Found 16 Abstracts CONTROL ID: 1700986TITLE: Advances in the Bioinorganic Coordination Chemistry of CopperAUTHORS/INSTITUTIONS: W. Tolman, Department of Chemistry, University of Minnesota, Minneapolis, Minnesota,UNITED STATES|CURRENT CATEGORY: Bioinspired Coordination and Organometallic ChemistryABSTRACT BODY: Abstract Body: Inspired by the unusual active site structures and reactivities exhibited by copper enzymes, we seek toprepare and characterize synthetic complexes in order to test hypotheses developed to explain the novel functions ofthe biological sites. For example, mono and multicopper-oxygen species have been implicated as intermediates inenzymatic hydroxylation reactions, making them attractive targets for biomimetic synthetic studies. A survey of resultsof such studies will be described, with an emphasis on how ligand structural variation impacts the structures andproperties of the copper compounds that are prepared. Specific emphasis will be placed on efforts to synthesize andcharacterize complexes such as 1-3. The monocopper(III)-hydroxide cores in 1 and 2 may be viewed as protonatedversions of the elusive monocopper(II)-oxyl radical proposed to be involved in a variety of enzymatic and othercatalytic oxidation reactions. The oxo- and/or hydroxo-bridged dimetal units in 3 are targeted as models of keyproposed intermediates in multicopper active sites involved in substrate hydroxylations.

CONTROL ID: 1701063TITLE: A change in oxidation state of iron: scandium is not-innocentAUTHORS/INSTITUTIONS: M. Swart, Institut de Química Computacional i Catàlisi (IQCC) and Dept. de Química,Universitat de Girona, Girona, SPAIN|M. Swart, Institució Catalana de Recerca i Estudis Avançats (ICREA),Barcelona, SPAIN|CURRENT CATEGORY: Bioinspired Coordination and Organometallic ChemistryABSTRACT BODY: Abstract Body: In 2010, a new species {1} was reported[1], in which an iron-oxygen complex was capped by a Sc(3+)-moiety. This new species represents a series of complexes where a Lewis acid is binding to an metal-bound oxygenor nitrogen, and which may play a major role in the oxygen-evolving complex in photosystem II (interaction betweenCa(2+) and an oxomanganese species[2]), oxidation of water (Ce(4+) with an iron-oxo complex[3]), or stabilization ofvolatile species involving oxygen (Sc(3+) binding to an oxocobalt(IV) complex[4], the oxidation state of which isdisputed as well[5]) or nitrogen (Sc(3+) binding to Cu-nitrene[6]). The crystal structure of {1} showed a Fe-O distanceof 1.75 Å,[1] ca. 0.1 Å longer than typical iron(IV)-oxo Fe-O distances. This raised doubts about the oxidation state ofiron in the complex,[7] which could in principle be determined unequivocally by Mössbauer spectroscopy.Through extensive molecular modeling[8] of Fe(IV)-oxo, Fe(III)-oxo and Fe(III)-hydroxo complexes it is shown hereunambiguously that this assignment of the oxidation state should be revised. The oxidation state of iron in this Lewis-acid capped metal-bound oxygen system {1} is +3, coinciding with water as secondary axial ligand to scandium. Thespin state changes from intermediate spin (S=1) for typical Fe(IV)-oxo complexes to high spin (S=2) for the Sc(3+)-capped species.The implications for the Sc(3+) binding to an oxocobalt(IV) complex[4,5], and corresponding oxidation state of cobalt,has been studied as well.[1] Fukuzumi, Morimoto, Kotani, Naumov, Lee and Nam, Nature Chem, 2010, 2, 756 [2] Karlin, Nature Chem, 2010, 2,711 [3] Lloret Fillol, Codolà, Garcia-Bosch, Gómez, Pla and Costas, Nature Chem, 2011, 3, 807 [4] Pfaff, Kundu,Risch, Pandian, Heims, Pryjomska-Ray, Haack, Metzinger, Bill, Dau, Comba and Ray, Angew. Chem. Int. Ed., 2011,50, 1711 [5] Lacy, Park, Ziller, Yano and Borovik, J. Am. Chem. Soc., 2012, 134, 17526[6] Kundu, Miceli, Farquhar, Pfaff, Kuhlmann, Hildebrandt, Braun, Greco and Ray, J. Am. Chem. Soc., 2012, 134,14710 [7] McDonald and Que Jr., Coord. Chem. Rev., 2013, 257, 414 [8] Swart, Chem Comm 2013, on line, DOI10.1039/C3CC42200C

CONTROL ID: 1701210TITLE: Nitric Oxide Derivatives of Natural Porphyrins (Hemes)AUTHORS/INSTITUTIONS: W.R. Scheidt, J.W. Pavlik, N.J. Silvernail, G.R. Wyllie, Q. Peng, A.G. Oliver, Departmentof Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, UNITED STATES|A.Barabanschikov, J.T. Sage, Department of Physics, Northeastern University , Boston, Massachusetts, UNITEDSTATES|CURRENT CATEGORY: Bioinspired Coordination and Organometallic ChemistryABSTRACT BODY: Abstract Body: Recent studies of NO derivatives of the trio of naturally occurring hemes will be reported. Includedin the study is a structure determination of [Fe(PPIXDME)(NO)] (PPIXDME is protoporphyrin IX dimethylester), whichreveals the generally asymmetric features in the equatorial plane, but also a disordered axial NO. Similarities in theintermolecular interactions with the previously reported structure of [Fe(DPIXDME)(NO)] (DPIXDME isdeuteroporphyrin IX dimethylester) will be noted. The vibrational dynamics of all three naturally occurring heme NOswill be reported. Detailed nuclear resonance vibrational spectroscopic (NRVS) studies of [Fe(DPIXDME)(NO)]includes a study of the in-plane vibrational anisotropy. The effects of the FeNO orientation and the peripheralsubstituents on the in-plane iron motion will be discussed. Both have effects on the direction of the in-plane ironmotion that are in opposition to directions expected from the in-plane bonding.

