

OC

OC

OCCl

CO

Cl

CO

N

N

N

N

Re

Re

OC

OC

OC

OCOC

Cl

OC

Cl

N

N

N

N

Re

Re

OC

OC

OC

OCOC

CO

Cl

Cl

cis 4

(asymmetric C1)

enantiomers

same

trans 3


1 2

4

6

7

5

3

142




714

717

718

724

725

727

733

743

744

748

750

752

753

755

760

762

764

765

769

771

773

774

774

776

783

788

790

791

800

802

803

834

835

837

839

840

842

856

858

860

862

868

869

872

874

876

878

888

898

899

900

902

903

904

7273747576777879808182838485868788899091f1 (ppm)

143



144



145







intersecting waves

119894119894119890119890 = 04463119899119899119865119865119865119865119862119862 119899119899119865119865νD119877119877119877119877

12

Equation 1





146





-15 -18 -21 -24 -27-40

-20

0

20

40

60

80

Cur

rent

micro

A

Potential V vs Fc+0


147



A B

B

148


149


150


151

A

B

152







153


C D

154



A B

B

155


156



NN

NN

Re ReOC

COOCOC CO

O CO

O

NN

NN

Re ReClOC

COOCOC CO

Cl CO

NN

NN

Re ReOC

COOCOC CO

CO

+2e -2Cl__

NN

NN

Re ReOC

COOCOC CO

O CO

HO

NN

NN

Re ReOCOC

COOCOC CO

CO

+H+

H2O

+e_

CO

+

+CO2

+H+ e_

157


158


159


160



161


162


163



164


165


166


167


168


169


170


171


172


173



174


175



176


177




178




179


6971

7375

7779

8183

8587

8991

9395

9799

101f1 (ppm

)

201

214411395206

206

206

200

104

105

732732732733733733733734734756756757758759759767767768768768769769770770771774775775775775776776776777777782782782783784784797797797798798799827828861861861861861862862862862883980

NN

NN1

180

110115

120125

130135

140145

150155

160165

f1 (ppm)

11861

11996

1236112384124921255012691127381290612914

13155

137011378513798

14901

1545215489

15760

NN

NN1

181

7374

7576

7778

7980

8182

8384

8586

8788

8990

9192

93f1 (ppm

)

199

195

416

108

201

220192

192

200

096

200

753754760762

773773774776783788790791

834835837838840

868869876878

887

903904

NN

NN

ReRe

ClO

C

COO

CO

CCO

ClCO

cis -Re2 Cl2

182

DM

F

120125

130135

140145

150155

160165

170175

180185

190195

200205

f1 (ppm)

12404124941259312610126821283212848128711287713102131421315713190133411407714111

15410

1575715822

16187

1950719509

19947

NN

NN

ReRe

ClO

C

COO

CO

CCO

ClCO

cis -Re2 Cl2

183

7172

7374

7576

7778

7980

8182

8384

8586

8788

8990

9192

93f1 (ppm

)

088

098099106

198

328

099

088

300

107

088092

090095

084

092102

733743744748750752753755764765769771772774775781783784800802803

834835837840842843856858860862872873876878

887

897899900901

trans-Re2 Cl2

NN

N N

Re Re

OC

OC

OC

OC

Cl

Cl

OC

CO

184

105110

115120

125130

135140

145150

155160

165170

175180

185190

195200

205f1 (ppm

)

12392124391244212590126011261212667128511286112881129281303713057130921315013160131911332213331139591405914091141121413614180

154091542015706157601578315790162451624816315 DMF-d7

19096191951948419514

1988319936

DM

F

trans-Re2 Cl2

NN

N N

Re Re

OC

OC

OC

OC

Cl

Cl

OC

CO

185

6970

7172

7374

7576

7778

7980

8182

8384

8586

8788

8990

9192

9394

f1 (ppm)

202

112

108

102

103110108

107109104

098

097

100101096

747748749750753755756764766766767772774784786791792793793794795799801812814817818820823824840842

851853

872875876884

NN

2

186

114116

118120

122124

126128

130132

134136

138140

142144

146148

150152

154156

158160

162164

f1 (ppm)

1195712107124791248612550125691262612643127131277812826129061294112973131491319813216

137891383213887

14984

1554915582

15847

NN

2

187

APPENDIX B

188


(log ε)

120582120582119898119898119888119888119890119890119890119890119898119898 119899119899119899119899 λ1 λ2

ℎ120596120596 119888119888119899119899minus1

λ2



anthryl-Re 252 (480) 296 (415 366 (398)

570 688 764 1440

420 6 23

430 (1)

cis-Re2Cl2 258 (485) 296 (442) 380 (412)

592 700 776 1400

210 15 65

440 (1) 520 (1)

trans-Re2Cl2 258 (470) 296 (427) 376 (395)

598 698 772 1370

200 15 90

440 (1) 490 (095)


355 375

375 670 ---

6 3300 410 440


189


190

191

192





193





194


195

APPENDIX C

196



2 Structure DAP1


3 Structure DAP2

x y z N -116779101 -064002001 -108525395 C 068300301 075432998 -125431597 C -147904301 -010512900 018798700 C 148783505 028317201 -007852600

197

C 086488998 -000468100 110520506 C -060514897 007661000 123283005 H 006928100 161709297 -097713298 H 132201004 103113604 -208814597 H -254451108 -006943700 036536899 H 255957389 017099699 -017685100 H 144391096 -028888100 197464800 H -102901101 024935301 221440911 N -019210300 -032655400 -173923600

4 Structure NdisTS


5 Structure CdisTS


198

H -162471807 100128031 -085891795


7 Structure CconTS1


8 Structure NconInt

x y z N -117254436 -012935539 -103004634 C 114911330 052507800 -132641387 C -120073497 -078021890 027967709

199

C 134310114 -015687630 -002968836 C 069569921 037333986 107144785 C -048748320 -048004261 141496575 H 133888507 159884501 -131786120 H 169165754 009332362 -216674495 H -209250116 -139012527 032793716 H 135121119 -123951328 -009737577 H 064599955 144558704 123436141 H -081668174 -079587555 239674282 N -030165136 040838382 -168327153

9 Structure CconInt



x y z N -122473168 -045778599 -113910139 C 094505334 056573945 -136906683 C -131874728 -057033855 028926978 C 141338336 001856516 -006715097 C 073123562 049870428 117475450 C -057058573 -001180191 135865033 H 081215769 165091348 -134124863 H 163488150 034631550 -218331766 H -227999783 -100280988 053255856 H 165092111 -104281521 -007590441 H 117330158 121783650 185320687

200

H -107045138 005085879 231917119 N -035554022 002986831 -183606148



12 Structure DATCA


13 Structure DHDAP1

x y z

201


14 Structure DHDAP2



x y z N -142339540 -014606592 -116566598 C 093296069 025221679 -126147401 C -140808904 -032721406 022840041

202

C 119161737 -016610871 018556029 C 084130841 081545776 126951730 C -012877002 -034134027 101129293 H 080472010 133444512 -132227707 H 179706573 000164181 -187867403 H -235516500 -018690881 072857887 H 200624251 -086340731 035096633 H 139543521 092786473 219372249 H -011925846 -106822538 181810999 N -023407100 -035943642 -187034750 H -186182213 070168203 -147589076 H -010957908 -135344136 -195132947




x y z N -139562595 013293861 -109109366 C 099973285 019917566 -139172935 C -128806067 019103202 034260291 C 129041827 019030157 008237755 C 011506672 024624294 103696835 C -077405405 -098817056 111280930

203

H 101604879 123224723 -176587749 H 177840137 -033207700 -194385386 H -209643722 075877380 078947771 H 225147820 055132854 042733517 H 023269734 084052205 193693876 H -118028319 -148607981 198114049 N -027926472 -037997854 -177376115 H -158354163 104699314 -146162188 H -027862626 -137567961 -164485288




x y z N -143094933 000844477 -105635679 C 098796737 019592127 -131666112 C -139533913 -048966303 027399421 C 113849020 -002605952 017835093 C 054325736 089400637 112329757 C -024462490 -043452144 110718977 H 113207793 126165700 -151517606 H 175230050 -034002155 -188157892 H -231300664 -094758868 062348062

204

H 186804652 -073859274 054489440 H 004017371 175133789 067512351 H -011543095 -115248680 190509605 N -030366421 -020636971 -186336851 H -177593493 094211507 -117049420 H -029553342 -118461883 -208670139




x y z N -137007999 021642189 -103387082 C 101358879 009395494 -136566508 C -117764771 048460183 031954116 C 124384856 -023482305 009737201

