Functionalised polyferrocene complexes: Synthesis and mixed-valency properties

Article abstract of DOI:10.1039/b300397n

We have synthesised three types of hexamers bearing 6 or 12 electro-active groups by a cyclotrimerisation reaction of symmetric alkynes. Two types of electro-active groups were added to the ferrocene, being introduced either before (case of Rubipy) or after (case of BDT) cyclotrimerisation. While the characterisation of compounds with the BDT functionalisation can be carried out by NMR due to the complete symmetry of these molecules, complexes bearing the Rubipy fragment are obtained as mixtures of diastereoisomers and were characterised using electrospray or FAB mass spectrometric techniques. Alkynes and hexamers functionalised by the BDT group (1 and 2) gave interesting spectrochemical properties. Indeed, in the case of molecules bearing a double bond between the ferrocene and the phenyl core (1b and 2b), two mono-electronic oxidation waves are observed in the CVs, corresponding to the successive oxidation of two ferrocenes. In the case of 2b an intervalence band is observed in NIR region.

Full text of DOI:10.1039/b300397n

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P A P E R
Functionalised polyferrocene complexes: synthesis and
mixed-valency properties
Victor Mamane, Aurore Gref and Olivier Riant*y
´
Laboratoire de Catalyse Moleculaire, ICMO, Universite Paris-Sud, 91405, Orsay cedex, France
Received (in Montpellier, France) 9th January 2003, Accepted 5th January 2004
First published as an Advance Article on the web 26th March 2004
We have synthesised three types of hexamers bearing 6 or 12 electro-active groups by a cyclotrimerisation
reaction of symmetric alkynes. Two types of electro-active groups were added to the ferrocene, being introduced
either before (case of Rubipy) or after (case of BDT) cyclotrimerisation. While the characterisation of
compounds with the BDT functionalisation can be carried out by NMR due to the complete symmetry of these
molecules, complexes bearing the Rubipy fragment are obtained as mixtures of diastereoisomers and were
characterised using electrospray or FAB mass spectrometric techniques. Alkynes and hexamers functionalised
by the BDT group (1 and 2) gave interesting spectrochemical properties. Indeed, in the case of molecules
bearing a double bond between the ferrocene and the phenyl core (1b and 2b), two mono-electronic oxidation
waves are observed in the CVs, corresponding to the successive oxidation of two ferrocenes. In the case of 2b an
intervalence band is observed in NIR region.
benzodithiolene (BDT) group. A full account concerning the
Introduction
synthesis of these compounds as well as a more detailed elec-
trochemical and spectroscopic study is provided here. We also
wish to describe the synthesis and electrochemical behaviour of
the new polyferrocene complexes 3 and 4 (Scheme 1) in which
each ferrocene is attached to a ruthenium bipyridine (Rubipy)
moiety.
Electron transfer (ET) reactions1 are one of the most funda-
mental processes in chemistry2 and biology.3 Thus, numerous
investigations have been devoted to the study of ET processes
in real biological systems,4 in biomimetic model compounds,5
and in structurally simple and completely artificial low molecu-
lar weight systems.6 The preparation of the first mixed-valence
(MV) complex by Creutz and Taube in 19697 opened a new
area for the study of ET. In MV complexes, ET may be studied
under controlled intramolecular conditions: across a fixed dis-
tance, between two fragments with known properties and
through a ligand whose conformation and electronic charac-
teristics are well-defined. The aims range from the desire to
understand ET processes in nature to the design of molecular
wires for electronic communication.8
Owing to its high stability, ease of functionalisation, and
well-defined electrochemistry, ferrocene has been widely used
as redox-active centres that are linked together with a wide
variety of structural units such as saturated and unsaturated
carbon bridges,9 delocalised fused rings,9 and polymeric and
dendritic backbones.10,11 To the best of our knowledge, multi-
ferrocenyl systems in which each ferrocene is attached to
another electro-active group (organic or inorganic) are not
known. Here we present the synthesis and electrochemical
study of hexaferrocenyl molecules having each ferrocene
linked to an organic group (benzodithiolene) or an inorganic
group (Ru bipyridines) for the generation of MV complexes.
Two types of complexes have thus been synthesised, which
differ by the presence or not of a double bond between the fer-
rocene and the phenyl core (Scheme 1). This structural differ-
ence led us to consider two different pathways to introduce
the chiral ferrocene moiety. As depicted in Scheme 2, the
monomer 7a is obtained with 72% yield using a palladium-cat-
alysed cross-coupling reaction between a chiral orthometallated
ferrocenyl zinc intermediate and bis(p-bromophenyl)-
acetylene, followed by deprotection of the acetal groups.13
The vinyl analogue monomer 7b14 was obtained in 64% yield
by Siegrist condensation of two equivalents of the imine 614
with bis(p-tolyl)acetylene and subsequent deprotection of the
acetal groups. The [2 þ 2 þ 2] cyclotrimerisations of alkynes
7a and 7b were carried out in refluxing dioxane in the pre-
sence of a catalytic amount (10 mol %) of dicobalt octacar-
bonyl. Clean conversion was observed in both cases and the
corresponding enantiopure cyclotrimers 8a and 8b were iso-
lated as stable orange crystalline solids in 85% yield (Scheme 3).
The introduction of BDT groups on each ferrocene in
monomers 7a, 7b and cyclotrimers 8a, 8b was carried out using
a standard Wittig–Horner condensation. The two- and six-fold
condensation of phosphonate 915 on the bisaldehydes 7a, 7b
and hexaaldehydes 8a, 8b were conducted using t-BuOK as a
base in THF and gave the new enantiopure derivatives 1a,
1b and 2a, 2b, bearing, respectively, 4 and 12 electro-active
units, in moderate to good yields (Scheme 3).
Results and discussion
Synthesis
In a previous communication we described the synthesis and
preliminary electrochemical behaviour of four enantiopure
polyferrocene complexes 1–212 (Scheme 1). In these complexes
each ferrocene is linked to an organic electro-active
Ruthenium containing cyclotrimers 4a, 4b were synthesised
in three steps from monomers 7a, 7b. Bisaldehydes 7a, 7b were
condensed with phosphine oxide 1016 in good yields to give
compounds 11a, 11b bearing bipyridine group on each ferro-
cene. Complexation of the ruthenium moiety is performed by
refluxing compounds 11a, 11b in ethanol. Complexes 12a–
12d were obtained in moderate yields after precipitation
with ammonium hexafluorophosphate and purification by
´
y New address: Laboratoire de Chimie Organique et Medicinale,
´
´
Departement de Chimie, Universite Catholique de Louvain, Place
Louis Pasteur 1, 1348 Louvain la Neuve, Belgium. Fax
þ32(0)10474168, E-mail: riant@chim.ucl.ac.be
T h i s j o u r n a l i s Q T h e R o y a l S o c i e t y o f C h e m i s t r y a n d t h e
C e n t r e N a t i o n a l d e l a R e c h e r c h e S c i e n t i f i q u e 2 0 0 4
N e w . J . C h e m . , 2 0 0 4 , 2 8 , 5 8 5 – 5 9 4
585

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Scheme 1
chromatography on silica gel (Scheme 4). The 1H NMR
analysis displayed a complex spectra, which was attributed
to the presence of a diastereoisomeric mixture due to the
introduction of two new chiral ruthenium centres. During
our early experiments, we tried to cyclotrimerise complexes
12c, 12d bearing unsubstituted bipyridine ligands. However,
the corresponding complexes are completely insoluble in
dioxane, even at refluxing conditions. No conversion was
also obtained by using acetonitrile as a cosolvent of dioxane
as the presence of acetonitrile seems to accelerate the decom-
position of the catalyst. Introduction of several tert-butyl
groups on bipyridines increases the solubility of these com-
plexes in non-coordinating solvents such as chlorinated
solvents.
