Tetrafluoro and dichloro derivatives of thiophene-fused DCNQI- and TCNQ-type acceptors: A synthetic, electrochemical and crystallographic study

Article abstract of DOI:10.1039/a601628f

Novel thiophene-fused DCNQI derivatives 8 and 11 bearing four fluorine atoms have been obtained in good yield from the corresponding quinones by reaction with bis(trimethylsilyl)carbodiimide (BTC). The presence of four fluorine atoms leads to good accepto

Full text of DOI:10.1039/a601628f

Tetrafluoro and dichloro derivatives of thiophene-fused DCNQI- and TCNQ-type
acceptors: a synthetic, electrochemical and crystallographic study
´
Nazario Mart´ın,*,a Pilar de Miguel,a Carlos Seoane,*,a Armando Albertb and Felix H. Canob
aDepartamento de Quımica Orga´nica I, Facultad de Quımica, Universidad Complutense, 28040-Madrid, Spain
´
´
bDepartamento de Cristalografıa, Instituto de Quımica Fısica ‘Rocasolano’ (CSIC), Serrano 119, 28006-Madrid, Spain
´
´
´
Novel thiophene-fused DCNQI derivatives 8 and 11 bearing four fluorine atoms have been obtained in good yield from the
corresponding quinones by reaction with bis(trimethylsilyl)carbodiimide (BTC). The presence of four fluorine atoms leads to good
acceptor molecules which form charge transfer complexes in solution with N,N∞-tetramethyl-p-phenylenediamine. The effect of
chlorine atoms on the crystal packing in the analoguous thiophene-fused TCNQ derivatives 3a and 3b is also reported.
Tetracyano-p-quinodimethane (TCNQ) and dicyano-p-quino-
diimine (DCNQI) have been used most widely as acceptors1
for the preparation of novel charge transfer complexes (CTC)
and charge transfer salts.2
to the less sterically demanding cyanoimino group in compari-
son with the dicyanomethylene fragment. In a previous paper5b
we carried out a comparative crystallographic study of com-
pounds of this type and important differences in terms of
planarity and crystal packing were found due to the highly
distorted geometry in 3a. Considering the effect that substitu-
ents can play on the stacking pattern, we have determined the
X-ray structure of compound 3b bearing two chlorine atoms.
On the other hand, the electron acceptors containing ben-
zene-fused TCNQ and DCNQI derivatives 1 and 2, prepared
from 9,10-anthraquinone,3,4 do not form CTC when they are
mixed with donor molecules such as tetrathiafulvalene (TTF).
This is due to their poor acceptor ability and, particularly, the
highly distorted structure of 1. Although the same result was
found for the acceptors 3 and 4 obtained from 4,9-dihydronaph-
tho[2,3-b]thiophene-4,9-dione, the condensation of a thio-
phene ring instead of a benzene ring resulted in a more planar
molecule.5
Results and Discussion
The synthesis of the novel p-extended DCNQI-type derivatives
8 and 11 was carried out from the corresponding halogeno-
substituted quinones 7 and 10 by reaction with bis(trimethylsi-
lyl)carbodiimide (BTC) by following Hunig’s procedure
¨
(Scheme 1).7 The quinones 7 and 10 were prepared from
tetrafluorophthalic anhydride 5 by reaction with benzene and
aluminium trichloride to yield the corresponding 2-benzoyl-
3,4,5,6-tetrafluorobenzoic acid 6 which, by treatment with
concentrated sulfuric acid at 100 °C, led to the 1,2,3,4-tetra-
fluoroanthraquinone 7. In a similar way, the reaction of
anhydride 5 with thienyllithium in diethyl ether at −78 °C
yielded the acid 9 which, after treatment with PCl and AlCl
5
3
in dry nitrobenzene gave the novel 5,6,7,8-tetrafluoro-4,9-
dihydronaphtho[2,3-b]thiophene-4,9-dione 10 (see Experi-
mental section). An alternative procedure for the preparation
of substituted naphtho[2,3-b]thiophenediones by microwave
assisted cyclization of substituted 2-thienylcarbonylbenzoic
acids, catalysed with clays in dry media, has been recently
described.8
Compounds 8 and 11 can exist as the syn and anti isomers.
