Fluoride crystal structures. Part 34. Antimony pentafluoride–iodine trifluoride dioxide

Abstract

The structure of the title adduct has been determined by the heavy-atom method from 1 451 diffractometer reflections and refined by full-matrix least-squares methods to R 0.074. Crystals are monoclinic, space group P2₁/c, with unit-cell dimensions a= 5.72(1), b= 9.96(1), c= 12.56(2)Å, β= 101.7(2)°. The solid adduct exists as dimers with two antimony and two iodine atoms at the corners of a rhombus, linked by asymmetric, angular oxygen bridges, with Sb–O 2.05 and I–O 1.80 Å. Both the SbF₄O₂ and IF₄O₄ units have distorted octahedral geometries with cis oxygen bridges, and with a greater distortion in the antimony unit. This can be correlated with a contribution to the structure from the ionic form [SbF₄]⁺[IF₄O₂]^–. The adduct has a very similar structure to pentafluorides typified by RuF₅, based on an approximate hexagonal close-packing of the light atoms.