Synthesis and electrochemical properties of 1,1′-bis (benzo-1,3-dithiol-2-ylidene)ferrocene derivatives as novel electron donor compounds

Article abstract of DOI:10.1016/S0022-328X(03)00694-6

A number of 1,1′-bis(benzo-1,3-dithiol-2-ylidene)ferrocene derivatives 7a-b and 12-14 based on the strong electron donating ability of 1,3-dithiole and ferrocene moieties were synthesized as new π-donors. The structure and physical properties of these compounds were characterized both by experimental techniques and spectral analysis. These new classes of donor compounds were obtained in very high yields based on modification of the Wittig-Horner reaction and the 1,3-dithiole rings were separated by conjugated spacers including aryl-ferrocenyl- aryl. The electrochemical properties of the new compounds have been studied in comparison to DB-TTF 4 analogues, and the parent ferrocene donor by cyclic voltammetry (CV), using Pt electrode as the working electrode in CH₂Cl₂ solutions at room temperature. Three subsequent oxidation processes are observed as three oxidation waves associated only with two reduction processes. Polycrystalline samples of 14a-b are conducting σ _rt 14a=0.2 S cm^-1 and σ _rt 14b=4.8×10^-4 S cm^-1) respectively, while compounds 15 and 16 were found essentially as insulator (σ _rt<10^-10 S cm^-1).

Full text of DOI:10.1016/S0022-328X(03)00694-6

Journal of Organometallic Chemistry 682 (2003) 49ꢀ58
/
www.elsevier.com/locate/jorganchem
Synthesis and electrochemical properties of 1,1?-bis(benzo-1,3-dithiol-
2-ylidene)ferrocene derivatives as novel electron donor compounds
Abd El-Wareth Sarhan *, Tatsuro Kijima, Taeko Izumi
Department of Chemistry and Chemical Engineering, Faculty of Engineering, Yamagata University, 3-16 Jonan 4-Chome, Yonezawa 992-8510, Japan
Received 27 April 2003; received in revised form 2 July 2003; accepted 14 July 2003
Dedicated to Prof. Dr. H.M.R. Hoffmann, Ph.D., D.Sc., to be professor emeritus at University of Hannover, Germany
Abstract
A number of 1,1?-bis(benzo-1,3-dithiol-2-ylidene)ferrocene derivatives 7aꢀ
/
b and 12ꢀ14 based on the strong electron donating
/
ability of 1,3-dithiole and ferrocene moieties were synthesized as new p-donors. The structure and physical properties of these
compounds were characterized both by experimental techniques and spectral analysis. These new classes of donor compounds were
obtained in very high yields based on modification of the Wittigꢀ
/
Horner reaction and the 1,3-dithiole rings were separated by
conjugated spacers including arylꢀferrocenylꢀaryl. The electrochemical properties of the new compounds have been studied in
/
/
comparison to DB-TTF 4 analogues, and the parent ferrocene donor by cyclic voltammetry (CV), using Pt electrode as the working
electrode in CH2Cl2 solutions at room temperature. Three subsequent oxidation processes are observed as three oxidation waves
associated only with two reduction processes. Polycrystalline samples of 14aꢀ
4.8ꢃ
10ꢂ4 S cmꢂ1) respectively, while compounds 15 and 16 were found essentially as insulator (srtB
# 2003 Elsevier B.V. All rights reserved.
/
b are conducting srt 14aꢁ
/
0.2 S cmꢂ1 and srt 14bꢁ
/
/
/
10ꢂ10 S cmꢂ1).
Keywords: Ferrocene-dialdehydes; Benzo-1,3-dithiole-2-ylidene moieties; Wittigꢀ/Horner reaction; Organic conductors; Electrochemical properties;
Cyclic voltammetry
1. Introduction
tetracyanoquinodimethane (TCNQ) between adjacent
stacks were extensively recognized [3]. Recently, Martin
and Segura have reported that, the utility of TTF as
building blocks in macromolecular and supramolecular
structures, as well as molecule based ferromagnetic
properties, as synthetic intermediates in organic chem-
Tetrathiafulvalene (TTF) and its analogues were
prepared as strong electron-donor compounds for the
development of electrically conducting materials. The
first organic metal TTF-TCNQ was discovered after
TTF was first synthesized by Wudl in 1970 [1]. While,
the first organic molecule based superconductor was
prepared from TTF analogue called tetramethyltetrase-
lenafulvalene (TMTSF) in 1979 [2a]. The topics of
organic metals have been reviewed by several authors
during the last three decades [2]. After the discovery of
istry, as a donor moiety in intramolecular donorꢀ
/
acceptor (DꢀA) systems in nonlinear optic (NLO)
/
materials and in association with the fullerene core, as
well as in the preparation of liquid crystalline materials
and LangmuirꢀBlodgett (LB) films has made TTF one
/
of the most extensively studied molecules [4].
metallic behavior of the TTFꢀTCNQ complex, various
synthetic approaches to TTFs and tetraselenafulvalenes
gained wide attention and charge-transfer from TTF to
/
Chemical modifications of the TTF framework have
been added to improve their electrical conductive
properties. Several TTFs like BEDT-TTF (1) and TTF
(2) were previously prepared via one step reaction with
different yields [5]. Bis-(ethylenedithio)tetrathiafulvalene
(BEDT-TTF) (1) has been widely used for the prepara-
tion of different organic superconductors [6] (Chart 1).
TTFs containing two or more fused or covalently
* Correspondence author. Permanent address: Chemistry
Department, Faculty of Science, Assiut University, Assiut 71516,
Egypt; fax: ꢄ20-88-312-564.
/
E-mail address: elwareth@acc.aun.edu.eg (A. El-Wareth Sarhan).
0022-328X/03/$ - see front matter # 2003 Elsevier B.V. All rights reserved.
doi:10.1016/S0022-328X(03)00694-6

50
A. El-Wareth Sarhan et al. / Journal of Organometallic Chemistry 682 (2003) 49ꢀ
/58
Chart 1.
attached TTFs units have been also used for preparing
super conducting salts [7].