The presence of isomers in other DCNQI analogues has been
previously established by NMR spectroscopy4 and molecular
mechanics analyses.9 The high resolution 1H NMR spectrum
of compound 8 shows a sharp doublet of doublets at d 7.93
and a broad signal at d 8.67 due to the rapid isomerization of
the cyanoimino group at room temperature. This fact could
be accounted for by the similar steric hindrance of hydrogen
and fluorine peri atoms, resulting in a non-favoured configur-
ation.4,9 Accordingly, compound 11 showed a sharp doublet
at d 8.09 and another at d 8.80 suggesting a favoured configur-
ation with the cyano groups towards the thiophene ring, in
agreement with the previously reported X-ray data for the
unsubstituted compound 4a.5b
Taking into account the strong effect of fluorine or chlorine
atoms on the acceptor capacity,6 we have carried out the
synthesis of novel DCNQI acceptors 8 and 11 derived from
9,10-anthraquinone and 4,9-dihydronaphtho[2,3-b]thiophene-
4,9-dione bearing four fluorine atoms on the benzene ring. The
geometry of these DCNQI-type acceptors may present greater
planarity than the corresponding TCNQ-type analogues, due
Cyclic voltammetric (CV) measurements of compounds 8
and 11, as well as the starting quinones 7 and 10, were carried
out in CH Cl at room temperature using tetrabutylammonium
2
2
perchlorate as the supporting electrolyte. The data obtained
are summarized in the Table 1. All compounds showed two
J. Mater. Chem., 1997, 7(1), 25–29
25

Table 1 Cyclic voltammetry data of acceptors
compound
E
1/V
E
2/V
DE log K
1/2
1/2
1a
2a
−0.20 (2e−)
−0.11
−0.46
0.35
5.93
3aa
3bb
4ab
4bb
7c
−0.18 (2e−)
−0.10 (2e−)
−0.11
−0.04
−0.72
−0.61
−0.50
−1.23
0.50
0.46
0.51
0.31
0.51
0.46
8.62
7.93
8.79
5.34
8.79
7.93
8c
−0.19 (−0.19)b
−0.57
−0.50 (−0.48)b
−1.08
10c
11c
0.00
−0.46
DCNQIc
0.21
−0.41
0.62 10.68
a CH Cl /Bu N+BF −/Pt vs. Ag/AgCl/MeCN (refs. 4, 5).
2
2
4
4
Fig. 1 Cyclic voltammetry of compound 8 (scan rate 50 mV s−1)
b MeCN/Bu N+ClO −/glassy
carbon
vs.
Ag/Ag+
(ref. 6).
4
4
c CH Cl /Bu N+BF −/glassy carbon vs. SCE; scan rate 50 mV s−1.
2
2
4
4
found for compounds 8 and 11 clearly confirm these trends,
and the thiophene-containing compound 11 exhibits a first
reduction potential which is shifted 190 mV to more positive
values (Table 1).
one-electron reduction waves to the corresponding anion-
radical and dianion (Fig. 1). Replacing the benzene ring with
a thiophene ring leads to a better acceptor due to the lowering
of the steric hindrance. The presence of four fluorine atoms as
substituents on the benzene ring significantly decreases the
reduction potential values. The reduction potential values
Increasing benzannulation with regard to the parent DCNQI
leads to a decrease in the acceptor ability and also to a
diminishing of the thermodynamic stability of the correspond-
ing radical-anions (lower log K values10 in Table 1). Thus,
compound 8 exhibits the least stable radical-anion due to the
stronger steric interaction between the cyano group and the
peri-hydrogens.
Unlike the non-fluorine substituted analogues, compounds
8 and 11 show evidence of complexation when they were
mixed, in equimolecular amounts in dichloromethane under
inert atmosphere, with the strong donor N,N,N∞,N∞-tetra-
methyl-p-phenylenediamine (TMPD). Although solid stable
CTCs were not isolated, a colour change was observed.
