Syntheses, structure and conducting properties of halogenated ethylenedioxytetrathiafulvalenes

Article abstract of DOI:10.3987/COM-00-S(I)79

4,5-Diiodo-, 4,5-dibromo-, and 4,5-dichloro-4′,5′-ethylenedioxytetrathiafulvalenes (EDO-TTFI₂, EDO-TTFBr₂, and EDO-TTFCl₂) were synthesized in moderate to good yields by the two routes. The first route contains the reaction of EDO-TTF with LDA, followed by quenching with halogenated reagents, and the second route consists of the P(OR)₃-mediated cross-coupling of 4,5-dihalogenated 1,3-dithiole-2-ones with 4,5-ethylenedioxy-1,3-dithiole-2-thione. The structures of EDO-TTFI₂ and EDO-TTFCl₂ were determined by X-Ray analysis. The radical-cation salts derived from EDO-TTFI₂, EDO-TTFBr₂, and EDO-TTFCl₂ show high conductivities, although these compounds contain electron-withdrawing halogens as the substituent.

Full text of DOI:10.3987/COM-00-S(I)79

HETEROCYCLES, Vol. 54, No. 2, pp. 833-848, Receivrd, 19th June, 2000
SYNTHESES, STRUCTURE AND CONDUCTING PROPERTIES OF
1
HALOGENATED ETHYLENEDIOXYTETRATHIAFULVALENES
Masahiko Iyoda,* Yoshiyuki Kuwatani, Eiji Ogura, Kenji Hara, Hironori Suzuki,
Takahiro Takano, Koji Takeda, Jun-ichi Takano, Kohei Ugawa, Masato Yoshida,
†
Haruo Matsuyama, Hiroyuki Nishikawa, Isao Ikemoto, Takehiro Kato, Naoki
†
†
†
†
Yoneyama, Jun-ichi Nishijo, Akira Miyazaki, and Toshiaki Enoki
Department of Chemistry, Graduate School of Science,
Tokyo Metropolitan University, Hachioji, Tokyo 192-0397, Japan
†
Department of Chemistry, Graduate School of Science and Technology,
Tokyo Institute of Technology, O-okayama, Tokyo 152-8551, Japan
Abstract- 4,5-Diiodo-, 4,5-dibromo-, and 4,5-dichloro-4' ,5' -ethylenedioxytetra-
thiafulvalenes (EDO-TTFI , EDO-TTFBr , and EDO-TTFCl ) were synthesized in
2
2
2
moderate to good yields by the two routes. The first route contains the reaction of
EDO-TTF with LDA, followed by quenching with halogenated reagents, and the
second route consists of the P(OR) -mediated cross-coupling of 4,5-dihalogenated
3
1,3-dithiole-2-ones with 4,5-ethylenedioxy-1,3-dithiole-2-thione. The structures
of EDO-TTFI and EDO-TTFCl were determined by X-Ray analysis. The
2
2
radical-cation salts derived from EDO-TTFI , EDO-TTFBr , and EDO-TTFCl
2
2
2
show high conductivities, although these compounds contain electron-withdrawing
halogens as the substituent.
INTRODUCTION
2
Highly polarizable electron donors have attracted current attention, because weak interactions between
polarizable substituents may lead to the formation of molecular networks with stacking columns in line with
3
the crystal engineering, and because intermolecular interactions between radical-cations in the complexes
4, 5
can be enhanced by electrostatic interaction to increase dimensionality of the molecular conductors.
6, 7
Among them, the substitution of halogen atoms on the TTF framework has been extensively studied,
although the electronegativity of halogens decreases the donor properties, thus causing difficulty in forming
molecular conductors. Previously, we reported the synthesis and unique conductivities of CT-complexes
and radical salts of halogenated ethylenedithiotetrathiafulvalenes (EDT-TTFX ' s) and disclosed an
2
8
interesting behavior of halogen-substituents in the crystals.
Our continuing interests in the weak
interaction between halogens and chalcogens in crystals prompted us to investigate the halogenated

derivatives of EDO-TTF (1 ). We report here the synthesis of EDO-TTFI (2), EDO-TTFBr (3), and
2
2
EDO-TTFCl (4) and the properties of their CT-complexes and radical salts, together with the X-Ray
2
1
structures of 2-4 and their radical-cation salts.
I
I
Br
Br
O
O
Cl
Cl
O
O
O
O
S
S
S
S
S
S
S
S
O
O
S
S
S
S
S
S
S
S
EDO-TTF 1
EDO-TTFI 2
EDO-TTFBr 3
EDO-TTFCl 4
2
2
2
RESULTS AND DISCUSSION
Synthesis of Ethylenedioxytetrathiafulvalene ( 1) .
9
EDO-TTF (1) was first synthesized in 1990, but the total yield of 1 appeared not to be high enough to
9,10
produce a gram-scale of 1.
