Isolation and Characterization of Persistent Radical Cation and Dication of 2,7-Bis(dianisylamino)pyrene

Orbital interaction between 2,7-pyrenylene and two nitrogen redox-active centers effectively reduces the energy difference between HOMO and HOMO-1, both of which were distributed over the two nitrogen centers. In fact, one- and two-electron oxidation of 2,7-bis(dianisylamino)pyrene 3 generated a persistent radical cation and a persistent dication, respectively, and we succeeded in the isolation and single crystal X-ray structural analyses of all three oxidation states. The radical cation was considered as a spin and charge delocalized mixed-valence compound with a semiquinoidal structure. The dication was in an open-shell singlet state with a small singlet-triplet energy gap. The molecular and electronic structures for all three oxidation states of 3 were studied in comparison with the data reported for each oxidation state of closely related bis(triarylamine)s, of which structures were determined by X-ray crystallography.