Preparation of polymers containing Fe(0)-coordinated 2,5-diethynylsilole units

Article abstract of DOI:10.1016/j.ica.2005.01.017

UV irradiation of poly(organosilanylene-2,5-diethynylenesiloles) in benzene with an excess of Fe(CO)₅ led to the formation of Fe(CO) ₃-coordinated silole units in the polymer backbone. The Fe(CO) ₃-coordinated polymers exh

Full text of DOI:10.1016/j.ica.2005.01.017

Inorganica Chimica Acta 358 (2005) 4156–4162
www.elsevier.com/locate/ica
Preparation of polymers containing Fe(0)-coordinated
2,5-diethynylsilole units
a,
a
a
a
Joji Ohshita *, Hidekazu Arase , Tomohisa Sumida , Nobuhisa Mimura ,
a
a
b
a
Kazuhiro Yoshimoto , Yosuke Tada , Yoshihito Kunugi , Yutaka Harima ,
,a
*
Atsutaka Kunai
a
Department of Applied Chemistry, Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima 739-8527, Japan
b
Division of Materials Science, Faculty of Integrated Arts and Sciences, Hiroshima University, Higashi-Hiroshima 739-8521, Japan
Received 12 November 2004; accepted 21 January 2005
Available online 17 February 2005
Dedicated to Professor H. Schmidbaur.
Abstract
UV irradiation of poly(organosilanylene-2,5-diethynylenesiloles) in benzene with an excess of Fe(CO)5 led to the formation of
Fe(CO)3-coordinated silole units in the polymer backbone. The Fe(CO)3-coordinated polymers exhibited suppressed p-conjugation,
relative to the parent non-coordinated polymers. Hole-transporting properties of poly(organosilanylene-2,5-diethynylenesiloles)
were examined by the performance of EL devices containing the polymer layer as the hole-transport and Alq3 layer as the elec-
tron-transporting emitter.
ꢀ 2005 Elsevier B.V. All rights reserved.
Keywords: Silole; Silicon polymer; Iron carbonyl complex; Hole transport; EL device
1. Introduction
mers have been published to date. In addition, it is noted
that silole derivatives may be potential ligands to transi-
tion-metal-center [3]. Corriu et al. [4] have previously
reported the formation of polymers having Fe(CO)3-
coordinated silole-1,1-diyl units. However, no other
studies about the incorporation of metal-coordination
to the silole ring in polymeric systems have appeared un-
til recently when we have reported the synthesis of
Fe(CO)3-coordinated poly(disilanylene-3,4-diethynyl-
enesiloles) (1b in Scheme 1) [5]. As expected, the coordi-
nation of Fe(CO)3 to the 3,4-diethynylsilole unit leads to
significant changes in the polymer electronic states and
the UV absorptions move to longer wave length from
those of the parent non-coordinated polymers (1a), indi-
cating the enhancement of p-conjugation by the
Fe(CO)3-coordination. This is probably due to the in-
crease of the bond order between silole C3–C4 atoms,
Current interest has been focused on the chemistry of
a silole ring system, because of their unique electronic
states. The characteristic red-shifted UV absorptions
of silole derivatives would arise from their low-lying
LUMO due to the r*–p* interaction between the silicon
r-orbital and the butadiene p-orbital [1,2]. The low-
lying LUMO provides the chance to use silole derivatives
as the functionality materials, such as semi-conductors
and electron-transporting materials, and many papers
concerning the synthesis and functionalities of mono-
meric silole derivatives as well as silole-containing poly-
*
Corresponding authors. Tel.: +81824247743; fax: +81824245494.
E-mail addresses: jo@hiroshima-u.ac.jp (J. Ohshita), akunai@
hiroshima-u.ac.jp (A. Kunai).
0020-1693/$ - see front matter ꢀ 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2005.01.017

J. Ohshita et al. / Inorganica Chimica Acta 358 (2005) 4156–4162
4157
R
R
Ph
Me
Ph
Ph
Si Si
+
Fe(CO)5
H
SiPhMe2
Ph
Br
Br
Si
R
R
Me3Si
Me
SiMe3
Me
Si
n
R = Me, Et
Ph
Me
1a
PdCl2(PPh3)2, CuI
NEt3
R
R
R R
Fe(CO)3
Me2PhSi
SiPhMe2
Si
Ph
Si Si
Si Si
R
R
R R
2a
Me3Si
Me
Me3Si
Me
SiMe3
Me
SiMe3
Me
Si
Si
x
y
Fe(CO)3
Ph
1b
Ph
Scheme 1.
