An Iterative Strategy for the Synthesis of Oligothiophenes by Catalytic Cross-Coupling Reactions

Article abstract of DOI:10.1002/hc.10224

An iterative strategy for the synthesis of new sulfur-functionalized oligothiophenes by Suzuki or Stille cross-coupling reactions was applied to the reaction of 4-bromo-tert-butylphenylthioether with thiophene derivatives. The planarity of the oligothiophenes obtained was confirmed by the single-crystal X-ray structure analysis of 2-(4′-tert-butyl-thiophenyl)thiophene, which shows a potentially large electronic conjugation length.

Full text of DOI:10.1002/hc.10224

Heteroatom Chemistry
Volume 15, Number 2, 2004
An Iterative Strategy for the Synthesis of
Oligothiophenes by Catalytic Cross-Coupling
Reactions
Thomas Pinault, Fre´de´ric Che´rioux, Bruno Therrien,
and Georg Su¨ss-Fink
Institut de Chimie, Case Postale 2, CH-2007 Neuchaˆtel, Switzerland
Received 5 September 2003
molecular-scale electronic devices have been inves-
ABSTRACT: An iterative strategy for the synthe-
tigated in particular, in the case of Self Assembled
sis of new sulfur-functionalized oligothiophenes by
Monolayers built around a gold-surface and thiol-
Suzuki or Stille cross-coupling reactions was applied
ended organic compounds or for the development
to the reaction of 4-bromo-tert-butylphenylthioether
of surface-bound molecular motor [7]. However, the
with thiophene derivatives. The planarity of the olig-
insertion of a sulfur atom in oligomers as an an-
othiophenes obtained was confirmed by the single-
chor leads to a modification of the electronic struc-
crystal X-ray structure analysis of 2-(4ꢀ-tert-butyl-
ture of the starting oligomers [8,9]. In this paper,
thiophenyl)thiophene, which shows a potentially large
we propose an iterative strategy for the synthesis of
ꢁ
C
electronic conjugation length. 2004 Wiley Periodicals,
monodisperse oligothiophenes ending with a 4-tert-
butylphenylthioether group.
Inc. Heteroatom Chem 15:121–126, 2004; Published online
in Wiley InterScience (www.interscience.wiley.com). DOI
10.1002/hc.10224
RESULTS AND DISCUSSION
The common method to synthesize monodisperse
INTRODUCTION
and well-defined oligomers is based on a step-by-step
During the last two decades, well-defined, monodis-
perse oligothiophenes have been extensively stud-
ied as model compounds in order to understand
and to optimize the electronic, optical, and charge
transport properties of conjugated polymers such as
polythiophenes and their derivatives [1–4]. In ad-
dition, oligothiophenes themselves exhibit intrinsic
physical properties due to their well-defined struc-
ture and their large conjugation length. These ef-
fects led to the development of thiophene-based elec-
tronic devices such as electroluminescent diodes [5]
or field-effect transistors [6]. On the other hand, the
strategy in which a catalytic cross-coupling reaction
such as Suzuki, Stille, or Kumada coupling leads
to the elongation of the oligomer by one constitu-
tive subunit. However, in the case of the presence of
a thiophenol derivative, the free thiol function can
be considered as a poison for the palladium catalyst
used for the cross-coupling reaction. Therefore, the
first step of our synthetic strategy consists in the pro-
tection of the free-thiol function by tert-butyl moiety,
catalyzed by aluminum trichloride (Scheme 1).
(4-Bromo)phenyl-tert-butylthioether 2 is ob-
tained in quantitative yield, and the spectroscopic
1
data (1H or 13C{ H} NMR) are in accordance with
the literature data [10]. This compound can be used
as starting material for the generation of oligothio-
phenes, thanks to the presence of a bromo atom.
