Design of reversible multi-electron redox systems using benzochalcogenophenes containing aryl and/or ferrocenyl fragments

Article abstract of DOI:10.1016/j.jorganchem.2006.08.049

2,3-Disubstituted benzo[b]thiophenes, 1,3-disubstituted benzo[c]thiophenes, and 1,3-disubstituted benzo[c]selenophene have been systematically and selectively synthesized from benzo[b]thiophene or phthaloyl dichloride as a starting material, respectively. Characterization of the molecules was performed by physical and spectroscopic means and X-ray crystallographic analyses. The cyclic voltammograms of the chalcogenophene derivatives containing aryl fragments showed well-defined reversible both anodic and cathodic steps derived from the unusually stable 5π chalcogenophene radical cations and 7π chalcogenophene radical anions. The cyclic voltammograms of the novel chalcogenophene derivatives containing ferrocenyl fragments showed a well-defined reversible cathodic step derived from the unusually stable 7π chalcogenophene radical anions and two distinct reversible anodic steps derived from ferrocenium cations separated from each other by a thiophene-heterocycle. The radical character of several novel 7π chalcogenophene radical anions was measured by ESR spectroscopy.

Full text of DOI:10.1016/j.jorganchem.2006.08.049

Journal of Organometallic Chemistry 692 (2007) 60–69
www.elsevier.com/locate/jorganchem
Design of reversible multi-electron redox systems using
benzochalcogenophenes containing aryl and/or ferrocenyl fragments
*
*
Satoshi Ogawa , Hiroki Muraoka, Kenji Kikuta, Fumihito Saito, Ryu Sato
Department of Chemical Engineering, Faculty of Engineering, Iwate University, 4-3-5 Ueda, Morioka 020-8551 Iwate, Japan
Received 28 February 2006; accepted 7 April 2006
Available online 30 August 2006
Abstract
2,3-Disubstituted benzo[b]thiophenes, 1,3-disubstituted benzo[c]thiophenes, and 1,3-disubstituted benzo[c]selenophene have been sys-
tematically and selectively synthesized from benzo[b]thiophene or phthaloyl dichloride as a starting material, respectively. Characteriza-
tion of the molecules was performed by physical and spectroscopic means and X-ray crystallographic analyses. The cyclic
voltammograms of the chalcogenophene derivatives containing aryl fragments showed well-defined reversible both anodic and cathodic
steps derived from the unusually stable 5p chalcogenophene radical cations and 7p chalcogenophene radical anions. The cyclic voltam-
mograms of the novel chalcogenophene derivatives containing ferrocenyl fragments showed a well-defined reversible cathodic step
derived from the unusually stable 7p chalcogenophene radical anions and two distinct reversible anodic steps derived from ferrocenium
cations separated from each other by a thiophene-heterocycle. The radical character of several novel 7p chalcogenophene radical anions
was measured by ESR spectroscopy.
ꢀ 2006 Elsevier B.V. All rights reserved.
Keywords: Thiophene; Selenophene; Ferrocene; Radical cation; Radical anion; Redox reaction
1. Introduction
the design of reversible multi-steps redox systems using
simple molecules with both organic and organometallic
electron transfer fragments. Although the synthesis and
characterization of substituted benzochalcogenophenes
have been reported [4], there is no report concerning benz-
annulated thiophene and selenophene containing a ferro-
cene fragment on the five-membered heterocyclic unit,
which are of structural and redox-characteristic interest.
Recently, we reported a new type of multi-steps reversible
redox systems using organic–organometallic hybrid mole-
cules, 1-ferrocenyl- and 1,9-diferrocenyl-thianthrenes [5].
Therefore, we have designed 2,3-disubstituted benzo[b]thi-
ophene and 1,3-disubstituted benzo[c]chalcogenophene as
both cathodic and anodic multiple-redox active organic–
organometallic hybrid molecules. In this paper, we provide
the details on the synthesis, structural characterization, and
electrochemical properties of 2,3-disubstituted benzo[b]thi-
ophenes, 1,3-disubstituted benzo[c]thiophenes, and 1,3-
disubstituted benzo[c]selenophenes.
In recent years, the study of molecules comprising multi-
ple reduction–oxidation (redox) centers have attracted con-
siderable research interest in the field of material science
due to the preparation of new p-conjugated materials with
application in material science [1]. Moreover, this kind of
molecule having more than two redox-active metal centers
is a fundamentally attractive target for the study of multi-
electron transfer processes via the mixed-valence state
derived from these multi-metallic systems [2]. On the other
hand, interest in the design of novel redox-active organic
centers by the use of a 5p- and 7p-electron framework [3]
containing group 16 elements has led us to explore the syn-
thesis of new five-membered heterocycles containing sulfur
and/or selenium atom(s). This time our studies are aimed at
*
Corresponding authors. Tel./fax.: +81 19 621 6934.
E-mail address: ogawa@iwate-u.ac.jp (S. Ogawa).
0022-328X/$ - see front matter ꢀ 2006 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2006.08.049

S. Ogawa et al. / Journal of Organometallic Chemistry 692 (2007) 60–69
61
2. Results and discussion
was obtained in moderate yield. Then, compound 1 was
reacted with arylboronic acids by Suzuki-coupling [8] in
the presence of a catalytic amount of (PPh3)4Pd in dimeth-
ylformamide (DMF) at 100 ꢁC to give 3-aryl-2-ferro-
cenylbenzo[b]thiophene (2a–c) in good yields. The
synthesis of 2,3-diferrocenylbenzo[b]thiophene (2d) was
achieved through a single step transition metal-catalyzed
cross-coupling reaction of 1 with ferrocenylzinc chloride
in the presence of a catalytic amount of bis(triphenylpho-
phine)palladium(II) dichloride (PPh3)2PdCl2, in tetrahy-
drofuran (THF) under reflux condition in moderate yield
(Scheme 1).
2.1. Synthesis of 2,3-disubstituted benzo[b]thiophenes (2a–
d)
Upon treatment of 2,3-dibromobenzo[b]thiophene,
which was prepared by general bromination of benzo[b]thi-
ophene with bromine [6], with ferrocenylzinc chloride in
the presence of a catalytic amount of tetrakis(triphenylpho-
phine)palladium (PPh3)4Pd, in tetrahydrofuran (THF)
under reflux condition by the modified methods previously
reported [7] 3-bromo-2-ferrocenylbenzo[b]thiophene (1)
Scheme 1.
Scheme 2.