Fe(CO)5
Me2PhSi
SiPhMe2
Si
∆
Me
Ph
through which the two ethynyl groups may be conju-
gated more effectively.
2b
To know how the regional change affects the
electronic states of Fe(CO)3-coordinated diethynylsil-
ole-containing polymers, we synthesized Fe(CO)3-coor-
dinated 2,5-diethynylsilole polymers by the reactions
of poly(organosilanylene-2,5-diethynylenesiloles) [6]
and Fe(CO)5, and studied their properties in comparison
with those of the 3,4-diethynylsilole polymers [5]. The
preparation of poly(organosilanylene-2,5-diethynylene-
siloles) has been previously reported.
Scheme 2.
Me
Ph
Si
Si
Ph
Me
Fe
Fe
Polymers having an alternate arrangement of organo-
silanylene and p-conjugated units have been studied as
novel functionality materials [8,9]. In order to elucidate
the present organosilanylene-2,5-diethynylenesilole
alternating polymers as the hole-transport, we fabricated
double-layer EL devices with the structure of ITO/poly-
mer film/Alq3/Mg–Ag (ITO = indium tin oxide, Alq3 =
(tris(8-quinolinolato)aluminum (III))) and examined
their performance.
endo
exo
Chart 1.
42.9 and 91.8 ppm, which are characteristics of a me-
tal-coordinated butadiene unit [10]. On the other hand,
the signals of sp carbons of 2b appeared at 108.0 and
110.6 ppm, in essentially the same region as those of
the starting 2a, indicating that no significant interaction
takes place between the ethynyl units and Fe-complex
center in 2b, similar to polymer 1b [5].
2. Results and discussion
UV spectral data for 2a and 2b are summarized in Ta-
ble 1, together with those of Fe(CO)3-corrdinated and
non-coordinated 3,4-diethynylsilole derivatives reported
previously (3a and 3b in Chart 2) [5]. Compound 2a
exhibited red-shifted absorptions relative to 3a.
Fe(CO)3-coordination to 2,5-diethynylsilole system in
2b led to blue-shifts of the absorption maxima, in
marked contrast to 3,4-diethynylsilole 3a, whose absorp-
tion maxima are red-shifted by Fe(CO)3-coordination.
2.1. Preparation of a model compound
First, we examined a model reaction of 2,5-bis[(dim-
ethylphenylsilyl)ethynyl]-1-methyl-1,3,4-triphenylsilole
(2a) with Fe(CO)5 (Scheme 2). Thus, heating a xylene
solution of compound 2a at 150 ꢁC for 20 h with an ex-
cess of Fe(CO)5 gave Fe(CO)3-coordinated diethynylsil-
ole (2b) in 66% yield. Compound 2b was isolated as the
single stereoisomer probably with the exo-configuration
with respect to the Fe-coordinated silole unit (Chart 1).
Table 1
UV spectral data for Fe-coordinated and non-coordinated diethynyl-
siloles in THF
1
Although the H and 13C NMR spectra of the reaction
mixture indicated the existence of the endo-isomer, that
was removed by recrystallization. The ratio of isomers in
the reaction mixture was determined approximately to
be exo/endo = 3/1 by the NMR spectra.
The structure of 2b was verified by spectroscopic and
elemental analysis. The 13C NMR spectrum of 2b
showed a carbonyl signal at 209.2 ppm and signals at
Compound
kmax (nm)
kedge (nm)
2a
2b
3a
3b
210, 283, 398
460
450
390
430
210, 259 (sha), 307 (sha)
210, 268, 301
210, 237, 320
a
Shoulder.

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J. Ohshita et al. / Inorganica Chimica Acta 358 (2005) 4156–4162
of a 4-fold excess of Fe(CO)5 in benzene, only insoluble
Me
Me
SiMe3
Me
Me3Si
Me
Si
Si
SiMe3
dark-brown solids were formed and no soluble products
were isolated from the reaction mixture. Although the IR
spectrum of the insoluble products showed absorptions
at 1984 and 2050 cmÀ1, due to the stretching frequencies
of the carbonyl ligands, no further information to char-
acterize the products could be obtained.
