Dinitrogen Cleavage by a Three-Coordinate Molybdenum (III) Complex

Cleavage of the relatively inert dinitrogen (N_2) molecule, with its extremely strong NequivN triple bond, has represented a major challenge to the development of N_2 chemistry. This report describes the reductive cleavage of N_2 to two nitrido (N^3-) ligands in its reaction with Mo(NRAr)_3, where R is C(CD_3)_2CH_3 and Ar is 3,5-C_6H_3(CH_3)_2, a synthetic three-coordinate molybdenum(III) complex of known structure. The formation of an intermediate complex was observed spectroscopically, and its conversion (with NequivN bond cleavage) to the nitrido molybdenum(VI) product NequivMo(NRAr)_3 followed first-order kinetics at 30^circC. It is proposed that the cleavage reaction proceeds by way of an intermediate complex in which N_2 bridges two molybdenum centers.