Four-Electron Reduction of Diazo Compounds at a Single Tungsten Metal Center: A Theoretical Study of the Mechanism

A possible mechanism for the unprecedented one-metal reduction of diazobenzene by the [W(OC 6 HPh 3 -η 6 -C 6 H 5 )(OAr)(PMe 2 Ph)] (OAr = 2,3,5,6-tetraphenyloxide) complex was characterized by hybrid Becke3LYP DFT calculations on the model system [W(OH) 2 (C 6 H 6 )(Ph 3 )]+ N 2 H 2 . The model reaction is shown to be strongly exothermic, and takes place via a multistep process with moderate activation energy barriers. We discuss how this specific set of ancillary ligands permits the reaction to occur on a one-metal system in place of the more usual two-metal systems.