Electrocatalytic Reduction of CO₂ and H₂O with Zn(II) Complexes Through Metal‐Ligand Cooperation

Abstract

Air and water‐stable zinc (II) complexes of neutral pincer bis(diphenylphosphino)‐2,6‐di(amino)pyridine (“PN3P”) ligands are reported. These compounds, [Zn(κ2‐2,6‐{Ph2PNR}2(NC5H3))Br2] (R = Me, 1; R = H, 2), were shown to be capable of electrocatalytic reduction of CO2 at ‐2.3 V vs. Fc+/0 to selectively yield CO in mixed water/acetonitrile solutions. These complexes also electrocatalytically generate H2 from water in acetonitrile solutions, at the same potential, with Faradaic efficiencies of up to 90%. DFT computations support a proposed mechanism involving the first reduction of 1 or 2 occurring at the PN3P ligand. Furthermore, computational analysis suggested a mechanism involving metal‐ligand cooperation of a Lewis acidic Zn(II) and a basic ligand.