Fluoride ion donor properties of UF2O2; preparation and characterization of the adducts UF2O2·nSbF5(n= 2 or 3) and crystal structure of UF2O23SbF5
Abstract
The adducts UF2O2·nSbF5(n= 2 or 3) have been obtained as pale green and pale yellow-green solids respectively from the reaction of UF2O2 with SbF5 in HF solvent. The solid adducts have been characterized by observation of reaction stoicheiometries, chemical analyses, and vibrational spectra. An X-ray diffraction study has shown that crystals of UF2O2·3SbF5 are monoclinic, space group P21/n, with unit-cell dimensions a= 11.040(7), b= 12.438(12), c= 12.147(8)Å, β= 111.16(20)°, and Z= 4. The structure has been refined by three-dimensional least-squares methods to R= 0.0773 for 1 613 reflections. The structure is best regarded as a fluorine-bridged network of UF2O2 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 five fluorines and two oxygens. Two of the uranium–fluorine distances are long and this means that the structure can also be described in terms of zigzag chains of UO2 groups fluorine-bridged to SbF6 units with Sb2F11 side-chains attached to the uraniums.