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1.
In this article, we performed quantum chemical calculations to study the π Au-bond in the HCCH···AuX (X = OH, F, Cl, Br, CH(3), CCH, CN, and NC) system. For comparison, we also investigated the HCCH···Au(+) and H(2)CCH(2)···AuF complexes. The equilibrium geometries and infrared spectra at the MP2 level were reported. The interaction energies were calculated at the MP2 and coupled-cluster single double triple levels. The natural bond orbital results support the Dewar-Chatt-Duncanson model. Moreover, we focused on the influence of X atom on the geometries, interaction energies, and orbital interactions as well as the comparison between HCCH···AuF and H(2)CCH(2)···AuF complexes. Although the π Au-bond in these complexes is electrostatic in nature, the weight of covalent nature is also important. 相似文献
2.
We analyze the interplay between pnicogen‐bonding and halogen‐bonding interactions in the XCl? FH2P? NH3 (X=F, OH, CN, NC, and FCC) complex at the MP2/aug‐cc‐pVTZ level. Synergetic effects are observed when pnicogen and halogen bonds coexist in the same complex. These effects are studied in terms of geometric and energetic features of the complexes. Natural bond orbital theory and Bader’s theory of “atoms in molecules” are used to characterize the interactions and analyze their enhancement with varying electron density at critical points and orbital interactions. The physical nature of the interactions and the mechanism of the synergetic effects are studied using symmetry‐adapted perturbation theory. By taking advantage of all the aforementioned computational methods, the present study examines how both interactions mutually influence each other. 相似文献
3.
《Radiation Physics and Chemistry》2008,77(5):528-536
Taking into account the changes of the geometric shielding effect in a molecule as the incident electron energy varies, an empirical fraction, which depends on the energy of the incident electrons, the target's molecular dimension and the atomic and electronic numbers in the molecule, is presented. Using this empirical fraction, a new formulation of the additivity rule is proposed. Using the new additivity rule, the total cross sections of electron scattering by CO2, C2H2, CHCl3, CH2Cl2, CH3Cl, CHF3, CH2F2 and CH3F are calculated at the Hartree–Fork level at 30–5000 eV. The quantitative total cross sections are compared with those obtained by experiments and other theories, and good agreement is obtained over a wide energy range, especially above 100 eV. 相似文献
4.
Timothy R. Corkish Christian T. Haakansson Peter D. Watson Prof. Allan J. McKinley Dr. Duncan A. Wild 《Chemphyschem》2021,22(1):69-75
A combined experimental and theoretical approach has been used to investigate X−⋅⋅⋅CH2O (X=F, Cl, Br, I) complexes in the gas phase. Photoelectron spectroscopy, in tandem with time-of-flight mass spectrometry, has been used to determine electron binding energies for the Cl−⋅⋅⋅CH2O, Br−⋅⋅⋅CH2O, and I−⋅⋅⋅CH2O species. Additionally, high-level CCSD(T) calculations found a C2v minimum for these three anion complexes, with predicted electron detachment energies in excellent agreement with the experimental photoelectron spectra. F−⋅⋅⋅CH2O was also studied theoretically, with a Cs hydrogen-bonded complex found to be the global minimum. Calculations extended to neutral X⋅⋅⋅CH2O complexes, with the results of potential interest to atmospheric CH2O chemistry. 相似文献
5.