C -016166560 -002143468 113447988 C 062831956 -134321129 076988173 H 116087043 116113365 -154630864 H 172647870 -044072470 -199733388 H -194308221 112372172 074224061 H 196049356 037644607 063625616 H -003499719 042012647 211345911 H 005090978 -197989404 009782664

205

N -032054877 -028873754 -181068313 H -182399678 097171456 -150863016 H -039848125 -128864574 -180960560





206





207





x y z N -150680757 056806660 -130433857

208

C 090254611 -013684431 -134248567 C -133901668 018480022 005263753 C 122509563 -068525136 007712884 C -045107952 076213592 092525667 C 066651374 -021551019 124015796 H 128556395 088743246 -137062228 H 151083350 -069635767 -205396152 H -155124116 -086979580 018505041 H 208378029 -134905469 012883927 H -018387491 181044579 081894964 H 104705095 -047549337 222000599 N -043426350 -010652254 -197062349 H -136226058 155375171 -143762600 H -075494838 -103908885 -215765285




x y z N -095442176 070564193 -090830022 C 109275067 -032066563 -159886014 C -129964244 034616992 040946886 C 153150833 -012862645 -017070051

209

C -051763374 -047516546 124236357 C 080180967 -090327680 089841759 H 152177787 045718437 -223145628 H 141152573 -128543031 -200184107 H -224236107 073953104 076580024 H 177199173 089397639 010826312 H -098024762 -082737643 215669823 H 125232351 -175105810 139811301 N -036664572 -028272822 -171884358 H -172617841 110976660 -139820719 H -073830664 -118157279 -145777547




x y z N -137026465 073302871 -128783345 C 087258899 -026980808 -142273438 C -154870033 032182592 005344129 C 116283774 -062507212 003527457 C -060129660 069691128 116412342 C 062601334 -001556111 119647968 H 141744506 066357487 -160980988

210

H 135420501 -101914442 -205298281 H -188953984 -070950902 010131884 H 209415388 -116732562 016407259 H -087284940 139373589 194623566 H 121124625 -005525590 210910273 N -046208549 -009558035 -198351347 H -105760002 168298090 -136993039 H -091536391 -098043090 -211986423

33 Structure TATCE


34 Structure TAP1


211




x y z N -130169976 019081797 -104405200 N 094327176 005109686 -123695779 C -121334004 030604666 032166755 C 123439634 -020356037 014254661 C 004350619 -000710853 108998549 C 064197320 -138673258 087150085 H 156055403 -038587660 -189167881 H -215111351 045885873 083115613

212

H 220896363 016127288 043982437 H 018502170 049485105 203912592 H 108914125 -205898929 158883250 N -030465758 003788886 -175479543







213










214







215

N3disTS2 -3176147485780 0093452 -3185162733931 -319109702140





216


217

APPENDIX D

218



2 Structure benzene



C -049969479 058574504 -058668292 C -009237672 -074989456 -045842883 C 103684449 -075878704 058275461 C -129300070 -015087587 053330708 C -082796496 -042341381 185065973 C 056331784 -064315730 185904157 H -101842010 096551085 -144943500 H -021508378 -155600154 -116254115

219

H 206526399 -074706024 028235289 H -233259010 -025569454 028742656 H -147755671 -048780558 269919682 H 117592144 -063192546 273840833



5 Structure conTS1a


6 Structure conTS1b

x y z C -050297093 057183838 -051857948 C 011780674 -068796760 -050674665 C 117886078 -091360807 057008582 C -138284039 -021255155 045741639 C -079290003 -026335379 172978771 C 064550996 -057442611 176313233 H 004066788 141775155 -013330726

220

H -024384066 -149950397 -110985982 H 214899445 -133708191 041018009 H -238862038 -051306462 023680490 H -137164462 -027439317 263406634 H 117979980 -062746698 269191432


C -060312861 033196312 -060104370 C 040970480 -069692659 -072337109 C 127138186 -078242040 051838052 C -151094031 008356415 058478689 C -086735332 -036093181 168573689 C 058521593 -064758307 167377901 H -028780583 135953712 -070557755 H 010424759 -165644002 -111363649 H 230138612 -108459997 049898896 H -254118514 038453919 060916448 H -139321041 -047924933 261498356 H 107564771 -078701591 261932731

8 Structure conInta


9 Structure conIntb

x y z C -051464897 034783122 -048861307 C 031462818 -074718034 -062273878 C 129794645 -076641470 054574531 C -154038537 005896322 060560381 C -087581515 -037048936 170687735 C 059228200 -064087760 169694412

221

H -002741032 130146420 -033919087 H -017220303 -170378208 -075352222 H 233453703 -104218507 052124327 H -257708979 033494130 061710888 H -139146316 -049250481 264236450 H 107345223 -077493781 264900017


C -009655527 046972793 -008906191 C -015227714 -094399583 -031827629 C 096095592 -041598082 063547862 C -123455715 -032644540 061718422 C -078297228 -057163441 201951647 C 046763608 -062262678 202995729 H -005597737 133870459 -071054584 H -017067322 -157307601 -118251884 H 198582458 -040685388 032961217 H -225004411 -023404928 029431415


C -085433865 007954445 -050540119 C 045567364 -051211542 -056695950 C 111552680 -095593274 057378685 C -153788245 023954958 072220904 C -077983809 -023981614 178692305 C 035904256 -075357455 172803020 H -131895959 040563443 -141686261 H 092737263 -060839272 -152674186 H 209028578 -139730299 053802228 H -251223373 067773306 078508759


C -057148534 064626724 -053885663 C -007987246 -074889797 -042853338 C 103785706 -090788382 059108502 C -131887484 -019899753 047291785 C -075266618 -029607776 183234119 C 048937288 -057841164 184531891 H -100361979 109947145 -140774906 H -018274766 -144842732 -123862195 H 207025957 -100489724 033048084

222


x y z C -048499542 057807237 -044684583 C -018107219 -087599397 -042789406 C 095849288 -077209949 049913400 C -131527638 -025317946 050453913 C -077220047 -035460770 189710152 C 045264027 -060662371 186098838 H 006353579 149203587 -037687969 H -026955703 -155766630 -125254023 H 198156440 -073115003 019051071 H -234816957 -039383724 025838998


C -056745547 058684391 -048268569 C 015725785 -068826091 -049418423 C 115661573 -093949485 059854102 C -141760385 -023299107 047563148 C -070996094 -020483841 169769883 C 057978088 -046565640 174749911 H -010151576 150768197 -018310136 H -005886872 -142647159 -124150288 H 202429724 -155759370 050416756 H -242468691 -054710895 029699609


C -059775037 062431282 -046530423 C -012702130 -081251937 -042224678 C 099712479 -090821701 054368252 C -132997572 -027527353 048931655 C -075663209 -031396541 187261868 C 046679676 -059068650 185656762 H -005315014 151507330 -022183387 H -022591665 -146724463 -126617146 H 202726650 -101349378 027691770 H -233505273 -056371480 025802734

223




benzvalyne





224



benzyne

MOs 15 16 17 18 19 20 21 21 23 24 25 26 disTSprime 1981 1969 1962 1908 1697 1236 0767 0303 0091 0041 0024 0020



