Untersuchung der π-σ-delokalisation an den radikalionen des rubrens mit endor in lösung

From the negative and positive radical ions of rubrene (tetraphenyltetracene) ENDOR- in-solution spectra have been recorded. Proton hfs-constants could be assigned unambiguously to the various positions by also recording ENDOR spectra of partially deuterated species of this compound. The positive sign of one of the phenyl coupling constants was established by NMR measurements. The observed order |a_H^meta|? |a_H^para| = |a_H^ortho| of the phenyl proton coupling constants is in contrast to the predictions of pure π-MO-theories. These results have been interpreted by direct delocalization of the unpaired π-electron into the σ-systems of the phenyl rings. The synthesis is given for the various deuterated compounds used.