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A Stable Trimethylenemethane Triplet Diradical Based on a Trimeric Porphyrin Fused π‐System
Author(s) -
Kato Kenichi,
Furukawa Ko,
Osuka Atsuhiro
Publication year - 2018
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201804644
Subject(s) - trimethylenemethane , diradical , porphyrin , chemistry , photochemistry , physics , singlet state , atomic physics , excited state , cycloaddition , catalysis , biochemistry
Trimethylenemethane (TMM) diradical is the simplest non‐Kekulé non‐disjoint molecule with the triplet ground state (Δ E ST =+16.1 kcal mol −1 ) and is extremely reactive. It is a challenge to design and synthesize a stable TMM diradical with key properties, such as actual aliphatic TMM diradical centers and the triplet ground state with a large positive Δ E ST value, since such species provide detailed information on the electronic structure of TMM diradical. Herein we report a TMM derivative, in which the TMM segment is fused with three Ni II meso ‐triarylporphyrins, that satisfies the above criteria. The diradical shows delocalized spin density on the propeller‐like porphyrin π‐network and the triplet ground state owing to the strong ferromagnetic interaction. Despite the apparent TMM structure, the diradical can be handled under ambient conditions and can be stored for months in the solid state, thus allowing its X‐ray diffraction structural analysis.