Binuclear Nickel(II) Complex with a Bridging 2,2′-Bibenzimidazole Ligand for Carbon Dioxide Electroreduction

The electrocatalytic activity of the binuclear nickel(II) complex [Ni2(μ-Me4-bbim)(bpy)4][(BF4)2], where Me4-bbim is 5,5′,6,6′-tetramethyl-2,2′-bibenzimidazole and bpy is 2,2′-bipyridine, in the carbon dioxide reduction process was studied. The formation of an active Ni(I) species (g = 2.15), which effectively reacts with CO2, was revealed using in situ EPR spectroelectrochemistry and cyclic voltammetry. Preparative electrolysis in a DMF–H2O medium demonstrated the efficiency of the complex in the electrocatalytic reduction of CO2 to methane and formate.