225

226

VITA

WEIWEI YANG











227







ABSTRACT


ACKNOWLEDGEMENTS

LIST OF TABLES

LIST OF FIGURES

INTRODUCTION


11 Introduction












15 Conclusion


21 Introduction









232 Photocatalysis

233 Quantum yield

24 Conclusion


31 Introduction













35 Conclusion


41 Introduction



431 Benzvalene



432 Benzvalyne



44 Conclusion

CONCLUSION

BIBLIOGRAPHY

List of APPENDICES

APPENDIX A

APPENDIX B

APPENDIX C

APPENDIX D

VITA

iv


CO2 carbon dioxide

CO carbon monoxide





DAP 3H-12-diazepine












v






TS transition state







ν scan rate







vi







T temperature



TON turnover number



MeOH methanol

PhOH phenol


PS photosensitizer


TEA triethylamine

φ quantum yield

vii








viii

ACKNOWLEDGEMENTS
















ix










x




LIST OF TABLES xiv

LIST OF FIGURES xv

INTRODUCTION 1



11 Introduction 7










xi



15 Conclusion 38



CHROMOPHORE 40

21 Introduction 40











24 Conclusion 55

xii




31 Introduction 57







35 Conclusion 93



41 Introduction 96



431 Benzvalene 99

432 Benzvalyne 106

44 Conclusion 111

xiii

CONCLUSION 113

BIBLIOGRAPHY 115

APPENDIX A 139

APPENDIX B 187

APPENDIX C 195

APPENDIX D 217

VITA 226

xiv

LIST OF TABLES


pH 7 vs NHE) 2















xv

LIST OF FIGURES











blue line 22








xvi










solutions 34





38



(2) 41


xvii












example above 55








xviii



66







74









xix



isomerization 85










isomerizations 92



100



xx








1

INTRODUCTION



















2

















3






















4












5











6


















conclusion44-46

7

CHAPTER I



11 Introduction














8









Cl ClO

O 1 Zn NH4OH (20) 80 oC 5 h

2 HCl iPrOH

Cl Cl

2 B B

Pd2(dba)3 + 4Xphos

dioxane 90 oC 2 d

B BO O O O

O

O O

O

N NBr


NN

NN

NN

NN

Re ReClOC

COOCOC CO

Cl CO

cis-Re2Cl2 1

Re(CO)5Cl

toluene ∆1 d

1a88

1b88

86

trans-Re2Cl2

N

N

N

N

Re

Re

OC

OC

OC

OCCl

Cl

OC

CO

+

41 20

9





















10





















11


electrode















CIF file




12




















13
















14901 13799 13785 13701 13155 12914 12906 12738 12691 12550 12492 12384






14








2H) 13C NMR (126 MHz DMF-d7) δ 19947 19509 19507 16187 15822 15757 15410

14111 14077 13341 13190 13157 13142 13102 12877 12871 12848 12832 12682








19936 19883 19514 19484 19195 19096 16248 16245 15790 15783 15760 15706

15420 15409 14180 14136 14112 14091 14059 13959 13331 13322 13191 13160

13150 13092 13057 13037 12928 12881 12861 12851 12667 12612 12601 12590



15












2H) 13C NMR (126 MHz DMSO-d6) δ 15847 15582 15549 14984 13887 13832 13789

13216 13198 13149 12973 12941 12906 12826 12778 12713 12643 12626 12569


3331







16




288 N 422


















17




1893 cm-1 in DMF16







days

74757677787980818283848586878889909192f1 (ppm)

199

195

416

108

201

220

192

192

200

096

200

7727374757677787980818283848586878889909192f1 (ppm)

088

098

099

106

198

328

099

088

300

107

088

092

090

095

084

092

102

A

B

18














19





















20





Figure A9)7980








N

NRe

OC

OCCl

CO

21



cis-Re2Cl2 -177 -187 -234 -265

KC = 50

trans-Re2Cl2 -178 -188 -240 -267

KC = 50

Re(bpy)(CO)3Cl -180 -225 - - D = 540 x 10-6 cm2 s-1

anthryl-Re -182 -229 -254 - D = 548 x 10-6 cm2 s-1











22




119894119894119888119888119888119888119888119888 = 119899119899119888119888119888119888119888119888119865119865119865119865[119888119888119888119888119888119888](119863119863119896119896119888119888119888119888119888119888[119878119878]119910119910)12 (1)

B

D

23













A B

24






Rate = minus[CO2]







B

25




















26








substrate5859

119879119879119879119879119865119865 = 119896119896119888119888119888119888119888119888[1198621198621198791198792] = 1198651198651198651198651198991198991199011199013

11987711987711987711987704463119899119899119888119888119888119888119888119888

21198941198941198881198881198881198881198881198881198941198941199011199012 (2)










119894119894119894119894119901119901

=224

119877119877119877119877119865119865119865119865119899119899119901119901

32119896119896119888119888119888119888119888119888[1198621198621198621198622]

1+119890119890119890119890119890119890 119865119865119877119877119877119877(119864119864minus1198641198641198881198881198881198881198881198882) (3)

27






















28












29





into account100

C

A B

D

30

119864119864 = 1198641198641198621198621198621198622119862119862119862119862(119863119863119863119863119865119865)0 minus 00592 ∙ 119901119901119901119901119888119888 (4)









TOF (s-1) eq 3

Ecat2

(120578120578)a Ecat2

(120578120578)b

cis-Re2Cl2 353 110 -229 (156)

-209 (092)

trans-Re2Cl2 229 44 -234 (161)

-195 (078)

Re(bpy)(CO)3Cl 111 15 -222 (149)

-204 (087)

anthryl-Re 192 41 -226 (153)

-218 (101)


0







31





















32





















33













B

cis-Re2Cl2

34











D

35






















36














+endash

-


37










38


15 Conclusion







NN

NN

Re ReOC

COOCOC CO

O CO

O

NN

NN

Re ReClOC

COOCOC CO

Cl CO

NN

NN

Re ReOC

COOCOC CO

CO

+2e -2Cl__

NN

NN

Re ReOC

COOCOC CO

O CO

HO

NN

NN

Re ReOCOC

COOCOC CO

CO

+H+

H2O

+e_

CO

+

+CO2

+H+ e_

39



















bond formation

40

CHAPTER II



21 Introduction










improved





41







Re2Cl2








N

N

N

N

Re

Re

OC

OC

OC

OCCl

OC

CO

HOO

NN

NN

Re Re0OC

COOCOC CO

Cl CON

NN

N

Re ReOC

COOCOC CO

O CO

O

N

N

N

N

Re

Re

OC

OC

OC

OCCl

CO

OC

CO

42


















such as BIH

43













44












and





NN

NN

Re ReClOC

COOCOC CO

Cl CON

N

N

N

Re

Re

OC

OC

OC

OCCl

Cl

OC

CO

N

NRe

OC

OCCl

CO

N

NRe

Cl

CO

CO

CO

45





















46






















47


















(1a)



48






















49





















50


232 Photocatalysis








51


















infra)

52
















53






















54

233 Quantum yield













55


24 Conclusion







56










57

CHAPTER III




31 Introduction







energy

58










59
















60













61









structure








62






















63

















64


















65


66








in Figure 25


67
















68
















transition state






69







energetics










70















71






bonded atoms









72






















73






















74












75













76




77



446 02

433 17

489 19









78









dihedral angle







79






















80








portion of the PES



81

















82






















83
















DHDAP products

84









85










86

















87














88
















89














transition state

90










activation barrier

91













92





93

35 Conclusion





















94






















95















the MRMP2 results

96

CHAPTER IV



41 Introduction















97






















98



















energy release

99


431 Benzvalene













100













101












102



















103














104












105





106

432 Benzvalyne







in Figure 48


107









108














109






















110








111




44 Conclusion
















112






kcal mol-1 barrier

113


















114




lone pair electrons









115

BIBLIOGRAPHY

116






305 (5682) 362ndash366






38 (1) 89ndash99





1399



117






7 (1) 70ndash88








536ndash538



1984 328ndash330




118





3387






2966ndash2974



Chem 2010 49 (20) 9283ndash9289








119








(5) 2966ndash2976



13993ndash13996




3214ndash3226



354ndash363




120




Soc 2015 137 (42) 13679ndash13690




3746ndash3754




10725







Am Chem Soc 2016 138 (6) 1938ndash1946



121






487ndash495






(10) 2931ndash2932



1988 110 (6) 1666ndash1671


Am Chem Soc 1995 117 (13) 3835ndash3847





122

Chem A 2009 113 (30) 8724ndash8730



Chem A 1999 103 (51) 11253ndash11256


















123





2003 125 (39) 11976ndash11987






5180ndash5186



7374ndash7376








124



6030



2012 41 (16) 5026ndash5037







14598ndash14607




138 (26) 8184ndash8193





125




Inorg Chem 2017 56 (7) 4176ndash4185



4593ndash4597



Madison WI 2000











2015 71 9ndash18

126




263ndash272




Trans 2012 41 (18) 5526ndash5541








2011 40 (10) 2225ndash2233






127


















1964 36 (4) 706ndash723



9983ndash10002

128



















(27) 11235ndash11242



129



8309ndash8318







2012 109 (39) 15646ndash15650



9329





463ndash469




130







(10) 2956ndash2962















131





7708






2012 41 (16) 5026ndash5037




14413ndash14424







132

1997 119 (45) 11012ndash11022



2001 105 (35) 8154ndash8161











2017 7 (1) 154ndash160




2013 135 (40) 15018ndash15025



133




2014 136 (48) 16768ndash16771








44 6311ndash6318



849ndash858



11806




134

135






Chem 2003 68 (23) 9081ndash9087







1358ndash1371




380




135


B01 2016





Chem A 2017 121 (46) 8899ndash8911




Soc 1975 97 (10) 2932ndash2933





1993 412 412ndash414



Soc 1998 120 (23) 5741ndash5750



136

(5) 1202ndash1204












Chem Phys 2012 14 (27) 9722ndash9728







1997 2 2761ndash2764


137









138

LIST OF APPENDICES

139

APPENDIX A

140


141

NN

NN

Re ReClOC

COOCOC CO

Cl CO

cis-Re2Cl2(CS

symmetric Cl-in)