Finally, [2 þ 2 þ 2] cyclotrimerisations of complexes 12a, 12b
were successfully performed by reacting the monomers with a
catalytic amount (10 mol %) of dicobalt octacarbonyl in a
refluxing mixture of 1,2-dichloroethane–dioxane (Scheme 5).
After purification by chromatography on silica gel, cyclo-
trimers 4a and 4b were isolated in 70% and 53% yields,
respectively. The presence of a mixture of diastereomers is
1
revealed in the H NMR spectra by broad peaks.
Mass spectrometry of ruthenium complexes
As mentioned above, characterisation of complexes 12 and 13
by NMR spectroscopy was made difficult due to the presence
of a diastereoisomeric mixture. Obtaining an unequivocal
structure analysis of these complexes required a mass spectro-
scopic analysis. Complexes 12 were easily analysed by electro-
spray ionisation (ESI) mass spectroscopy, which showed
molecular ions M4þ and M3þ. In the case of complex 12c we
also observed the molecular ions M2þ and Mþ.
Electrospray MS spectra of complexes 12a and 12b are
represented in Fig. 1 For 12a, the molecular ion M4þ is
observed at m/z ¼ 553.2 (calcd m/z ¼ 553.1) and M3þ
(M4þ þ PF6ꢀ) at m/z ¼ 785.6 (calcd m/z ¼ 785.8). Electro-
spray MS spectra of 12b shows the molecular ion M4þ at
m/z ¼ 565.5 (calcd m/z ¼ 565.6) and M3þ at m/z ¼ 802.3
(calcd m/z ¼ 802.5). Hexamers 4a and 4b were analysed by
Scheme 2 (a) (i) t-BuLi, OEt2 ; (ii) ZnCl2 , THF; (iii) bis(p-bromophenyl)acetylene, 5% PdCl2(PPh3)2 ; (iv) PTSA, CH2Cl2 , H2O (72%). (b) (i)
bis(p-tolyl)acetylene, t-BuOK, DMF; (ii) PTSA, CH2Cl2 , H2O (64%).
T h i s j o u r n a l i s Q T h e R o y a l S o c i e t y o f C h e m i s t r y a n d t h e
N e w . J . C h e m . , 2 0 0 4 , 2 8 , 5 8 5 – 5 9 4
586
C e n t r e N a t i o n a l d e l a R e c h e r c h e S c i e n t i f i q u e 2 0 0 4

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Scheme 3 (a) 10% Co2(CO)8 , dioxane, reflux. (b) 9, t-BuOK, THF.
FAB mass spectroscopy. In each case, molecular ions M4þ
,
For comparison, ferrocene (Fc), ferrocenecarboxaldehyde
(FcCHO) and compounds 13, 14 and 15 drawn in Scheme 6
M5þ, M6þ and M7þ were observed, as well as M3þ for 4a.
are also presented. For compounds 7a, 7b and 8a, 8b cyclic vol-
tammograms (CV) show a quasi-reversible one-electron oxida-
tion in which all the ferrocenes appear to be equivalent. For
these 4 compounds, the preparative electrolysis in aceto-
nitrile–dichloromethane mixtures gave very insoluble and
Mixed-valency properties
Results of cyclic voltammetry of compounds 7, 8 and BDT
fonctionalised molecules 1, 2 are presented in Table 1.
Scheme 4 (a) 10, NaH, THF, reflux. (b) (i) cis-RuCl2(bipy)2 or cis-RuCl2(bipy*)2 , EtOH, reflux; (ii) NH4PF6 .
T h i s j o u r n a l i s Q T h e R o y a l S o c i e t y o f C h e m i s t r y a n d t h e
C e n t r e N a t i o n a l d e l a R e c h e r c h e S c i e n t i f i q u e 2 0 0 4
N e w . J . C h e m . , 2 0 0 4 , 2 8 , 5 8 5 – 5 9 4
587

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Scheme 5 (a) 10% Co2(CO)8 , 1,2-dichloroethane–dioxane (4:1), 100 ꢁC.
unstable products, therefore the study of the oxidised forms by
absorption spectroscopy was impossible and our interest
turned to functionalised ferrocene molecules.
lower potential, proves that there is a strong interaction
between the ferrocene and BDT groups.
For compounds 1a and 2a (molecules without double
bonds), the first wave is reversible and mono-electronic while
the second oxidation leads to a strong adsorption onto the
electrode [Fig. 2(a)]. Alkyne 1b shows two well-resolved,
quasi-reversible and mono-electronic oxidation waves [Fig.
2(b)]. Complex 2b present two closed oxidation waves, which
correspond to multi-electronic transfers for which the number
of transferred electrons has not been determined. In the cases
of 1b and 2b the second oxidation can be unambiguously
attributed to a second ferrocene. Indeed, this wave cannot be
attributed to oxidation of BDT, which is irreversible and at
higher potential. Analysis by UV/Vis/NIR of the solution
By comparison of compounds 13 and 14, we can attribute
the first quasi-reversible and mono-electronic wave to the oxi-
dation of the ferrocenyl fragment. For 13 we observe a second
wave, irreversible and attributed to the BDT group, a result in
concordance with the work of Togni et al.17 who found that
compound 15 (Schema 6) shows an irreversible oxidation at
higher potentials (þ0.93 vs. SCE). The presence of the strong
donor BDT group on the ferrocene fragment in compound
13 causes a strong displacement of the first wave to lower
potential (nearly 800 mV) compared to 14. This result, com-
bined with the fact that the BDT group is also oxidised at
Fig. 1 Electrospray MS spectra of (a) 12a and (b) 12b.
T h i s j o u r n a l i s Q T h e R o y a l S o c i e t y o f C h e m i s t r y a n d t h e
C e n t r e N a t i o n a l d e l a R e c h e r c h e S c i e n t i f i q u e 2 0 0 4
588
N e w . J . C h e m . , 2 0 0 4 , 2 8 , 5 8 5 – 5 9 4

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oxidation potentials of the ferrocene and the ruthenium. How-
ever, the reduction waves of the bipy ligands become irreversi-
ble. These first electrochemical results indicate that there is no
electronic coupling between ferrocenes.
Table 1 Formal electrode potentials (in V vs. SCE) for the ferrocenyl
centred oxidation of ferrocene (Fc), ferrocenecarboxaldehyde
(FcCHO) and compounds 7, 8, 13, 14, 1 and 2a
Compound
E1/2 (1)/V
E1/2 (2)/V
DE/V
Fc
FcCHO
7a
0.5
0.83
–
–
Conclusions
–
–
0.85
0.8
–
–
We have synthesised three types of hexamers bearing 6 or 12
electro-active groups. Unfunctionalised hexamers 8a, 8b were
obtained in three steps from the chiral acetal 5. After a palla-
dium-catalysed cross-coupling reaction or a Siegrist condensa-
tion, the resulting alkynes were hydrolysed and cyclotrimerised
to give hexamers 8a, 8b. The second electro-active group can
be introduced either before the cyclotrimerisation reaction,
as in the case of the Rubipy fragment, or afterwards, as for
the BDT group. While the characterisation of compounds 1
and 2 can be done by NMR due to the complete symmetry
of the molecules, complexes 3 and 4 bearing the Rubipy frag-
ment were obtained as mixtures of diastereoisomers and char-
acterised using ESI-MS or FAB-MS techniques. All hexameric
compounds and the corresponding alkynes were studied by
cyclic voltammetry. The most interesting results are obtained
in the case of the alkynes and hexamers functionalised by the
BDT group (molecules 1 and 2). Indeed, in the case of mole-
cules with a double bond between the ferrocene and the phenyl
core (1b and 2b), we observe in the CVs two mono-electronic
oxidation waves (not well-resolved for 2b) corresponding to
the successive oxidation of two ferrocenes (for 2b, the number
of electrons involved in each oxidation has not been deter-
mined). At potentials between these two waves, MV complexes
exist and in the case of 2b, we observe an intervalence band in
the NIR that is characteristic of an electron transfer between
two electro-active centres. Efforts are now under way to try
to isolate MV complexes for a complete physical study.
