Hydrazine Formation via Coupling of a Nickel(III)-NH Radical.

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