1Cl-in 1Cl-out)

N

N

N

N

Re

Re

OC

OC

OC

OCCl

Cl

OC

CO

NN

NN

Re ReOCCl

COOCOC CO

CO Cl

cis 2


NN

NN

Re ReClCl

COOCOC CO

CO CO

cis 3

(asymmetric C1)

NN

NN

Re ReOCOC

COOCOC CO

Cl Cl

trans 2


N

N

N

N

Re

Re

OC

OC

OC

OCCl

CO

Cl

CO

N

N

N

N

Re

Re

OC

OC

OC

OCOC

Cl

OC

Cl

N

N

N

N

Re

Re

OC

OC

OC

OCOC

CO

Cl

Cl

cis 4

(asymmetric C1)

enantiomers

same

trans 3


1 2

4

6

7

5

3

142




714

717

718

724

725

727

733

743

744

748

750

752

753

755

760

762

764

765

769

771

773

774

774

776

783

788

790

791

800

802

803

834

835

837

839

840

842

856

858

860

862

868

869

872

874

876

878

888

898

899

900

902

903

904

7273747576777879808182838485868788899091f1 (ppm)

143



144



145







intersecting waves

119894119894119890119890 = 04463119899119899119865119865119865119865119862119862 119899119899119865119865νD119877119877119877119877

12

Equation 1





146





-15 -18 -21 -24 -27-40

-20

0

20

40

60

80

Cur

rent

micro

A

Potential V vs Fc+0


147



A B

B

148


149


150


151

A

B

152







153


C D

154



A B

B

155


156



NN

NN

Re ReOC

COOCOC CO

O CO

O

NN

NN

Re ReClOC

COOCOC CO

Cl CO

NN

NN

Re ReOC

COOCOC CO

CO

+2e -2Cl__

NN

NN

Re ReOC

COOCOC CO

O CO

HO

NN

NN

Re ReOCOC

COOCOC CO

CO

+H+

H2O

+e_

CO

+

+CO2

+H+ e_

157


158


159


160



161


162


163



164


165


166


167


168


169


170


171


172


173



174


175



176


177




178




179


6971

7375

7779

8183

8587

8991

9395

9799

101f1 (ppm

)

201

214411395206

206

206

200

104

105

732732732733733733733734734756756757758759759767767768768768769769770770771774775775775775776776776777777782782782783784784797797797798798799827828861861861861861862862862862883980

NN

NN1

180

110115

120125

130135

140145

150155

160165

f1 (ppm)

11861

11996

1236112384124921255012691127381290612914

13155

137011378513798

14901

1545215489

15760

NN

NN1

181

7374

7576

7778

7980

8182

8384

8586

8788

8990

9192

93f1 (ppm

)

199

195

416

108

201

220192

192

200

096

200

753754760762

773773774776783788790791

834835837838840

868869876878

887

903904

NN

NN

ReRe

ClO

C

COO

CO

CCO

ClCO

cis -Re2 Cl2

182

DM

F

120125

130135

140145

150155

160165

170175

180185

190195

200205

f1 (ppm)

12404124941259312610126821283212848128711287713102131421315713190133411407714111

15410

1575715822

16187

1950719509

19947

NN

NN

ReRe

ClO

C

COO

CO

CCO

ClCO

cis -Re2 Cl2

183

7172

7374

7576

7778

7980

8182

8384

8586

8788

8990

9192

93f1 (ppm

)

088

098099106

198

328

099

088

300

107

088092

090095

084

092102

733743744748750752753755764765769771772774775781783784800802803

834835837840842843856858860862872873876878

887

897899900901

trans-Re2 Cl2

NN

N N

Re Re

OC

OC

OC

OC

Cl

Cl

OC

CO

184

105110

115120

125130

135140

145150

155160

165170

175180

185190

195200

205f1 (ppm

)

12392124391244212590126011261212667128511286112881129281303713057130921315013160131911332213331139591405914091141121413614180

154091542015706157601578315790162451624816315 DMF-d7

19096191951948419514

1988319936

DM

F

trans-Re2 Cl2

NN

N N

Re Re

OC

OC

OC

OC

Cl

Cl

OC

CO

185

6970

7172

7374

7576

7778

7980

8182

8384

8586

8788

8990

9192

9394

f1 (ppm)

202

112

108

102

103110108

107109104

098

097

100101096

747748749750753755756764766766767772774784786791792793793794795799801812814817818820823824840842

851853

872875876884

NN

2

186

114116

118120

122124

126128

130132

134136

138140

142144

146148

150152

154156

158160

162164

f1 (ppm)

1195712107124791248612550125691262612643127131277812826129061294112973131491319813216

137891383213887

14984

1554915582

15847

NN

2

187

APPENDIX B

188


(log ε)

120582120582119898119898119888119888119890119890119890119890119898119898 119899119899119899119899 λ1 λ2

ℎ120596120596 119888119888119899119899minus1

λ2



anthryl-Re 252 (480) 296 (415 366 (398)

570 688 764 1440

420 6 23

430 (1)

cis-Re2Cl2 258 (485) 296 (442) 380 (412)

592 700 776 1400

210 15 65

440 (1) 520 (1)

trans-Re2Cl2 258 (470) 296 (427) 376 (395)

598 698 772 1370

200 15 90

440 (1) 490 (095)


355 375

375 670 ---

6 3300 410 440


189


190

191

192





193





194


195

APPENDIX C

196



2 Structure DAP1


3 Structure DAP2

x y z N -116779101 -064002001 -108525395 C 068300301 075432998 -125431597 C -147904301 -010512900 018798700 C 148783505 028317201 -007852600

197

C 086488998 -000468100 110520506 C -060514897 007661000 123283005 H 006928100 161709297 -097713298 H 132201004 103113604 -208814597 H -254451108 -006943700 036536899 H 255957389 017099699 -017685100 H 144391096 -028888100 197464800 H -102901101 024935301 221440911 N -019210300 -032655400 -173923600

4 Structure NdisTS


5 Structure CdisTS


198

H -162471807 100128031 -085891795


7 Structure CconTS1


8 Structure NconInt

x y z N -117254436 -012935539 -103004634 C 114911330 052507800 -132641387 C -120073497 -078021890 027967709

199

C 134310114 -015687630 -002968836 C 069569921 037333986 107144785 C -048748320 -048004261 141496575 H 133888507 159884501 -131786120 H 169165754 009332362 -216674495 H -209250116 -139012527 032793716 H 135121119 -123951328 -009737577 H 064599955 144558704 123436141 H -081668174 -079587555 239674282 N -030165136 040838382 -168327153

9 Structure CconInt



x y z N -122473168 -045778599 -113910139 C 094505334 056573945 -136906683 C -131874728 -057033855 028926978 C 141338336 001856516 -006715097 C 073123562 049870428 117475450 C -057058573 -001180191 135865033 H 081215769 165091348 -134124863 H 163488150 034631550 -218331766 H -227999783 -100280988 053255856 H 165092111 -104281521 -007590441 H 117330158 121783650 185320687

200

H -107045138 005085879 231917119 N -035554022 002986831 -183606148



12 Structure DATCA


13 Structure DHDAP1

x y z

201


14 Structure DHDAP2



x y z N -142339540 -014606592 -116566598 C 093296069 025221679 -126147401 C -140808904 -032721406 022840041

202

C 119161737 -016610871 018556029 C 084130841 081545776 126951730 C -012877002 -034134027 101129293 H 080472010 133444512 -132227707 H 179706573 000164181 -187867403 H -235516500 -018690881 072857887 H 200624251 -086340731 035096633 H 139543521 092786473 219372249 H -011925846 -106822538 181810999 N -023407100 -035943642 -187034750 H -186182213 070168203 -147589076 H -010957908 -135344136 -195132947




x y z N -139562595 013293861 -109109366 C 099973285 019917566 -139172935 C -128806067 019103202 034260291 C 129041827 019030157 008237755 C 011506672 024624294 103696835 C -077405405 -098817056 111280930

203

H 101604879 123224723 -176587749 H 177840137 -033207700 -194385386 H -209643722 075877380 078947771 H 225147820 055132854 042733517 H 023269734 084052205 193693876 H -118028319 -148607981 198114049 N -027926472 -037997854 -177376115 H -158354163 104699314 -146162188 H -027862626 -137567961 -164485288




x y z N -143094933 000844477 -105635679 C 098796737 019592127 -131666112 C -139533913 -048966303 027399421 C 113849020 -002605952 017835093 C 054325736 089400637 112329757 C -024462490 -043452144 110718977 H 113207793 126165700 -151517606 H 175230050 -034002155 -188157892 H -231300664 -094758868 062348062

