Water-splitting and Catalyzed Ester Synthesis with

Organomanganese(I) Carbonyl Complexes

Replacing ruthenium(II) with manganese(I)

Abstract

Metal catalysts are an important component of industrially relevant chemical reactions and aids

in producing massive amounts of chemicals in a short span of time. Unfortunately, a lot of

chemical reactions relevant to society are catalyzed by expensive or toxic metal complexes.

Manganese is a first row transition metal that is earth-abundant and non-toxic. Recently,

manganese compounds have gained a lot of attention in the field of catalysis due to its ability to

catalyze transformations that were previously catalyzed by ruthenium. For this reason, the

research of Karthika Kadassery in the Lacy research group details efforts toward synthesis and

characterization of novel manganese compounds. The findings are that certain manganese

complexes enable the synthesis of ester compounds, which are important molecules in food and

pharmaceutical chemical industry. The manganese compounds also exhibit thermochemical and

photochemical properties that allowed for new strategies of harnessing sunlight into stored

chemical energy. These and other efforts exemplify some of the sustainable science being

conducted in the Lacy research group by Karthika Kadassery.

Coordination chemistry of Mn(I) with tridentate H-POP ligand Coordination chemistry of Mn(I) with bidentate H-PO ligand

Our previous work which led to current study

Acknowledgement

ReferencesCatalysis (Tishchenko reaction)

Karthika J. Kadassery,† Samantha N. MacMillan,§ David C. Lacy*†

† Department of Chemistry, University at Buffalo, State University of New York, Buffalo, NY 14260, United States§ Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, United States

No Catalyst Yield (%)

1 POPMn(CO)3 26

2 {POPMn(CO)3}2 52

3 - 0

4 H-POP 0

5 H-POP + MnBr2 0

6 MnBr(CO)5 0

7 {H-POP}{Mn(CO)4Br}2 0

8 POPMn(CO)3‧HBr 0

1. Kadassery, K. J.; Dey, S. K.; Friedman, A. E.; Lacy, D. C. Inorg. Chem. 2017, 56 (15), 8748.

2. Kadassery, K. J.; Dey, S. K.; Cannella, A. F.; Surendhran, R.; Lacy, D. C. Inorg. Chem. 2017, 56 (16), 9954.

3. Kadassery, K. J.; MacMillan, S. N.; Lacy, D. C. Dalton Trans. 2018, 47 (36), 12652.

4. Kadassery, K. J.; Lacy, D. C. Dalton Trans. 2019, 48, 4467.

5. Kadassery, K. J.; Sethi, K.; Fanara, P. M.; Lacy, D. C. Inorg. Chem 2019, 58 (7), 4679.

6. Kadassery, K. J.; MacMillan, S. N.; Lacy, D. C. Inorg. Chem. 2019, 58 (16), 10527.

7. Kadassery, K. J.; MacMillan, S. N.; Lacy, D. C. Dalton Trans. 2020. Manuscript under review.

3.245 A°

Since the 2016 finding that Mn(I) pincer complexes with bifunctional ligands are active

(de)hydrogenation catalysts, many have been striving to replace expensive Ru-based catalysts

Saudan et. al. Org. ProcessRes. Dev. 2012, 16, 166

Milstein et. al. J. Am. Chem. Soc. 2005, 127, 10840 Beller et. al. Angew. Chem. Int. Ed.. 2016, 55, 15364

Milstein et. al. J. Am. Chem. Soc. 2016, 138, 4298

Photochemical water-splitting

3600 2700 1800 900

0.7

0.8

0.9

1.0

Tra

nsm

itta

nce

Wavenumber (cm-1)

First phenol bound Mn(I) complex

First Mn(I) catalyzed Tishchenko reaction

Coordination induced O–H bond weakening

-1.2 -1.0 -0.8 -0.6 -0.4 -0.2 0.0

-0.02

0.00

0.02

0.04

Cu

rre

nt

(mA

)

Potential (V) vs. Fc/Fc+

200 mV/s

300 mV/s

400 mV/s

500 mV/s

600 mV/s

700 mV/s

• BDFEO–H of H1 ≈ 73 kcal/mol

• BDFEO–H of phenol ≈ 85 kcal/mol

• Coordination induced O-H bond

weakening, ΔBDFE ≈ 10 kcal/mol)

• Soft-homolysis of O-H bond weakened

by coordination has emerging utility in

energy science and chemical synthesis.

Figure. Cyclic voltammogram [1]– in MeCN.

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