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Von R. Demuth 《无机化学与普通化学杂志》1976,427(3):221-228
Inhaltsübersicht. Verschiedene Methoden zur Darstellung von F3SiAs(CH3)2 und F3SiP(CH3)2 werden mitgeteilt und diskutiert. Die neuen Trifluorsilylverbindungen werden durch KMR- und IR-Spektren sowie durch Umsetzung mit polaren Reaktanden charakterisiert, Die Schwingungsspektren des F3SiAs(CH3)2 werden mit Hilfe einer Normalkoordinatenanalyse näher untersucht. Preparation and Vibrational Spectra of F3SiAs (CH3)2 and F3SiP(CH3)2 Various preparative routes for the synthesis of F3SiAs(CH3)2 and F3SiP(CH3)2 are discussed. The new trifluoro-silyl compounds are characterized by n.m.r. and i.r. spectra as well as by the reaction with polar compounds. The vibrational spectra of F3SiAs(CH3)2 are investigated using a normal coordinate analysis. 相似文献
3.
Enrique M. Cabaleiro-Lago Jes��s Rodr��guez-Otero ��ngeles Pe?a-Gallego 《Theoretical chemistry accounts》2011,128(4-6):531-539
A computational study of dimers formed by aniline and one or two CH3X molecules, X being CN, Cl or F, was carried out to elucidate the main characteristics of the interacting systems. Two different structures were found for each of the dimers, depending on the relative location of the CH3X molecule with respect to the NH2 hydrogen atoms. The most stable complex is formed with acetonitrile, with a complexation energy amounting to ?27.0?kJ/mol. Methyl chloride and methyl fluoride form complexes with complexation energies amounting to ?18.1 and ?17.5?kJ/mol, respectively, though the structural arrangement is quite different for both structures. In most complexes, the leading contribution to the stabilization of the complex is dispersion, though the electrostatic contribution is almost as important. Three different minima were obtained for clusters containing two CH3X molecules depending on the side they occupy with respect to the phenyl ring. The complexation energies for these structures amount to ?58.5, ?38.6 and ?36.3?kJ/mol for acetonitrile, methyl chloride and methyl fluoride, respectively. 相似文献
4.
Pawel Rodziewicz Konstanty S Rutkowski Sonia M Melikova Aleksander Koll Francesco Buda 《Chemphyschem》2006,7(6):1221-1228
Fluoroform, as confirmed by both experimental and theoretical studies, can participate in improper H-bond formation, which is characterized by a noticeable increase in the fundamental stretching frequency nu(C-H) (so-called blue frequency shift), an irregular change of its integral intensity, and a C-H bond contraction. A Car-Parrinello molecular dynamics simulation was performed for a complex formed by fluoroform (F3CH) and deuterated methyl fluoride (FCD3) in liquid nitrogen. Vibrational analysis based on the Fourier transform of the dipole moment autocorrelation function reproduces the blue shift of the fundamental stretching frequency nu(C-H) and the decrease in the integral intensity. The dynamic contraction of the C-H bond is also predicted. The stoichiometry of the solvated, blue-shifted complexes and their residence times are examined. 相似文献
5.
Wang Y Liu JY Yang L Zhao XL Ji YM Li ZS 《The journal of physical chemistry. A》2007,111(32):7761-7770
The hydrogen abstraction reactions of CH3CHFCH3 and CH3CH2CH2F with the OH radicals have been studied theoretically by a dual-level direct dynamics method. The geometries and frequencies of all the stationary points are optimized by means of the DFT calculation. There are complexes at the reactant side or exit route, indicating these reactions may proceed via indirect mechanisms. To improve the reaction enthalpy and potential barrier of each reaction channel, the single point energy calculation is performed by the MC-QCISD/3 method. The rate constants are evaluated by canonical variational transition state theory (CVT) with the small-curvature tunneling correction method (SCT) over a wide temperature range 200-2000 K. The canculated CVT/SCT rate constants are consistent with available experimental data. The results show that both the variation effect and the SCT contribution play an important role in the calculation of the rate constants. For reactions CH3CHFCH3 and CH3CH2CH2F with OH radicals, the channels of H-abstraction from -CHF- and -CH2- groups are the major reaction channels, respectively, at lower temperature. Furthermore, to further reveal the thermodynamics properties, the enthalpies of formation of reactants CH3CHFCH3, CH3CH2CH2F, and the product radicals CH3CFCH3, CH3CHFCH2, CH3CH2CHF, CH3CHCH2F, and CH2CH2CH2F are studied using isodesmic reactions. 相似文献
6.
