Synthesis, characterization and coordination chemistry of a new phosphite-ether ligand: The effects of alkali metal salts and the ligand/Rh molar ratio on the catalytic activity and regioselectivity of a Rh(I) complex of this ligand in the hydroformylation of styrene

Academic Article


  • We have recently reported that the addition of alkali metal salts to styrene hydroformylation reactions catalyzed by Rh(I) complexes of bis(phosphite) ligands can significantly improve the iso/n regioselectivity. To better understand the effects of the alkali metal salts on these styrene hydroformylation reactions, a monodentate phosphite-ether ligand, (2,2′-C12H8O2)POCH2CH2OCH3, 1 has been prepared, and its Rh(I) complex has been evaluated as a catalyst for the hydroformylation of styrene. Both the activity and regioselectivity of the catalyst are sensitive to the ligand:Rh molar ratio and to the presence of salts such as LiBPh4·3dme, NaBPh4 and HgCl2. The most active catalyst has a 1:2.5 Rh:1 molar ratio and a 1:8 Rh:Li+ molar ratio, but the most regioselective catalyst has a 1:8.2 Rh:1 ratio and a 1:4 Rh:Li+ ratio. Model complexes for various steps in the catalytic cycle, cis-Mo(CO)4(1)2, 6, cis-PtCl2(1)2, 7, and PdCl2(1)2, 8, have been synthesized and characterized by multinuclear NMR spectroscopy and X-ray crystallography to provide insight into the factors that may affect the rates and regioselectivities of the hydroformylation catalysts. The cis-trans isomerization of 6 in the presence of catalytic amount HgCl2 has been carried out to determine the cis-trans preference of 1 in the octahedral coordination geometry. © 2010 Elsevier B.V. All rights reserved.
  • Authors

    Published In

    Digital Object Identifier (doi)

    Pubmed Id

  • 16642049
  • Author List

  • Kaisare AA; Owens SB; Valente EJ; Gray GM
  • Start Page

  • 1472
  • End Page

  • 1479
  • Volume

  • 695
  • Issue

  • 10-11