Synthesis and coordination properties of palladium(II) and platinum(II) complexes with phosphonated triphenylphosphine derivatives

Two triphenylphosphine derivatives, diethyl [4-(diphenylphosphanyl)benzyl]phosphonate (3a) and tetraethyl {[5-(diphenylphosphanyl)-1,3-phenylene]dimethylene}bis(phosphonate) (3b), and also the corresponding free acids 4a and 4b were prepared. These ligands were characterized by 1H, 13C and 31P NMR spectroscopy and mass spectrometry. A full set of their Pd(II) and Pt(II) complexes of the general formula [MCl2L2] and one dinuclear complex trans-[Pd2Cl4(3a)2] were synthesized and their isomerization behaviour in solution was studied. The complexes were characterized by 1H, 13C, 31P and 195Pt NMR spectroscopy, mass spectrometry and far-IR spectroscopy. The X-ray structures of all complexes with 3a or 3b have usual slightly distorted square-planar geometry on the metal ion. Salts of phosphonic acids 4a and 4b and their complexes are freely soluble in aqueous solution; therefore, they can be potentially useful in aqueous or biphasic catalysis.