In-plane vibrational anisotropy for [Fe(DPIXDME)(NO)] (DP is deuteroporphyrin IX)

CONTROL ID: 1701509TITLE: Resolving the Roles of Dissimilar Irons in a Proton Reduction Electrocatalyst: [(NO)Fe(N2S2)Fe(NO)2]+ andIts Reduced AnalogueAUTHORS/INSTITUTIONS: M.Y. Darensbourg, C. Hsieh, A.M. Lunsford, S. Ding, J.H. Reibenspies, M.B. Hall,Chemistry, Texas A&M University, College Station, Texas, UNITED STATES|CURRENT CATEGORY: Bioinspired Coordination and Organometallic ChemistryABSTRACT BODY: Abstract Body: Despite the advances in synthesis and mechanistic insight that the H2ase-inspired, base-metalcatalysts have provided in the past decade, a systematic development that draws on the expected necessary featuresto improve performance has not produced highly active and robust molecular assemblies. Arguably the bestmolecular electrocatalyst for hydrogen processing that has resulted from the hydrogenase active site inspiration is amononuclear nickel complex with a built-in pendant nitrogen base—but with no diatomic ligands or proximal metal, theDuBois catalyst. Other monometallic H2-evolving catalysts, with or without pendant bases, have also been reported.Nevertheless the ubiquity of bimetallic active sites in biology provides a compelling argument for investigation offeatures that inform on the contributions of individual metals to the overall catalytic processes. Accordingly, we haveexamined a non-carbonyl diiron complex with an obvious irondithiolate as bidentate ligand to a second iron, adinitrosyl iron moiety. Both the N2S2Fe(NO) metallo-ligand and the Fe(NO)2 unit can exist in two redox levels,observable by reversible waves in the cyclic voltammogram assignable to distinct components, each of which canshow electrocatalytic response to acid. Molecular structures of the diiron trinitrosyl compound in oxidized and one-electron reduced forms demonstrate the accommodation of redox level changes in such bimetallic molecules thatinvolves the electronically versatile NO ligand. Comparisons to the familiar [FeFe]- and [NiFe]-Hydrogenasebiomimetics based on iron carbonyls expand the possible base-metal electrocatalysts into the non-innocence of iron-nitrosyl chemistry.

CONTROL ID: 1704581TITLE: The first Functional Model System for Flavodiiron Nitric Oxide ReductasesAUTHORS/INSTITUTIONS: N. Lehnert, S. Zheng, T. Berto, A. Speelman, Department of Chemistry, University ofMichigan, Ann Arbor, Michigan, UNITED STATES|CURRENT CATEGORY: Bioinspired Coordination and Organometallic ChemistryABSTRACT BODY: Abstract Body: Nitric oxide (NO) is produced by macrophages as a key immune defense agent to kill invadingpathogens. For this purpose, inducible NO synthase produces up to μM concentrations of NO, which is toxic againstmicrobes. However, recent research has shown that some pathogens (e.g., Helicobacter pylori, Neisseriameningitides, Trichomonas vaginalis, Salmonella enterica) have evolved defenses against NO toxicity by expressingflavodiiron NO reductases (FNORs) that are able to efficiently remove NO by reduction to non-toxic N2O.[1] Thisdefense mechanism allows these pathogens to proliferate in the human body, causing harmful infections. FNORstherefore constitute significant targets for drug development. Despite their significance for microbial pathogenesis, themechanism of these enzymes is not well understood.In this contribution, the synthesis and spectroscopic characterization of the diiron dinitrosyl model complex[Fe2(BPMP)(OPr)(NO)2](BPh4)2 is presented.[2] The crystal structure of this complex shows two end-on coordinated{FeNO}7 units, which are geometrically distinct with Fe-N(O) distances of 1.774 Å and 1.796 Å and Fe-N-O angles of155.5° and 144.7°, respectively. This is due to a non-symmetric coordination of the BPMP ligand. Based onspectroscopic and electrochemical results, the two {FeNO]7 units are only weakly electronically coupled in thiscomplex. Importantly, reduction of this complex by two electrons leads to the clean formation of N2O in quantitativeyield. This complex therefore represents the first example of a functional model system for FNORs. These resultsprovide key mechanistic insight into the mechanism of FNORs, and in particular, represent strong support for theproposed “super-reduced” mechanism for these enzymes. In contrast, analogous mononuclear {FeNO}7 complexesdo not catalyze N2O formation after one-electron reduction. The underlying reasons for this finding are furtherdiscussed. References:[1] Kurtz, D. M., Jr., J. Chem. Soc. Dalton Trans. 2007, 4115[2] Zheng, S.; Berto, T. C., Dahl, E. W.; Hoffman, M. B.; Speelman, A. L.; Lehnert, N., J. Am. Chem. Soc. 2013, 135,asap

CONTROL ID: 1708374TITLE: Electrochemical O2 reduction in presence of a Mn(II) complex. Formation and reactivity of a Mn(III)OOcomplexAUTHORS/INSTITUTIONS: E. Anxolabehere-Mallart, V.H. Ching, C. Costentin, M. Robert, Laboratoired'Electrochimie Moléculaire UMR CNRS - P7 7591, Université Paris Diderot - Paris 7, Paris, FRANCE|V.H. Ching, C.Policar, Laboratoire des BioMolécules, UMR CNRS 7203 , Département de Chimie, Université Pierre et Marie Curie-Paris 6, Ecole Normale Supérieure, Paris, FRANCE|P. Dorlet, Laboratoire Stress Oxydant et Détoxication, UMRCNRS 8221 , CEA-Université Paris 11, Saclay, FRANCE|CURRENT CATEGORY: Bioinspired Coordination and Organometallic ChemistryABSTRACT BODY: Abstract Body: Mn(III)(hydro)peroxo species have been suggested to be key intermediates in enzymatic cycles of Mn-containing enzymes (MnSOD, catalase, OEC of PSII). It is thus of great interest to prepare and characterizeMn(III)(hydro)peroxo model complexes that will help understanding the reaction mechanisms involved at the activesite of these metalloproteins. We and others have reported examples of chemically4 or electrochemically5 preparedMn(III)(hydro)peroxo complexes.Herein we report on the preparation and reactivity of a novel monomeric LMn(III)OO adduct. Formation of LMn(III)OOresults from reaction of electrochemically reduced O2 and a LMn(II) complex ((scheme 1) according to reaction (1).The electrochemical formation of LMn(III)OO is monitored in DMF by cyclic voltammetry, low temperature UV-visabsorption spectroscopy and EPR spectroscopy. [Mn(II)L]+ + O2

