Ruthenium(II) N,S-heterocyclic carbene complexes and transfer hydrogenation of ketones

Abstract

A series of ruthenium(II) N,S-heterocyclic carbene (NSHC) complexes Ru IIX(RCOO)(PPh3)2(3-R′BzTh) (BzTh = benzothiazol-2-ylidene; R = Me, R′/X = Bz/Br (4), Pri/I (6), Bui/I (8); R = Et, R′/X = Bz/Br (5), Pri/I (7), Bui/I (9)) have been synthesized and characterized. Single-crystal X-ray structural analysis revealed that in each case the Ru(II) center adopts an essentially octahedral geometry, coordinated by two trans-oriented PPh 3 completed by an NSHC, chelating carboxylate and halide X (X = Br (4-5), X = I (6-9)) ligands. Although thiazol-2-ylidiene Ru(II) complexes are established and applied in metathesis, these benzothiazol-2-ylidene complexes (4-9) are the first of its kind. Their catalytic activities towards transfer hydrogenation of ketones have been examined and discussed. © The Royal Society of Chemistry 2010.