Recent achievements in the synthesis and characterization of metal hexafluorantimonates and hexafluoroaurates

摘要

The efforts to prepare new MSbF_6/MSb_2F_11 (A = In,Cu,Au,Hg) compounds were partly successful.Reaction between InBF_4 and excess SbF_5 in anhydrous hydrogen fluoride (aHF) yields a mixture of InF_3-3SbF_5 and unidentified SbF_3xSbF_5.The attempts to synthesize MSbFg/ MSb_2F]! salts (A = Au,Hg) by controlled reduction of Au(SbF_6)_2 or Hg(SbF_6)_2 solutions in aHF/SbF5 by elemental hydrogen,resulted in the precipitation of metallic Au or Hg_2(Sb_2F_n)_2.In the reaction of metallic Cu and deficit SbF_5,the synthesis of CuSbF_6 was achieved.CuSbF_6,like CuAsF_6,is a rare example of a Cu(I) compound in a pure fluorine environment.Vibrational spectra of M(H) hexafluoroantimonates (M = Ni,Fe,Co,Cu,Cr,Pd,Ag) were reinvestigated.It was found that many of them originally assigned to M(SbF6)2 compounds,belong to their mixtures with oxonium salts H_3OM(SbF_6)_3,H_3OSbF_6,and/or H_3OSb_2F_(11).Reactions were studied between MF2/2AuF3 (M = Ni,Cu,Ag,Zn,Cd and Hg) and KrF_2 or UV-irradiated elemental fluorine in aHF as solvent at room temperature.On the basis of mass balances,Raman spectroscopy and X-ray powder diffraction analysis it can be concluded that the isolated solids have structures that can be considered in terms of an M(AuF_6)_2 formulation.Previously reported syntheses and characterization of M(AuF_6)_2 (M = Mg,Ca,Sr,Ba) were reinvestigated.In the case of M = Ba two different AuF_6- salts were isolated.Raman spectra of the majority of synthesized metal hexafluoroaurates (M = Ni,Cu,Ag,Zn,Cd,Hg,Mg and Ca) show more bands than expected for regular AuF_6~- anion,indicating that the salts obtained exhibit relatively strong cation-anion interactions.The Raman spectra of the remaining Sr and Ba salts show the presence of more regular AuF~6~- octahedra,indicating weak cation-anion interactions.