Nickel(II) and palladium(II) complexes of diphenylphosphinoacetone and its enolate

Abstract

Complexes of diphenylphosphinoacetone (HL = Ph2PCH2COMe), [NiCl2(HL)2]1, [PdCl2(HL)2]2 and its enolate [NiL2]3 and [PdL2]4, have been synthesized and characterized by 31P, 1H NMR and IR spectroscopy. Single-crystal X-ray diffraction studies of 1–3 reveal square-planar geometry at the central atom. There is a trans arrangement in 1 and 2 and a cis arrangement for 3. A 1H NMR spin-saturation transfer experiment indicates that the complex 2 exists as a cis–trans equilibrium mixture in CDCl3 solution. Complex 4 has a structure analogous to that of 3, as revealed by 1H NMR spectroscopy. Steric reasons for the geometrical preferences are discussed.