Ligand-Assisted Electrochemical CO2 Reduction by Ru-Polypyridyl Complexes

The introduction of a simple triazole moiety on a terpyridine ligand in the complex [Ru(tpy)(bpy)(Cl)](+) ([1](+); tpy = 2,2':6',2''-terpyridine; bpy = 2,2'-bipyridine) gives rise to a suitable electrocatalyst for the reduction of CO2 to CO. The triazole group in [Ru(tpyaz)(bpy)(Cl)](+) {[2](+); tpyaz = 4'-[4-(tert-butylphenyl)-1H-1,2,3-triazol-4-yl]-2,2':6',2''-terpyridine} enables the complex [2](+) to bind with CO2 even at the one-electron reduced state of the complex. Further 2(nd)-electron addition after CO2-coordination to the catalyst facilitates efficient CO2 reduction, based on cyclic voltammetry analysis.