Following the methods previously described in litera-
ture [13], the 1-(p-formylphenyl)-1?-(4-formyl-1-
naphthyl)ferrocene (10) and 1-(m-formylphenyl)-1?-(3-
formyl-2-methoxyphenyl)ferrocene (11) intermediates
were prepared. The synthesis of the dialdehydes 10
was carried out by Gomberg’s arylation of p-(ethox-
ycarbonyl)ferrocene with diazonium salt derived from 4-
ethoxycarbonyl-1-naphthylamine, followed by reduc-
tion with LiAlH4 and oxidation with activated MnO2
in dry CHCl3 (Scheme 2).
In the same manner the 1-(m-formylphenyl)-1?-(3-
formyl-5-methoxyphenyl)ferrocene (11) was synthesized
according to Gomberg’s arylation of ferrocene with
diazonium salt of the methyl 3-amino-2-methoxybenzo-
ate to afford the corresponding 3-methoxycarbonyl-2-
methoxyphenylferrocene which subjected to diazotiza-
tion with diazonium salt derived from methyl 3-amino-
benzoate, followed by reduction with LiAlH4 and
oxidation with activated MnO2 in dry CHCl3 (Scheme
3).
Since, Ueno et al. have prepared the first compound
belonging to ferrocene-tetrathiafulvalenes (Fc-TTF) as a
cis/trans isomeric mixture and was shown to form 1:1
CT complexes with both TCNQ and DDQ respectively
[8]. A few reports have appeared dealing with the
electrochemical properties and CT complexes of the
dithiafulvalenes and tetrathiafulvalenes having ferro-
cene moiety [9]. Martin and Segura have reported
recently that TTF is a molecule with unique electronic
properties that challenges the creativity and inventive-
ness of chemists in areas such as organic, polymer and
material chemistry and supramolecular chemistry [4].
These findings have prompted us to synthesize and
investigate the electrochemical properties of novel TTF
derivatives separated by insertion of a ferrocene moiety
as conjugated spacer between the two 1,3-dithiole rings
of the TTF (Chart 1).
Upon reaction of the dialdehyde 10 with the benzo-
1,3-dithiole-2-phosphonate (6) using slight modification
of the Wittigꢀ
was carried out at ꢂ
/
Horner procedures, by virtue the reaction
5 to ꢂ20 8C and afforded the
expected donor 12 as red crystals in 80.5% yield as
2. Results and discussions
/
/
In this work we report a synthesis of novel TTF
derivatives as new electron donors using the direct
shown in Scheme 4.
In the same manner, reaction of the dialdehydes 11
with 6 gave the expected unsymmetric 1-[3-(benzo-1,3-
dithiol-2-ylidene)methylphenyl]-1?-{5-methoxy-3-
[(benzo-1,3-dithiol-2-ylidene)methyl]phenyl}ferrocene
Wittigꢀ
dicarbonyl derivatives (5aꢀ
/
Horner cross coupling reaction. 1,1?-Ferrocene
/b) were synthesized cleanly
and in high yields according to the reported methods
[10]. The benzo-1,3-dithiole-2-phosphonate (6) was
obtained in a relatively high yield as mentioned in the
literature [11].
Reaction of ferrocene-1,1?-dicarboxaldehyde (5a) or
1,1?-diacetylferrocene (5b) with 6 in dry THF in the
(13) as orangeꢀ
During this work we found that the addition of the
ferrocene-dialdehydes to dithiolium salts at about ꢂ20
to ꢂ5 8C with continuous stirring efficiently uses the
WittigꢀHorner reaction, offering short reaction times
/red crystals in 97% yield (Scheme 5).
/
/
/
presence of n-BuLi at ꢂ
/
78 8C following to the Wittigꢀ
/
and high yields. The structure of both compounds 12
1
Horner reaction method afforded the corresponding
1,1?-bis[(benzo-1,3-dithiol-2-ylidene)methyl/ethyl]-ferro-
and 13 were determined using IR, H-NMR, 13C-NMR
1
and FABMS spectral and elemental analyses. The H-
cenes (7aꢀb) in good yields as shown in Scheme 1. The
/
NMR spectra of compound 12 revealed besides the
CS2) another
donor 7a was prepared following the procedures re-
ported by Togni et al. as red crystals in good yield [12].
aromatic protons (18H) and 2H, (2 CHÄ
/

A. El-Wareth Sarhan et al. / Journal of Organometallic Chemistry 682 (2003) 49ꢀ
/58
51
Scheme 1.
8H as four sets at d 4.65 (t, Jꢁ
/
1.5 Hz, 2H), 4.56 (t, Jꢁ
/
The CT complexes 14aꢀb, 15 and 16 were subjected in
/
1.5 Hz, 2H), 4.35 (t, Jꢁ1.5 Hz, 2H), 4.28 (t, Jꢁ
/
/
1.5 Hz,
the form of polycrystalline pressed pellets to measure-
ments of the electrical conductivity at room temperature
by the four-probe method. The results obtained are
summarized along with the physical properties in Table
1.
2H) belongs to ferrocene-H; see Section 4 for full details.
The DB-TTF 4 was prepared according to the method
described in the literature [11a,14]; for comparison study
of the electrochemical behavior using the CV with the
synthesized compounds 7aꢀ
/
b [12,15], 12 and 13.
The CT complex 14a was found in agreement with the
previously prepared by Togni et al. [12]. The electrical
conductivity measurements thus obtained are summar-
ized in Table 1, whereas CT complex 14a showed a
2.1. Synthesis of charge-transfer complexes
Compounds 7aꢀb, 12 and 13 were found to readily
substantial conductivity (sꢁ
exhibited less conductivity (sꢁ
and compounds 15 and 16 are essentially as insulator
(s B
10ꢂ10 S cmꢂ1).
