New semiconducting benzo-TTF salts: Synthesis and physical properties

Article abstract of DOI:10.1055/s-2005-865323

The synthesis of new π-electron donors of benzotetrathiafulvalene derivatives 4-11 with one or two hydroxyl functions and additional sulfur or selenium atoms is described. Their redox potentials were measured by cyclic voltammetry. Radical cation salts (RCS) and charge-transfer complexes (CTC) were prepared and their conductivities were measured. Some of the RCS are semi-conductors. Georg Thieme Verlag Stuttgart.

Full text of DOI:10.1055/s-2005-865323

PAPER
1291
New Semiconducting Benzo-TTF Salts: Synthesis and Physical Properties
S
ynthesis of
Ne
o
w Semicond
u
ucting
B
enz
o
i
-TTF
S
z
alts a Boudiba,a Lakhemici Kaboub,a Abdelkrim Gouasmia,*a Jean M. Fabreb
a
Laboratoire des Matériaux Organiques et Hétérochimie, Centre Universitaire de Tébessa,, 12000 Tébessa, Algeria
Fax +213(37)490268; E-mail: akgouasmia@hotmail.com; E-mail: akgouasmia@univ-tebessa.dz
Hétérochimie et Matériaux Organiques, ENSCM, UMR – 5076, 8, rue de l’école normale 34296 Montpellier, France
b
Received 4 August 2004; revised 20 December 2004
Abstract: The synthesis of new p-electron donors of benzotetra-
thiafulvalene derivatives 4–11 with one or two hydroxyl functions
and additional sulfur or selenium atoms is described. Their redox
potentials were measured by cyclic voltammetry. Radical cation
salts (RCS) and charge-transfer complexes (CTC) were prepared
and their conductivities were measured. Some of the RCS are semi-
conductors.
Figure 2 Substituted TTFs 10 and 11
Key words: 1,3-dithiol-2-thio(oxo) benzotetrathiafulvalene,
deprotection, oxidation potential, conductivity
diene-1,4-diyl)-4¢-methylseleno-5¢-(2-hydroxyethylsele-
no)tetrathiafulvalene (11) (Figure 2).
Several strategies towards the selective synthesis of un-
symmetrical benzo-TTFs have been investigated by a
number of groups.8,9 However, the most general route ap-
pears to be that reported in the literature,10,11 which in-
volves the coupling reaction utilizing trialkyl phosphite as
the key step. The synthetic route to benzo-TTFs 4 and 5 is
outlined in Scheme 5. This methodology is based upon the
previous work for the synthesis of 1,3-dithiol analogues
1–3 according to the literature.12–14
The field of organic molecular conductors and supercon-
ductors is in constant evolution. It has been established
that the physical properties of the radical cation salts
(RCS) and charge-transfer complexes (CTC) depend on
the electronic and structural features of TTF derivatives.1,2
From this view point, and within the wider context of ex-
ploiting TTF as a building block in supramolecular chem-
istry,3 much attention has been focused on the generation
of new functionalized tetrathiafulvalene derivatives. To
improve the conducting properties of the synthetic metals,
efforts have been concentrated to enhance the planarity of
the donors, on the one hand by introducing aromatic
groups4 or conjugated systems,5 and on the other hand by
introducing hydrogen bonds.2,6,7 These result in the in-
crease of the dimensionality of the salts formed. On the
basis of these considerations and pursuing our studies on
extended hetero-TTFs, we have focused on the benzo sys-
tem and alcohol group as such potential substituents and
designed 4,5-(buta-1,3-diene-1,4-diyl)-4¢,5¢-bis(2-hy-
droxyethylthio)tetrathiafulvalene (8), 4,5-(buta-1,3-di-
ene-1,4-diyl)-4¢,5¢-bis(2-hydroxyethylseleno)tetrathia-
fulvalene (9) (Figure 1), 4,5-(buta-1,3-diene-1,4-diyl)-4¢-
methylthio-5¢-(2-hydroxyethylthio)tetrathiafulvalene10),
and 4,5-(buta-1,3-diene-1,4-diyl)-4¢-methylseleno-5¢-(2-
hydroxyethylseleno)tetrathiafulvalene (11) (Figure 2).
