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Properties of Chalcogene-Chalcogene Bonds. XII. Reversible Telluration of Tetraisopropyldiphosphane, Stabilisation of Tellurobis(diisopropylphosphane) as Tetracarbonylchromium Complex Tetraisopropyldiphosphane 1 reacts with elemental tellurium by tellurium atom insertion to give tellurobis(diisopropylphosphane) 2. 2 is also available from sodium telluride with chlorodiisopropyl phosphane. lH, l3C, 3lP and l25Te n.m.r. spectra confirm that in solution 2 is in an equilibrium with the educt 1 and elemental tellurium. Reaction of this equilibrium mixture with tetracarbonyl(norbornadiene)chromium(0) provides tetracarbonyl[tellurobis(diisopropylphosphane)]-chromium(0) 3. 3 was isolated in pure state as stable compound; different from 2,3 does not suffer from loss of tellurium at room temperature. 相似文献
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Barry SJ Carr RM Lane SJ Leavens WJ Monté S Waterhouse I 《Rapid communications in mass spectrometry : RCM》2003,17(6):603-620
A simple method has been developed for the pre-column derivatisation of low molecular weight primary and secondary amines and carboxylic acids using quaternary nitrogen compounds to enhance their detection by liquid chromatography/electrospray ionisation mass spectrometry (LC/ESI-MS). The synthesis of seven novel quaternary nitrogen reagents is described. The derivatives are designed to be relatively small molecules to avoid some of the steric hindrance problems that may be associated with larger derivatisation reagents. The compounds have amine and carboxylic acid functional groups with which to derivatise carboxylic acids and amines, respectively. Two of the compounds contain a bromine atom in order to assess the advantages of a bromine isotope pattern in the mass spectra. This acts as a simple marker for derivatisation and enables data processing by cluster analysis.Activation of the carboxylic acid group was achieved by the use of either 1-chloro-4-methylpyridinium iodide (CMPI) or the more reactive 1-fluoro-4-methylpyridinium p-toluenesulphonate (FMP).1 Using both of these active reagents, the degree of nucleophilic substitution was investigated for the derivatisation of a variety of small molecules. Whilst giving some increase in the ESI-MS response for the derivatised compounds, the FMP itself acted as a derivatising reagent in a competing reaction. In the light of this finding, FMP was reacted with the test compounds separately and gave positive results as a derivatising reagent. Detection of the 'pre-charged' derivatives of amines and carboxylic acids by LC/ESI-MS was investigated with respect to their ESI response and chromatography. 相似文献
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119mSn Mössbauer data for a series of base-stabilized, intermolecularly associated tin(II) compounds ith O, Cl, P and As atoms bonded to tin are compared with isomer shifts (IS) and quadrupole splittings (QS) of their stannio complex derivatives with Cr, Mo and W carbonyls. Coordination at the tin lone-pair atom decreases IS to ca. 2.1 ± 0.2 mm s?1 and increases the QS. QS values reflect the highly associated nature of the complexes (CO)5MSn(Cl)E(t-Bu)2 (M Cr, W; E P, As) which are bridged through μ-E(t-Bu)2 groups. 相似文献
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Sandra J. Atkinson Heather E. Robertson Margit Hölbling Wolf-Walther du Mont Cristina Mitrofan Karl Hassler Sarah L. Masters 《Structural chemistry》2013,24(3):851-857
The gas-phase molecular structures of a series of halogen-substituted disilanes [X3SiSiMe3 (X = H, F, Cl and Br)], 1,1,1-trimethyldisilane (H3SiSiMe3), 1,1,1-trifluoro-2,2,2-trimethyldisilane (F3SiSiMe3), 1,1,1-trichloro-2,2,2-trimethyldisilane (Cl3SiSiMe3) and 1,1,1-tribromo-2,2,2-trimethyldisilane (Br3SiSiMe3), have been determined in the gas phase by electron diffraction. Ab initio calculations at the HF and MP2 level were used to support the experimental investigation using the SARACEN method. All of the investigated structures were determined to adopt a staggered structure with C 3v symmetry. The effect of substitution on the Si–Si bond and the Si–Si–X bond angle was investigated and these results were compared to results obtained from a recent study of halogen-substituted disilanes [X3SiSiXMe2 (X = F, Cl, Br and I)] to consider the effect of the methyl groups on the substituted disilanes. 相似文献
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2,3-Di-tert-butyl-1-telluradiphosphirane and related Phosphorus—Tellurium Heterocycles 2,3-Di-tert-butyl-1-telluradiphosphirane was isolated in pure state by trap to trap condensation after reaction of 1,2-Di-tert-butyl-1,2-dichlorodiphosphane with sodium telluride in pentane suspension. The telluradiphosphirane and other P? Te heterocycles (t-BuP)nTem (n = 2, m = 1; n = 3, m = 1,2; n = 4, m = 1,2) are formed from 1,2-Di-tert-butyl-1,2-dichlorodiphosphane or tert-butyldichlorophosphane with bis(trimethylsilyl)telluride and from the reaction of tert-butylbis(trimethylsilyl)phosphane with elemental tellurium. The proposed structures of the P? Te heterocycles are based on 31P- and 125Te-n.m.r. and MS data 相似文献