Correspondence to: Fre´de´ric Che´rioux; e-mail: frederic.
cherioux@unine.ch.
c
ꢁ
2004 Wiley Periodicals, Inc.
121

122 Pinault et al.
SCHEME 1 Synthesis of (4-bromo)phenyl-tert-butylthio-
ether 2.
Two different cross-coupling reactions were tested:
Suzuki cross-coupling with commercially available
2-thiophene boronic acid (Scheme 2) and Stille
cross-coupling with tri-n-butyltinthiophene deriva-
tives 6–8 (Scheme 3).
The tin-functionalized compounds 6–8 were
synthesized from the reaction of the lithium
salt of the thiophene 3, 2,2ꢀ-bithiophene 4, and
3,4-ethylenedioxythiophene 5, respectively, with
tri-n-butyltin chloride [see experimental]. These
compounds were used without further purification
as starting material for the Stille cross-coupling
reaction.
FIGURE 1 ORTEP drawing of compound 9. Ellipsoids are
drawn at the 50% probability level. Selected bond lengths
◦
˚
(A) and angles ( ): C(1) S(1) 1.693(3), C(4) S(1) 1.697(3),
C(4) C(5) 1.485(4), C(8) S(2) 1.775(3), C(11) S(2)
1.857(3), C(1) S(1) C(4) 92.39(14), C(8) S(2) C(11)
103.48(12), S(1) C(4) C(5) 110.6(2), C(3) C(4) C(5)
127.6(2).
functionalized (boronic or tri-n-butyltin) thiophene
derivatives. This was achieved at room temperature
by the reaction of compounds 9 and 10 with N-
bromosuccinimide in acetic acid/chloroform mix-
ture (Scheme 4).
All products were obtained in good yield (75–
90%), and they were characterized by their MS and
Products 12 and 13 were obtained in good yield
(>90%) and characterized by their MS and NMR
1
NMR spectroscopic data (1H and 13C{ H} NMR).
1
spectroscopic data (1H and 13C{ H} NMR). Com-
Suitable crystals of 9 were obtained from the result-
ing oil at 4◦C after chromatography on silica gel.
The molecular structure of 9 is presented in
Fig. 1. The bond lengths and angles are in accor-
dance with those in related structures [11,12]. The
phenyl-thienyl unit is almost planar, with the mean
deviation from the least-square plane formed by S(1),
pound 12 was used as starting material for Suzuki
or Stille cross-coupling reaction with 2-thiophene
boronic acid and 2-tri-n-butyltinthiophene 6, respec-
tively (Scheme 5).
The two types of cross-coupling reactions gave
the same product which can be obtained alter-
natively by direct Stille cross-coupling reaction
between 2 and 7. This could be explored as a fast syn-
thetic way for tert-butylthiophenyl-terminated olig-
othiophenes in which the length of the ꢀ-conjugated
system is controlled step-by-step.
These reactions demonstrate that an oligothio-
phene can be elongated by several units from suc-
cessive brominations and cross-coupling reactions
(Suzuki- or Stille-type). In principle, each sulfur-
functionalized oligothiophene should be accessible
by this iterative strategy (Scheme 6).
˚
S(2), and C(1) to C(10) being 0.0395 A. The dihedral
angle between the phenyl and thienyl rings is only
4.9(1)˚, whereas in the bis[4-(5-methoxycarbonyl-2-
thienyl)phenyl] sulfide analogue the dihedral angle
was 10.9(1)◦ [11]. Moreover, this weak torsional an-
gle is ideal for an important ꢀ-ꢀ overlapped structure
as requested for optimal charge transport in conju-
gated oligomers. It is very close to the correspond-
ing angle observed in the case of ꢁ-sexithiophene
(4.1◦) [5] and smaller than in standard unsubstituted
thiophene-phenylene (18◦–20◦) [13]. Intermolecular
contact involving the C(3) H atom and S(2) leads to
the formation of infinite chains running parallel to
the a axis of the crystal.
