Structural characterization of hypervalent fluoride and oxofluoride derivatives of xenon and tellurium and iodine

The study of fluoro- and oxofluoro-anions and cations having coordination numbers higher than six has been of particular interest and is exemplified by the fluoride ion donor and electron pair acceptor properties of the oxofluorides of xenon. The X-ray crystal structure of XeOF3+SbF6− has been determined. The XeOF3+ cation is shown to have two fluorine bridges to neighboring SbF6− anions, resulting in an AX6E VSEPR arrangement around xenon in the solid state. The solution 17O NMR spectrum along with the 17O/18O isotope shift ratio in the 129Xe spectrum of the XeOF3+ cation have also been obtained. The fluoride ion donor properties of XeOF2 and the formation of the XeOF+ cation are also discussed. The electron pair acceptor properties of XeOF4, XeOF2 and XeO3 in the presence of nitrogen bases have been investigated by NMR spectroscopy. The XeOF4·CH3CN adduct has been isolated as a crystalline solid and its structure also appears to be best represented as a distorted octahedral (AX6E) arrangement.In collaboration with Dr. K.O. Christe and Dr. W.W. Wilson (Rockwell International), a number of hypervalent anions having coordination numbers exceeding six have been prepared and characterized. The IOF6− anion has been characterized as its N(CH3)4+ salt by X-ray crystallography, vibrational spectroscopy and in solution by NMR spectroscopy. The X-ray structure shows that the anion is distorted from C5v point symmetry by means of a puckering of the five fluorines in its equatorial plane. The structures of the N(CH3)4+ salts of the TeOF62−, XeOF5−, XeF7− and TeF7− anions will also be described.The Lewis acid properties of XeF+ and XeOTeF5+ have been investigated in the presence of the nitrogen base F5TeNH2. The novel XeN bonded F5TeN(H)Xe+ and F5TeN(H)XeNCH+ cations have been synthesized in anhydrous HF and characterized by 1H, 15N, 19F, 125Te and 129Xe NMR spectroscopy.