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| Abstract: |
| B3LYP calculations of density functional theory with the 6-311 + G（3df，2p）basis set level are used to investigate the equilibrium structures and intramolecular rearrangement reaction between the linear HSSH and branched H2SS isomers. The predicted geometrical parameters and scaled harmonic vibrational frequencies for HSSH are in good agreement with the available values experimentally. The predicted S-S and S-H bond lengths in the thiosulfoxide structure H2SS are 0.1986 and 0.1366 nm respectively and the values of 5SSH and 5HSH bond angles are 108. 3o and 89. 5o respectively. The transition-state for the unimolecular isomerization is suitably characterized by diagonalizing the matrix of energy second derivatives to determine the unique imaginary vibrational frequency and confirmed by the IRC calculation. The calculated results show that the linear structure is stable with respect to the branched form（lower 109.8 kJ/mol corrected with zero point vibrational energy）energetically. The calculated energy barrier for the direct intramolecular hydrogen atom transfer isomerization process is 190.3 kJ/mol. The kinetic results demonstrate that the isomerization is a unimolecular process，but the reaction rate is pretty slow. This agrees with the thermodynamical results. So the isomerization process should proceed via the other likely processes. |
| Key words: H2S2,Isomerization,Density functional theory,Transition-state theory |
| FundProject: |
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| H2S2的构型及其异构化反应的密度泛函理论研究 |
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陈文凯*,杨迎春,章永凡,丁开宁,李俊篯
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| 摘要: |
| 采用量子化学中的密度泛函理论B3LYP方法,在6-311+G(3df,2p)水平上,全优化得到了H2S2线型和分叉型两种异构体的平衡结构,讨论了分叉型异构体存在的可能性,同时对可能发生的分子内原子迁移过程的过渡态进行了考察,并采用内禀反应坐标(IRC)加以证实.计算结果表明,从能量角度看,线型的HSSH为稳定构型.热力学和动力学的计算则表明,分子内的原子转移需要较高的活化能,并且速度很慢,分叉型异构体存在的可能性较小. |
| 关键词: H2S2 密度泛函理论 异构化 过渡态理论 |
| DOI：10.1088/1674-0068/17/4/421-425 |
| 分类号: |