Cyclopenta Ring Fused Bisanthene and Its Charged Species with Open‐Shell Singlet Diradical Character and Global Aromaticity/ Anti‐Aromaticity

• Published in: Angewandte Chemie International Edition 2017-09, Vol.56 (38), p.11415-11419
• Main Authors: Wang, Qing, Gopalakrishna, Tullimilli Y., Phan, Hoa, Herng, Tun Seng, Dong, Shaoqiang, Ding, Jun, Chi, Chunyan
• Format: Article
• Language: English
• Subjects: annulenes; Aromatic hydrocarbons; Aromaticity; density functional calculations; Ground state; Helium; Hydrocarbons; polycycles; radicals
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.201704805

Cyclopenta ring fused bisanthene and its charged species were synthesized. The neutral compound has an open‐shell singlet ground state and displays global anti‐aromaticity. The dication also exhibits singlet diradical character but has a unique [10]annulene‐within‐[18]annulene global aromatic structure. The dianion is closed‐shell singlet in the ground state and shows global aromaticity with 22 π electrons delocalized on the periphery. These findings prrovide new insight into the design and properties of global aromatic/anti‐aromatic systems based on π‐conjugated polycyclic hydrocarbons. Good character: Cyclopenta ring fused bisanthene (middle) was facilely synthesized and shows global anti‐aromaticity with moderate diradical character. The dication exhibits a unique [10]annulene‐within‐[18]annulene structure with an open‐shell singlet ground state, while the dianion is a closed shell and displays a diatropic ring current on the π‐conjugated periphery.