/
0.2 S cmꢂ1), complex 14b
4.8ꢃ
10ꢂ4 S cmꢂ1),
/
/
/
form CT complexes with the well-known organic
acceptor TCNQ (Chart 2). While the CT complex of
the donor 12 was obtained under reflux temperature for
long time and long standing (3 months) at room
temperature in 21% yield (Chart 3). The donor com-
pounds and TCNQ were separately dissolved in equal
volumes of hot dichloromethane and the solution mixed
and briefly stirred.
The dark brown solution was allowed to slowly cool
to room temperature, whereby fine dark greenꢀ
crystals of the corresponding CT complexes 14aꢀ
and 16 were deposited. These were isolated in variant
yields. The CT complexes thus obtained were character-
ized using IR spectra and microanalysis and the results
are summarized in Table 3 and Section 4.6. Complexes
/
2.2. Electrochemistry
The electrochemical properties of the synthesized 1,1?-
di-substituted ferrocenes 7aꢀ
the ferrocene, and DB-TTF 4 and the ferrocene-
dialdehyde derivatives 5aꢀb, 10 and 11 were investigated
by cyclic voltammetry (CV) in CH2Cl2, 5ꢃ
10ꢂ3 con-
centration. The ferrocene-dialdehydes 5aꢀb, 10 and 11
/b, 12 and 13 compared to
/
black
/
/b, 15
/
/
showed one pair of redox waves corresponding to one-
electron transfer process. The redox potentials are
summarized in Table 2.
14aꢀ
/
b, 15 and 16 showed strong nCN bands at 2190,
The electrochemical properties of the new synthesized
2123 (14a) [12], 2154 (14b), 2221, 2186 (15) cmꢂ1
respectively, indicative of partially reduced TCNQ
([(TCNQ)2]ꢂ) [16]. The nCN band for complexes 15 is
shifted to 2154 cmꢂ1 compared to 2223 cmꢂ1 for
TCNQ, indicating that in this complex only weak
charge-transfer interactions are existed.
ferrocene-dialdehyde derivatives 5aꢀb, 10 and 11 were
/
investigated by CV (Fig. 1). The electrochemical results
of the investigated compounds were compared to that of
ferrocene and summarized in Table 2. These results
indicate that there is a significant difference between the
electrochemical behaviors of ferrocene aliphatic-alde-
Scheme 2.

52
A. El-Wareth Sarhan et al. / Journal of Organometallic Chemistry 682 (2003) 49ꢀ58
/
Scheme 3.
hyde derivatives like 5a and 5b and ferrocene aromatic-
aldehyde derivatives 10 and 11.
These results indicate also that the separation of the
anodic and the cathodic peak potentials, DEp values are
the same for compounds 5a and 5b, while, a small
positive shift in the formal potential, E0/, (58 mV) for
compound 5a was observed in compared to compound
5b. This shift can be attributed to the replacement of
hydrogen atom in 5a by the electron donating methyl
group in 5b, which facilitate the redox process of
compound 5b. On the other hand, the cyclic voltam-
metric behavior of compounds 10 and 11 are more or
less the same, in which DEp values are 93 and 91 mV for
10 and 11, respectively, whereas, a positive shift of 65
mV in the E0/ was observed for compounds 10 in
compared to compound 11. This confirm that the
introducing of methoxy group in compound 11 enhance
Scheme 4.
Scheme 5.

A. El-Wareth Sarhan et al. / Journal of Organometallic Chemistry 682 (2003) 49ꢀ
/58
53
Chart 2.
Table 2
Cyclic voltammetric data in millivolts of ferrocenyl ketones, recorded
on a Pt working electrode, Pt gauze counter electrode and Ag/AgCl
reference electrode in CH2Cl2 at ambient temperature, scan rate 200
mV using TBAP 0.1 mol lꢂ1 concentration as supporting electrolyte
Compound
Epc/mV
Epa/mV
E0\/mV
DEp/mV
Ferrocene
485
1041
983
564
1141
1083
725
525
1091
1033
679
79
100
100
93
5a
5b
10
11
Chart 3.
632
568
659
614
91
the electron transfer process and consequently its redox
behavior.
The electrochemical behaviors of ferrocene-dialde-
scan rate (ꢀ
800 mV sꢂ1) leads to a decrease and finally
almost a disappearance of the splitting in the reduction
direction and a well developed, one reduction process
was observed. The aforementioned results confirm that
/
hyde derivatives 5aꢀ
by the scan rate, in which at higher scan rate, n (n ]
mV sꢂ1), broadening of DEp was observed (DEpꢀ
/b, 10 and 11 are markedly affected
/
600
/
150
mV), indicating that the irreversibility of the electron-
transfer process was maintained under this condition,
possibly due to the onset of kinetic complications.
The electrochemical redox properties of compounds
the electrochemical behaviors of compounds 7aꢀb,
/
where ferrocene is a spacer of the two 1,3-dithiole units,
and 12 and 13, where conjugated spacers like phenyl or
naphthyl rings are connected in between both ferrocene
and 1,3-dithiole units, are different (Table 3). This
indicates that the interaction of ferrocene with the
7aꢀb, 12 and 13 were studied by CV and the data are
/
listed in Table 2. The CV behavior of these compounds
were shown in Fig. 2, and two couples of redox waves
were observed clearly in the cyclic voltammograms for
DTF rings directly as 7aꢀb or through conjugated
/
spacers as for 12 and 13 causes significant changes in
the electron donating properties and consequently the
electrochemical behaviors of these compounds. Com-
paring the data of compound 7a with that previously
prepared by Togni et al. we found that the CV data
obtained here was in agreement with that reported [12].
Controlled potential coulometry in corresponding to the
all compounds in the potential range ca 0.20ꢀ
/
1.2 V at
100 mV sꢂ1). The first couple of
lower scan rate (50ꢀ
/
redox waves in the potential range ca 200ꢀ800 mV is
/
due to the redox process of DTF/DTFꢄ system.