EXPERIMENTAL
General Remarks
In the view of developing longer oligomers, the
insertion of a bromine atom was necessary, in or-
der to allow a second cross-coupling reaction with
All reactions were carried out under nitrogen by
using standard Schlenk techniques. The solvents
were degassed prior to use. 2,2ꢀ-bithiophene has
been synthesized by Stille cross-coupling reac-
tion between 2-bromothiophene and 2-(tri-n-butyl)-
thiophene [3].All other reagents were purchased
(Acros and Aldrich) and used as received. NMR
spectra were recorded with a Varian Gemini 200
BB instrument and referenced to the signals of the
SCHEME
2
Synthesis of 2-(4ꢀ-tert-butylthiophenyl)-
thiophene 9 by Suzuki cross-coupling reaction.

An Iterative Strategy for the Synthesis of Oligothiophenes by Catalytic Cross-Coupling Reactions 123
SCHEME 3 Synthesis of thiophene derivatives 9–11 by Stille cross-coupling reaction.
SCHEME 4 Bromination of compounds 9 and 10.
SCHEME 5 Elongation of 12 by Suzuki or Stille cross-coupling reaction.

124 Pinault et al.
SCHEME 6 Synthetic route toward one higher generation order.
residual protons in the deuterated solvents. The mass
spectra were recorded at the University of Fribourg
(Switzerland) by Prof. Titus Jenny. Microanalyses
were carried out by the Laboratory of Pharmaceu-
tical Chemistry, University of Geneva (Switzerland).
10 mmol) was slowly added and the reaction was left
under strong stirring at −20◦C for 1 h, and then 10
mmol of Sn-n-Bu3Cl were added. The mixture was
refluxed overnight. After cooling to room temper-
ature, the mixture was poured into water and ex-
tracted with CH2Cl2 (3 × 20 ml). The combined or-
ganic layers were then washed with water (3 × 20
ml), dried over anhydrous MgSO4, and the solvent
was removed under reduced pressure to give pure
colorless 6, green 7, and brown 8 oils which were
used without further purification.
(4-Bromo)phenyl-tert-butylthioether (2)
To a slurry of 4-bromothiophenol 1 (5 g, 26.5 mmol)
in 2-chloro-2-methylpropane (20 ml) was added
aluminum chloride (175 mg, 1.3 mmol) in small
portions at room temperature. The reaction be-
came vigorously foaming and HCl was exhausted.
The mixture was stirred for one additional hour,
and the solution became orange. The reaction mix-
ture was poured into water and extracted with n-
pentane (3 × 25 ml). The combined organic layers
were washed with water (3 × 30 ml), dried over anhy-
drous MgSO4, and the solvent was removed under re-
duced pressure. The purification of the residual light
yellow oil was done using column chromatography
2-(Tri-n-butyltin)thiophene (6)
1H NMR (200 MHz, CDCl3): δ 0.91 t (9H, CH3-CH2
3 JH 8.06 Hz), 1.12 t (6H, Sn-CH2-CH2 3 JH 8.06
H
H
Hz), 1.31 h (6H, CH3-CH2-CH2 3 JH 8.06 Hz), 1.57
H
quint. (6H, Sn-CH2-CH2-CH2 3 JH 8.06 Hz), 7.22 dd
H
(1H, C(4)H 3 JH(4)
3.66 Hz 3 JH(4) H(5)4.82 Hz), 7.26
H(3)
3
d (1H, C(3)H JH(3)
3.66 Hz), 7.58 d (1H, C(5)H
H(4)
3 JH(5)
4.82 Hz).
H(4)
˚
(silica gel 60A, n-pentane) to afford colorless oil with
quantitative yield. 1H NMR (200 MHz, CDCl3) ꢂ 1.30
s (9H, C(CH3)3), 7.41 d (2H, C(2)H 3 JH(2)
8.8 Hz),
H(3)
5-(Tri-n-butyltin)-2,2ꢀ-bithiophene (7)
3
7.49 d (2H, C(3)H JH(3)
8.8 Hz); 13C NMR (50
H(2)
MHz, CDCl3) ꢂ 31.23, 46.24, 123.76, 131.92, 132.18,
139.22.
