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Unusual Features in the ESR. Spectra of 1, 6‐Methano[ 10 ] annulene Radical Anion. A modified mcconnell equation for non‐planar π‐radicals
Author(s) -
Gerson F.,
Müllen K.,
Vogel E.
Publication year - 1971
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19710540834
Subject(s) - annulene , chemistry , planarity testing , radical , coupling constant , spectral line , ion , planar , proton , derivative (finance) , crystallography , computational chemistry , quantum mechanics , organic chemistry , physics , computer graphics (images) , computer science , financial economics , economics
ESR. spectra of the radical anions of 1, 6‐methano[ 10 ]annulene (I) and its 2,5,7,10‐tetradeuterio derivative II are reported for a temperature range of over 100°. The abnormally small magnitudes of the α‐proton coupling constants are attributed to the deviation of the tenmembered π‐perimeter from planarity; an extension of the McConnell equation is proposed to achieve agreement between theory and experiment. It is suggested that the marked temperature‐dependence of the ESR. spectra arises from slight changes in geometry which for I ⊖ should have a more pronounced effect on the α‐proton coupling constants than for planar π‐radicals.