A new kind of single-electron lithium bonding complexes H(3)C...LiY (Y=H, F, OH, CN, NC, and CCH) was predicted and characterized in the present paper. Their geometries (C(3v)) with all real harmonic vibrational frequencies were obtained at the MP2/aug-cc-pVTZ level. For each H(3)C...LiY complex, single-electron Li bond is formed between the unpaired electron of CH(3) radical and positively charged Li atom of LiY molecule. Due to the formation of the single-electron Li bond, the C-H bonds of the CH(3) radical bend opposite to the LiY molecule and the Li-Y bond elongates. Abnormally, the three H(3)C...LiY (Y=CN, NC, and CCH) complexes exhibit blueshifted Li-Y stretching frequencies along with the elongated Li-Y bonds. Natural bond orbital analyses suggest ca. 0.02 electron transfer from the methyl radical (CH(3)) to the LiY moiety. In the single occupied molecular orbitals of the H(3)C...LiY complexes, it is also seen that the electron could of the CH(3) radical approaches the Li atom. The single-electron Li bond energies are 5.20-6.94 kcal/mol for the H(3)C...LiY complexes at the CCSD(T)aug-cc-pVDZ+BF (bond functions) level with counterpoise procedure. By comparisons with some related systems, it is concluded that the single-electron Li bonds are stronger than single-electron H bonds, and weaker than conventional Li bonds and pi-Li bonds. 相似文献
6.
用量子化学UMP2方法,在6-311++G**基组水平上研究了CH2X(X=H,F,Cl)与臭氧反应机理,全参数优化了反应过程中反应物、中间体、过渡态和产物的几何构型,在UQCISD(T)/6-311++G**水平上计算了它们的能量,并对它们进行了振动分析,以确定中间体和过渡态的真实性.从CH2X(X=H,F,Cl)与O3的反应机理的研究结果看,它们与O3反应的活性都比较强,相对而言,活性大小顺序为CH2F>CH3>CH2Cl,也就是说,CH2F自由基与臭氧间的反应活性最强,对大气臭氧的损耗将是最大的.同时研究还发现CH2X(X=H,F,Cl)系列自由基与O3的反应都是强放热反应. 相似文献
7.
《Chemical physics》1987,118(3):457-466
The gas-phase clustering reactions Cl− (ROH)n−1 + ROH ⇄ Cl− (ROH)n with n ⩽ 11 for ROH = H2O, CH3OH, C2H5OH, i-C3H7OH, n-C3H7OH, and t-C4H9OH were measured using a high-pressure mass spectrometer. It seems likely that for CH3OH and C2H5OH, six ligands complete the shell structure and that ligands with n ⩾ 7 belong to the outer shell. The bond energies D(ROH---Cl−) increase in the order H2O < CH3OH < C2H5OH < i-C3H7OH < t-C4H9OH < n-C3H7OH. The observed strong bond of n-C3H7OH---Cl− may be due to the fact that both the acidic hydrogen atoms in the −OH and terminal −CH3 of n-C3H7OH interact with Cl− with the most favorable configuration. For Cl− switching reactions, Cl− (H2O)n + (ROH)n ⇄ Cl− (ROH)n + (H2O)n, the ΔG0n values converge to the values of free energies of transfer of Cl− from water to ROH solvent ( = ΔG0n with n → ∞) with n ≈ 7. The observed convergence of ΔG0n is due to compensation of changes in enthalpy and entropy, i.e. both ΔH0n and TΔS0n show increasing divergence from the values of enthalpies and entropies of transfer of Cl− from water to ROH solvent, respectively, with n = 1 → 7. This is due to the stronger interactions of ROH with Cl− than that of H2O in the inner shell of Cl− (ROH)n at the expense of the less favorable entropy changes (less freedom of motion for ligands in the inner shell). 相似文献
8.
The reactions of Pt+ with CH3X (X=F, Cl) are studied experimentally by employing an inductively coupled plasma/selected‐ion flow tube tandem mass spectrometer and theoretically by density functional theory. Dehydrogenation and HX elimination are found to be the primary reaction channels in the remarkably different ratios of 95:5 and 60:40 in the fast reactions of Pt+ with CH3F and CH3Cl, respectively. The observed kinetics are consistent with quantum chemistry calculations, which indicate that both channels in the reaction with CH3F are exothermic with ground‐state Pt+(2D), but that HF elimination is prohibited kinetically because of a transition state that lies above the reactant entrance. The observed HF‐elimination channel is attributed to a slow reaction of CH3F with excited‐state Pt+(4F) for which calculations predict a small barrier. The calculations also show that both the HCl‐elimination and dehydrogenation channels observed with CH3Cl are thermodynamically and kinetically allowed, although the state‐specific product distributions could not be ascertained experimentally. Further CH3F addition is observed with the primary products to produce PtCH2+(CH3F)1,2 and PtCHF+(CH3F)1,2. With CH3Cl, sequential HCl elimination is observed with PtCH2+ to form PtCnH2n+ with n=2, 3, which then add CH3Cl sequentially to form PtC2H4+(CH3Cl)1–3 and PtC3H6+(CH3Cl)1,2. Also, sequential addition is observed for PtCHCl+ to form PtCHCl+(CH3Cl)1,2. 相似文献
9.
