Molecular electrocatalysts for oxidation of H2 typically require that one metal bind H2, heterolytically cleave the H2, and then undergo two electrochemical oxidations and two deprotonation steps. We previously developed mononuclear Ni, Fe and Mn electrocatalysts for oxidation of H2 where a pendant amine facilitates the heterolytic cleavage of H2, delivering a proton to the amine and a hydride to the metal. We recently discovered a different type of catalyst system, where the electrocatalytic oxidation of H2 is catalyzed by a cooperative system using Cp*Cr(CO)3H and [Fe(PEtNMePEt)(CO)3]+. A key step of the proposed mechanism is a rarely observed metal-to-metal hydrogen atom transfer. The Cr-H complex donates a hydrogen atom to the Fe, forming a Fe-H bond that is deprotonated and then oxidized electrochemically. This cooperative catalysis system does not require that either metal heterolytically cleave H2, and provides an unusual example of a homolytic reaction being a key step in a molecular electrocatalytic process.

Hydrogen oxidation electrocatalysis involving hydrogen atom transfer: A homolytic approach to a heterolytic reaction

255th National Meeting (2018)

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