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Crystal Structure and Conductivity of a Novel Charge-Transfer Complex of N N-Dicyano-1 4-naphthoquinonediimine and Tetrathiafulvalene.

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Crystal Structure and Conductivity of a Novel
Charge-Transfer Complex of
N,N‘-Dicyano-1,4-naphthoquinonediimineand
Tetrathiafulvalene
By Alexander Aumiiller, Erich Hadicke, Siegjiried Hiinig*,
Albin Schatzle, and Jost Ulrich von Schiitz
The discovery that the CT-complex 3 formed from tetracyanoquinodimethane (TCNQ) 1 and tetrathiafulvalene
(7TF) 2”’ exhibits high electrical conductivity has stimulated the synthesis and study of numerous variants”]. Besides the introduction of substituents in 1 and 2, the heteroatoms in the donor 2 have also been exchanged (S-tSe),
with the acceptors always containing =C(CN)2 groups.
The synthesis of a new class of quinonoid acceptors in
which the =C(CN)* groups are replaced by =N-CN13], allowed the construction of novel, potentially conductive
CT-complexes (cf. Table 1).
132 8(6)
Fig. I . Bond lengths [pm] of 4 and 2 in crystalline 5 .
acceptor stacks deviate very little from each other in 5 . An
interaction between the negatively polarized N-atoms of
the acceptor 4 and the positively polarized S-atoms of the
donor 2 may be responsible for this, since the distance between these is the shortest in the stacks. The two terminal
N-atoms of one acceptor molecule 4 are so coordinated
with the S-atoms of two neighboring donor molecules 2
that the stacks form left- and right-handed helices in the
crystal (Fig. 2).
Table 1. Comparison of 3 with 5
Conductivity [W’cm-’1
Distances in stack [pml
Smallest distances between stacks [pm]
Angle between acceptor- and donor-planes
[“I
3
5
192-652 [la]
317/347 [7]
320 [7]
58.5 [7]
25
329/353
318,324
9
As first example, we describe here the CT-complex 5f41,
obtained from 2 and N,N-Dicyano-1,4-naphthoquinonediimine 4I3], which exhibits high conductivity and shows
mol/mol unpaired spins. Charan ESR signal for ca.
acteristically, the tetracyanonaphthoquinodimethane analogue of 4 does not form a CT complex with 2, apparently
due to the twisting of the molecule enforced on it by the Yshaped =C(CN)2 groups. This deformation does not take
place in the syn-configurated 4[41.Thus, 5 obeys the rules
outlined by Cowan et al.lS1for metallic conductivity of CTcomplexes, both in the case of the reaction partners and, as
shown by the crystal structure analysis, in the case of the
crystal lattice (Fig. 1).
5 consists of separated, oblique stacks of almost planar
donor and acceptor moieties, which are equidistant at
room temperature. Since the distances in the stacks are
only slightly greater than in 3[’], there are also interactions
here (distances between the moieties in solid 2 : 362 pmr7]).
Contrary to 3, the planes of the molecules in donor and
100prn
>
,
Fig. 2. Intermolecular contacts in crystalline 5 [pm]
The syn-configuration of 4 and the “inactivity” of the
unsubstituted part of the naphthalene skeleton may be responsible for the special arrangement of the stacks: Two
[*I Prof. Dr. S . Hunig, DipLChem. A. Aumiiller
Institut fur Organische Chemie der Universitat
Am Hubland, D-8700 Wiirzburg (FRG)
Dr. E. Hadicke (crystal structure analysis)
Ammoniaklabor der BASF AG, D-6700 Ludwigsbafen (FRG)
Dr. J. U. von Schutz, DipLPhys. A. Scbatzle (physical measurements)
Physikalisches Institut der Universitat (Teil 3 )
Pfaffenwaldring 57, D-7000 Stuttgart 80 (FRG)
Angew. Chem. Int. Ed. Engl. 23 (1984) No. 6
Fig. 3 . a/c Projection of the crystal lattice of 5
0 Verlag Chemie GmbH, 0-6940 Weinheim, 1984
0570-0833/84/06/)6-0449 $ 02.50/0
449
parallel, “back-to-back’’ rows containing stacks of 4 ; “on
the front side” there are two parallel rows of stacks of 2
(Fig. 3).
