Abstract/Summary

A series of molybdenum tetracarbonyl complexes with dimethyl‐substituted 2,2′‐bipyridine (dmbipy) ligands were investigated by cyclic voltammetry (CV) combined with infra‐red spectroelectrochemistry (IR‐SEC) in tetrahydrofuran (THF) and N‐methyl‐2‐pyrrolidone (NMP) to explore their potential in a reduced state to trigger electrocatalytic CO2 reduction to CO. Addressed is their ability to take advantage of a low‐energy, CO‐dissociation two‐electron ECE pathway available only at an Au cathode. A comparison is made with the reference complex bearing unsubstituted 2,2ʹ‐bipyridine (bipy). The methyl substitution in the 6,6ʹ‐positions has a large positive impact on the catalytic efficiency. This behaviour is ascribed to the advantageous positioning of the steric bulk of the methyl groups, which further facilitates CO dissociation from the 1e‐ reduced parent radical anion. In the contrary, the substitution in the 4,4′‐positions appears to have a negative impact on the catalytic performance, exerting a strong stabilizing effect on the π‐accepting CO ligands and, in THF, preventing exploitation of the low‐energy dissociative pathway.