Ottaviani P Caminati W Favero LB Blanco S López JC Alonso JL 《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(3):915-920
The molecular beam Fourier transform microwave spectrum of cyclobutanone-trifluoromethane has been assigned and measured. The carbon atom of trifluoromethane lies in the plane of the heavy atoms of cyclobutanone. The complex is stabilized by one C-H...O=C and two C-H...F-C weak hydrogen bonds. The C-H...O=C interaction, involving one carbonylic oxygen, is studied for the first time in detail with rotationally resolved spectroscopy. The two C-H...F-C weak hydrogen bonds involve two fluorine atoms of trifluoromethane and two hydrogens of the same methylenic group in the alpha position. 相似文献
7.
By using molecular beam apparatus the visible (450–900 nm) chemiluminescence of the reaction F + CH3F was investigated. Seven vibronic bands of HCF (Ã1A-XA') and four vibrational bands of HF ground state overtone transitions were obtained. The relative vibrational state distributions of HF (V'=4,5,6) states and the rotational temperature of HF (V'=3) state were obtained. The analyses show that the two kinds of spectra were caused by the secondary reaction F+CH3F. The results may be helpful to explain the contradictory results of the experiments in F+CH3F system. 相似文献
8.
O. Keller C. Mang M. Nikola G. Schulz 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1996,37(4):315-322
Emission spectra following electron impact on CH3F, CH2F2 and CHF3 at various energies have been investigated in the spectral region from 200 nm to 700 nm. Emission thresholds and excitation functions for atomic and molecular fragments have been determined. Absolute emission cross sections were obtained for two band systems, A 2 Δ → X 2 Π, C 2 Σ+ → X 2 Π, observed in the emission spectrum of CH3F and for the H-Balmer radiation, H α ? H γ, in the spectra of all compounds. The continuous emission between 200 nm and 400 nm in the spectra of CH2F2 and CHF3 has been examined systematically. It was found that CF2(Ã) is the main precursor in both spectra. 相似文献
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《Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy》1976,32(1):175-183
The i.r. spectra of gaseous and solid CH3CCl2F and CH3CHClF have been recorded from 140 to 4000 cm−1. The corresponding Raman spectra of the liquids have also been recorded and depolarization values have been measured for the CH3CCl2F molecule. Also the Raman spectrum of gaseous CH3CHClF has been recorded. All spectra have been interpreted in detail and the 18 normal vibrations of both molecules have been characterized. Hot bands of the internal torsional mode for CH3CCl2F were observed at 248(2 ← 1) and 232 cm−1 (3 ← 2) in the far-i.r. spectrum of the gas. These frequencies are in good agreement with those calculated using the 4·42 kcal/mole barrier obtained in an earlier Raman study. The internal torsional mode for CH3CHClF was observed at 261 cm−1 in the spectra of the solid and the three-fold periodic barrier was calculated to be 4·38 kcal/mole. The barriers are compared in a series of chloro, fluoro and bromo substituted ethane derivatives. 相似文献
11.
在B3LYP/6-31+G(d,p)理论水平下采用基于波恩-奥本海默近似的从头算分子动力学方法重新研究了O-与CH3F反应经抽氢生成OH-和生成H2O的两条产物通道.反应轨线从反应初始过渡态开始,采用300K时的热取样确定初始条件,同时为对比不同的初始碰撞平动能条件下产物通道的变化,分别限定过渡矢量上的能量为2.1、36.8及62.8kJ·mol-1进行轨线计算,所有轨线计算的结果表明抽氢生成OH-的过程始终为主要的产物通道.我们的计算不仅进一步证实了以往实验的结论,而且描绘了抽氢生成OH-和生成H2O这两个产物通道在反应出口势能面上的动态反应路径,更为深刻地揭示了该反应的微观机理. 相似文献
12.
