Chemistry Reference
In-Depth Information
Fig. 17 ORTEP rendering of the X-ray crystal structure of 89, hydrogens omitted for clarity.
Reproduced with permission from [
100
]. Copyright 2007 John Wiley and Sons
TIPS
TIPS
E
(
a) MeLi
THF
"E"
93
92
Li
TIPS
Me
TIPS Me
X
(b) X
2
94a
:X=Br,71%
94b
: X = I, 64%
91
X
TIPS
(c) KC
8
K
+
95
TIPS
Scheme 25 Reactivity of DAP 91 [
101
]
Cyclic voltammetry (CV) of 91 [
102
] contained two reduction peaks, the first of
which was reversible and at a more positive potential than that of 5,10-dimethyl-
dibenzo[
a,e
]pentalene [
103
],
1.9 V (vs Ag/Ag
รพ
), respectively. Thus
the authors attempted a chemical one-electron reduction of 91 by action of potas-
sium graphite (Scheme
25
c) [
102
]. Radical anion 95 was successfully isolated as a
potassium salt and characterized by X-ray crystallography.
1.48 V and
3.2 Electrochemical and Optical Properties of Diaryl[a,e]
pentalenes
As a result of the established stability of the 10
-electron dibenzo[
a,e
]pentalene
dianion and the theoretical stability of the dication, these materials are often
observed to have amphoteric redox properties. DAPs 64a-c all undergo a reversible
p
