Synthesis, Structural Characterization, and Computational Study of the Strong Oxidant Salt [XeOTeF5][Sb(OTeF5)6]·SO2ClF
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abstract
The strong oxidant salt [XeOTeF(5)][Sb(OTeF(5))(6)].SO(2)ClF has been synthesized by reaction of stoichiometric amounts of Xe(OTeF(5))(2) and Sb(OTeF(5))(3) in SO(2)ClF solution at -78 degrees C and characterized in SO(2)ClF solution by low-temperature (17)O, (19)F, (121)Sb, (125)Te, and (129)Xe NMR spectroscopy, showing the Xe...O donor-acceptor bond XeOTeF(5)(+).SO(2)ClF adduct-cation to be labile at temperatures as low as -80 degrees C. The salt crystallizes from SO(2)ClF as [XeOTeF(5)][Sb(OTeF(5))(6)].SO(2)ClF, and the low-temperature crystal structure was obtained: triclinic, P, a = 9.7665(5) A, b = 9.9799(4) A, c = 18.5088(7) A, alpha = 89.293(2) degrees , beta = 82.726(2) degrees , gamma = 87.433(3) degrees , V = 1787.67(13) A(3), Z = 2, and R(1) = 0.0.0451 at -173 degrees C. Unlike MF(6)(-) in [XeF][MF(6)] (e.g., M = As, Sb, Bi) and [XeOTeF(5)][AsF(6)], the Sb(OTeF(5))(6)(-) anion is significantly less basic and does not interact with the coordinately unsaturated xenon(II) cation. Rather, the XeOTeF(5)(+) cation and weak Lewis base, SO(2)ClF, interact by coordination of an oxygen atom of SO(2)ClF to xenon [Xe...O, 2.471(5) A]. The XeOTeF(5)(+).SO(2)ClF adduct-cation has also been studied by low-temperature Raman spectroscopy, providing frequencies that have been assigned to adducted SO(2)ClF. The solid-state Raman spectra of XeOTeF(5)(+).SO(2)ClF and Sb(OTeF(5))(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 XeOTeF(5)(+).SO(2)ClF and related systems. The quantum mechanical calculations provided consistent trends for the relative strengths of the Xe...O donor-acceptor bond in XeOTeF(5)(+).SO(2)ClF and ion-pair bonds in [XeL][MF(6)] (L = F, OTeF(5); M = As, Sb), with the Xe...O bond of XeOTeF(5)(+).SO(2)ClF being the weakest in the series.