Me3Si
Fe(CO)3
Et2Si
Et2Si
SiEt2
SiEt2
Et2Si
Et2Si
SiEt2
SiEt2
Next, we examined the reaction of 4a with Fe(CO)5
under photochemical conditions (Scheme 3). Thus, irra-
diation of a benzene solution of 4a with 8 equiv of
Fe(CO)5 with a high-pressure mercury lamp bearing a
Pyrex filter for 2 h gave a dark brown mixture contain-
ing insoluble precipitates. After filtration of the precipi-
tates, the soluble products were reprecipitated from
benzene–methanol to give an Fe(CO)3-coordinated
Fe(CO)3
SiMe3
Me
Me3Si
Me
SiMe3
Me
Me3Si
Si
Si
Me
3a
3b
Ph
Ph
Ph
Bu
Si
1
polymer (4b) in 79% yield. The H NMR spectrum of
4b revealed two MeSi signals of Fe(CO)3-coordinated
silole ring at 0.39 and 1.31 ppm, in an integral ratio of
3/1, probably due to exo- and endo-silole units, respec-
tively (Chart 1). Its 13C NMR spectrum also showed
two sets of signals due to Fe(CO)3-coordinated exo-
and endo-1-methyl-1,3,4-triphenylsilole units in the same
region as those of the model compound 2b. The degree
of the introduction of Fe(CO)3-coordination to the
polymer was calculated to be x/y = 10/90, by the integra-
Si
n
Ph
Bu
6a
Chart 2.
Presumably, the coordination in 2b decreases the p-bond
order of C2–C3 and C4–C5, relative to those in 2a, to
suppress the conjugation in the 2,5-diethynylsilole unit.
1
tion of the H NMR signals.
2.2. Preparation of Fe(CO)3-coordinated 2,5-
diethynylsilole polymers
Table 2 summarizes the properties of polymers 4a
and 4b. The molecular weight of polymer 4b was smaller
than that calculated on the basis of the molecular weight
of the starting 4a. Probably, the higher molecular weight
fraction of polymer 4a was removed as the insoluble pre-
cipitates from the reaction mixture. Photochemical
cleavage of the Si–Si bond may also be involved in this
reaction [8]. UV spectrum of 4b clearly indicated the de-
crease of the absorbancy of the band at about 415 nm,
To obtain polymers with Fe(CO)3-coordinated 2,5-
diethynylsilole units, we first carried out the reaction of
poly[tetraethyldisilanylene-(2,5-diethynylene-1-methyl-
1,3,4-triphenylsilole)] (4a) with Fe(CO)5 under the same
conditions as those for the preparation of 2b. However,
when 4a was heated at 150 ꢁC for 20 h in the presence
Ph
Me
Ph
Ph
R
Si
R
+
H
H
Br
Br
Si
m
Ph
Ph
R
PdCl2(PPh3)2, CuI
NEt3
Si
Si
Me
Ph
m
n
R
4a R = Et, m = 2
5a R = Bu, m = 1
Fe(CO)3
Ph
Ph
Ph
Ph
Ph
Ph
R
R
Fe(CO)5
Si
Si
Si
Si
hν
m
m
y
x
Me
Me
R
R
4b R = Et, m = 2
5b R = Bu, m = 1
Scheme 3.

J. Ohshita et al. / Inorganica Chimica Acta 358 (2005) 4156–4162
4159
Table 2
Properties of Fe-coordinated and non-coordinated 2,5-diethynylsilole-
polymers
cating that thermal liberation of the Fe(CO)3-units oc-
curred during the analysis. Similar decrease in the Td5
value by Fe(CO)3-coordination was also observed for
polymer 1b when compared with 1a [5]. However, there
can be seen no significant increase in the weight loss at
1000 ꢁC for polymers 4b and 5b relative to 4a and 5a.
Polymer Mw (Mw/Mn)a kmax (nm) (e)b Td5 (ꢁC)c wt. loss (%)d
4a
4b
5a
5b
a
21000 (2.4)
11000 (2.5)
31000 (3.2)
7100 (2.7)
415 (6800)
413 (2000)
406 (5900)
405 (1700)
418
214
421
220
45
47
40
55
2.3. Applications of poly(organosilanylene-2,5-
diethynylenesilole)s to hole-transports in EL devices
Determined by GPC, relative to polystyrene standards.
In THF.