7b
8a
–
–
0.84
0.67
–
–
8b
13
–
–
ꢀ0.4
0.42
0.34b
–
–
14
1a
–
ꢀ0.39
ꢀ0.42
ꢀ0.43
0.38
0.16c
0.18
0.03c
0.5
–
1b
2a
0.6
–
2b
0.12
a
Experimental conditions: CH2Cl2–CH3CN 2:1 (v:v), TBAP (0.1 M);
concentration in electro-active compound: 5 ꢂ 10ꢀ3 M; 2 mm2 glassy
carbon working electrode; SCE reference; 100 mV sꢀ1 sweep rate,
b
c
20 ꢁC. Irreversible Ep,ox
.
Adsorption Ep,ox .
obtained by preparative oxidation of 2b carried out at þ0.68 V
vs. SCE showed that the characteristic band at 450 nm of the
ferrocene disappears with the appearance of two new bands:
one at 550 nm that is characteristic of the ferricinium ion
and another band in the NIR at 1393 nm (Fig. 3). This second
band represents the intervalence band that corresponds to elec-
tron transfer between two electro-active centres of the VM
complex obtained by oxidation of complex 2b.
In Table 2 are presented the results of cyclic voltammetry
obtained for compounds 4, 11, 12 and the monomeric analo-
gues 16, 1718 (Scheme 7). These compounds show three regions
of electro-activity. (1) Between 0.4 and 0.5 V vs. SCE, we
observe the oxidation of the ferrocene, which is in all cases
reversible or quasi-reversible. (2) Between 1 and 1.3 V vs.
SCE the irreversible oxidation (irrev) of ruthenium(II) occurs.
(3) Between ꢀ1.4 and ꢀ2.2 V vs. SCE, the CVs show the reduc-
tion in three steps of the bipyridines (bipy) coordinated to the
ruthenium. In the mononuclear compounds 17a and 17b these
three reduction waves are completely reversible. Increasing the
number of electro-active centres causes almost no effect on the
Experimental
General methods
Melting points were determined on a Reichert apparatus. IR
spectra were recorded using a Perkin–Elmer FTIR 1600 spec-
trometer and are reported in wave numbers (cmꢀ1). UV-VIS
spectra were recorded on a Kontron spectrometer. Optical
Scheme 6 (a) 9, t-BuOK, THF (100%). (b) MeMgBr, OEt2 . (c) LiAlH4–AlCl3 , OEt2 (92% over two steps).
T h i s j o u r n a l i s Q T h e R o y a l S o c i e t y o f C h e m i s t r y a n d t h e
C e n t r e N a t i o n a l d e l a R e c h e r c h e S c i e n t i f i q u e 2 0 0 4
N e w . J . C h e m . , 2 0 0 4 , 2 8 , 5 8 5 – 5 9 4
589

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Fig. 2 CV curves of alkynes 1a (left) and 1b (right). In the case 1a, the adsorption at the electrode is characterised by a sharp peak. The scan rate is
100 mV sꢀ1
.
rotations were measured on a Perkin–Elmer 241 polarimeter.
1H and 13C NMR spectra were recorded on Brucker AC 200
(200 and 50 MHz) and AC 250 (250 and 63 MHz) machines.
Chemical shifts (d) are reported in ppm and coupling constants
(J) in Hz. As the internal reference, the solvent signal [1H:
d(CDCl3) ¼ 7.27; 13C: d(CDCl3) ¼ 77.0] was used. EI mass
spectra (70 eV) were measured on a Riberg Mag R10-10.
HR-MS and electrospray ionisation (ESI) mass spectra were
determined using a Finnigan MAT-95-S apparatus. FAB-MS
spectra were determined using a Finnigan MAT TSQ–70
equipped with a Xenon ION TECH 8 kV canon beam.
11 mmol, 22 ml). The solution was warmed to RT. and stirred
for 1 h. To the mixture was added PdCl2(PPh3)2 (0.5 mmol,
315 mg, 5%), followed by bis(4-bromophenyl)acetylene (4.5
mmol, 1.512 g). After being stirred at RT overnight the mix-
ture was treated with a saturated solution of ammonium chlor-
ide and extracted with Et2O. The organic phase was dried over
MgSO4 , the solvent evaporated, and the residue was purified
by column chromatography on silica gel (Et2O–cyclohexane
2:1). The diacetal was isolated as a light orange solid (2.6 g,
3.22 mmol, 72% yield). Mp 88 ꢁC, [a]D23 ꢀ471 (c 1, CHCl3);
1H NMR (CDCl3 , 250 MHz) d 1.47 (2H, m, CH2), 1.81
(2H, m, CH2), 3.36 (6H, s, CH3), 3.46 (4H, m, CH2–O), 3.96
(2H, m, CH2–O), 4.09 (10H, s, Cp), 4.29 (2H, m, Cpsubst.),
4.56 (2H, m, Cpsubst.), 4.58 (2H, m, Cpsubst.), 5.46 (2H, s,
O–CH–O), 7.46 (4H, d, J ¼ 8.1 Hz, aromatics), 7.65 (4H, d,
8.1 Hz, aromatics); 13C NMR (CDCl3 , 63 MHz) d 26.9,
27.8, 59.3, 67.0, 67.75, 67.9, 70.55, 71.05, 75.45, 76.1, 83.0,
85.95, 89.75, 99.9, 120.9, 129.0, 131.1, 139.0; HR-MS m/z
calcd for C46H46Fe2O6 : 806.1993; found: 806.2003.
THF and Et2O were distilled from Na/benzophenone,
DMF and acetonitrile from CaH2 , and CH2Cl2 from P2O5 .
All air- or moisture-sensitive reactions were carried out in
dry glassware under Ar. Flash column chromatography was
˚
performed employing 60 A C.C. 35–70 mm silica gel.
Syntheses
0
0
0
(RFc ,RFc )-1,2-Bis[4 -(a-formylferrocenyl)-1 -phenyl]acetyl-
ene, 7a. A solution of acetal 519 (10 mmol, 3.16 g) in dry
degassed diethyl ether (40 ml) was treated with a pentane solu-
tion of t-butyl lithium (1.6 M, 20 mmol, 14 ml) at ꢀ78 ꢁC for
10 min. The reaction was warmed to RT and stirred for 1 h. To
the resulting orange suspension was added at ꢀ78 ꢁC a freshly
prepared solution of anhydrous zinc chloride (0.5 M in THF,
The diacetal (3.22 mmol, 2.6 g) was dissolved in CH2Cl2 (70
ml). Water (30 ml) and p-toluenesulfonic acid (32.2 mmol, 6.2
g) were added and the mixture was stirred vigorously for 2 h at
RT. A saturated solution of NaHCO3 was added and the
organic phase was separated, dried over MgSO4 and concen-
trated. After filtration on silica gel (Et2O–CH2Cl2 1:1) and
recrystallisation from Et2O, the product 7a was isolated as
an orange solid (1.85 g, 3.2 mmol, 95% yield). Mp 108 ꢁC,
1
[a]2D3 þ341 (c 0.088, CHCl3); H NMR (CDCl3 , 200 MHz) d
4.24 (10H, s, Cp), 4.73 (2H, m, Cpsubst.), 4.86 (2H, m, Cpsubst.),
Table 2 Half-wave potentials (E1/2), oxidation potentials (Ep,ox) and
reduction potentials (Ep,red) of compounds 4, 11, 12, 16 and 17a
E1/2
Ep,ox
III
(Ru /Ru )/V
E1/2 or Ep,red
(bipy)/V
ꢃ
(Fc/Fcþ )/V
II
Compound
16
0.50
0.41
0.41
0.56
0.54
0.43
0.44
0.48
0.43
0.45
0.4
–
–
17a
17b
11a
11b
12a
12b
12c
12d
4a
1.21
1.18
–
ꢀ1.45 to ꢀ1.87b
ꢀ1.49 to ꢀ1.98b
–
–
–
1.20, 1.60
1.16
1.23
1.22
1.35, 1.65
1.23
ꢀ1.38 to ꢀ2c
ꢀ1.46 to ꢀ2c
ꢀ1.40 to ꢀ1.96c
ꢀ1.35 to ꢀ1.98c
c
ꢀ1.43 to ꢀ2
4b
ꢀ1.45 to ꢀ2c
a
Experimental conditions: CH2Cl2–CH3CN 2:1 (v:v), Et4NBF4 (0.1
M); concentration in electro-active compound: 5 ꢂ 10ꢀ3 M; 2 mm2
glassy carbon working electrode; SCE reference; 100 mV sꢀ1 sweep
b
c
rate, 20 ꢁC. Composed of 3 reversible waves. Composed of 3
Fig. 3 Intervalence band observed after preparative oxidation of
complex 2b.
irreversible waves.
