CH2 CHF与臭氧反应机理的量子化学研究

用量子化学MP2方法,在6-311+ +G(d,p)基组水平上研究了烯烃CH2CHF与臭氧反应的机理,对氟代乙烯臭氧化反应Criegee机理进行了系统的计算,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QCISD(T)/6-311+ +G(d,p)水平上计算了它们的能量.并对它们进行了频率分析,以确定中间体和过渡态的真实性.研究结果表明,氟代乙烯与臭氧反应沿Criegee机理是可信的、合理的.同时研究还发现,就氟代乙烯与臭氧反应活性而言,其控制步骤的位垒较低,可以说氟代乙烯与臭氧反应活性较强,也就是说氟代乙烯对臭氧的损耗较大.     

CH3(2A′)自由基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CH3(2A′)自由基与臭氧反应机理，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；同时应用经典过渡态理论计算了反应的速率常数，并与实验值进行了比较, CH3自由基与臭氧反应速率常数的理论计算结果为: 4.73×10－14 cm3•molecule－1•s－1，与实验报导的结果(k=2.52×10－14 cm3•molecule－1•s－1)很接近，同时发现CH3(2A′)自由基与O3的反应是强放热反应.     

CH2与HNCO反应机理的量子化学研究

异氰酸(HNCO)分解引发的一系列自由基反应是氮氧化物快速消除机理所研究的领域,由于该反应在燃烧化学中讨论氮氧化物NOx的消除过程十分重要,所以获得这些反应准确的位垒就成为实验化学和理论化学所要解决的问题,本文采用量子化学方法,研究了CH2与HNCO体系的反应机理,力求从理论角度给出合理的解释。     

OXO(X=Cl,Br)与H(2S)反应机理的量子化学研究

卤素二氧化物自由基(OXO)是重要的同温层物种，在极地的夜间含量尤其丰富，由于其光解产生的卤素原子会造成臭氧的严重损耗，因此愈来愈受到人们的广泛关注嘲．OXO自由基可以通过自由基之间的反应或微波放电等方式获得，有关它与其它大气物种的反应已经进行了许多研究，Bemand等在实验上研究了Cl，H，O与OClO的反应动力学，对于OBrO与H之间的反应目前尚未见实验研究的报道，只有Guhua等在理论上对部分XBrO2(X=H，Cl，Br)同分异构体进行了研究．     

CH_2CH(~2A')自由基与臭氧反应机理的理论研究

用量子化学MP2（full）方法，在6－311+ +G~(**)基组水平上研究了CH_2CH (~2A~＇)自由基与臭氧反应的机理，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QCISD（T,full）/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，研究结果表明 ：CH_2CH(~2A~＇)自由基与臭氧反应有两条可行的反应通道，分别为：CH_2CH (~2A~＇)+O_3→TS1→M1→TS2→O_2+OCH_2CH→TS4+O_2→O_2(~3∑_g)+CH_2CHO (~2A~＂)和CH_2CH(~2A~＇)+O_3→M2→TS3→O_2(~3∑_g)+CHO(~2A~＂),后一个反 应通道较容易发生，而且反应活化能小（2.97kJ/mol），说明CH_2CH(~2A~＇)自由 基与臭氧之间的反应活性很强。     

CH_2CH(~2A')自由基与臭氧反应机理的理论研究

用量子化学MP2（full）方法,在6－311+ +G~(**)基组水平上研究了CH_2CH (~2A~＇)自由基与臭氧反应的机理,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QCISD（T,full）/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,研究结果表明 ：CH_2CH(~2A~＇)自由基与臭氧反应有两条可行的反应通道,分别为：CH_2CH (~2A~＇)+O_3→TS1→M1→TS2→O_2+OCH_2CH→TS4+O_2→O_2(~3∑_g)+CH_2CHO (~2A~＂)和CH_2CH(~2A~＇)+O_3→M2→TS3→O_2(~3∑_g)+CHO(~2A~＂),后一个反 应通道较容易发生,而且反应活化能小（2.97kJ/mol）,说明CH_2CH(~2A~＇)自由 基与臭氧之间的反应活性很强。     

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。     

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。     

OXO (X=Cl,Br)与X (2P3/2)反应机理的理论研究

用密度泛函B3LYP/6-311+G^**和高级电子相关的组态相互作用QCISD(T)/6-311+G^**方法研究了OXO与X(²P_3/2)双自由基反应的微观机理.研究结果表明:该反应存在两个反应通道,产物分别为XO和X₂+O₂.由于形成产物XO的活化势垒较低,因而是主要反应通道,这与实验观察到的结果是一致的.而形成X₂+O₂的通道从动力学上看是不利的.     

