Gaussian-2 theoretical and direct ab initio molecular dynamics study of the reaction of O(3P) with thiirane, O(3P) + C2H4S(1A1)→SO(3Σ−) + C2H4(1Ag)
Gaussian-2 theoretical and direct ab initio molecular dynamics study of the reaction of O(3P) with thiirane, O(3P) + C2H4S(1A1)→SO(3Σ−) + C2H4(1Ag)
复制标题
O(3P) 与硫杂丙环反应的 Gaussian-2 理论和直接从头算分子动力学研究，O(3P) + C2H4S(1A1)→SO(3Σ−) + C2H4(1Ag)
DOI：
10.1039/a907976i
复制
发表时间：
2000
影响因子：
3.3
通讯作者：
B. Weiner
中科院分区：
文献类型：
--
作者：
Y. Ishikawa;Yuchuan Gong;B. Weiner
高斯-2
进行了理论计算和直接密度泛函分子动力学计算
在标题反应的三重势能面上对反应机理进行了表征。用Gauss2程序精确计算了O(3P)+C2H4S(1A1)势能面上的反应物、碰撞络合物、过渡态和产物的能量。最小能量路径
在三重态势能面上揭示了两种结构异构体作为碰撞络合物
大约49千卡摩尔−1
在反应物下方。这两个配合物都显示出三元环中的一个S-C键断裂。导致生成SO(3Σ−)+H_2CCH_2(1AG)的过渡态分别只在两个双自由基络合物上方2.8kcal和3.3kcal−_1处，表明它们是短暂的。
直接密度泛函分子动力学研究表明，当O(3P)接近C2H4S(1A1)的S原子时，应变硫杂环上的S-C键断裂，形成一个双自由基络合物
根据高斯-2理论预测，在20-80fs内，第二个S-C键断裂。该双自由基络合物的寿命很短，因此脱硫反应可以看作是直接模式抽提反应
反应。结合高斯-2理论和直接动力学研究的结果与最近的实验结果是一致的，即角分布是高度各向异性的(Gao等人，J.Phys。化学。A，1997年，
101,187)，且新生SO(3Σ−)产物振动态分布是倒置的
由于短暂的碰撞复合体(Ravichandran等人，Chem.太棒了。1996年，252,348)。
Gaussian-2
theoretical and direct density-functional molecular dynamics calculations have been carried
out to characterize the reaction mechanism on the triplet potential energy surface of the title reaction. The Gaussian-2 procedure is employed to determine accurately the energies of the reactants, collision complexes, transition states and products on the O(3P) + C2H4S(1A1) potential energy surface. The minimum energy pathway
on the triplet potential energy surface reveals two structural isomers as collision complexes which
lie approximately 49 kcal mol−1
below the reactants. Both of these complexes show cleavage of one of the S–C bonds in the three-membered ring. The transition states leading to formation of SO(3Σ−) + H2CCH2(1Ag) lie only 2.8 and 3.3 kcal mol−1, respectively, above the two diradical complexes, indicating that they are short-lived.
Direct density-functional molecular dynamics study indicates that, as O(3P) approaches the S atom of C2H4S(1A1), an S–C bond in the strained thiirane ring ruptures, giving rise to one of the diradical complexes
predicted by Gaussian-2 theory, followed within 20–80 fs by rupture of the second S–C bond. The diradical complex is so short-lived that the desulfurization reaction may be viewed as a direct-mode abstraction
reaction. The results of the combined Gaussian-2 theory and direct dynamics study are consistent with the recent experimental findings that angular distributions are highly anisotropic (Gao et al., J. Phys. Chem. A, 1997,
101, 187) and that nascent SO(3Σ−) product vibrational state distribution is inverted
due to short-lived collision complexes (Ravichandran et al., Chem. Phys. Lett., 1996, 252, 348).