Electrocatalytic Ammonia Oxidation with Coordinatively Saturated Ruthenium Catalyst.

This communication describes the investigation of a coordinatively saturated complex [Ru(tpy)(dmabpy)Cl] ([Ru(Cl)]) as an ammonia oxidation catalyst. Cyclic voltammetry measurements show an ideal S-shaped wave, indicating total catalysis conditions with a (TOF) of 9360 h. The reaction was found to be first-order in [Ru(Cl)] and third-order in [NH]. Stoichiometric reactions of the one-electron oxidized species, [Ru(Cl)], were monitored following the addition of NH using H and N NMR spectroscopy. These experiments showed that the chloride-coordinated complex rapidly converts NH to N. NMR spectroscopy and electrochemistry results definitively show that NH does not substitute the Cl ligand to form the previously reported [Ru(NH)] catalyst which operates by a different mechanistic pathway. Taken together these results indicate outersphere electron transfer mediated ammonia oxidation reaction.