Five- and six-co-ordinate tertiary phosphine complexes of bis(diphenylphosphinodithioato)palladium(II)

Abstract

The interaction of Pd(S₂PPh₂)₂ with tertiary phosphines to give both 1 : 1 (for PPh₃, PEtPh₂, PMe₂Ph, and PEt₃) and 1 : 2 (for PMe₂Ph and PEt₃) adducts is described. l.r. spectra and molecular-weight evidence suggest that in the solid state, these are genuine five-and six-co-ordinate palladium(II) complexes respectively. Conversion between two five-co-ordinate isomers has been followed in the solid state by i.r. spectroscopy and tentative conclusions have been made about the stereochemistry of these isomers. In solution, i.r. evidence suggests that the 1 : 1 adducts may exist as a mixture of solvated square pyramidal species although the presence of a trigonal bipyramidal structure cannot be discounted. In solution, the 1 : 2 complexes rapidly dissociate to the 1 : 1 adducts and can be stabilised only by addition of excess of tertiary phosphine.