Department of Theoretical and Structural Chemistry, University of Łódź, Łódź, Poland.
J Comput Chem. 2011 May;32(7):1441-8. doi: 10.1002/jcc.21730. Epub 2011 Jan 27.
Cyclooctatetraene in its dianionic form (COT(2-)) is considered to be partially or fully aromatic due to the fact that, unlike its neutral counterpart, it adopts planar structure with CC bonds equalized. However, some authors report that this dianion is neither planar nor aromatic. Thus, we performed a detailed analysis of the COT(2-) case. The influence of several technical parameters on the result of calculations on COT(2-) was investigated. It appears from our analysis that the use of some specific level of approximation may lead to very misleading results in which the COT ring occurs in its neutral structure, in fact being neither planar nor aromatic. Additionally, our results may suggest that COT(2-) dianion is rather an artificial structure (being the result of specific basis set description) and should not occur in experimental conditions.
环辛四烯二负离子（COT(2-)）的形式被认为是部分或完全芳香的，因为与中性对应物不同，它采用平面结构，CC 键等长。然而，一些作者报告说，这种二负离子既不是平面的也不是芳香的。因此，我们对 COT(2-)进行了详细的分析。研究了几个技术参数对 COT(2-)计算结果的影响。我们的分析表明，使用某些特定的近似水平可能会导致非常误导的结果，其中 COT 环出现在其中性结构中，实际上既不是平面的也不是芳香的。此外，我们的结果可能表明 COT(2-)二负离子是一种人为结构（是特定基组描述的结果），在实验条件下不应出现。
