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ClONO2异构化反应和分解反应的理论研究
Theoretical Study of Isomerization and Decomposition Reactions of ClONO2
【摘要】 用B3LYP/6 31+G(d)和MP2 (Full) /6 31+G(d)优化ClONO2 及其分解反应和异构化反应的过渡态和产物的分子结构 .在B3LYP/6 31+G(d)水平上计算了相关分子的振动频率 .ClONO2 的几何结构、振动频率和红外强度与实验测量值符合得很好 .找到了未曾报道的立体异构体 .对这一立体异构体进行了高级别理论方法CCSD(T) /6 311G(d)和QCISD(T) /6 311G(d)的几何结构优化和振动频率计算 ,表明它是一个稳定的立体异构体 .在所研究的几种反应中 ,ClONO2 分解为NO2 +ClO是最容易进行的反应 .而ClONO2 异构为立体异构体的反应是最难进行的反应 .其所需克服的过渡态的能垒为 4 81.5 2kJ/mol,而反应吸收能量为 2 99.85kJ/mol.次难进行的是ClONO2 经TS1到反应中间体M1,再经TS12而分解为ClNO +O2 的反应 .这个反应通道所需克服过渡态的能垒为 4 2 1.5 5kJ/mol,反应吸收能量为 15 7.98kJ/mol.从以上分析可知 ,和ClO +NO2 反应生成ClONO2 比较 ,ClONO2 具有较好的稳定性 .
【Abstract】 The potential energy surface for the decomposition and isomerization of Chlorine Nitrate (ClONO2) is calculated using the G3 theory. Geometries of related species are optimized at the MP2(full)/6-31+G(d) and B3LYP/6-31+G(d) level. Vibrational frequencies and IR intensities of ClONO2 have been calculated at the same level. Obtained geometries and vibrational frequencies as well as IR intensities for ClONO2 are in good agreement with experimental values. A new stable stereoisomer is verified by CCSD(T) and QCISD(T) methods at 6-311G(d) basis set. Calculated geometries using above methods for this stereoisomer are in accord with each other. The calculated reaction heat of ClONO2 are also in good agreement with the available data in the literature. Among these reactions of ClONO2, the stereoisomer reaction is the hardest one. The barrier height for this reaction is 481.52 kJ/mol relative to ClONO2 and the reaction is endothermic by 299.85 kJ/mol. On the other hand, among these unimolecular reactions of ClONO2, the decomposition reaction of NO2 +ClO is the easiest one. These results indicate that ClONO2 is very stable.
【Key words】 Potential energy surface; G3 theory; Stereoisomer; ClONO2;
- 【文献出处】 化学物理学报 ,Chinese Journal of Chemical Physics , 编辑部邮箱 ,2004年06期
- 【分类号】O611
- 【被引频次】1
- 【下载频次】61