A possible mechanism for the unprecedented one-metal reduction of diazobenzene by the [W(OC6HPh3-eta(6)-C6H5)(OAr)(PMe2Ph)] (OAr = 2,3,5,6-tetraphenyloxide) complex was characterized by hybrid Becke3LYP DFT calculations on the model system [W(OH)(2)(C6H6)(Ph-3)]+ N2H2 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.