Acta Chimica Sinica ›› 2013, Vol. 71 ›› Issue (01): 126-132.DOI: 10.6023/A12090716 Previous Articles    


杂苯C5H5X (X=N, P, As, Sb, Bi)芳香性的核独立化学位移(NICS)与异构体稳定化能(ISE)研究

易平贵, 侯博, 汪朝旭, 刘峥军, 于贤勇, 徐百元   

  1. 湖南科技大学化学化工学院 理论化学与分子模拟省部共建教育部重点实验室 分子构效关系湖南省普通高等学校重点实验室 湘潭 411201
  • 投稿日期:2012-09-26 发布日期:2012-12-06
  • 通讯作者: 易平贵
  • 基金资助:

    项目受国家自然科学基金(No. 21172066, 20772027)、湖南省自然科学基金(No. 11JJ2007)和湖南省教育厅(No. 09K081)资助.

Study on the Aromaticity of Heterobenzenes C5H5X (X=N, P, As, Sb, Bi) by Nucleus Independent Chemical Shifts (NICS) and Isomerization Stabilization Energies (ISE)

Yi Pinggui, Hou Bo, Wang Zhaoxu, Liu Zhengjun, Yu Xianyong, Xu Baiyuan   

  1. Key Laboratory of Theoretical Chemistry and Molecular Simulation of Ministry of Education, Hunan Province College Key Laboratory of QSAR/QSPR, School of Chemistry and Chemical Engineering, Hunan University of Science and Technology, Xiangtan 411201
  • Received:2012-09-26 Published:2012-12-06
  • Supported by:

    Project supported by the National Natural Science Foundation of China (Nos. 21172066, 20772027), Hunan Provincial Natural Science Foundation (No. 11JJ2007) and the Education Department of Hunan Province (No. 09K081).

In different research fields nucleus independent chemical shift (NICS) has been used frequently as a convenient tool for obtaining information about induced dia-paratropic and paratropic ring currents, especially for the purpose of assigning aromaticity and anti-aromaticity to molecules, obviously, aromaticities and magnetic properties of molecules can be measured by NICS. This paper presents the investigation on some important features of benzene and heterobenzenes C5H5X (X=CH, N, P, As, Sb, Bi) based on the analyzing maximum value of NICS above the cycle planar about 0.8~0.9 Å. Compared with density functional theory (DFT), the calculated results by ab initio (HF) are more accurate and acceptable for the NICS of heterobenzenes. There are two primary reasons to explain the phenomenon. First, the correlation coefficient of the proton chemical shifts of 1H NMR between calculated and experimental data by HF method is larger than adopted DFT methods. Second, because the ghost position plays a critical role in judging aromaticity, only involving HF method satisfy the results through comparing NICS(1) with the aromaticity of benzene, pyridine and other heterobenzenes in normal temperature and pressure. Furthermore, according to the calculation of natural localized molecular orbitals (NLMO), we can get a conclusion that the π bonds are main contributions to the zz tensor of NICS(max), and the order is benzene>pyridine>phosphabenzene>arsabenzene>stibabenzene>bimabenzene. σ bonds all show σ aromaticity. However, other bonds' anti-aromaticity is revealed. In order to be further studied for aromaticity and chemical shifts of 1H NMR about the heterobenzenes, the magnitudes induced are depicted by the outer magnetic field. For pyridine, the magnitudes of red area coincide with the proton chemical shifts (α-H>γ-H>β-H); others are in accord with the order (α-H>β-H>γ-H). Finally, the induced magnitudes by the outer magnetic field show the same global aromaticity characteristics as NICS(max)zz and π bonds contributing to NICS(max)zz. These results all represent that the order of global aromaticity is benzene>pyridine>phosphabenzene>arsabenzene>stibabenzene>bimabenzene. Especially, the π molecular orbital excluding the X atom presents a surprising high π aromaticity. It is very useful for us to design new materials in the magnetic theory.

Key words: heterobenzenes, aromaticity, nucleus independent chemical shifts (NICS), isomerization stabilization energies, natural localized molecular orbitals