A Bioinspired Molybdenum-Copper Molecular Catalyst for CO2 Electroreduction

Non‐noble metal molecular catalysts mediating the electrocatalytic reduction of carbon dioxide are still scarce. This work reports the electrochemical reduction of CO2 to formate catalyzed by the bimetallic complex [(bdt)MoVI(O)S2CuICN]2‐ (bdt = benzenedithiolate), a mimic of the active site of the Mo‐Cu carbon monoxide dehydrogenase enzyme (CODH2). Infrared spectroelectrochemical (IR‐SEC) studies coupled with density functional theory (DFT) computations revealed that the complex is only a pre‐catalyst, the active catalyst being generated upon reduction in the presence of CO2. We found that the two‐electron reduction of [(bdt)MoVI(O)S2CuICN]2‐ triggers the transfer of the oxo moiety to CO2 forming CO3 2‐and the complex [(bdt)MoIVS2CuICN]2– and that a further oneelectron reduction is needed to generate the active catalyst. Its protonation yields a reactive MoVH hydride intermediate which reacts with CO2 to produce formate. These findings are particularly relevant to the design of catalysts from metal oxo precursors.