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Consequences of Triplet Aromaticity in 4 n π‐Electron Annulenes: Calculation of Magnetic Shieldings for Open‐Shell Species
Author(s) -
Gogonea Valentin,
Schleyer Paul von Ragué,
Schreiner Peter R.
Publication year - 1998
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/(sici)1521-3773(19980803)37:13/14<1945::aid-anie1945>3.0.co;2-e
Subject(s) - annulene , aromaticity , open shell , chemistry , computational chemistry , molecular physics , physics , atomic physics , molecule , organic chemistry
The triplet states of 4 n π‐electron annulenes , as suggested by Baird in 1972, should be regarded as aromatic rather than antiaromatic. Such triplet states show planarized, symmetrical geometries (see C 9 H 9 + on the right), much lower energies than corresponding acylic triplet reference species, and evidence for diatropic ring currents (nucleus‐independent chemical shifts and magnetic susceptibility exaltations).