The key starting material 1 was prepared first in three
steps as shown in Scheme 1. Thus, a solution of anthra-
nilic acid in dioxane was added to a mixture of carbon di-
sulfide, 3-methylnitrobutane and 3-methylbutanol at
reflux to provide 2-(3-methylbutoxy)-1,3-benzodithiol as
an oil. Treatment of this intermediate with tetrafluorobo-
ric acid at 0 °C in diethyl ether led immediately to the for-
mation of the tetrafluoroborate of 1,3-benzodithiolium as
a pink powder in 75% yield. The deprotonation of the re-
sulting salt in refluxing pyridine gave the carbene inter-
mediate, which was reacted with elemental sulfur in
benzene in a small scale. The reaction mixture was ana-
lyzed by mass spectrometry. The formation of the needed
starting reagent 4,5-benzo-1,3-dithiol-2-thione (1) (70%
yield) was observed as a yellow solid, but a second com-
pound, identified as the symmetrical dibenzotetrathiaful-
valene (DBzTTF) was also formed (26% yield)
(Scheme 1). The reaction is not completely specific, be-
cause a second side-reaction takes place by dimerization
of the intermediate carbene.13
4,5-(Buta-1,3-diene-1,4-diyl)-4¢-methylthio-5¢-(2-hy-
droxyethylthio)tetrathiafulvalene (10), and 4,5-(buta-1,3-
The reduction of carbon disulfide by sodium in DMF at
room temperature, followed by reaction of the generated
1,3-dithiol-2-thione-4,5-dithiolate with 0.5 equimolar
amounts of zinc chloride and tetrabutylammonium bro-
mide gave the zinc bis(tetrabutylammonium)-bis(4,5-
Figure 1 Substituted TTFs 8 and 9
dithiolate-1,3-dithiol-2-thione)14
(Scheme 2).
[Zn(dmit)2](Bu4N)2
SYNTHESIS 2005, No. 8, pp 1291–1296
Advanced online publication: 25.04.2005
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x
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x
x
.2
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DOI: 10.1055/s-2005-865323; Art ID: Z15804SS
© Georg Thieme Verlag Stuttgart · New York

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L. Boudiba et al.
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Scheme 4
Reaction of the zincate salts with 3-bromopropionitrile in
refluxing acetonitrile led to the protected thione deriva-
tives. The transchalcogenation was accomplished with
mercuric acetate in chloroform and glacial acetic acid to
yield the starting reagents 2 and 3 in 98% and 96%, re-
spectively (Scheme 4).
Scheme 1
Thus, coupling of the two different half units 4,5-benzo-
1,3-dithiol-2-thione (1) with either 4,5-bis(2¢-cyanoeth-
ylthio)-1,3-dithiol-2-one (2)16 or with 4,5-bis(2¢-cyano-
ethylseleno)-1,3-dithiol-2-one (3)17 using triethyl
phosphite as a base at 100 °C gave the unsymmetrical ben-
zoTTFs 4 and 5 (in 88% and 70% yields, respectively)
(Scheme 5) and three symmetrically self-coupled prod-
ucts.
Scheme 2
An efficient method to prepare stable dianionic alkali met-
al salts of bis(tetrabutylammonium)-bis(4,5-diselenolate-
1,3-dithiol-2-thione) [Zn(dsit)2](Bu4N)2 analogue of dmit
have been reported.15 The 1,3-dithiol-2-thione in THF re-
acts with strong base such as lithium diisopropylamide at
–78 °C, and therefore nucleophilic carbons would be ex-
pected to be capable of reacting with elemental selenium
followed by reaction of the diselenolate with zinc chloride
and tetrabutylammonium bromide (Scheme 3).
Scheme 5
Compounds 4–7 are particularly versatile TTF deriva-
tives, as further functionalization of the thiolate and sele-
nolate anions can be readily achieved by the mono or
double deprotection, followed by addition of electrophile.
Accordingly, TTFs 4 and 5 were reacted with two equiv-
alents of sodium ethoxide in ethanol to remove two cya-
noethyl groups. The resulting dithiolate and selenolate
species was then reacted in situ with 2-chloroethanol to
afford compounds 8 and 9 in 66% and 54% yields, respec-
tively.
