A negatively curved π-expanded pyracylene comprising a tropylium cation

• Verfasst von: Borstelmann, Jan [VerfasserIn]
• Verfasst von: Bergner, John [VerfasserIn]
• Verfasst von: Rominger, Frank [VerfasserIn]
• Verfasst von: Kivala, Milan [VerfasserIn]
• Titel: A negatively curved π-expanded pyracylene comprising a tropylium cation
• Verf.angabe: Jan Borstelmann, John Bergner, Frank Rominger, and Milan Kivala
• E-Jahr: 2023
• Jahr: 22 September 2023
• Umfang: 7 S.
• Fussnoten: Gesehen am 13.11.2023
• Titel Quelle: Enthalten in: Angewandte Chemie. International edition
• Ort Quelle: Weinheim : Wiley-VCH, 1998
• Jahr Quelle: 2023
• Band/Heft Quelle: 62(2023), 46, Artikel-ID e202312740, Seite 1-7
• ISSN Quelle: 1521-3773
• DOI: doi:10.1002/anie.202312740
• Datenträger: Online-Ressource
• Sprache: eng
• Sach-SW: Aromaticity
• Sach-SW: Cation
• Sach-SW: Curvature
• Sach-SW: Electron Acceptor
• Sach-SW: Pyracylene
• K10plus-PPN: 187014788X

Abstract

We disclose π-expanded pyracylenes and their cationic species comprising 7-membered rings. The compounds were synthesized by stepwise oxidative cyclodehydrogenation to monitor the effect of successive cyclization on the structural and optoelectronic properties. As shown by X-ray crystallography, the complete cyclization leads to a boat-shaped scaffold featuring negative curvature provided by the 7-membered ring. The embedded tropone unit enabled the convenient generation of a stabilized tropylium cation, showing bathochromically shifted absorption bands reaching into the near-infrared region beyond 1000 nm. The altered structural features, supported by theoretical calculations, point towards the positively charged 7-membered ring having aromatic character.