The UV–VIS spectra of the reaction solution, under argon
atmosphere, showed a typical low-energy charge-transfer
band (8ΩTMPD: l =538 nm; 11ΩTMPD: l =545 nm).
max
max
Attempts to form CT-complexes with acceptor 11, which
showed the best acceptor ability in this study, with other
donors such as tetrathiafulvalene (TTF) did not afford the
corresponding solid CT-complex. A weak broad band was
observed at around 450 nm in the electronic spectrum which
might indicate the presence of a very low energy CT-band in
solution. These findings are also in agreement with those
previously reported for the poorer electron-acceptor dithio-
phene-fused TCNQ {4,8-bis(dicyanomethylene)-4,8-dihydro-
benzo-[1,2-c:4,5-c∞]dithiophene}11 which, in contrast to the
other isomers, did not form a CT-complex with TTF. Finally,
attempts to form a metal salt were carried out by reaction of
acceptors 8 and 11 with copper iodide in acetonitrile under
inert atmosphere. A black solid precipitate was only obtained
with 8, which showed the IR stretching cyano band at
2177 cm−1. According to the elemental analysis, a rather
unusual 155 acceptor–copper stoichiometry was found.
The molecular structures of compounds 3b and the unsubsti-
tuted analogue 3a are shown in Fig. 2, together with the atomic
numbering scheme. The main geometrical features of the
common moiety of both compounds are quite similar, and
only bond distances and angles involving atoms of the thio-
phene ring show significant differences (Table 2). This effect
could be due to an artifact of the disorder which both molecules
possess. Thus, the presence of the two chlorine atoms in
compound 3b does not affect significantly the conformation of
this molecule. Both compounds present a butterfly shape
centred at the two substituted carbon atoms, with an
interplanar angle between the S(1)–C(2)–C(3)–C(4)–C(5)–
C(12)–C(13) and C(5)–C(6)–C(7)–C(8)–C(9)–C(10)–C(11)–
C(12) planes of 147.5° (1) for compound 3b and 149.7° (1) for
compound 3a. This distortion from planarity has been
accounted for by the steric hindrance between the cyano
Scheme 1 Reagents and conditions: i, C H , AlCl ; ii, H SO ;
6
6
3
2
4
iii, Me SiN=C=NSiMe , TiCl , CH Cl ; iv, 2-thienyllithium, then
3
3
4
2
3
2
NH Cl, HCl; v, PCl , C H NO , AlCl
4
5
6
5
2
26
J. Mater. Chem., 1997, 7(1), 25–29

Table 2 Geometrical features of compounds 3a
˚
bond lengths/A
3b
3a
S(1)–C(2)
S(1)–C(13)
C(2)–C(3)
1.80(1)
1.648(3)
1.37(1)
1.541(5)
1.462(4)
1.393(6)
1.465(5)
1.36(1)
1.469(5)
1.405(6)
1.29(1)
1.31(1)
—
1.68(2)
1.66(2)
1.30(6)
C(3)–C(4)
1.46(6)
C(4)–C(5)
1.458(4)
1.391(5)
1.471(5)
1.373(5)
1.383(5)
1.415(4)
1.399(6)
1.388(5)
1.713(4)
1.380(5)
1.719(4)
1.392(5)
1.468(5)
1.454(5)
1.362(5)
1.425(6)
1.435(5)
1.150(6)
1.141(6)
1.441(5)
1.433(6)
1.133(6)
1.139(6)
C(4)–C(13)
C(5)–C(6)
C(5)–C(14)
C(6)–C(7)
C(6)–C(11)
C(7)–C(8)
C(8)–C(9)
C(8)–Cl(24)
C(9)–C(10)
C(9)–Cl(25)
C(10)–C(11)
C(11)–C(12)
C(12)–C(13)
C(12)–C(19)
C(14)–C(15)
C(14)–C(17)
C(15)–N(16)
C(17)–N(18)
C(19)–C(20)
