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E.H. Appelman B. Beagley D.W.J. Cruickshank A. Foord S. Rustad V. Ulbrecht 《Journal of Molecular Structure》1976,35(1):139-148
The molecular structure of FBrO3 has been studied by gas-phase electron diffraction. Least-squares refinements of the molecular geometry using fixed spectroscopic amplitudes revealed two geometrical minima. Initially, the amplitudes employed were derived from diagonal force fields obtained by spectroscopic least-squares refinements to fit observed and calculated wave numbers; for each geometry there are two spectroscopic minima. In the lowest geometrical minimum the wave number agreement is poor, however, the introduction of the ∠OBrO/∠FBrO interaction force constant removed the discrepancies; the resulting force field is F(Br-O) = 6.92 ± 0.02 mdyn Å?1F(Br-F) = 3.22 ± 0.03 mdyn Å?1, F(∠OBrO) = 1.06 ± 0.02 mdyn Å, F(∠FBrO) = 0.81 ± 0.03 mdyn Å, F(∠OBrO/∠FBrO) = ?0.19 ± 0.02 mdyn Å. In the corresponding geometrical minimum rg(Br-O) = 1.582 ± 0.001 Å, rg(Br-F) = 1.708 ± 0.003 Å, rα(∠OBrO) = 114.9 ± 0.3°, rα(∠FBrO) = 103.3 ± 0.3°. Perpendicular amplitude correction coefficients, calculated for each force field employed, were used throughout to relate the interatomic distances through the rα-structure. The geometries of the rαo- and re-structures are estimated. 相似文献
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Jack M. Williams M. A. Beno E. H. Appelman J. M. Capriotti F. Wudl E. Aharon-Shalom 《Molecular Crystals and Liquid Crystals》2013,570(1):675-682
Abstract We report the first crystallographic analysis, as a function of temperature, of a TMTSF derivative. Both (TMTSF)2(FSO3) and (TMTSF)2(BrO4) are isostructural (triclinic, with space group PI) with superconducting (TMTSF)2(ClO4). (TMTSF)2(FSO3) undergoes a metal-to-insulator transition at 86-90K as observed by microwave conductivity, D.C. conductivity, and magnetic susceptibility. The crystal structure contains 2-dimensional sheets of short Se-Se contacts in the molecular stacking direction and perpendicular to the stacking direction. The temperature dependent variations in these contact distances appear to be of special importance in determining the conduction properties of these materials, and are observed to change in a surprising manner when (TMTSF)2(FSO3) is cooled (298 → 123K). The homoatomic Se separations within each TMTSF molecule appear to increase slightly, but not significantly. At the same time the entire 2-dimensional sheet of intermolecular (intra- and interstack) Se-Se contacts between TMTSF molecules contract quite anisotropically, which results in an increase in “dimensionality” of the Se-Se network. Hence, an increase in electrical conduction, in the absence of insulating phenomena, over the temperature range 298 → 123K is not surprising. The intermolecular Se-Se contact distances in (TMTSF)2(BrO4) are significantly longer than in (TMTSF)2(FSO3) which suggests that the room temperature electrical conductivity of the (BrO4)? salt may be diminished compared to the (FSO3)? analogue. 相似文献
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The chemical reactions of hypofluorous acid with aromatic and olefinic substrates show considerable variety. Hypofluorous acid reacts with naphthalene to give 1-naphthol, 2-naphthol and 1,4-naphtho-quinone; with benzo[b]thiophen to give the 1,1-dioxide; with trans-stilbene to give threo-2-fluoro-1-hydroxy-1, 2-diphenylethane, benzophenone and diphenylacetaldehyde; and with cholesteryl acetate to give the two epoxides (α:β = 6.3:1) and two fluorohydrins (6β-fluoro-5β-o1 and 5α-fluoro-6β-o1). 相似文献
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Hoen R Leleu S Botman PN Appelman VA Feringa BL Hiemstra H Minnaard AJ van Maarseveen JH 《Organic & biomolecular chemistry》2006,4(4):613-615
A BICOL derived monodentate phosphoramidite ligand gives ee's up to 89% in the enantioselective Rh-catalysed hydrogenation of N-acyl dehydroalanine using water as the solvent. 相似文献
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P.A.G. OHare H.E. Flotow E.H. Appelman 《The Journal of chemical thermodynamics》1982,14(12):1191-1196
The low-temperature (5 to 310 K) heat capacity of cesium fluoroxysulfate, CsSO4F, has been measured by adiabatic calorimetry. At T = 298.15 K, the heat capacity Cpo(T) and standard entropy So(T) are (163.46±0.82) and (201.89±1.01) J · K?1 · mol?1, respectively. Based on an earlier measurement of the standard enthalpy of formation ΔHfo the Gibbs energy of formation ΔGfo(CsSO4F, c, 298.15 K) is calculated to be ?(877.6±1.6) kJ · mol?1. For the half-reaction: SO4F?(aq)+2H+(aq)+2e? = HSO4?(aq)+HF(aq), the standard electrode potential E at 298.15 K, is (2.47±0.01) V. 相似文献
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Angie?S?Mah Andrew?EH?Elia Geeta?Devgan Jason?Ptacek Mike?Schutkowski Michael?Snyder Michael?B?Yaffe Raymond?J?DeshaiesEmail author 《BMC biochemistry》2005,6(1):22