The preparation and crystal structure of 5SbF3·3SbF5
Abstract
5SbF3·3SbF5 was prepared by the reduction of SbF3·SbF5 or SbF5 with a stoicheiometric amount of PF3 in arsenic trifluoride solution. A single-crystal X-ray diffraction study of 5SbF3·SbF5 shows that it is orthorhombic, space group Pnma with cell dimensions, a= 19.187(9), b= 15.890(2), c= 15.713(3)Å, and Z= 8. The structure was refined to a final R of 0.057 for 3 718 reflections. The structure consists of a three-dimensional cross-linked polymeric (Sb5F12)n3n+ cation and SbF3– anions with significant cation–anion interactions. The polymeric cation can be viewed as being built of strongly interacting Sb2F5+, SbF3, and Sb2F33+ units. The various configurations of Sb2F5+ cations are described and discussed. The planar eclipsed Sb2F33+ cation has not been observed in other binary fluorides of antimony. The geometries of the fluorine atoms in the several co-ordination spheres about the various antimony(III) species are described. A rationale is advanced for the existence of a variety of polymeric antimony(III) fluorocations formed between SbF3 and SbF5, in contrast to AsF3 and SbF5 which form an adduct that can be described as AsF2+SbF6–. The Raman spectrum of 5SbF3·3SbF5 is reported.