62
S. Ogawa et al. / Journal of Organometallic Chemistry 692 (2007) 60–69
2.2. Synthesis of 1,3-disubstituted benzo[c]thiophenes
(4a–d), and benzo[c]selenophenes (5)
We employed phthaloyl dichloride as a starting material
for the synthesis of 1,3-disubstituted benzo[c]thiophene
(4a–d). However, two acid chlorides in the ortho position
are too reactive toward nucleophilic substitution by the
use of Grignard or organolithium reagents even at low tem-
perature. Therefore, we synthesized 1,2-di[S-(2-pyridi-
nyl)]benzenedithioate which has two functional groups
with lower reactivity as compared with phthaloyl dichlo-
ride by the modified method previously reported [9]. Since
we obtained 1,2-di[S-(2-pyridinyl)]benzenedithioate, the
next step consisted of performing the reaction with aryl
Grignard reagents or a ferrocenyllithium reagent. The aryl
Grignard reagents were slowly added at 0 ꢁC to 1,2-di[S-(2-
pyridinyl)]benzenedithioate in a solution of THF. The mix-
ture was stirred at 0 ꢁC for 15 min and finally quenched by
addition of 2 mol dmꢀ3 HCl aqueous solution. After usual
work-up ortho diaroylbenzenes (3a–c) were obtained in
moderate yield. In the case of introduction of a ferrocenyl
substituent, the ferrocenyllithium, which was prepared
from ferrocene with t-butyllithium, was slowly added at
ꢀ60 ꢁC to 1,2-di[S-(2-pyridinyl)]benzenedithioate in a solu-
tion of THF. The mixture was stirred at ꢀ60 ꢁC for 30 min
and finally quenched by addition of HCl aqueous solution
(2 mol dmꢀ3). After usual work-up ortho diferrocenoylben-
zene (3d) was obtained in moderate yield. Finally, the isot-
hianaphthene core was formed through ring closure of 3a–
d by means of Lawesson’s reagent to give 1,3-disubstituted
benzo[c]thiophene (4a–d) in moderate yield (Scheme 2). In
the case of the synthesis of 1,3-diferrocenylbenzo[c]selen-
ophene (5) the final ring-closure reaction was performed
by the use of bis(dimethylaluminium) selenide developed
by Segi and Zingaro [10] as a selenating reagent.
Fig. 1. ORTEP drawing of (a) 2d Æ CH2Cl2 (dichloromethane molecule is
omitted for clarity), (b) 4d, and (c) 5. Thermal ellipsoids are drawn at 50%
probability.
3. X-ray crystallographic analysis
The molecular structures of benzo[b]thiophene 2d,
benzo[c]thiophene 4d, and benzo[c]selenophene 5 were
confirmed by X-ray crystallographic analyses (Fig. 1 and
Table 1). The data revealed that two ferrocene fragments
were located in anti-conformation, respectively, having
the dihedral angles between the chalcogenophene ring
and the bonded cyclopentadienyl ring of 34.3(5)ꢁ and
42.3(4)ꢁ for 2d, ꢀ23.7(2)ꢁ and +30.0(2)ꢁ for 4d, ꢀ21.9(5)ꢁ
and +30.1(5)ꢁ for 5. The anti-geometry of two fragments
in 2d implies the presence of repulsion of each bulky
substituent. On the other hand, the anti-geometry of 4d
and 5 could be explained by the crystal packing. The C–
C bond distances between the ferrocenyl carbon and the
the chalcogenophene ring and the cyclopentadienyl ring
of the ferrocene because the bond lengths were significantly
shorter than that of the sp –sp single bond (1.516 A) [13].
2
2
˚
4. Electrochemical studies
The solution redox properties of the benzochalcogen-
ophenes 2a–d, 4a–d, and 5 were studied by cyclic volmam-
metry technique, since little has been known about the
electrochemically stepwise multi-electron transfer behavior
of organic–organometallic hybrid molecules by the use of a
chalcogenophene framework as an organic redox unit. The
data are collected in Table 2 and typical cyclic voltammo-
grams (CV) of 2d, 4d, and 5 are shown in Fig. 2.
˚
carbon(s) next to the chalcogen atom are 1.458(4) A for
˚
2d, 1.461(2) and 1.461(2) A for 4d, 1.451(6) and
1.447(5) A for 5 and are similar to the corresponding bond
The CV of 2a–c at concentrations 2.0 mmol dmꢀ3 in
THF/0.1 mol dmꢀ3 n-Bu4NPF6 showed reversible oxida-
tion couples, E1/2 = +0.28 V for 2a; +0.27 V for 2b;
+0.28 V for 2c; vs. Ag/Ag+, derived from the formation
˚
˚
distance (1.464(7) A) of 2,5-diferrocenylthiophene previ-
ously reported [11]. These results suggest a double bond
character reflected a conjugation effect [4h,12] between

S. Ogawa et al. / Journal of Organometallic Chemistry 692 (2007) 60–69
63
Table 1
Selected bond lengths (A), bond angles (ꢁ), and torsion angles (ꢁ)
˚
Benzo[b]thiophene 2d
Benzo[c]thiophene 4d
Benzo[c]selenophene 5
Bond lengths
S1–C2
C2–C3
C3–C4
C4–C5
C5–S1
1.760(4)
1.355(4)
1.451(5)
1.404(5)
1.735(3)
1.458(4)
1.490(5)
S1–C2
C2–C3
C3–C4
C4–C5
C5–S1
C2–C6
C5–C8
1.720(2)
1.393(2)
1.443(2)
1.390(2)
1.714(2)
1.461(2)
1.461(2)
Se1–C2
C2–C3
C3–C4
C4–C5
C5–Se1
C2–C6
C5–C8
1.867(4)
1.381(5)
1.456(5)
1.386(5)
1.862(4)
1.447(5)
1.451(6)
C2–C6
C3–C8
Bond angles
S1–C2–C3
C2–C3–C4
C3–C4–C5
C4–C5–S1
C5–S1–C2
C8–C3–C2
C6–C2–C3
112.5(3)
S1–C2–C3
C2–C3–C4
C3–C4–C5
C4–C5–S1
C5–S1–C2
110.2(1)
Se1–C2–C3
C2–C3–C4
C3–C4–C5
C4–C5–Se1
C5–Se1–C2
109.9(3)
113.0(3)
111.3(2)
112.2(2)
91.0(2)
122.3(3)
130.3(3)
112.4(2)
112.9(1)
110.3(1)
94.16(8)
115.3(3)
115.0(3)
110.0(3)
89.8(2)
Torsion angles
C7–C6–C2–C3
C2–C3–C8–C9
C6–C2–C3–C8
34.3(5)
42.3(4)
4.8(5)
S1–C2–C6–C7
C9–C8–C5–S1
ꢀ23.7(2)
C9–C8–C5–Se1
Se1–C2–C6–C7
ꢀ21.9(5)
30.0(2)
30.1(5)
Table 2
Redox potentials [V vs. Ag/Ag+]a
Neutral/7p radical anion
Ferrocene/ferrocenium cation
First
Neutral/5p radical cation
Second
Epa
Epc
E1/2
Epa
Epc
E1/2
Epa
Epc
E1/2
Epa
Epc
E1/2
Benzo[b]thiophene
2a
2b
2cc
2d
ꢀ2.70b
ꢀ2.71
–
ꢀ2.71
ꢀ2.92b
ꢀ2.94
–
ꢀ3.02
–
+0.38
+0.38
+0.37
+0.38
+0.17
+0.16
+0.18
+0.06
+0.28
+0.27
+0.28
+0.22
ꢀ2.83
–
ꢀ2.87
+0.56
+0.25
+0.41
Benzo[c]thiophene
4a
4b
4c
4d
ꢀ2.06
ꢀ2.30
ꢀ1.77
ꢀ2.31
ꢀ2.25
ꢀ2.11
ꢀ1.93
ꢀ2.45
ꢀ2.16
ꢀ2.21
ꢀ1.85
ꢀ2.38
+0.93
+0.80
+1.10
+0.74
+0.63
+0.94
+0.84
+0.72
+1.02
+0.21
+0.27
+0.07
+0.02
+0.14
+0.15
+0.41
+0.51
+0.27
+0.26
+0.34
+0.39
Benzo[c]selenophene
ꢀ2.19
5
ꢀ2.42
ꢀ2.31
a
Conditions: concentration, 2 mmol dmꢀ3 sample in 0.1 mol dmꢀ3 n-Bu4NPF6/THF solution; working electrode, glassy-carbon; reference electrode,
Ag/0.01 mol dmꢀ3 AgNO3 in 0.1 mol dmꢀ3 n-Bu4NPF6/CH3CN solution; counter electrode, Pt; temperature, 223–233 K for 2a–d, 293 K for 4a–d, 233 K
for 5; scan rate, 200 mV sꢀ1 for 2a–d, 100 mV sꢀ1 for 4a–d and 5.
b
Quasi-reversible.
