SYNTHESIS AND CHARACTERIZATION OF PALLADIUM(II) AND PLATINUM(II) COMPLEXES CONTAINING MONODENTATE PHOSPHORUS DONATING OR CHELATING 2-(DIMETHYLPHOSPHINO)PYRIDINE (PME2PY)

The complexes [MX2(PMe2py-P)2] (M = Pd(II), Pt(II); X = Cl, Br, and I) have been synthesized and characterized both in the solid state and in solution by their infrared and H-1, C-13, and P-31 NMR spectra, in addition to an X-ray crystallographic analysis of cis-[PdCl2(PMe2py-P)2]. The latter complex exists as a cis-trans equilibrium mixture in solution, while only the cis isomer has been isolated in the solid state. The [PdBr2(PMe2py-P)2] complex which has been isolated as the trans isomer shows also the same isomerization in solution, in contrast to [PdBr2(PMe2Ph)2] which exists only as the trans isomer both in the solid state and in solution. Furthermore, PMe2py has been found to have the ability for chelation via the nitrogen and phosphorus atoms to make a four-membered chelate ring. The chelate ring in the complexes [PdX(PMe2py)2]Y (X = Cl, Br, and I; Y = ClO4-, PF6-) has been confirmed by infrared spectra and X-ray analysis of cis(P,P)-[PdCl(PMe2py-P,N)(PMe2py-P)]ClO4. This is the first example in which PMe2py is acting as a chelating ligand.