Del Bene JE Alkorta I Sanchez-Sanz G Elguero J 《The journal of physical chemistry. A》2011,115(46):13724-13731
Ab initio calculations have been carried out in a systematic investigation of P···N pnicogen complexes H(2)XP:NXH(2) for X ═ H, CH(3), NH(2), OH, F, and Cl, as well as selected complexes with different substituents X bonded to P and N. Binding energies for complexes H(2)XP:NXH(2) range from 8 to 27 kJ mol(-1) and increase to 39 kJ mol(-1) for H(2)FP:N(CH(3))H(2). Equilibrium structures have a nearly linear A-P-N arrangement, with A being the atom directly bonded to P. Binding energies correlate with intermolecular N-P distances as well as with bonding parameters obtained from AIM and SAPT analyses. Complexation increases (31)P chemical shieldings in complexes with binding energies greater than 19 kJ mol(-1). One-bond spin-spin coupling constants (1p)J(N-P) across the pnicogen interaction exhibit a quadratic dependence on the N-P distance for complexes H(2)XP:NXH(2), similar to the dependence of (2h)J(X-Y) on the X-Y distance for complexes with X-H···Y hydrogen bonds. However, when the mixed complexes H(2)XP:NX'H(2) are included, the curvature of the trendline changes and the good correlation between (1p)J(N-P) and the N-P distance is lost. 相似文献
10.
Al Mokhtar Lamsabhi Otilia Mó Manuel Yáñez Jean-Claude Guillemin 《Structural chemistry》2013,24(6):1789-1798
The structure and relative stability of the different conformers of RCH2CH2CN (R = CH3, F, Cl) cyanides and their corresponding isocyanides have been investigated through the use of high-level ab initio G4 theory as well as B3LYP/aug-cc-pVQZ and M06/aug-cc-pVQZ density functional theory calculations. This theoretical survey ratifies that the gauche conformer of butyronitrile is slightly more stable than the anti one, so that in the gas phase and at room temperature this compound should exist as a mixture of 57 % of the former and 43 % of the latter. Similar stability trends are predicted for the corresponding isocyanide isomer. Conversely, when the terminal methyl group of butyronitrile (or its isocyanide isomer) is replaced by F or Cl, the stability trends are reversed and the anti conformer becomes slightly more stable than the gauche one. These changes in relative stabilities could be traced through an analysis of the reduced density gradient which shows the existence of a stabilizing interaction between the terminal methyl group and the cyano (or isocyano) group in butyronitrile (or its isocyanide isomer), which becomes repulsive when this methyl group is replaced by F or Cl. 相似文献
11.
Hui Zhang Gui-ling Zhang Jing-yao Liu Cheng-yang Liu Bo Liu Ze-sheng Li 《Theoretical chemistry accounts》2009,122(1-2):107-114
Theoretical investigations are carried out on the title reactions by means of the direct dynamics method. The optimized geometries, frequencies and minimum energy path are obtained at the MP2/6-31 + G(d,p) level, and energetic information is further refined at the MC-QCISD (single-point) level. The rate constants for both reactions are calculated by the improved canonical variational transition state theory with the small-curvature tunneling correction in a wide temperature range 200–3,000 K. The theoretical rate constant is in good agreement with the available experimental data. Furthermore, the effects of different halogen substitution on the rate constants are also discussed. 相似文献
12.
