Interaction between uranium tetrafluoride oxide and antimony pentafluoride; fluorine-19 nuclear magnetic resonance investigations in solution; preparation and characterization of the adducts UF4O·nSbF5(n= 1–3) and crystal structure of UF4O·2SbF5

Abstract

The adducts UF₄O·nSbF₅(n= 1–3) have been obtained as yellow-orange solids from the reaction of UF₄O with SbF₅ in SbF₅ or HF solvents. A ¹⁹F n.m.r. study has helped explain the nature of the interaction taking place in solution. The solid adducts have been characterized by observation of reaction stoicheiometries, chemical analysis, and vibrational spectra. An X-ray diffraction study has shown that crystals of UF₄O·2SbF₅ are monoclinic, space group P2₁/c, with unit-cell dimensions a= 7.864(16), b= 14.704(8), c= 9.980(8)Å, β= 99.8(1)°, and Z= 4. The structure has been refined by three-dimensional least-squares methods to R= 0.045 6 for 1 168 reflections. The structure is best regarded as a fluorine-bridged network of UF₄O and SbF₅ molecules in which the antimony is surrounded by a distorted octahedron of fluorine atoms and the uranium by a pentagonal-bipyramidal array of six fluorines and one oxygen. It is suggested that the structures of the 1 : 1 and 1 : 3 adducts will be related.