Therefore, we first improved the synthetic procedure of 1 (Scheme 1). The
O
O
Cl
Cl
O
SCSNMe
O
SCSNMe
2
2
2
NaSCSNMe
Toluene, reflux
15 h
2
Br
2
DMF, 70 °C, 4 h
CH Cl2, 0 °C
2
O
SCSNMe
O
6
5
7
+
+
Br
O
S
O
O
O
O
S
S
15 Torr
NaSH
-
-
NMe
NMe
Br
S
Br
2
2
110 °C, 5 h
EtOH, AcOH
rt, 2 h
S
S
S
O
8
9
10
COOMe
COOMe
S
S
O
COOMe
COOMe
R
11
R
R
O
S
S
S
S
S
S
S
+
S
P(OEt) , 60 °C, 4 h
3
O
R
12
13: R = OCH CH O 14: R = CO Me
2 2 2
COOMe
O
O
O
S
S
S
S
S
S
S
LiBr H O, HMPA
LiBr H O, HMPA
2
2
12
rt to 150 °C
S
rt to 150 °C
O
15
1
Scheme 1
reaction of 1,2-dichlorodioxane (5) with sodium dimethyldithiocarbamate in DMF at 70 °C for 4 h afforded
10,11a
the bis(dithiocarbamate) (6) in 74% yield.
Treatment of 6 in refluxing toluene for 15 h formed 7 in
95% yield. A similar reaction of 6 in DMSO yielded a mixture of products containing 7. Bromination of 7
in CH Cl at 0 °C produced the bromide (8) in quantitative yield, and dehydrobromination of 8 under
2
2

10, 11b
reduced pressure at 110 °C afforded 9 in almost quantitative yield.
The reaction of 9 with sodium
11b,12
hydrogensulfide in ethanol-acetic acid at room temperature formed the thione (10) in 73% yield.
The
cross-coupling reaction of 10 with 11 in P(OEt) at 60 °C for 4 h produced the diester (12) in 77% yield,
3
9b,13
together with small amounts of 13 and 14.
The decarboxylation of 12 with lithium bromide
monohydrate in HMPA at room temperature to 150 °C afforded EDO-TTF (1) in 70% yield, together with
the monoester (15) (20%). The monoester (15) can be converted into 1 in 50% yield under the similar
decarbonylation conditions. Thus, 1 can be synthesized in 40% overall yield starting from 5.
Synthesis of Halogenated Ethylenedioxytetrathiafulvalenes (2-4).
6,7
Halogenated tetrathiafulvalene and its derivatives have attracted considerable attention in recent years,
because of the unique crystal structures and electric conductivities of their CT-complexes and radical
14
15
salts, and because of the synthetic utilities as a building block for extended TTF systems.
The
syntheses of 2, 3, and 4 were attempted using the two synthetic routes shown in Scheme 2. The first route
is based on the lithiation-halogenation sequence (eq. 1). Since TTF monoanions can be easily prepared
from TTF and its derivatives with butyllithium or LDA and can be transformed into halogenated derivatives
6,7
by treatment with alkyl halides or tosyl halides,
1 can be converted into the corresponding anion which is
halogenated to produce EDO-TTFX (16). The second route is a cross-coupling reaction of the thione (10)
2
with dihalogenated 1,3-dithiole-2-one (17) using trialkyl phosphite (eq. 2). The combination of 10 with
electron-donating group and 17 with electron-withdrawing group may be necessary to produce the cross-
coupling product 1 6 in good yield.
X
X
O
O
O
O
S
S
S
S
S
S
S
S
1) base (2 equiv.)
2) Halogenation
(1)
(2)
1
EDO-TTFX (16)
2
X
X
X
O
O
S
S
S
S
S
S
P(OR)
3
S
+
O
S
S
X
O
O
EDO-TTFX (16)
10
17
2
Scheme 2
At first, we investigated the route 1 (eq. 1). Although the reaction of EDT-TTF with 2 equiv. of LDA
16
produces the vinylthio-thiolate anion via the cleavage of the ethylenedithio ring, EDO-TTF (1) is fairly
stable to a strong base like LDA at low temperature. Thus, the treatment of 1 with 2 equiv. of LDA in THF
at -78 °C, followed by the reaction with 3 equiv. of CF (CF ) I at -78 - 0 °C produced EDO-TTFI (2) in
3
2 5
2
17
55% yield, together with a small amount of monoiodide (18) (Scheme 3).
In a similar manner, EDO-
TTFI (18) was prepared selectively by the successive treatment of 1 with LDA (1 equiv.) in THF at -78 °C
and F ClCCFClI (3 equiv.) at the same temperature. In the case of the bromide (3), the reaction of 1 with
2
LDA (2.15 equiv.) in THF at -78 °C for 40 min, followed by treatment with BrCl CCCl Br (2.25 equiv.)
2
2
at -78 °C to room temperature produced 3 in 74% yield. Similarly, treatment of 1 with LDA (2.05 equiv.)
in THF at -78 °C for 40 min, followed by the reaction with hexachloroethane (2. 75 equiv.) at -78 °C to

room temperature produced 4 in 56% yield. The dibromide (3) and the dichloride (4) were isolated by
column chromatography on silica gel, followed by gell permeation chromatography (GPC) separation.
Interestingly, no monobromide and monochloride were isolated in these reactions.
