Structural studies of some rhodium(III) acyl complexes containing bidentate phosphines

Abstract

Acyl complexes of rhodium(III) with chelating diphosphine ligands are well known for their stability toward decarbonylation. This stability has allowed us to synthesize and structurally characterize a series of ten related complexes of the type Rh(diphosphine)(COR)I2. All ten display the same square pyramidal geometry with the acyl group in the apical position. The orientation of the acyl ligand is determined by both steric factors and CH⋯O hydrogen bonding between the acyl oxygen and C–H groups on the diphosphine ligand. Results indicate that bis(diphenylphosphino)benzene is significantly more sterically demanding and less electron donating than the bis(diphenylphosphino)propane and bis(diisopropylphosphino)propane ligands.