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Generation of “Sumanenylidene”: A Ground‐State Triplet Carbene on a Curved π‐Conjugated Periphery
Author(s) -
Yakiyama Yumi,
Wang Yufeng,
Hatano Sayaka,
Abe Manabu,
Sakurai Hidehiro
Publication year - 2019
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.201801802
Subject(s) - carbene , delocalized electron , conjugated system , chemistry , ground state , unpaired electron , singlet state , triplet state , alkene , moiety , photochemistry , crystallography , stereochemistry , molecule , excited state , organic chemistry , atomic physics , physics , catalysis , polymer
We have observed the generation of sumanenylidene ( 2 ), a divalent, neutral‐carbon species at the benzylic position of sumanene ( 1 ). We also clarified both experimentally and theoretically that the ground state of compound 2 was a triplet state and that its singlet–triplet energy gap (Δ E ST ) was similar to that in fluorenylidene. The curved structure of compound 2 led to slightly better spin delocalization over the two adjacent aromatic rings than in planar systems, because of the unpaired spins on the σ and π orbitals. Synthetic application of the carbene precursor, diazosumanene ( 5 ), with a variety of thiocarbonyl compounds revealed its utility for the preparation of tetrasubstituted alkene compounds (e.g., that contain a strongly electron‐donating unit) that are directly conjugated to the sumanene ( 1 ) moiety.