Reaction of GeCl4 with some phosphorus and arsenic donor ligands; crystal structures of the germanium(II) complex [Bun3PCl][GeCl3] and the germanium(IV) complex GeCl4(AsMe3)2, the first reported example of a tertiary arsine complex of GeIV

Abstract

The tertiary phosphines PR₃ {R₃ = Me₃, Et₃, Prⁿ₃, Buⁿ₃, Bu^t₃, (C₆H₁₁)₃, [2,6-(CH₃O)₂C₆H₃]₃, [2,4,6-(CH₃O)₃C₆H₂]₃, (C₆H₅CH₂)₃, (Me₂N)₃, (Et₂N)₃, (Prⁿ₂N)₃, Ph₂Et or Ph₃} and tertiary arsines AsR₃ (R = Ph or Me) have been treated with germanium tetrachloride in both a 1∶1 and 2∶1 stoichiometric ratio in diethyl ether solution. In the tertiary phosphine reactions a redox reaction occurs to produce the ionic germanium(II) complexes [R₃PCl][GeCl₃] in near to quantitative yield, the chlorophosphinium cation being identified by ³¹P-{H} NMR spectroscopy. No evidence for the previously reported molecular germanium(IV) adducts GeCl₄(PR₃)₂ was observed, apart from the possible assignments of minor peaks in the ³¹P-{H} NMR spectrum for some of the products. The crystal structure of [Buⁿ₃PCl][GeCl₃] revealed no interaction between the cation and anion, in direct contrast to the only other reported complex of this stoichiometry, [Prⁱ₃PBr][GeBr₃]. No reaction was observed between PPh₃ and GeCl₄. The reaction of AsMe₃ with GeCl₄ in both a 1∶1 and 2∶1 stoichiometric ratio produced the molecular trans-octahedral germanium(IV) complex, GeCl₄(AsMe₃)₂, the first crystallographically characterised germanium(IV) tertiary arsine complex [d(Ge–As) = 2.472(1) Å]. No reaction occurred between GeCl₄ and AsPh₃.