CH2X(X=H,F,Cl)与臭氧反应机理的量子化学研究

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.     

锗烯X_2Ge(X=H、CH_3、F、Cl、Br)与乙烯环加成反应的量子化学研究

利用量子化学密度泛函理论的B3LYP方法,在6-311G的水平上,对锗烯X2Ge(X=H、CH3、F、Cl、Br)与C2H4的环加成反应进行了计算研究.结果表明,锗烯的基态是单重态,取代基的电负性越强,单-三态的能量差越大;控制反应的因素是电子效应,而不是立体效应;取代基的电负性越强,反应的活化能越高,放热越少;该反应由两步组成,第一步生成中间配合物,是一个无势垒的放热过程,第二步经过渡态生成产物.     

锗烯X2Ge(X=H、CH3、F、Cl、Br)与乙烯环加成反应的量子化学研究

利用量子化学密度泛函理论的B3LYP方法,在6-311G**的水平上,对锗烯X2Ge(X=H、CH3、F、Cl、Br)与C2H4的环加成反应进行了计算研究.结果表明,锗烯的基态是单重态,取代基的电负性越强,单-三态的能量差越大;控制反应的因素是电子效应,而不是立体效应;取代基的电负性越强,反应的活化能越高,放热越少;该反应由两步组成,第一步生成中间配合物,是一个无势垒的放热过程,第二步经过渡态生成产物.     

NMR investigations on Stannabicycloundecanes of the type RSn(CH2CH2CH2)3N

The ¹H, ¹³C, and ¹¹⁹Sn NMR data of seven stannabicycloundecanes of the type RSn(CH₂CH₂CH₂)₃N (1, R = Cl; 2 , R = Br; 3 , R = I; 4 , R = OH; 5 , R = SPh; 6 , R = Me; 7 , R = Sn(CH₂CH₂CH₂)₃N) are reported. From ¹H NMR coalescence data at low temperature the free activation enthalpies for the racemisation of the bicyclo[3.3.3]skeleton were estimated to be 37 ± 1 kJ/mol. They are independent of the substituent R. However, it decreases when the tin atom is replaced by silicon for R = Me.     

Isomerizations of CH3SO2: Quantum Chemistry and Topological Study

The structures, stabilities and the isomerization reactions of CH₃SO₂ isomers in a doublet electronic state have been studied at B3LYP/6‐311+ +G (d,p), MP2/6‐311++G (d,p) and CCSD(T)/6‐311++G (d,p) levels. The three different levels of calculation give the similar results: thirteen minimum isomers were located and they were connected by eleven transition states. Among the thirteen isomers, cis‐CH₃OSO, trans‐CH₃OSO and CH₃SO₂ are the most stable species, and they should be detected easily in experiment. This is well consistent with the experimental result. These isomers could isomerize to each other by chemical bond vibration, chemical bond rotation and atom migration. The non‐planar ring structure transition state (STS), which was found in this paper, extended the concept of ring STS to the non‐planar systems.     

Au(II)化合物[Au(CH2)2PH2]2X2 (X＝F, Cl, Br, I)的量子化学理论研究

采用从头计算HF, MP2方法和密度泛函理论, 对Au(II)系列化合物[Au(CH₂)₂PH₂]₂X₂ (X＝F, Cl, Br, I)的几何结构、电子结构和振动频率进行了研究. 研究表明Au的5d和6s电子参与Au—Au以及Au—X之间的成键. Au—Au, Au—X键强烈的电子相关作用使HF方法不适于该体系的研究, BP86和B3LYP两种泛函给出较大的Au—Au和Au—X键长, 而MP2方法和局域的密度泛函方法则给出了合理的结构参数. 局域密度泛函方法计算得到的Au—Au键和 Au—X键振动频率也与实验数据符合较好. 还运用含时密度泛函理论计算了[Au(CH₂)₂PH₂]₂X₂的电子激发能, 对分子在紫外-可见光谱范围内的电子跃迁进行了分析, 考察了卤素配体对激发能的影响, 并结合分子轨道能级的变化对此给予了解释.     