Whereas the second couple of redox waves in the
potential range ca 600ꢀ
Fc/Fcꢄ redox process. However, at higher scan rate
(200ꢀ
800 mV sꢂ1), an additional oxidation process was
/1000 mV is attributed to the
first anodic step (Eꢁ445 mV) consumed one electron/
/
/
molecule. We also found that the third anodic process in
all cases is irreversible in character. Analysis of the cyclic
voltammograms relevant to the first oxidation process
with scan rates varying from 100 to 1200 mV sꢂ1 shows
observed for the investigated compounds in the presence
of CH2Cl2 as solvent, which attributed to the second
DTFꢄ/DTF2ꢄ redox system. Further increasing of the
Table 1
Physical properties of the CT-complexes 14aꢀ
/
b, 15 and 16
Mol. formula (M.Wt)
50H26FeN8S4 (922.896)
No.
Color
Yield (%)
D/A ratio
srt (S cmꢂ1
)
14a
14b
15
Black
Black
Green
Black
47 mg (81)
84 mg (91)
62 mg (45)
30 mg (21)
C
1:2
1:2
1:2
1:2
0.2
C52H30FeN8S4 (950.949)
C63H36FeN8OS4 (1105.113)
C66H36FeN8S4 (1125.151)
4.8ꢃ
4.8ꢃ
4.8ꢃ
/
10ꢂ4
B
B/
/
/
10ꢂ10
10ꢂ10
16
/

54
A. El-Wareth Sarhan et al. / Journal of Organometallic Chemistry 682 (2003) 49ꢀ58
/
Fig. 1. Cyclic voltammograms of Fc-dialdehydes 5aꢀ/b, 10 and 11 in
CH2Cl2 as the same conditions described in Table 2.
Fig. 3. Cyclic voltammograms of compound 12 in CH2Cl2 at scan
rates from 50 to 1200 mV.
conjugated spacers changed the electron-donating abil-
ity of compounds 7aꢀb, 12 and 13 (Fig. 3).
/
A striking feature of the data for 12 and 13 is that the
third oxidation process from the second 1,3-dithiol-2-
ylidene to 1,3-dithiol-2-ylideneꢄ cation radical can be
clearly observed at scan rate ꢁ
becoming irreversible at higher scan rates (200ꢀ
/
100 mV (Fig. 4), while
1200
/
mV). We therefore assign this feature to the oxidation of
the entire delocalized system involving significant inter-
action between the two 1,3-dithiole rings and ferrocene
from one side, and aromatic rings and ferrocene from
the other side.
The minimum energy conformation of compound 12
is shown in Fig. 5. The donor molecule adopts a trans-
conformer with the central ring in a non-planer con-
formation, which is in agreement with the suggested
structures. The conjugation between the donor and the
ferrocene moiety is rather pronounced, corresponding to
the experimental data. Semi-empirical calculations AM1
of compound 12 using WinMopac showed that the
ferrocenyl and benzo-1,3-dithiol-2-ylidene moieties both
Fig. 2. Cyclic voltammograms of Fc-TTF 7aꢀb, 12 and 13, in CH2Cl2
at scan rate 200 mV.
/
Table 3
Cyclic voltammetric data of TTF 4 and p-donors 7aꢀ
/b, 12 and 13 in
CH2Cl2 at 200 mV
Compound
Epc/mV
P1 P2
Epa/mV
P1 P2
E0\/mV
P1 P2
DEp/mV
P1
P2
TTF 4
7a
7b
696 1061 751 1165 724 113
55 104
941 367 879 105 124
314
361
512
457
817 419
876 446
585 602
593 526
955 404 916
755 557 670
659 492 626
85
90 170
69 66
79
12 *
13 **
* Epa3
** Epa3
ꢁ
ꢁ
/
868.
/783.
that the peak-to-peak separation progressively increases
from 69 to 283 mV.
Increasing the scan rate (200ꢀ1200 mV) leads to
/
complete separation of the oxidation potential waves,
while the second and third associated reduction peaks
totally disappeared. Interaction of ferrocene with the
benzo-1,3-dithiol-2-ylidene moiety directly or through
Fig. 4. Cyclic voltammograms of Fc-10 and donor 12 recorded in
CH2Cl2 at scan rate 100 mV.

A. El-Wareth Sarhan et al. / Journal of Organometallic Chemistry 682 (2003) 49ꢀ
/58
55
4. Experimental
Melting points were recorded on a Gallencamp
melting point apparatus and are uncorrected. Infrared
spectra (IR) were measured on a Hitachi 260-10 spectro-
meter (Hitachi Ltd, 1-5-1, Marunouchi, Chiyod-ku,
1
Tokyo, Japan). H-NMR and 13C-NMR spectra were
recorded at room temperature on INOVA-Varian
Nuclear Magnetic Resonance Spectrometer (500
MHz). Chemical shifts are denoted in d units (ppm),
relative to Me4Si as internal standard, J values are given
in Hz. CDCl3 is used as a deuterated solvent unless
otherwise stated. MS and FABMS spectra were ob-
tained using a JEOL JMS-AX505HA. CV was measured
on a potentiostat (Model CS-1090/Model CS-1087).
Column chromatography was performed on silica gel
Fig. 5. AM1-optimized geometry of 12 for minimum energy con-
formation calculated by WinMopac (heat of formationꢁ324.40441
kcal molꢂ1).
/
have large atomic orbital coefficients in the HOMO level
indicative of a highly delocalized system involving
significant interaction between the ferrocene and 1,3-
dithiol ring systems [12].
60 (230ꢀ
/
400 Mesh ASTM). Solvents were distilled
b were prepared following
the previously reported methods [12,15].
before use. Compounds 7aꢀ
/
4.1. Synthesis of ferrocene-di-aromatic aldehydes 10 and
11
3. Conclusions
A mixture of ferrocene-dialcohol 8 (3 g, 6.7 mmole)
and MnO2 (30 g) was stirred at room temperature (r.t.)
in CHCl3 (300 ml) for 15 h. The reaction mixture was
filtered off through glass wool and the filtrate was
distilled under reduced pressure at 30 8C. The residue
was chromatographed on silica gel using chloroform/
hexane (3:1) to give the corresponding ferrocene-di-
aldehydes 10 and 11.