204

H 186804652 -073859274 054489440 H 004017371 175133789 067512351 H -011543095 -115248680 190509605 N -030366421 -020636971 -186336851 H -177593493 094211507 -117049420 H -029553342 -118461883 -208670139




x y z N -137007999 021642189 -103387082 C 101358879 009395494 -136566508 C -117764771 048460183 031954116 C 124384856 -023482305 009737201

C -016166560 -002143468 113447988 C 062831956 -134321129 076988173 H 116087043 116113365 -154630864 H 172647870 -044072470 -199733388 H -194308221 112372172 074224061 H 196049356 037644607 063625616 H -003499719 042012647 211345911 H 005090978 -197989404 009782664

205

N -032054877 -028873754 -181068313 H -182399678 097171456 -150863016 H -039848125 -128864574 -180960560





206





207





x y z N -150680757 056806660 -130433857

208

C 090254611 -013684431 -134248567 C -133901668 018480022 005263753 C 122509563 -068525136 007712884 C -045107952 076213592 092525667 C 066651374 -021551019 124015796 H 128556395 088743246 -137062228 H 151083350 -069635767 -205396152 H -155124116 -086979580 018505041 H 208378029 -134905469 012883927 H -018387491 181044579 081894964 H 104705095 -047549337 222000599 N -043426350 -010652254 -197062349 H -136226058 155375171 -143762600 H -075494838 -103908885 -215765285




x y z N -095442176 070564193 -090830022 C 109275067 -032066563 -159886014 C -129964244 034616992 040946886 C 153150833 -012862645 -017070051

209

C -051763374 -047516546 124236357 C 080180967 -090327680 089841759 H 152177787 045718437 -223145628 H 141152573 -128543031 -200184107 H -224236107 073953104 076580024 H 177199173 089397639 010826312 H -098024762 -082737643 215669823 H 125232351 -175105810 139811301 N -036664572 -028272822 -171884358 H -172617841 110976660 -139820719 H -073830664 -118157279 -145777547




x y z N -137026465 073302871 -128783345 C 087258899 -026980808 -142273438 C -154870033 032182592 005344129 C 116283774 -062507212 003527457 C -060129660 069691128 116412342 C 062601334 -001556111 119647968 H 141744506 066357487 -160980988

210

H 135420501 -101914442 -205298281 H -188953984 -070950902 010131884 H 209415388 -116732562 016407259 H -087284940 139373589 194623566 H 121124625 -005525590 210910273 N -046208549 -009558035 -198351347 H -105760002 168298090 -136993039 H -091536391 -098043090 -211986423

33 Structure TATCE


34 Structure TAP1


211




x y z N -130169976 019081797 -104405200 N 094327176 005109686 -123695779 C -121334004 030604666 032166755 C 123439634 -020356037 014254661 C 004350619 -000710853 108998549 C 064197320 -138673258 087150085 H 156055403 -038587660 -189167881 H -215111351 045885873 083115613

212

H 220896363 016127288 043982437 H 018502170 049485105 203912592 H 108914125 -205898929 158883250 N -030465758 003788886 -175479543







213










214







215

N3disTS2 -3176147485780 0093452 -3185162733931 -319109702140





216


217

APPENDIX D

218



2 Structure benzene



C -049969479 058574504 -058668292 C -009237672 -074989456 -045842883 C 103684449 -075878704 058275461 C -129300070 -015087587 053330708 C -082796496 -042341381 185065973 C 056331784 -064315730 185904157 H -101842010 096551085 -144943500 H -021508378 -155600154 -116254115

219

H 206526399 -074706024 028235289 H -233259010 -025569454 028742656 H -147755671 -048780558 269919682 H 117592144 -063192546 273840833



5 Structure conTS1a


6 Structure conTS1b

x y z C -050297093 057183838 -051857948 C 011780674 -068796760 -050674665 C 117886078 -091360807 057008582 C -138284039 -021255155 045741639 C -079290003 -026335379 172978771 C 064550996 -057442611 176313233 H 004066788 141775155 -013330726

220

H -024384066 -149950397 -110985982 H 214899445 -133708191 041018009 H -238862038 -051306462 023680490 H -137164462 -027439317 263406634 H 117979980 -062746698 269191432


C -060312861 033196312 -060104370 C 040970480 -069692659 -072337109 C 127138186 -078242040 051838052 C -151094031 008356415 058478689 C -086735332 -036093181 168573689 C 058521593 -064758307 167377901 H -028780583 135953712 -070557755 H 010424759 -165644002 -111363649 H 230138612 -108459997 049898896 H -254118514 038453919 060916448 H -139321041 -047924933 261498356 H 107564771 -078701591 261932731

8 Structure conInta


9 Structure conIntb

x y z C -051464897 034783122 -048861307 C 031462818 -074718034 -062273878 C 129794645 -076641470 054574531 C -154038537 005896322 060560381 C -087581515 -037048936 170687735 C 059228200 -064087760 169694412

221

H -002741032 130146420 -033919087 H -017220303 -170378208 -075352222 H 233453703 -104218507 052124327 H -257708979 033494130 061710888 H -139146316 -049250481 264236450 H 107345223 -077493781 264900017


C -009655527 046972793 -008906191 C -015227714 -094399583 -031827629 C 096095592 -041598082 063547862 C -123455715 -032644540 061718422 C -078297228 -057163441 201951647 C 046763608 -062262678 202995729 H -005597737 133870459 -071054584 H -017067322 -157307601 -118251884 H 198582458 -040685388 032961217 H -225004411 -023404928 029431415


C -085433865 007954445 -050540119 C 045567364 -051211542 -056695950 C 111552680 -095593274 057378685 C -153788245 023954958 072220904 C -077983809 -023981614 178692305 C 035904256 -075357455 172803020 H -131895959 040563443 -141686261 H 092737263 -060839272 -152674186 H 209028578 -139730299 053802228 H -251223373 067773306 078508759


C -057148534 064626724 -053885663 C -007987246 -074889797 -042853338 C 103785706 -090788382 059108502 C -131887484 -019899753 047291785 C -075266618 -029607776 183234119 C 048937288 -057841164 184531891 H -100361979 109947145 -140774906 H -018274766 -144842732 -123862195 H 207025957 -100489724 033048084

222


x y z C -048499542 057807237 -044684583 C -018107219 -087599397 -042789406 C 095849288 -077209949 049913400 C -131527638 -025317946 050453913 C -077220047 -035460770 189710152 C 045264027 -060662371 186098838 H 006353579 149203587 -037687969 H -026955703 -155766630 -125254023 H 198156440 -073115003 019051071 H -234816957 -039383724 025838998


C -056745547 058684391 -048268569 C 015725785 -068826091 -049418423 C 115661573 -093949485 059854102 C -141760385 -023299107 047563148 C -070996094 -020483841 169769883 C 057978088 -046565640 174749911 H -010151576 150768197 -018310136 H -005886872 -142647159 -124150288 H 202429724 -155759370 050416756 H -242468691 -054710895 029699609


C -059775037 062431282 -046530423 C -012702130 -081251937 -042224678 C 099712479 -090821701 054368252 C -132997572 -027527353 048931655 C -075663209 -031396541 187261868 C 046679676 -059068650 185656762 H -005315014 151507330 -022183387 H -022591665 -146724463 -126617146 H 202726650 -101349378 027691770 H -233505273 -056371480 025802734

223




benzvalyne





224



benzyne

MOs 15 16 17 18 19 20 21 21 23 24 25 26 disTSprime 1981 1969 1962 1908 1697 1236 0767 0303 0091 0041 0024 0020



