Triphos nickel(II) halide pincer complexes as robust proton reduction electrocatalysts

Abstract

Three air-stable Triphos nickel(II) halide pincer complexes (Triphos = bis(2-diphenylphosphinoethyl)phenylphosphine) have been prepared and tested as proton reduction electrocatalysts using acetic acid or trifluoroacetic acid as the proton source in acetonitrile. Electrochemical studies have found them to be robust catalysts with the iodide complex exhibiting the lowest overpotential of 0.52 V in the presence of acetic acid. A proton reduction catalytic mechanism has also been proposed based on the experimental data and density functional calculations performed on a structurally-similar model complex.