文献类型：期刊文献

中文题名：Is Free Cyclooctatetraene Dianion an Aromatic System? A Quantum Chemistry Study

英文题名：Is Free Cyclooctatetraene Dianion an Aromatic System? A Quantum Chemistry Study

作者：Cao Tingting[2];Ma Yipei[2];Yan Xiuhua[3];Cheng Jiagao[1];Luo Youhua[2];He Liming[2];Zhu Weiliang[2,3]

机构：[1]E China Univ Sci & Technol, Sch Pharm, Shanghai Key Lab Chem Biol, Shanghai 200237, Peoples R China;[2]E China Univ Sci & Technol, Sch Sci, Shanghai 200237, Peoples R China;[3]Shanghai Inst Mat Med, Drug Discovery & Design Ctr, Shanghai 201203, Peoples R China

年份：2009

卷号：27

期号：10

起止页码：1914

中文期刊名：中国化学（英文版）

外文期刊名：CHINESE JOURNAL OF CHEMISTRY

收录：;WOS:【SCI-EXPANDED(收录号:WOS:000271755900012)】；

基金：Project supported by the National Natural Science Foundation of China (Nos. 20572117 and 20802018) and the Natural Science Foundation of Shanghai (No. 08ZR1406500).Equally contributing to this work.

语种：英文

外文关键词：cyclooctatetraene; aromaticity; NICS; HOMA; dianion

摘要：To investigate whether free cyclooctatetraene dianion (COT2-) is aromatic, quantum chemistry methods were used to optimize its structure. based on the optimized structures, the natural population analysis (NPA) charge, bond order, delocalization energy, nucleus-independent chemical shift (NICS), and harmonic oscillator model of aromaticity (HOMA) values were computed by DFT-B3LYP method with basis set 6-311 + +G**, which shows that COT2- is not aromatic as it is not planar and has different bond lengths and bond orders, smallest delocalization energy and positive NICS values. To further confirm the finding, the changes of NICS and energy against ring distortion angle were scanned. The COT2- has positive NICS values all along the angle from 180 degrees to 120 degrees while other aromatic systems always have negative values. The energy scanning suggests that COT2- should have the weakest capability to maintain its planar structure. All the calculations strongly indicate that COT2- is not aromatic. This study also suggests that NICS scan might be a good approach to judge aromaticity.