Synthesis, structural characterization, and computational study of the strong oxidant salt [XeOTeF5][Sb(OTeF5)6]•SO2CIF

The strong oxidant salt [XeOTeF5][Sb(OTeF5)(6)](SO2CIF)-S-. has been synthesized by reaction of stoichiometric amounts of Xe(OTeF5)(2) and Sb(OTeF5)(3) in SO2CIF solution at -78 degreesC and characterized in SO2CIF solution by low-temperature O-17, F-19, Sb-121, Te-125, and Xe-129 NMR spectroscopy, showing the (XeO)-O-... donor-acceptor bond XeOTeF5+.SO2CIF adduct-cation to be labile at temperatures as low as -80 degreesC. The salt crystallizes from SO2CIF as [XeOTeF5][Sb(OTeF5)(6)](SO2CIF)-S-., and the low-temperature crystal structure was obtained: triclinic, P (1) over bar, a = 9.7665(5) Angstrom, b = 9.9799(4) Angstrom, c = 18.5088(7) Angstrom, alpha = 89.293(2)degrees, beta = 82.726(2)degrees, gamma = 87.433(3)degrees, V = 1787.67(13) Angstrom(3), Z = 2, and R-1 = 0.0.0451 at -173 degreesC. Unlike MF6- in [XeF][MF6] (e.g., M = As, Sb, Bi) and [XeOTeF5][AsF6], the Sb(OTeF5)(6)(-) anion is significantly less basic and does not interact with the coordinately unsaturated xenon(II) cation. Rather, the XeOTeF5+ cation and weak Lewis base, SO2CIF, interact by coordination of an oxygen atom of SO2CIF to xenon [(XeO)-O-..., 2.471(5) Angstrom]. The XeOTeF5+.SO2ClF adduct-cation has also been studied by low-temperature Raman spectroscopy, providing frequencies that have been assigned to adducted SO2CIF. The solid-state Raman spectra of XeOTeF5+.SO2CIF and Sb(OTeF5)(6)(-) have been assigned with the aid of electronic structure calculations. In addition to optimized geometries and vibrational frequencies, theoretical data, including gas-phase donor-acceptor bond energies, natural bond orbital (NBO) analyses, and topological analyses based on electron localization functions (ELF), provide descriptions of the bonding in XeOTeF5+.SO2CIF and related systems. The quantum mechanical calculations provided consistent trends for the relative strengths of the (XeO)-O-... donor-acceptor bond in XeOTeF5+. SO2CIF and ion-pair bonds in [XeL][MF6] (L = F, OTeF5; M = As, Sb), with the (XeO)-O-... bond of XeOTeF5+.SO2CIF being the weakest in the series.