In conclusion, we have described a short and efficient
synthetic route for the useful 1,1?-ferrocene-dialdehydes
5aꢀ
/
b, 10 and 11. The potentially useful symmetric 1,1?-
bis(benzo-1,3-dithiol-2-ylidene)ferrocenes 7aꢀ
/b
and
asymmetric 12 and 13 were synthesized successfully
and the electrochemical properties in comparison with
ferrocene and DB-TTF 4 were investigated. The p-
donor ability of the synthesized compounds makes them
good candidates for the preparation of organic metals.
In our present work we have found that the addition of
4.2. 1-(p-Formylphenyl)-1?-(4-formyl-1-
naphthyl)ferrocene (10)
the aldehydes to the dithiolium salts at about ꢂ
5 8C with continuous stirring is an efficient use for the
WittigꢀHorner reaction. The electrochemical study
reveals that these compounds 7aꢀb and 12ꢀ13 exhibit
/
20 to ꢂ
/
/
Dark red crystals, m.p. 106ꢀ107 8C, yield 2.2 g, 73%,
/
/
/
IR (KBr) n 3089m, 2973m, 1691s, 1602s, 1567s, 1513s,
1
1216s, 1168s, 1058s, 829s, 765s cmꢂ1. H-NMR (500
MHz, CDCl3) d 10.35 (s, 1H, CHO), 9.92 (s, 1H, CHO),
good donor properties, shown in the three subsequent
oxidation processes. The results confirm that the
electrochemical behaviors of compounds 7aꢀb, where
/
9.30 [dd, Jꢁ
thalene-H)], 8.54 [dd, Jꢁ
CH (naphthalene-H)], 7.82 (d, Jꢁ
lene-H), 7.66 (m, 3H, aromatic-H), 7.63 (m, 1H,
aromatic-H), 7.45 (d, Jꢁ8 Hz, 2H, aromatic-H), 4.72
(t, Jꢁ1.5 Hz, 2H, ferrocene-H), 4.64 (t, Jꢁ1.5 Hz, 2H,
ferrocene-H), 4.45 (t, Jꢁ1.5 Hz, 2H, ferrocene-H), 4.37
(t, Jꢁ
1.5 Hz, 2H, ferrocene-H). 13C-NMR (125 MHz,
/
8.5 Hz, Jꢁ
/
0.5 Hz, 1H, CHÄ
8.5 Hz, Jꢁ0.5 Hz, 1H, CHÄ
1 Hz, 2H, naphtha-
/
CH (naph-
ferrocene is a spacer of the two 1,3-dithiole units, and 12
and 13, where conjugated spacers like phenyl or
naphthyl rings are connected in between both ferrocene
and 1,3-dithiole units, are different. Polycrystalline
/
/
/
/
/
samples of 14aꢀ
and srt 14bꢁ4.8ꢃ
compound 15 and 16 are essentially as insulators (srtB
/
b are conducting srt 14aꢁ
/
0.2 S cmꢂ1
/
/
/
/
10ꢂ4 S cmꢂ1 respectively, while
/
/
/
10ꢂ10 S cmꢂ1). The molecular structure of compounds
12 and 13 was optimized geometrically using WinMopac
calculation program and the AM1-optimized geome-
tries. The combination of different donor fragments
within the same molecule affords systems from which
one or two electrons can be reversibly removed.
CDCl3) d 192.92, 191.57 (2 CHO), 145.56, 143.53
(aromatic-C), 135.55, 134.23 (aromatic-C), 131.85,
131.13 (aromatic-C), 129.81, 129.57, 128.64, 126.85,
126.44, 126.36, 126.32, 125.14 (aromatic-CH), 86.47,
84.30 (ferrocene-C), 72.49, 72.27, 71.40, 68.85 (ferro-
cene-CH). FABMS m/z [Mꢄ, 444 (92)].

56
A. El-Wareth Sarhan et al. / Journal of Organometallic Chemistry 682 (2003) 49ꢀ58
/
4.3. 1-(3-Formylphenyl)-1?-(3-formyl-5-
methoxyphenyl)ferrocene (11)
(CH Ä
/
C), 112.52 (CH Ä
/
C), 87.65, 86.02 (ferrocene-C),
71.77, 70.96, 70.39, 67.89 (ferrocene-CH). FABMS m/z
(%) [Mꢄ, 716 (18)]. Anal. Calc. for C42H28FeS4: C,
70.38; H, 3.94; S, 17.89. Found: C, 70.04; H, 4.20; S,
18.08%.
Orange red crystals, m.p. 87ꢀ88 8C, yield 71%, IR
/
(KBr) n 3095s, 2975w, 2840m, 2800s, 2721s, 1702s,
1677s, 1590s, 1504s, 1461s, 1438s, 1388s, 1272s, 1249s,
1186s, 1147s, 1079s, 1018s, 935s, 815s, 790s, 688s cmꢂ1
.
4.5. 1-[3-(Benzo-1,3-dithiol-2-ylidenemethyl)phenyl)]-
1?-[3-(benzo-1,3-dithiol-2-ylidene-methyl)-2-
methoxyphenyl]-ferrocene (13)
1H-NMR (500 MHz, CDCl3) d 9.8 (s, 1H, CHO), 9.7 (s,
1H, CHO), 7.62ꢀ7.18 (m, 6H, aromatic-CH), 6.67 (m,
/
1H, aromatic-CH), 4.82 (s, 2H, ferrocene-CH), 4.61 (s,
2H, ferrocene-H), 4.36 (s, 2H, ferrocene-H), 4.32 (s, 2H,
ferrocene-H), 3.81 (s, 3H, OCH3). 13C-NMR (125 MHz,
CDCl3) d 193.24, 191.76 (2 CHO), 162.10 (aromatic-C),
139.18, 137.19, 132.63, 130.56 (aromatic-C), 130.45,
129.55, 128.15, 127.09, 126.81, 111.72 (aromatic-CH),
86.00, 83.79 (ferrocene-C), 71.57, 71.24, 70.89, 68.68
(ferrocene-CH), 56.43 (OCH3). FABMS m/z (%) [Mꢄ,
424 (45)]. Anal. Calc. for C25H20FeO3: C, 70.77; H,
4.75. Found: C, 71.01; H, 4.51%.
Compound 13 was obtained as orange crystals in 97%
yield, m.p. 93ꢀ94 8C. IR (KBr) n 3083m, 3052m, 2992m,
/
2950m, 2830m, 2360m, 1598s, 1581s, 1558s, 1504s,
1448s, 1386m, 1268s, 1241s, 1153s, 1122s, 1081s,
1029s, 813s, 740s, 692s cmꢂ1
.