●− → [Mn(III)L(OO)] (reaction 1, k)

Analysis of experimental data reveal that:(i) kinetics of reaction 1 is controlled by diffusion (k ≈ 1010 M-1s-1)(ii) upon addition of a strong acid (HClO4), the Mn-O bond is broken resulting in the release of H2O2 according to[LMn(III)OO] + 2H+→ [LMn(III)] + H2O2 (iii) in presence of a weak acid (H2O), [LMn(III)OO] is reduced through a 2-electron process, kinetically controlled bythe first electron transfer. We propose that the O-O bond is broken according to [LMn(III)OO] + 2e- + 2H+→[LMn(III)(OH)2] The present work is the first example of an electrochemical study of [LMn(III)OO] species in organic medium withcontrolled proton content. 1 (a)Groni S., Blain G., Guillot R., Policar C., Anxolabéhère-Mallart E., Inorg. Chem. 2007, 46, 1951-1953; (b)Groni S.,Dorlet P., Blain G., Bourcier S., Guillot R., Anxolabéhère-Mallart E., Inorg. Chem. 2008, 47, 3166-3172; (c)Geiger R.A., Leto D. F., Chattopadhyay S., Dorlet P., Anxolabéhère-Mallart E., Jackson T. A., Inorg. Chem., 2011, 50, 10190-10203 and ref. herein 2 El Ghachtouli S., Ching H. Y. V., Lassalle-Kaiser B., Guillot R., Leto D. F., Chattopadhyay S., Jackson T. A., DorletP., Anxolabéhère-Mallart E., Chem. Commun., 2013, under revision

Scheme 1: [Mn^IIL]⁺ (Sol = DMF)

CONTROL ID: 1709279TITLE: End-on nickel(II)-superoxo and side-on nickel(III)-peroxo complexes bearing a common macrocyclic ligandAUTHORS/INSTITUTIONS: J. Cho, Emerging Materials Science, DGIST, Daegu, KOREA, REPUBLIC OF|W. Nam,Bioinspired Science, Ewha Womans University, Seoul, KOREA, REPUBLIC OF|CURRENT CATEGORY: Bioinspired Coordination and Organometallic ChemistryABSTRACT BODY: Abstract Body: Mononuclear metal-dioxygen adducts, such as metal-superoxo and -peroxo species, are generated askey intermediates in the catalytic cycles of dioxygen activation by heme and non-heme metalloenzymes. We haveshown recently that the geometric and electronic structure of the Ni-O2 core in [Ni(O2)(n-TMC)]+ (n = 12 and 14)varies depending on the ring size of the supporting TMC ligands. In this study, mononuclear Ni(II)-superoxo andNi(III)-peroxo complexes bearing a common macrocylic TMC ligand, such as [NiII(O2)(13-TMC)]+ and [NiIII(O2)(13-TMC)]+, were synthesized in the reactions of [NiII(13-TMC)(CH3CN)]2+ and H2O2 in the presence oftetramethylammonium hydroxide (TMAH) and triethylamine (TEA), respectively. The Ni(II)-superoxo and Ni(III)-peroxocomplexes bearing the common 13-TMC ligand were successfully characterized by various spectroscopic methods, X-ray crystallography, and DFT calculations. Based on the combined experimental and theoretical studies, we concludethat the superoxo ligand in [NiII(13-TMC)(O2)]+ is bound in an end-on fashion to the nickel(II) center, whereas theperoxo ligand in [NiIII(13-TMC)(O2)]+ is bound in a side-on fashion to the nickel(III) center. Reactivity studiesperformed with the Ni(II)-superoxo and Ni(III)-peroxo complexes toward organic substrates reveal that the formerpossesses an electrophilic character, whereas the latter is an active oxidant in nucleophilic reaction.

CONTROL ID: 1711460TITLE: High-spin iron-hydride and iron-dinitrogen complexes of relevance to the function of nitrogenasesAUTHORS/INSTITUTIONS: P.L. Holland, Department of Chemistry, Yale University, New Haven, Connecticut,UNITED STATES|CURRENT CATEGORY: Bioinspired Coordination and Organometallic ChemistryABSTRACT BODY: Abstract Body: Nitrogenase enzymes perform the biological reduction of dinitrogen to ammonia, and spectroscopicstudies have shown that iron-hydride and iron-dinitrogen intermediates are important intermediates in the mechanism.In order to substantiate these ideas, we have prepared Fe-H and Fe-N2 coordination compounds with with a weak-field coordination environment that is reminiscent of the iron environment in the active site of nitrogenase. We havebeen able to isolate high-spin iron(II) and iron(I) hydride complexes, as well as iron(I) dinitrogen complexes that cleaveN-N bonds. Systematic spectroscopic studies using X-ray absorption and emission techniques, EPR, Mössbauer, andENDOR spectroscopies elucidate the characteristic signatures of these species, and mechanistic studies show theparticularly high reactivity of compounds in which multiple iron atoms can cooperate to activate a small molecule.(No Image Selected)