N(4S)+CH3X(X=Cl、Br)反应机理的理论研究

The reaction of N(4S)+CH3X(X=Cl、Br) was studied by the ab initio method. The geometries of the reactants, transition states and products were optimized at the MP2/6-311+G(d,p) level. The corresponding vibration frequencies were calculated at the same level. The single-point calculations for all the stationary points were carried out at the MP2/6-311++G(3df,2p) and the QCISD(T)/6-311+G(d,p) levels using the MP2/6-311+G(d,p) optimized geometries. The energies of all the stationary points were calculated by the G2MP2 method. The results of this theoretical study indicate that the reaction has three reaction channels: H abstraction reaction channel a, Cl or Br abstraction reaction channel b and substitution reaction channel c. For the N(4S)+CH3Cl reaction, reaction channel a is the main reaction channel. Reaction channels b and c may have a slight contribution in the reaction. For the N(4S)+CH3Br reaction, reaction channel a is the main reaction channel. Reaction channels b and c may have some contribution in the reaction.     

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.     

Schwingungsspektren der Vinylmethylhalosilane H2C = CH(CH3)3−nSiXn (n = 1,2; X = F,Cl)

Ohne Zusammenfassung     

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     

RRKM理论研究N(4S)+CH2X(X=F,Cl)的反应通道

采用RRKM理论和疏松过渡态模型计算了N(4S)+CH2X(X=F,Cl)反应的微正则速率常数和通道分支比.计算结果表明,在较低的内能下(E=280.29 kJ/mol), N(4S)+CH2F的主要产物为NCHF+H,占总产物的59.2%,次要产物为H2CN+F,占37.4%.而N(4S)+CH2Cl反应在E＝267.78 kJ/mol时,主要产物是H2CN+Cl,占90.3%, NCHCl+H只占9.0%.在内能较高的时候(取E=500.00 kJ/mol), N(4S)+CH2F的主要通道并未变化,而N(4S)+CH2Cl的主要通道变为NCHCl+H,比例为51.5%, H2CN+Cl的比例降到40.4%.     

GeX2(X=F,Cl)与甲醛环加成反应机理的理论研究

The mechanisms of the cycloaddition reaction of singlet GeX2(X=F,Cl) with formaldehyde was studied employing the HF/6-311+G theory. The electron-correlation corrections have been further considered by the fourth-order Muller-Plesset perturbation theory (MP4SDTQ/6-311+G). The results show that this reaction proceeds in two steps: ① Difluorogemylene and formaldehyde form an intermediate complex, which is a barrierless exothermal reaction; ② the intermediate complex isomerizes to form the product, which is a rate-control step in the whole reaction. In the second step, the calculated barrier heights are 216.7 and 196.4 kJ/mol before and after considering electron-correlation effects. Compared with that of the cycloaddition reaction of difluorosilylene with formaldehyde, the cycloaddition reaction of difluorogemylene with formaldehyde is relatively slow, whereas the cycloaddition reaction of dichlorogemylene with formaldehyde can be comparable in speed.     

氮原子与卤代甲烷反应的直接氢抽提过程研究

利用B3LYP理论研究了N(~4S)+CH_3X(X = H, F, Cl)反应体系的直接氢抽提过 程,分别得到了各反应物、产物和过渡态的优化构型和谐振频率。同时应用了6- 31G(d), 6-311+G(d,p)和6-311+ + G(2d,2p)基组,考察其大小对反应体系中各物 种构型及能量的影响。理论计算表明,随着基组的增加,反应势垒逐渐降低,反应 吸热减少。对比取代甲烷的情形,结果表明反应过程中卤素原子具有典型的诱导效 应,降低了抽提势垒。     

Theoretical Study of the Reaction Mechanism and Kinetics of HO2 with XCHO (X = F,Cl)

The reactions of HO₂ with FCHO and ClCHO have been theoretically investigated by combining beyond‐CCSD(T) electronic structure benchmarks, validated density functional theory, and canonical variational transition state theory with small‐curvature tunneling, coupled‐torsions anharmonicity, and high‐frequency anharmonicity. This investigation explores three different reaction mechanisms: radical addition plus a hydrogen transfer, radical addition, and hydrogen abstraction. The calculated results show that the dominant reaction pathway is the terminal oxygen atom of HO₂ added to the carbon atom of XCHO (X = F, Cl) and simultaneously the hydrogen atom of HO₂ transferred to the oxygen atom of the C=O group in XCHO. The reaction barriers of the other reaction pathways are so high that these processes are negligible in the atmosphere. Although the barrier height of the dominant reaction pathway in the HO₂ + FCHO reaction is 0.61 kcal/mol higher than that of the corresponding HO₂ + ClCHO reaction, the HO₂ + FCHO reaction is faster than the HO₂ + ClCHO reaction because the variational effects of HO₂ + ClCHO is more obvious than that of the HO₂ + FCHO. The present results show that the HO₂ + FCHO reaction may be important in the atmosphere. The present results should be useful in evaluating the atmospheric fate of XCHO (X = F, Cl).