Reduction peak was not observed.
c
of the ferrocenium cation. At negative scan, one-electron
reduction waves derived from 7p thiophene radical anions
were observed, Epc = ꢀ2.92 V for 2a;ꢀ2.94 V for 2b. The
reduction wave involving decomposition for 2c was
observed in this condition, but the clear reduction peak
could not be assigned. Interestingly, the reduction poten-
tials for 2a and 2b were almost the same, while the electro-
chemical reversibility was different; quasi-reversible for 2a;
reversible for 2b. Therefore, although aryl substituents of
the 3-position of the benzo[b]thiophene framework serve
for stability of the 7p thiophene radical anions, those have
little influence on the reduction potential of the thiophene
moiety and oxidation potential of the ferrocene moiety.
The CV of 4a–c under the same conditions showed well-
defined reversible two one-electron redox couples, E1/
2 = ꢀ2.16, +0.84 V for 4a; ꢀ 2.21, +0.72 V for 4b; ꢀ 1.85,
+1.02 V for 4c; derived from the formation of the 7p thio-
phene radical anions and 5p thiophene radical cations. The
oxidation and reduction half-potentials indicate that the
HOMO level elevates in the order of 4c < 4a < 4b, and
the LUMO level elevates in the order of 4b > 4a > 4c.
These results indicate that electron-donating or -withdraw-

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S. Ogawa et al. / Journal of Organometallic Chemistry 692 (2007) 60–69
scan, the reduction of 2d, 4d, and 5 is chemically reversible
and a cathodic product wave appears, assigned to forma-
tion of the corresponding 7p chalcogenophene radical
anions. On the other hand, at positive scan, the oxidation
of 2d, 4d, and 5 is also chemically reversible and two anodic
product waves appear, assigned to stepwise formation of
the corresponding mono- and bis-(ferrocenium cation).
By CV and differential pulse voltammograms (DPV)
measurements of 2d, 4d, and 5 employing dichloromethane
(CH2Cl2) as a solvent, the oxidation waves derived from
the ferrocene fragments showed good separated and well-
defined reversible one-electron redox couples (Fig. 3 and
Table 3). These results suggest that the dielectric constant
of the solvent has a significant effect on the electrostatic
contributions to the two oxidation processes of the intra-
molecular ferrocene fragments [14]. The differences
between the first and second half-potentials ðDE1=2
¼
E11=2 ꢀ E21=2Þ for the Fe(II)–Fe(III) and Fe(III)–Fe(III) cou-
ples of 2d, 4d, and 5 were 192, 280, and 305 mV, respec-
tively (Table 3). These results suggest that the structural
difference between diferrocenylbenzothiophene 2d and 4d
based on the annulation mode and the substituent position
should cause the differences in their redox behavior and
thermodynamic stability in mixed-valence intermediates.
The comproportionation constants (Kc) [15] for the
Fe(II)–Fe(III) mixed-valence state estimated from DE1/2
were 1.1 · 105 for 4d and 3.0 · 105 for 5. Therefore, the
electronic interaction between the metal center of ferrocene
and the ferrocenium cation in the mixed-valence state of 4d
Fig. 2. Cyclic voltammograms of (a) 2d, (b) 4d, and (c) 5 in THF
(0.1 mol dmꢀ3 n-Bu4NPF6). The measurements were carried out at 223 K
Table 3
for 2d, 293 K for 4d, 233 K for 5 with scan rate 100–200 mV sꢀ1
.
Redox potentials [V vs. Ag/Ag+]a
b
E11=2 (V)
E21=2 (V)
DE1/2 (mV)
2d
4d
5
+0.21
+0.13
+0.12
+0.40
+0.41
+0.42
+192
+280
+305
ing effects of the aryl groups at 1,3-positions influence both
the reduction and oxidation potentials.
On the other hand, the dominant feature of CV scans of
benzochalcogenophenes containing two ferrocene units at
the same conditions is three one-electron redox couples,
E1/2 = ꢀ2.87, +0.22, +0.41 V for 2d; ꢀ 2.38, +0.14,
+0.34 V for 4d; ꢀ2.31, +0.15, +0.39 V for 5; vs. Ag/Ag+,
respectively, that is well-defined reversibility. At negative
a
Conditions: concentration, 1 mmol dmꢀ3 sample in 0.1 mol dmꢀ3 n-
Bu4NPF6/CH2Cl2 solution; temperature, 281 K; working electrode,
glassy-carbon; reference electrode, Ag/0.01 mol dmꢀ3 AgNO3 in
0.1 mol dmꢀ3 n-Bu4NPF6/CH3CN solution; counter electrode, Pt; scan
rate, 100 mV sꢀ1
b
.
DE1=2 ¼ E21=2 ꢀ E11=2
.
Fig. 3. Cyclic (top) and differential pulse (bottom) voltammograms of (a) 1, (b) 2 and (c) 3 in CH2Cl2 (0.1 mol dmꢀ3 n-Bu4NPF6). The measurements were
carried out at 281 K with scan rate 100 mV sꢀ1
.

S. Ogawa et al. / Journal of Organometallic Chemistry 692 (2007) 60–69
65
Fig. 4. ESR spectra of (a) 2dÅꢀ, (b) 4dÅꢀ, and (c) 5Åꢀin THF.
and 5 can be expected to be strong because of potential
through-bond and/or through-space interactions. In the
case of compound 2d, it is difficult to discuss the compro-
portionation constant Kc, because it has essentially differ-
ent oxidation potential based on the position of ferrocenes.
form-d as a solvent with Me4Si as the internal standard.
77Se (76 MHz) NMR spectra used Me2Se as the external
standard. IR spectra were recorded on a JASCO FT-7300
spectrometer. Mass spectra were determined on a Hitach
M-2000 spectrometer operating at 70 eV in the EI mode.
Elemental analyses were carried out by using a Yanagim-
oto MT-5 CHN corder and determined in the Division of
Elemental Analysis in Iwate University. Cyclic voltamme-
try was carried out by using a Cypress Systems CS-1090
galvanostat/potentiostat or a Hokuto Denko function gen-
erator HB-104 and galvanostat/potentiostat HA-303. A
three-electrode system was used, consisting of a glassy-car-
bon working electrode, a platinum wire auxiliary electrode
and an Ag/0.01 mol dmꢀ3 AgNO3 reference electrode. The
measurements were carried out in THF or dichlorometh-
ane solution containing 0.1 mol dmꢀ3 n-Bu4NPF6 as a
supporting electrolyte with scan rates in a range of
100–200 mV sꢀ1 under an Ar atmosphere. ESR data were
taken in a JEOL JES-FA 100 spectrometer working in the
X-band as THF solution with Mn2+ on MgO as field mar-
ker. All solvents used in the reactions were purified by the
general methods. All reactions were carried out under a
nitrogen or an argon atmosphere. Silica-gel column chro-
matography was performed with a Wakogel C-200.
5. 7p Radical anions and ESR spectra
In contrast to the studies on oxidation of chalcogenoph-
enes [16], there are few reports for the formation of 7p chal-
cogenophene radical anions [16a,16d,16f,17] by reduction.
