Development of a Synthetic Route to Unsymmetrical Triphosphine Ligands and an Investigation of Their Coordination Chemistry with Nickel and Palladium

Abstract

Chiral tridentate phosphines, R(2)P(CH(2))(3)PPh(CH(2))(2)PPh(2) where R = C(6)H(5), p-ClC(6)H(4), and p-FC(6)H(4), can be prepared from simple starting materials, (R(3)P, I(CH(2))(3)I, and Ph(2)P(CH(2))(2)PPh(2)), in a few stages involving phosphonium salts and phosphine oxides as intermediates. Crystalline diamagnetic complexes of nickel(II) and palladium(II) have been isolated. In solution these show first-order 12 line (31)P NMR spectra consistent with three nonequivalent phosphorus nuclei coupled to one another in a square planar geometry. A single X-ray crystallographic study of NiI(2){P(CH(2))(3)PPh(CH(2))(2)PPh(2)} showed that this was square pyramidal in the solid state with a weakly held apical iodo ligand.