1H-NMR (500 MHz,
6.69
6.39 (dd,
2Hz, Jꢁ
2.5 Hz, Jꢁ1.5
2 Hz, Jꢁ1.5 Hz,
2H, ferrocene-H), 4.27 (dd, 2.5 Hz, Jꢁ1.5 Hz, 2H,
ferrocene-H), 3.77 (d, Jꢁ
2 Hz, 3H, OCH3). 13C-NMR
CDCl3) d 7.29ꢀ
(dd, Jꢁ2 Hz, Jꢁ
Jꢁ2 Hz, Jꢁ7 Hz, 1H, CHÄ
1.5 Hz, 2H, ferrocene-H), 4.53 (dd, Jꢁ
Hz, 2H, ferrocene-H), 4.30 (dd, Jꢁ
/
7.05 (m, 15H, aromatic-H), 6.71ꢀ
8.5 Hz, 1H, CHÄC), 6.41ꢀ
C), 4.73 (dd, Jꢁ
/
/
/
/
/
/
/
/
/
/
/
/
/
/
4.4. 1-[4-(Benzo-1,3-dithiol-2-ylidenemethyl)phenyl)]-
1?-[4-(benzo-1,3-dithiol-2-ylidene-methyl)naphthyl]-
ferrocene (12)
/
/
(125 MHz, CDCl3) d 154.83 (aromatic-C), 137.90,
136.55, 136.19, 135.00, 134.83, 131.65, 129.10, 129.03
(aromatic-C), 128.15, 127.73, 125.82, 125.74, 125.70,
125.50, 125.42, 125.35, 124.90, 124.27, 123.77, 121.65,
A sample of 1,3-benzodithiole 6 (0.56 g, 2.1 mmole) is
stirred in dry THF (50 ml) under a stream of N2 at ꢂ
/
78 8C. A solution of n-BuLi (1.5 ml, 2.6 mol lꢂ1 in
hexane) was added portion wise and the mixture was
stirred for 15 min. The reaction mixture was allowed to
120.83, 120.79 (aromatic-CH), 114.87 (CH Ä
/
C), 110.96
(CH ÄC), 86.22, 83.57 (ferrocene-C), 70.31, 70.29, 69.97,
/
69.73, 67.99 (ferrocene-CH), 55.22 (OCH3). FABMS m/
z (%) [Mꢄ, 696 (23)]. Anal. Calc. for C39H28FeOS4: C,
67.23; H, 4.05; S, 18.40. Found: C, 67.19; H, 4.26; S,
18.77%.
warm to ꢂ20 8C with continuous stirring and a solution
/
of dialdehyde 10 (0.444 g, 1.0 mmol) in dry THF (50 ml)
was added portionwise. The temperature of the reaction
was raised to r.t. and the reaction mixture was stirred for
a further 4 h. The THF was removed under vacuum and
the residue was washed with H2O and extracted with
CHCl3 and dried over Na2SO4. The crude oily product
was chromatographed on silica gel using CHCl3/hexane
(1:2) to give in the early fractions 0.58 g orange crystals
4.6. Preparation of charge-transfer complexes 14a, 14b,
15 and 16
4.6.1. Charge-transfer complexes 14aꢀb
/
of 12 (80.5%) m.p. 111ꢀ113 8C. IR (KBr) n 3087w,
/
Donor 7a or 7b (67 mg, 0.125 mmol) and TCNQ (51
mg, 0.25 mmol) were dissolved in equal amounts of 1,2-
dichloromethane (15 ml), the solutions were heated to
reflux temperature. The solution of 7a or 7b was then
added to that of TCNQ and the resulting dark green
solution briefly stirred. Slow cooling to r.t. led to the
formation of dark crystals. These were filtered off,
washed with small portion of 1,2-dichloromethane,
and dried under vacuum to give the corresponding
CT-complexes 14a and 14b respectively in high yields.
3054m, 2952w, 2917w, 2848w, 2358m, 1654s, 1577s,
1548s, 1446s, 1386m, 1285m, 1159m, 1122s, 1083s,
1029s, 842s, 761s, 738s, 678s cmꢂ1 1H-NMR (500
.
MHz, CDCl3) d 8.5 [(d, Jꢁ
(naphthalene-H)], 8.02 [d, Jꢁ8.5 Hz, 1H, CHÄ
(naphthalene-H)], 7.73 (d, Jꢁ
H), 7.53 (d, Jꢁ7 Hz, 1H, naphthalene-H), 7.45 (m, 2H,
naphthalene-H), 7.36 (d, Jꢁ8.5 Hz, 2H, aromatic-H),
7.25ꢀ7.05 (m, 11H, aromatic-H and CHÄC), 6.5 (s, 1H,
CHÄC), 4.65 (t, Jꢁ1.5 Hz, 2H, ferrocene-H), 4.56 (t,
Jꢁ1.5 Hz, 2H, ferrocene-H), 4.35 (t, Jꢁ1.5 Hz, 2H,
ferrocene-H), 4.28 (t, Jꢁ
1.5 Hz, 2H, ferrocene-H). 13C-
/
8 Hz, 1H, CHÄ
/
CH
/
/CH
/7.5 Hz, 1H, naphthalene-
/
/
/
/
/
/
/
/
/
4.6.2. CT-complex 14a
NMR (125 MHz, CDCl3) d 136.56, 135.98, 135.94,
135.14, 134.78, 134.68, 134.28, 132.77, 131.93, 131.36,
Yield 47 mg, 81%. Data were in agreement with that
reported in literature [12]. Anal. Calc. for
C50H26FeN8S4 (922.896): C, 65.07; H, 2.84; N, 12.14;
S, 13.89. Found: C, 65.28; H, 3.10; N, 12.04; S, 13.92.
