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Crystalline Diradical Dianions of Pyrene‐Fused Azaacenes
Author(s) -
Chen Chao,
Ruan Huapeng,
Feng Zhongtao,
Fang Yong,
Tang Shuxuan,
Zhao Yue,
Tan Gengwen,
Su Yuanting,
Wang Xinping
Publication year - 2020
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.202001842
Subject(s) - diradical , chemistry , pyrene , singlet state , photochemistry , triplet state , computational chemistry , molecule , organic chemistry , excited state , atomic physics , physics
Although diradicals and azaacenes have been greatly attractive in fundamental chemistry and functional materials, the isolable diradical dianions of azaacenes are still unknown. Herein, we describe the first isolation of pyrene‐fused azaacene diradical dianion salts [(18‐c‐6)K(THF) 2 ] + [(18‐c‐6)K] + ⋅ 1 2−.. and [(18‐c‐6)K(THF)] 2+ ⋅ 2 2−.. by reduction of the neutral pyrene‐fused azaacene derivatives 1 and 2 with excess potassium graphite in THF in the presence of 18‐crown‐6. Their electronic structures were investigated by various experiments, in conjunction with theoretical calculations. It was found that both dianions are open‐shell singlets in the ground state and their triplet states are thermally readily accessible owing to the small singlet–triplet energy gap. This work provides the first examples of crystalline diradical dianions of azaacenes with considerable diradical character.