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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 Spositions. On the other hand, substitution in the 1and &positions renders uT, more negative. These results are interpreted in terms of steric hindrance of the ion-pair solvation.
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## Abstract Proton‐hyperfine data are reported for the radical anions generated from azulene (1) and its alkyl derivatives 2–11 in 1,2‐dimethoxyethane both ‘chemically’ with K and electrolytically. The alkyl derivatives are 1,3‐dimethyl‐ (2), 5,7‐dimethyl‐ (3), 1,3,5,7‐tetramethyl‐ (4), 2‐methyl‐ (
I4N-and 'H-Coupling constants, determined by ESR, ENDOR, and general-TRIPLE-resonance spectroscopy, are reported for the radical cations of tetrazinodi(heteroarenes) 1-8. The results comply with the expectation that donor properties of these compounds are mainly due to the electron-rich dihydrotetra