Fluoride crystal structures. Part XXI. Trifluorotellurium(IV)µ-fluorobis[pentafluoroantimonate(V)]

Abstract

The interaction of tellurium tetrafluoride and antimony pentafluoride gives the title compound as a minor product. Crystals are monoclinic, space group P2₁/c, a= 7·48 ± 0·01, b= 14·29 ± 0·02, c= 9·72 ± 0·01 Å, β= 91·0°± 0·2°. The structure was solved by Patterson and Fourier methods and refined by three-dimensional least-squares methods to R 0·095 for 824 reflections measured photographically. Although the atomic arrangement is consistent with the ionic formulation [TeF₃]⁺[Sb₂F₁₁]^– there is considerable interaction between the ions through fluorine bridging. The cation has C_3v symmetry, with a mean Te–F distance of 1·84 Å, and there are three long contacts of 2·54, 2·55, and 2·69 Å to bridging fluorine atoms to give a much distorted octahedral co-ordination for tellurium, very similar to that found for selenium in [SeF₃]⁺[Nb₂F₁₁]^–.