J. Bakos, I. Tóth, B. Heil
Jul 11, 1989
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Journal
Journal of Organometallic Chemistry
Abstract
Abstract Rhodium(I) complexes formed by (−)-(2 S ,4 S )-2,4-bis(diphenylphosphino)pentane (BDPP) are efficient catalysts for the hydrogenation of acetophenone and acetophenonebenzylimine. The composition of the solvent mixture and the reaction temperature have a marked influenced on the enantioselectivity. These effects are thought to be related to the enhanced conformational flexibility of six-membered rings when simple substrates without functional groups are coordinated to the rhodium. X-ray crystallographic studies reveal that in [Rh(( S , S )-BDPP)NBD] + ( 1 ) the ligand is in a chair conformation, and that in [Rh(( S , S )-BDPP)COD] + ( 2 ) the chelate ring is in a δ-skew conformation. Studies of Rh(( S , S )-BDPP)(NBD)Cl ( 3 ) in solution indicate a trigonal bipyramidal structure with a chair conformation of the ring in aromatic solvents and a conformationally labile ring in methanol.