C(19)–C(22)
C(20)–N(21)
C(22)–N(23)
1.265(6)
—
1.484(5)
1.469(4)
1.453(4)
1.363(5)
1.432(7)
1.430(5)
1.142(7)
1.152(5)
1.436(5)
1.440(5)
1.140(5)
1.144(6)
bond angles/degrees
C(2)–S(1)–C(13)
93.1(3)
114.1(5)
105.4(5)
115.4(4)
124.9(4)
119.7(3)
122.4(3)
114.6(3)
122.8(3)
119.0(3)
125.3(4)
115.7(3)
121.7(4)
122.6(5)
—
94(1)
S(1)–C(2)–C(3)
113(3)
C(2)–C(3)–C(4)
110(4)
C(3)–C(4)–C(13)
C(3)–C(4)–C(5)
112(3)
128(3)
Fig. 2 Molecular structure of compounds (a) 3a and (b) 3b, showing
C(5)–C(4)–C(13)
C(4)–C(5)–C(14)
C(4)–C(5)–C(6)
120.3(3)
122.3(3)
114.4(3)
123.3(3)
118.8(3)
122.2(3)
119.0(3)
120.8(3)
119.4(4)
117.0(3)
123.6(3)
120.7(4)
120.5(3)
118.8(3)
120.0(4)
119.9(4)
121.1(3)
118.9(3)
122.9(3)
113.9(3)
122.9(3)
119.1(3)
130.9(4)
109.9(4)
124.2(4)
123.3(4)
112.4(4)
175.8(4)
176.2(5)
122.3(3)
123.2(4)
114.0(3)
175.9(5)
178.5(5)
the atomic numbering
C(6)–C(5)–C(14)
C(5)–C(6)–C(11)
C(5)–C(6)–C(7)
groups and the peri hydrogens. This butterfly shape of the
molecules 3a and 3b with a boat type quinonoid group was
also found in 11,11,12,12-tetracyano-9,10-anthraquinodime-
thane (TCAQ).12 Different isomeric benzodithiophene ana-
logues of TCAQ have also been obtained and their electronic
and steric properties were found to depend on the mode of
fusion of the two thiophene units to the central TCNQ ring.11
The crystal structures of these thiophene-fused TCNQs showed
a more planar butterfly shape, in comparison with the TCAQ
molecule.
C(7)–C(6)–C(11)
C(6)–C(7)–C(8)
C(7)–C(8)–C(9)
C(7)–C(8)–Cl(24)
C(9)–C(8)–Cl(24)
C(8)–C(9)–C(10)
C(8)–C(9)–Cl(25)
C(10)–C(9)–Cl(25)
C(9)–C(10)–C(11)
C(6)–C(11)–C(10)
C(10)–C(11)–C(12)
C(6)–C(11)–C(12)
C(11)–C(12)–C(19)
C(11)–C(12)–C(13)
C(13)–C(12)–C(19)
C(4)–C(13)–C(12)
S(1)–C(13)–C(12)
S(1)–C(13)–C(4)
C(5)–C(14)–C(17)
C(5)–C(14)–C(15)
C(15)–C(14)–C(17)
C(14)–C(15)–N(16)
C(14)–C(17)–N(18)
C(12)–C(19)–C(22)
C(12)–C(19)–C(20)
C(20)–C(19)–C(22)
C(19)–C(20)–N(21)
C(19)–C(22)–N(23)
—
122.3(5)
—
—
122.2(4)
115.4(3)
124.9(3)
119.7(3)
122.4(3)
114.4(3)
123.2(3)
120.0(3)
128.2(3)
111.8(3)
124.0(4)
124.0(4)
111.6(4)
174.1(5)
175.9(5)
123.5(4)
124.8(4)
111.7(4)
175.4(5)
177.2(5)
On the other hand, crystal packing is severely modified
(Fig. 3). Compound 3b shows aromatic interactions, forming
dimers and Cl,N13 contacts in the crystal packing, and with
˚
a contact Cl(25),Cl(24) (x−1/2, y, 1/2−z) of 3.461 (2) A.
However, compound 3a presents the aromatic interactions as
the main intermolecular contacts, forming a stacking pattern
along the (2 0 1) direction with tight packing. Thus it seems
that, here again, the chlorine atoms, when competing with the
rings interactions, play a role in the packing.
Both molecules 3a and 3b present structural disorder, con-
sisting of the superposition of two ordered structures related
by a pseudo mirror plane through C(2) and the mid-point of
C(8)–C(9). The population factors were 0.53–0.47(1) and
0.72–0.298(1) for both compounds 3b and 3a, respectively,
thus showing the symmetrizing effect of the chlorine atoms.
