具有自由基对特性分子的密度泛函理论研究  

A density function study on the molecules possessing radical pair characteristics

作　　者：曹阳[1] 蔡春[1] 吕春绪[1] 周新利[1] 罗军[1] 袁淑军[1] 

机构地区：[1]南京理工大学化工学院,江苏南京210094

出　　处：《分子科学学报》2003年第1期1-7,共7页Journal of Molecular Science

基　　金：教育部博士点基金资助项目(BJ9701);江苏省自然科学基金资助项目(BK99071)

摘　　要：　用密度泛函理论在B3LYP/6-311++G 水平下研究了9种具有自由基对特性分子.从结构上看,它们由两个游离自由基耦合形成.耦合后原自由基的键长、键角以及振动频率数值改变不大,但这些分子中不再具有未成对电子以及由此产生的其他性质.新形成的共价健的键长一般较长,易于断裂并导致分子分解.初步研究了苯分子硝化反应的初始过程,当进攻试剂为NO+2时,反应生成了C6H+6-NO2自由基对,当进攻试剂不为NO+2时,反应生成了游离自由基.Nine kinds of molecules possessing radical pair characteristics were studied by density functional theory at B3LYP/6-311++G**level.To the geometries,they were formed by the coupling two free radicals,and the original bond lengths,angles and vibrational frequencies were not changed much,but unpaired electrons and the properties generated from them were no longer found in these radical pairs.The new-formed covalent bond lengths were longer than ordinary ones,which may lead to the cleavage of the bond and the dissociation of radical pair molecules.The radical pair that may be formed during the first stage of benzene nitration was studied.It shows that when the nitrating agent is NO+2,an C6H+6-NO2radical pair may formed,but when nitrating agent is not NO+2,free radicals may be found in the reacting system.

关 键 词：密度泛函理论 自由基 自由基对 自旋密度 结构 原子电荷 量子化学 振动频率 键长 键角 

分 类 号：O641.121[理学—物理化学]