T h i s j o u r n a l i s Q T h e R o y a l S o c i e t y o f C h e m i s t r y a n d t h e
C e n t r e N a t i o n a l d e l a R e c h e r c h e S c i e n t i f i q u e 2 0 0 4
590
N e w . J . C h e m . , 2 0 0 4 , 2 8 , 5 8 5 – 5 9 4

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140.15, 193.4; IR (CHCl3 , cmꢀ1) 1672 (CO); FAB-MS m/z
1963.1 (Mþ).
0
00 00
00
0
(RFc ,RFc )-1,2-Bis{4 -[a-(1 ,3 -benzodithiol-2 -ylferrocenyl)-
vinyl]-10-phenyl}acetylene, 1a. In a dry Schlenk tube were placed
the alkyne 7a (0.166 mmol, 100 mg) and the phosphonate 9
(0.498 mmol, 145 mg). THF (10 ml) was added and the solu-
tion cooled to 0 ꢁC before the slow addition of t-BuOK
(0.498 mmol, 56 mg) in 5 ml of THF. The heterogeneous solu-
tion was warmed to RT and stirred overnight. The mixture was
quenched with water at 0 ꢁC, extracted with CH2Cl2 and dried
over MgSO4 . After evaporation of the solvent, the crude reac-
tion mixture was purified by flash chromatography on silica
gel (diethyl ether–CH2Cl2 , 1:1). Monomer 1a was isolated as
an orange solid (100 mg, 69% yield). M.p. 105 ꢁC, [a]D23 þ900
(c 1, CHCl3); 1H NMR (CDCl3 , 200 MHz) d 3.94 (10H, s,
Cp), 4.23 (2H, t, J ¼ 2.6 Hz, Cpsubst.), 4.40 (2H, m, Cpsubst.),
4.64 (2H, m, Cpsubst.), 6.11 (2H, s, CH), 6.89–7.17 (16H, m,
aromatics); 13C NMR (CDCl3 , 63 MHz) d 66.95, 67.9,
69.35, 70.65, 81.3, 85.8, 89.85, 110.8, 121.0, 121.2, 121.6,
125.45, 125.75, 129.45, 129.55, 131.25, 135.45, 136.75, 138.75;
HR-MS m/z calcd for C50H34Fe2S4 : 874.0242; found:
874.0500.
0
00
000 000
000
0
(E,E,RFc ,RFc )-1,2-Bis(4 -{2 -[a-(1 ,3 -benzodithiol-2 -
ylferrocenylvinyl)]-100-vinyl}-10-phenyl)acetylene, 1b. Monomer
1b was synthesised using the same procedure as for 1a with
65 mg (0.1 mmol) of 7b and 3 equiv. of phosphonate 9 and
t-BuOK. Yield: 65%, m.p. (decomp.) > 220 ꢁC; [a]D23 þ853 (c
1
0.034, CHCl3); H NMR (CDCl3 , 250 MHz) d 4.14 (10H, s,
Cp), 4.44 (2H, br s, Cpsubst.), 4.65 (2H, br s, Cpsubst.), 4.81
(2H, br s, Cpsubst.), 6.35 (2H, s, CH), 6.72 (2H, d, J ¼ 15.6
Hz, Halkene), 6.90–7.50 (18H, m, aromatics þ Halkene); 13C
NMR (CDCl3 , 63 MHz) d 65.4, 66.3, 67.15, 70.75, 81.1,
89.15, 90.2, 110.15, 120.25, 121.0, 121.6, 125.5, 125.75,
125.75, 126.1, 126.35, 129.1, 130.1, 131.4, 131.9, 135.3,
136.74, 137.65, 138.3.
Scheme 7
5.00 (2H, m, Cpsubst.), 7.50 (8H, s, aromatics), 10.18 (2H, s,
CHO); 13C NMR (CDCl3 , 63 MHz) d 69.2, 71.25, 72.3,
89.95, 91.4, 122.0, 129.5, 131.45, 136.55, 192.7; IR (CHCl3 ,
cmꢀ1) 1662 (CO); MS (EI) m/z 121 (33%), 262 (30), 602 (M,
100%); HR-MS m/z calcd for C36H26Fe2O2 : 602.0632; found:
602.0631.
0
0
0
00
000
0000
00000
(RFc ,RFc ,RFc ,RFc ,RFc ,RFc )-Hexa{4-[a-(1 ,3 -
benzodithiol-20-ylferrocenylvinyl)]-1-phenyl}benzene, 2a. Cyclo-
trimer 2a was synthesised using the same procedure as for 1a
with 80 mg (0.0443 mmol) of 8a and 10 equiv. of phosphonate
9 and t-BuOK. Yield: 52%, m.p. 212 ꢁC, [a]D23 þ1747 (c 1,
CHCl3); 1H NMR (CDCl3 , 200 MHz) d 4.14 (30H, s, Cp),
4.41 (6H, t, J ¼ 2.5 Hz, Cpsubst.), 4.53 (6H, m, Cpsubst.), 4.83
(6H, m, Cpsubst.), 6.31 (6H, s, CH), 7.05–7.30 (24H, m, aro-
matics); 7.51 (24H, s, aromatics); 13C NMR (CDCl3 , 63
MHz) d 66.7, 67.45, 69.25, 70.55, 77.2, 81.1, 85.95, 111.8,
120.95, 121.4, 125.2, 125.5, 127.55, 128.7, 131.4, 135.1,
135.65, 136.9, 138.4, 140.35; FAB-MS m/z 2624.1 (Mþ, 8%),
1312.0 (M2þ, 30%).
0
00
000
0000
00000
(RFc ,RFc ,RFc ,RFc ,RFc ,RFc )-Hexa[4-(a-formylferro-
cenyl)-1-phenyl]benzene, 8a. A dry Schlenk tube was charged
with alkyne 7a (0.83 mmol, 500 mg) and Co2(CO)8 (0.083
mmol, 30 mg) under argon. Freshly distilled dioxane (10 ml)
was injected and the solution was refluxed overnight. After
evaporation of the solvent, the crude reaction mixture was
purified by flash chromatography on silica gel (diethyl
ether–cyclohexane–CH2Cl2 , 2:1:1). Cyclotrimer 8a was isola-
ted as an orange solid (425 mg, 85% yield). M.p. (decomp.)
> 250 ꢁC, [a]2D3 þ450 (c 0.1, CHCl3); 1H NMR (CDCl3 , 250
MHz) d 4.04 (30H, s, Cp), 4.56 (6H, m, Cpsubst.), 4.66 (6H,
m, Cpsubst.), 4.85 (6H, m, Cpsubst.), 6.91 (12H, d, J ¼ 7.7 Hz,
aromatics), 7.12 (12H, d, J ¼ 7.7 Hz, aromatics), 9.96 (6H,
s, CHO); 13C NMR (CDCl3 , 63 MHz) d 68.5, 71.05, 71.95,
74.55, 77.2, 91.9, 128.1, 131.25, 133.25, 139.45, 140.1, 193.65;
IR (CHCl3 , cmꢀ1) 1665.5 (CO); FAB-MS m/z 1807.2 (Mþ).
