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Syntheses and ENDOR studies of selectively deuterated galvinoxyl radicals. Complete Determination of the 13 C hyperfine coupling constants of Coppinger's radical
Author(s) -
Kirste Burkhard,
Kurreck Harry,
Sordo Magdalena
Publication year - 1985
Publication title -
chemische berichte
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 0009-2940
DOI - 10.1002/cber.19851180506
Subject(s) - chemistry , radical , hyperfine structure , deuterium , quadrupole , electron paramagnetic resonance , stereochemistry , nuclear magnetic resonance , organic chemistry , atomic physics , physics
The synthesis of selectively deuterated galvinols is described. Oxidation results in the formation of the respective galvinoxyl free radicals, e.g., Coppinger's radical and Yang's biradical. It is shown that 13 C ENDOR signals can be detected for the doublet radicals without 13 C labelling, i.e., in natural abundance. The complete set of 13 C hyperfine coupling constants of Coppinger's radical could be determined. The ENDOR study of selectively deuterated Yang's biradical in a glassy matrix allowed an unambiguous assignment of the signals to molecular positions, and conclusions with respect to the symmetry of the radical and the hindered rotation of the tert ‐butyl groups could be drawn. Randomly oriented bisgalvinoxyl biradicals in the triplet spin state give rise to sharp ENDOR lines at the free nuclear Zeeman frequencies due to NMR transitions in the M s = 0 electron spin manifold, and it is demonstrated that the respective 2 H ENDOR lines show quadrupole splittings.