O
I
S
S
S
S
1) LDA (2 equiv.)
O
O
2) n-C F I (3 equiv.)
S
S
S
S
6 13
O
O
I
I
2
S
S
S
S
1) LDA (1 equiv.)
1
2) F ClCCFClI (3 equiv.)
2
O
18
Br
O
O
S
S
1
S
S
S
S
S
1) LDA (2.05 equiv.)
2) BrCl CCCl Br (2.25 equiv.)
S
S
2
2
Br
Cl
O
O
O
3
4
O
S
S
S
S
1) LDA (2.15 equiv.)
S
2) Cl CCCl (2.75 equiv.)
S
S
3
3
Cl
O
O
1
Scheme 3
Second, we attempted the route 2 (eq. 2). Recently, the synthesis of 4,5-diiodo-1,3-dithiole-2-one (17a)
7b
starting from 19 was reported.
For the cross-coupling reaction of 10 with 17a, P(OMe) was found to
3
be more effective than P(OEt) . Thus, the reaction of 10 and 17a with P(OMe) in refluxing benzene
3
3
afforded 2 in 59% yield, together with 21 (29%) (Scheme 4). 4,5-Dibromo-1,3-dithiole-2-one (17b) was
n
prepared from 19. The reaction of 19 with Bu Li (1.01 equiv.) in THF at -78 °C for 1 h, followed by
treatment with 1,2-dibromotetrachloroethane (2.19 equiv.) formed 20b in 32% yield. Treatment of 20b
with Hg(OAc) in CH Cl -acetic acid at room temperature led to 17b in 95% yield. In a similr manner to
2
2
2
the synthesis of the diiodide (2), the reaction of 10 and 17b with P(OMe) in refluxing benzene afforded 3
3
in 59% yield, together with bisethylenedioxytetrathiafulvalene (13) (4%) and 22 (15%). In the case of
n
17c, however, the reaction of 19 with LDA or Bu Li in THF at -78 °C, followed by treatment with p-
toluenesufonyl chloride or hexachloroethane formed 20c in low yield. Therefore, we could not attempt the
reaction of 10 with 17c. Although the lithiation-halogenation procedure is superior method for the
synthesis of 2-4, the cross-coupling method shown in Scheme 4 serves sometimes alternatively and can
also produce a gram-scale of 2 and 3 without experimental difficulties.
X
X
X
X
n
S
S
S
S
S
Hg(OAc)
1) LDA or Bu Li
2
S
O
S
S
19
2) Ts-X or BrCCl CCl Br
2
2
20
17
a: X = I; b: X = Br; c: X = Cl
X
X
S
X
X
O
O
O
X
S
S
S
S
S
S
P(OMe)
3
+
S
+ O
benzene, ∆
S
X
S
S
S
S
O
X
X
13: X = OCH CH O
21: X = I 22: X =Br
10
17
2
2
2
2: X = I
3: X = Br
Scheme 4

Thus, the structures and conductivities of the radical-cation salts derived from 2 are somewhat different
from those derived from 3. In addition, an appreciable difference was observed in the conducting behavior
-
-
of the radical-cation salts based on 3 and 4. The donor (3) formed the metallic I and AuI salts, whereas
3
2
-
the I salt of 4 was a semiconductor. The 3:1 PF salt of 3 was a semiconductor, but the 2:1 salt of 4 was
3
6
metallic at room temperature with high conductivity. To our knowledge, no metallic radical-cation salt
based on brominated and chlorinated TTF derivatives has been reported to date. Therefore, the metallic
conducting behavior of (3) •I , (3) •AuI and (4) •PF is the first example for the radical-cation salts
3 3
2
2
2
6
derived from brominated and chlorinated TTF derivatives.
Table 2. Electrical conductivities of radical-cation salts derived from 2-4 and 18.
a
-1
Acceptor
D:A
Donor
Solvent
σ /S cm
rt
b
d
d
b
2
2
2
2
TCNQ
152
1.8
68
CHCl3, MeCN
PhCl
1:1
2:1
2:1
3:1
-3
c
I2(I)2
x10
PhCl
TCE
ClO4
PF6
(TMI = 50 K)
200 (Ea = 60 meV / 100 K)
(Ea = 172 meV / 273 K)
7.2
6.3
4.3
9.9
9.6 (Ea = 4.3 meV / 50 K)
(Ea = 17.2 meV / 200 K)
22
3.6x10
169
d
d
d
2
2
18
3
AuI2
Br
DCE
CH2Cl2
CHCl3, MeCN
2:1
2:1
2:1
(TMI = 40 K)
-2
-2
x10
x10
TCNQ
I3
d
3:1
(TMI = 180 K)
DCE
DCE
d
3:1
3
PF6
b
TCE
PhCl
TCE
(TMI = 100 K)
2:1
AuI2
I3
PF6
3
4
4
-2
d
d
1:1
(TMI = 262 K)
2:1
a
b
Room-temperature conductivity measured by a four-probe technique. Determined by
c
n
elemental analysis. Prepared by electrochemical oxidation of 2 in the presence of Bu NI .
d
4
3
Determined by X-Ray analysis.