225

226

VITA

WEIWEI YANG











227







ABSTRACT


ACKNOWLEDGEMENTS

LIST OF TABLES

LIST OF FIGURES

INTRODUCTION


11 Introduction












15 Conclusion


21 Introduction









232 Photocatalysis

233 Quantum yield

24 Conclusion


31 Introduction













35 Conclusion


41 Introduction



431 Benzvalene



432 Benzvalyne



44 Conclusion

CONCLUSION

BIBLIOGRAPHY

List of APPENDICES

APPENDIX A

APPENDIX B

APPENDIX C

APPENDIX D

VITA

v






TS transition state







ν scan rate







vi







T temperature



TON turnover number



MeOH methanol

PhOH phenol


PS photosensitizer


TEA triethylamine

φ quantum yield

vii








viii

ACKNOWLEDGEMENTS
















ix










x




LIST OF TABLES xiv

LIST OF FIGURES xv

INTRODUCTION 1



11 Introduction 7










xi



15 Conclusion 38



CHROMOPHORE 40

21 Introduction 40











24 Conclusion 55

xii




31 Introduction 57







35 Conclusion 93



41 Introduction 96



431 Benzvalene 99

432 Benzvalyne 106

44 Conclusion 111

xiii

CONCLUSION 113

BIBLIOGRAPHY 115

APPENDIX A 139

APPENDIX B 187

APPENDIX C 195

APPENDIX D 217

VITA 226

xiv

LIST OF TABLES


pH 7 vs NHE) 2















xv

LIST OF FIGURES











blue line 22








xvi










solutions 34





38



(2) 41


xvii












example above 55








xviii



66







74









xix



isomerization 85










isomerizations 92



100



xx








1

INTRODUCTION



















2

















3






















4












5











6


















conclusion44-46

7

CHAPTER I



11 Introduction














8









Cl ClO

O 1 Zn NH4OH (20) 80 oC 5 h

2 HCl iPrOH

Cl Cl

2 B B

Pd2(dba)3 + 4Xphos

dioxane 90 oC 2 d

B BO O O O

O

O O

O

N NBr


NN

NN

NN

NN

Re ReClOC

COOCOC CO

Cl CO

cis-Re2Cl2 1

Re(CO)5Cl

toluene ∆1 d

1a88

1b88

86

trans-Re2Cl2

N

N

N

N

Re

Re

OC

OC

OC

OCCl

Cl

OC

CO

+

41 20

9





















10





















11


electrode















CIF file




12




















13
















14901 13799 13785 13701 13155 12914 12906 12738 12691 12550 12492 12384






14








2H) 13C NMR (126 MHz DMF-d7) δ 19947 19509 19507 16187 15822 15757 15410

14111 14077 13341 13190 13157 13142 13102 12877 12871 12848 12832 12682








19936 19883 19514 19484 19195 19096 16248 16245 15790 15783 15760 15706

15420 15409 14180 14136 14112 14091 14059 13959 13331 13322 13191 13160

13150 13092 13057 13037 12928 12881 12861 12851 12667 12612 12601 12590



15












2H) 13C NMR (126 MHz DMSO-d6) δ 15847 15582 15549 14984 13887 13832 13789

13216 13198 13149 12973 12941 12906 12826 12778 12713 12643 12626 12569


3331







16




288 N 422


















17




1893 cm-1 in DMF16







days

74757677787980818283848586878889909192f1 (ppm)

199

195

416

108

201

220

192

192

200

096

200

7727374757677787980818283848586878889909192f1 (ppm)

088

098

099

106

198

328

099

088

300

107

088

092

090

095

084

092

102

A

B

18














19





















20





Figure A9)7980








N

NRe

OC

OCCl

CO

21



cis-Re2Cl2 -177 -187 -234 -265

KC = 50

trans-Re2Cl2 -178 -188 -240 -267

KC = 50

Re(bpy)(CO)3Cl -180 -225 - - D = 540 x 10-6 cm2 s-1

anthryl-Re -182 -229 -254 - D = 548 x 10-6 cm2 s-1











22




119894119894119888119888119888119888119888119888 = 119899119899119888119888119888119888119888119888119865119865119865119865[119888119888119888119888119888119888](119863119863119896119896119888119888119888119888119888119888[119878119878]119910119910)12 (1)

B

D

23













A B

24






Rate = minus[CO2]







B

25




















26








substrate5859

119879119879119879119879119865119865 = 119896119896119888119888119888119888119888119888[1198621198621198791198792] = 1198651198651198651198651198991198991199011199013

11987711987711987711987704463119899119899119888119888119888119888119888119888

21198941198941198881198881198881198881198881198881198941198941199011199012 (2)










119894119894119894119894119901119901

=224

119877119877119877119877119865119865119865119865119899119899119901119901

32119896119896119888119888119888119888119888119888[1198621198621198621198622]

1+119890119890119890119890119890119890 119865119865119877119877119877119877(119864119864minus1198641198641198881198881198881198881198881198882) (3)

27






















28












29





into account100

C

A B

D

30

119864119864 = 1198641198641198621198621198621198622119862119862119862119862(119863119863119863119863119865119865)0 minus 00592 ∙ 119901119901119901119901119888119888 (4)









TOF (s-1) eq 3

Ecat2

(120578120578)a Ecat2

(120578120578)b

cis-Re2Cl2 353 110 -229 (156)

-209 (092)

trans-Re2Cl2 229 44 -234 (161)

-195 (078)

Re(bpy)(CO)3Cl 111 15 -222 (149)

-204 (087)

anthryl-Re 192 41 -226 (153)

-218 (101)


0







31





















32





















33













B

cis-Re2Cl2

34











D

35






















36














+endash

-


37










38


15 Conclusion







NN

NN

Re ReOC

COOCOC CO

O CO

O

NN

NN

Re ReClOC

COOCOC CO

Cl CO

NN

NN

Re ReOC

COOCOC CO

CO

+2e -2Cl__

NN

NN

Re ReOC

COOCOC CO

O CO

HO

NN

NN

Re ReOCOC

COOCOC CO

CO

+H+

H2O

+e_

CO

+

+CO2

+H+ e_

39



















bond formation

40

CHAPTER II



21 Introduction










improved





41







Re2Cl2








N

N

N

N

Re

Re

OC

OC

OC

OCCl

OC

CO

HOO

NN

NN

Re Re0OC

COOCOC CO

Cl CON

NN

N

Re ReOC

COOCOC CO

O CO

O

N

N

N

N

Re

Re

OC

OC

OC

OCCl

CO

OC

CO

42


















such as BIH

43













44












and





NN

NN

Re ReClOC

COOCOC CO

Cl CON

N

N

N

Re

Re

OC

OC

OC

OCCl

Cl

OC

CO

N

NRe

OC

OCCl

CO

N

NRe

Cl

CO

CO

CO

45





















46






















47


















(1a)



48






















49





















50


232 Photocatalysis








51


















infra)

52
















53






















54

233 Quantum yield













55


24 Conclusion







56










57

CHAPTER III




31 Introduction







energy

58










59
















60













61









structure








62






















63

















64


















65


66








in Figure 25


67
















68
















transition state






69







energetics










70















71






bonded atoms









72






















73






















74












75













76




77



446 02

433 17

489 19









78









dihedral angle







79






















80








portion of the PES



81

















82






















83
















DHDAP products

84









85










86

















87














88
















89














transition state

90










activation barrier

91













92





93

35 Conclusion





















94






















95















the MRMP2 results

96

CHAPTER IV



41 Introduction















97






















98



















energy release

99


431 Benzvalene













100













101












102



















103














104












105





106

432 Benzvalyne







in Figure 48


107









108














109






















110








111




44 Conclusion
















112






kcal mol-1 barrier

113


















114




lone pair electrons









115

BIBLIOGRAPHY

116






305 (5682) 362ndash366






38 (1) 89ndash99





1399



117






7 (1) 70ndash88








536ndash538



1984 328ndash330




118





3387






2966ndash2974



Chem 2010 49 (20) 9283ndash9289








119








(5) 2966ndash2976



13993ndash13996




3214ndash3226



354ndash363




120




Soc 2015 137 (42) 13679ndash13690




3746ndash3754




10725







Am Chem Soc 2016 138 (6) 1938ndash1946



121






487ndash495






(10) 2931ndash2932



1988 110 (6) 1666ndash1671


Am Chem Soc 1995 117 (13) 3835ndash3847





122

Chem A 2009 113 (30) 8724ndash8730



Chem A 1999 103 (51) 11253ndash11256


















123





2003 125 (39) 11976ndash11987






5180ndash5186



7374ndash7376








124



6030



2012 41 (16) 5026ndash5037







14598ndash14607




138 (26) 8184ndash8193





125




Inorg Chem 2017 56 (7) 4176ndash4185



4593ndash4597



Madison WI 2000











2015 71 9ndash18

126




263ndash272




Trans 2012 41 (18) 5526ndash5541








2011 40 (10) 2225ndash2233






127


















1964 36 (4) 706ndash723



9983ndash10002

128



















(27) 11235ndash11242



129



8309ndash8318







2012 109 (39) 15646ndash15650



9329





463ndash469




130







(10) 2956ndash2962















131





7708






2012 41 (16) 5026ndash5037




14413ndash14424







132

1997 119 (45) 11012ndash11022



2001 105 (35) 8154ndash8161











2017 7 (1) 154ndash160




2013 135 (40) 15018ndash15025



133




2014 136 (48) 16768ndash16771








44 6311ndash6318



849ndash858



11806




134

135






Chem 2003 68 (23) 9081ndash9087







1358ndash1371




380




135


B01 2016





Chem A 2017 121 (46) 8899ndash8911




Soc 1975 97 (10) 2932ndash2933





1993 412 412ndash414



Soc 1998 120 (23) 5741ndash5750



136

(5) 1202ndash1204












Chem Phys 2012 14 (27) 9722ndash9728







1997 2 2761ndash2764


137









138

LIST OF APPENDICES

139

APPENDIX A

140


141

NN

NN

Re ReClOC

COOCOC CO

Cl CO

cis-Re2Cl2(CS

symmetric Cl-in)