CONTROL ID: 1714405TITLE: High-Frequency and -Field EPR Spectroscopy of Iron(IV)AUTHORS/INSTITUTIONS: J. Krzystek, A. Ozarowski, National High Magnetic Field Laboratory, Tallahassee, Florida,UNITED STATES|J. Telser, Roosevelt University, Chicago, Illinois, UNITED STATES|J. England, G.T. Rohde, L. Que,University of Minnesota, Minneapolis, Minnesota, UNITED STATES|I. Nieto, R.P. Bontchev, J.M. Smith, New MexicoState University, Las Cruces, New Mexico, UNITED STATES|R.P. Bontchev, Cabot Micro Powders, Albuquerque,New Mexico, UNITED STATES|T.J. Collins, Carnegie Mellon University, Pittsburgh, Pennsylvania, UNITED STATES|CURRENT CATEGORY: Bioinspired Coordination and Organometallic ChemistryABSTRACT BODY: Abstract Body: High-valent states of iron, namely Fe(IV) to Fe(V) have been implicated in a variety of biocatalyticreactions including activation of dioxygen. Of these iron forms, iron(IV) is more accessible experimentally, yet it tooksignificant effort to synthesize stable biomimetic Fe(IV) coordination complexes. EPR spectroscopists have been interested in the Fe(IV) ion because of its 3d4 electron configuration, which results ineither a high-spin (S = 2) or intermediate-spin (S = 1) form, both non-Kramers (integer spin number) systems. Thehigh-spin species is present in metalloenzymes while synthetic models have until recently afforded the intermediate-spin form. The presence of large zero-field splitting in both spin states makes them not amenable to conventionalEPR, and necessitates an application of high frequencies and magnetic fields (HFEPR), which has been the mainmotivation behind this work. Some of us have previously reported on a successful HFEPR investigation of two iron(IV) oxo complexes [1]characterized by an intermediate spin state: [FeO(TMC)(CH3CN)](OTf)2, where TMC is tetramethylcyclam and OTf =CF3SO3-, and [FeO(N4py)](OTf)2, where N4Py is bis(2-pyridylmethyl)bis(2-pyridyl)methylamine. In the current work,we will present HFEPR results on further examples of S = 1 Fe(IV) species: imides such as LMesFe≡NAd whereLMes is phenyltris(1-mesitylimidazol-2-ylidene)borate) [2], and complexes with TAML® activators [3]. We will alsopresent HFEPR results on a novel complex [FeIV(O)(TMG3tren)](OTf)2, where TMG3tren is 1,1,1-tris{2-[N2-(1,1,3,3-tetramethylguanidino)]ethyl}amine), which is unusually characterized by an S = 2 state [4]. We will discuss theapplicability of HFEPR to investigate Fe(IV) complexes, and the information on electronic structure that could beultimately obtained, in conjunction with other experimental methods. [1] Krzystek, J., et al., Inorg. Chem., 2008, 47, 3843.[2] Nieto, I., et al., J. Am. Chem. Soc., 2008, 130, 2716.[3] Kundu, S., et al., Chem. Eur. J., 2012, 18, 10244.[4] England, J., et al., J. Am. Chem Soc., 2010, 132, 8635.

Figure 1. 2-dimensional field/frequency map of turning points in the frozen CH2Cl2 solution EPR spectra of[Fe(O)(TMG3tren)]2+. Squares are experimental data, lines were calculated using best-fitted spin Hamiltonianparameters: S = 2, D = 4.95 cm–1, |E| = 0, B40 = -13x10-4 cm-1, B42 = -9x10-4 cm-1, B44 = +3x10-4 cm-1, g⊥ =2.004, g|| = 2.04.

CONTROL ID: 1714648TITLE: Mononuclear Copper Active Oxygen Complexes Relevant to the Reactive Intermediate Involved in CopperMonooxygenasesAUTHORS/INSTITUTIONS: S. Itoh, Y. Kobayashi, T. Tano, S. Paria, H. Sugimoto, N. Fujieda, Material and LifeScience, Osaka University, Suita, Osaka, JAPAN|CURRENT CATEGORY: Bioinspired Coordination and Organometallic ChemistryABSTRACT BODY: Abstract Body: Mononuclear copper(II) active-oxygen species such as superoxide and oxide have been invoked as akey reactive intermediate involved in the catalytic reactions of copper monooxygenases such as peptidylglycine α-hydroxylating monooxygenase (PHM) and dopamine β-monooxygenase (DβM). These enzymes catalyze thehydroxylation reaction of aliphatic substrates by molecular oxygen at a simple mononuclear copper reaction center. Agreat deal of efforts has so far been made in model studies to provide important insights into the structure andreactivity of the mononuclear active-oxygen species. In this study, we have examined the reactions of copper(I)complexes supported by sterically demanding tetradentate ligands (tren derivatives) toward molecular oxygen andalkyl hydroperoxides to find formation of mononuclear copper(II)-superoxide and copper(II)-oxide like complexes,respectively. Spectroscopic characteristics as well as the reactivity of these active-oxygen complexes have beenexamined in order to get further insights into the mechanism of the enzymatic reactions. (No Image Selected)

