Azoniadibenzo[a,j]phenalenide: A Polycyclic Zwitterion with Singlet Biradical Character

• Published in: Angewandte Chemie International Edition Vol. 58; no. 19; pp. 6415 - 6419
• Main Authors: Arikawa, Shinobu, Shimizu, Akihiro, Shintani, Ryo
• Format: Journal Article
• Language: English
• Published: WEINHEIM Wiley 06.05.2019
• Subjects: aromaticity; Chemistry; Chemistry, Multidisciplinary; density-functional calculations; Physical Sciences; polycycles; radicals; Science & Technology; zwitterions; density-functional calculations; zwitterions; radicals; aromaticity; polycycles; INDEPENDENT CHEMICAL-SHIFTS
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.201902006

A polycyclic zwitterion, azoniadibenzo[a,j]phenalenide, having a singlet biradical character, was synthesized and isolated for the first time. The negative charge was found to be delocalized over the periphery of the main core of the zwitterion and the positive charge was localized near the nitrogen atom. Its singlet biradical character was confirmed by a small HOMO–LUMO energy gap with their spatial overlap, and observation of thermally excited triplet species together with DFT calculations. Mind the gap: A polycyclic zwitterion with singlet biradical character was synthesized and isolated for the first time. The negative charge is delocalized over the periphery of the main core and the positive charge is localized near the nitrogen atom, confirming the zwitterionic nature. A small HOMO–LUMO energy gap with their spatial overlap and the observation of thermally excited triplet species together with DFT calculations confirmed the singlet biradical character.