Cobalt analogs of Ru-based water oxidation catalysts: overcoming thermodynamic instability and kinetic lability to achieve electrocatalytic O-2 evolution

Several binuclear cobalt(III) complexes that mimic Ru-based water oxidation catalysts have been prepared. The initial complexes exhibited thermodynamic instability and kinetic lability that complicated efforts to use these cobalt complexes as electrocatalysts for water oxidation. Binuclear cobalt(III) complexes supported by a bridging bispyridylpyrazolate (bpp) ligand overcome these limitations. Two bpp-ligated dicobalt(III)-peroxo complexes were prepared and structurally characterized, and electrochemical investigation of these complexes supports their ability to serve as molecular electrocatalysts for water oxidation under acidic conditions (pH 2.1).