Abstract
M(NH(x) ) intermediates involved in N-N bond formation are central to ammonia oxidation (AO) catalysis, an enabling technology to ultimately exploit ammonia (NH(3) ) as an alternative fuel source. While homocoupling of a terminal amide species (M-NH(2) ) to form hydrazine (N(2) H(4) ) has been proposed, well-defined examples are without precedent. Herein, we discuss the generation and electronic structure of a Ni(III) -NH(2) species that undergoes bimolecular coupling to generate a Ni(II) (2) (N(2) H(4) ) complex. This hydrazine adduct can be further oxidized to a structurally unusual Ni(2) (N(2) H(2) ) species; this releases N(2) in the presence of NH(3) , thus establishing a synthetic cycle for Ni-mediated AO. Distribution of the redox load for H(2) N-NH(2) formation via NH(2) coupling between two metal centers presents an attractive strategy for AO catalysis using Earth-abundant, late first-row metals.