Chemistry Reference
In-Depth Information
Fig. 18 The potential energy surface for dimerization of heptacene under formation of the 4,4
0
dimer as computed at the M06-2X/6-31G*+ZPVE level of theory. Lengths of newly formed C-C
bonds are shown in
black
, energy data (in kcal mol
1
)in
red
(Gibbs free energy data,
G
,in
brackets
). Reprinted with permission from [
53
]. Copyright 2011 American Chemical Society
ʔ
O
SiR
3
39
O
1.
R
3
Si
Li
2. SnCl
2
/H
2
O
40
a
:R=
i
-Pr
b
:R=
t
-Bu
c
:R=SiMe
3
SiR
3
Fig. 19 Synthesis of silylethynyl substituted heptacenes 40 [
37
]
concentrated [
37
]. Nonetheless UV/vis-NIR and
1
H-NMR spectra could be
obtained [
37
]. The still larger SiMe
3
group (TTMSS) allowed synthesis of a
kinetically stabilized heptacene 40c that could be investigated by single-crystal
X-ray crystallography. Albeit the TTMSS groups were extensively disordered, the
aromatic part of the molecule is essentially planar (Fig.
20
)[
37
].
Heptacene 40c decomposes within a few hours when its solution is in contact
with air. The crystals, on the other hand, were reported to be stable for up to a week
when exposed to air and laboratory lighting.
