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′-C H O )POCH CH OCH , 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 LiBPh ·3dme, NaBPh and HgCl . 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) (1) , 6, cis-PtCl (1) , 7, and PdCl (1) , 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 HgCl has been carried out to determine the cis-trans preference of 1 in the octahedral coordination geometry. © 2010 Elsevier B.V. All rights reserved. 12 8 2 2 2 3 4 4 2 4 2 2 2 2 2 2 + +
