Electrocatalytic reduction of CO2 to CO and HCO2− with Zn(II) complexes displaying cooperative ligand reduction

Air-stable zinc(II) pyridyl phosphine complexes, [Zn(κ2-2,6-{Ph2PNMe}2(NC5H3))Br2] (1) and [Zn(κ2-2-{Ph2PNMe}(NC5H3))Br2] (2) are reported and 1 was capable of electrocatalytic reduction of CO2 at −2.3 V vs. Fc+/0 to yield CO/HCO2H in mixed water/acetonitrile solutions. DFT computations support a proposed mechanism involving electron transfer reactions from a species with the anionic PN3P ligand (“L−/Zn(II)”).