The results of the reversibility observed in CV described
above clearly indicate that the several benzochalcogenoph-
enes generate stable 7p radical anions even at room temper-
ature. Several novel benzochalcogenophene radical anions,
2dÅꢀ, 4dÅꢀ, and 5Åꢀ, were readily generated in the one-elec-
tron reduction of benzochalcogenophenes, 2d, 4d, and 5, in
THF with metal potassium under an argon atmosphere.
The ESR spectra of the dark blue or green solution of
showed the presence of broad singlet peaks, g = 2.00474
for 2dÅꢀ; 2.00895 for 4dÅꢀ; 2.01343 for 5Åꢀ; attributable to
the corresponding 7p radical anions (Fig. 4). Unfortu-
nately, hyper-fine splitting of each radical anion could
not be observed under our measurement conditions.
6. Conclusions
7.2. Synthesis of 3-bromo-2-ferrocenylbenzo[b]thiophene
(1)
We have synthesized and characterized novel benzochal-
cogenophenes containing aryl and/or ferrocenyl units. The
electrochemical properties showed reversible multi-electron
transfer phenomena assigned to the chalcogenophene
(organic) and ferrocene (organometallic) fragments owing
to good stability of the negative-charged reduction prod-
ucts (radical anions) and positive-charged oxidation prod-
ucts (radical cations, and mono- or bis-ferrocenium
cations). Therefore, we succeeded in establishing a new
type of multi-steps reversible redox systems using neutral
organic–organometallic hybrid molecules.
To a stirred solution of ferrocene (1.552 g, 8.342 mmol)
in THF (10 mL) was added t-butyllithium (5.5 mL of a
1.53 M pentane solution, 8.3 mmol) at 0 ꢁC under an N2
atmosphere. After stirring at 0 ꢁC for 1 h, a solution of zinc
chloride (1.137 g, 8.343 mmol) in THF (20 mL) was added
to the mixture, and the resulting mixture stirred at room
temperature for 2 h. To the mixture was added a solution
of 2,3-dibromobenzo[b]thiophene (1.740 g, 5.959 mmol)
and
tetrakis(triphenylphosphine)palladium
(0.413 g,
0.358 mmol) in THF (20 mL). After stirring under reflux
for 24 h, it was cooled to room temperature. The reaction
mixture was acidified with aqueous hydrochloric acid,
and extracted with chloroform. The organic layer was dried
over anhydrous magnesium sulfate and the solvent was
evaporated under reduced pressure. The residue was
purified by column chromatography (silica gel, hexane) to
give 3-bromo-2-ferrocenylbenzo[b]thiophene (1, 1.164 g,
7. Experimental
7.1. General
Melting and decomposition points were determined on a
Mel-Temp capillary tube apparatus, and were uncorrected.
1H (400 MHz) and 13C (101 MHz) NMR spectra were
measured on a Bruker AC-400 spectrometer using chloro-
1
2.932 mmol, 49%): orange plate; mp 125.5–126.6 ꢁC; H
NMR (400 MHz, CDCl3) d 4.19 (s, 5H, free-Cp), 4.41 (t,

66
S. Ogawa et al. / Journal of Organometallic Chemistry 692 (2007) 60–69
J = 1.9 Hz, 2H, C5H4), 4.99 (t, J = 1.9 Hz, 2H, C5H4), 7.34
(td, J = 0.8, 8.0 Hz, 1H, ArH), 7.41 (td, J = 0.8, 8.0 Hz,
1H, ArH), 7.72 (d, J = 8.0 Hz, 1H, ArH), 7.76 (dd,
J = 0.8, 8.0 Hz, 1H, ArH); 13C NMR (101 MHz, CDCl3)
d 69.3 (2C), 70.1, 77.6, 103.4, 121.8, 122.6, 124.9, 125.1,
136.7, 138.5, 139.5; IR (KBr) m 3457, 3094, 1542, 1445,
1422, 1258, 1000, 808, 493 cmꢀ1; MS (70 eV) m/z 398
(M+); Anal. Calc. for C18H13BrFeS: C, 54.44; H, 3.30.
Found: C, 54.58; H, 3.30%.
2H, C5H4), 4.219 (br t, 2H, C5H4), 7.27–7.35 (m, 3H,
ArH), 7.48 (d, J = 8.0 Hz, 2H, ArH), 7.73 (d, J = 8.0 Hz,
2H, ArH), 7.80 (d, J = 7.6 Hz, ArH); 13C NMR
(101 MHz, CDCl3) d 69.1, 69.3, 70.2, 78.4, 121.9, 122.1,
124.28, 124.34 (q, J13 C-19F = 272.2 Hz), 124.6, 125.6 (q,
J13C–19F = 3.6 Hz), 129.8 (q, J13C–19F = 32.2 Hz), 130.7,
130.8, 138.3, 140.3, 140.7, 140.9; IR (KBr) m 3059, 1930,
1616, 1403, 1067, 918, 840, 765, 622 cmꢀ1; MS (70 eV) m/
z 462 (M+); Anal. Calc. for C25H17F3FeS: C, 64.95; H,
3.71. Found: C, 64.71; H, 4.04%.
7.3. General procedure for the synthesis of 3-aryl-2-
ferrocenylbenzo[b]thiophene (2a–2c)
7.6. Synthesis of 2,3-diferrocenylbenzo[b]thiophene (2d)
A solution of 3-bromo-2-ferrocenylbenzo[b]thiophene
(1, 0.397 g, 1.000 mmol), phenylboronic acid (0.134 g,
1.10 mmol), cesium carbonate (0.492 g, 1.51 mmol), and
tetrakis(triphenylphosphine)palladium (0.023 g, 0.020
mmol) in DMF (12 mL)/water (2 mL) was stirred for
24 h at 100 ꢁC under an N2 atmosphere. After cooling to
room temperature, the reaction mixture was acidified with
aqueous hydrochloric acid, and extracted with chloroform.
The organic layer was dried over anhydrous magnesium
sulfate and the solvent was evaporated under reduced pres-
sure. The residue was purified by column chromatography
(silica gel, chloroform:hexane = 1:4) to give 2-ferrocenyl-3-
phenylbenzo[b]thiophene (2a, 0.346 g, 0.877 mmol, 88%):
brown plate; mp 161.2–161.9 ꢁC; 1H NMR (400 MHz,
CDCl3) d 4.08 (s, 5H, free-Cp), 4.18 (t, J = 1.9 Hz, 2H,
C5H4), 4.23 (t, J = 1.9 Hz, 2H, C5H4), 7.22–7.36 (m, 5H,
ArH), 7.40–7.49 (m, 3H, ArH), 7.78 (d, J = 7.3 Hz, 1H,
ArH); 13C NMR (101 MHz, CDCl3) d 68.8, 69.0, 70.0,
78.8, 121.7, 122.4, 123.9, 124.3, 127.5, 128.6, 130.3, 132.2,
136.2, 138.1, 139.4, 141.5; IR (KBr) m 3062, 1425, 1055,
1001, 812, 758, 730, 609, 497 cmꢀ1, MS (70 eV) m/z 394
(M+); Anal. Calc. for C24H18FeS: C, 73.10; H, 4.60.
Found: C, 72.96; H, 4.84%.
