Sumita Akinari, Gasonoo Makafui, Boblak Kenneth J, Ohwada Tomohiko, Klumpp Douglas A
Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan.
Department of Chemistry, Northern Illinois University, DeKalb, Illinois, USA.
Chemistry. 2017 Feb 21;23(11):2566-2570. doi: 10.1002/chem.201606036. Epub 2017 Jan 27.
A series of 9-fluorenyl cations has been studied and it is shown that increasing charge on a heterocyclic substituent group enhances the anti-aromatic character of the carbocation system. Similarly, a series of dibenzosuberenyl cations has been studied and increasing charge on a substituent group is shown to enhance aromatic character in the carbocation system. These studies include the direct observations of dicationic and tricationic species using stable-ion conditions and low temperature NMR. The structures of these ions were further characterized using DFT calculations, confirming that highly charged organic ions may exhibit unusual distributions of π-electrons and delocalization of electrons in 4n or 4n+2 π-systems.
对一系列9-芴基阳离子进行了研究，结果表明，杂环取代基上电荷的增加会增强碳正离子体系的反芳香性。同样，对一系列二苯并亚芴基阳离子进行了研究，结果表明，取代基上电荷的增加会增强碳正离子体系的芳香性。这些研究包括在稳定离子条件和低温核磁共振下对二价和三价离子物种的直接观察。利用密度泛函理论计算进一步表征了这些离子的结构，证实了高电荷有机离子可能在4n或4n + 2 π体系中表现出不寻常的π电子分布和电子离域。