CONTROL ID: 1715872TITLE: Dinitrogen Functionalization with Organometallic and Redox-Active Transition Metal Complexes.AUTHORS/INSTITUTIONS: P.J. Chirik, Chemistry, Princeton, Princeton, New Jersey, UNITED STATES|CURRENT CATEGORY: Bioinspired Coordination and Organometallic ChemistryABSTRACT BODY: Abstract Body: The functionalization of elemental nitrogen (N2) to ammonia and other value-added nitrogen-containing organic molecules is one of the longest standing challenges in chemical synthesis. The venerable Haber-Bosch industrial ammonia synthesis has changed life on our planet supporting approximately 50% of the world’spopulation and serving as the source of 40-60% of the nitrogen in the human body. The fossil fuel inputs principallyfrom methane steam reforming to produce dihydrogen couples food prices and to natural resource markets. Althoughnitrogenase enzymes fix N2 to ammonia at atmospheric pressure and ambient temperature, the large overpotentialassociated with NH3 synthesis renders the process less energy efficient than the Haber-Bosch route. Therefore,chemical methods that circumvent ammonia synthesis and directly assemble organic molecules from molecularnitrogen are an attractive proposition. Our laboratory has discovered a family of zirconium and hafnium dinitrogencomplexes that undergo N-N scission and assembly of N-C bonds upon addition of carbon monoxide. My lecture willfocus on the scope, mechanism and versatility of this transformation as well as present new routes into the synthesisof activated metal dinitrogen compounds. Strategies for transfer of the functionalized nitrogen ligands into existingcatalytic chemistry will also be discussed.(No Image Selected)

CONTROL ID: 1716472TITLE: Biomimetic Radical Chemistry of Iron and Copper:Hemes, Iron-Sulfur Clusters, and AlkoxidesAUTHORS/INSTITUTIONS: J.M. Mayer, T.R. Porter, C.T. Saouma, J.J. Warren, D. Capitao, M. Pinney, Chemistry,University of Washington, Seattle, Washington, UNITED STATES|J.J. Warren, Chemistry, California Institute ofTechnology, Pasadena, California, UNITED STATES|CURRENT CATEGORY: Bioinspired Coordination and Organometallic ChemistryABSTRACT BODY: Abstract Body: Iron and copper centers typically undergo one-electron redox changes while mediating biochemicalprocesses. Presented here will be new reactions in which Fe or Cu redox change is coupled to bond-making/bond-breaking, including metal–oxygen bonds and oxygen-hydrogen or sulfur-hydrogen bonds in a ligand. Iron-porphyrin complexes with pendant acid/base sites undergo proton-coupled electron transfer/hydrogen atomtransfer. Examples include Fe(III)-imidazolate species, protoporphyrin(IX) compounds where the proton binds to aheme propionate, and a porphyrin-meso-phenylbenzoate derivative with a 14 Å separation between the iron and thetransferring proton. In a related system, the iron(III) hydroxide compound (TMP)Fe(OH), a model for a common restingstate of heme proteins, also abstracts H atoms from weak O–H bonds such as in the hydroxylamine TEMPO–H ordiphenylhydrazine. The product (TMP)Fe(II) reversibly binds the TEMPO radical, with Keq = 520 ± 25 M-1 and with adissociation rate that is fast on the NMR timescale. Other H-atom transfer reactions and the catalyticdisproportionation of TEMPO-H will also be discussed. Hydrogen atom transfers to TEMPO and to the 2,4,6-tri-t-butyl-phenoxyl radical also have been observed fromreduced and protonated iron-sulfur clusters. A model for reactions of Rieske Fe2S2 clusters, with imidazolate ligands,will be presented. Related chemistry of Fe4S4(SR)4 clusters will be discussed, as well the challenges of working withFe/S clusters in the presence of protons. Unusual copper(II)-alkoxide complexes have been generated using the bulky hydro-trispyrazolylborate ligands Tp/ i >Bu – and TpMe , tBu–. Complexes of simple alkoxides with α hydrogens, such as ethoxide compounds, are unstableto reduction to Cu(I). Examples with the fluoro-alkoxides TpRCuIIOCH2CF3 and TpRCuIIOCH(CF3)2 will bepresented. These species are surprisingly strong H-atom acceptors, and these proton-coupled electron transferreactions are coupled to Cu–O bond cleavage. The reactions of Cu-alkoxide species with oxyl radicals are related tothe proposed key step in the catalytic cycle of galactose oxidase.(No Image Selected)

CONTROL ID: 1716877TITLE: Dinitrogen Hydrogenationon an Isolated Surface Tantalum Atom,Mechanistic Relevance of Dihydrogenand Relationship to NitrogenaseAUTHORS/INSTITUTIONS: E.A. Quadrelli, CPE Lyon, CNRS Université de lyon, Villeurbanne, Rhone Alpes,FRANCE|CURRENT CATEGORY: Bioinspired Coordination and Organometallic ChemistryABSTRACT BODY: Abstract Body: Université de Lyon, ICL, UMR 5265 C2P2 CNRS- Université Lyon 1- CPE-Lyon, LCOMS, 43 Blvd du 11 Novembre1918, BP 2077 69616, Villeurbanne, France. quadrelli@cpe.fr A draft mechanism for nitrogenase catalytic conversion of N2 to ammonia is now available, assigning a crucial role tobridging iron-hydride bonds to start N2 reduction on the FeMo cofactor: two metal-hydride bonds function, one mightsay, as an intermediary “electron storage” device; the two electrons which are necessary for the first reduction of N2 todiazenido becoming available upon H2 release. [1] We have reported an heterogeneous system based on silica-supported tantalum hydrides capable of achievingdinitrogen cleavage with dihydrogen [2] for which we have uncovered a molecular mechanism that entails the samemechanistic feature. [3] This presentation will detail our studies leading to the proposed mechanism (thereincluded reaction hydrazido anddiazenido intermediates revealed by in situ IR monitoring of the reaction as well as the connected DFT studies [3]and catalytic H/D exchanges studies on final imido complexe[4]) and attempt to compare and contrast our mechanismwith the current proposal in nitrogenase to highlight the role of dihydrogen in dinitrogen cleavage and hydrogenation. ____[1]. Hoffman, Brian M.; Lukoyanov, Dmitriy; Dean, Dennis R.; Seefeldt, Lance C. Accounts of Chemical Research(2013), 46(2), 587-595. [2] P. Avenier, M. Taoufik, A. Lesage, X. Solans-Monfort, A. Baudouin, A. de Mallmann, L. Veyre, J.-M. Basset, O.Eisenstein, L. Emsley, E. A. Quadrelli Science 317, 1056-1060 (2007).[3] Solans-Monfort, Xavier; Chow, Catherine; Goure, Eric; Kaya, Yasemin; Basset, Jean-Marie; Taoufik, Mostafa;Quadrelli, Elsje Alessandra; Eisenstein, Odile Inorganic Chemistry (2012), 51(13), 7237-7249[4] Chow, Catherine; Taoufik, Mostafa; Quadrelli, Elsje Alessandra European Journal of Inorganic Chemistry (2011),(9), 1349-1359.

