Use of Charge-Charge Repulsion to Enhance [pi]-Electron Delocalization into Anti-Aromatic and Aromatic Systems

• Published in: Chemistry : a European journal Vol. 23; no. 11; p. 2566
• Main Authors: Sumita, Akinari, Gasonoo, Makafui, Boblak, Kenneth J, Ohwada, Tomohiko, Klumpp, Douglas A
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 21-02-2017
• Subjects: Chemistry
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.201606036

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.