【摘要】 为了探索DFT方法中氮苄叉基苯胺分子的扭曲驱动力,通过把非平面氮苄叉基苯胺(NBA)分子的DFT能量分成π和σ的方法,分析了垂直离域能?EV(θ)及σ-π轨道作用能?Eσπ(θ)的失稳定性,并讨论了在扭曲过程中它们所起的作用.在B3LYP/6-31G*,6-311G*,6-31G(2d),6-311G(2d)水平下的计算结果显示:与经典观点不同,π电子的离域是失稳定的,且平面时失稳定性最强,是分子扭曲的动力;但σ-π轨道作用也是失稳定的,随着扭角的增大其失稳定性增强,是分子扭曲的阻力.NBA分子的大扭角构象,是包含π-π,σ-π轨道作用在内的各种电子相互作用共同作用的结果.更多还原

【Abstract】 In order to understand the nature of the driving force for distorting the non-planar molecule ben- zylideneaniline (NBA) away from its planar geometry, two energy effects, the vertical resonance energy ?EV(θ) and the σ-π orbital interaction energy ?Eσπ(θ), were calculated with the DFT method, and then parti- tioned into their π and σ parts, denoted as ?EV-π(θ) and ?EV-σ(θ), ?E(σπ)-π(θ) and ?E(σπ)-σ(θ) respectively. ?EV(θ) is always destabilizing, and has a tendency to distort NBA molecule away from its planar geometry as far as possible. Similarly, ?Eσπ(θ) is also destabilizing, however, it is most destabilizing at the θ=90° geometry. NBA molecule would prefer the θ=90° geometry if there were no interaction between the σ and π systems. The fact dET(θ)/dθ=0 (total energy) around θ=40° geometry, is a compromise between the vari- ous orbital interactions including π-π, σ-π interactions.更多还原