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991.
Christoph Peters Hendrik Disteldorf Evelyn Fuchs Stefan Werner Stefanie Stutzmann Joachim Bruckmann Carl Krüger Paul Binger Heinrich Heydt Manfred Regitz 《European journal of organic chemistry》2001,2001(18):3425-3435
Ethylene, various monosubstituted alkenes (acrylic acid derivatives, styrene), as well as some selected disubstituted alkenes (maleic acid derivatives, fumaric acid derivatives, norbornene, cyclopentadiene) undergo Diels−Alder reactions with the 1,3,5-triphosphabenzenes 1 under mild conditions to furnish the dihydrotriphosphabarrelenes 9 , 11a − c , 13a − e , 15a − d , 17a , b , and 24 . The monoadduct 26 as well as the diadducts 27 and 28 are isolated following the reaction with norbornadiene. Cyclopropene is the only alkene to undergo a Diels−Alder/homo Diels−Alder reaction sequence to afford the hexacyclic system 20 . 相似文献
992.
The cation cis-[Ir(η2-C8H14)2(acetone)2]+, which is generated in situ from [Ir(μ-Cl)(η2-C8H14)2]2 ( 1 ) and AgPF6 in acetone, reacts with butadiene at room temperature to give the five-coordinate complex [Ir(s-cis-η4-C4H6)2(η2-C8H14)]PF6 ( 3 ). The cyclooctene ligand of 3 is only weakly coordinated and easily displaced by PiPr3, AsiPr3 and SbiPr3 to afford the compounds [Ir(s-cis-η4-C4H6)2(EiPr3)]PF6 ( 5−7 ) in excellent yields. Alternatively, 5−7 can be prepared from [IrCl(s-cis-η4-C4H6)2] ( 4 ) by stepwise treatment with AgPF6 and EiPr3 (E = P, As, Sb). The X-ray crystal structure analysis of 5 revealed a square-pyramidal geometry of the cation with the phosphane ligand in the apical position. 相似文献
993.
994.
995.
CuAl2F2(Si2O7) has been prepared by hydrothermal synthesis and its crystal structure was determined by single crystal X‐ray diffraction: space group Pnma, a = 8.8697(9), b = 14.084(2), c = 4.7553(5) Å, wR2 = 0.056, R = 0.022. Cu2+ shows elongated square pyramidal coordination. Edge‐ and corner‐sharing [AlO4F2] octahedra with fluorine atoms in cis position form layers parallel to the ac plane. Along b these layers are linked by Si2O7 groups to form a three‐dimensional framework [Al2F2(Si2O7]2–. In addition, the [CuO5] pyramides connect two Al octahedra of neighbouring layers. The crystal structure is discussed as a derivative from topaz structure. The modular (or polysomatic) approach is used for this purpose, and for modelling hypothetical related compounds. 相似文献
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998.
Matthias Roßberg Werner Strube Jrg Wollbrandt Eberhard Linke 《Journal of photochemistry and photobiology. A, Chemistry》1994,80(1-3):61-65
In this paper, we investigate the rotationally resolved spectra of hot CF radicals generated after IR multiphoton dissociation (IRMPD) of CFCl3 or CF2Cl2 and subsequent UV photodissociation. It is shown that these conditions are advantageous for the spectroscopy of transitions involving high rotational quantum numbers and hot bands. Thus molecular constants of CF for the first vibrationally excited state of the electronic ground state (Av=77.1 cm−1, Bv=1.389 cm−1, Dv=6.570×10−6 cm−1) are determined for the first time or are calculated more accurately. The spectroscopic method used was resonance-enhanced multiphoton ionization (REMPI) spectroscopy. 相似文献
999.
A sensitive and specific method for the determination of memantine in human plasma is presented. Memantine was extracted from plasma and derivatized to the pentafluorobenzoyl derivative in a one-step procedure avoiding any sample concentration steps. Amantadine was used as an internal standard. The compounds were measured by gas chromatography/negative ion chemical ionization mass spectrometry without any further processing. Using this detection mode, the fragment ions at m/z 353 and 325 were obtained at high relative abundance. Calibration graphs were linear over the range 0.117-30 ng ml(-1). At the limit of quantification (LOQ), the inter-assay precision was 2.00% and the intra-assay variability was 3.22%. The accuracy at the LOQ showed deviations of -1.42% (intra-assay) and -2.47% (inter-assay). The method is rugged, rapid and robust and was applied to the batch determination of memantine during pharmacokinetic profiling of the drug. 相似文献
1000.
Werner R. Thiel 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2003,115(44):5548-5550