Title: Stable Diindeno‐Fused Corannulene Regioisomers with Open‐Shell Singlet Ground States and Remarkable Diradical Characters

Author: Ru-Qiang Lu  Shuang Wu  Lin-Lin Yang  Wen-Bin Gao  Hang Qu  Xiao-Ye Wang  Jun-Bo Chen  Chun Tang  Hai-Yan Shi  Xiao-Yu Cao

Abstract: 

Synthesis of open‐shell polycyclic hydrocarbons with large diradical characters is challenging due to their high reactivity. Herein, two diindeno‐fused corannulene regioisomers DIC‐1 and DIC‐2, curved fragments of fullerene C104, were synthesized, exhibiting open‐shell singlet ground states. The incorporation of the curved and non‐alternant corannulene moiety within diradical systems leads to significant diradical characters as high as 0.98 for DIC‐1 and 0.89 for DIC‐2. Such high diradical characters can presumably be ascribed to the re‐aromatization of the corannulene π system. Although DICs have high diradical characters, they display excellent stability under ambient conditions. The half‐lives are 37 days for DIC‐1 and 6.6 days for DIC‐2 in solutions. This work offers a new design strategy towards diradicaloids with large diradical characters yet retaining high stability.

Full-Link: https://onlinelibrary.wiley.com/doi/10.1002/anie.201902028