DEVELOPMENT OF A SYNTHETIC ROUTE TO UNSYMMETRICAL TRIPHOSPHINE LIGANDS AND AN INVESTIGATION OF THEIR COORDINATION CHEMISTRY WITH NICKEL ANDPALLADIUM

Chiral tridentate phosphines, R(2)P(CH2)(3)PPh(CH2)(2)PPh(2) where E = C6H5, p-ClC6H4, and p-FC6H4, can be prepared from simple starting mat erials, (R(3)P, I(CH2)(3)I, and Ph(2)P(CH2)(2)PPh(2)), in a few stages involving phosphonium salts and phosphine oxides as intermediates. Cr ystalline diamagnetic complexes of nickel(II) and palladium(II) have b een isolated. In solution these show first-order 12 line P-31 NMR spec tra consistent with three nonequivalent phosphorus nuclei coupled to o ne another in a square planar geometry. A single X-ray crystallographi c study of NiI2{P(CH2)(3)PPh(CH2)(2)PPh(2)} showed that this was squar e pyramidal in the solid state with a weakly held apical iodo ligand.