δ 0.91 t (9H, CH3-CH2 3 JH 8.06 Hz), 1.12 t (6H, Sn-
H
CH2-CH2 3 JH 8.06 Hz), 1.31 h (6H, CH3-CH2-CH2
H
3 JH
8.06 Hz), 1.57 quint. (6H, Sn-CH2-CH2-CH2
H
3 JH 8.06 Hz), 7.02 dd (1H, C(4ꢀ)H JH(4 )
3
ꢀ
ꢀ
3.66
H
3
H(3 )
General Procedure for the 2-Stannylation
of Thiophene Derivatives
Hz JH(4 ) H(5 )4.86 Hz), 7.09 d (1H, C(3ꢀ)H JH(3 )
3
ꢀ
ꢀ
ꢀ
ꢀ
H(4 )
3.66 Hz), 7.20 d (1H, C(5ꢀ)H JH(5 )
4.82 Hz),
3
ꢀ
ꢀ
H(4 )
3
Thiophene derivatives (10 mmol) 3–5 were dissolved
into Et2O (20 ml) at −20◦C. n-BuLi (1.6 M in hexane,
7.22 d (1H, C(3)H JH(3) H(4)3.69), 7.32 d (1H, C(4)H
3 JH(4)
3.69).
H(3)

An Iterative Strategy for the Synthesis of Oligothiophenes by Catalytic Cross-Coupling Reactions 125
4.02), 7.57 s (4H, C(2ꢀꢀ)H and C(3ꢀꢀ)H); 13C NMR (50
3,4-Ethylenedioxy-2-(tri-n-butyltin)thiophene
MHz, CDCl3) δ 31.25, 46.56, 124.06, 124.52, 124.83,
124.96, 125.65, 128.19, 132.22, 134.62, 137.53,
138.22, 142.43. MS (ESI): m/z = 330.
(8)
0.91 t (9H, CH3-CH2 3 JH
8.06 Hz), 1.12 t (6H,
H
Sn-CH2-CH2 3 JH 8.06 Hz), 1.31 h (6H, CH3-CH2-
H
CH2 3 JH 8.06 Hz), 1.57 quint. (6H, Sn-CH2-CH2-
H
CH2 3 JH
8.06 Hz), 4.10 m (2H, O-CH2-CH2-O),
H
5-(4ꢀ-tert-Butylthiophenyl)-2,2ꢀ-bithiophene (10)
by Stille Cross-Coupling
4.17 m (2H, O-CH2-CH2-O), 6.60 s (1H, C(5)H).
(4-Bromo)phenyl-tert-butylthioether
2 (1 g, 4.0
2-(4ꢀ-tert-butylthiophenyl)thiophene (9) by Stille
mmol), 7 (1.82 g, 4.0 mmol), and tetrakis(triphenyl-
phosphine)palladium(0) (100 mg, 0.4 mmol) were
dissolved in dry toluene (20 ml). The mixture was
refluxed overnight. After cooling to room tempera-
ture, the solution was washed with an aqueous sat-
urated solution of NH4Cl (100 ml), then extracted
three times with 100 ml of Et2O, and the solvent
was removed under reduced pressure. The resulting
oil was purified by column chromatography (silica
Cross-Coupling
(4-Bromo)phenyl-tert-butylthioether 2 (1 g, 4.0
mmol) in dry toluene (20 ml), 2-(tri-n-butyltin)-
thiophene 6 (0.995 ml, 4.0 mmol), and tetrakis-
(triphenylphosphine)palladium(0) (100 mg, 0.4
mmol) were refluxed overnight. After cooling to
room temperature, the solution was washed with
an aqueous saturated solution of NH4Cl (100 ml),
and then extracted three times with 100 ml of Et2O.