Found: C, 65.28; H, 3.10; N, 12.04; S, 13.92.
131.08 (aromatic-C, 2 CHÄ
/
C), 127.49, 126.87, 126.52,
126.29, 125.90, 125.75, 125.62, 125.51, 124.38, 123.89,
121.70, 121.67, 121.04, 120.89 (aromatic-CH), 114.66

A. El-Wareth Sarhan et al. / Journal of Organometallic Chemistry 682 (2003) 49ꢀ
/58
57
Chem. Soc. 95 (1973) 948;
4.6.3. CT-complex 14b
(c) L.B. Coleman, M.J. Cohen, D.J. Sandman, F.G. Yamagishi,
A.F. Garito, A.J. Heeger, Solid State Commun. 12 (1973) 1125;
(d) F. Wudl, J. Am. Chem. Soc. 97 (1975) 1962;
(e) F. Wudl, C.H. Ito, A. Nagel, J. Chem. Soc. Chem. Commun.
(1973) 923.
Yield 84 mg, 91%. IR (KBr) n 2202s, 2154s, 1598m,
1558s, 1508s, 1430s, 1388s, 1288s, 1191s, 1120s, 1066s,
1024s, 950s, 835s, 736s, 688s cmꢂ1. Anal. Calc. for
C52H30FeN8S4 (950.9488): C, 65.68; H, 3.18; N, 11.78;
S, 13.48. Found: C, 65.48; H, 3.21; N, 11.93; S, 13.49%.
[4] J.L. Segura, N. Martin, Angew. Chem. Int. Ed. 49 (2001) 1372.
[5] (a) G. Coustumer, Y. Moller, J. Chem. Soc. Chem. Commun.
(1980) 38;
4.6.4. CT-complex 15
(b) Z. Yoshida, T. Kawase, H. Awaji, I. Sugimoto, T. Sugimoto,
S. Yoneda, Tetrahedron Lett. 24 (1983) 3469;
DTF-Fc-DTF 13 (87 mg, 0.125 mmol) and TCNQ (51
mg, 0.25 mmol) were dissolved in equal amounts of 1,2-
dichloroethane (15 ml), the solutions were heated to
reflux temperature. The solution of Fc-TTF 13 was then
added to that of TCNQ and the resulting brown red
mixture briefly stirred. Slow cooling to room tempera-
ture led to the formation of green crystals. These were
filtered off, washed with small portion of 1,2-dichlor-
oethane, and dried under vacuum to give 15 as dark
green crystals, yield 62 mg, 45%. IR (KBr) n 3050s,
2921m, 2890m, 2850m, 2362m, 2225s, 1654m, 1602m,
1573s, 1544s, 1511s, 1448s, 1282m, 1261m, 1159m,
1122s, 1014m, 862s, 840s, 761s, 740s cmꢂ1. Anal.
Calc. for C63H36FeN8OS4 (1105.113): C, 68.47; H,
3.28; N, 10.14; S, 11.77. Found: C, 68.14; H, 3.15; N,
9.86; S, 11.97%.
(c) A. Khanous, A. Gorgues, M. Jubault, Synth. Metals 41ꢀ
/
43
(1991) 2327;
(d) F. Bertho-Thoraval, A. Robert, P. Patail, P. Robin, Tetra-
hedron 46 (1990) 433;
(e) N. Okada, H. Yamochi, F. Shinozaki, K. Oshima, G. Saito,
Chem. Lett. (1986) 1861;
(f) E.S. Kozlov, A.A. Yurchenko, A.A. Tolmachev, L.A. Nechi-
tailo, N.V. Ignatev, Zh. Org. Chem. 26 (1990) 377;
(g) R.R. Schumaker, S. Rajeswari, M.V. Joshi, M.P. Cava, M.A.
Takassi, R.M. Metzger, J. Am. Chem. Soc. 111 (1989) 308;
(h) V.Yu. Khodorkovskii, A. Edzina, O. Neilands, J. Mol.
Electronics 5 (1989) 33;
(i) H. Inkuchi, G. Saito, P. Wu, K. Seki, T.B. Tang, T. Mori, K.
Imaeda, T. Inoki, Y. Higuchi, K. Inaka, N. Yasuoka, Chem. Lett.
(1986) 1263;
(j) M.R. Bryce, G. Cooke, A.S. Dhindsa, D. Lorcy, A.J. Moore,
M.C. Petty, M.B. Hursthouse, A.I. Karaulov, J. Chem. Soc.
Chem. Commun. (1990) 816;
(k) K. Bechgaard, C.S. Jacobsen, K. Mortensen, M.J. Pedersen,
N. Thoup, Solid State Commun. 33 (1980) 1119;
(l) S.S. Perkin, E. Engler, R.R. Schumaker, R. Lagier, V.Y. Lee,
J.C. Scott, R.L. Greene, Phys. Rev. Lett. 50 (1983) 270.
[6] (a) E.B. Yagubskii, Mol. Cryst. Liq. Cryst. 230 (1993) 139;
(b) G. Saito, Phosphorus Sulfur Silicon 67 (1992) 345;
(c) J.M. William, A.J. Shultz, U. Geiser, K.D. Carlson, A.M.
Kini, H.H. Wang, W.K. Kwow, M.H. Whango, J.E. Schirber,
Science 252 (1991) 1501.
