A Stable [4,3]Peri‐acene Diradicaloid: Synthesis, Structure, and Electronic Properties
Jun‐Jian Shen, Yi Han, Shaoqiang Dong, Hoa Phan, Tun Seng Herng, Tingting Xu, Jun Ding, Chunyan Chi
Abstract
Abstract The synthesis of peri‐fused acenes (peri‐acenes) with two or more rows is challenging due to their intrinsic open‐shell diradical character. Herein, we report the isolation of a derivative ( 4 ) of [4,3]peri‐acene in crystalline form. The parent [4,3]peri‐acene, containing three rows of tetracene, has a large diradical character ( y 0 =94.8 %) originating from aromatic stabilization. Due to kinetic blocking, 4 showed a reasonable stability with a half‐life time of ≈157 h under ambient conditions. Its structure was determined by X‐ray crystallographic analysis, and bond‐length analysis revealed eight localized Clar's sextets. 4 exhibited an open‐shell singlet ground state with a narrow electrochemical energy gap (1.13 eV) and a small singlet–triplet energy gap (−0.57 kcal mol −1 from SQUID measurements). Its electronic properties are compared with previously reported peri‐tetracene and teranthene derivatives.