The organic layers were dried over MgSO4 and
removed under reduced pressure. The resulting oil
was purified by column chromatography (silica gel
◦
˚
gel 60 A, petroleum ether bp. 60–90 C) and yielded
to a colorless oil. The spectroscopic data are iden-
tical with those obtained by Suzuki cross-coupling
reaction.
◦
˚
60 A, petroleum ether bp. 60–90 C) and yielded
a colorless oil that crystallized after one night at
2-(4ꢀ-tert-Butylthiophenyl)-3,4-ethylenedioxy-
thiophene (11)
4◦C. 1H NMR (200 MHz, CDCl3) δ = 1.34 s (9H,
3
C(CH3)3), 7.12 dd (1H, C(4)H JH(4)
3.66 Hz
H(3)
3
3 JH(4)
5.13 Hz), 7.32 d (1H, C(3)H JH(3)
3.66
(4-Bromo)phenyl-tert-butylthioether
2 (1 g, 4.0
H(5)
H(4)
3
Hz), 7.34 d (1H, C(5)H JH(5)
5.13 Hz), 7.56 d
mmol), 8 (1.12 ml, 4.0 mmol), and tetrakis(tri-
phenylphosphine)palladium(0) (100 mg, 0.4 mmol)
were dissolved in dry toluene (20 ml). The mixture
was refluxed overnight. After cooling to room tem-
perature, the solution was washed with an aqueous
saturated solution of NH4Cl (100 ml), and then ex-
tracted three times with 100 ml of Et2O and the
solvent was removed under reduced pressure. The
resulting oil was purified by column chromatogra-
H(4)
(2H, C(2ꢀ)H JH(2 )
11.91 Hz), 7.56 d (2H, C(3ꢀ)H
ꢀ
3
ꢀ
H(3 )
3
JH(3 )
11.91 Hz); 13C NMR (50 MHz, CDCl3) δ
ꢀ
ꢀ
H(2 )
31.25, 46.50, 123.85, 125.62, 126.05, 128.45, 128.63,
132.07, 135.02, 138.22. MS (ESI): m/z = 248.
5-(4ꢀ-tert-Butylthiophenyl)-2,2ꢀ-bithiophene (10)
by Suzuki Cross-Coupling
5-Bromo-2-(4ꢀ-tert-butylthiophenyl)thiophene
12
◦
˚
phy (silica gel 60 A, petroleum ether bp. 60–90 C)
(400 mg, 1.2 mmol), 2-thiopheneboronic acid (230
mg, 1.8 mmol), and sodium carbonate (191 mg, 1.8
mmol) were dissolved in EtOH (20 ml), and then
tetrakis(triphenylphosphine)palladium(0) (69 mg,
0.06 mmol) was added. The reaction mixture was
refluxed, then poured in water (70 ml), extracted
with CH2Cl2 (3 × 25 ml), and the recombined or-
ganic layers were washed with water, dried over
MgSO4, and the solvent was removed under reduced
pressure. The purification was done using column
1
and yielded to a colorless powder. H NMR (CDCl3,
200 MHz) δ 1.19 s (9H, C(CH3)3), 4.10 m (2H, O-
CH2-CH2-O), 4.17 m (2H, O-CH2-CH2-O), 6.60 s (1H,
C(5)H) 7.28 d (2H, C(2ꢀ)H 3 JH(2 )
ꢀ
ꢀ
8.79 Hz), 7.41 d
H(3 )
(2H, C(3ꢀ)H JH(3 )
8.79 Hz); 13C NMR (50 MHz,
3
ꢀ
ꢀ
H(2 )
CDCl3) δ 31.22, 46.32, 64.63, 65.05, 98.48, 117.02,
125.94, 130.84, 133.94, 137.93, 138.93, 142.56. MS
(ESI): m/z = 366.
