共查询到20条相似文献,搜索用时 15 毫秒
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The multiple-channel reactions SiH(3) + SiH(CH(3))(3) --> products are investigated by direct dynamics method. The minimum energy path (MEP) is calculated at the MP2/6-31+G(d,p) level, and energetic information is further refined by the MC-QCISD (single-point) method. The rate constants for individual reaction channels are calculated by the improved canonical variational transition state theory with small-curvature tunneling correction over the temperature range of 200-2400 K. The theoretical three-parameter expression k(T) = 2.44 x 10(-23)T(3.94) exp(-4309.55/T) cm(3)/(molecule s) is given. Our calculations indicate that hydrogen abstraction channel R1 from SiH group is the major channel because of the smaller barrier height among five channels considered. 相似文献
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Yang Yong Zhang Weijun Gao Xiaoming Pei Shixing Shao Jie Huang Wei Qu Jun Liu Anling 《化学物理学报(中文版)》2005,18(5):740-744
The reaction for SiH3+O(3P) was studied by ab initio method. The geometries of the reactants, intermediates, transition states and products were optimized at MP2/6-311+G(d,p) level. The single point calculations for all the stationary points were carried out at the QCISD(T) /6-311+G(d,p) level using the MP2/6-311+G(d,p) optimized geometries. The results of the theoretical study indicate that the major pathway is the SiH3+O(3P)→IM1→TS3→IM2→TS8→HOSi+H2. The other minor products include the HSiOH+H, H2SiO+H and HSiO+H2. Furthermore, the products HOSi, HSiO and HSiOH(cis) can undergo dissociation into the product SiO. In addition, the calculations provide a possible interpretation for disagreement about the mechanism of the reaction SiH4+O(3P). It suggests that the products HSiOH, H2SiO and SiO observed by Withnall and Andrews are produced from the secondary reaction SiH3+O(3P) and not from the reaction SiH4+O(3P). 相似文献
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M. G. Voronkov A. A. Korlyukov V. S. Fundamenskii É.A. Zels’bst M. Yu. Antipin 《Journal of Structural Chemistry》2010,51(3):534-539
Two polymorphic modifications of N-methylbis(2-hydroxyethyl)ammonium hexafluorosilicate (AHFS) crystallize in monoclinic symmetry. The independent part of the unit cell of the low temperature modification contains two cations and an anion. The cell volume is two times smaller in the high temperature modification, the [SiF6]2- anion being disordered. In both modifications of methylbis(2-hydroxyethyl)ammonium hexafluorosilicate (HOCH2CH2)2HN+[SiF6]2-, the [SiF6]2- anion and the (HOCH2CH2)2HN+CH3 cation are linked by F…H—O hydrogen bonds. The silicon atom polyhedron in the anion is a tetragonal bipyramid; the coordination polyhedron of the nitrogen atom in the cation is a tetrahedron. 相似文献
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Rate constants k1, k2, and k3 have been measured at 298 K by means of a laser photolysis-laser magnetic resonance technique and (or) by a laser photolysis-infrared chemiluminescence detection technique (LMR and IRCL, respectively). \hfill\hbox to 12em{$\rm Cl+I_2\longrightarrow ICl+I;$}\hbox to 8em{$\rm {\it k}_1=(2.5\pm 0.7)\times 10^{-10}(IRCL)$}\hfill(1)\\\hfill\hbox to 12em{}\hbox to 8em{$\rm {\it k}_1=(2.8\pm 0.8)\times 10^{-10}(LMR)$}\hfill \\\hfill\hbox to 12em{$\rm SiCl_3+I_2\longrightarrow SiCl_3I+I;$}\hbox to 8em{$\rm {\it k}_2=(5.8\pm 1.8)\times 10^{-10}(IRCL)$}\hfill (2)\\\hfill\hbox to 12em{$\rm SiH_3+I_2\longrightarrow SiIH_3+I;$}\hbox to 8em{$\rm {\it k}_3=(1.8\pm 0.46)\times 10^{-10}(LMR)$}\hfill (3)\\ As an average of the LMR and IRCL results we offer the value k1 = (2.7 ± 0.6) × 10−10. Units are cm3 molecule−1 s−1; uncertainties are 2σ including precision and estimated systematic errors. © 1997 John Wiley & Sons, Inc. Int J Chem Kinet 29: 25–33, 1997. 相似文献
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Hans Beat Bürgi Paloth Venugopalan Dieter Schwarzenbach Franois Diederich Carlo Thilgen 《Helvetica chimica acta》1993,76(5):2155-2159
The crystal structure of C70 · 6(S8) at 100 K shows C70 to be ordered and the S8 molecules to be partially disordered. The symmetry of C70 is D5h to within experimental accuracy. 相似文献
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Wei Jiang SI Shu Ping ZHUO * Guan Zhi JU School of Chemical Engineering Shandong University of Technology Zibo State Key Laboratory of coordination Chemistry Nanjing University Nanjing 《中国化学快报》2004,15(5)
Silicon chemistry has been attracted more attention because of its applications to the production of thin silicon films and the etching of silicon wafers in micro-electronics1. Silylidyne (SiH), which plays an important role in plasma chemical vapor deposition (CVD) processes, has been investigated in experimental research2-5. The reaction mechanism of SiH insertion reaction with small molecules such as XH3 (X=N, P) was recently studied by means of M豯ler-Plesset perturbation theory6.… 相似文献
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Hui Zhang Gui‐Ling Zhang Jing‐Yao Liu Miao Sun Bo Liu Ze‐Sheng Li 《Journal of computational chemistry》2010,31(2):403-411
The multiple‐channel reactions SiH3 + SiH3CH3 → products and SiH3 + SiH2(CH3)2 → products are investigated by direct dynamics method. The minimum energy path (MEP) is calculated at the MP2/6‐31+G(d,p) level, and energetic information is further refined by the MC‐QCISD method. The rate constants for individual reaction channels are calculated by the improved canonical variational transition state theory (ICVT) with small‐curvature tunneling (SCT) correction over the temperature range of 200–2400 K. The theoretical three‐parameter expression k1(T) = 2.39 × 10−23T4.01exp(−2768.72/T) and k2(T) = 9.67 × 10−27T4.92exp(−2165.15/T) (in unit of cm3 molecule−1 s−1) are given. Our calculations indicate that hydrogen abstraction channel from SiH group is the major channel because of the smaller barrier height among eight channels considered. © 2009 Wiley Periodicals, Inc. J Comput Chem 2010 相似文献