The preparation and crystal structure of (β)6SbF3·5SbF5

Abstract

(β)6SbF₃·5SbF₅was prepared by the reduction of SbF₃·SbF₅ with a slight excess of phosphorus trifluoride relative to the stoicheiometric amount, in arsenic trifluoride solution. It was also prepared by the reduction of antimony pentafluoride in sulphur dioxide solution and a stoicheiometric quantity of iodine. The Raman spectrum of (β)6SbF₃·5SbF₅ is identical to that of a material designated SbF₅·SbF₃(B) by previous workers. A single-crystal X-ray diffraction study of (β) 6SbF₃·5SbF₅shows that it is monoclinic, space group P2₁/c with cell dimensions a= 11.638(1), b= 8.995(1), c= 16.723(2)Å, β= 106.81(1)°, and Z= 2. The structure was refined to a final R of 0.041 for 2 440 reflections. The structure consists of discrete Sb₆F₁₃⁵⁺ cations and SbF₆^– anions with cation-anion interactions. The cation can be viewed as being built of strongly interacting Sb₂F₅⁺ and SbF₂⁺ units. The geometries of the fluorine atoms about the various Sb^III species are described and discussed. The structure of (β)6SbF₃·5SbF₅ is similar to, but different from, (α) 6SbF₃·5SbF₅, previously prepared at high temperatures by the fluorination of antimony metal.