The disorder was constrained in the refinement so as to fit the
pseudo mirror plane with the populations equal to 1.
a Both compounds present disorder. Distances and angles are given
In conclusion, we have carried out the synthesis, electro-
chemical and crystallographical study of some novel halogen-
containing acceptors. The presence of four fluorine atoms is
responsible for the greater acceptor ability of 8 and 11 as
shown by the cyclic voltammetry study. The reasonably good
first reduction potentials, in addition to the expected planar
for the major structure.
J. Mater. Chem., 1997, 7(1), 25–29
27

1.56 g cm−3, F(000)=760, m=49.44 cm−1. Refined cell param-
eters were obtained from setting angles of 72 reflections. A
prismatic brown crystal (0.30×0.25×0.15 mm) was used for
the analysis.
Data collection. Automatic four circle diffractometer Philips
PW 1100 with graphite oriented monochromated Cu-Ka radi-
ation. The intensity data were collected using the v–2h scan
mode with 2<h<65°; two standard reflections were measured
every 90 min with no intensity variation. A total of 2743
reflections were measured and 2286 were considered as
observed [I>3s(I)]. The data were corrected for Lorentz and
polarization effects.
Structure solution and refinement. The structure was solved
by direct methods using SIR8814 and DIRDIF.15 Hydrogen
atoms were calculated and fixed in the final mixed refinement;
isotropic thermal parameters of these atoms were considered
as fixed contributors. A convenient weighting scheme was
applied16 to obtain no dependence in ꢀwD[14]Fꢁvs.ꢀF ꢁ and
0
ꢀsin h/lꢁ. The final R (Rw) value was 5.9 (7.4). Atomic
scattering factors for the compound were taken from
International Tables for X-Ray Crystallography17 and calcu-
lations were performed using XRAY80,18 XTAL,19 HSEARC20
and PARST.21
Fig. 3 Crystal packing for (a) compound 3a along the axis perpendicu-
lar to the (2 0 1) direction and (b) compound 3b along the a axis.
Aromatic interactions are represented with dashed lines.
Atomic coordinates, thermal parameters, and bond lengths
and angles have been deposited at the Cambridge
Crystallographic Data Centre (CCDC). See Information for
Authors, J. Mater. Chem., 1996, Issue 1. Any request to the
CCDC for this material should quote the full literature citation
and the reference number 1145/15.
geometry for compounds 8 and 11, are responsible for the
complexation observed in the UV–VIS spectra when they are
in solution in the presence of N,N,N∞,N∞-tetramethyl-p-pheny-
lenediamine. Although these novel acceptors did not form CT-
complexes with TTF, a copper CT-salt was formed with
compound 8. On the other hand, the presence of halogen
atoms also plays an important role in the crystal packing, as
observed in the intermolecular interactions of the related
compounds 3a and 3b. These data indicate that although the
presence of fluorine atoms increases the acceptor ability in
these aryl-fused DCNQI derivatives, they are not strong
enough acceptors to form CT-complexes with molecules which
form stable radical-cation such as TTF. The presence of
halogen atoms on molecules containing two five-membered
heterocyclic rings fused to the central TCNQ and DCNQI
acceptors should lead to stronger acceptors with more planar
geometries.
2-Benzoyl-3,4,5,6-tetrafluorobenzoic acid 6
This compound was obtained from tetrafluorophthalic anhy-
dride, benzene and AlCl by following the standard Friedel–
3
Crafts procedure.22 Yield 70%; mp 177 °C (from water) (Calc.
for C H F O : C, 56.39; H, 2.03. Found: C, 56.42; H, 2.12%);
14 6 4
3
d (300 MHz, [2H ]DMSO) 7.41–7.89 (5H, m, ArH), 14.20
H
6
(1H, br s, CO H); n (KBr)/cm−1 3000, 1715 (CNO, acid),
2
max
1680 (CNO), 1630, 1600, 1590, 1530, 1470, 1440, 1370, 1320.