TTF-monothiolate and TTF-monoselenolate can be effi-
ciently regenerated (as 1 equiv of cesium salt) by treat-
Scheme 3
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Synthesis of New Semiconducting Benzo-TTF Salts
1293
ment with cesium hydroxide monohydrate in ethanol at compared to dicyanoethyl analogues 4 and 5. It is also
room temperature. This was established by trapping the clear that increasing the number of hydroxy functions as
thiolate and selenate anions with iodomethane, which hydroxyethyl groups as electron-donating substituent on
gave 4,5-benzo-6-methylthio-7-(2¢-cyanoethylthio)TTF
the 4,5-dichalcogeno-1,3-dithiol-2-ylidene ring results in
(6) and 4,5-benzo-6-methylseleno-7-(2¢-cyanoethylsele- a large anodic shift in the oxidation wave. Incorporation
no)TTF (7) in 78 and 91% yields, respectively. The same of a benzene ring instead of cyanoethyl groups may be re-
reaction of thiolate and selenolate anions 6 and 7 with one sponsible for a large higher cathodic shift value of Eox1
,
equivalent of 2-chloroethanol at room temperature pro-
ceeded less efficiently to provide the monohydroxyl func-
tion benzoheteroTTFs 10 and 11 (70% and 60% yields)
(Scheme 6).
E .
ox2, E11/2, E2
1/2
A comparison of the data for compounds 6–11 and
TCEX-TTF (tetracyanoethylchalcogeno)TTF shows that
upon incorporation of a benzene ring instead of cyanoeth-
yl groups may be responsible for a large higher cathodic
shift value of E11/2, E21/2. Moreover, it is observed that
compounds 4–7 exhibit a more important splitting
(DE1/2 = 410–421) than compounds 8–11 (DE1/2 = 359–
414); this could be due to the presence of the cyano groups
inducing a more efficient stabilizing interaction on the
radical cation. The (E21/2–E11/2) can be related to the semi-
quinone formation constant KSEM, which represents the
thermodynamic stability of cation radicals in the SEM
stage by the equation:
Equation 1
KSEM = [SEM]2/[Red][Ox], where KSEM is the equilibrium
constant in equation:
Scheme 6
The electrochemical behavior of the new donors has been
studied by cyclic voltammetry (CV) to measure their oxi-
dation potentials. In each case, the two standard one-elec-
tron reversible oxidation waves were observed and
collected in Table 1. The potentials Eox1, Eox2, E11/2 and
E21/2 of all donors are higher than those of the parent un-
substituted tetrathiafulvalene (TTF) taken as reference.
This implies that the introduction of benzo and chalco-
genoalkyl substituents reduces the electron-donating abil-
ity of the substituted TTFs, because of their high electron-
attracting effect. Nevertheless, by decreasing the number
of cyano substituents or replacing it by a hydroxy group,
which is less electron-attracting than cyano group, the
first oxidation potentials Eox1 decreases for all new com-
pounds (6–11). In the same context, all the new mono and
dihydroxy functionalized TTF compounds (10, 11 and 8,
9, respectively) show a cathodic shift relative to their par-
ent 4,5-benzo-4¢,5¢-dicyanoethylheteroTTF. A compari-
son between the E11/2 data between 4 and 8 and between 5
and 9 reveals that there is a large cathodic shift of the oxi-
dation potentials by 61–82 mV with decreasing strength
of electron-attracting substituents.
Equation 2
In Table 1, the KSEM values of 4–11 are also included. The
values for TTFs are in the order of 106–107, while 8, 9 and
10 have smaller values. Therefore, the thermodynamic
stabilities of cation radicals diminishes in the order 5 =
7 > 11 > 4 = 6 > 9 = 10 > 8, due to a decrease in intramo-
lecular coulombic repulsions. The TCNQ complex forma-
tion was obtained by mixing hot acetonitrile solutions of
the donor and TCNQ in equimolar amounts.20,21 The do-
nor 4 gave orange platelets, compounds 6, 8–11 gave
black powders, while compounds 5 and 7 gave fine black
crystals.
The electrical conductivities of 5-TCNQ, (7–11)-TCNQ,
DBzTTF-TCNQ, were measured by the two-probe meth-
od on single crystals or powder compressed pellets.22
Table 2 shows the room temperature electrical conductiv-
ities (sRT, S/cm), activation energies (Ea, eV) and the ni-
trile stretching absorption bands (nC≡N, cm–1) in the IR
spectra of the TCNQ complexes.
The presence of the methyl substituents in compounds 6
and 7 shifts the oxidation potential Eox1 by ca. 49 mV
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L. Boudiba et al.
