Complexes of germanium(iv) fluoride with phosphane ligands: structural and spectroscopic authentication of germanium(iv) phosphane complexes

Abstract

The first phosphane complexes of germanium(IV) fluoride, trans-[GeF4(PR3)2] (R = Me or Ph) and cis-[GeF4(diphosphane)] (diphosphane = R2P(CH2)2PR2, R = Me, Et, Ph or Cy; o-C6H4(PR2)2, R = Me or Ph) have been prepared from [GeF4(MeCN)2] and the ligands in dry CH2Cl2 and characterised by microanalysis, IR, Raman, 1H, 19F{1H} and 31P{1H} NMR spectroscopy. The crystal structures of [GeF4(diphosphane)] (diphosphane = Ph2P(CH2)2PPh2 and o-C6H4(PMe2)2) have been determined and show the expected cis octahedral geometries. In anhydrous CH2Cl2 solution the complexes are slowly converted into the corresponding phosphane oxide adducts by dry O2. The apparently contradictory literature on the reaction of GeCl4 with phosphanes is clarified. The complexes trans-[GeCl4(AsR3)2] (R = Me or Et) are obtained from GeCl4 and AsR3 either without solvent or in CH2Cl2, and the structures of trans-[GeCl4(AsEt3)2] and Et3AsCl2 determined. Unexpectedly, the complexes of GeF4 with arsane ligands are very unstable and have not been isolated in a pure state. The behaviour of the germanium(IV) halides towards phosphane and arsane ligands are compared with the corresponding silicon(IV) and tin(IV) systems