| Abstract: | 13C-NMR. Spectra of 3H-benzcd]azulenc-3-ones 13C-NMR. Spectra of 7,9-dimethyl-3H-benzcd]azulenc-3-one ( 2 ) and 7,9-dimethyl-4,5-dihydro-3H-benzcd]azulene-3-one ( 7 ) in CDCl3 and CF3CO2D are reported. The assignment of signals was achieved with the aid of selective proton decoupling, non-decoupled spectra and comparison with spectra of simple azulene-derivatives. The major localization of positive charge in the cationic 3-hydroxybenz-cd]azulenium system was found in the six- and seven-membered ring, which suggests in accordance with calculated π-electron densities the structure of a benztropylium ion rather than a bridged azulenium ion. |