0
00 00
0
00
000
0000
00000
(RFc ,RFc ,RFc ,RFc ,RFc ,RFc )-Hexa(4-{(E)-2 -[a-(1 ,3 -
benzodithiol-200-ylferrocenylvinyl)]-10-vinyl}-1-phenyl)benzene,
2b. Cyclotrimer 2b was synthesised using the same procedure
as for 1a with 80 mg (0.041 mmol) of 8b and 10 equiv. of phos-
phonate 9 and t-BuOK. Yield: 88%, m.p. (decomp.) > 220 ꢁC,
1
[a]2D3 þ1240 (c 0.088, CHCl3); H NMR (CDCl3 , 250 MHz) d
0
4.06 (30H, s, Cp), 4.30 (6H, t, J ¼ 2.6 Hz, Cpsubst.), 4.51 (6H,
m, Cpsubst.), 4.63 (6H, m, Cpsubst.), 6.29 (6H, s, CH), 6.55 (6H,
d, 15.9 Hz, Halkene), 6.82 (6H, d, 15.9 Hz, Halkene), 6.86 (12H,
d, 8.1 Hz, aromatics), 6.99–7.22 (36 H, m, aromatics); 13C
NMR (CDCl3 , 63 MHz) d 65.1, 66.9, 68.3, 70.2, 81.75,
109.8, 120.95, 121.45, 123.85, 124.6, 125.3, 125.6, 127.6,
128.2, 129.0, 129.35, 131.85, 134.6, 135.5, 136.75, 139.5,
140.25.
0
00
000
0000
00000
(RFc ,RFc ,RFc ,RFc ,RFc ,RFc )-Hexa{(E)-4-[2 -(a-formyl-
ferrocenyl)10-vinyl]-1-phenyl}benzene, 8b. Cyclotrimer 8b was
synthesised using the same procedure as for 8a with 200 mg
(0.3 mmol) of 7b. Yield: 85%; m.p. (decomp.) > 250 ꢁC, [a]D23
1
ꢀ625 (c 0.064, CHCl3); H NMR (CDCl3 , 250 MHz) d 4.16
(30H, s, Cp), 4.57 (6H, t, J ¼ 2.5 Hz, Cpsubst.), 4.76 (6H, m,
Cpsubst.), 4.87 (6H, m, Cpsubst.), 6.63 (6H, d, J ¼ 16 Hz,
H
alkene), 6.85 (12H, d, J ¼ 8 Hz, aromatics), 7.05 (12H, d,
J ¼ 8 Hz, aromatics), 7.20 (6H, d, J ¼ 16 Hz, Halkene), 10.09
(6H, s, CHO); 13C NMR (CDCl3 , 63 MHz) d 70.1, 71.45,
72.55, 77.2, 86.4, 122.75, 124.9, 129.55, 131.7, 134.1, 139.85,
(RFc)-(a-p-Methoxyphenyl)-1,3-benzodithiol-2-ylferrocenyl-
vinyl, 13. This compound was synthesised using the same
T h i s j o u r n a l i s Q T h e R o y a l S o c i e t y o f C h e m i s t r y a n d t h e
C e n t r e N a t i o n a l d e l a R e c h e r c h e S c i e n t i f i q u e 2 0 0 4
N e w . J . C h e m . , 2 0 0 4 , 2 8 , 5 8 5 – 5 9 4
591

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(10:1) and the mixture was refluxed overnight. After cooling
procedure as for 1a with 200 mg (0.625 mmol) of (RFc)-
(a-p-methoxyphenyl)ferrocenecarboxaldehyde20 and 1.5 equiv.
of phosphonate 9 and t-BuOK. Yield: 100%, m.p. 126 ꢁC, [a]D23
to RT a saturated solution of NH4PF6 (1.315 mmol, 214 mg)
was added. After 10 min the red precipitate was filtered,
washed with water and ether and dried under vacuum. The
product was purified by flash chromatography (SiO2 , aceto-
nitrile–water–KNO3sat 47:2.5:0.5). The major fraction was iso-
lated, concentrated, and dissolved in a minimum volume of
acetonitrile, then precipitated by addition of a saturated solu-
tion of NH4PF6 . After filtration and washing, the product was
dried in vacuum overnight to give a red solid (300 mg, 87%
yield). M.p. (decomp.) > 250 ꢁC, 1H NMR (CD3CN/NaHSO3
in D2O, 200 MHz) d 1.39 (36 H, s, t-Bu), 2.55 (3H, s, Me), 4.18
(5H, s, Cp), 4.46 (2H, s, Cpsubst.), 4.62 (2H, s, Cpsubst.), 6.80
1
þ2209 (c 0.22, CHCl3); H NMR (CDCl3 , 200 MHz) d 3.83
(3H, s, Me), 4.13 (5H, s, Cp), 4.35 (1H, t, J ¼ 2.3 Hz, Cpsubst.),
4.45 (1H, br s, Cpsubst.), 4.79 (1H, br s, Cpsubst.), 6.27 (1H, s,
CH), 6.89 (2H, d, J ¼ 8.7 Hz, aromatics), 7.00–7.30 (4H, m,
aromatics), 7.44 (2H, d, J ¼ 8.7 Hz, aromatics); 13C NMR
(CDCl3 , 63 MHz) d 55.3, 66.2, 67.35, 69.25, 70.45, 81.1,
87.0, 111.35, 113.5, 120.9, 121.55, 125.4, 125.7, 128.7, 130.05,
130.7, 135.5, 136.85, 158.3; HR-MS m/z calcd for
C25H20FeOS2 : 456.0305; found: 456.0298.
(1H, d, J ¼ 16.1 Hz, Halkene), 7.20–7.70 (13H, m, Halkene
þ
(SFc)-(a-p-Methoxyphenyl)ethylferrocene, 14. To a solution
of (RFc)-(a-p-methoxyphenyl)ferrocenecarboxaldehyde (2
mmol, 640 mg) in 40 ml of diethyl ether at 0 ꢁC was slowly
added a 3 M solution of MeMgBr in diethyl ether (4 mmol,
1.33 ml). The reaction mixture was then warmed to RT and
stirred for 3 h. After hydrolysis, the organic phase was washed
with brine and dried over magnesium sulfate. The product was
purified by flash chromatography (SiO2 , diethyl ether) to give
670 mg (100%) of the alcohol as an orange oil.
H
bipy), 8.47 (6H, br s, Hbipy); 13C NMR (CD3CN/NaHSO3
in D2O, 63 MHz) d 21.0, 30.2, 36.05, 68.75, 70.25, 71.45,
81.7, 119.95, 121.45, 122.15, 124.0, 125.3, 128.9, 137.85,
141.3, 150.8, 151.25, 151.49, 151.5, 153.9, 157.6, 163.05; ESI-
MS m/z 509.2 (M2þ, 100%); 1163.3 (M2þ þ PF6ꢀ, 9%).