1Cl-in 1Cl-out)

N

N

N

N

Re

Re

OC

OC

OC

OCCl

Cl

OC

CO

NN

NN

Re ReOCCl

COOCOC CO

CO Cl

cis 2


NN

NN

Re ReClCl

COOCOC CO

CO CO

cis 3

(asymmetric C1)

NN

NN

Re ReOCOC

COOCOC CO

Cl Cl

trans 2


N

N

N

N

Re

Re

OC

OC

OC

OCCl

CO

Cl

CO

N

N

N

N

Re

Re

OC

OC

OC

OCOC

Cl

OC

Cl

N

N

N

N

Re

Re

OC

OC

OC

OCOC

CO

Cl

Cl

cis 4

(asymmetric C1)

enantiomers

same

trans 3


1 2

4

6

7

5

3

142




714

717

718

724

725

727

733

743

744

748

750

752

753

755

760

762

764

765

769

771

773

774

774

776

783

788

790

791

800

802

803

834

835

837

839

840

842

856

858

860

862

868

869

872

874

876

878

888

898

899

900

902

903

904

7273747576777879808182838485868788899091f1 (ppm)

143



144



145







intersecting waves

119894119894119890119890 = 04463119899119899119865119865119865119865119862119862 119899119899119865119865νD119877119877119877119877

12

Equation 1





146





-15 -18 -21 -24 -27-40

-20

0

20

40

60

80

Cur

rent

micro

A

Potential V vs Fc+0


147



A B

B

148


149


150


151

A

B

152







153


C D

154



A B

B

155


156



NN

NN

Re ReOC

COOCOC CO

O CO

O

NN

NN

Re ReClOC

COOCOC CO

Cl CO

NN

NN

Re ReOC

COOCOC CO

CO

+2e -2Cl__

NN

NN

Re ReOC

COOCOC CO

O CO

HO

NN

NN

Re ReOCOC

COOCOC CO

CO

+H+

H2O

+e_

CO

+

+CO2

+H+ e_

157


158


159


160



161


162


163



164


165


166


167


168


169


170


171


172


173



174


175



176


177




178




179


6971

7375

7779

8183

8587

8991

9395

9799

101f1 (ppm

)

201

214411395206

206

206

200

104

105

732732732733733733733734734756756757758759759767767768768768769769770770771774775775775775776776776777777782782782783784784797797797798798799827828861861861861861862862862862883980

NN

NN1

180

110115

120125

130135

140145

150155

160165

f1 (ppm)

11861

11996

1236112384124921255012691127381290612914

13155

137011378513798

14901

1545215489

15760

NN

NN1

181

7374

7576

7778

7980

8182

8384

8586

8788

8990

9192

93f1 (ppm

)

199

195

416

108

201

220192

192

200

096

200

753754760762

773773774776783788790791

834835837838840

868869876878

887

903904

NN

NN

ReRe

ClO

C

COO

CO

CCO

ClCO

cis -Re2 Cl2

182

DM

F

120125

130135

140145

150155

160165

170175

180185

190195

200205

f1 (ppm)

12404124941259312610126821283212848128711287713102131421315713190133411407714111

15410

1575715822

16187

1950719509

19947

NN

NN

ReRe

ClO

C

COO

CO

CCO

ClCO

cis -Re2 Cl2

183

7172

7374

7576

7778

7980

8182

8384

8586

8788

8990

9192

93f1 (ppm

)

088

098099106

198

328

099

088

300

107

088092

090095

084

092102

733743744748750752753755764765769771772774775781783784800802803

834835837840842843856858860862872873876878

887

897899900901

trans-Re2 Cl2

NN

N N

Re Re

OC

OC

OC

OC

Cl

Cl

OC

CO

184

105110

115120

125130

135140

145150

155160

165170

175180

185190

195200

205f1 (ppm

)

12392124391244212590126011261212667128511286112881129281303713057130921315013160131911332213331139591405914091141121413614180

154091542015706157601578315790162451624816315 DMF-d7

19096191951948419514

1988319936

DM

F

trans-Re2 Cl2

NN

N N

Re Re

OC

OC

OC

OC

Cl

Cl

OC

CO

185

6970

7172

7374

7576

7778

7980

8182

8384

8586

8788

8990

9192

9394

f1 (ppm)

202

112

108

102

103110108

107109104

098

097

100101096

747748749750753755756764766766767772774784786791792793793794795799801812814817818820823824840842

851853

872875876884

NN

2

186

114116

118120

122124

126128

130132

134136

138140

142144

146148

150152

154156

158160

162164

f1 (ppm)

1195712107124791248612550125691262612643127131277812826129061294112973131491319813216

137891383213887

14984

1554915582

15847

NN

2

187

APPENDIX B

188


(log ε)

120582120582119898119898119888119888119890119890119890119890119898119898 119899119899119899119899 λ1 λ2

ℎ120596120596 119888119888119899119899minus1

λ2



anthryl-Re 252 (480) 296 (415 366 (398)

570 688 764 1440

420 6 23

430 (1)

cis-Re2Cl2 258 (485) 296 (442) 380 (412)

592 700 776 1400

210 15 65

440 (1) 520 (1)

trans-Re2Cl2 258 (470) 296 (427) 376 (395)

598 698 772 1370

200 15 90

440 (1) 490 (095)


355 375

375 670 ---

6 3300 410 440


189


190

191

192





193





194


195

APPENDIX C

196



2 Structure DAP1


3 Structure DAP2

x y z N -116779101 -064002001 -108525395 C 068300301 075432998 -125431597 C -147904301 -010512900 018798700 C 148783505 028317201 -007852600

197

C 086488998 -000468100 110520506 C -060514897 007661000 123283005 H 006928100 161709297 -097713298 H 132201004 103113604 -208814597 H -254451108 -006943700 036536899 H 255957389 017099699 -017685100 H 144391096 -028888100 197464800 H -102901101 024935301 221440911 N -019210300 -032655400 -173923600

4 Structure NdisTS


5 Structure CdisTS


198

H -162471807 100128031 -085891795


7 Structure CconTS1


8 Structure NconInt

x y z N -117254436 -012935539 -103004634 C 114911330 052507800 -132641387 C -120073497 -078021890 027967709

199

C 134310114 -015687630 -002968836 C 069569921 037333986 107144785 C -048748320 -048004261 141496575 H 133888507 159884501 -131786120 H 169165754 009332362 -216674495 H -209250116 -139012527 032793716 H 135121119 -123951328 -009737577 H 064599955 144558704 123436141 H -081668174 -079587555 239674282 N -030165136 040838382 -168327153

9 Structure CconInt



x y z N -122473168 -045778599 -113910139 C 094505334 056573945 -136906683 C -131874728 -057033855 028926978 C 141338336 001856516 -006715097 C 073123562 049870428 117475450 C -057058573 -001180191 135865033 H 081215769 165091348 -134124863 H 163488150 034631550 -218331766 H -227999783 -100280988 053255856 H 165092111 -104281521 -007590441 H 117330158 121783650 185320687

200

H -107045138 005085879 231917119 N -035554022 002986831 -183606148



12 Structure DATCA


13 Structure DHDAP1

x y z

201


14 Structure DHDAP2



x y z N -142339540 -014606592 -116566598 C 093296069 025221679 -126147401 C -140808904 -032721406 022840041

202

C 119161737 -016610871 018556029 C 084130841 081545776 126951730 C -012877002 -034134027 101129293 H 080472010 133444512 -132227707 H 179706573 000164181 -187867403 H -235516500 -018690881 072857887 H 200624251 -086340731 035096633 H 139543521 092786473 219372249 H -011925846 -106822538 181810999 N -023407100 -035943642 -187034750 H -186182213 070168203 -147589076 H -010957908 -135344136 -195132947




x y z N -139562595 013293861 -109109366 C 099973285 019917566 -139172935 C -128806067 019103202 034260291 C 129041827 019030157 008237755 C 011506672 024624294 103696835 C -077405405 -098817056 111280930