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Table 1 Oxidation Potentials (mV) of Ponors 4–11a
Donor
Eox1
778
730
708
718
760
710
688
676
414
724
838
750
638
610
Eox2
1192
1140
1096
1078
1184
1138
1100
1062
840
DEox
414
410
388
360
424
428
412
386
426
436
334
368
346
380
E1
E2
DE1/2
410
410
386
359
421
421
414
386
432
435
335
370
341
385
K = 10(–DE1/2)/0.059
1/2
1/2
4
742
692
666
681
722
673
648
640
375
679
799
700
601
572
1152
1102
1052
1040
1143
1094
1062
1026
807
08.9 × 106
6
08.9 × 106
10
3.4 × 106
8
1.2 × 106
5
1.3 × 107
7
1.3 × 107
11
1.0 × 107
9
3.5 × 106
TTF
–
–
–
–
–
–
DBz-TTF
TCET-TTF
TCES-TTF
TMT-TTF
TMS-TTF
1160
1172
1118
984
1114
1134
1070
942
990
957
a All oxidation potentials are determined in CH2Cl2 containing Bu4NPF6 (0.1 M) with SCE as the reference electrode and platinum as working
and counter electrodes.
DBz: dibenzo, TCET: tetracyanoethylthio, TCES: tetracyanoethylseleno, TMT: tetramethylthio, TMS: tetramethylseleno.
Table 2 Electrical Conductivity (s), Activation Energies (Ea), Nitrile Stretching Absorption Bands (nC≡N)a and Degree of Charge Transfer
(r) of CTC
Complexes
4-TCNQ
5-TCNQ
10-TCNQ
11-TCNQ
6-TCNQ
7-TCNQ
8-TCNQ
9-TCNQ
DBzTTF-
TCNQ
s (S/cm)
Ea (eV)
6.2 × 10–6
0.41
3.2 × 10–6
0.42
1.5 × 10–5
0.40
1.0 × 10–5
0.42
2.1 × 10–6
0.42
3.9 × 10–6
0.42
1.5 × 10–5
0.41
1.2 × 10–5
0.39
2.0 × 10–4
–
E11/2 (mV)
742
722
666
648
692
673
681
640
610
–
n
C≡N (cm–1)
r (e–/mol)
2216.2
0.25
2213.1
0.32
2203.8
0.53
2200.0
0.62
2211.0
0.37
2209.4
0.41
2204.8
0.50
2200.2
0.61
–
a Values of the nC≡N (cm–1) for neutral TCNQ (2227) and for the donors 4 (2249.8), 5 (2245.9), 6 (2245.9), 7 (2244).
The complexes with alcohol donors 8–11 show a semi- studied first. The formation of these salts were carried out
conducting behavior and the values of electrical conduc- by galvanostatic electrocrystallization with the appropri-
tivities were 1/13 of the DBzTTF-TCNQ complex ate anion under constant current (5 mA) in anhydrous
measured under the same conditions. The other TCNQ THF.23 The donors 8–11 provided black needles and black
complexes exhibited comparatively low electric conduc- powders. On the other hand, no formation of radical cat-
tivities (= 10–6 S/cm).
When a comparison was made between the E11/2 values of
the donors and nC≡N values of the TCNQ complexes, it
ion salts was observed in the reaction of 10 and 11 with ni-
trate, chlorine and perchlorate anions. Also, no reaction of
9–11 with bromine and iodine anions was observed.
was found that the nC≡N shifts to lower wave number with Now, various counter-anions were next used for salt for-
a decrease in the E11/2 values. This means that the degree mation with the new donors. The electrical conductivities
of electron transfer from the donor to TCNQ increases in of the RCS are shown in Table 3. The (10)2-Br, (11)2-Br,
the TCNQ complex, as the E1 value of the donor be- (8)2-Cl and (9)2-Cl showed increased electrical conductiv-
1/2
comes smaller.
ities around 103–104 S/cm as compared to the correspond-
ing TCNQ complexes.