Jens Sehested Lene K. Christensen Ole J. Nielsen Timothy J. Wallington 《国际化学动力学杂志》1998,30(12):913-921
Using a pulse-radiolysis transient UV–VIS absorption system, rate constants for the reactions of F atoms with CH3CHO (1) and CH3CO radicals with O2 (2) and NO (3) at 295 K and 1000 mbar total pressure of SF6 was determined to be k1=(1.4±0.2)×10−10, k2=(4.4±0.7)×10−12, and k3=(2.4±0.7)×10−11 cm3 molecule−1 s−1. By monitoring the formation of CH3C(O)O2 radicals (λ>250nm) and NO2 (λ=400.5nm) following radiolysis of SF6/CH3CHO/O2 and SF6/CH3CHO/O2/NO mixtures, respectively, it was deduced that reaction of F atoms with CH3CHO gives (65±9)% CH3CO and (35±9)% HC(O)CH2 radicals. Finally, the data obtained here suggest that decomposition of HC(O)CH2O radicals via C C bond scission occurs at a rate of <4.7×105 s−1. © 1998 John Wiley & Sons, Inc. Int J Chem Kinet 30: 913–921, 1998 相似文献
13.
近年来, 我们在研究含氟烯烃和烷烃的红外激光诱导氧化和氯化反应的基础上, 深入研究了红外激光诱导卤代烷烃的脱卤化氢并生成: CF2卡宾和:CFCF3卡宾的反应[1-4]以往的研究往往是根据反应产物推论反应机理, 认为在反应过程中存在着卡宾中间体,但在实验中未能直接检测到. Kakimoto[5,6]曾报道过在流动体系中测到了.F+CH3F和.F+CH3Cl反应中:CHF和:CHCl的激光荧光激发谱, 但没有讨论卡宾形成的机理.Hirota[7]在讨论.F+CH3F反应时, 认为:CHF可能由攫氢过程产生而对于.F+CH3Cl反应同时生成:CHF和:CHCl未做说明. 本实验中用扩散分子束代替了流动反应体系, 从而大大减少了产物和反应物气体分子间的猝灭过程, 获得了信噪比大而清晰的图谱, 由此确证了:CHF和:CHCl的存在, 说明了.F+CH3Cl反应中自由基攫氢过程和偶合反应过程共存的反应历程. 这一结论对红外激光诱导一碳卤代宾化学反应机理研究有重要参考意义. 相似文献
14.
《Chemical physics》1987,113(2):251-263
Fluoromethane (CH3F) has been studied by binary (e,2e) coincidence spectroscopy at 1200 eV using non-coplanar symmetric kinematics. Separation energy spectra have been determined in the energy range up to 50 eV at azimuthal angles of 0° and 9°. The separation energy spectra and electron momentum distributions measured for the valence orbitals of CH3F and CH3Cl are compared with the results of calculations employing SCF wavefunctions and outer valence as well as extended 2ph—TDA Green function methods. Electron density and momentum density maps have been generated for all valence orbitals of both molecules using the SCF wavefunctions and are used to explain differences in the bonding properties of the halomethanes investigated here. 相似文献
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The title reaction was studied in a crossed‐beam experiment, in which the ground‐state methyl products were probed using a time‐sliced velocity‐imaging technique. By taking images over the energy range of chemical significance, from the threshold to about 15 kcal mol?1, the reactive excitation function as well as the dependences of product angular distributions and of the energy disposal on initial collision energies were determined. All experimental data are consistent with the picture that the ground‐state reaction of O(3P)+CH4 proceeds via a direct abstraction rebound‐type mechanism with a narrow cone of acceptance. Deeper insights into the underlying mechanism and the key feature of the potential‐energy surface are elucidated by comparing the results with the corresponding observables in the analogous Cl+CH4 reaction. 相似文献
16.
Laser-ablated Ti atoms react with CH(3)F upon condensation with excess argon to form primarily CH(3)TiF and (CH(3))(2)TiF(2). Irradiation in the UV region promotes alpha-hydrogen rearrangement of CH(3)TiF to CH(2)=TiHF and increases the yield of (CH(3))(2)TiF(2). Annealing to allow diffusion and reaction of more CH(3)F markedly increases the yield of (CH(3))(2)TiF(2). This shows that the CH(3)TiF + CH(3)F reaction is spontaneous and that triplet state CH(3)TiF is an extremely reactive molecule. B3LYP calculations are extremely effective in predicting vibrational frequencies and isotopic shifts for CH(3)TiF and (CH(3))(2)TiF(2) and thus in confirming their identification from matrix infrared spectroscopy. 相似文献
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Urata S Tsuzuki S Takada A Mikami M Uchimaru T Sekiya A 《Journal of computational chemistry》2004,25(3):447-459
The intermolecular interaction energy curves of CH(3)OCH(3)-CH(2)F(2), CF(3)OCH(3)-CH(2)F(2), CF(3)OCF(3)-CH(2)F(2), CH(3)OCH(3)-CHF(3), CF(3)OCH(3)-CHF(3), and CF(3)OCF(3)-CHF(3) complexes were calculated by the MP2 level ab initio molecular orbital method using the 6-311G** basis set augmented with diffuse polarization functions. We investigate the fluorine substitution effects of both methane and dimethyl ether on intermolecular interactions. In addition, orientation dependence of intermolecular interaction energies is also studied with utilizing eight types of orientations. Our analyses demonstrate that partial fluorinations of methane make electrostatic interaction dominant, and consequently enhance attractive interaction at several specific orientations. On the contrary, fluorine substitutions of dimethyl ether substantially decrease the electrostatic interaction between ether and CH(2)F(2) or CHF(3); thus, there is no such characteristic interaction between the C-H of fluorinated methane and ether oxygen of CF(3)OCF(3) as conventional hydrogen bonding, due to reduced polarity of fluorinated ether. The combination of different pairs of the electrostatic interaction is therefore responsible for the intermolecular interaction differences among the complexes investigated herein and also their orientations. 相似文献
18.
