Catalytic Hydrogenation of Alkenes by the Ruthenium−Carbene Complex HRu(CO)Cl(PCy₃)(IMes) (IMes = Bis(1,3-(2,4,6-trimethylphenyl)imidazol-2-ylidene)

Using an exchange reaction involving one PCy 3 ligand in HRu(CO)Cl(PCy 3 ) 2 ( 1 ) for one IMes, a ruthenium−hydride complex HRu(CO)Cl(PCy 3 )(IMes) ( 2 ) has been prepared. Complex 2 is an active catalyst in the hydrogenation of alkenes. A TON of 24 000 h - 1 has been obtained at 100 °C under 4 atm of hydrogen. Addition of HBF 4 ·OEt 2 as cocatalyst enhanced the catalytic activity.