Figure 4 shows the temperature-dependence of the conductivity of 5 . The conductivity steadily increases with decreasing temperature down to a phase-transition temperature T,= 140 K, and then decreases by several orders of
magnitude down to 50 K. The temperature range above T,
is ascribed to metallic behavior, and that below T, to semiconducting behavior with an activation of 0.08 eV (band
gap 0.16 ev).
-
[KI
T
300
100
I
\
50
I
I
0
0
0
0
I
0
y 10-2
0
-b
s
b
O
M
0
0
i
By Roland Bosch, Gunther Jung*, Heribert Schmitt,
George M . Sheldrick, and Werner Winter*
Alamethicin and its analogues are model compounds for
the exitability of nerve membranes[’1.Voltage-dependent,
ionophoric membrane pore formers of the icosapeptide
antibiotic alamethicin-type contain numerous a-aminoisobutyric acid residues (Aib) which reduce considerably the
conformation space. In oligopeptides with Aib residues,
predominantly a tendency to form 8-turns and 3,0-helical
conformations (several consecutive 8-turns 111) is observed[21.However, the structures of alamethicid3’ and of
an N-terminal model ~ndecapeptide~~’
are a-helical. According to the flip-flop gating model“], a rigid, preferably
a-helical dipole is the only prerequisite for pore formation.
Thus lipophilic peptide segments such as the sequential
polymers Boc-(L-Ala-Aib-L-Ala-Aib-L-Ala),-OMe (n = 14) and the pentapeptide Boc-Aib-L-Ala-Aib-L-Ala-AibOMe 7 induce also voltage-dependent membrane pores
since they form conformationally stable helix-dipoles in
the lipid bilayers[”’!
I
0
\
Peptide Structures of the Alamethicin Sequence:
The GTerminal a/3,, Helical Nonapeptide and
Two Pentapeptides with Opposite 310Helicity**
0
1
Boc-Pro-Rib-Ala-Aib-Ala-OH
2 Z( Cl)-Pro-Aib-Ala-Aib-Ala-OMe
3
Tos-Aib-Aib-Rib-Aib-Aib-OMe
4
2-nib-Aib-Aib-Aib-Aib-OtBu
5
Boc-Leu-Ai b-Pro-Val-Aib-OMe
6
Z-Aib-Aib-Aib-Val-Gly-OMe
7
Boc-Aib-Ala-Aib-Ala-Aib-OMe
8
Boc-Aib-Pro-Val -Aib-Val-OMe
9
Boc-Leu-Aib-Pro-Val -Aib-Aib-Glu( 0 B z l ) -
0
0
10-5
0.005
0. 01 0
0.015
T-’ [K-’]Fig. 4. DC conductivity of 5. Four-point measurements on thin needles with
single crystal domains.
-Gln-Phc<il
The concentration of the mobile charge carriers, which
could be deduced from the intensity of the ESR signal, was
found to be ca. lo-’ spins/mol 5 , i.e. consistent with the
values recorded for other similar salts.
10
1l a
Ilb
12
Received: February 27, 1984 [Z 724 IE]
German version: Angew. Chem. 96 (1984) 439
[l] a) J. Ferraris, D. 0. Cowan, V. Walatka, Jr., J. H. Perlstein, J. Am. Chem.
Soc. 95 (1973) 948; b) L. B. Coleman, M. J. Cohen, D. J. Sandman, F. G.
Yamagishi, A. F. Garito, A. J. Heeger, Solid State Cornrnun. 12 (1973)
1125.