CONTROL ID: 1720714TITLE: Peroxynitrite Intermediates in Heme / Dioxygen / NO ChemistryAUTHORS/INSTITUTIONS: S.K. Sharma, Chemistry, Johns Hopkins University, Baltimore, Maryland, UNITEDSTATES|Y. Li, Chemistry, Johns Hopkins University, Baltimore, Maryland, UNITED STATES|M.P. Schopfer,Chemistry, Johns Hopkins University, Baltimore, Maryland, UNITED STATES|K.D. Karlin, chemistry, Johns HopkinsUniversity, Baltimore, Maryland, UNITED STATES|CURRENT CATEGORY: Bioinspired Coordination and Organometallic ChemistryABSTRACT BODY: Abstract Body: Our research aims to contribute to a fundamental understanding of the interactions of molecularoxygen and nitrogen oxides with iron centers via the examination of synthetically derived model systems. Heme / dioxygen / nitric oxide biochemistry and the formation of peroxynitrite (O=NOO–), an exceptionally strongoxidizing and nitrating agent, is of considerable biological interest. There exists a variety of sources of NO(g)production in vivo, and certain bacterial and mammalian enzymes possess nitric oxide dioxygenase (NOD) activity,the ability to catalyze the reaction of NO(g) and Dioxygen to yield the more biologically benign nitrate. Heme-peroxynitrite intermediates have been invoked in this process. The reaction of dioxygen (O2) with [(F8)Fe(II)],{F8 =tetrakis(2,6-difluorophenyl)porphyrinate(2–)} leads to the formation of the heme-superoxo complex [(F8)Fe(III)-(O2–)],and further reaction with NO(g) leads to a heme-nitrate complex, [(F8)Fe(III)-(NO3–)]. Chemical evidence for aproposed peroxynitrite or peroxynitrite-type intermediate is suggested from the observation of nitration/oxidationreactions of added phenolic substrates. A variety of other reactions are being studied to provide further insights intothe chemistry observed. These include (i) the reaction of a heme dinitrosyl complex, [(F8)Fe(II)(NO)2], with dioxygenand (ii) by variation in the nature of the porphyrin as in superoxides of [(PIm)Fe(III)(O2–)], [(PPy)Fe(III)(O2–)]{PIm/PPy = Porphyrin with chelated axial imidazole/Pyridine ‘base’} and its reaction with NO (g) which leads to theformation of metastable species at low temperature, that which is believed to be a “low spin peroxynitrite-heme”complex, based on chemical and spectroscopic evidence to be presented. References1.Schopfer, M. P.; Mondal, B.; Lee, D.-H.; Sarjeant, A. A. N.; Karlin, K. D. J. Am. Chem. Soc. 2009, 131, 11304-11305.2. Wang, J.; Schopfer, M. P.; Sarjeant, A. A. N.; Karlin, K. D. J. Am. Chem. Soc. 2009, 131, 450-451.3. Li, Yuqi; Sharma, S. K.; Karlin, K. D. Polyhedron, 2013, in press, http://dx.doi.org/10.1016/-j.poly.2012.11.011.

CONTROL ID: 1721576TITLE: C-H bond activation of alkanes and C-N bond cleavage of anilines by a ruthenium(VI) nitrido complexAUTHORS/INSTITUTIONS: T. Lau, Biology and Chemistry, City University of Hong Kong, Kowloon Tong, HONGKONG|CURRENT CATEGORY: Bioinspired Coordination and Organometallic ChemistryABSTRACT BODY: Abstract Body: The selective functionalization of C–H bonds continues to be of great interest to chemists. Inspired byenzymes such as cytochrome P450 and methane monooxygenase (MMO), the use of metal-oxo complexes (M=O) forC–H bond activation has been extensively studied. Analogous reactions with metal-imido (M=NR) species are alsoknown. However, there are only a few reports of C–H bond activation by metal-nitrido (M≡N) complexes. We will reportan example of intermolecular C–H bond activation of a number of alkanes by a highly electrophilic and well-characterized (salen)ruthenium(VI) nitrido complex, [RuVI(N)(L)(MeOH)]PF6 (1).We report that 1 can also undergo facile oxidative C–N bond cleavage of anilines at ambient conditions. There areseveral reports on transition metal-mediated cleavage of aliphatic C–N bonds. On the other hand, there is only oneexample of the activation of the relatively inert C–N bonds of anilines under mild conditions; (tBu3SiO)3Ta undergoesoxidative addition of the C–N bond of p-CF3C6H4NH2 at room temperature to afford (tBu3SiO)3(H2N)Ta(p-C6H4CF3). Catalytic C-C bond formation reactions via C–N cleavage of aniline derivatives catalyzed by a rutheniumcomplex, RuH2(CO)(PPh3)3, have also been reported, however these reactions require high temperature (120 0C).This work was supported by the Research Grants Council of Hong Kong (CityU 101810) and Hong Kong UniversityGrants Committee (AoE/P-03-08) 1. Man, W. L.; Lam, W. W. Y.; Kwong, H. K.; Yiu, S. M.; Lau, T. C. Angew. Chem. Int. Ed. 2012, 51, 9101-9104.2. Man, W. L.; Xie, J.; Pan, Y.; Lam, W. Y. Y.; Kwong, H. K.; Ip, K. W.; Yiu, S. M.; Lau, K. C.; Lau, T. C. J. Am. Chem.Soc., 2013, 135, 5533-5536. (No Image Selected)