1 INTRODUCTION The intermolecular interaction of bases in DNA or RNA is of immense interest and significance to che- mists and biologists alike. The interactions of these bases with metal cations, solvent molecules and other small molecules or ions would affect the struc- ture and biological properties or recognition process,which has been investigated widely[1~8]. Boron contained compounds are electron deficient com- pounds and have been extensively used as catalysts in chemical react… 相似文献
13.
Nathaniel L. Kitzmiller Mark E. Wolf Dr. Justin M. Turney Prof. Henry F. Schaefer III 《Chemphyschem》2021,22(1):112-126
Sulfur dioxide and hypohalous acids (HOX, X=F, Cl, Br, I) are ubiquitous molecules in the atmosphere that are central to important processes like seasonal ozone depletion, acid rain, and cloud nucleation. We present the first theoretical examination of the HOX⋯SO2 binary complexes and the associated trends due to halogen substitution. Reliable geometries were optimized at the CCSD(T)/aug-cc-pV(T+d)Z level of theory for HOF and HOCl complexes. The HOBr and HOI complexes were optimized at the CCSD(T)/aug-cc-pV(D+d)Z level of theory with the exception of the Br and I atoms which were modeled with an aug-cc-pwCVDZ-PP pseudopotential. 27 HOX⋯SO2 complexes were characterized and the focal point method was employed to produce CCSDT(Q)/CBS interaction energies. Natural Bond Orbital analysis and Symmetry Adapted Perturbation Theory were used to classify the nature of each principle interaction. The interaction energies of all HOX⋯SO2 complexes in this study ranged from 1.35 to 3.81 kcal mol−1. The single-interaction hydrogen bonded complexes spanned a range of 2.62 to 3.07 kcal mol−1, while the single-interaction halogen bonded complexes were far more sensitive to halogen substitution ranging from 1.35 to 3.06 kcal mol−1, indicating that the two types of interactions are extremely competitive for heavier halogens. Our results provide insight into the interactions between HOX and SO2 which may guide further research of related systems. 相似文献
14.
《Journal of organometallic chemistry》1986,315(2):187-199
The heats of reaction of HMo(CO)3C5H5 with CX4 (X = Cl, Br) producing XMo(CO)3C5H5 have been measured by solution calorimetry and are −31.8±0.9 and −34.4±2.0 kcal/mole, respectively. The heats of reaction of NaMo(CO)3C5H5 with I2 and CH3I producing IMo(CO)3C5H5 and H3CMo(CO)3C5H5 are −32.3± 1.3 and −7.7± 0.3 kcal/mole. Oxidation with Br2CCl4 yielding Br3Mo(CO)2C5H5 was measured for the following complexes: (C5H5(CO)3Mo)2, (−92.0±1.0 kcal/mole), BrMo(CO)3C5H5 (−24.9± 2.0 kcal/mole) and HMo(CO)3C5H5 (−60.7± 2.0 kcal/mole). These and other data are used to calculate the Mo–X bond strength for X = H, Cl, Br, I, and CH3. These bond strength estimates are compared to those reported for X2Mo(C5H5)2. Iodination of H3CMo(CO)3C5H5, reported in the literature to yield CH3I and IMo(CO)3C5H5, actually produces CH3C(O)I and I3Mo(CO)2C5H5. 相似文献
15.
Among the conglomeration of hydrogen bond donors, the C−H group is prevalent in chemistry and biology. In the present work, CHCl3 has been selected as the hydrogen bond donor and are X(CH3)2 are the hydrogen bond acceptors. Formation of C−H⋅⋅⋅X hydrogen bond under the matrix isolation condition is confirmed by the observation of red-shift in the C−H stretching frequency of CHCl3 and comparison with the simulated spectra. Stabilisation energy of all the three complexes is almost equal although the observed red-shift for the C−H⋅⋅⋅O complex is less compared to the C−H⋅⋅⋅S/Se complexes. The nature and origin of the hydrogen bond have been delineated using Natural Bond Orbital, Atoms in Molecules, Non-Covalent Interaction analyses, and Energy Decomposition Analysis. Charge transfer is found to be proportional to the observed red-shift. This work provides the first impression of C−H⋅⋅⋅Se hydrogen bond and its comparison with C−H⋅⋅⋅O/S hydrogen bond interaction under experimental condition. 相似文献
16.
