A Cis-Bis-Mixed-Carbene Ruthenium Hydride Complex: An Olefin-Selective Hydrogenation Catalyst

The N-heterocyclic carbene C 3 H 2 N 2 (CH 2 CH 2 OMe) 2 ( 1; IOMe) reacts with RuHCl(PPh 3 ) 3 to give RuClH(IOMe)(PPh 3 ) 2 ( 2 ), which reacts further with SIMes to give the cis-bis-mixed-carbene complex RuClH(IOMe)(SIMes)(PPh 3 ) ( 3 ). This species has been shown to be a highly effective hydrogenation catalyst that tolerates the presence of a wide range of functional and donor groups.