5-Bromo-2-(4ꢀ-tert-butylthiophenyl)thiophene
(12)
5-(4ꢀ-tert-Butylthiophenyl)thiophene 9 (425 mg, 1.7
mmol) and N-bromosuccinimide (308 mg, 1.7
mmol) were dissolved in chloroform (10.0 ml) and
acetic acid (10.0 ml). The mixture was stirred in
the absence of light for 6 h. The aqueous layer was
˚
chromatography (silica gel 60 A, petroleum ether
(bp. 60–90◦C)/CH2Cl2 3:1) and yielded to a yellowish
1
solid. H NMR (200 MHz, CDCl3) δ = 1.25 s (9H,
3
C(CH3)3), 7.06 dd (1H, C(4)H JH(4)
3.66 Hz
H(3)
3
3 JH(4)
5.12 Hz), 7.18 d (1H, C(3)H JH(3)
3.66
H(5)
H(4)
Hz), 7.23 d (1H, C(5)H 3 JH(5) H(4) 5.13 Hz), 7.22 d (1H,
C(3ꢀ)H 3 JH(3 )
4.02), 7.32 d (1H, C(4ꢀ)H 3 JH(4 )
ꢀ
ꢀ
ꢀ
ꢀ
H(4 )
H(3 )

126 Pinault et al.
◦
˚
extracted with ether (30 ml), then the combined
organic layers were washed multiple times with
water (50 ml), and dried over magnesium sulfate.
The solvent was removed under reduced pressure,
and the residual oil was purified by column chro-
matography (silica gel, petroleum ether 60–90◦C,
then petroleum ether 60–90◦C/CH2Cl2 10:1). 1H NMR
radiation (ꢃ = 0.71073 A) with φ range 0–200 , in-
crement of 1.5◦, 2θ range from 2.0–26◦, Dmax-Dmin
˚
= 12.45-0.81 A. The structure was solved by direct
methods using the program SHELXS-97 [14]. The
refinement and all further calculations were carried
out using SHELXL-97 [15]. The H-atoms were in-
cluded in calculated positions and treated as rid-
ing atoms using the SHELXL default parameters.
The non-H atoms were refined anisotropically, us-
ing weighted full-matrix least-square on F2. Figure 1
was drawn with the ORTEP program [16].
(CDCl3, 200 MHz) δ = 1.11 s (9H, C(CH3)3), 7.04 d
3
(1H, C(4)H JH(4)
3.66 Hz), 7.09 d (1H, C(3)H
H(3)
3 JH(3)
3.66 Hz), 7.47 d (2H, C(2ꢀ)H JH(2 )
3
ꢀ
ꢀ
H(4)
H(3 )
8.58 Hz), 7.54 d (2H, C(3ꢀ)H JH(3 )
8.58 Hz); 13C
3
ꢀ
ꢀ
H(2 )
NMR 21.11, 31.20, 123.98, 125.65, 128.63, 131.27,
132.66, 134.15, 138.25, 145.27. MS (ESI): m/z = 327.
CCDC-218223 (9) contains the supple-
mentary crystallographic data for this paper.
These data can be obtained free of charge at
www.ccdc.cam.ac.uk/conts/retrieving.html
[or
5ꢀ-Bromo-5-(4ꢀꢀ-tert-butylthiophenyl)-2,2ꢀ-
bithiophene (13)
from the Cambridge Crystallographic Data Cen-
tre, 12, Union Road, Cambridge CB2 1EZ, UK;
fax: (internat.) +44−1223/336-033; E-mail: de-
posit@ccdc.cam.ac.uk].