2-(2-Thienylcarbonyl)-3,4,5,6-tetrafluorobenzoic acid 9
2-Thienyllithium (4.6 ml; 1.0  in tetrahydrofuran) was slowly
added to a mixture of tetrafluorophthalic anhydride (1 g,
4.54 mmol) in dry diethyl ether (15 ml) at −20 °C. The mixture
was maintained under argon and allowed to warm to room
temperature, then stirred for 24 h. The cold reaction mixture
containing the lithium complex was decomposed by the
Experimental
General
addition of saturated NH Cl (30 ml) and then acidified with
4
6  HCl. The organic layer was separated and the aqueous
Melting points were determined using a Gallenkamp melting
point apparatus and are uncorrected. IR spectra were recorded
on a Perkin-Elmer 398 spectrometer. UV spectra were recorded
on a Perkin-Elmer Lambda-3 instrument. 1H NMR spectra
were determined with a Varian XL-300S spectrometer and J
values are given in Hz. Elemental analyses were performed on
a Perkin-Elmer CHN 2400 apparatus.
phase washed with diethyl ether; the organic extracts were
washed with saturated brine and water, and treated with 5%
sodium hydrogen carbonate (3×50 ml). The aqueous alkaline
layers were collected, cooled and acidified by the dropwise
addition of 6  HCl with vigorous stirring. The keto acid
which precipitated was filtered and washed free of the mineral
acid with water. The crude product was crystallized from
boiling water. Yield 60%; mp 175 °C (Calc. for C H F O S:
Cyclovoltammetric measurements were performed on a EG
& PAR Versastat potentiostat using 250 electrochemical analy-
sis software. A Metrohm 6.084.C10 glassy carbon electrode
was used as indicator electrode in voltammetric studies.
Tetrafluorophthalic anhydride, 2-thienyllithium, titanium
tetrachloride and bis(trimethylsilyl)carbodiimide (BTC) are
commercially available.
12 4 4
3
C, 47.38; H, 1.33. Found C, 47.60; H 1.35%); d (300 MHz,
H
CDCl ) 7.14 (1H, dd, J 3.9 and 4.8, H-4-thiophene), 7.43 (1H,
3
d, J 3.9, H-5-thiophene), 7.80 (1H, dd, J 4.8 and 1.2 H-3-
thiophene); n (KBr)/cm−1 3200, 1750 (CNO, acid), 1640
max
(CNO), 1520, 1480, 1420, 1370, 1300.
X-Ray crystallographic measurements
1,2,3,4-Tetrafluoroanthraquinone 7
Crystal data for compound 3b. C H N S Cl , MW=
Compound 7 was obtained by treatment of 6 (1 g, 3.3 mmol)
with conc. sulfuric acid (5 ml) at 100 °C. The reaction mixture
was cooled and poured into ice–water, and the product was
18
4 4 1 2
379.222, monoclinic, P2 /c, a=9.229 (1), b=19.609 (4), c=
1
˚
˚
9.457 (1) A, b=109.29°, V=1615.4 (4) A, Z=4, D =
C
28
J. Mater. Chem., 1997, 7(1), 25–29

collected by filtration to yield an orange solid. Yield 85%; mp
nitrile was transferred via cannula under argon atmosphere to
a boiling solution of CuI (77 mg, 0.4 mmol) in 10 ml of dry
acetonitrile; upon cooling, the resulting precipitate was filtered,
washed and dried, giving the solid product in 30% yield (Calc.
for C H F N Cu : C, 29.87; H, 0.63. Found: C, 30.67; H,
224 °C (Calc. for C H F O : C, 60.02; H, 1.44. Found: C,
14 4 4
2
60.31; H, 1.21%); d (300 MHz, CDCl ) 7.80 (2H, dd, J 5.6
H
3
and 3.3, ArH), 8.31 (2H, dd,
J
5.6 and 3.3, ArH);
n
(KBr)/cm−1 3450, 1680 (CNO), 1620, 1510, 1470, 1400,
max
16 4 4
4
5
1370.
1.04%); n (KBr)/cm−1 2177 (CN), 1568, 1505, 1389, 1266.
max
5,6,7,8-Tetrafluoro-4,9-dihydronaphtho[2,3-b]thiophene-4,9-
dione 10
Financial support by the European Commission (Project
CT93-0066) is gratefully acknowledged.