Conformational studies by dynamic NMR. 91. Conformational stereodynamics of tetraethylmethane and analogous C(CH2X)4 compounds

Variable-temperature NMR studies of tetraethylmethane (1a), tetrapropylmethane (1b), tetrachloromethylmethane (1c), tetrabromomethylmethane (1d), tetracyclopropylmethylmethane (1e), and tetrabenzylmethane (1f) show a range of dynamic behavior. Separate signals for two types of conformation are observed for 1a, 1c, and 1d at low temperatures, with more than 95% of the molecules in a time-averaged D2d conformation, and the S4 conformation as the minor populated alternative. Compound 1e populates only S4-type conformations but equilibrates slowly between degenerate versions of these at low temperatures. Compounds 1b and 1f show a temperature-dependent spectrum but the low-temperature limit spectrum could not be observed. Ab initio calculations agree well with experiment on the conformational equilibria and suggest in particular that compounds 1b and 1f behave similarly to compounds 1a and 1e, respectively. A crystal structure of compound 1f is reported.     

Decomposition of P2S2N4(Si(CH3)3)4A12C14 as Studied by FT-Raman and Quantum Chemistry Means

The dimeric title compound decomposes upon heating to give the monomer and desulphurized monomer as shown by FT-Raman and quantum chemical means.     

The relationship between transannular secondary bonding strength and conformation in diphenyldithiophosphinate stibocanes X(CH2CH2S)2SbS2PPh2 (X = O,S)

The two stibocanes 1-oxa-4,6-dithia-5-stibocane diphenyldithiophosphinate O(CH₂CH₂S)₂SbS₂PPh₂ 1 and 1,3,6-trithia-2-stibocane diphenyldithiophosphinate S(CH₂CH₂S)₂ · SbS₂PPh₂ 2 were prepared from the corresponding chloro oxa- and thia-stibocanes 3 and 6 , and the ammonium salt of diphenyldithiophosphinic acid in CH₂Cl₂. 1 and 2 were characterized by IR, EI-MS and multinuclear NMR (¹H, ¹³C, ³¹P{¹H}). The crystalline state of 1 features two Sb1 ? S1 intermolecular interactions [3.987(2) Å] that results in a dimer. Alongside 1 displays both an endocyclic, transannular Sb1 ? O1 interaction [2.555(6) Å] and an exocyclic Sb1 ? S4 secondary interaction [3.327(2) Å]. The coordination geometry at the antimony could be described as AX₄YE ψ-trigonal bipyramid geometry with A = Sb, X = S1, S2, S3,O1; Y = S4; S1, S2 and the lone pair lays on the equatorial plane with O1 and S4 in axial positions. The Sb1 ? S4 secondary bonding is face capping one of the planes form by the lone pair, S2 and S3 of the trigonal bipyramid. 2 also displays both an endocyclic, transannular Sb1 ? S2 interaction [2.949(3) Å] and an exocyclic Sb1 ? S5 secondary interaction [3.216(3) Å]. The antimony becomes five-coordinate, giving the AX₄YE ψ-trigonal bipyramid geometry with S1, S3 and the lone pair laying on the equatorial plane with S2 and S4 in axial positions. The Sb1 ? S5 also here is face capping the plane form by the lone pair, S3 and S4 of the trigonal bipyramid. The conformation of the eight membered ring in 2 is boat-chair. In 1 the main conformation is chair-planar. Die Konformation des Achtringes in 2 ist Wanne-Sessel. In 1 ist die Konformation des Achtringes Sessel-planar.     

Reaction mechanism of HSH and CH3SH with NH2CH2COCH2X (X = F and Cl) molecules

The reaction mechanism of model compounds H₂S and CH₃SH for cysteine proteases with NH₂CH₂COCH₂X (X = F and Cl) molecules has been investigated using DFT methods with B3LYP and B3PW91 hybrid density functionals at 6‐31+G* basis sets. The single point energy has been calculated for the above reactions with B3LYP and B3PW91 functionals using aug‐cc‐PVDZ infinite basis set in both gas and solution phases. The intrinsic reaction coordinates calculations have been performed to confirm that each transition state is linked by the desired reactants and products. The geometries and relative energies for various stationary points have been determined and discussed. The zero point vibrational energy corrections have been made to predict the reliable energy. The negative value of reaction energy indicates that the overall reaction profile is found to be exothermic. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2008     

CH2NH与O(3P)反应的量子化学及电子密度拓扑研究

采用B3LYP、MP2(full)和 QCISD 三种方法在6-311G(d, p)和aug-cc-pVDZ基组水平上对三线态O(3P)原子与CH2NH(s)的反应进行了详细的理论研究. 采用B3LYP和MP2(full)方法对反应势能面上的各驻点进行了几何构型优化, 通过振动频率分析证实了过渡态的真实性, 内禀反应坐标(IRC)跟踪验证了过渡态与反应物和产物的连接关系, 用上述三种方法计算得到了各反应通道的反应势垒. 对反应过程中的一些重要点进行了电子密度拓扑分析研究. 研究结果表明, O(3P)原子进攻CH2NH(s)中的N2原子和C1原子生成CH2NHO(t)和OCH2NH(t), CH2NHO(t)中N2上的H5可迁移到C1上异构化为CH3NO(t).     