To a stirred solution of ferrocene (2.989 g, 16.07 mmol)
in THF (20 mL) was added t-butyllithium (11.0 mL of a
1.45 M pentane solution, 16.0 mmol) at 0 ꢁC under an Ar
atmosphere. After stirring at 0 ꢁC for 1 h, a solution of zinc
chloride (2.177 g, 15.97 mmol) in THF (30 mL) was added
to the mixture, and the resulting mixture was stirred at
room temperature for 2 h. To the mixture was added a
solution of 2,3-dibromobenzo[b]thiophene (1.177 g, 4.031
mmol) and bis(triphenylphosphine)palladium dichloride
(0.168 g, 0.239 mmol) in THF (30 mL). After stirring under
reflux for 18 h, it was cooled to room temperature. The
reaction mixture was acidified with aqueous hydrochloric
acid, and extracted with chloroform. The organic layer
was dried over anhydrous magnesium sulfate and the sol-
vent was evaporated under reduced pressure. The residue
was purified by column chromatography (silica gel, hexane,
and then chloroform:hexane = 1:5) to give 2,3-difer-
rocenylbenzo[b]thiophene (2d, 0.825 g, 1.64 mmol, 58%):
1
brown crystals; mp 175.9–176.3 ꢁC; H NMR (400 MHz,
CDCl3) d 4.06 (s, 5H, free-Cp), 4.15 (s, 5H, free-Cp), 4.25
(t, J = 1.9 Hz, 2H, C5H4), 4.26 (t, J = 1.9 Hz, 2H, C5H4),
4.32 (t, J = 1.9 Hz, 2H, C5H4), 4.36 (t, J = 1.9 Hz, 2H,
C5H4), 7.35 (td, J = 1.3, 8.0 Hz, 1H, ArH), 7.44 (td,
J = 1.3, 8.0 Hz, 1H, ArH), 7.78 (d, J = 8.0 Hz, 1H, ArH),
8.57 (d, J = 8.0 Hz, 1H, ArH); 13C NMR (101 MHz,
CDCl3) d 68.3, 68.1, 69.2, 69.6, 70.0, 70.6, 80.5, 80.8,
121.7, 123.5, 123.8, 124.1, 128.9, 138.7, 138.9, 140.0; IR
(KBr) m 3100, 2362, 1412, 1320, 1107, 1000, 820, 733,
490 cmꢀ1; MS (70 eV) m/z 502 (M+); Anal. Calc. for
C28H22Fe2S: C, 66.96; H, 4.42. Found: C, 67.28; H, 4.65%.
7.4. 2-Ferrocenyl-3-(p-methoxyphenyl)benzo[b]thiophene
(2b)
Dark brown plate; mp 185.2–186.0 ꢁC; 1H NMR
(400 MHz, CDCl3) d 4.08 (s, 5H, free-Cp), 4.19 (t,
J = 1.9 Hz, 2H, C5H4), 4.26 (t, J = 1.9 Hz, 2H, C5H4),
7.01 (d, J = 8.6 Hz, 2H, ArH), 7.23–7.35 (m, 5H, ArH),
7.76–7.78 (m, 1H, ArH); 13C NMR (101 MHz, CDCl3) d
55.3, 68.7, 69.0, 70.0, 78.9, 114.0, 121.7, 122.4, 123.9,
124.2, 128.3, 131.4, 131.8, 138.0, 139.2, 141.7, 159.0; IR
(KBr) m 2833, 1609, 1508, 1456, 1286, 1242, 1105, 1032,
820, 763, 578, 532, 496 cmꢀ1; MS (70 eV) m/z 424 (M+);
Anal. Calc. for C25H20FeOS: C, 70.76; H, 4.75. Found:
C, 70.68; H, 4.80%.
7.7. Synthesis of 1,2-di[S-(pyridinyl)]benzenedithioate
To a stirred solution of 2-mercaptopyridine (1.1 g,
9.9 mmol) in THF (20 mL) was added triethylamine
(1.67 mL) at 0 ꢁC under an N2 atmosphere. After stirring
for 15 min at 0 ꢁC, phthaloylchloride (0.73 mL, 5.1 mmol)
was added to the mixture. Immediately the reaction was
quenched by the addition of aqueous hydrochloric acid.
After the resulting mixture was extracted with dichloro-
methane, the organic layer was washed with saturated
sodium hydrogencarbonate solution and dried over anhy-
drous magnesium sulfate. The solvent was evaporated
under reduced pressure, and the residue was purified by
7.5. 2-Ferrocenyl-3-(p-trifluoromethylphenyl)benzo[b]-
thiophene (2c)
Dark brown plate; mp 239.1–240.7 ꢁC; 1H NMR
(400 MHz, CDCl3) d 4.11 (s, 5H, free-Cp), 4.216 (br t,

S. Ogawa et al. / Journal of Organometallic Chemistry 692 (2007) 60–69
67
recrystallization from dichloromethane/ether to give 1,2-
di[S-(pyridinyl)]benzenedithioate (1.476 g, 4.188 mmol,
83%): colorless crystals; mp 114.3–115.1 ꢁC (lit. [9b],
109.7 ꢁC); 1H NMR (400 MHz, CDCl3) d 7.30 (t,
J = 5.7 Hz, ArH), 7.65 (dd, J = 3.4, 5.6 Hz, 2H, ArH),
7.31–7.79 (m, 4H, ArH), 7.88 (dd, J = 3.4, 5.6 Hz, 2H,
ArH), 8.63 (d, J = 4.8 Hz, 2H, ArH); 13C NMR
(101 MHz, CDCl3) d 123.7, 128.5, 130.4, 132.0, 136.7,
137.3, 150.3, 151.2, 190.1.
in chloroform (30 mL) was stirred under reflux for 12 h.
After the solvent was evaporated under reduced pressure,
the residue was dissolved in ethanol (30 mL) and the mix-
ture was stirred under reflux for 12 h. After the resulting
solution was cooled to room temperature, the solvent was
evaporated under reduced pressure. The residue was dis-
solved in chloroform and was washed with sodium hydrox-
ide solution (1 mol dmꢀ3). The organic layer was dried over
anhydrous magnesium sulfate and the solvent was evapo-
rated under reduced pressure. The residue was purified by
column chromatography (silica gel, chloroform:hexane =
1:1) to give 1,3-diphenylbenzo[c]thiophene (4a, 0.191 g,
0.667 mmol, 67%): yellow crystals; mp 117.6–117.9 ꢁC
(lit. [4d], 117–119 ꢁC); 1H NMR (400 MHz, CDCl3) d
7.09 (dd, J = 3.0, 6.9 Hz, 2H, ArH), 7.38 (t, J = 7.6 Hz,
2H, ArH), 7.51 (t, J = 7.6 Hz, 4H, ArH), 7.69 (d,
J = 7.6 Hz, 4H, ArH), 7.83 (dd, J = 3.0, 6.9 Hz, 2H, ArH).
7.8. General procedure for the synthesis of o-aroylbenzene
(3a–3c)
A solution of bromobenzene (4.003 g, 25.49 mmol) in
THF (20 mL) was added to activated magnesium (0.744 g,
30.5 mmol) in THF (20 mL). After stirring for 3.5 h at room
temperature, the solution was added to a solution of 1,2-
di[S-(pyridinyl)]benzenedithioate (4.492 g, 12.75 mmol) in
THF (70 mL) at 0 ꢁC. After the mixture was stirred for
15 min at 0 ꢁC under an N2 atmosphere, it was acidified with
aqueous hydrochloric acid (2 mol dmꢀ3). The resulting mix-
ture was extracted with ether. Then, the organic layer was
washed with aqueous sodium hydroxide (1 mol dmꢀ3), satu-
rated sodium hydrogencarbonate solution, and brine, and
dried over anhydrous magnesium sulfate. After the solvent
was evaporated under reduced pressure, the residue was
purified by column chromatography (silica gel, ethyl ace-
tate:hexane = 1:5) to give o-dibenzoyllbenzene (3a, 2.431 g,
8.49 mmol, 67%): pale yellow crystals; mp 147.0–147.6 ꢁC
7.12. 1,3-Bis(p-methoxyphenyl)benzo[c]thiophene (4b)
Yellow crystals; mp 143.1–144.2 ꢁC (lit. [4d], 140–
142 ꢁC); 1H NMR (400 MHz, CDCl3) d 3.88 (s, 6H,
OCH3), 7.03 (d, J = 8.8 Hz, 4H, ArH), 7.04–7.06 (m, 2H,
ArH), 7.60 (d, J = 8.8 Hz, 2H, ArH), 7.76 (dd, J = 3.1,
6.9 Hz, 2H, ArH), 13C NMR (101 MHz, CDCl3) d 55.4,
114.4, 121.1, 123.8, 126.8, 130.3, 133.1, 134.7, 159.1; IR
(KBr) m 3061, 1921, 1614, 1324, 1166, 1014, 755, 635,
443 cmꢀ1; MS (70 eV) m/z 346 (M+); Anal. Calc. for
C22H18O2S: C, 76.27; H, 5.24. Found: C, 76.19; H, 5.27%.
