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

The first phosphane complexes of germanium(IV) fluoride, trans-[GeF4(PR3)(2)] (R = Me or Ph) and cis-[GeF4(diphosphane)] (diphosphane = R2P(CH2)(2)PR2, 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, H-1, F-19{H-1} and P-31{H-1} NMR spectroscopy. The crystal structures of [GeF4(diphosphane)] (diphosphane = Ph2P(CH2)(2)PPh2 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 O-2. 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.