Ruthenium dihydride RuH2(PPh3)2((R,R)-cyclohexyldiamine) and ruthenium monohydride RuHCl(PPh3)2((R,R)-cyclohexyldiamine):: Active catalyst and catalyst precursor for the hydrogenation of ketones and imines

The new monohydride RuHCl(PPh3)(2)(R,R-cydn) with base added, and dihydride RuH2(PPh3)(2)(R,R-cydn), in the absence of base, catalyze the hydrogenation of a wide variety of ketones and some imines at 3 atm of H-2 and 20 degrees C with high turnover numbers. The mechanism is thought to involve the concerted dihydrogen transfer from cis hydride and N-H groups to the substrate followed by heterolytic dihydrogen splitting.