1
(lit. [4d], 144–148 ꢁC); H NMR (400 MHz, CDCl3) d 7.36
(t, J = 7.5 Hz, 4H, ArH), 7.51 (t, J = 7.5 Hz, 2H, ArH),
7.13. 1,3-Bis(p-trifluoromethylphenyl)benzo[c]thiophene
(4c)
7.61 (s, 4H, ArH), 7.69–7.71 (m, 4H, ArH).
7.9. o-Bis(p-methoxyphenoyl)benzene (3b)
Yellow crystals; mp 147.6–148.2 ꢁC; 1H NMR
(400 MHz, CDCl3) d 7.18 (dd, J = 3.0, 6.9 Hz, 2H, ArH),
7.76 (d, J = 8.5 Hz, 4H, ArH), 7.80 (d, J = 8.5 Hz, 4H,
ArH), 7.83 (dd, J = 3.0, 6.9 Hz, 2H, ArH), 13C NMR
Pale yellow crystals, mp 157.3–158.1 ꢁC (lit. [4d], 153–
156 ꢁC); 1H NMR (400 MHz, CDCl3) d 3.84 (s, 6H,
OCH3), 6.85 (d, J = 8.9 Hz, 4H, ArH), 7.58 (s, 4H, ArH),
7.67 (d, J = 8.9 Hz, 4H, ArH); 13C NMR (101 MHz,
CDCl3) d 55.4, 113.5, 129.2, 129.9, 130.2, 132.1, 140.1,
163.4, 195.3; IR (KBr) m 3069, 2838, 1655, 1596, 1510,
(101 MHz, CDCl3)
d
120.8, 124.1 (q, J13C–
19F = 272.0 Hz), 125.2, 126.1 (q, J13C–19F = 3.7 Hz), 129.3,
129.5 (q, J13C–19F = 32.7 Hz), 133.5, 135.9, 137.5; IR
(KBr) m 3061, 1614, 1408, 1325, 1165, 1113, 1068, 1014,
840, 600, 443 cmꢀ1; MS (70 eV) m/z 422 (M+); Anal. Calc.
for C22H12F6S: C, 62.56; H, 2.86. Found: C, 62.36; H,
3.21%.
1315, 1263, 1173, 1150, 1032, 937, 840, 753, 599 cmꢀ1
;
MS (70 eV) m/z 346 (M+); Anal. Calc. for C22H18O4: C,
76.29; H, 5.24. Found: C, 76.55; H, 5.28%.
7.10. o-Bis(p-trifluoromethylphenoyl)benzene (3c)
7.14. Synthesis of o-biferrocenoylbenzene (3d)
This compound was difficult to obtain as a completely
pure form by chromatographic technique. We employed
the compound as a mixture of crude yellow oil to the next
cyclization.
To a stirred solution of ferrocene (1.310 g, 7.041 mmol)
in THF (15 mL) was added t-butyllithium (4.03 mL of a
1.40 M pentane solution, 5.64 mmol) at 0 ꢁC under an N2
atmosphere. After the mixture was stirred at 0 ꢁC for 1 h,
it was cooled to ꢀ60 ꢁC. A solution of 1,2-di[S-(2-pyridi-
nyl)]benzenedithioate (0.500 g, 1.41 mmol) in THF
(10 mL) was added to the mixture, and the resulting mix-
ture was stirred at ꢀ60ꢁC for 30 min. The reaction mixture
was acidified with aqueous hydrochloric acid, and
extracted with ether. The organic layer was dried over
7.11. General procedure for the synthesis of 1,3-
diarylbenzo[c]thiophene (4a–4c)
A
mixture of o-dibenzoylbenzene (3a, 0.286 g,
0.999 mmol) and Lawesson’s reagent (0.808 g, 2.00 mmol)

68
S. Ogawa et al. / Journal of Organometallic Chemistry 692 (2007) 60–69
anhydrous magnesium sulfate and the solvent was evapo-
rated under reduced pressure. The residue was purified by
column chromatography (silica gel, ethyl acetate:hex-
ane = 1:4) to give o-diferrocenoylbenzene (3d, 0.322 g,
6.41 mmol, 46%): red crystals; mp > 300 ꢁC (decomp.);
1H NMR (400 MHz, CDCl3) d 4.21 (s, 10H, free-Cp),
4.48 (t, J = 1.9 Hz, 4H, C5H4), 4.68 (t, J = 1.9 Hz, 4H,
C5H4), 7.58 (dd, J = 3.3, 5.6 Hz, 2H, ArH), 7.83 (dd,
J = 3.3, 5.6 Hz, 2H, ArH); 13C NMR (101 MHz, CDCl3)
d 70.2, 71.0, 72.2, 79.2, 128.5, 129.7, 140.1, 200.1; IR
(KBr) m 3089, 1711, 1644, 1445, 1374, 1286, 1026, 828,
506 cmꢀ1; MS (70 eV) m/z 502 (M+); Anal. Calc. for
C28H22Fe2O2: C, 66.97; H, 4.42. Found: C, 67.01; H,
4.43%.
gel, chloroform:hexane = 1:1) to give 1,3-diferrocenyl-
benzo[c]selenophene (5, 0.414 g, 0.754 mmol, 75%): purple
crystals; mp 196.0 ꢁC (decomp.); 1H NMR (400 MHz,
CDCl3) d 4.19 (s, 10H, free-Cp), 4.39 (t, J = 1.8 Hz, 4H,
C5H4), 4.69 (t, J = 1.8 Hz, 4H, C5H4), 6.86 (dd, J = 3.1,
7.1 Hz, 2H, ArH), 7.67 (dd, J = 3.1, 7.1 Hz, 2H, ArH);
13C NMR (101 MHz, CDCl3) d 68.7, 69.2, 70.2, 82.4,
122.5, 122.7, 137.6, 139.6; 77Se NMR (76 MHz, CDCl3) d
687.8; IR (KBr) m 3090, 2346, 1655, 1410, 1314, 1104,
1000, 838, 819, 741, 478 cmꢀ1; MS (70 eV) m/z 550 (M+);
Anal. calcd for C28H22Fe2Se: C, 61.24, H, 4.04. Found:
C, 60.99, H, 4.34%.