121 Reviews: a) J. H. Perlstein, Angew. Chem. 89 (1977) 534; Angew. Chem.
Int. Ed. Engl. 16 (1977) 519; b) P. Delhaes, G. Keryer, J. Gaultier, J. M.
Fabre, L. Giral, J . Chim. Phys. 79 (1982) 299.
131 Cf. A. Aumiiller, S. Hiinig, Angew. Chem. 96 (1984) 437; Angew. Chem.
Int. Ed. Engl. 23 (1984) 447.
141 Reaction of 4 with excess 2 in hot CH,CN afforded 5 as black, shiny
needles (up to 1 cm long), which are air-stable and gave correct analytical
data.
151 D. 0. Cowan, A. Kini, L.-Y. Chiang, K. Lerstrup, D. R. Talham, T. 0.
Poehler, A. N. Bloch, Mol. Cryst. Liq. Cryst. 86 (1982) 1.
[61 5 : monoclinic, C2/c, a=4605.8(34), b=379.6(2), c=2183.4(14) pm,
g cm-’,
@=115.76(1)”, V=3.4380x 10’ pm3, Z = 8 , p,,,=1.586
p,,,,= 50.9 cm- ; CuKa radiation (graphite monochromator), 2220 observed reflections, 1916 with Fn>20(Fn),Rs0.064, R,=0.049. Further
details of the crystal structure investigation are available on request from
the Fachinformationszentrum Energie, Physik, Mathematik, D-75 14 Eggenstein-Leopoldshafen 2, on quoting the depository number CSD
50785. the names of the authors. and the iournal citation.
[7] T. J. Kistenmacher, T. E. Phillips, D. 0. Cowan, Acta Crystallugr. 8 3 0
(1974) 763.
[S] D. Jerome, H. J . Schultz, Adu. Phys. 31 (1982) 4,299.
450
0 Verlag Chemie GmbH, 0-6940 Weinheim, 1984
-Ala-Aib-Ala-Aib-Ala-OMe
Scheme I . Aib peptides whose X-ray structures are known. Boc=terf-Butoxycarbonyl, Z(Cl) =p-Chlorobenzyloxycarbonyl, Bzl= Benzyl, Pheol = LPhenylalaninol. All chiral amino acids have L-configuration.
CAS-Registry number:
90343-29-6.
’
Boc-Pro-A i. b-Ma-Aib-OBzl
Rc-Ala -nib-Ala-OMe
Boc-Ala-Aib-Ala-OMe
Boc-Ala-Ai b-A1 a-Aib-Ala-Glu ( O B z l ) -
In the following, we wish to describe interesting helical
structures of the synthetic segments of naturally occurring
membrane pore formers: 1 with a 3io-helix (N-terminal
alamethicin sequence 2-6), and 7 . 2 H 2 0 with a 3;o-helix
(N-terminal suzukacillin A sequence 1-5)‘’“’, as well as the
c~/3,~-helical
structure of the C-terminal alamethicin nonapeptide 12-20 9 (Scheme 1).
[”I
Prof. Dr. G. Jung, Prof. Dr. W. Winter [‘I, Dr. R. Bosch,
Dr. H. Schmitt
Institut fur Organische Chemie der Universitat
Auf der Morgenstelle 18, D-7400 Tiibingen (FRG)
Prof. Dr. G. M. Sheldrick
Anorganisch-chemisches lnstitut der Universitat
Tammannstrasse 4, D-3400 Gottingen (FRG)
[ ‘1 Present address: Forschungwentrum der Griinenthal GmbH, Ziegler-
strasse 6, D-5100 AdChen (FRG)
[**I This work was supported by the Deutsche Forschungsgemeinschaft
(SFB 76) and by the Fonds der Chemischen Industrie.
0570-0833/84/0606-0450 $02.50/0
Angew. Chem. Int. Ed. Engl. 23 (1984) Nu. 6
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crystals, structure, complex, tetrathiafulvalene, transfer, novem, conductivity, naphthoquinonediimine, charge, dicyano
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