-
The crystal structure of the unusual radical-cation salt (2) •I (I ) in Table 2 was determined by X-Ray
2 2
2
-
analysis (Figure 3). The crystal packing of (2) •(I )(I ) shows that two donors and four iodines are
2
2
2
stacked along the b axis to form a mixed-stacking structure. The central iodine molecule has a
crystallographic S symmetry, and the packing of the molecules in the crystal show that a pair of EDO-
2
TTFI ' s lies on a crystallographic center of inversion. The distance between the donor best plane and
2
iodine atoms is ca. 3.40 Å, whereas the face-to-face distance between the two donors is ca. 3.51Å. There
are many intermolecular contacts less than the sum of van der Waals radii. Thus, the I(1)•••I(3),
I(2)•••I(3), S(1)•••S(4), S(2)•••S(3), and S(4)•••O(1) distances are 3.4024(8), 3.399(1), 3.4034(9),
3.514(3), 3.517(3), and 2.953(6) Å, respectively, which are much less than the I•••I, S•••S, S•••O van der
Waals distances (I: 2.15 Å; S: 1.85 Å; O: 1.40 Å). Although iodide ions usually form a chain structure
-
-
-
2-
with an odd number of atoms such as I , I , I , etc., the I chain consists of an iodine molecule (I ) and
3
5
4
2
-
2-
two iodides (I ). To our knowledge, this is the first report of the structure of I . In accord with the
4
-
mixed-stacking structure as a 1:1 radical-cation salt, the room temperature conductivity of (2) •(I )(I ) is
2
2
2
-3
-1
1.8 x 10 S cm .

there is no short distance in the DAD unit less than the sum of van der Waals radii, the inter-column I•••N
and S•••S interaction is fairly large. Thus, the I(1)•••N(2) distance (3.09 Å) is 15% shorter than the sum of
van der Waals radii (3.65 Å), and the S(1)•••S(2), S(1)•••S(3), S(3)•••S(3) distances (3.43-3.63 Å) are 2-
7% shorter than the sum of van der Waals radii. In the DAD unit, the degree of the charge transfer in
19
TCNQ part was estimated to be 0.22,
reflecting the C≡N bond length (1.145 and 1.130 Å) in
20
(18) •TCNQ [the C≡N bond length in TCNQ is 1.14 Å, ]. It is worth noting that (18) •TCNQ shows
2
2
-3
-1
conductivity (4.3 x 10 S cm ) at room temperature. Since the CT-complex has a mixed stacked structure
with a staggered packing, the room temperature conductivity of (1 8) •TCNQ is unusually high.
2
Our results reported here disclose that halogenated EDO-TTF derivatives may produce a new type of
synthetic metals using the X•••S, X•••O, and X•••X interactions in the crystals. We believe that the radical-
cation salts derived from 2-4 and 18 will develop a new aspect in the chemistry of molecular conductors
using a new concept based on the crystal engineering.
EXPERIMENTAL
1
13
General Procedure.
H and C NMR spectra were recorded on JEOL JNM-LA-500 and JEOL JNM-
LA-400 instruments. Spectra are reported (in δ) referenced to Me Si. Unless otherwise indicated, CDCl
4
3
was used as solvent. Data are reported as follows: chemical shifts, multiplicity (s = singlet, d = doublet, t =
triplet, m = multiplet, br = broad), integration, and coupling constant (Hz). MS spectra were determined on
a JEOL JMS-AX 500 instrument. Only the more intense or structurally diagnostic mass spectral fragment
ion peaks are reported. Melting points were determined on a Yanaco Micro melting point apparatus MP-
500D and are uncorrected.
Elemental analyses were performed in the microanalysis laboratory of Tokyo
Metropolitan University. Column chromatography was carried out with use of EM Reagents silica gel 60,
70-230 mesh ASTM, Daiso silica gel 1001W, or neutral alumina activity II-III, 70-230 mesh ASTM. Gel
permeation liquid chromatography (GPC) was performed on AL LC-08 and LC-918 liquid chromatography
instruments with JAIGEL-1H column (20 mm x 600 mm x 2) and chloroform as eluent. All solvents were
13
7b
dried by conventional procedures. 1,3-Dithiole-2-thione (19), 4,5-diiodo-1,3-dithiole-2-thione (20a),
7b
and 4,5-diiodo-1,3-dithiole-2-one (17a) were prepared according to the published procedures.
2,3-Dichloro-1,4-dioxane (5).
To 1, 4-dioxane (88.1 g: 84.6 mL, 1.0 mol) was added dropwise SO Cl (269.9 g: 161.6 mL, 2.0 mol) at
2
2
0 °C during 1 h, and then the mixture was stirred at 60 °C for 18 h. The mixture was cooled to rt, and
gaseous nitrogen was bubbled through the mixture for 1 h. The product was purified by distillation under
1
reduced pressure to afford 5 (114.5 g, 72 %) as a colorless liquid (bp 82-83 °C / 18 torr ). H-NMR (400
MHz) δ 5.88 (s, 2H), 4.20-4.22 (m, 2H), 3.57-3.60 (m, 2H).
