Mediated Inner-Sphere Electron Transfer Induces Homogeneous Reduction of CO2 via Through-Space Electronic Conjugation

27 April 2021, Version 2
This content is a preprint and has not undergone peer review at the time of posting.


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 x 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. The resulting interaction stabilizes a key intermediate in a new aprotic catalytic pathway and lowers the energy of the rate-determining transition state under protic conditions. To the best of our knowledge through-space electronic conjugation has not been explored in molecular electrocatalytic systems.


carbon dioxide

Supplementary materials

Cr CO2RR Mediator DBTD SI RevisionFinal


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