This compound was obtained according to the reported pro-
References
cedure.23 To a solution of 6 (0.5 g, 1.64 mmol) and PCl
5
(0.512 g, 2.46 mmol) in 20 ml of dry nitrobenzene, AlCl (0.33 g,
3
1
2
3
M. R. Bryce and L. C. Murphy, Nature, 1984, 309, 119; S. Hunig,
¨
2.46 mmol) was added. The mixture was kept at room tempera-
Pure Appl. Chem., 1990, 62, 395; S. Hunig and P. Erk, Adv. Mater.,
¨
ture for 1 h, and then at 140°C for 4 h. The solvent was
distilled under vacuum and a black oil was obtained. The
crude compound was purified by column chromatography
over silica gel using hexane–ethyl acetate (451) as eluent.
Further purification was accomplished by recrystallization
from ethanol. Yield 55%, mp 190 °C (Calc. for C H F O S:
1991, 225; S. Hunig, J. Mater. Chem., 1995, 5, 1469.
¨
See for example: Proceedings of the International Conference on
Science and T echnology of Synthetic Metals, Tu¨bingen, 1990, Synth.
Met., 1991, 41; Goteborg, 1992, Synth. Met., 1993, 55.
S. Yamaguchi, H. Tatemitsu, Y. Sakata and S. Misumi, Chem. L ett.,
1983, 1229; A. Aumu¨ller and S. Hu¨nig, L iebigs Ann. Chem., 1984,
618; B. Ong and S. Keoshkerian, J. Org. Chem., 1984, 49, 5002;
12 2 4
2
C, 50.36; H, 0.70. Found: C, 50.14; H, 0.77%); d (300 MHz,
A. M. Kini, D. O. Cowan, F. Gerson and R. Mockel, J. Am. Chem.
¨
H
CDCl ) 7.69 (1H, d, J 5.1, thiophene), 7.79 (1H, d, J 5.1,
Soc., 1985, 107, 556.
3
4
5
A. Aumuller and S. Hunig, L iebigs Ann. Chem., 1986, 142.
¨
¨
thiophene); n (KBr)/cm−1 1680 (CNO), 1630, 1540, 1510,
max
(a) P. Cruz, N. Martın, F. Miguel, C. Seoane, A. Albert, F. H. Cano,
´
1480, 1410, 1380.
A. Leverenz and M. Hanack, Synth. Met., 1992, 48, 59; (b) P. Cruz,
N. Martın, F. Miguel, C. Seoane, A. Albert, F. H. Cano,
´
Condensation reaction of quinones 7 and 10 with BTC
A. Gonzalez and J. M. Pingarron, J. Org. Chem., 1992, 57, 6192.
´
´
6
7
N. Martın, J. L. Segura, C. Seoane, C. Torıo, A. Gonzalez and
´
´
´
General procedure. To a solution of the corresponding
J. M. Pingarron, Synth. Met., 1994, 64, 83. See also refs. 2 and 3.
´
quinone (2 mmol) in dry CH Cl (50 ml) at room temperature
A. Aumu¨ller and S. Hu¨nig, Angew. Chem., Int. Ed. Engl., 1984, 23,
447; A. Aumu¨ller, P. Erk, G. Klebe, S. Hu¨nig, U. Schu¨tz and H-
P. Werner, Angew. Chem., Int. Ed. Engl., 1986, 25, 740.
2
2
and under argon atmosphere, TiCl followed by BTC were
4
added dropwise with a syringe by using a variable stoichio-
8
A. Acosta, P. de la Cruz, P. de Miguel, E. Diez-Barra, A. de la Hoz,
F. Langa, A. Loupy, M. Majdoub, N. Mart´ın, C. Sa´nchez and
C. Seoane, Tetrahedron L ett., 1995, 36, 2165.
metric ratio (see below). The reaction was stirred for the
required time and monitored by thin layer chromatography
(TLC) until the starting quinone had been consumed, when
CH Cl (200 ml) was added and the reaction mixture was
9
E. Barranco, N. Martın, J. L. Segura, C. Seoane, P. Cruz, F. Langa,
´
A. Gonzalez and J. M. Pingarron, T etrahedron, 1993, 49, 4881.
´
´
2
2
poured into ice–water (200 g). The reaction was vigorously
stirred until the solution reached room temperature. The
organic phase was separated and washed with water
10 B. S. Jense and V. D. Parker, J. Am. Chem. Soc., 1975, 97, 5211.
11 K. Kobayashi, C. L. Gajurel, K. Umemoto, Y. Mazaki, Bull. Chem.
Soc. Jpn., 1992, 65, 2168; F. Iwasaki, N. Toyota, M. Hirota,
N. Yamazaki, M. Yasui and K. Kobayashi, Bull. Chem. Soc. Jpn.,
1992, 65, 2173.