2,3-Bis(dimethyldithiocarbamyl)-1,4-dioxane (6).
A solution of 5 (38.27 g, 0.244 mol) and sodium dimethyldithiocarbamate (91.56 g, 0.569 mol) in DMF
(500 mL) was heated 60 °C for 3 h. The reaction mixture was cooled to rt and was diluted with water (500

mL). The colorless precipitates were filtered and washed with water. The solid was dissolved in CHCl .
3
The solution was washed with brine, dried over MgSO , and evaporated to dryness. The solid product was
4
purified by recrystallization from CH Cl -diisopropyl ether (1:1) to afford 6 (56.83 g, 71 %) as colorless
2
2
9a
1
crystals, mp 168.5-169.5 °C (CH Cl -diisopropyl ether) (lit., 165-166 °C); H-NMR (400 MHz) δ 6.56
2
2
13
(s, 2H), 4.23 (d, 2H, J=8.5Hz), 3.78 (d, 2H, J=8.5Hz), 3.56 (s, 6H), 3.43 (s, 6H); C-NMR (100
+
MHz) δ 193.2, 89.7, 62.2, 45.4, 41.8; MS (EI) m/z 327 (M ).
2-Dimethyldithiocarbamyl-1,4-diox-2-ene (7).
A solution of 2,3-bis(dimethyldithiocarbamyl)-1,4-dioxane (6) (9.02 g, 27.6 mmol) in toluene (200 mL)
was heated under reflux for 15 h. The reaction mixture was cooled to room temperature and evaporated in
vacuo. The residue was purified by recrystallization from CH Cl -diisopropyl ether (1:1) to afford 7 (5.41
2
2
9a
1
g, 95 %) as colorless crystals, mp 169-169.5 °C (CH Cl -diisopropyl ether) (lit., 171 °C); H-NMR (400
2
2
13
MHz) δ 6.47 (s, 1H), 4.28-4.30 (m, 2H), 4.19-4.21 (m, 2H), 3.53 (s, 3H), 3.39 (s, 3H) ; C-NMR
(100 MHz) δ 195.1, 137.4, 128.0, 64.8, 64.2, 45.5, 41.7.
Bromination of 7 .
To a cooled solution of 7 (10.5 g, 53.2 mmol) in CH Cl (100 mL) was added dropwise a solution of Br
2
2
2
(2.8 mL, 54.3 mmol) in CH Cl (8 mL) at 0 °C and the mixture was stirred for 1 h. The orange
2
2
precipitates were filtered and washed with CH Cl to afford the bromide (8) (19.7 g, 98%) which was used
2
2
9a
1
for further transformation. 8: colorless crystals, mp 104-106 °C (CH Cl ) (lit., 105 °C); H-NMR
2
2
13
(DMSO-d , 400 MHz) δ 4.52 (s, 1H), 4.14-4.27 (m, 4H), 3.61 (s, 3H), 3.56 (s, 3H); C-NMR
6
(DMSO-d , 100 MHz) δ 183.9, 97.7, 96.9, 65.5, 60.7, 46.9, 46.9.
6
4,5-Ethylenedioxy-2-dimethylamino-1,3-dithiolium bromide (9).
The iminium salt 8 (18.1 g, 49.5 mmol) was placed in a 100-mL flask and heated 110 °C for 5 h under
reduced pressure (15 Torr) to afford 9 (14.0 g, 99 %) as pale brown microcrystals, mp 171.5-172 °C. UV
9a 1
13
(CH Cl ) λ
270, 360 nm ; H-NMR (DMSO-d , 400 MHz) δ 4.53 (s, 4H), 3.47 (s, 6H); C-NMR
6
2
2
max
(DMSO-d , 100 MHz) δ 174.2, 128.0, 64.5, 46.1.
6
4,5-Ethylenedioxy-1,3-dithiole-2-thione (10).
To a solution of 9 (4.98 g, 17.5mmol) in EtOH (130 mL) and AcOH (130 mL) was added portionwise
powdery NaSH (8.55 g, 153 mmol) with stirring. The reaction mixture was stirred at rt for 2 h and diluted
with a mixture of CH Cl (300 mL) and water (300 mL). The organic layer was separated and washed
2
2
with brine and saturated NaHCO solution successively. After dried MgSO , the organic solution was
3
4
concentrated in vacuo and the residue was purified by chromatography on silica gel using CH Cl -hexane
2
2
(1:1) as eluent. The eluent was concentrated to dryness and the residual solid was recrystallized from
1
CH Cl / hexane (1:1) to afford 10 (2.46 g, 73%) as yellow crystals, mp 144-144.5 °C; H-NMR (400
2
2
13
+
MHz) δ 4.38 (s, 4H); C-NMR (100 MHz) δ 174.2, 128.0, 67.5, 66.5; MS m/z 192(M ), 164, 128, 76;
-1
IR (KBr) 1597 (C=C), 1171 (C=S) cm ; HRMS calcd for C H O S 191.9374, found 191.9359.
5 4 2 3

4,5-Ethylenedioxy-4',5'-bis(methoxycarbonyl)tetrathiafulvalene (12).