The formation of radical cation salts (RCS) of the new
4¢,5¢-dichalcogeno donor systems with various anions was
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Synthesis of New Semiconducting Benzo-TTF Salts
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Table 3 Electrical Conductivities (S/cm) and [Activation Energies (eV)] of the RCS
–
–
–
–
TTF
Br–
NO3
10–5
Cl–
ClO4
Br3
I3
8
8.9 × 10–6
[0.39]
9.2 × 10–3
[0.25]
1.9 × 10–5
[0.36]
4.7 × 10–6
[0.42]
1.2 × 10–5
[0.38]
[0.38]
9
10
11
2.7 × 10–6
1.5 × 10–5
9.3 × 10–3
6.5 × 10–5
–
–
–
–
–
–
[0.41]
[0.39]
[0.28]
[0.33]
2.4 × 10–2
[0.18]
–
–
–
–
–
–
5.0 × 10–2
[0.16]
13C NMR (CDCl3): d = 18.91 (CH2CN), 31.30 (CH2S), 118.2 (CN).
MS (FAB+): m/z = 424 [M]+.
For the RCS mentioned above, with comparatively higher
electric conductivities, the Ea values were small (0.16–
0.28 eV). On the other hand, the semiconducting and in-
sulating salts such as (8)2-NO3, (9)2-NO3, (8)2-ClO4, (9)2-
ClO4, (8)2-I3, (8)2-Br, (9)2-Br and (8)2-Br3 have consider-
ably higher activation energies (0.33–0.42 eV). These re-
sults are consistent with those of the IR spectra of the salts
Anal. Calcd for C16H12N2S6: C, 45.28; H, 2.83. Found: C, 45.35; H,
3.03.
5
Yellow needles; yield: 70%; mp 125 °C.
in KBr pellets. Thus, the highly conducting salts (10)2-Br 1H NMR (CDCl3): d = 2.86 (t, 4 H, CH2CN, J = 7.0 Hz), 3.08 (t, 4
H, CH2Se, J = 7.0 Hz), 7.23 (m, 4 Harom).
and (11)2-Br (0.025 and 0.05 S/cm respectively), revealed
a broad absorption at the wavenumber of 2850 cm–1,
which can be assigned as a mixed-valence transition.
13C NMR (CDCl3): d = 19.26 (CH2CN), 23.43 (CH2Se), 118.2
(CN).
MS (FAB+): m/z = 518 [M]+.
In summary, new TTF 4–11 containing benzo, heteroeth-
ylcyano, heteromethyl and heterohydroxyethyl substitu-
ents have been synthesized. Cyclic voltammetry showed
two reversible single-electron oxidation waves. The new
donors readily formed charge-transfer complexes with
electron acceptor TCNQ and several radical cation salts
with various anions. Electrical conductivity of thirteen
complexes showed semi-conducting behavior and appear
sufficiently promising to continue work in this area. Fur-
ther studies on the electronic properties and structure de-
termination of these salts are currently under investigation
and wile be published separately.
Anal. Calcd for C16H12N2S4Se2: C, 37.06; H, 2.31. Found: C, 37.37;
H, 2.48.
4,5-Bis(2¢-hydroxyethylthio)-6,7-benzoTTF(DHET-BzTTF)(8)
and 4,5-Bis(2¢-hydroxyethylseleno)-6,7-benzoTTF (DHES-
BzTTF) (9)
These compounds were prepared by adaptation of a procedure de-
scribed in the literature.10,12
8
Orange-yellow powder; yield: 66%; mp 128 °C.
1H NMR (CDCl3): d = 2.92 (s, 2 H, OH), 3.01 (m, 4 H, CH2S,
J = 5.6 Hz), 3.75 (t, 4 H, CH2O, J = 5.6 Hz), 7.20 (m, 4 Harom).
13C NMR (CDCl3): d = 39.38 (CH2S), 59.86 (CH2O).
MS (FAB+): m/z = 406 [M]+.
NMR spectra were recorded on a Bruker AC 200 instrument. FAB
mass spectra were recorded on a JEOL JMS-DX 300 spectrometer.
IR spectra were recorded on a Equinox 55 (resolution 0.5 cm–1).
Melting points were measured on a Büchi apparatus. Cyclic volt-
ammetry measurements were carried out on a PAR-273 poten-
tiostat/galvanostat.
Anal. Calcd for C14H14O2S6: C, 41.37; H, 3.44. Found: C, 41.38; H,
3.50.
9
Yellow needles; yield: 54%; mp 134 °C.
1H NMR (CDCl3): d = 2.74 (s, 2 H, OH), 3.07 (m, 4 H, CH2Se,
J = 5.6 Hz), 3.81 (t, 4 H, CH2O, J = 5.6 Hz), 7.20 (m, 4 Harom).
