Institut de Química Computacional and Departament de Química, Universitat de Girona, Campus de Montilivi, 17071 Girona, Spain.
J Phys Chem A. 2011 Aug 4;115(30):8571-7. doi: 10.1021/jp204263p. Epub 2011 Jul 14.
The influence of the N-substituent on the aromaticity of azoles is a subject that has not yet been addressed in detail, in contrast to the good understanding of the corresponding C-substitution. In the present work, we analyze the aromaticities of a series of 1,2- and 1,3-azoles (pyrazoles and imidazoles, respectively) with the N-substituents NH(2), OH, Cl, SH, H, NO(2), CN, SO(2)F, SO(2)CF(3), and N(SO(2)CF(3))(2), which are also compared with the aromaticities of the corresponding substituted benzene series. The larger stabilitiy of the imidazole ring is due not to a higher aromaticity, but rather to the weakness of the N-N bond in the pyrazole series. The aromaticity of azoles was found to be significantly less robust to N-substitutions than that of their C-substituted benzene counterparts.
唑类化合物的 N-取代基对其芳香性的影响尚未得到详细研究，而相应的 C-取代基的芳香性已得到很好的理解。在本工作中，我们分析了一系列 1,2-和 1,3-唑类化合物（分别为吡唑和咪唑）的芳香性，这些化合物的 N-取代基为 NH(2)、OH、Cl、SH、H、NO(2)、CN、SO(2)F、SO(2)CF(3)和 N(SO(2)CF(3))(2)，并与相应取代的苯系列的芳香性进行了比较。咪唑环的较大稳定性不是由于更高的芳香性，而是由于吡唑系列中 N-N 键的较弱性。与 C-取代基的苯相比，唑类化合物的芳香性对 N-取代基的稳定性要差得多。
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