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ESR and ENDOR investigations of phenanthrenesemiquinones
Author(s) -
Stegmann Hartmut B.,
DaoBa Hoang,
Mäurer Manfred,
Scheffler Klaus,
Buchner Hans,
Hartmann Erwin,
Mannschreck Albrecht
Publication year - 1988
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.1260260704
Subject(s) - chemistry , steric effects , solvation , thallium , coupling constant , proton , spectral line , crystallography , chemical shift , ion , stereochemistry , computational chemistry , inorganic chemistry , organic chemistry , physics , particle physics , quantum mechanics , astronomy
A series of phenanthrenesemiquinone–diphenylthallium complexes were prepared in solution from the corresponding quinones. ESR, ENDOR and TRIPLE spectra provided the proton coupling constants and the unambiguous assignment to distinct molecular positions. The thallium splitting becomes considerably less negative if the semiquinones are twisted by steric hindrance in the 4‐ and 5‐positions. On the other hand, substitution in the 1‐ and 8‐positions renders a TI more negative. These results are interpreted in terms of steric hindrance of the ion‐pair solvation.