7.17. X-ray crystal structure analyses of 2d, 4d, and 5
7.15. Synthesis of 1,3-diferrocenylbenzo[c]thiophene (4d)
Diffraction data were collected on a Rigaku R-AXIS
RAPID diffractometer employing Mo Ka (k = 0.71075 A)
˚
A mixture of o-diferrocenoylbenzene (3d, 0.629 g,
1.25 mmol) and Lawesson’s reagent (1.012 g, 2.505 mmol)
in dichloromethane (30 mL) was stirred for 12 h at room
temperature. After evaporation of the dichloromethane
under reduced pressure, the residue was dissolved in etha-
nol (30 mL) and the mixture was stirred under reflux for
12 h. After the resulting solution was cooled to room tem-
perature, the solvent was evaporated under reduced pres-
sure. The residue was dissolved in chloroform and was
washed with aqueous sodium hydroxide (1 mol dmꢀ3).
The organic layer was dried over anhydrous magnesium
sulfate and the solvent was evaporated under reduced pres-
sure. The residue was purified by column chromatography
(silica gel, chloroform:hexane = 1:1) and recrystallization
from hexane to give 1,3-diferrocenylbenzo[c]thiophene
(4d, 0.410 g, 0.816 mmol, 65%): purple crystals; mp
radiation. The structure was determined by direct methods
(SIR 92 [18] or 97 [19]) and expanded using Fourier technique
(DIRDIF99 [20]). All calculations were performed using the
Crystal Structure 3.5.1 or 3.6.0 crystal structure analysis
package of Rigaku and Rigaku/MSC.
Crystal data for 2d Æ CH2Cl2: M = 587.17, C29H24-
ꢀ
˚
˚
Fe2SCl2, triclinic, space group P1 (#2), a = 10.429(2) A,
˚
b = 11.043(2) A, c = 11.191(2) A, a = 83.94(2)ꢁ, b =
3
˚
68.99(2)ꢁ, c = 84.01(2)ꢁ, V = 1193.4(5) A , Z = 2, Dcalc
=
1.634 g cmꢀ3
,
T = 123 1 K, k(Mo Ka) = 0.71075 A,
˚
10,031 reflections measured, 4830 unique (Rint = 0.045).
The final cycle of full-matrix least-squares refinement was
based on 4405 observed reflections (I > 2.00r(I)) and 403
variable parameters with R1 = 0.046, wR2 = 0.112 (all
data).
Crystal data for 4d: M = 502.24, C28H22Fe2S, mono-
1
˚
196.0 ꢁC (decomp.); H NMR (400 MHz, CDCl3) d 4.18
clinic, space group P21/c (#14), a = 11.9107(8) A, b =
˚
˚
(s, 10H, free-Cp), 4.39 (t, J = 1.8 Hz, 4H, C5H4), 4.74 (t,
J = 1.8 Hz, 4H, C5H4), 7.00 (dd, J = 3.1, 6.9 Hz, 2H,
ArH), 7.81 (dd, J = 3.1, 6.9 Hz, 2H, ArH); 13C NMR
(101 MHz, CDCl3) d 68.4, 68.6, 69.9, 80.2, 121.9, 123.0,
130.7, 135.2; IR (KBr) m 3093, 2927, 1741, 1644, 1464,
804, 740 cmꢀ1; MS (70 eV) m/z 502 (M+); Anal. calcd for
C28H22Fe2S: C, 66.96, H, 4.42. Found: C, 66.80, H, 4.47%.
14.1854(8) A, c = 12.218(1) A, b = 92.359(3)ꢁ, V =
3
2062.6(3) A , Z = 4, Dcalc = 1.617 g cmꢀ3, T = 123 1 K,
˚
˚
k(Mo Ka) = 0.71075 A, 20,093 reflections measured, 4721
unique (Rint = 0.033). The final cycle of full-matrix least-
squares refinement was based on 4721 observed reflections
(I > 2.00r(I)) and 368 variable parameters with R1 = 0.025,
wR2 = 0.031 (all data).
Crystal data for 5: M = 549.14, C28H22Fe2Se, mono-
˚
7.16. Synthesis of 1,3-diferrocenylbenzo[c]selenophene
clinic, space group P21/a (#14), a = 12.139(4) A, b =
˚
˚
14.190(5) A,
c = 12.083(4) A,
b = 92.01(2)ꢁ,
V =
3
2080(1) A , Z = 4, Dcalc = 1.753 g cmꢀ3, T = 123 1 K,
k(Mo Ka) = 0.71075 A, 19,106 reflections measured, 4593
˚
To a stirred solution of bis(tributyltin) selenide (2.800 g,
4.248 mmol) in toluene (20 mL) was added trimethylalmin-
ium (8.1 mL of a 0.98 M THF solution, 7.9 mmol) at 0 ꢁC
under an N2 atmosphere. After the mixture was stirred at
50 ꢁC for 4 h, a solution of o-diferrocenoylbenzene (3d,
0.502 g, 1.00 mmol) in THF (70 mL) was added to the mix-
ture. After stirring at 50 ꢁC for 18 h, water was added. The
resulting mixture was extracted with ether. The organic
layer was washed with aqueous sodium hydroxide
(1 mol dmꢀ3) and saturated sodium hydrogencarbonate
solution. Then, it was dried over anhydrous magnesium
sulfate and the solvent evaporated under reduced pressure.
The residue was purified by column chromatography (silica
˚
unique (Rint = 0.089). The final cycle of full-matrix
least-squares refinement was based on 3783 observed reflec-
tions (I > 2.00r(I)) and 369 variable parameters with
R1 = 0.041, wR2 = 0.114 (all data).
Crystallographic data have been deposited with the
Cambridge Crystallographic Data Centre: Deposition
number CCDC-299170 for compound No. 2d, CCDC-
299169 for compound No. 4d, and CCDC-299168 for
compound No. 5. Copies of the data can be obtained free
of charge via http://www.ccdc.cam.ac.uk/conts/retriev-
ing.html (or from the Cambridge Crystallographic Data

S. Ogawa et al. / Journal of Organometallic Chemistry 692 (2007) 60–69
69
(o) A.K. Mohanakrishnan, P. Amaladass, Tetrahedron Lett. 46
(2005) 4225;
(p) A.K. Mohanakrishnan, P. Amaladass, Tetrahedron Lett. 46
(2005) 7201.
Centre, 12, Union Road, Cambridge, CB2 1EZ, UK; fax:
+44 1223 336033; e-mail: deposit@ccdc.cam.ac.uk).
Acknowledgements
[5] S. Ogawa, H. Muraoka, R. Sato, Tetrahedron Lett. 47 (2006)
2479.
[6] A. Heynderickx, A. Samat, R. Guglielmetti, Synthesis 2 (2002)
213.
[7] (a) M. Iyoda, T. Kondo, T. Okabe, H. Matsuyama, S. Sasaki, Y.
Kuwatani, Chem. Lett. (1997) 35;
This work was supported by a Grant-in-Aid for Scien-
tific Research on Priority Areas (No. 16033205, ‘‘Reaction
Control of Dynamic Complexes’’) and (No. 15550023)
from the Ministry of Education, Culture, Sports, Science
and Technology, Japan. We thank Ms. Shiduko Nakajo
(Division of Elemental Analysis, Iwate University) for ele-
mental analyses.
(b) M. Iyoda, T. Okabe, M. Katada, Y. Kuwatani, J. Organomet.
Chem. 569 (1998) 225;
(c) M. Iyoda, T. Takano, N. Otani, K. Ugawa, M. Yoshida, H.
Matsuyama, Y. Kuwatani, Chem. Lett. (2001) 1310.
[8] (a) N. Miyaura, A. Suzuki, Chem. Rev. 95 (1995) 2457;
(b) A.F. Littke, G.C. Fu, Angew. Chem., Int. Ed. 41 (2002) 4176;
(c) S. Kotha, K. Lahiri, D. Kashinath, Tetrahedron 58 (2002)
9633.
