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Aromaticity of pericyclic reaction transition structures: magnetic evidence
Author(s) -
Jiao Haijun,
Schleyer Paul von Ragué
Publication year - 1998
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/(sici)1099-1395(199808/09)11:8/9<655::aid-poc66>3.0.co;2-u
Subject(s) - pericyclic reaction , delocalized electron , aromaticity , chemistry , electron delocalization , ring (chemistry) , chemical shift , computational chemistry , character (mathematics) , transition state , resonance (particle physics) , chemical physics , atomic physics , molecule , organic chemistry , physics , geometry , mathematics , catalysis
The transition states of thermally allowed pericyclic reactions are aromatic. They not only have highly delocalized structures and large resonance stabilizations (energies of concert), but also strongly enhanced magnetic susceptibilities (Λ) and appreciable NICS (nucleus‐independent chemical shifts) values arising from the diatropic ring currents. Aromaticity is the consequence of cyclic electron delocalization, which can have σ and hybrid, and not just π character. © 1998 John Wiley & Sons, Ltd.