4,5-Bis(2¢-cyanoethylthio)-6,7-benzoTTF (DCET-BzTTF) (4)
and 4,5-Bis(2¢-cyanoethylseleno)-6,7-benzoTTF (DCES-
BzTTF) (5)
13C NMR (CDCl3): d = 23.50 (CH2Se), 59.98 (CH2O).
MS (FAB+): m/z = 500 [M]+.
Each 4,5-bis(2¢-cyanoethylthio)-1,3-dithiol-2-one (2; 0.31 g, 1.08
mmol) or 4,5-bis(2¢-cyanoethylseleno)-1,3-dithiol-2-one (3; 0.41 g,
1.08 mmol) or 4,5-benzo-1,3-dithiol-2-thione (1; 0.2 g, 1.08 mmol)
was suspended in freshly distilled triethyl phosphite (10 mL) under
N2 and heated with stirring at 100 °C for 90 min. Then, the mixture
was cooled to 0 °C and the precipitate was collected by filtration.
The product was washed with cold MeOH (3 × 10 mL), dried in
vacuo and chromatographed (silica gel, CH2Cl2).
Anal. Calcd for C14H14O2S4Se2: C, 33.60; H, 2.80. Found: C, 33.72;
H, 2.90.
4-(2¢-Cyanoethylthio)-5-methylthio-6,7-benzoTTF (CETMT-
BzTTF) (6) and 4-(2¢-Cyanoethylseleno)-5-methylseleno-6,7-
dimethylthioTTF (CESMS-BzTTF) (7)
4
These compounds were prepared by adaptation of a procedure de-
Orange-yellow powder; yield: 88%; mp 145 °C.
scribed in the literature.16,17
1H NMR (CDCl3): d = 2.74 (t, 4 H, CH2CN, J = 7.0 Hz), 3.09 (t, 4
H, CH2S, J = 7.0 Hz), 7.20 (m, 4 Harom).
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1296
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L. Boudiba et al.
PAPER
Charge Transfer Complexes (CTC)
Orange solid; yield: 78%; mp 126 °C.
1H NMR (CDCl3): d = 2.48 (s, 3 H, SCH3), 2.70 (t, 2 H, CH2CN,
J = 7.0 Hz), 3.03 (t, 2 H, CH2S, J = 7.0 Hz), 7.20 (m, 4 Harom).
13C NMR (CDCl3): d = 18.74 (SCH3), 19.20 (CH2CN), 31.21
(CH2S), 118.2 (CN).
The charge transfer complexes were isolated by a chemical redox
reaction between a donor (4–11) and TCNQ as the electron accep-
tor. In each experiment, equimolar amounts (0.1 mmol) of the donor
and TCNQ were separately dissolved in boiling MeCN and then
mixed.
MS (FAB+): m/z = 385 [M]+.
Acknowledgment
Anal. Calcd for C14H11NS6: C, 43.63; H, 2.85. Found: C, 43.55; H,
2.78.
This work was carried out in the framework of a ‘Franco-Algerian
Inter-University Cooperation Programme’ with the support of the
CMEP, the Algerian ministry of higher education and the French
Ministry of the foreign affairs whom we thank warmly.
7
Orange powder; yield: 91%; mp 124 °C.
1H NMR (CDCl3): d = 2.40 (s, 3 H, SeCH3), 2.86 (t, 2 H, CH2CN,
J = 7.0 Hz), 3.03 (t, 2 H, CH2Se, J = 7.0 Hz), 7.21 (m, 4 Harom).
13C NMR (CDCl3): d = 9.90 (SeCH3), 19.45 (CH2CN), 23.21
(CH2Se), 118.2 (CN).
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H, 2.48.
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(6) Ozturk, T.; Rice, C. R.; Wallis, T. D. J. Mater. Chem. 1995,
5, 1553.
(7) Marshallsay, G. J.; Bryce, M. R.; Cooke, G.; Jorgensen, T.;
Becher, J.; Reynolds, C. D.; Wood, S. Tetrahedron 1993, 49,
6849.
(8) Morand, J. P.; Brzezinski, L.; Manigand, C. J. Chem. Soc.,
Chem. Commun. 1986, 1050.
(9) Moses, P. R.; Chambers, J. Q.; Sutherland, J. O.; Williams,
D. R. J. Electrochem. Soc. 1975, 122, 608.
(10) Kreif, A. Tetrahedron 1986, 42, 1209.
