Electrocatalytic CO2 reduction with nickel complexes supported by tunable bipyridyl-N-heterocyclic carbene donors: understanding redox-active macrocycles

A series of nickel complexes featuring redox-active macrocycles is reported for electrocatalytic CO2 reduction. A remarkable structure–activity relationship is elucidated from the series through electrochemical studies and DFT calculations, wherein a fine electronic balance between metal and ligand redox chemistry dictates selectivity for CO2 reduction versus the competing proton reduction reaction.