摘要
采用MP4(SDTQ) / 6 311++G(d ,p)和B3LYP/ 6 311++G(d ,p)对所选四种化合物进行构型优化 ,从量子拓扑学的角度对各稳定构型进行电子密度拓扑分析 ,讨论了C—S键的特性 .研究发现 :(1)类硫叶立德自由基(·CHSH2 )和硫叶立德 (CH2 SH2 )基态的稳定构型都不具有Cs 对称性 ;(2 )类硫叶立德自由基和硫叶立德中C—S键的性质类似 ,硫叶立德中π键由两个电子形成 ,类硫叶立德自由基中π键由一个电子形成 ,所以前者的π键性质明显 ,后者的π键性质不明显 ;(3)类硫叶立德自由基 (·CHSH2 )中单电子π键中的电子主要在碳原子附近运动 ,属于单电子π(C→S)配键 ,所以其C—S键的强度比相应的产物要弱 .
MP4(SDTQ)/6-311 + + G(d, p) and B3LYP/6-311 + + G(d, p) calculations were carried out to optimize the structures of S-ylide compounds. The C-S bond characters were discussed by topological analysis of the electronic density. The following conclusions are drawn: ( 1) Neither the S-ylide nor the S-ylide-like radical has C-s symmetry. (2) The C-S bond character of S-ylide-like radical is similar to that of S-ylide, there exist pi bonds in both types of ylide compounds. However, there are two electrons in the pi bond of S-ylide, while there is only one electron in the pi bond of S-ylide-like radical. (3) The electron in the pi bond of S-ylide-like radical appears mainly near the C atom. It has pi (C-->S) bond character, therefore it is weaker than the C-S bond in the corresponding product.
出处
《化学学报》
SCIE
CAS
CSCD
北大核心
2002年第9期1564-1570,共7页
Acta Chimica Sinica
基金
河北省自然科学基金资助项目