Temperature resulting in 5% weight loss noted by thermogravi-
b
c
Double layer EL devices having a spin-coated film of
polymers 4a and 5a as the hole-transport and vapor-
deposited layer of Alq3 as the electron-transporting
emitter were fabricated. Fig. 2 represents the current
metric analysis of the polymer at the rate of 10 ꢁC/min in a nitrogen
atmosphere.
d
Weight loss at 1000 ꢁC based on the initial weight.
which may be due to a blue shift in the absorption max-
imum of Fe-coordinated segments in the polymer chain.
The IR band due to the C„C stretching moved to high-
er energy from 2109 to 2120 cmÀ1 by Fe-coordination,
again indicating the suppressed conjugation between
the Fe-coordinated silole and ethynylene units in 4b.
Similar to 4b, Fe(CO)3-coordinated monosilanylene
polymer 5b was prepared from 5a in 57% yield, whose
properties are also summarized in Table 2. Although
polymer 5b was barely soluble in organic solvents and
we could not carry out the NMR spectroscopy, the IR
and UV spectra closely resemble those of 4b (Fig. 1).
The IR spectrum revealed an absorption due to the
C„C stretching at slightly higher energy from that of
5a, together with the C@O stretching bands. Further-
more, the carbon and hydrogen contents determined
by combustion elemental analysis are in good agreement
with the calculated values of polymer 5b whose silole
units are wholly coordinated with an Fe(CO)3-unit.
Polymer 6a (see Chart 2) [6] having two phenyl groups
on the silole silicon atom did not react with Fe(CO)5 un-
der both thermal and photochemical conditions. In
these reactions, polymer 6a was recovered unchanged.
The temperatures resulting in 5% weight loss of the
initial weight (Td5) were noted by thermogravimetric
analysis (TGA) of the polymers in a nitrogen atmo-
sphere. As listed in Table 2, the Fe(CO)3-coordination
resulted in a significant decrease in the Td5 value, indi-
Fig. 2. Current density–voltage (top) and luminescence–voltage plots
(bottom) for EL devices having a polymer film of (h) 4a and ( ) 5a,
as the hole-transport.
ꢀ
Fig. 1. UV spectra of polymers 5a and 5b.

4160
J. Ohshita et al. / Inorganica Chimica Acta 358 (2005) 4156–4162
density–voltage (I–V) and luminance–voltage (L–V)
plots of the devices. As can be seen in Fig. 2, the device
with polymer 5a showed lower turn-on voltage than that
with 4a, and always afforded higher current density and
luminance in the applied voltage of 6–16 V with the
maximum luminance of 300 cd/m2. This is in contrast
to the fact that polymer 4a exhibited the UV kmax at
lower energy than 5a, and may be due to the higher con-
centration of p-conjugated unit in the film of monosilan-
ylene polymer 5a. Similar tendency was observed for
other organosilanylene-p-electron system alternating
polymers [8,11].
tography eluting with hexane to give a crude product.
Recrystallization of the crude product from hexane gave
0.25 g (37% yield) of 2a in pure form as the yellow sol-
1
ids; m.p.: 93–95 ꢁC. H NMR (CDCl3): d 0.34 (s, 12H),
0.75 (s, 3H), 7.11–7.25 (m, 25H). 13C{1H}NMR
(CDCl3): d 5.9, 0.7, 103.4, 106.7, 116.9, 122.6, 127.2,
127.6, 127.7, 128.2, 129.1, 129.3, 130.3, 133.7, 134.6,
137.2, 163.7 (one carbon is overlapping). Anal. Calc.
for C43H40Si3: C, 80.56; H, 6.29. Found: C, 80.46; H,
6.02%.
4.3. Preparation of 2b
A mixture of 89 mg (0.24 mmol) of 2a and 0.109 g
(0.555 mmol) of Fe(CO)5 in 1.3 mL of xylene was heated
at 150 ꢁC for 20 h, in a sealed glass tube. The resulting
insoluble materials were filtered and the solvent was
evaporated. The residue was subjected to preparative
GPC eluting with benzene to give a crude product.
Recrystallization of the crude product from ethanol
gave 30 mg (66% yield) of compound 2b in pure form
3. Conclusions
On the basis of the results described above, we dem-
onstrated that 2,5-diethynylsilole unit may be used as
the potential ligands to transition metal center, unless
they have two sterically bulky substituents at the silole
silicon atom. The coordination of the Fe(CO)3-unit to
diethynylsilole system seems to provide an opportunity
to modify the electronic states of the p-electron system.
