( n -Bu) 4 NBr-Promoted N 2 Splitting to Molybdenum Nitride.

Splitting of N via six-electron reduction and further functionalization to value-added products is one of the most important and challenging chemical transformations in N fixation. However, most N splitting approaches rely on strong chemical or electrochemical reduction to generate highly reactive metal species to bind and activate N, which is often incompatible with functionalizing agents. Catalytic and sustainable N splitting to produce metal nitrides under mild conditions may create efficient and straightforward methods for N-containing organic compounds. Herein, we present that a readily available and nonredox (-Bu)NBr can promote N-splitting with a Mo(III) platform. Both experimental and theoretical mechanistic studies suggest that simple X (X = Br, Cl, etc.) anions could induce the disproportionation of Mo[N()Ar] at the early stage of the catalysis to generate a catalytically active {Mo[N()Ar]} species. The quintet Mo species prove to be more favorable for N fixation kinetically and thermodynamically, compared with the quartet Mo counterpart. Especially, computational studies reveal a distinct heterovalent {Mo-N-Mo} dimeric intermediate for the N≡N triple bond cleavage.