CH_2X(X=H,FCI)与臭氧反应机理的最子化学研究

用量化学UMP2方法，在6-311++G**基组水平上研究了CH_2X(X=H,FCI)与臭氧反 应机理，全参数优化了反应过程中反应物、中间体、过渡态和产物的内何构型，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直实性。从CH_2X(X=H,FCI)与O_3的反应机理的研究结果看 ，它们与O_3反应的活性都比较强，相对而言，活性大小顺序为CH_2F＞CH_3＞ CH_2CI，也就是说，CH_2F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CH_2X(X=H,FCI)系列自由基与O_3的反应都是强放热反 应。     

Analysis of vibrational spectra of 3-halo-1-propanols CH(2)XCH(2)CH(2)OH (X is Cl and Br)

The conformational stability and the three rotor internal rotations in 3-chloro- and 3-bromo-1-propanols were investigated by DFT-B3LYP/6-311+G and ab initio MP2/6-311+G, MP3/6-311+G and MP4(SDTQ)//MP3/6-311+G levels of theory. On the calculated potential energy surface twelve distinct minima were located all of which were not predicted to have imaginary frequencies at the B3LYP level of theory. The calculated lowest energy minimum in the potential curves of both molecules was predicted to correspond to the Gauche-gauche-trans (Ggt) conformer in excellent agreement with earlier microwave and electron diffraction results. The equilibrium constants for the conformational interconversion of the two 3-halo-1-propanols were calculated at the B3LYP/6-311+G level of calculation and found to correspond to an equilibrium mixture of about 32% Ggt, 18% Ggg1, 13% Tgt, 8% Tgg and 8% Gtt conformations for 3-chloro-1-propanol and 34% Ggt, 15% Tgt, 13% Ggg1, 9% Tgg and 7% Gtt conformations for 3-bromo-1-propanol at 298.15K. The nature of the high energy conformations was verified by carrying out solvent experiments using formamide ( epsilon=109.5) and MP3 and MP4//MP3 calculations. The vibrational frequencies of each molecule in its three most stable forms were computed at the B3LYP level and complete vibrational assignments were made based on normal coordinate calculations and comparison with experimental data of the molecules.     

聚并苯和取代聚并苯电子性质的量子化学研究

准一维聚并苯体系是一类典型的梯形结构有机导体材料．采用量子化学一维紧束缚自洽场晶体轨道ＣＮＤＯ／２　方法，研究了顺、反式聚并苯和取代聚并苯的结构、能量和电子布居．计算了甲基、甲氧基、氯和羟基取代聚并苯的电子能带，与聚并苯进行了分析比较．结果表明：（１）单取代使对称性明显降低，对聚并苯的能带结构影响较大，使能隙值普遍增大，导电性能降低．（２）双取代虽使电荷重新分布，但基本保持聚并苯自身结构特征．取代聚并苯与聚并苯比较能隙值变化不大．对于不同的取代基影响规律不同．对位双取代与间位双取代也表现出差异．（３）顺式和反式结构聚并苯的电子性质略有差异，取代后变化较大．     

Syntheses and Crystal Structures of [Na（H2O）1/2]X and NH2（CH2CH3）2X and Antioxidant Activity of the Former

