Department of Chemistry, University of Warsaw, Warsaw, Poland.
J Mol Model. 2011 Jun;17(6):1427-33. doi: 10.1007/s00894-010-0844-z. Epub 2010 Sep 17.
The reasons behind changes of aromaticity in 10 unsubstituted aza-azoles were analysed by employing the natural bond orbital (NBO) approach at the MP2/6-311+G(d,p) level of theory. Sum of occupations of p(z) orbitals at atoms in the ring correlates well with the magnetism based aromaticity index NICS as well as with the number of nitrogen atoms in the ring. Changes of NICS depend strongly in a linear way on the number of NN bonds. Classification of azoles based on the number of pyridine-type nitrogen atoms vicinal to NH is supported by plotting the relative occupation of π orbitals (π(occ)) against the relative occupation of σ orbitals (σ(occ)) for all individual atoms in rings.
采用自然键轨道（NBO）方法在 MP2/6-311+G(d,p)理论水平上分析了 10 个未取代的氮杂氮杂环戊二烯芳香性变化的原因。环中原子的 p(z)轨道占据数之和与基于磁的芳香性指数 NICS 以及环中氮原子数很好地相关。NICS 的变化强烈地以线性方式依赖于 NN 键的数量。基于与 NH 相邻的吡啶型氮原子数对唑类进行分类，通过绘制所有环中单个原子的π轨道（π（occ））相对占据数与σ轨道（σ（occ））相对占据数的关系得到支持。
