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在MPW1PW91/6-311G(d,p)水平上优化了标题反应各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QCISD(T)/6-311G(d,p)方法对所有驻点及反应路径的部分选择点进行单点能校正,分别构建了CH3SO+HO2反应体系的单、三重态反应势能剖面.研究结果表明,CH3SO+HO2反应体系存在6条反应通道7条路径,优势通道(1)R→3IM→P1(CH3SOH+3O2)发生在三重态势能面上,此通道包含两条路径,其表观活化能分别为12.01和-30.04kJ?mol-1,主路径(2)R→3IM→3TS2→P1(CH3SOH+3O2)是一个无势垒氢迁移过程.利用经典过渡态理论(TST)与变分过渡态理论(CVT)并结合小曲率隧道效应模型(SCT),分别计算了主路径(2)在200～2500K温度范围内的速率常数kTST,kCVT和kCVT/SCT,在此温度区间内的表观反应速率常数三参数表达式为kCVT/SCT=4.08×10-24T3.13exp(8012.2/T)cm3imolecule-1is-1,具有负温度系数效应.速率常数计算结果显示,变分效应在计算温度段内影响较小,而量子力学隧道效应在低温段有显著影响.
The geometric configurations of each stationary site species for the title reaction are optimized at the MPW1PW91 / 6-311G (d, p) level and analyzed for transition state structure and connectivity at the same level by frequency calculation and intrinsic reaction coordinate (IRC) The single point and single point corrections of all sites and reaction path selection points were performed by QCISD (T) / 6-311G (d, p) method, and the single and triplet reactions of CH3SO + HO2 reaction system were constructed respectively Potential energy cross section.The results show that there are 6 paths in CH3SO + HO2 reaction system, the dominant channel (1) R → 3IM → P1 (CH3SOH + 3O2) occurs on the triplet potential energy surface and this channel contains two paths, The apparent activation energies are 12.01 and -30.04 kJ? Mol-1, respectively, and the main path (2) R → 3IM → 3TS2 → P1 (CH3SOH + 3O2) is a barrierless hydrogen transfer process.Using the classical transition state theory ) And variational transition state theory (CVT) combined with the small curvature tunneling effect model (SCT), the rate constants kTST, kCVT and kCVT / SCT of the main path (2) in the temperature range of 200-2500 K were calculated respectively. The three-parameter expression of apparent reaction rate constant in the interval is kCVT / SCT = 4.08 × 10-24T3.13exp (8012.2 / T) cm3imolecule-1is-1 Negative temperature coefficient effects. The results show the rate constant, variation in the calculation of the temperature effect less affected segment, and the quantum mechanical tunnel effect has a significant influence on the low temperature section.