(3×50 ml), dried (MgSO ) and concentrated to 10 ml. The
4
same volume of hexane (10 ml) was added and the solid
12 U. Shubert, S. Hunig and A. Aumuller, L iebigs Ann. Chem., 1985,
¨
¨
precipitated. It was collected by filtration and washed with
1216.
hexane.
13 R. Gautam Desiraju, Crystal Engineering, Elsevier, Amsterdam,
1989.
14 G. Cascarano, C. Giacovazzo, M. G. Burla, G. Polidori,
M. Camalli, R. Spagna and D. Viterbo, SIR88, 1988.
15 The DIRDIF Program System, P. T. Beurskens, G. Admiraal,
H. Behm, G. Beurskens, W. P. Bosman, S. Garc´ıa-Granda,
R. O. Gould and C. Smykalla, Z. Kristallogr., 1990, suppl. 4, 99.
N,N∞-Dicyano-1,2,3,4-tetrafluoroanthraquinone diimine 8.
Compound 8 was obtained, by stirring for 24 h at room
temperature and refluxing for 3 h using 7 (2.1 mmol), TiCl
4
(8.7 mmol) and BTC (7.4 mmol), in 60% yield; mp 149 °C
(Calc. for C H F N : C, 58.55; H, 1.23. Found: C, 58.34; H,
16 M. Martınez-Ripoll and F. H. Cano, PESOS, A computer pro-
´
16 4 4
4
1.37%); d (300 MHz, CDCl ) 7.93 (2H, dd, J 5.5 and 3.1,
gram for the automatic treatment of weighting schemes, Instituto
Rocasolano C.S.I.C., Serrano 119, 28006, Madrid, Spain.
17 International Tables for X-Ray Crystallography, Birmingham
Press. Birmingham, 1974, vol. IV.
H
3
ArH), 8.67 (2H, br s, ArH); n (KBr)/cm−1 2190 (CN), 1580,
max
1510, 1480, 1410, 1390.
18 S. R. Hall and J. M. Stewart, 1990 XTAL System, University of
Western Australia, Perth, Australia.
N,N∞-Dicyano-5,6,7,8-tetrafluoro-4,9-dihydronaphtho[2,3-
b]thiophene-4,9-diimine 11. Compound 11 was obtained, by
stirring for 24 h at room temperature using 10 (0.17 mmol),
19 J. M. Stewart, F. A. Kundell and J. C. Baldwin, The X-ray 76
Computer Science Center, Univ. of Maryland, College Park,
Maryland, EEUU.
TiCl (1.05 mmol) and BTC (1.19 mmol), in 90% yield; mp
4
20 J. Fayos and M. Mart´ınez-Ripoll, HSEARCH, A computer pro-
gram for the geometric calculations of H atom Coordinates,
Instituto Rocasolano, CSIC, Serrano 119, 28006, Madrid, Spain,
1978.
194 °C (Calc. for C H F N S: C, 50.31; H, 0.60. Found: C,
14 4 4
4
50.14; H, 0.77%); d (300 MHz, CDCl ) 8.09 (1H, d, J 5.2,
H
3
thiophene), 8.80 (1H, d, J 5.2, thiophene); n (KBr)/cm−1
max
2190 (CN), 1580, 1510, 1400, 1300, 1270.
21 M. Nardeli, PARST, Comput. Chem., 1983, 7, 95.
22 Friedel–Crafts and Related Reactions, ed. G. A. Olah, New York,
1964.
Copper salt of compound 8
23 R. Goncalves and E. V. Brown, J. Org. Chem., 1952, 17, 698.
¸
A boiling solution of N,N∞-dicyano-1,2,3,4-tetrafluoroanthra-
quinone diimine 8 (200 mg, 0.6 mmol) in 20 ml of dry aceto-
Paper 6/01628F; Received 7th March, 1996
J. Mater. Chem., 1997, 7(1), 25–29
29