203

H 101604879 123224723 -176587749 H 177840137 -033207700 -194385386 H -209643722 075877380 078947771 H 225147820 055132854 042733517 H 023269734 084052205 193693876 H -118028319 -148607981 198114049 N -027926472 -037997854 -177376115 H -158354163 104699314 -146162188 H -027862626 -137567961 -164485288




x y z N -143094933 000844477 -105635679 C 098796737 019592127 -131666112 C -139533913 -048966303 027399421 C 113849020 -002605952 017835093 C 054325736 089400637 112329757 C -024462490 -043452144 110718977 H 113207793 126165700 -151517606 H 175230050 -034002155 -188157892 H -231300664 -094758868 062348062

204

H 186804652 -073859274 054489440 H 004017371 175133789 067512351 H -011543095 -115248680 190509605 N -030366421 -020636971 -186336851 H -177593493 094211507 -117049420 H -029553342 -118461883 -208670139




x y z N -137007999 021642189 -103387082 C 101358879 009395494 -136566508 C -117764771 048460183 031954116 C 124384856 -023482305 009737201

C -016166560 -002143468 113447988 C 062831956 -134321129 076988173 H 116087043 116113365 -154630864 H 172647870 -044072470 -199733388 H -194308221 112372172 074224061 H 196049356 037644607 063625616 H -003499719 042012647 211345911 H 005090978 -197989404 009782664

205

N -032054877 -028873754 -181068313 H -182399678 097171456 -150863016 H -039848125 -128864574 -180960560





206





207





x y z N -150680757 056806660 -130433857

208

C 090254611 -013684431 -134248567 C -133901668 018480022 005263753 C 122509563 -068525136 007712884 C -045107952 076213592 092525667 C 066651374 -021551019 124015796 H 128556395 088743246 -137062228 H 151083350 -069635767 -205396152 H -155124116 -086979580 018505041 H 208378029 -134905469 012883927 H -018387491 181044579 081894964 H 104705095 -047549337 222000599 N -043426350 -010652254 -197062349 H -136226058 155375171 -143762600 H -075494838 -103908885 -215765285




x y z N -095442176 070564193 -090830022 C 109275067 -032066563 -159886014 C -129964244 034616992 040946886 C 153150833 -012862645 -017070051

209

C -051763374 -047516546 124236357 C 080180967 -090327680 089841759 H 152177787 045718437 -223145628 H 141152573 -128543031 -200184107 H -224236107 073953104 076580024 H 177199173 089397639 010826312 H -098024762 -082737643 215669823 H 125232351 -175105810 139811301 N -036664572 -028272822 -171884358 H -172617841 110976660 -139820719 H -073830664 -118157279 -145777547




x y z N -137026465 073302871 -128783345 C 087258899 -026980808 -142273438 C -154870033 032182592 005344129 C 116283774 -062507212 003527457 C -060129660 069691128 116412342 C 062601334 -001556111 119647968 H 141744506 066357487 -160980988

210

H 135420501 -101914442 -205298281 H -188953984 -070950902 010131884 H 209415388 -116732562 016407259 H -087284940 139373589 194623566 H 121124625 -005525590 210910273 N -046208549 -009558035 -198351347 H -105760002 168298090 -136993039 H -091536391 -098043090 -211986423

33 Structure TATCE


34 Structure TAP1


211




x y z N -130169976 019081797 -104405200 N 094327176 005109686 -123695779 C -121334004 030604666 032166755 C 123439634 -020356037 014254661 C 004350619 -000710853 108998549 C 064197320 -138673258 087150085 H 156055403 -038587660 -189167881 H -215111351 045885873 083115613

212

H 220896363 016127288 043982437 H 018502170 049485105 203912592 H 108914125 -205898929 158883250 N -030465758 003788886 -175479543







213










214







215

N3disTS2 -3176147485780 0093452 -3185162733931 -319109702140





216


217

APPENDIX D

218



2 Structure benzene



C -049969479 058574504 -058668292 C -009237672 -074989456 -045842883 C 103684449 -075878704 058275461 C -129300070 -015087587 053330708 C -082796496 -042341381 185065973 C 056331784 -064315730 185904157 H -101842010 096551085 -144943500 H -021508378 -155600154 -116254115

219

H 206526399 -074706024 028235289 H -233259010 -025569454 028742656 H -147755671 -048780558 269919682 H 117592144 -063192546 273840833



5 Structure conTS1a


6 Structure conTS1b

x y z C -050297093 057183838 -051857948 C 011780674 -068796760 -050674665 C 117886078 -091360807 057008582 C -138284039 -021255155 045741639 C -079290003 -026335379 172978771 C 064550996 -057442611 176313233 H 004066788 141775155 -013330726

220

H -024384066 -149950397 -110985982 H 214899445 -133708191 041018009 H -238862038 -051306462 023680490 H -137164462 -027439317 263406634 H 117979980 -062746698 269191432


C -060312861 033196312 -060104370 C 040970480 -069692659 -072337109 C 127138186 -078242040 051838052 C -151094031 008356415 058478689 C -086735332 -036093181 168573689 C 058521593 -064758307 167377901 H -028780583 135953712 -070557755 H 010424759 -165644002 -111363649 H 230138612 -108459997 049898896 H -254118514 038453919 060916448 H -139321041 -047924933 261498356 H 107564771 -078701591 261932731

8 Structure conInta


9 Structure conIntb

x y z C -051464897 034783122 -048861307 C 031462818 -074718034 -062273878 C 129794645 -076641470 054574531 C -154038537 005896322 060560381 C -087581515 -037048936 170687735 C 059228200 -064087760 169694412

221

H -002741032 130146420 -033919087 H -017220303 -170378208 -075352222 H 233453703 -104218507 052124327 H -257708979 033494130 061710888 H -139146316 -049250481 264236450 H 107345223 -077493781 264900017


C -009655527 046972793 -008906191 C -015227714 -094399583 -031827629 C 096095592 -041598082 063547862 C -123455715 -032644540 061718422 C -078297228 -057163441 201951647 C 046763608 -062262678 202995729 H -005597737 133870459 -071054584 H -017067322 -157307601 -118251884 H 198582458 -040685388 032961217 H -225004411 -023404928 029431415


C -085433865 007954445 -050540119 C 045567364 -051211542 -056695950 C 111552680 -095593274 057378685 C -153788245 023954958 072220904 C -077983809 -023981614 178692305 C 035904256 -075357455 172803020 H -131895959 040563443 -141686261 H 092737263 -060839272 -152674186 H 209028578 -139730299 053802228 H -251223373 067773306 078508759


C -057148534 064626724 -053885663 C -007987246 -074889797 -042853338 C 103785706 -090788382 059108502 C -131887484 -019899753 047291785 C -075266618 -029607776 183234119 C 048937288 -057841164 184531891 H -100361979 109947145 -140774906 H -018274766 -144842732 -123862195 H 207025957 -100489724 033048084

222


x y z C -048499542 057807237 -044684583 C -018107219 -087599397 -042789406 C 095849288 -077209949 049913400 C -131527638 -025317946 050453913 C -077220047 -035460770 189710152 C 045264027 -060662371 186098838 H 006353579 149203587 -037687969 H -026955703 -155766630 -125254023 H 198156440 -073115003 019051071 H -234816957 -039383724 025838998


C -056745547 058684391 -048268569 C 015725785 -068826091 -049418423 C 115661573 -093949485 059854102 C -141760385 -023299107 047563148 C -070996094 -020483841 169769883 C 057978088 -046565640 174749911 H -010151576 150768197 -018310136 H -005886872 -142647159 -124150288 H 202429724 -155759370 050416756 H -242468691 -054710895 029699609


C -059775037 062431282 -046530423 C -012702130 -081251937 -042224678 C 099712479 -090821701 054368252 C -132997572 -027527353 048931655 C -075663209 -031396541 187261868 C 046679676 -059068650 185656762 H -005315014 151507330 -022183387 H -022591665 -146724463 -126617146 H 202726650 -101349378 027691770 H -233505273 -056371480 025802734

223




benzvalyne





224



benzyne

MOs 15 16 17 18 19 20 21 21 23 24 25 26 disTSprime 1981 1969 1962 1908 1697 1236 0767 0303 0091 0041 0024 0020



225

226

VITA

WEIWEI YANG











227







ABSTRACT


ACKNOWLEDGEMENTS

LIST OF TABLES

LIST OF FIGURES

INTRODUCTION


11 Introduction












15 Conclusion


21 Introduction









232 Photocatalysis

233 Quantum yield

24 Conclusion


31 Introduction













35 Conclusion


41 Introduction



431 Benzvalene



432 Benzvalyne



44 Conclusion

CONCLUSION

BIBLIOGRAPHY

List of APPENDICES

APPENDIX A

APPENDIX B

APPENDIX C

APPENDIX D

VITA

electro- and photocatalytic carbon dioxide reduction and

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