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ESR spectroscopy of some dicyano‐, pyrazino‐ and quinoxalino‐1,3,2‐dithiazolyl radicals
Author(s) -
Chung YuenLi,
Fairhurst Shirley A.,
Gillies Duncan G.,
Kraft Gregor,
Krebber Angelika M. L.,
Preston Keith F.,
Sutcliffe Leslie H.,
Wolmershäuser Gotthelf
Publication year - 1992
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.1260300814
Subject(s) - chemistry , radical , spectroscopy , computational chemistry , nuclear magnetic resonance spectroscopy , nuclear magnetic resonance , photochemistry , stereochemistry , organic chemistry , quantum mechanics , physics
Several symmetrical 1,3,2‐dithiazol‐2‐yl radicals have been examined that have in common nitrogen‐containing substituents at the 4‐ and 5‐positions, namely 4,5‐dicyano‐1,3,2‐dithiazol‐2‐yl, [ 15 N 2 ]‐1,3,2‐dithiazolo [4,5‐ b ] pyrazin‐2‐yl and 1,3,2‐dithiazoleo [4,5‐ b ] quinoxalin‐2‐yl. The ESR spectrum of the 4,5‐dicyano radical does not reveal any 14 N splittings from the cyanide groups; however, the pyrazine and the quinoxaline derivatives do have multi‐lined well resolved spectra arising from substantial hyperfine interactions with these nuclei. The interactions are sufficiently large to be observed in the powder spectra of the latter. The presence of proton hyperfine interactions shows that unpaired‐electron spin density is delocalized over all the rings. It has been found that the radicals attached to pyrazine and quinoxaline can be incorporated into single crystals of naphthalene and phenazine, respectively.