Chemistry Reference
In-Depth Information
Table 1.3.
Classification of some relevant molecules discussed in
the text according to their point groups
Point group
Molecule
C
∞
v
CO
D
∞
h
H
2
,N
2
,C
2
H
2
I
h
C
60
C
s
EDT-TTF-CN, EDT-TTF-COOH
C
2
v
H
2
O, EDT-TTF,
α
-
n
T(
n
odd), DMET, MDT-TSF
C
2
h
α
-
n
T(
n
even), DMTTF, BEDT-biTTF
C
3
v
NH
3
D
2
h
TTF, TCNQ, TMTTF, TMTSF, BEDT-TTF, PTCDA,
Ni(dmit)
2
, BEDT-TSF, BDA-TTP, pentacene
D
4
h
CuPc
D
6
h
C
6
H
6
Figure 1.4. BEDT-TTF dimer in the crystal structure of neutral BEDT-TTF.
P
2
1
/
55
◦
. Crystallo-
graphic data from Kobayashi
et al
., 1986a. Dimers are contained in the (102)
plane. C and S are represented by black and medium grey balls, respectively.
c
,
a
=
0
.
661 nm,
b
=
1
.
398 nm,
c
=
1
.
665 nm,
β
=
109
.
surface than the perylene core (Hauschild
et al
., 2005). The series of unsubstituted
oligothiophenes
-
n
T exhibits
C
2
v
and
C
2
h
symmetry for
n
odd and
n
even, respec-
tively. However, for the series of end-capped EC
n
T the symmetry is reduced by
the non-planar conformation of the terminal cyclohexene rings. Hence the highest
possible symmetries are, depending on the relative conformation of the two cyclo-
hexene rings,
C
2
or
C
s
for
n
odd and
C
2
or
C
i
for
n
even. On the other hand we
observe that functionalization of TTF may result in the loss of the degree of sym-
metry, as exemplified in the series TTF (
D
2
h
)
α
→
EDT-TTF (
C
2
v
)
→
EDT-TTF-CN
(
C
s
). Functionalization will be discussed in the next chapter.