References
[9] (a) M. Araki, Bull. Chem. Soc. Jpn. 47 (1974) 1777;
(b) R.H.L. Kiebooms, P.J.A. Adriaensens, D.J.M. Vanderzande,
J.M.J.V. Gelan, J. Org. Chem. 62 (1997) 1473.
[10] G.M. Li, R.A. Zingaro, M. Segi, J.H. Reibenspies, T. Nakajima,
Organometallics 16 (1997) 756.
[11] P. Mathur, A.K. Singh, V.K. Singh, P. Singh, R. Rahul, S.M.
Mobin, C. Tho¨ne, Organometallics 24 (2005) 4793.
[12] Z. Hu, J.L. Atwood, M.P. Cava, J. Org. Chem. 59 (1994) 8071.
[13] C.D. Bryan, A.W. Cordes, R.C. Haddon, R.G. Hicks, R.T. Oakley,
T.T.M. Palstra, A.J. Perel, J. Chem. Soc., Chem. Commun. (1994)
1447.
[14] J.M. Manriquez, M.D. Ward, W.M. Reiff, J.C. Calabrese, N.L.
Jones, P.J. Carroll, E.E. Bunel, J.S. Miller, J. Am. Chem. Soc. 117
(1995) 6182.
[15] D.E. Richardson, H. Taube, Inorg. Chem. 20 (1981) 1278.
[16] (a) H. Bock, B. Roth, Phosphorus Sulfur 14 (1983) 211, and
references cited therein;
[1] (a) D. Fichou, Handbook of Oligo- and Polythiophenes, VCH,
Weinheim, 1999;
´
(b) P. Naguyen, P. Gomez-Elipe, I. Manners, Chem. Rev. 99 (1999)
1515;
(c) M. Iyoda, M. Hasegawa, Y. Miyake, Chem. Rev. 104 (2004)
5085.
[2] (a) S. Barlow, D. O’Hare, Chem. Rev. 97 (1997) 637;
(b) T.-Y. Dong, W.-Y. Lee, P.-T. Su, L.-S. Chang, K.-J. Lin,
Organometallics 17 (1998) 3323;
(c) H. Nishihara, Bull. Chem. Soc. Jpn. 74 (2001) 19;
(d) T. Ito, T. Hamaguchi, H. Nagino, T. Yamaguchi, H. Kido, I.S.
Zavarine, T. Richmond, J. Washington, C.P. Kubiak, J. Am. Chem.
Soc. 121 (1999) 4625;
(e) T. Hamaguchi, H. Nagano, K. Hoki, H. Kido, T. Yamaguchi,
B.K. Breedlove, T. Ito, Bull. Chem. Soc. Jpn. 78 (2005) 591.
[3] (a) D. Schro¨der, H. Schwarz, B. Lo¨brecht, W. Koch, S. Ogawa, Eur.
J. Inorg. Chem. (1998) 983;
(b) M. Shiotani, Y. Nagata, M. Tasaki, J. Sohama, J. Phys. Chem.
87 (1983) 1170;
(b) S. Ogawa, M. Kikuchi, Y. Kawai, S. Niizuma, R. Sato, J. Chem.
Soc., Chem. Commun. (1999) 1891;
(c) A.G. Davies, L. Julia, S.N. Yazdi, J. Chem. Soc., Chem.
Commun. (1987) 929;
(d) A.G. Davies, L. Julia, S.N. Yazdi, J. Chem. Soc., Perkin Trans. 2
(1989) 239;
(e) A.G. Davies, C.H. Schiesser, J. Organomet. Chem. 389 (1990)
301;
(f) A. Alberti, L. Favaretto, G. Seconi, J. Chem. Soc., Perkin Trans.
2 (1990) 931;
(g) I. Tabakovic, T. Maki, L.L. Miller, Y. Yu, Chem. Commun.
(1996) 1911;
(h) A. Wakamiya, T. Nishinaga, K. Komatsu, Chem. Commun.
(2002) 1192;
(c) S. Ogawa, T. Ohmiya, T. Kikuchi, A. Kawaguchi, S. Saito, A.
Sai, N. Ohyama, Y. Kawai, S. Niizuma, S. Nakajo, T. Kimura, R.
Sato, J. Organomet. Chem. 611 (2000) 136;
(d) N. Nagahora, S. Ogawa, S. Yoshimura, Y. Kawai, R. Sato, Bull.
Chem. Soc. Jpn. 76 (2003) 1043.
[4] (a) P.R. Buckland, N.P. Hacker, J.F.W. McOmie, J. Chem. Soc.,
Perkin Trans. 1 (1983) 1443;
(b) D.N. Nicolaides, K.E. Litinas, N.G. Argyropoulos, J. Chem.
Soc., Perkin Trans. 1 (1986) 415;
(c) G.M. Brooke, S.D. Mawson, J. Chem. Soc., Perkin Trans. 1
(1990) 1919;
(d) W. Volz, J. Voß, Synthesis (1990) 670;
(i) D. Yamazaki, T. Nishinaga, K. Komatsu, Org. Lett. 6 (2004)
4179.
(e) A. Ishii, J. Nakayama, J. Kazami, Y. Ida, T. Nakamura, M.
Hoshino, J. Org. Chem. 56 (1991) 78;
[17] (a) R. Gerdil, E.A.C. Lucken, J. Am. Chem. Soc. 87 (1965) 213;
(b) P. Cavalieri d’Oro, A. Mangini, G.F. Pedulli, P. Spagnolo, M.
Tiecco, Tetrahedoron Lett. 10 (1969) 4179;
(f) Y. Okuda, M.V. Lakshmikantham, M.P. Cava, J. Org. Chem. 56
(1991) 6024;
(g) J.P. Selegue, K.A. Swarat, J. Am. Chem. Soc. 115 (1993) 6448;
(h) J. Roncali, Chem. Rev. 97 (1997) 173;
(c) L. Lunazzi, G. Placucci, M. Tiecco, Tetrahedron Lett. 13 (1972)
3847.
(i) E. Muller, R. Thomas, M. Sauerbier, E. Langer, D. Streichfuss,
¨
[18] A. Altomare, G. Cascarano, C. Giacovazzo, A. Guagliardi, M.
Burla, G. Polidori, M. Camalli, J. Appl. Crystallogr. 27 (1994)
435.
[19] A. Altomare, M. Burla, M. Camalli, G. Cascarano, C. Giacovazzo,
A. Guagliardi, A. Moliterni, G. Polidori, R. Spagna, J. Appl.
Crystallogr. 32 (1999) 115.
[20] P.T. Beurskens, G. Admiraal, G. Beurskens, W.P. Bosman, R. de
Gelder, R. Israel, J.M.M. Smits, The DIRDIF-99 program system,
University of Nijmegen, Netherlands, 1994.
Tetrahedron Lett. 12 (1971) 521;
(j) L. Saris, M.P. Cava, J. Am. Chem. Soc. 98 (1976) 867;
(k) D.O. Cowan, A. Kini, L.Y. Chiang, K. Lerstrup, D.R. Talham,
T.O. Poehler, A.N. Bloch, Mol. Cryst. Liq. Cryst. 86 (1982) 1;
(l) D. Lorcy, M.P. Cava, Adv. Mater. 4 (1992) 562;
(m) P. Bauerle, G. Gotz, P. Emerle, H. Port, Adv. Mater. 4 (1992)
564;
(n) S. Musinanni, J.P. Ferraris, J. Chem. Soc., Chem. Commun.
(1993) 172;