In order to enhance the water-solubility and biological utilization rate of chrysin, sodium 5,7-dihydroxylflavone-8-sulfonate （1, [Na（H2O）1/2]X, X = C15H9OSO3, 5,7-dihydroxylfla- vone-8-sulfonate） was synthesized and its structure was identified on the basis of NMR, FT-IR and elemental analysis. The assembly of 5,7-dihydroxylflavone-8-sulfonate with diethylamide cation afforded diethylamide 5,7-dihydroxylflavone-8-sulfonate （2, NH2（CH2CH3）2X） which was characterized by FT-IR and elemental analysis. The crystal structures of 1 and 2 were determined by X-ray single-crystal diffraction analysis. The crystal of 1 is of triclinic system, space group P1, with a = 8.5628（13）, b = 12.8916（19）, c = 13.562（2） A, α = 82.494（1）, β = 78.601（2）, γ = 84.033（2）°, C30H20Na2O15S2, Z = 2, Mr = 730.59, V = 1450.3（4） A3, Dc = 1.673 g/cm3, F（000） = 748, p = 0.295 mm^-1, the final R = 0.0641 and wR = 0.1458. The crystal of 2 crystallizes in the triclinic system, space group Pi, with a = 7.689（2）, b = 11.184（3）, c = 11.734（3） A, α = 74.268（3）, βl = 81.751（4）, γ= 87.991（3）°, C19H21NO7S, Z = 2, Mr= 407.43, V= 961.2（4） A3, Dc = 1.408 g/cm3, F（000） = 428, p = 0.210 mm^-1, the final R = 0.0484 and wR = 0.1195. In 1, the three-dimensional structure is organized into organic and inorganic regions; the flavone skeletons are stacked into organic regions by π...π staeking interactions; inorganic regions are generated by Na-O coordination bonds among sulfonate groups, coordinated water molecules and NaI. The sulfonate groups play an important role as a bridge of inorganic and organic regions. One-dimensional chain structure of 2 is extended by N-H…O hydrogen bonds and π...π stacking interactions. Furthermore, the antioxidant activity of 1 was evaluated. The scavenging activity of 1 to DPPH free radical is better than that of the parent compound chrysin.     

Reactions of S4N4 with diphosphines,Ph2P(X)PPh2 (X = NC4H8N,CH2CH2)

Reactions of S₄N₄ with diphosphines, Ph₂P(X)PPh₂ (X = NC₄H₈N, CH₂CH₂) have resulted in the isolation of N₃S₃? NPPh₂(X)Ph₂PN? S₃N₃ (X = NC₄H₈N, CH₂CH₂), (S)PPh₂(CH₂CH₂)Ph₂PN? S₃N₃, and (S)PPh₂NC₄H₈NPh₂P(S) as new compounds. These heterocycles have been characterized by analytical and spectroscopic (IR, UV-VIS, ¹H and ³¹P-NMR, and MS) techniques.     

The Jahn-Teller effect in CH(3)CN(+) (X(2)E) and CD(3)CN(+) (X(2)E) studied by zero kinetic energy photoelectron spectroscopy

The Jahn-Teller effect in CH(3)CN(+) (X(2)E) and CD(3)CN(+) (X(2)E) has been found experimentally by zero kinetic energy (ZEKE) photoelectron spectroscopy using coherent extreme ultraviolet (XUV) radiation. The vibronic bands of CH(3)CN(+) (X(2)E) and CD(3)CN(+) (X(2)E) at about 4500 cm(-1) above the ground states have been recorded. The spectra consist mainly of the Jahn-Teller active C-C[triple bond]N bending (v(8)), the CN stretching (v(2)), the CH(3) (CD(3)) deforming (v(6)), and the C-C stretching (v(4)) vibronic excitations. The Jahn-Teller active vibronic bands (v(8)) have been assigned with a harmonic model including linear and quadratic Jahn-Teller coupling terms, taking into account only the single mode vibronic excitation. The ionization potentials of CH(3)CN and CD(3)CN have also been determined, and their values are 12.2040(+/-0.001) and 12.2286(+/-0.001) eV, respectively.     

RN (R＝CH3, CH3CH2)异构化及脱氢反应的量子拓扑研究

利用量子化学从头算CASSCF方法在6-311＋G (d, p)基组水平上对单线态和三线态RN (R＝CH₃, CH₃CH₂)异构化反应及RN脱氢反应的微观机理进行了理论研究. 在MP2/6-311＋G (d, p)和CCSD/6-311＋G (d, p)水平上进行了单点能校正. 单态和三态势能面的交叉点(ISC)的存在清楚地说明了基态反应物³RN异构化为基态产物¹R'NH (R'＝CH₂, CH₃CH)的过程. 电子密度拓扑分析显示在整个异构化过程中有两种类型的结构过渡态: 单态反应通道为T型过渡态, 三态反应通道为环状过渡态. 单线态RN脱氢反应通道中“原子-分子键”的存在说明两个H原子是以H₂的形式从RN中脱去的.