CONTROL ID: 1730903TITLE: METAL IONS IN BIOMIMETIC CAVITIESAUTHORS/INSTITUTIONS: O. Reinaud, Université Paris Descartes, Paris, FRANCE|CURRENT CATEGORY: Bioinspired Coordination and Organometallic ChemistryABSTRACT BODY: Abstract Body: The aim of our work is to design supramolecular systems that mimic both the coordination core and thehydrophobic pocket of a metallo-enzyme active site. Our strategy relies on the synthesis of cavity-based ligandsallowing the control of the coordination sphere of the metal ion together with the approach and the binding of anexternal molecule. Since many years, we have been developing systems based on the calix[6]arene scaffold.1 Ourlast developments concerned various aspects such as the guest covalent capture by a host,2 the supramolecularcontrol of hetero-multinuclear binding of metal ions3 and water-soluble receptors.4Recently, we started to explore metal complexes based on the resorcin[4]arene scaffold,5 which provides asupramolecular environment different in shape, rigidity and binding properties. Hence, Bowl vs. Funnelsupramolecular concepts for biomimetic metalcomplexes will be discussed.1. S. Blanchard et al. Angew. Chem., Int. Ed., 1998, 37, 2732-2735. D. Coquière et al. Org. Biomol. Chem., 2009, 7,2485-2500 (Perspective). Supramolecular Copper Dioxygen Chemistry, J.-N. Rebilly, O. Reinaud, in Wiley Series onReactive Intermediates in Chemistry and Biology, Vol. 5 (Series Ed.: S. E. Rokita), Copper-Oxygen Chemistry (Eds.:S. Itoh, K. D. Karlin), Wiley-VCH, Weinheim, 2011. Supramolecular Bioinorganic Chemistry, J.-N. Rebilly and O.Reinaud in Supramolecular Chemistry: From Molecules to Nanomaterials (SMC174), Wiley, 2012. Biomimetic Cavitiesand Bioinspired Receptors, S. Le Gac, I. Jabin, O. Reinaud in “Bioinspiration and Biomimicry in Chemistry” (JohnWiley and Sons, New York), 2013.2. N. Menard et al. Chem., Eur. J., 2013, 19, 642–653. N. Menard et al. Chem. Eur. J. 2013, in press.3. J.-N. Rebilly et al. Inorg. Chem. 2012, 51, 5965-5974. N. Bernier et al. Inorg. Chem. 2012, 52, 4683–4691.4. G. Thiabaud et al. Org. Lett., 2012, 14, 2500–2503. O. Bistri et al. Chem. Sci., 2012, 3, 811–818.5. A. Visnjevac et al.Org. Lett. 2010, 12, 2044–2047.

Found 4 Abstracts CONTROL ID: 1720798TITLE: Metal–Oxo and Metal–Hydroxo Complexes in BiologyAUTHORS/INSTITUTIONS: A.S. Borovik, Department of Chemistry, University of California-Irvine, Irvine, California,UNITED STATES|CURRENT CATEGORY: Bioinspired Coordination and Organometallic ChemistryABSTRACT BODY: Abstract Body: Active sites of proteins containing metal–oxo and hydroxo units have important consequences inmetallobiochemistry. In many cases, they have been proposed to be key intermediates during catalysis, especially inproteins that utilized dioxygen for oxidative transformation. In addition, it has been proposed that intermediatesformed during water oxidation at the oxygen-evolving complex within Photosystem II contain both metal–oxo andmetal–hydroxo units. Developing synthetic systems having similar units has been challenging because of difficulties inreplicating the structural components associated with active sites in metalloproteins. We have been developingsynthetic systems to duplicate some of the structural features found in proteins, including those found within thesecondary coordination sphere (e.g., hydrogen bonding networks). This talk will describe our latest efforts inpreparing and characterizing new metal-oxo and hydroxo complexes with a variety of biological relevant metal ions.Included in the discussion will be methods to prepared heterometallic complexes containing hydroxo and oxo ligands.(No Image Selected)

CONTROL ID: 1720842TITLE: Bio-Inspired, Smart, Multiscale Interfacial MaterialsAUTHORS/INSTITUTIONS: L. Jiang, Institute of Chemistry, Chinese Academy of Sciences, Beijing, CHINA|CURRENT CATEGORY: Bioinspired Coordination and Organometallic ChemistryABSTRACT BODY: Abstract Body: Learning from nature and starting from the superhydrophobic lotus leaves, we revealed that a super-hydrophobic surface needs the cooperation of micro- and nanostructures. Further studies have proved that thearrangement of micro/nano structure can directly affect the wettability and water movements. Recently, we found thathydrophilic compositions together with micro/nano structures endow the fish scale with superoleophobicityunderwater. Inspired by this, artificial fish scales with robust mechanical strength have been fabricated.Based on the micro/nano structured interfaces with special wettability, kinds of basic chemical reactions could be donewithin a small water drop. Crystal arrays could also been prepared, and also small molecule, polymer, silver NPs andmicrospheres can be arrayed in one direction.Under certain circumstances, a surface wettability can switch between superhydrophilicity and superhydrophobicity.Besides the 2D interface, we recently extended the cooperation concept into 1D system. Artificial ion channels withsmart gating properties have been fabricated by integrating smart molecules into the single nanochannels. Theseintelligent nanochannels could be used in energy-conversion system. The other one dimensional system is theartificial spider’s silk. The periodic spindle knots on the spider’s silk can drive liquid drops in a specific direction thatcan collect water from moist air. Further, we prepared artificial spider’s silk and droplets of water on the artificialspider’s silk behaved similarly to those on its biological counterparts. Most recently, inspired by the cactus surviving inthe most drought desert, we probed into the relationship of the structure-function of cactus and found that the cactushad evolved a multi-structural and multi-functional integrated continuous fog collection system.Learning from nature, the constructed smart multiscale interfacial materials system not only presents new knowledge,but also has great applications in various fields, such as self-cleaning glasses, water/oil separation, anti-biofoulinginterfaces, and water collection system.(No Image Selected)

