Volume 61, Issue 1 e202109645
Communication
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Mediated Inner-Sphere Electron Transfer Induces Homogeneous Reduction of CO2 via Through-Space Electronic Conjugation**

Shelby L. Hooe

Shelby L. Hooe

Department of Chemistry, University of Virginia, McCormick Road, PO Box 400319, Charlottesville, VA, 22904-4319 USA

These authors contributed equally to this work.

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Juan J. Moreno

Juan J. Moreno

Department of Chemistry, University of Virginia, McCormick Road, PO Box 400319, Charlottesville, VA, 22904-4319 USA

These authors contributed equally to this work.

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Amelia G. Reid

Amelia G. Reid

Department of Chemistry, University of Virginia, McCormick Road, PO Box 400319, Charlottesville, VA, 22904-4319 USA

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Emma N. Cook

Emma N. Cook

Department of Chemistry, University of Virginia, McCormick Road, PO Box 400319, Charlottesville, VA, 22904-4319 USA

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Charles W. Machan

Corresponding Author

Charles W. Machan

Department of Chemistry, University of Virginia, McCormick Road, PO Box 400319, Charlottesville, VA, 22904-4319 USA

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First published: 25 October 2021
Citations: 21
**

A previous version of this manuscript has been deposited on a preprint server (https://doi.org/10.26434/chemrxiv.14165951.v1.).

Graphical Abstract

Through-space electronic conjugation between a redox mediator and molecular Cr complex enables emergent co-electrocatalytic activity for the electrochemical reduction of carbon dioxide to carbon monoxide. In the reduced forms, the aromatic portions interact through a combination of dispersion forces, π conjugation, and weak coordination of the sulfone to Cr.

Abstract

The electrocatalytic reduction of CO2 is an appealing method for converting renewable energy sources into value-added chemical feedstocks. We report a co-electrocatalytic system for the reduction of CO2 to CO comprised of a molecular Cr complex and dibenzothiophene-5,5-dioxide (DBTD) as a redox mediator, which achieves high activity (TOF=1.51–2.84×105 s−1) and quantitative selectivity. Under aprotic or protic conditions, DBTD produces a co-electrocatalytic response with 1 by coordinating trans to the site of CO2 binding and mediating electron transfer from the electrode with quantitative efficiency for CO. This assembly is reliant on through-space electronic conjugation between the π frameworks of DBTD and the bpy fragment of the catalyst ligand, with contributions from dispersive interactions and weak sulfone coordination.

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