A mixture of the thione (10) (300 mg, 1.56 mmol) and 11 (535 mg, 2.29 mmol) was heated in triethyl
phosphite (10 mL) at 60 °C under nitrogen for 4 h. After the reaction mixture was cooled to rt, triethyl
phosphite was removed under reduced pressure to give a black residue which was separated by column
chromatography on silica gel using CH Cl / hexane (1:1) as eluent to afford 12 (304 mg, 70%), together
2
2
with small anounts of bis(ethylenedioxy)tetrathiafulvalene (13) and tetrakis(methoxycarbonyl)-
9b
1
tetrathiafulvalene (14). 12: purple crystals, mp 125.5-126 °C (CH Cl -hexane) (lit., 122-123 °C); H-
2
2
13
NMR (400 MHz) δ 4.27 (s, 4H), 3.84 (s, 6H); C-NMR (100 MHz) δ 159.4, 131.8, 123.1, 108.7,
+
104.8, 66.1, 52.9; MS m/z 378 (M ), 350, 320, 264, 216.
4,5-Ethylenedioxytetrathiafulvalene (1).
A mixture of 12 (2.19 g, 5.8 mmol) and LiBr•H O (6.11 g, 58.3 mmol) in HMPA (176 mL) was
2
evacuated, and gaseous nitrogen was filled. The mixture was gradually heated from rt to 150 °C in a period
of 1.5 h with stirring and stirred for 15 min at 150 °C. The reaction mixture was cooled to rt and water was
added. The mixture was extracted with CS . The organic layer was washed with brine and dried over
2
MgSO , and the solvent was evaporated in vacuo. The residue was chromatographed on silica gel with
4
CS as eluent to afford 1 (1.06 g, 70%), together with the monoester (15) (371 mg, 20%). 1: red needles,
2
9a
1
13
mp 92.0-92.5 °C (CHCl -hexane) (lit., 92 °C); H-NMR (400 MHz) δ 6.33 (s, 2H), 4.26 (s, 4H); C-
3
+
NMR(100 MHz) δ 123.0, 118.8, 115.7, 98.4, 66.0; MS m/z 262 (M ), 234, 178, 146, 102; HRMS calcd
for C H O S 261.9251, found 261.9243. 15: red microcrystals, mp 166.5-167.0 °C (CH Cl -hexane);
8 6 2 4
2
2
1
+
H-NMR (400 MHz) δ 7.26 (s, 1H), 4.27 (s, 4H), 3.80 (s, 3H); MS m/z 320 (M ), 292, 246, 204;
HRMS calcd for C H O S 319.9306, found 319.9287. The monoester (15) was converted into 1
10 8 4 4
(50%) under the similar conditions described above.
4,5-Diiodo-4',5'-ethylenedioxytetrathiafulvalene (2) by Iodination of 1 .
To a solution of 1 (199 mg, 0.759 mmol) in THF (5 mL) was added LDA, which was prepared from
i
n
Pr NH (372 mg, 3.69 mmol) and Bu Li (1.0 mL, 1.6 mmol, 1.6 M in hexane) in THF (2 mL), at -78 °C
2
during 7 min under argon. The color of solution was changed to intensely orange. After being stirred at
-78 °C for 50 min, perfluorohexyl iodide (1.24 g, 2.77 mmol) in THF (3 mL) was added at -78 °C during 7
min. The resulting red solution was stirred for 1 h at -78 °C and then was allowed to warm to rt. Saturated
aq NH Cl was added and the mixture was extracted with CS . The organic layer was washed with brine
4
2
and dried over MgSO , and the solvent was evaporated in vacuo. The residue was chromatographed on
4
silica gel with CS as eluent and was further purified by GPC to afford 2 (215 mg, 55%). 2: red needles,
2
1
13
mp 150 °C (decomp) (CH Cl -hexane); H-NMR (400 MHz) δ 4.26 (s, 4H); C-NMR (125 MHz) δ
2
2
+
123.1, 117.8, 103.4, 77.2, 66.1; MS m/z 514 (M ), 388, 260; HRMS calcd for C H O I S 513.7182,
8 4 2 2 4
found 513.7166.
4,5-Ethylenedioxy-4'-iodotetrathiafulvalene (18) by Iodination of 1 .
In a similar manner for the preparation of 2, 1 (82 mg, 0.313 mmol) in THF (10 mL) was treated with
i
n
LDA from Pr NH (56 mg, 0.555 mmol) and Bu Li (0.35 mL, 0.37 mmol, 1.06 M in hexane) in THF (2
2

mL) at -78 °C under argon. After being stirred at -78 °C for 50 min, F ClCCFClI (253 mg, 0.94 mmol) in
2
THF (3 mL) was added and the reaction mixture was stirred for 1 h at -78 °C and then was allowed to warm
to rt. After aqueous work-up, 18 (100 mg, 82%) was isolated by column chromatography on silica gel
with CS as eluent, followed by GPC separation. 18: orange needles, mp 78-79 °C (decomp) (CH Cl -
2
2
2
1
13
hexane); H-NMR (400 MHz) δ 6.43 (s, 1H), 4.34 (s, 4H); C-NMR (125 MHz) δ 124.0, 123.2, 123.1,
+
116.8, 100.6, 66.2, 63.7; MS m/z 388 (M ), 360; HRMS calcd for C H O IS 387.8217, found
8 5 2
4
387.8223.