Bis(2,20-bipyridine)-(4-methyl-40-ferrocenylvinyl-2,20-bipyridi-
20
´
ne)ruthenium(II) dihexafluorophosphate, 17a . This complex
To a solution of AlCl3 (4 mmol, 533.5 mg) in 20 ml of
diethyl ether at 0 ꢁC was added LiAlH4 (6.6 mmol, 250.5 mg)
by portions; the mixture was warmed to RT and stirred for
1 h. The mixture was cooled again to 0 ꢁC and a solution of
the alcohol (2 mmol, 670 mg) in 20 ml of diethyl ether was
slowly added. The reaction mixture was warmed to RT and
stirred overnight. The reaction mixture was slowly added to
a mixture of ice and 2 M HCl. The product was extracted with
diethyl ether, washed with brine and dried over magnesium
sulfate. The product was purified by flash chromatography
(SiO2 , diethyl ether) to yield an orange solid (590 mg, 92%
yield). M.p. 60 ꢁC, [a]D23 ꢀ75 (c 0.466, CHCl3); 1H NMR
(CDCl3 , 250 MHz) d 1.18 (3H, t, J ¼ 7.4 Hz, CH3–CH2), 2.54
(2H, dq, 7.6 Hz, CH2–CH3), 3.82 (3H, s, O–CH3), 4.05 (5H, s,
Cp), 4.13 (1H, t, J ¼ 2.4 Hz, Cpsubst.), 4.18 (1H, t, J ¼ 2 Hz,
Cpsubst.), 4.32 (1H, t, J ¼ 2.1 Hz, Cpsubst.), 6.86 (2H, d,
J ¼ 8.7 Hz, aromatics), 7.45 (2H, d, J ¼ 8.7 Hz, aromatics);
13C NMR (CDCl3 , 63 MHz) d 14.85, 21.35, 55.2, 65.8,
67.65, 68.7, 69.75, 86.6, 88.75, 113.3, 130.0, 130.95, 157.85;
HR-MS m/z calcd for C19H20FeO: 320.0864; found: 320.0868.
was synthesised using the same procedure as for 17b from 16
(0.156 mmol, 60 mg), cis-dichlorobis(2,20-bipyridine)ruthe-
nium(II) (0.19 mmol, 92 mg), 10 ml of an ethanol–water
(10:1) mixture and NH4PF6 (0.347 mmol, 57 mg). After puri-
fication the complex 17a was isolated as a red powder (130
mg, 77% yield). M.p. (decomp.) > 250 ꢁC, 1H NMR (CD3CN,
250 MHz) d 2.55 (3H, s, CH3), 4.20 (5H, s, Cp), 4.48 (2H, br s,
Cpsubst.), 4.63 (2H, br s, Cpsubst.), 6.81 (1H, d, J ¼ 16.1 Hz,
Halkene), 7.25 (1H, d, J ¼ 5.1 Hz, Hbipy), 7.31 (1H, d, J ¼ 5.4
Hz, Hbipy), 7.40 (4H, m, Hbipy), 7.53 (2H, m, Hbipy), 7.58
(1H, d, J ¼ 16.1 Hz, Halkene), 7.74 (3H, m, Hbipy), 7.85 (1H,
d, J ¼ 5.1 Hz, Hbipy), 8.06 (4H, t, J ¼ 7.6 Hz, Hbipy), 8.48
and 8.51 (6H, 2 br s, Hbipy); 13C NMR (CD3CN, 63 MHz) d
21.25, 69.05, 70.5, 71.7, 120.65, 121.65, 124.15, 125.2, 126.0,
128.45, 129.15, 138.35, 128.6, 148.15, 151.4, 151.65, 152.3,
152.5, 152.6, 157.6, 157.9, 158.0, 165; ESI-MS m/z 397.0
(M2þ, 100%); 939.0 (M2þ þ PF6ꢀ, 14%).
0
00
000
0
(E,E,RFc ,RFc )-1,2-Bis{4 -[a-(4 -methyl-4 -vinyl-
200,2000-bipyridine)ferrocenyl]-10-phenyl}acetylene, 11a. This
compound was synthesised using the same procedure as for
16 with 430 mg of 7a (0.72 mmol), 4 equiv. of phosphine oxide
(2.86 mmol, 460 mg) and 16 equiv. of NaH (11.5 mmol, 276
(E)-4-Methyl-40-ferrocenylvinyl-2,20-bipyridine, 1621. To a
suspension of NaH (6 mmol, 144 mg) in 5 ml of THF was
added slowly a mixture of ferrocenecarboxaldehyde (0.87
mmol, 186 mg) and phosphine oxide 10 (1.15 mmol, 436 mg)
in 20 ml of THF; the mixture was heated at reflux overnight.
After cooling to RT the reaction mixture is cautiously hydro-
lysed at 0 ꢁC with 10 ml of water, then the product was
extracted with dichloromethane and dried over magnesium
sulfate. The product was purified by flash chromatography
(SiO2 , ethyl acetate) to give a red solid (260 mg, 78% yield).
M.p. 173 ꢁC, 1H NMR (CDCl3 , 250 MHz) d 2.43 (3H, s,
CH3), 4.13 (5H, s, Cp), 4.34 (2H, AA0XX0 system, J ¼ 1.7
Hz, Cpsubst.), 4.49 (2H, AA0XX0 system, J ¼ 1.7 Hz, Cpsubst.),
6.68 (1H, d, J ¼ 16.1 Hz, Halkene), 7.14 (1H, d, J ¼ 5 Hz, H5),
1
mg). Yield: 82%, m.p. 144 ꢁC, [a]D23 þ848 (c 0.25, CHCl3), H
NMR (CDCl3 , 200 MHz) d 2.43 (6H, s, CH3), 4.13 (10H, s,
Cp), 4.49 (2H, t, J ¼ 2.2 Hz, Cpsubst.), 4.65 (2H, br s, Cpsubst.),
4.77 (2H, br s, Cpsubst.), 6.83 (2H, d, J ¼ 16.1 Hz, Halkene), 7.14
0
and 7.32 (4H, 2 d, J ¼ 4.8 and 5.1 Hz, H5,5 ), 7.45 (2H, d,
J ¼ 16.1 Hz, Halkene), 7.55 (8H, s, aromatics), 8.23 and 8.36
0
0
(4H, 2 br s, H3,3 ), 8.57 (4H, 2 d, J ¼ 4.8 and 5.1 Hz, H6,6 );
13C NMR (CDCl3 , 63 MHz) d 21.2, 65.2, 69.05, 70.95, 71.7,
80.05, 87.95, 89.9, 118.2, 119.95, 121.4, 122.05, 124.75, 124.8,
129.45, 131.05, 131.4, 138.45, 146.05, 148.15, 148.9, 149.4,
155.95, 156.7. HR-MS m/z calcd for C60H46Fe2N4 :
934.2421; found: 934.2425.
0
7.26 (1H, d, J ¼ 4.8 Hz, H5 ), 7.27 (1H, d, J ¼ 16.1 Hz,
0
H
alkene), 8.23 and 8.41 (2H, 2 br s, H3,3 ), 8.56 (2H, 2 d, J ¼ 5.1
0
00
000
(E,E,E,E,RFc ,RFc )-1,2-Bis(4 -{2 -[a-(4 -methyl-40000-vinyl-
2000,20000-bipyridine)ferrocenyl]-100-vinyl}-10-phenyl)acetylene, 11b.
This compound was synthesised using the same procedure as
for 16 with 327 mg of 7b (0.5 mmol), 4 equiv. of phosphine
oxide (1.5 mmol, 576 mg) and 16 equiv. of NaH (6 mmol,
144 mg). Yield: 85%, m.p. 115 ꢁC, [a]D23 þ250 (c 0.1, CHCl3);
1H NMR (CDCl3 , 200 MHz) d 2.48 (6H, s, Me), 4.14 (10H,
s, Cp), 4.53 (2H, m, Cpsubst.), 4.78 (4H, m, Cpsubst.), 6.80
(2H, d, J ¼ 16 Hz, Halkene), 6.81 (2H, d, J ¼ 15.9 Hz, Halkene),
0
and 4.8 Hz, H6,6 ); 13C NMR (CDCl3 , 63 MHz) d 21.15,
67.4, 69.35, 69.75, 81.65, 117.3, 120.35, 122.0, 123.3, 124.7,
132.6, 146.1, 148.15, 148.85, 149.45, 156.0, 156.45; HR-MS
m/z calcd for C23H20FeN2 : 380.0976; found: 380.0945.
0
Bis(4,40-di-tert-butyl-2,20-bipyridine)-(4-methyl-40-ferrocenyl-
vinyl-2,20-bipyridine)ruthenium(II) dihexafluorophosphate, 17b.
