Ruthenium(II) complexes of optically active P, N donor ligands. Synthesis and evaluation in the catalytic hydrogenation of acetophenone

The reaction of 2 equiv of the optically active P, N bidentate ligands 1-3 with RuCl2(PPh3)(3) gives the RuCl2(1-3)(2) (4-6) complexes in good yield a s a mixture of isomers. The solid state structure of RuCl2(2)(2) (5c) is de scribed: the two chlorine atoms are in trans position and due to steric cro wding, one of the two ligands 2 is more weakly bound to Ru. The complexes 4 -6 show moderate to good catalytic activity for the hydrogenation of acetop henone in basic media in hydrogen transfer conditions, from propanol-2, or under dihydrogen, but: the enantiomeric excesses are low. (C) Academie des sciences/Elsevier, Paris.