Synthesis and properties of pentavalent antimony and bismuth fluorides

Properties of Sb^v and Bi^v fluorides and M^IIF₂-M^vF₅ (M^v ? Sb, Bi; M^II ? Mg, Ca, Sr, Ba), HalF₃-BiF₅ (Hal ? Cl, Br) systems have been studied. Only M_II(M^vF₆)₂ and HalF₂BiF₆] are shown to be formed in these systems. M_II(M^vF₆)₂ and HalF₂BiF₆] contain M^vF₆-octahedra in their crystal lattices. SbF₅ is found to be a stronger Lewis acid than BiF₅ and to be capable to substitute the latter in its fluoro complexes. BiF₅, in contrast to SbF₅, does not form polyfluoro anions (e.g.MF₁₁-etc.). The thermal stability of Sb_v and Bi_v fluorides and their transformations at high temperature were studied.