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 H₂ and 20 °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.