4,5-Dibromo-4',5'-ethylenedioxytetrathiafulvalene (3) by Bromination of 1 .
In a similar manner for the preparation of 2 , 1 (300 mg, 1.14 mmol) in THF (5 mL) was treated with LDA
i
n
from Pr NH (350 mg, 3.47 mmol) and Bu Li (1.5 mL, 2. 45 mmol, 1.6 M in hexane) in THF (3 mL) at
2
-78 °C under argon. After stirred at -78 °C for 40 min, BrCl CCCl Br (830 mg, 2.55 mmol) in THF (3
2
2
mL) was added. After stirring at -78 °C to rt and then work-up, 3 (354 mg, 74%) was isolated by column
chromatography on silica gel with CS as eluent, followed by GPC separation. 3: red needles, mp 169-
2
1
13
170 °C (CH Cl -hexane); H-NMR (500 MHz) δ 4.27 (s, 4H); C-NMR (125 MHz) δ 123.2, 110.2,
2
2
+
79
105.6, 101.6, 66.3; MS m/z 424, 422, 420 (M ), 368, 303, 260; HRMS calcd for C H O Br81BrS
8 4 2
4
421.7420, found 421.7403.
4,5-Dichloro-4',5'-ethylenedioxytetrathiafulvalene (4) by Chlorination of 1 .
In a similar manner for the preparation of 2, 1 (201 mg, 0.77 mmol) in THF (5 mL) was treated with LDA
i
n
[Pr NH (350 mg, 3.47 mmol), Bu Li (1.5 mL, 2.45 mmol, 1.6 M in hexane), and THF (3 mL)]. After
2
being stirred for 1 h at -78 °C, Cl CCCl (498 mg, 2.10 mmol) in THF (3 mL) was added. After stirring
3
3
for 1.7 h at -78 °C and then rt, 4 (142 mg, 56%) was isolated by column chromatography on silica gel with
1
CS as eluent, followed by GPC separation. 4: red needles, mp 177.5-178 °C (CH Cl -hexane); H-NMR
2
2
2
13
(500 MHz) δ 4.27 (s, 4H); C NMR (125 MHz) δ 123.2, 114.2, 106.8, 105.8, 66.3; MS m/z 334, 332,
+
35
330 (M ), 214; HRMS calcd for C H O Cl S 329.8471, found 329.8456.
8 4 2
2 4
4,5-Dibromo-1,3-dithiole-2-thione (20b).
n
To a solution of 19 (674 mg, 5.02 mmol) in THF (40 mL) was added Bu Li (3.3 mL, 5.05 mmol, 1.53 M
in hexane) at -78 °C under argon. The mixture was stirred for 1 h at -78 °C. To the mixture was added
BrCl CCCl Br (3.75 g, 10.99 mmol) in THF (20 mL) at -78 °C and the resulting mixture was stirred for 3
2
2
h at -78 °C, allowed to warm to rt, and stirred at rt overnight. After aqueous work-up, the product was
separated by column chromatography on silica gel using CS -hexane (1:1) as eluent to afford 20b (462
2
13
mg, 32%). 20b: yellow needles, mp 100.3-100.8 °C (CH Cl -hexane); C-NMR (125 MHz) δ 208.7,
2
2
+
-1
81
107.2; MS m/z 294, 292, 290 (M ); IR (KBr) 1505 cm ; HRMS calcd for C Br S 293.7488, found
3
2 3
293.7494.
4,5-Dibromo-1,3-dithiole-2-one (17b).
To a solution of 20b (1.40 g, 4.78 mmol) in a mixture of CHCl (100 mL) and acetic acid (100 mL) was
3
added mercury(II) acetate (4.65 g, 14.6 mmol) under nitrogen. The reaction mixture was stirred for 2 h at

rt. The resultant white precipitates were filtered off and washed with CHCl . The filtrate was washed with
3
brine several times and then with sat. aq. NaHCO solution to remove acetic acid. The organic layer was
3
dried over MgSO and the solvent was evaporated in vacuo. The residue was passed through a short colum
4
of silica gel with CH Cl as eluent to afford 17b (1.26 g, 95%). 17b: colorless needles, mp 67.0-67.5 °C
2
2
13
+
-
(CH Cl -hexane); C-NMR (125 MHz) δ 188.5, 100.5; MS m/z 278, 276, 274 (M ); IR (KBr) 1665 cm
2
2
1
81
; HRMS calcd for C Br OS 277.2243, found 277.2216.
3
2
2
4,5-Diiodo-4',5'-ethylenedioxytetrathiafulvalene (2) by Cross-coupling.
