N-芳硫基-1,4-苯醌亚胺的Z,E-异构化机理：二维核磁共振和密度泛函理论研究

Z,E-isomerization mechanism for N-arylthio-1,4-benzoquinonimines: DNMR and DFT investigations.

作者信息

Pirozhenko V V, Rozhenko A B, Avdeenko A P, Konovalova S A, Santalova A A

机构信息

Institute of Organic Chemistry, National Academy of Sciences of Ukraine, 5 Murmanskaya Str. Kiev, 02660, Ukraine.

出版信息

Magn Reson Chem. 2008 Sep;46(9):811-7. doi: 10.1002/mrc.2254.

DOI:10.1002/mrc.2254

PMID:18636468

Abstract

Z,E-isomerization has been investigated for the series of the N-arylthio-1,4-benzoquinonimines using a line shape analysis in the (1)H NMR spectra. Thermodynamic parameters and substituent effects have been analyzed for the isomerization process. It has been shown based on the DFT (B3LYP) calculations that the dynamic transformation for N-arylthio-1,4-benzoquinonimines should be considered as a combination of the two different processes, a rotation about the N-S bond and an inversion at nitrogen via the transition state with the linear C=N-S moiety. The free energies of activation for the isomerization (DeltaG(298 K)) measured experimentally depend on the substitution in the quinonimine moiety and phenyl ring and can be referred either to the inversion of the nitrogen atom or to the hindered rotation about the N-S bond.

摘要

通过对N-芳硫基-1,4-苯醌亚胺系列化合物的¹H NMR谱进行线形分析，研究了Z,E-异构化。对异构化过程的热力学参数和取代基效应进行了分析。基于密度泛函理论（DFT，B3LYP）计算表明，N-芳硫基-1,4-苯醌亚胺的动态转化应被视为两个不同过程的组合，即围绕N-S键的旋转和通过具有线性C=N-S部分的过渡态在氮原子处的反转。实验测得的异构化活化自由能（ΔG(298 K)）取决于醌亚胺部分和苯环上的取代情况，并且可以归因于氮原子的反转或围绕N-S键的受阻旋转。