ABSTRACT
The new [N(CH(3))(4)][WSF(5)] salt was synthesized by two preparative methods: (a) by reaction of WSF(4) with [N(CH(3))(4)][F] in CH(3)CN and (b) directly from WF(6) using the new sulfide-transfer reagent [N(CH(3))(4)][SSi(CH(3))(3)]. The [N(CH(3))(4)][WSF(5)] salt was characterized by Raman, IR, and (19)F NMR spectroscopy and [N(CH(3))(4)][WSF(5)]·CH(3)CN by X-ray crystallography. The reaction of WSF(4) with half an aliquot of [N(CH(3))(4)][F] yielded [N(CH(3))(4)][W(2)S(2)F(9)], which was characterized by Raman and (19)F NMR spectroscopy and by X-ray crystallography. The WSF(5)(-) and W(2)S(2)F(9)(-) anions were studied by density functional theory calculations. The novel [W(2)OSF(9)](-) anion was observed by (19)F NMR spectroscopy in a CH(3)CN solution of WOF(4) and WSF(5)(-), as well as CH(3)CN solutions of WSF(4) and WOF(5)(-).
ABSTRACT
Molybdenum sulfide tetrafluoride was synthesized from MoF(6) and S(Si(CH(3))(3))(2) in CFCl(3) at low temperature and was fully characterized by Raman, infrared, and (19)F NMR spectroscopy and by X-ray crystallography. The crystal structure revealed that MoSF(4) forms infinite fluorine-bridged chains. Quantum-chemical calculations using B3LYP and PBE1PBE methods were used to calculate the gas-phase geometry and vibrational frequencies of monomeric MoSF(4) and (MoSF(4))(3)F(-). The vibrational frequencies of (MoSF(4))(3)F(-) have been used in the assignment of the vibrational spectra of solid MoSF(4). Natural bond order analyses were carried out for monomeric MoSF(4) and, for comparison, for WSF(4).
ABSTRACT
A new and improved synthetic route to WSF(4) was developed from the reaction of WF(6) and Sb(2)S(3) in anhydrous HF. Tungsten sulfide tetrafluoride was characterized by Raman and (19)F NMR spectroscopy for the first time in HF solvent. Both studies provided evidence for its monomeric form in HF solution. In the solid state, WSF(4) was also characterized by Raman and infrared spectroscopy. The WSF(4) x CH(3)CN adduct was prepared from WSF(4) and CH(3)CN in anhydrous HF solvent and by the direct combination of WSF(4) with excess CH(3)CN, and was characterized by Raman and infrared spectroscopy in the solid state and (19)F NMR spectroscopy in CH(3)CN solution. The crystal structure of WSF(4) x CH(3)CN was obtained and showed that CH(3)CN coordinates to W in an end-on fashion and trans to the W-S bond. Quantum-chemical calculations using B3LYP and PBE1PBE methods were used to calculate the gas-phase geometries and vibrational frequencies of WSF(4) and WSF(4) x CH(3)CN.
ABSTRACT
The coordination compounds [Mg(XeF(2))(2)][AsF(6)](2), [Mg(XeF(2))(4)][AsF(6)](2), [Ca(XeF(2))(2.5)][AsF(6)](2), [Ba(XeF(2))(3)][AsF(6)](2), and [Ba(XeF(2))(5)][AsF(60](2) were characterized by solid-state (19)F and (129)Xe magic-angle spinning NMR spectroscopy. The (19)F and (129)Xe NMR data of [Mg(XeF(2))(2)][AsF(6)](2), [Mg(XeF(2)(4)][AsF(6)](2), and [Ca(XeF(2))(2.5)][AsF(6)](2) were correlated with the previously determined crystal structures. The isotropic (19)F chemical shifts and (1)J((129)Xe-(19)F) coupling constants were used to distinguish the terminal and bridging coordination modes of XeF(2). Chemical-shift and coupling-constant calculations for [Mg(XeF(2))(4)][AsF(6)](2) confirmed the assignment of terminal and bridging chemical-shift and coupling-constant ranges. The NMR spectroscopic data of [Ba(XeF(2))(3)][AsF(6)](2) and [Ba(XeF(2))(5)][AsF(6)](2) indicate the absence of any terminal XeF(2) ligands, which was verified for [Ba(XeF(2))(5)][AsF(6)](2) by its X-ray crystal structure. The adduct [Ba(XeF(2))(5)][AsF(6)](2) crystallizes in the space group Fmmm, with a = 11.6604(14) Angstrom, b = 13.658(2) Angstrom, c = 13.7802(17) Angstrom, V = 2194.5(5) Angstrom(3) at -73 degrees C, Z = 4, and R = 0.0350 and contains two crystallographically independent bridging XeF(2) molecules and one nonligating XeF(2) molecule. The AsF(6-) anions in [Mg(XeF(2))(4)][AsF(6)](2), [Ca(XeF(2))(2.5)][AsF(6)](2), [Ba(XeF(2))(3)][AsF(6)](2), and [Ba(XeF(2))(5)][AsF(6)](2) were shown to be fluxional with the fluorines-on-arsenic being equivalent on the NMR time scale, emulating perfectly octahedral anion symmetry.