5-(4ꢀ-tert-Butylthiophenyl)-2,2ꢀ-bithiophene 10 (82
mg, 0.25 mmol), and N-bromosuccinimide (44.5 mg,
0.25 mmol) were dissolved in chloroform (10.0 ml)
and acetic acid (10.0 ml). The mixture was stirred
in the absence of light for 6 h. The aqueous layer
was extracted with ether (30 ml), then the combined
organic layers were washed multiple times with wa-
ter (50 ml), and dried over magnesium sulfate. The
solvent was removed under reduced pressure, and
the residual oil was purified by column chromatog-
raphy (silica gel, petroleum ether 60–90◦C). 1H NMR
REFERENCES
[1] Roncali, J. Acc Chem Res 2000, 33, 147.
[2] Gronendaal, L. B.; Zotti, G.; Aubert, P.-H.; Waybrigth,
S. M.; Reynolds, J. R. Adv Mater 2003, 15, 855.
[3] Roncali, J. Chem Rev 1997, 97, 173.
[4] Mu¨llen, K.; Wegner, G. Electronic Materials: The
Oligomer Approach; Wiley-VCH: Weinheim, 1998.
[5] Fichou, D. J Mater Chem 2000, 10, 571.
[6] Ponomarenko, A.; Kirchmeyer, S.; Elschner, A.;
Huisman, B.-H.; Karbach, A.; Dreschler, D. Adv Funct
Mater 2003, 13, 591.
[7] Jian, H.; Tour, J. M. J Org Chem 2003, 68, 5091.
[8] Hicks, R. G.; Nodwell, M. B. J Am Chem Soc 2000,
122, 6746.
[9] Yaliraki, S. N.; Kemp, M.; Ratner, M. A. J Am Chem
Soc 1999, 121, 3428.
(CDCl3, 200 MHz) δ = 1.34 s (9H, C(CH3)3), 6.97 d
3
(1H, C(4)H JH(4)
4.02 Hz), 7.02 d (1H, C(3)H
H(3)
3
3 JH(3)
3.66 Hz), 7.12 d (1H, C(5)H JH(5)
5.13
H(4)
H(4)
Hz), 7.27 d (1H, C(3ꢀ)H JH(3 )
3
ꢀ
ꢀ
4.02), 7.57 s (4H,
H(4 )
C(2ꢀꢀ)H and C(3ꢀꢀ)H); 13C NMR (50 MHz, CDCl3) δ
31.25, 46.56, 124.06, 124.52, 124.83, 124.96, 125.65,
128.19, 128.64, 132.22, 134.62, 137.53, 138.22. MS
(ESI): m/z = 409.
[10] Adams, R.; Ferreti, A. J Am Chem Soc 1959, 81,
4927.
[11] Usman, A.; Razak, I. A.; Chantrapromma, S.; Fun,
H.-K.; Pan, D.; Ray, J. K. Acta Crystallogr E 2001, 57,
o842–o843.
[12] Sammer, W.; Gompper, R.; Polborn, K. Private com-
munication, 2003, CCDC 206522. Sammer, W., Ph.D.
Thesis, LMU Munich 1996.
[13] Fachetti, A.; Yoon, M.-H.; Stern, C. L.; Katz, H. E.;
Marky, T. J. Angew Chem, Int Ed Engl 2003, 42,
3900.
[14] Sheldrick, G. M. Acta Crystallogr A 1990, 46, 467.
[15] Sheldrick, G. M. SHELXL-97, University of
Go¨ttingen, Go¨ttingen, Germany, 1999.
X-ray Crystallographic Study
X-ray data for 9; C14H16S2, M = 248.39 g mol−1,
orthorhombic, P212121 (no. 19), a = 8.204(2), b =
3
˚
˚
10.846(2), c = 14.825(3) A, U = 1319.1(5) A , T =
153 K, Z = 4, µ (Mo Kα) = 0.374 mm−1, 2554 reflec-
tions measured, 1858 unique (R = 0.0585) which
int
were used in all calculations. The final wR (F2) was
0.0730 (all data). The data were measured using a
Stoe Image Plate Diffraction system equipped with
a φ circle, using Mo Kα graphite monochromated
[16] Farrugia, L. J. J Appl Crystallogr 1997, 30, 565.