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Radical reactions in the co‐ordinated sphere of transition metals. XIV —spin distribution of phenoxy radicals generated from biphenyldiols
Author(s) -
Pelikán P.,
Tkáč A.,
Omelka L.,
Staško A.
Publication year - 1982
Publication title -
organic magnetic resonance
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0030-4921
DOI - 10.1002/mrc.1270200403
Subject(s) - diamagnetism , chemistry , radical , unpaired electron , paramagnetism , symmetrization , dimer , spin (aerodynamics) , photochemistry , crystallography , condensed matter physics , organic chemistry , physics , mathematical analysis , mathematics , quantum mechanics , magnetic field , thermodynamics
The phenoxy radicals obtained from 2,2′‐ and 4,4′‐biphenyldiols show, in nonpolar solvents, symmetrization of the unpaired electron spin density on the two phenyl rings in the temperature range 290–410 K. Below 270 K the paramagnetic systems became diamagnetic. This para‐diamagnetic conversion with temperature is reversible. According to INDO calculations the symmetrization of spin density is due to the formation of dimeric phenoxy radicals. The para‐diamagnetic conversion at various temperatures is explained by the reversible conversion of the radical dimer to the quinone‐hydroquinone pair.