Improved Syntheses of Versatile Ruthenium Hydridocarbonyl Catalysts Containing Electron‐Rich Ancillary Ligands

Clean, high‐yield routes are established to the important catalyst chlorobis(tricyclohexylphosphine)ruthenium hydridocarbonyl [RuHCl(CO)(PCy 3 ) 2 ] 2 and its N‐heterocyclic carbene (NHC) derivatives RuHCl(CO)(NHC)(PCy 3 ) ( 3a : NHC=IMes; 3b , NHC=H 2 IMes; IMes=1,3‐dimesitylimidazol‐2‐ylidene). These complexes are obtained by treating chlorotris(tricyclohexylphosphine)ruthenium hydridocarbonyl [RuHCl(CO)(PPh 3 ) 3 ] 1 with tricyclohexylphosphine [PCy 3 ], or with the appropriate NHC ligand, then PCy 3 . Advantages over prior routes to these complexes lie in the high yields from a conveniently accessible precursor, the absence of by‐products that otherwise prove difficult to remove, and the short reaction times under experimentally convenient conditions.