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.