草酰氯一价正离子构象及其碳—碳键反应活性的理论研究 |
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引用本文: | 沈红玉,孙成科,李宗和. 草酰氯一价正离子构象及其碳—碳键反应活性的理论研究[J]. 化学学报, 2003, 61(8): 1220-1225 |
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作者姓名: | 沈红玉 孙成科 李宗和 |
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作者单位: | 北京师范大学化学系,北京,100875 |
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基金项目: | 国家自然科学基金(No.29773007)资助项目. |
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摘 要: | 用密度泛函方法BHandHLYP在6-311+G(d)和6-311+G(2df)水平上对草酰氯 的一价正离子[(ClCo)_2~+]作了构象分析,结果表明,(ClCo)_2~+具有平面 反式和交叉式两种稳定构象,交叉构象存在超共轭现象,此外,对草酰氯离子、中 性分子各解离通道初级反应的Gibbs自由能的计算,发现草酰氯离子C—C键解离通 道的反应活性大于中性分子,对该通道进一步做了反应机理研究,证实了热力学结 论,并且与实验相一致,对草酰氯离子的振动频率和键耦合常数的研究表明其碳— 碳键解离具有选键性。
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关 键 词: | 密度泛函理论 草酰氯 热力学 构象 |
修稿时间: | 2002-12-12 |
Theoretical Study on the Conformers and the C-C Bond Reaction Activity of Oxalyl Chloride Cation |
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Affiliation: | The Chemistry Department of Beijing Normal University |
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Abstract: | The conformers of oxalyl chloride have been extensively studied both theoretically and experimentally while the structure of its cation [(ClCO) + 2] has received less attention. On the other hand, the theoretical study on the single molecule dissociation of oxalyl chloride cation is a whole new aspect. In the present work, the conformers of oxalyl chloride cation was studied at the BHandHLYP level with 6-311+G(d) and 6-311+G(2df) basis sets. It is found that (ClCO) + 2 have gauche and trans conformers. The orbital interactions in the gauche conformer make it possible to stabilize itself. The C-C bonds in both of the conformers are longer than that in the oxalyl chloride neutral molecule, which suggests in advance that C-C bond in (ClCO) + 2 can have some different properties from that in (ClCO) 2. According to the reaction Gibbs free energy calculated at the BHandHLYP/6-311+G(2df) level, the dissociation of C-C bond in (ClCO) + 2 is easier than that in (ClCO) 2. The reaction mechanism confirms this thermodynamic conclusion which is in accord with the experimental results. The frequencies of all the vibrant modes in (ClCO) + 2 and the coupling constants between the C-C bond vibrancy and other vibrant modes are also studied. The results indicate that (ClCO) + 2 bears bond selectivity in C-C bond dissociation. It suggests that it is possible to excite the vibrancy of C-C bond to a high level with selected laser light, and so that C-C bond can break down at this level. |
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Keywords: | DFT oxalyl chloride cation bond-selective reaction |
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