CONTROL ID: 1732521TITLE: A Flexible Nature of Iron-Sulfur Clusters Relevant to Nitrogenase Active Sites :What we know, and What we donot AUTHORS/INSTITUTIONS: K. Tatsumi, Research Center for Materials Science, Nagoya University, Nagoya, JAPAN|CURRENT CATEGORY: Bioinspired Coordination and Organometallic ChemistryABSTRACT BODY: Abstract Body: The biochemical study of reductases has made a rapid progress in recent years. Newly discoveredreductases contain unprecedented transition metal sulfide clusters at the active centers, which are so unusual thatchemistry should strive to understand their structure-function relationship.We have discovered a new method to synthesize metastable Fe/S clusters in non-polar solvents using Fe{N(TMS)2}2(TMS = SiMe3) as the precursor, resulting in isolation of new clusters with structural diversity. This developmentdemonstrates a power of chemical synthesis, and reveals that the iron-sulfur clusters can be more flexible eitherelectronically or geometrically than we might anticipate. For instance, we isolated all-ferric Fe4S4{N(TMS)2}4 cubanecluster, and found that it readily splits into two Fe2S2 clusters. The [8Fe7S] inorganic core of P-cluster (PN) ofnitrogenase was synthesized from a reaction of Fe{N(SiMe3)2}2, tmtu, HSTip, and S8 in toluene (1). We have alsosynthesized a model of the oxidized P-cluster (2), in which an Fe-S bond of the [8Fe7S] core is cleaved. Interestingly,addition of tmtu to (2) promotes the Fe-S bond formation with the core being reduced by one electron. Yet anothertype of [8Fe7S] cluster (3) was synthesized from the reaction of a preformed di-iron complex [Fe(STip)]2(μ-SDmp)2with S8, the structures of which may link topologically the FeMo-co and P-cluster. The analogous reaction ofFe{N(SiMe3)2}2 with 2 eq of HSTip and 1/16 eq of S8 in toluene/ether gave rise to a [9Fe5S] cluster (4), whichconsists of a trigonal prismatic [6Fe5S] core without an atom incapsulated in the 6Fe trigonal prism. Furthermore, anO-atom incorporated [8Fe6S1O] cluster (5) was isolated from the reaction of [Fe(OCPh3)]2(μ-SDmp)2 with S8 underthe presence of 1/4 equiv of H2O, which indicates flexibility of the FeMo-co core geometry.1. Y. Ohki et al., J. Am. Chem. Soc., 131, 13168 (2009).2. T. Matsumoto et al., Nature, 462, 514-518 (2009).3. Y. Ohkiet al.Proc. Nat. Acad. Sci. (USA), 107, 3994-3997 (2010).4. Y. Ohki et al., Proc. Nat. Acad. Sci. (USA), 108, 12635-12640 (2011).

CONTROL ID: 1752221TITLE: Electrochemistry of Metal Complexes of Biological Interest. CatalysisAUTHORS/INSTITUTIONS: J. Savéant, Laboratoire d’électrochimie moléculaire, Université Paris Diderot, Paris,FRANCE|CURRENT CATEGORY: Bioinspired Coordination and Organometallic ChemistryABSTRACT BODY: Abstract Body: Determination of "redox potentials" seems obsessive to many (bio)chemists when they callelectrochemistry for help. Unfortunately, cyclic voltammetric responses are not always "nice and reversible" (seebelow) making it a little more complicated to access "redox potentials". The positive counterpart is that a wealth ofmechanistic and kinetic information is contained in these "monster CVs". Molecular electrochemistry is thus anefficient approach to electron transfer chemistry thanks to the easy control of the driving force by means of theelectrode potential while the current provides a straightforward measure of the reaction kinetics. A few Illustratingexamples will be presented: proton-coupled redox thermodynamics of Vitamin B12, 1 mechanisms of reductivedehalogenation in B12 and dehalogenases, 2,3 catalysis and inhibition in horseradish peroxidase, 4 proton-coupledcatalysis of CO2 reduction by electrogenerated iron(0) porphyrins, 5,6 remarkably efficient catalysis by iron-porphyrinbearing acid groups on the catalyst molecule. 7 In these processes and others, electron transfer is often associatedwith proton transfer and also with breaking of heavy-atom bonds. Association may be so intimate as to becomeconcertation. Starting from models of simple outersphere electron transfers, 8,9 of dissociative electron transfer, 10 ofconcerted proton-electron transfer with no bond breaking,11 a model of reactions where all three events are concertedis now available. 12[1] Lexa, D et al. Acc. Chem. Res. 1983, 16, 235. [2] Diekert, G et al. J. Am. Chem. Soc. 2005, 127, 13583.3]Costentin, C et al. J. Am. Chem. Soc. 2005, 127, 12154;[4] Dequaire, M et al. J. Am. Chem. Soc. 2002, 124, 240.[5]Costentin, C et al. J. Am. Chem. Soc. 2012, 134, 11235.[6] Costentin, C et al.M. J. Am. Chem. Soc. 2013, DOI:10.1021/ja4030148.[7] Costentin, C. et al.Science 2012, 338, 90.[8] Marcus, R. A. J. Chem. Phys. 1956, 24, 966.[9]Hush, N. S. J. Chem. Phys. 1958, 28 , 962[10] Savéant, J.-M J. Am. Chem. Soc. 1987, 109, 6788.[11] Costentin, C. Etal.Chem. Rev. 2010, 110, PR1-PR40.[12] Costentin, C. Et al. Proc. Nat. Acad. Sci. U.S.A. 2011, 108, 8559.