Synthesis and structure of four- and five-coordinated gaseous oxohalides of molybdenum(VI) and tungsten(VI)
About: This article is published in Inorganic Chemistry.The article was published on 1968-12-01. It has received 43 citations till now. The article focuses on the topics: Molybdenum & Tungsten.
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TL;DR: The tri(alkoxy)siloxy complexes MO[OSi(OtBu)3]4 (1, M = Mo and 2, W = W) were obtained from MOCl4 and LiO2Cl2(DME) as discussed by the authors.
Abstract: The tri(alkoxy)siloxy complexes MO[OSi(OtBu)3]4 (1, M = Mo and 2, M = W) were prepared from MOCl4 and LiOSi(OtBu)3. Similarly, reactions of MO2Cl2(DME) with LiOSi(OtBu)3 afforded the new siloxide complexes MO2[OSi(OtBu)3]2 (3, M = Mo and 4, M = W), which are themally unstable at ambient temperature. More stable compounds were obtained by the crystallizations of 3 and 4 in a coordinating solvent, to form the ether adducts MoO2[OSi(OtBu)3]2(THF) (3a) and WO2[OSi(OtBu)3]2(DME) (4a). These compounds serve as soluble models for isolated molybdenum or tungsten atoms on a silica surface and were characterized by 1H, 13C, 29Si, 95Mo, and 183W NMR, FT-Raman, FT-IR, and UV-vis spectroscopies. Compounds 1, 2, 3a, and 4a were used to prepare metal-oxide silica composites via the thermolytic molecular precursor method. The xerogels obtained from the thermolyses of 1, 2, 3a, and 4a in toluene contained mesoporosity with surface areas of 10, 230, 106, and 270 m2 g-1, respectively. Despite the high surface areas for most samples, these xerogels contain MO3 domains. Complexes 1 and 2 were also used to introduce molybdenum and tungsten sites, respectively, onto mesoporous SBA-15 silica via displacement of the -OSi(OtBu)3 ligand for a siloxyl group from the silica surface. All molybdenum- and tungsten-containing systems were tested as catalysts for the epoxidation of cyclohexene using tert-butyl hydroperoxide (TBHP) or aqueous H2O2 as the oxidant.
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09 Mar 2007
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TL;DR: In this paper, the infrared spectrum of CrO 2 Cl 2, a deep red liquid, has been measured from 120-3000 cm −1, where six Raman lines have been obtained by excitation with the D -lines of potassium.
69 citations
TL;DR: In this paper, the infrared spectrum of gaseous chromyl fluoride and chromyl chloride has been investigated and the observed transitions have been assigned on the basis of a tetrahedral model of C2v symmetry.
Abstract: The infrared absorption spectra of gaseous chromyl fluoride and gaseous chromyl chloride have been investigated. The region investigated for chromyl fluoride was 2 to 36 μ while that for chromyl chloride was 2 to 25 μ. Six fundamental and nineteen first overtone or binary combination bands have been observed in the spectrum of chromyl fluoride, the fundamental bands being located at 274, 304, 727, 789, 1006, and 1016 cm—1. The observed transitions have been assigned on the basis of a tetrahedral model of C2v symmetry. From the observed spectrum it was possible to estimate the probable positions of the three remaining fundamental bands. The observed spectrum of chromyl chloride included four fundamental bands located at 475, 499, 990, and 1000 cm—1 and one first overtone or binary combination band located at 1980 cm—1.
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TL;DR: In this article, the infrared absorption spectra in the range 4000 to 400/cm of the vapors above liquid H2SO4, 1:1 H2-SO4 D2SO 4, and D2 SO4 were measured and assigned to the respective gaseous molecules as well as equilibrium concentrations of SO3.
Abstract: : The infrared absorption spectra in the range 4000 to 400/cm of the vapors above liquid H2SO4, 1:1 H2-SO4 D2SO4, and D2SO4 were measured and assigned to the respective gaseous molecules as well as equilibrium concentrations of SO3. SO2 was observed as a decomposition product. Assignment of the frequencies to the normal modes was made using correlations with the related near-tetrahedral molecules X-SO2-Y and with spectra of the condensed phases. Some frequencies are predicted for H2CrO4 and for unassociated gaseous chlorosulfonic acid. (Author)
58 citations