二氮双环阳离子游离基中N，N′—三电子键  

N, N＇-Three-electron Bond in the Radical Cation of Medium Ring Bicyclic Diamine

作　　者：邓克俭[1] 韩世刚[2] Dieter Klapsteinc 

机构地区：[1]中南民族学院化学系分析化学综合实验室 [2]西安交通大学化学化工学院 [3]Deptment of Chemistry, St. Francis Xavier University, Antigonish, N. S. ,

出　　处：《有机化学》2001年第8期618-621,共4页Chinese Journal of Organic Chemistry

摘　　要：用从头算HF/3-21+G*优化了二氮双环[m,n,l]游离基阳离子(m,n,l≥2～5).分子[4,4,4]和[2,2,2]+,[3,3,3]+,[4,4,4]+游离基阳离子的优势构型有D3对称性,而其它游离基阳离子的优势构型为非对称性.通过比较这些阳离子几何构型,HOMO和NHOMO(即Next HOMO和HOMO-1),和由MNDO计算确定的原子对作用能,表明当二氮双环游离基阳离子的桥链(CH2)n的n≥3时,桥头氮原子通过空间相互作用形成了一个弱的N,N＇-三电子σ-键.形成的三电子键强度不随环的扩大而增强.而三电子键强度被两个因素影响:一个是桥头氮原子间的p轨道重叠的取向;另一个是它们相应p轨道成分.ab initio HF/3-21 + G* calculations have been performed to optimize the structrue of a series of bicyclic diamine [ m, n, l] ( m, n, l greater than or equal to 2 similar to 5) radical cations. The calculated geometries show that neutral [ 4,4,4] and the radical cation [2,2,2](+.), [3,3,3](+.) and [4,4,4](+.) have D-3 symmetry, while the other radical cations are asymmetric. Through comparison of the geometries, HOMO and NHOMO (i.e. Next HOMO or HOMO-1) for the radical cations calculated by the ab initio 3-21 + G* method, and the atom-pair interaction energy determined by MNDO calculation, it is shown that when n is equal to or largey than 3 m the bridge chain (CH2)(n) for bicyclo diamine radical cations, the bridgehead nitrogen atoms form a weak N, N'-three-electron sigma -bond through space. The strength of the three-electron bond formed does not increase with enlargement of the ring. However, the strength was found to be influenced by two factors: One is the orientation of the overlapping p orbitals of the bridgehead nitrogen atoms the other is the component of their corresponding p orbitals.

关 键 词：二氮双环游离基阳离子 环张力效应 从头算方法 原子对作用能 取代效应 N N′-三电子键 量子化学 

分 类 号：O621.146[理学—有机化学] O621.13[理学—化学]