SIOC English
化学学报
高级检索

化学学报 ›› 1997, Vol. 55 ›› Issue (8): 747-754. 上一篇    下一篇

研究论文

环丙基硅烯的理论研究: 环丙基硅烯C3H5SiH的重排反应及其机理

冯圣玉;冯大诚;邓从豪   

  1. 山东大学理论化学研究室
  • 发布日期:1997-08-15

Theoretical studies of cyclopropylsilylenes-the rearrangement of cyclopropylsilylene C3H5SiH

FENG SHENGYU;FENG DACHENG;DENG CONGHAO   

  • Published:1997-08-15

PDF

887

本文用限制的Hartree-Fock解析梯度方法在3-21G和6-31G^*水平上对环丙基硅烯的重排反应及其机理进行了从头算研究。以6-31G^*优化构型作了二级微扰计算, 并计算了各构型的频率。在此基础上得到了重排反应的热焓△H, 自由能△G和平衡常数K, 用Eyring过渡态理论计算了反应的速度常数k(T), 应用Woodward-Hoffmann规则讨论了环丙基硅烯重排反应过程中端基的旋转机理。结果表明, 环丙基硅烯经过113.4kJ/mol的势垒扩环重排为硅杂环丁烯为自发反应; 而其1,2-氢迁移重排反应热垒为190.0kJ/mol, 是非自发反应, 难于进行,不能与扩环重排相竞争。另外, 扩环重排反应可分为多步过程, 每步的端基旋转均可用Woodward-Hoffmann规则说明。

关键词: 反应机理, 重排反应, 动力学分析, 过渡态理论, 环丙基硅烯

The rearrangement of cyclopropylsilylene C3H5SiH have been studied by ab initio molecular orbital theory at 3-21G and 6-31G* levels. Correlation energy corrections were computed with using second-order Moller-Plesset perturbation theory (MP2). The enthalpy △H, free energy △G, equilibrium constant K, and reaction rate constant k(T) in Eyring transition state theory of cyclopropylsilylene C3H5SiH have also been calculated. These results show that the ring expansion of cyclopropylsilylene C3H5SiH to silacyclobutene is easy to occur with a barrier of 113.4kJ/mol, while the 1,2-H shift is not competitive to the ring expansion for its much higher barrier. The rearrangement is divided into several steps and each step can be explained with Woodward-Hoffmann rule.

Key words: REACTION MECHANISM, REARRANGEMENT REACTION, KINETIC ANALYSIS, TRANSITION STATE THEORY

中图分类号: