A RUTHENIUM(II) COMPLEX WITH A C-2-SYMMETRICAL DIPHOSPHINE DIAMINE TETRADENTATE LIGAND FOR ASYMMETRIC TRANSFER HYDROGENATION OF AROMATIC KETONES/

The trans-(RuCl2)-Cl-II complexes with structurally similar henylphosp hino)benzylidene]cyclohexane-1,2-diamine and (diphenylphosphino)-benzy l]cyclohexane-1,2-diamine ligands have been synthesized, and their mol ecular structures have been determined. The C-2-symmetric diphosphine/ diamine-based Ru complex acts as an excellent catalyst precursor in as ymmetric transfer hydrogenation of acetophenone in a 0.1 M 2-propanol solution, leading to 2-phenylethanol in 97% ee and in 93% yield after 7 h at 45 degrees C. This transfer hydrogenation is characterized by l ow reversibility under these conditions.