氮苄叉基苯胺及其衍生物的构象

为了探索氮苄叉基苯胺及其衍生物产生大扭角构象的根本原因,对21个分子分别在HF/6-311G^**和B3LYP/6-311G^**水平下进行了全优化和近似的势能面扫描.结果显示,分子扭曲的驱动力源于分子内的电子相互作用,片段间的核排斥作用是分子扭曲的阻力.经B3LYP/6-311G^**势能面扫描后,分别用HF,BLYP,BVWN,B3LYP和MP2法在不同的基组下对各旋转构象再作单点能运算.在简单的NBA分子中,STO-3G可以足够精确地描述分子扭曲的驱动力,但是它不能很好地描述分子内的氢键效应.

N-Benzylideneaniline-like Derivatives and Their Conformation

To discern the driving force for distorting the geometry of NBA-like species, the relax potential energy scan was performed at the B3LYP/6-311G ** level, for each molecule of 21 NBA-like species substituted with typical electron donor and/or acceptor at their benzylidene, aniline, and/or imine groups. In general, it is electron interaction, rather than nuclear repulsion between fragments, to distort a molecule away from its planar geometry, and their lowest total electronic energies occur in the geometries with the similar twist angles about 50°. Afterwards, the single point energies for 21 rotational geometries of each of two typical molecules 1 and 17 are calculated by using HF, BLYP, BVWN, B3LYP and MP2 at various Gaussian basis levels. Interestingly, STO-3G is accurate enough to understand the driving force for distorting NBA away from its planar geometry, but it is unreasonable to describe the intra-molecular hydrogen bond.