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131.
132.
He Bian Honghong Zhang Ling Pei Qian Wang Fang Wang Yun Zhang Jinshe Chen 《International journal of quantum chemistry》2020,120(8):e26146
Density functional theory was adopted in this work to reveal the reaction mechanism of CH2SH with HO2. Reaction rate constants were computed from 200 to 2000 K using the transition state theory combined with Wigner and Eckart tunneling correction. Moreover, localized orbital locator, atoms in molecules and Mayer bond order analyses were used to study the essence of chemical bonding evolution. Eleven singlet paths and three triplet ones are located on the potential surface (PES). The results show that the main products on the singlet PES are 1CH2S and H2O2, whereas on the triplet PES they are CH3SH + 3O2, which are coincident with the similar reaction of CH3S and HO2. This conclusion is also supported by rate constant calculation results. Interestingly, all the possible paths are involved in the hydrogen transfer. The results have provided underlying insights to the analogous reactions and further experimental studies. 相似文献
133.
Fatima Ijjaali Manuel Alcamí Otilia M Manuel Yez 《International journal of quantum chemistry》2002,86(1):130-137
The singlet and triplet potential energy surfaces involved in N++SH2 reactions have been explored using high‐level ab initio techniques. The geometries of the stationary points were optimized at the QCISD/6‐311G(df,p) level. The final energies were obtained in CCSD(T)/6‐311+G(3df,2p) single‐point calculations. The results obtained show that, although the N+(1D)+SH2 entrance channel is higher in energy than the N+(3P)+SH2 one, most of the [H2, S, N]+ singlet state cations are lower in energy than the corresponding triplets, due to their different bonding characteristics. Both singlet and triplet potential energy surfaces are quite close each other, and crossover between them can occur. The minimum energy crossing points were located by means of CASSCF(6,5) calculations. The spin‐orbit couplings show that the transition probability from the triplet to the singlet potential energy surface is significantly large. One of the most important consequences is that some of the products of the reaction, such as SH+, can be formed in typical spin‐forbidden processes. Since all the relevant structures along these pathways are much lower in energy than the reactants, this mechanism should be accessible even at low impact energies and therefore could be important in processes taking place in interstellar media. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001 相似文献
134.
在B3LYP/6-311++G(2df,p)水平上优化了标题反应驻点物种的几何构型, 并在相同水平上通过频率计算和内禀反应坐标(IRC)分析对过渡态结构及连接性进行了验证. 采用双水平计算方法HL//B3LYP/6-311++G(2df,p)对所有驻点及部分选择点进行了单点能校正, 构建了CH2SH+NO2反应体系的单重态反应势能剖面. 研究结果表明, CH2SH与NO2反应体系存在4条主要反应通道, 两个自由基中的C与N首先进行单重态耦合, 形成稳定的中间体HSCH2NO2 (a). 中间体a经过C—N键断裂和H(1)—O(2)形成过程生成主要产物P1 (CH2S+trans-HONO), 此过程需克服124.1 kJ8226;mol-1的能垒. 中间体a也可以经过C—N键断裂及C—O键形成转化为中间体HSCH2ONO (b), 此过程的能垒高达238.34 kJ8226;mol-1. b再经过一系列的重排异构转化得到产物P2 (CH2S+cis-HONO), P3 (CH2S+HNO2)和P4 (SCH2OH+NO). 所有通道均为放热反应, 反应能分别为-150.37, -148.53, -114.42和-131.56 kJ8226;mol-1. 标题反应主通道R→a→TSa/P1→P1的表观活化能为-91.82 kJ8226;mol-1, 此通道在200~3000 K温度区间内表观反应速率常数三参数表达式为kCVT/SCT=8.3×10-40T4.4 exp(12789.3/T) cm38226;molecule-18226;s-1. 相似文献