Analysis of the Effects of N-Substituents on Some Aspects of the Aromaticity of Imidazoles and Pyrazoles

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• 作者：Carles Curutchet ; Jordi Poater ; Miquel Sola虁 ; Jose虂 Elguero
• 刊名：Journal of Physical Chemistry A
• 出版年：2011
• 出版时间：August 4, 2011
• 年：2011
• 卷：115
• 期：30
• 页码：8571-8577
• 全文大小：878K
• 年卷期：v.115,no.30(August 4, 2011)
• ISSN：1520-5215

文摘

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 NH₂, OH, Cl, SH, H, NO₂, CN, SO₂F, SO₂CF₃, and N(SO₂CF₃)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鈥擭 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.