4.6.5. CT-complex 16
This was obtained from DTF-Fc-DTF 12 (90 mg,
0.125 mmol) and TCNQ (51 mg, 0.25 mmol). The same
method described above followed by refluxing the
mixture in dry CH3CN for about 72 h. The resulting
brown solution was cooled and kept at r.t. for ꢁ
months. The precipitate thus formed was collected by
filtration and washed with chloroform (3ꢃ) and twice
with acetone to give 30 mg (21%) of dark brown crystals
of the CT-complex 16. IR (KBr) n 3050s, 2225s, 1602m,
1575s, 1546s, 1513s, 1448s, 1284m, 1187m, 1159m,
1122s, 1029s, 929m, 889m, 862s, 840s, 761s,
740s678s640s cmꢂ1. C66H36FeN8S4 (1125.151), FAB-
/
3
[7] (a) Y. Misaki, N. Higuchi, H. Fujiwara, T. Yamabe, T. Mori, H.
Mori, S. Tanaka, Angew. Chem. Int. Ed. Engl. 34 (1995) 1222;
(b) Y. Misaki, T. Ohta, N. Higuchi, H. Fujiwara, T. Yamabe, T.
Mori, H. Mori, S. Tanaka, J. Mater. Chem. 5 (1995) 570.
[8] Y. Ueno, H. Sano, M. Okawara, J. Chem. Soc. Chem. Commun.
(1980) 28.
/
[9] (a) A. Togni, Ferrocene-containing charge transfer complexes.
Conducting and magnetic materials, in: A. Togni, T. Hayashi
(Eds.), Ferrocenes, VCH, Weinheim, Germany, 1995, p. 434;
(b) A.J. Moore, M.R. Bryce, P.J. Skabara, A.S. Batsanov, L.M.
Goldenberg, J.A.K. Howard, J. Chem. Soc. Perkin Trans. 1
(1997) 3443;
MS m/z (%) [Mꢄ, 1125 (0.2), 919 (1)].
/
References
(c) S. Liu, I. Perez, N. Martin, L. Echegoyen, J. Org. Chem. 65
(2000) 9092;
(d) A. Sarhan, M. Murakami, T. Izumi, Monatsh. Chem. 133
(2002) 1055.
[1] (a) F. Wudl, G.M. Smith, E.G. Hufnagel, J. Chem. Soc. Chem.
Commun. (1970) 1453;
[10] (a) G.G.A. Balavoine, G. Dosneau, T. Fillebeen-Khan, J.
Organomet. Chem. 412 (1991) 381;
(b) J. Ferraris, D.O. Cowan, V.V. Walatka, J.H. Perlstein, J. Am.
Chem. Soc. 95 (1973) 948;
(b) K.L. Rinehart, Jr., K.L. Motz, S. Moon, J. Am. Chem. Soc. 79
(1957) 2749;
(c) L.B. Coleman, M.J. Cohen, J.D. Sandman, F.G. Yamagushi,
A.F. Garito, A.J. Heeger, Solid State Commun. 12 (1973) 1125.
[2] (a) A. Andrieux, C. Duroure, D. Jerome, K. Bechgaard, J. Phys.
Lett. 40 (1979) 381;
(c) G.W. Gokel, I.K. Ugi, J. Chem. Educ. 49 (1972) 294;
(d) R.B. Woodward, M. Rosenblum, M.C. Whiting, J. Am.
Chem. Soc. 74 (1952) 3458.
(b) A.N. Bloch, D.O. Cowan, T.O. Poehler, in: K. Masnda, M.
Silver (Eds.), Energy and Charge Transfer in Organic Semicon-
ductors, Plenum Publisher, New York, 1974;
[11] (a) J. Nakayama, Synthesis (1975) 38;
(b) A. Sarhan, T. Izumi, J. Chem. Res. (S) (2002) 11;
(c) J. Nakayama, K. Fujiwara, M. Hoshino, Chem. Lett. (1975)
1099;
(c) A.F. Garito, A.J. Heeger, Acc. Chem. Res. 7 (1974) 232.
[3] (a) M. Narita, C.U. Pittman, Jr., Synthesis (1976) 489 (and
references cited therein);
(d) K. Akiba, K. Ishikawa, N. Inamoto, Bull. Chem. Soc. Jpn. 51
(9) (1978) 2674.
(b) J. Ferraris, D.O. Cowan, V.V. Walatka, J.H. Perlstein, J. Am.

58
A. El-Wareth Sarhan et al. / Journal of Organometallic Chemistry 682 (2003) 49ꢀ58
/
[12] A. Togni, M. Hobi, G. Rihs, G. Rist, A. Albinati, P. Zanello, D.
Zech, H. Killer, Organometallics 13 (1994) 1224.
[13] (a) A. Kasahara, T. Izumi, I. Shimizu, T. Oikawa, H. Umezawa,
M. Murakami, O. Watanabe, Bull. Chem. Soc. Jpn 58 (1985)
1560;
N. Thorup, J. Becher, J. Org. Chem. 65 (2000) 5794;
(c) K. Lerstrup, D. Talham, A. Bloch, D. Cowan, J. Chem. Soc.
Chem. Commun. (1982) 336.
[15] (a) A. Sarhan, Y. Nauchi, T. Izumi, Tetrahedron 59 (2003)
6354;
(b) A. Kasahara, T. Izumi, H. Umezawa, Chem. Lett. (1980)
1039.
(b) A. Sarhan, T. Izumi, Organomet. Chem. 675 (2003) 1.
[16] (a) J.S. Miller, J.H. Zahng, J.H. Zhang, W.M. Reiff, D.A. Dixon,
L.D. Preston, A.H. Reis, Jr., E. Gebert, M. Extine, J. Troup, A.J.
Epstein, M.D. Ward, J. Phys. Chem. 91 (1987) 4344;
(b) M.D. Ward, D.C. Johnson, Inorg. Chem. 26 (1987) 4213.
[14] (a) G.S. Bajwa, K.D. Berlin, H.A. Bohl, J. Org. Chem. 41 (1976)
145;
(b) J.O. Jeppesen, K. Takimiya, F. Jensen, T. Brimert, K. Nielsen,