(11) Narita, M.; Pittman, C. U. Synthesis 1976, 489.
(12) Nakayama, J.; Suguira, H.; Hoshino, M. Tetrahedron Lett.
1983, 24, 2585.
(13) Fabre, J. M.; Giral, L.; Gouasmia, A. K.; Cristau, H. J.;
Ribeill, Y. Bull. Soc. Chim. Fr. 1987, 823.
4-(2¢-Hydroxyethylthio)-5-methylthio-6,7-benzoTTF
(HETMT-BzTTF) (10) and 4-(2¢-Hydroxyethylseleno)-5-meth-
ylseleno-6,7-benzoTTF (HESMS-BzTTF) (11)
These compounds were prepared by adaptation of a procedure de-
scribed in the literature.17
10
Orange-yellow powder; yield: 70%; mp 105 °C.
1H NMR (CDCl3): d = 2.44 (s, 1 H, OH), 2.47 (s, 3 H, SCH3), 2.94
(t, 2 H, CH2S, J = 5.6 Hz), 3.72 (t, 2 H, CH2O, J = 5.6 Hz), 7.20 (m,
4 Harom).
13C NMR (CDCl3): d = 19.40 (SCH3), 39.19 (CH2S), 59.94 (CH2O).
MS (FAB+): m/z = 376 [M]+.
Anal. Calcd for C13H12OS6: C, 41.48; H, 3.19. Found: C, 41.60; H,
3.04.
(14) Steimecke, G.; Sieler, H. J.; Kirmse, R.; Hoyer, E.
Phosphorus, Sulfur Relat. Elem. 1979, 7, 49.
(15) Papzvassiliou, G. C.; Kakoussis, V. C.; Zambounis, J. S.;
Mousdis, G. A. Chem. Scr. 1989, 29, 123.
(16) Binet, L.; Fabre, J. M.; Montginoul, C.; Simonsen, K. B.;
Becker, J. J. Chem. Soc., Perkin Trans. 1 1996, 783.
(17) Gouasmia, A. K.; Fabre, J. M.; Boudiba, L.; Kaboub, L.;
Carcel, C. Synth. Met. 2001, 120, 809.
11
Orange solid; yield: 60%; mp 93 °C.
1H NMR (CDCl3): d = 2.39 (s, 1 H, OH), 2.42 (s, 3 H, SeCH3), 3.08
(m, 2 H, CH2Se, J = 5.6 Hz), 3.89 (t, 2 H, CH2O, J = 5.6 Hz), 7.24
(m, 4 Harom).
13C NMR (CDCl3): d = 9.90 (SeCH3), 23.21 (CH2Se), 60.00
(CH2O).
(18) Deuchert, K.; Hünig, S. Angew. Chem., Int. Ed. Engl. 1978,
17, 875.
MS (FAB+): m/z = 470 [M]+.
(19) Hünig, S.; Berneth, H. Top. Curr. Chem. 1980, 92, 1.
(20) Williams, J. M.; Ferraro, J. R.; Thorn, R. I.; Carlson, K. D.;
Geiser, U.; Wang, H. H.; Kini, A. M.; Wangbo, M. H. In
Organic Superconductor (Including Fullerenes), Synthesis,
Structure, Properties and Theory; Prentice-Hall: Engelwood
Cliffs, 1992, and references cited therein.
(21) Bryce, M. R. J. Mater. Chem. 1995, 5, 1481.
(22) Coleman, L. B. Rev. Sci. Instrum. 1975, 46, 1125.
(23) Bechgaard, K.; Carneiro, K.; Rasmussen, F. B.; Olsen, M. J.
Am. Chem. Soc. 1981, 103, 2440.
Anal. Calcd for C13H12OS4Se2: C, 33.19; H, 2.55. Found: C, 33.30;
H, 2.46.
Electrocrystallization
The radical cation salts were prepared by galvanostatic electro-
chemical oxidation on a platinum electrode at a constant current (5
mA) in a 15 mL H-type cell from a solution of an appropriate tet-
rabutylammonium salt as an electrolyte (Bu4NX, 0.5 M, typically in
THF) containing the donor 8, 9, 10 or11 (10–3 M).
Synthesis 2005, No. 8, 1291–1296 © Thieme Stuttgart · New York