六氮苯芳香性的量子化学计算研究

Research on DFT of the Aromaticity on the Pseudo-benzene N_6 Ring

采用密度泛函方法,在B3LYP/6-311++G(d,p)水平,对六氮苯环分子进行了几何结构全优化。发现六氮苯环分子具有类似苯的键长平均化,分子结构平面化。在同键反应的基础上,用基团加和法,在B3LYP/6-311++G(d,p)水平,估算了六氮苯环的磁化率增量和各向异性磁化率,六氮苯环的磁化率增量和各向异性磁化率值都为负值。在同一水平估算了六氮苯环分子的核独立化学位移,与在同一水平上估算的苯等物质的核独立化学位移进行比较。结果都表明六氮苯环分子具有较强的芳香性。

The geometrical structure of the pseudo- benzene N6 ring was optimized at the B3LYP/6 - 311 ＋ G（d, p） level, and the equilibrium geometrical structure of the pseudo- benzene N6 ring was got. From the equilibrium geometrical structure, we can find that there were similar geometric configuration of bonds distance on average, one - dimensional model elements was between benzene and the pseudo- benzene N6 ring. On the .same bond response basis, using the group increment method, the incremental magnetism and magnetic susceptibility anisotropy of the pseudo- benzene N6 ring were calculated at the B3LYP/6- 311＋＋ G （d, p） level. The resuits showed that the incremental magnetism and the magnetic susceptibility anisotropy value were negative. The NICS values of the pseudo-benzene N6 ring were calculated at the B3LYP/6- 311 ＋ ＋ G（d,p） level and compared with the NICS values of benzene et al at the same level. The results aslo indicated that the pseudo- benzene N6 ring was the substance of better aromatic character.