Thus, Fe(CO)3 -coordination to 2,5-diethynylsilole unit
led to suppressed conjugation in this system, in contrast
to 3,4-diethynylsilole system whose coordination with
Fe(CO)3 enhances the conjugation between the ethynyl
groups through the silole p-system. In addition, we
found that the present silole-containing polymers 4a
and 5a may be used as the hole-transport for EL devices.
1
as the pale brown solids; m.p.: 126–128 ꢁC. H NMR
(CDCl3): d 0.36 (s, 12H), 1.26 (s, 3H), 7.25–7.52 (m,
25H). 13C{1H}NMR (CDCl3): d À5.2, À0.7, 42.9,
91.8, 108.0, 110.6, 127.4, 127.6, 128.1, 129.0, 129.8,
131.8, 132.6, 133.4, 133.6, 135.2, 137.5, 139.7, 209.2.
Anal. Calc. for C46H40FeO3Si3: C, 70.75; H, 5.16.
Found: C, 70.52; H, 5.13%.
The NMR spectra of the reaction mixture indicated
the formation of the other isomer of 2b, which was re-
1
moved by recrystallization. H NMR (CDCl3): d 0.06
(s, 3H), 0.38 (s, 12H), 7.11–7.57 (m, 25H, overlapping
with the signals of 2b). 13C{1H}NMR (CDCl3): d 1.0,
6.1, 41.4, 91.6, 108.7, 127.7, 128.0, 128.2, 129.1, 130.3,
133.6, 133.7, 133.8, 134.1, 137.5, 208.4, signals of other
carbons may overlap with those of 2b.
4. Experimental
4.1. General procedures
All reactions were carried out under an atmosphere
of dry nitrogen. Benzene and xylene were dried over so-
dium–potassium alloy and sodium, respectively, and dis-
tilled just before use. Triethylamine was distilled from
potassium hydroxide and stored over activated molecu-
lar sieves 4A before use. The starting compounds,
2,5-dibromo-1-methyl-1,3,4-triphenylsilole [12], ethynyl-
dimethylphenylsilane [13], and 1,1,2,2-tetraethyldiethy-
nyldisilane [14] were prepared as reported in the literature.
4.4. Preparation of dibutyldiethynylsilane
A solution of 0.40 mol of ethylmagnesium bromide in
350 mL of THF was added slowly to 400 mL of THF
saturated with acetylene over a period of 4 h, to prepare
ethynylmagnesium bromide. To the resulting solution of
ethynylmagnesium bromide, which may contain a small
amount of ethynylenedimagnesium dibromide, was
added 10.64 g (0.05 mol) of dibutyldichlorosilane and
the mixture was stirred at room temperature for 20 h.
After hydrolysis with water, organic layer was separated
and the aqueous layer was extracted with ether. The or-
ganic layer and the extracts were combined and dried
over anhydrous magnesium sulfate. Evaporation of the
solvent and distillation of the residue under reduced
pressure gave 8.82 g (92% yield) of dibutyldiethynylsi-
lane; b.p.: 105–106 ꢁC (23 mmHg). IR: 3290,
4.2. Preparation of 2a
A mixture of 0.50 g (1.04 mmol) of 2,5-dibromo-1-
methyl-1,3,4-triphenylsilole, 40 mg of PdCl2(PPh3)2,
6 mg of CuI, and 25 mL of triethylamine was stirred
at room temperature for 30 min. To this was added
0.66 g (4.15 mmol) of ethynyldimethylphenylsilane and
the mixture was heated under reflux for 15 h. The result-
ing salts were filtered and the solvent was evaporated.
The residue was subjected to silica gel column chroma-
2027 cmÀ1 1H NMR (CDCl3): d 0.71–0.77 (m, 4H),
.

J. Ohshita et al. / Inorganica Chimica Acta 358 (2005) 4156–4162
4161
0.89 (t, 6H, J = 6.9 Hz), 1.31–1.50 (m, 8H), 2.46 (s, 2H).
13C{1H}NMR (CDCl3): d 13.6, 13.8, 25.5, 25.9, 84.7,
95.0. MS m/z 192 (M+). Anal. Calc. for C12H20Si: C,
74.92; H, 10.48. Found: C, 75.22; H, 10.17%.
polymer). IR: 2121, 2051, 1986 cmÀ1. Anal. Calc. for
(C36H38FeO3Si2)n: C, 69.93; H, 5.56. Found: C, 69.88;
H, 5.90%.