The ligand 16 (0.263 mmol, 100 mg) and cis-dichlorobis(4,40-
di-tert-butyl-2,20-bipyridine)ruthenium(II) (0.395 mmol, 280
mg) were dissolved in 16.5 ml of a mixture of ethanol–water
0
7.15–7.25 (4H, m, Halkene þ H5or5 ), 7.38 (2H, d, J ¼ 5 Hz,
0
H
5or5 ), 7.52 (8H, s, aromatics); 7.56 (2H, d, J ¼ 16 Hz,
T h i s j o u r n a l i s Q T h e R o y a l S o c i e t y o f C h e m i s t r y a n d t h e
C e n t r e N a t i o n a l d e l a R e c h e r c h e S c i e n t i f i q u e 2 0 0 4
592
N e w . J . C h e m . , 2 0 0 4 , 2 8 , 5 8 5 – 5 9 4

View Article Online
70.9, 71.85, 73.2, 79.95, 89.0, 90.3, 120.8, 121.65, 123.0,
124.2, 124.9, 125.75, 128.2, 129.0, 130.45, 132.0, 136.05,
138.35, 139.5, 147.55, 151.1, 151.35, 151.8, 152.35, 157.25,
157.65, 157.75; ESI-MS m/z 440.1 (M4þ, 23%); 635.8 (M4þ þ
PF6ꢀ, 100%); 1026.1 (M4þ þ 2PF6ꢀ, 67%); 2197.1 1 (M4þ þ
3PF6ꢀ, 3%).
0
Halkene), 8.34 and 8.57 (4H, 2 s, H3,3 ), 8.62 (4H, 2 d, J ¼ 4.7
and 5 Hz, H6,6 ); 13C NMR (CDCl3 , 63 MHz) d 21.15, 66.8,
0
66.9, 69.9, 70.55, 81.15, 83.1, 90.55, 117.6, 120.45, 121.75,
122.1, 124.75, 125.5, 125.95, 127.15, 130.3, 131.9, 137.45,
146.0, 148.2, 148.85, 149.45, 155.9, 156.55; HR-MS m/z calcd
for C64H50Fe2N4 : 986.2734; found: 986.2738.
Complex 12d. This complex was synthesised using the same
procedure as for 12a from 11b (0.061 mmol, 60 mg), cis-
dichlorobis(2,20-bipyridine)ruthenium(II) (0.152 mmol, 74
mg), 15 ml of ethanol–water (10:1) and NH4PF6 (0.61 mmol,
100 mg). After purification the complex 12d was isolated as a
red powder (47 mg, 32% yield). M.p. (decomp.) > 250 ꢁC,
Complex 12a. The product 11a (0.2 mmol, 187 mg) and cis-
dichlorobis(4,40-di-tert-butyl-2,20-bipyridine)ruthenium(II) (0.6
mmol, 431 mg) were dissolved in 44 ml of ethanol–water
(10:1) and the mixture was refluxed overnight. After cooling
to RT a saturated solution of NH4PF6 (1 mmol, 163 mg)
was added. After 10 min the red precipitate was filtered,
washed with water and ether and dried under vacuum. The
product was purified by flash chromatography (SiO2 , aceto-
nitrile–water–KNO3sat 47:2.5:0.5). The major fraction was
isolated, concentrated, dissolved in a minimum volume of
acetonitrile and then precipitated by addition of a saturated
solution of NH4PF6 . After filtration and washing, the product
was dried in vacuum overnight to give a red solid (210 mg, 38%
yield). M.p. (decomp.) > 250 ꢁC, [a]D23 þ818 (c 0.044, CH3CN);
1H NMR (CD3CN/NaHSO3 in D2O, 250 MHz) d 1.39 (72 H,
s, t-Bu), 2.53 (6H, s, Me), 4.17 (10H, 2 s, Cp), 4.64 (2H, br,
Cpsubst.), 4.80 (2H, br s, Cpsubst.), 4.92 (2H, br s, Cpsubst.), 6.94
(2H, d, J ¼ 15.5 Hz, Halkene), 7.23 (2H, d, J ¼ 5.5 Hz, Hbipy),
7.25–7.75 (32 H, m, aromatics þ Halkene þ Hbipy), 8.46 (12H, s,
1
[a]2D3 þ361 (c 0.036, CH3CN); H NMR (CD3CN, 200 MHz)
d 2.58 (6H, s, Me), 4.17 (10H, 2 s, Cp), 4.66 (2H, br s, Cpsubst.),
4.91 (2H, br s, Cpsubst.), 4.97 (2H, br s, Cpsubst.), 6.92 (2H, d,
J ¼ 16.2 Hz, Halkene), 6.94 (2H, d, J ¼ 16 Hz, Halkene), 7.15–
7.95 (36H, m, aromatics þ Halkene þ Hbipy), 8.06 (8H, t,
J ¼ 7.4 Hz, Hbipy), 8.54 (12H, m, Hbipy); 13C NMR (CD3CN,
63 MHz) d 21.0, 21.2, 61.75, 67.5, 68.2, 71.45, 81.1, 84.7, 89.45,
90.7, 120.6, 122.05, 122.65, 124.3, 124.85, 125.7, 126.85,
127.45, 128.2, 128.95, 130.05, 131.9, 132.4, 135.6, 138.3,
139.7, 147.6, 151.1, 151.35, 151.8, 152.2, 152.3, 157.25, 157.7
ESI-MS m/z 505 (100%); 1155 (80%).
Cyclotrimer 4a. A dry Schlenk tube was charged with com-
plex 12a (0.036 mmol, 100 mg) and Co2(CO)8 (0.0036 mmol,
1.3 mg) under argon. Freshly distilled 1,2-dichloroethane (4
ml) and dioxane (1 ml) were injected and the solution was
refluxed for 12 h. After evaporation of the solvent, the crude
reaction mixture was purified by flash chromatography
(SiO2 , acetonitrile–water–KNO3sat 47:2.5:0.5). The major frac-
tion was isolated, concentrated, dissolved in a minimum
volume of acetonitrile and precipitated by addition of a satu-
rated solution of NH4PF6 . After filtration and washing, the
product was dried in vacuum overnight to give a red solid
(70 mg, 70% yield). M.p. (decomp.) > 300 ꢁC, [a]D23 þ1438 (c
0.016, CHCl3). 1H NMR (CD3CN/NaHSO3 in D2O, 250
MHz) d 1.43 (216H, br s, t-Bu), 2.64 (18H, br s, CH3), 3.70–
4.10 (36H, m, Cp þ 1 Cpsubst.), 4.30 (6H, m, Cpsubst.), 4.55
(6H, m, Cpsubst.), 6.67 (8H, m), 6.87 (6H, m), 7.12 (18H, br
s), 7.20–7.70 (50H, m), 8.20 and 8.26 (4H, 2 br s), 8.49 (22H,
br s); FAB-MS m/z 2649.3 (M3þ, 13%, calcd. 2648.1), 1950.6
H
bipy); 13C NMR (CD3CN/NaHSO3 in D2O, 63 MHz) d
21.05, 30.25, 36.05, 67.5, 70.65, 71.8, 74.6, 78.05, 80.05,
86.55, 89.5, 120.85, 122.2, 123.0, 124.0, 124.2, 125.3, 125.7,
129.0, 129.45, 130.2, 130.4, 130.6, 132.05, 132.3, 135.0,
147.25, 150.75, 151.55, 157.6, 164.0; ESI-MS m/z 553.2
(M4þ, 20%); 785.6 (M4þ þ PF6ꢀ, 100%).
Complex 12b. This complex was synthesised using the same
procedure as for 12a from 11b (0.056 mmol, 56 mg),
cis-dichlorobis(4,40-di-tert-butyl-2,20-bipyridine)ruthenium(II)
(0.14 mmol, 100 mg), 11 ml of a ethanol–water (10:1) and
NH4PF6 (0.28 mmol, 46 mg). After purification complex 12b
was isolated as a red powder (70 mg, 44% yield). M.p.
