A concerted transfer hydrogenolysis: 1,3,2-diazaphospholene-catalyzed hydrogenation of Ni-34;N bond with ammonia-borane

1,3,2-diazaphospholenes catalyze metal-free transfer hydrogenation of a Ni-34;N double bond using ammonia-borane under mild reaction conditions, thus allowing access to various hydrazine derivatives. Kinetic and computational studies revealed that the rate-determining step involves simultaneous breakage of the B-H and N-H bonds of ammonia-borane. The reaction is therefore viewed as a concerted type of hydrogenolysis. On the double: Diazaphospholenes catalyze the transfer hydrogenation of a Ni-34;N bond under mild reaction conditions, allowing access to various hydrazine derivatives. The catalytic cycle involves two key steps, and the catalyst maintains the P^III oxidation state throughout the catalytic cycle. The reaction mechanism involves a hydrogenolysis of the exocyclic P-N bond of the intermediate by ammonia-borane, and it proceeds in a concerted double-hydrogen-transfer fashion.