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2
-
2-
3-
O
O
O
+e
-
O
+e
-
+e
-
O
O
O
O
-e
-
-e
-
-e
-
O
O
O
O
neutral radical
radical dianion
diradical trianion
trioxytriangulene
Figure3.48
Spin density distributions of neutral radical, radical dianion, and diradical trianion (trioxytriangu-
lene). Unbalanced spin density distribution in the radical dianion may be caused by the distorted optimized
structurefromthreefoldsymmetricalstructure.
1.51
BPLE
0.99
IDPL
TBzD
0.78
1.00
1.34
1.10
Figure 3.49
Bis- and tris-phenalenyl systems showing amphoteric multistage redox natures. E
sum
values are
citedunderthechemicalstructures.
of molecule, is illustrated in Figure 3.50a.
73e
This multistage redox nature is understandable by the
synergistic effect of destabilization of the neutral state due to the existence of
p
-quinodimethane structure
and the stabilization of charged redox states due to the formation and aromatization of the benzene
π
system, as well as the amphoteric redox ability inherent in the phenalenyl system. Interestingly,
TBzD
,
possessing three phenalenyl moieties with a central benzene ring, shows an amphoteric six-stage redox
behavior in a solution state, although the molecule has low stability in air.
73f
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