Preparation and characterization of rhodium(I) complexes containing bidentate diphenyl(prop-2-enyloxo)phosphine and (but-3-enyl)diphenylphosphine ligands

Abstract

The complexes [LRh(µ-Cl)₂RhL] and [RhL(L′)][L′=η-cyclopentadienyl (cp) or pentane-2,4-dionato (acac); L = diphenyl(prop-2-enyloxo)phosphine-P;C²,C³-η(dppp) or (but-3-enyl)diphenylphosphine-P;C³,C⁴-η(bdpp)] have been prepared and characterized. The strongest metal–olefin bond occurs in the cp complexes and can be recognized by significant changes in spin–spin coupling involving the olefinic protons and a large upfield shift of the terminal olefinic protons (as high as τ 9). Unequal coupling constants ³J(POCH) of 34 and 6·5 Hz for the complex [Rh(cp)(dppp)] and similar values for [Rh(acac)(dppp)] allow assignment of the configuration of the ligand and of the molecular structures of the complexes in solution.