F. G. Celii K. C. Janda 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1988,10(2-3):347-360
We report infrared photodissociation spectra for Ne, Ar, Kr, N2 and CH4 clusters which contain CH3F chromophores. The CH3Fv 3 mode is excited with a line tunable CO2 laser. Mass spectrometer detection of changes in the cluster beam intensity serve to partially distinguish the spectra of different size neutral clusters. Many spectra consist of rather broad, inhomogeneous profiles. For intermediate size ArnCH3F clusters a sharp, narrow peak is observed in the spectrum. We assign this peak as due to a cluster in which a central CH3F molecule is surrounded by at least a full shell of Ar atoms packed in a contracted icosohedral geometry. Because the Ar atoms in a gas phase cluster are unconstrained by an extended crystalline structure, the CH3F dipole is more fully stabilized (and thus red-shifted) than in a solid matrix. The dependence of the observed spectrum on cluster size is discussed. For comparison, no comparable narrow spectral features are observed in ArnC2H4 cluster spectra. Clear evidence is also presented that the fragmentation of the neutral clusters upon electron impact ionization is fairly specific. Finally, we note that ionization of ArnCH3F clusters sometimes produces ArnF+ ions. This is a fragmentation process which does not occur in free CH3F. 相似文献
19.
Charles E. Hudson David J. McAdoo 《Journal of the American Society for Mass Spectrometry》1998,9(2):130-137
Ab initio calculations establish that CH3O+=CHCH3 (1) rearranges in gas phase isolation to CH2=O+C2H5 (2) directly rather than through CH3OCH2CH 2 + (3). The reaction is predicted to be antarafacial, in accord with the Woodward-Hoffmann (W-H) predictions. We predict an activation energy of 212.0 kJ/mol for this process at the QCISD(T)/6-311G**//MP2/6-311G** level. We also reinvestigated the degenerate rearrangement of CH3O=CH 2 + by a 1,3-sigmatropic shift. The W-H model is not a good one for the transition state (TS) for the latter reaction because the π bonding has been completely broken off. That TS is stabilized by three-center bonding between the carbons and the hydrogen being transferred. We also examined the questions of the importance of polarization functions on hydrogen and a set of outer valence functions on all the atoms in describing these hydrogen transfer TSs, and whether it is necessary to include these functions in the TS optimization runs. For the rearrangements we studied, polarization functions on hydrogen are crucial only for 1,2 hydrogen shifts. The 6-31G* basis set is adequate and good for the optimization of TSs of other ring sizes. For the 1,3 and 1,4 shifts we examined, a combination of both outer valence functions and polarization functions on hydrogen causes reductions in the computed activation energies ranging from 5.9 kJ/mol for the 1,4 shift at the RHF level to 15.6 kJ/mol for the 1,3 shift at the MP2 level. 相似文献
20.
The structure, harmonic frequencies, and binding energy of the trimethylgallium-arsine adduct, (CH3)3Ga: AsH3, have been computed using ab initio molecular orbital methods, and, where possible, compared with experimental results. The structures and frequencies of the precursors trimethylgallium and arsine are perturbed to only a small extent upon adduct formation. The binding energy of (CH3)3Ga: AsH3 is found to be 5.2 kcal/mol lower than that for H3Ga:AsH3 at the MP2/HUZSP*//RHF/HUZSP* level of computation. 相似文献