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.
CITATION STYLE
Borstelmann, J., Bergner, J., Rominger, F., & Kivala, M. (2023). A Negatively Curved π-Expanded Pyracylene Comprising a Tropylium Cation. Angewandte Chemie - International Edition, 62(46). https://doi.org/10.1002/anie.202312740
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