The characteristics and structures of single-electron halogen bond complexes [H3C?Br-Y (Y = H, CCH, CN, NC, C2H3)] have been investigated by theoretical calculation methods. The geometries were optimized and frequencies calculated at the B3LYP/6-311++G** level. The interaction energies were corrected for basis set superposition error (BSSE) and the wavefunctions obtained by the natural bond orbital (NBO) and atom in molecule (AIM) analyses at the MP2/6-311++G** level. For each H3C?Br-Y complex, a single-electron Br bond is formed between the unpaired electron of the CH3 (electron donor) radical and the Br atom of Br-Y (electron acceptor); this kind of single-electron bromine bond also possesses the character of a “three-electron bond”. Due to the formation of the single-electron Br bond, the C-H bonds of the CH3 radical bend away from the Br-Y moiety and the Br-Y bond elongates, giving red-shifted single-electron Br bond complexes. The effects of substituents, hybridization of the carbon atom, and solvent on the properties of the complexes have been investigated. The strengths of single-electron hydrogen bonds, single-electron halogen bonds and single-electron lithium bonds have been compared. In addition, the single-electron halogen bond system is discussed in the light of the first three criteria for hydrogen bonding proposed by Popelier. 相似文献
17.
C70X2(X=H,F, Cl)的稳定性和电子光谱 总被引:1,自引:0,他引:1
用INDO方法研究C70H2四种异构体的稳定性, 表明其最稳定异构体为1, 9-C70H2和7, 8-C70H2, 两者能量差为16.3KJ.mol^-^1, 与实验值及ab initio计算值接近; 光谱计算表明, 其特征吸收峰与实验值一致。在此基础上预测C70F2和C70Cl2的稳定性和电子光谱, 表明C70F2四种异构体的稳定性顺序与C70H2一致, 而C70Cl2则以21, 42-异构体最为稳定。二者的电子光谱与C70H2极其相似只是在500nm以上有细微差别。 相似文献
18.
Parameter values of the non-blonded atom⋯atom interaction Br⋯OC have been established from gas-phase data. Conformational energies, structures, torsional barrier heights and torsional force constants of the title compounds have been estimated. For BrOCCH2Br, (Cl3C)2CO and (ClH2C)2CO the calculated results are compared with gas-phase observations. It is suggested that hexachloroacetone ought to be reinvestigated by electron diffraction. 相似文献
19.
Uzi Kaldor 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1994,31(4):279-282
The geometries of the Cl–NH3, Cl–H2O, F–NH3 and F–H2O clusters are optimized using the coupled cluster method. The four lowest ionization potentials are then calculated, leading to the ground and low excited states of the neutral species. The first three IPs describe ionization from the externalp state of the halogen atom, whereas the fourth corresponds to ionization from the NH3 or H2O moiety, leading to charge transfer complexes. These complexes were recently observed in the photoelectron spectrum of Cl–NH3, in full accord with our calculations.Supported in part by the U.S.-Israel Binational Science Foundation 相似文献
20.
Prof. Dr. Giulia de Petris Prof. Dr. Marzio Rosi Dr. Ornella Ursini Dr. Anna Troiani 《化学:亚洲杂志》2013,8(3):588-595
The H.‐atom transfer (HAT) reaction is investigated in the gas phase, starting from two different entrance channels, O2.+/CH2X2 and CH2X2.+/O2 (X=F, Cl), that correspond to a step of hydride transfer and to HAT, respectively. Analysis of the spin and charge along the reaction pathway shows that HAT occurs through the same reacting configuration, irrespective of whether the reactants are formed within the complex or are free isolated species. 相似文献