A mixture of the thione (10) (199 mg, 1.03 mmol), the diiodide (17a) (374 mg, 1.01 mmol), and
P(OCH ) (5 mL) was heated in refluxing benzene (10 mL) for 4 h. After the reaction mixture was cooled
3 3
to rt, the solvent was removed under reduced pressure and the residue was chromatographed on silica gel
using CS -hexane (1:1) as eluent to afford EDO-TTFI 2 (304 mg, 59%), together with
2
2
tetraiodotetrathiafulvalene (TTFI ) (104 mg, 29%).
4
4,5-Dibromo-4',5'-ethylenedioxytetrathiafulvalene (3) by Cross-coupling.
In a similar manner for the reaction of 10 with 17a, the reaction of 10 (182 mg, 0.95 mmol) with 17b
(250 mg, 0.91 mmol) formed EDO-TTFBr 3 (228 mg, 59%), together with TTFBr (74 mg, 15%) and
2
4
BEDO-TTF (13 mg, 4%).
X-Ray Structural Determination of 2 (Figure 1 ) .
Crystals of 2 suitable for X-Ray structure analysis were obtained by slow recrystallization of 2 from
(hexane-CH Cl ), C H O I S , red needle of crystal size 0.12 x 0.14 x 0.30 mm; intensity data were
2
2
8 4 2 2 4
collected using a Rigaku AFC7R four-circle diffractometer with graphite-monochromated Mo-K radiation
α
(λ = 0.71069); crystal system orthorhombic, space group Pna2 (No. 33); cell parameters: a = 14.561(1), b
1
3
-3
= 15.324(1), c = 12.046(2); V = 2687.8(4) Å ; Z = 8; D
= 2.541 g cm ; no. of reflections measured
calcd
with I > 3.00σ(I) 2001; R = 0.045, R = 0.044. Structural parameters of non-hydrogen atoms were
w
refined anisotropically according to the full-matrix least-squares technique.
X-Ray Structural Determination of 4 (Figure 2 ) .
Crystals of 4 were obtained by slow recrystallization of 4 from (hexane-CH Cl ), C H O Cl S , red
2
2
8 4 2 2 4
needle of crystal size 0.60 x 0.18 x 0.06 mm; intensity data were collected under the similar conditions
described for 2; crystal system monoclinic, space group C (No. 15); cell parameters: a = 26.22(3), b =
2/c
3
-3
4.01(9), c = 22.62(3); β = 107.8(1)°; V = 2261(49) Å ; Z = 8; D
= 1.946 g cm ; no. of reflections
calcd
measured with I > 3.00σ(I) 1551; R = 0.068, R = 0.051. Structural parameters of non-hydrogen atoms
w
were refined anisotropically according to the full-matrix least-squares technique.
-
X-Ray Structural Determination of (2) •I (I ) (Figure 3 ) .
2
2
2
-
n
Crystals of (2) •I (I ) were obtained by the galvanostatic oxidation (ca. 1 µA) of 2 with Bu NI in
2 2
2
4
3
chlorobenzene, C H O I S , black prism of crystal size 0.12 x 0.08 x 0.20 mm; intensity data were
8 4 2 4 4
collected under the similar conditions described for 2; crystal system monoclinic, space group P2 /a (No.
1

3
14); cell parameters: a = 11.196(2), b = 11.835(3), c = 13.392(2); β = 110.00(1)°; V = 1667.5(6) Å ; Z =
-3
4; D
= 3.059 g cm ; no. of reflections measured with I > 3.00σ(I) 2579; R = 0.033, R = 0.031.
calcd
w
X-Ray Structural Determination of (2) •ClO (Figure 4 ) .
2
4
n
Crystals of (2) •ClO were obtained by the galvanostatic oxidation (ca. 1 µA) of 2 with Bu NClO in
2
4
4
4
chlorobenzene, C H O ClI S , black needle of crystal size 0.40 x 0.08 x 0.08 mm; intensity data were
16 8 8
4 8
collected under the similar conditions described for 2; crystal system orthorhombic, space group Cmma
(No. 67); cell parameters: a = 7.14(1), b = 13.178(1), c = 15.628(2); V = 1469(2) Å3; Z = 2; D
=
calcd
-3
2.548 g cm ; no. of reflections measured with I > 3.00σ(I) 2343; R = 0.037, R = 0.054. Structural
w
parameters of non-hydrogen atoms were refined anisotropically according to the full-matrix least-squares
technique.
X-Ray Structural Determination of 18•TCNQ (Figure 6 ) .
Crystals of 18•TCNQ were obtained by mixing a solution of 18 in CHCl with a solution of TCNQ in
3
MeCN, C H N O IS , black prism of crystal size 0.30 x 0.25 x 0.32 mm; intensity data were collected
14 6 2 2
4
under the similar conditions described for 2; crystal system monoclinic, space group P2 /a (No. 14); cell
1
3
parameters: a = 8.176(3), b = 16.247(2), c = 12.967(2); β = 103.25(1)°; V = 1676.5(6) Å ; Z = 4; D
=
calcd
-3
1.939 g cm ; no. of reflections measured with I > 3.00σ(I) 2938; R = 0.030, R = 0.029. Structural
w
parameters of non-hydrogen atoms were refined anisotropically and some hydrogen atoms were refined
isotropically according to the full-matrix least-squares technique.
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