1
(decomp.) > 250 ꢁC, [a]D23 þ250 (c 0.016, CH3CN); H NMR
(CD3CN/NaHSO3 in D2O, 200 MHz) d 1.43 (72H, s, t-Bu),
2.60 (6H, s, Me), 4.18 (10H, s, Cp), 4.68 (2H, t, J ¼ 2.5 Hz,
Cpsubst.), 4.92 (2H, m, Cpsubst.), 4.98 (2H, m, Cpsubst.), 6.94
(2H, d, J ¼ 15.9 Hz, Halkene), 6.96 (2H, d, J ¼ 16 Hz, Halkene),
7.27 (2H, d, J ¼ 6.2 Hz, Hbipy), 7.30–7.75 (32H, m, aroma-
tics þ Halkene þ Hbipy), 7.87 (2H, d, J ¼ 16.2 Hz, Halkene),
8.49 (8H, s, Hbipy), 8.54 (2H, s, Hbipy), 8.60 (2H, s, Hbipy);
13C NMR (CD3CN/NaHSO3 in D2O, 63 MHz) d 21.05,
30.2, 36.0, 67.55, 68.3, 71.5, 71.8, 81.25, 84.7, 90.95, 120.55,
122.0, 122.1, 122.8, 124.25, 125.3, 126.75, 126.95, 127.5,
128.95, 132.5, 135.4, 138.9, 147.35, 150.75, 151.2, 151.5,
157.5, 157.6, 157.85, 163.05; ESI-MS m/z 565.5 (M4þ, 21%);
802.3 (M4þ þ PF6ꢀ, 100%).
(M4þ
, , 67%, calcd.
100%, calcd. 1949.8), 1531.4 (M5þ
1530.9), 1251.5 (M6þ, 32%, calcd. 1251.6), 1052.8 (M7þ, 4%,
calcd. 1052.1).
Cyclotrimer 4b. This complex was synthesised using the
same procedure as for 4a with 75 mg of 12b (0.026 mmol) with
Co2(CO)8 (0.0026 mmol, 0.9 mg). After purification complex
4b was isolated as a red powder (40 mg, 53% yield). M.p.
1
(decomp.) > 300 ꢁC, [a]D23 þ2500 (c 0.006, CHCl3); H NMR
(CD3CN/NaHSO3 in D2O, 200 MHz) d 1.40 (216 H, br s,
t-Bu), 2.59 (18H, s, CH3), 3.98 (30H, s, Cp), 4.38 (6H, m,
Cpsubst.), 4.67 (6H, m, Cpsubst.), 4.75 (6H, m, Cpsubst.), 6.55–
7.70 (94 H, m), 8.47 (26H, s); FAB-MS m/z 1986.9 (M4þ
,
Complex 12c. This complex was synthesised using the same
procedure as for 12a from 11a (0.107 mmol, 100 mg), cis-
dichlorobis(2,20-bipyridine)ruthenium(II) (0.268 mmol, 130
mg), 22 ml of ethanol–water (10:1) and NH4PF6 (1.07 mmol,
175 mg). After purification the complex 12c was isolated as a
red powder (90 mg, 36% yield). m.p. (decomp.) > 250 ꢁC,
[a]2D3 þ694 (c 0.11, CH3CN); 1H NMR (CD3CN, 200 MHz)
d 2.54 and 2.58 (6H, 2 s, Me), 4.17 and 4.18 (10H, 2 s, Cp),
4.66 (2H, t, J ¼ 2.5 Hz, Cpsubst.), 4.83 (2H, m, Cpsubst.), 4.97
(2H, m, Cpsubst.), 7.09 (2H, d, J ¼ 16 Hz, Halkene), 7.38 (2H,
d, J ¼ 6 Hz, Hbipy), 7.40–7.70 (20H, m, aromatics þ Hbipy),
7.78 (2H, d, J ¼ 6.1 Hz, Hbipy), 7.79 (2H, d, J ¼ 16.1 Hz,
62%, calcd. 1987.3), 1561.5 (M5þ, 100%, calcd. 1560.9),
1277.4 (M6þ, 65%, calcd. 1276.6), 1075.1 (M7þ, 20%, calcd.
1073.5).
Cyclic voltammetry
Cyclic voltammetry measurements were carried out in dry and
oxygen-free solvents (CH2Cl2 and acetonitrile) with 0.1 M
tetrabutylammonium perchlorate (TBAP) or tetraethyl-
ammonium tetrafluoroborate (Et4NBF4) as the supporting
electrolyte and with ꢄ0.001 M substrate under a nitrogen inert
gas atmosphere. A conventional three-electrode setup was used
with a platinum disk working electrode and an Ag/AgCl
pseudo-reference electrode. Digital simulation of the CVs for
H
alkene), 7.83 (2H, d, J ¼ 5.7 Hz, Hbipy), 8.03 (6H, m, Hbipy),
8.10–8.25 (12H, m, Hbipy), 8.67 (2H, s, Hbipy), 8.79 (6H, m,
bipy); 13C NMR (CD3CN, 63 MHz) d 21.0, 30.2, 67.45,
H
T h i s j o u r n a l i s Q T h e R o y a l S o c i e t y o f C h e m i s t r y a n d t h e
C e n t r e N a t i o n a l d e l a R e c h e r c h e S c i e n t i f i q u e 2 0 0 4
N e w . J . C h e m . , 2 0 0 4 , 2 8 , 5 8 5 – 5 9 4
593

View Article Online
9
S. Barlow and D. O’Hare, Chem. Rev., 1997, 97, 637 and refer-
ences therein.
10 (a) C. M. Csado, I. Cuadrado, M. Moran, B. Alonso, B. Garcıa,
some products was done with the kinetic program COOL (pro-
vided by EG & G Priceton Applied Research, Oak Ridge, TN,
USA).
´
´
´
B. Gonzalez and J. Losada, Coord. Chem. Rev., 1999, 185–186, 53
and references therein; (b) R. P. Kingsborough and T. M. Swager,
Prog. Inorg. Chem., 1999, 48, 123 and references therein; (c) R.
Deschenaux, E. Serrano and A.-M. Levelut, Chem. Commun.,
1997, 1577; (d ) R. Schneider, C. Ko¨llner, I. Weber and A. Togni,
Chem. Commun., 1999, 2415; (e) K. J. Watson, J. Zhu, S. T.
Nguyen and C. A. Mirkin, J. Am. Chem. Soc., 1999, 121, 462;
( f ) K. J. Watson, J. Zhu, S. T. Nguyen and C. A. Mirkin, J.
Organomet. Chem., 2000, 606, 79; (g) S. Nlate, J. Ruiz, V. Sartor,
R. Navarro, J.-C. Blais and D. Astruc, Chem.-Eur. J., 2000, 6,
2544.
Acknowledgements
´
The CNRS and Universite Paris-Sud are acknowledged for
financial support. V.M. thanks MRES for a fellowship. The
authors also want to thank A. Spote and R. Rosenberg
´
(Universite Catholique de Louvain) for help in measurements
of FAB-MS spectra.
11 For multiferrocenyl systems with other linkers, see, for example:
(a) J.-L. Fillault, J. Linares and D. Astruc, Angew. Chem., Int.
Ed. Engl., 1994, 33, 2460; (b) J.-L. Fillault and D. Astruc, New
J. Chem., 1996, 20, 945; (c) C. Patoux, C. Coudret, J.-P. Launay,
C. Joachim and A. Gourdon, Inorg. Chem., 1997, 36, 5037; (d )
R. Deschenaux, F. Monnet, E. Serrano, F. Turpin and A.-M.
Levelut, Helv. Chim. Acta, 1998, 81, 2072; (e) C. Ko¨llner, B. Pugin
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and P. H. Dixneuf, Angew. Chem., Int. Ed., 1998, 37, 1714;
(g) A. Ta´rraga, P. Molina, D. Curiel and M. D. Velasco, Organo-
metallics, 2001, 20, 2145.
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