What Is the Preferred Structure of the Meisenheimer−Wheland Complex Between sym-Triaminobenzene and 4,6-Dinitrobenzofuroxan?

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• 作者：Peng Jin ; Fengyu Li ; Kevin Riley ; Dieter Lenoir ; Paul v. R. Schleyer ; Zhongfang Chen
• 刊名：Journal of Organic Chemistry
• 出版年：2010
• 出版时间：June 4, 2010
• 年：2010
• 卷：75
• 期：11
• 页码：3761-3765
• 全文大小：790K
• 年卷期：v.75,no.11(June 4, 2010)
• ISSN：1520-6904

文摘

The geometries, energies, and electronic properties of possible configurations of Meisenheimer−Wheland (M−W) complexes of sym-triaminobenzenes and 4,6-dinitrobenzofuroxan (DNBF) were investigated theoretically by MP2 and a variety of DFT methods. The π−π complex is preferred thermodynamically by more than 15 kcal/mol over the σ-complexes for the unsubstituted species. However, the N-substituents of the 1,3,5-triaminobenzenes influence the relative stabilities of the alternative configurations significantly. The σ-syn configuration of the M−W complex of 1,3,5-tris(N-piperidyl)benzene and DNBF has the lowest energy, followed closely by the σ-anti and π−π forms. The small energy differences between different configurations are consistent with the dynamic interconversion of three homomeric structures observed experimentally by NMR. The ca. 1.63 Å C−C interring bond exchanges among three equivalent sites. Quantum theory of atoms in molecules (QTAIM) analysis provided insights into the nature of the intermonomer interactions. Charge transfer and σ bonding account for the stability and remarkably large binding energies of the M−W complexes.