4.7. Preparation of EL devices
4.5. Preparation of 4a and 5a
A thin film (ca 70 nm) of polymer 4a or 5a was pre-
pared by spin coating from the chloroform solution on
an anode, indium–tin-oxide (ITO) coated on a glass sub-
strate (Nippon Sheet Glass Co.). An electron-transport-
ing-emitting layer was then prepared by vacuum
deposition of Alq3 at 1 · 10À5 Torr with a thickness of
60–70 nm on the polymer film. Finally, a layer of mag-
nesium–silver alloy with an atomic ratio of 10:1 was
deposited on the Alq layer surface as the top electrode
at 1 · 10À5 Torr.
A mixture of 0.48 g (1.00 mmol) of 2,5-dibromo-1-
methyl-1,3,4-triphenylsilole, 34 mg of PdCl2(PPh3)2,
6 mg of CuI, and 12 mL of triethylamine was stirred
at room temperature for 30 min. To this was added
0.22 g (1.00 mmol) of tetraethyl-1,2-diethynyldisilane
and the mixture was stirred at 50 ꢁC for 48 h. The result-
ing salts were filtered and the solvent was evaporated.
Reprecipitation of the residue from benzene/methanol
gave 0.397 g (73% yield) of 4a; m.p.: 79–86 ꢁC. IR:
2109 cmÀ1 1H NMR (CDCl3): d 0.58–1.16 (23H, Et
.
and Me), 7.08–7.81 (15H). 13C{1H} NMR (CDCl3): d
À5.9, 5.0, 8.3, 102.8, 108.3, 122.6, 127.1, 127.4, 128.0,
129.2, 130.2, 132.1, 134.5, 137.2, 162.7 (silole C2 and
C5). Anal. Calc. for (C35H38Si3)n: C, 77.42; H, 7.05.
Found: C, 76.23; H, 7.00%.
Acknowledgements
This work was supported by a Grant-in-Aid for Sci-
entific Research (B) (No. 16350102) from the Ministry
of Education, Science, Sports and Culture of Japan,
and NEDO (Project No. 01A26005a), to which our
thanks are due. We thank Sankyo Kasei Co. Ltd., Tok-
uyama Co. Ltd. for financial support.
Polymer 5a was obtained in the same fashion as
above using tetraethyl-1,2-diethynyldisilane in place of
dibutyldiethynylsilane in 69% yield; m.p.: 85–91 ꢁC.
1
IR: 2116 cmÀ1. H NMR (C6D6): d 0.69–1.31 (m, 21H,
Bu and Me), 7.08–7.81 (m, 15H, Ph). 13C{1H}NMR
(C6D6): d À5.7, 13.8, 14.9, 25.9, 26.0, 101.5, 106.0,
122.5, 127.1, 127.6, 128.1, 129.3, 130.3, 131.9, 134.6,
137.1, 163.6 (silole C2 and C5). Anal. Calc. for
(C35H36Si2)n: C, 81.97; H, 7.08. Found: C, 80.38; H,
6.99%.
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4.6. Preparation of 4b and 5b
A mixture of 150 mg (0.28 mmol) of 4a and 0.433 g
(2.20 mmol) of Fe(CO)5 in 30 mL of benzene was irradi-
ated with a high pressure mercury lamp (100 W) bearing
a Pyrex filter with water-cooling for 2 h. The resulting
insoluble materials were filtered and the solvent was
evaporated. Reprecipitation of the residue from ben-
zene/methanol gave 0.149 g (79% yield) of 4b as the dark
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(C6D6): d 0.39 (br s, 0.7H, exo-Me), 0.80–1.11 (m, 20.3
H, Et, overlapping with the Et and Me signals of Fe-
non-coordinated units), 1.31 (br s, 2H, endo-Me),
7.00–7.65 (m, 15H, Ph, overlapping with the signals of
Fe-non-cordinated units). 13C{1H}NMR (C6D6): d
À4.9, À6.2, 5.4, 8.7, 42.7, 44.4, 91.1, 91.6, 103.1, 110.8,
127.8, 128.9, 129.1, 129.5, 129.7, 130.2, 130.8, 131.0,
132.1, 132.7, 133.9, 134.1, 134.6, 135.0, 135.8, 137.8 (Sig-
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Anal. Calc. for (C38H38FeO3Si3)0.9n(C35H38Si3)0.1n: C,
67.77; H, 5.73. Found: C, 66.79; H, 5.68%.
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Polymer 5b was obtained from 5a in the same fashion
as above in 57% yield (calculated as a wholly substituted
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4162
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