Reaction of organocobalt polymers with isocyanide. Synthesis of novel poly[(η5-cyclopentadieny1)(η 5-amino-cyclopentadieny1)-cobalticinium-diyl-alt-biphenyl-4,4′- diyl]s

Article abstract of DOI:10.1016/S0022-328X(00)00393-4

On the basis of the fact that the reaction of a cobaltacyclopentadiene derivative with t-butyl isocyanide quite effectively provides a (η⁵-cyclopentadienyl)(η ⁴-iminocyclopentadiene)cobalt derivative which reveals a unique solvatochromic behavior, the polymers having cobaltacyclopentadiene-diyl and biphenyl-4,4′-diyl repeating units 1 were subjected to the reaction with t-butyl isocyanide to give those having (η⁵-cyclopentadienyl)(η ⁴-iminocyclopentadiene)cobalt moieties in the main chain 2. By the subsequent reaction with iodomethane, the polymers 2 were converted quantitatively into cobalticinium-containing polymers 3 (i.e. poly[(η⁵-cyclopentadienyl)(η ⁵-amino-cyclopentadienyl)cobalticinium-diyl-alt-biphenyl-4,4′- diyl)]s). The results of the spectroscopic, the electrochemical, and thermal analyses of the polymers (2 and 3) are also described.

Full text of DOI:10.1016/S0022-328X(00)00393-4

www.elsevier.nl/locate/jorganchem
Journal of Organometallic Chemistry 611 (2000) 570–576
Reaction of organocobalt polymers with isocyanide. Synthesis of
novel poly[(h5-cyclopentadienyl)(h5-amino-cyclopentadienyl)-
cobalticinium-diyl-alt-biphenyl-4,4%-diyl)]s
Ikuyoshi Tomita* a,1, Jong-Chan Lee b, Takeshi Endo* b,2
a Department of Electronic Chemistry, Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology,
4259 Nagatsuta, Midori-ku, Yokohama 226-8502, Japan
b Research Laboratories of Resources Utilization, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan
Received 3 March 2000; accepted 26 March 2000
Abstract
On the basis of the fact that the reaction of a cobaltacyclopentadiene derivative with t-butyl isocyanide quite effectively
provides a (h5-cyclopentadienyl)(h4-iminocyclopentadiene)cobalt derivative which reveals a unique solvatochromic behavior, the
polymers having cobaltacyclopentadiene-diyl and biphenyl-4,4%-diyl repeating units 1 were subjected to the reaction with t-butyl
isocyanide to give those having (h5-cyclopentadienyl)(h4-iminocyclopentadiene)cobalt moieties in the main chain 2. By the
subsequent reaction with iodomethane, the polymers 2 were converted quantitatively into cobalticinium-containing polymers 3
(i.e. poly[(h5-cyclopentadienyl)(h5-amino-cyclopentadienyl)cobalticinium-diyl-alt-biphenyl-4,4%-diyl)]s). The results of the spectro-
scopic, the electrochemical, and thermal analyses of the polymers (2 and 3) are also described. © 2000 Elsevier Science S.A. All
rights reserved.
Keywords: Organometallic polymer; Reactive polymer; Polymer reaction; Cobaltacyclopentadiene; Cobalticinium; Isocyanide; Solvatochromism
examples demonstrate that the organocobalt polymers
1 are quite powerful intermediates leading to the func-
1. Introduction
tional polymers possessing various main chain struc-
tures. Namely, they can be regarded as a new type of
main chain reactive polymers.
Polymers having organometallic repeating units are
potentially of importance as reactive and functional
materials with advanced features. On the basis of the
reports of Yamazaki et al. that cobaltacyclopentadiene
derivatives are useful intermediates leading to many
useful organic molecules with versatile functional
groups [1], we have reported the synthesis and reactions
of organocobalt polymers having cobaltacyclopentadi-
ene moieties in the main chain 1. That is, the reaction
of (h5-cyclopentadienyl)bis(triphenylphosphine)cobalt
complex and diyne monomers provides the
organocobalt polymers 1 [2] and their reactions with
isocyanates, nitriles, sulfur, etc., give rise to polymers
possessing various main chain structures [3]. These
Besides the applications of 1 as a precursor for
organic polymers, they are also potentially of impor-
tance as a precursor of organometallic polymers with
different organometallic centers. For example, the
organocobalt polymers 1 could be converted to cy-
clobutadienecobalt-containing polymers by the rear-
rangement reaction [4]. By using (or developing) the
reactions of the cobaltacyclopentadiene derivatives
providing novel organometallic complexes, a new type
of organometallic polymers revealing unique functions
might be produced from the organocobalt polymers 1
[5]. According to Yamazaki et al., the cobaltacyclopen-
tadiene derivatives are reported to be converted to
(h5 - cyclopentadienyl)(h4 - iminocyclopentadiene)cobalt
complexes by the reaction with isocyanides and the
resulting complexes undertake an alkylation to give
1 *Corresponding author. Fax:
tomita@echem.titeh.ac.jp.
+81-45-9245489; e-mail:
2 *Corresponding author.
0022-328X/00/$ - see front matter © 2000 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(00)00393-4

I. Tomita et al. / Journal of Organometallic Chemistry 611 (2000) 570–576
571
Scheme 1.
Scheme 2.
Fig. 1. 1H-NMR spectra of 5 in C6D6 (a), 5% in C6D6+CD3OD (b),
and 7 in C6D6+CD3OD (c) (*1: C6D6, *2: CD3OD).
(h5-cyclopentadienyl)(h5-aminocyclopentadienyl)cobal-
ticinium derivatives [6a]. Therefore, the reaction of the
cobaltacyclopentadiene moieties in the organocobalt
Yamazaki et al. [6a], the reaction of a (h5-cyclopenta-
dienyl)(triphenylphosphine)cobaltacyclopentadiene de-
rivative 4 with t-butyl isocyanide was re-investigated to
confirm the quite effective nature of the reaction. That
is, an iminocyclopentadiene-cobalt complex 5 was
obtained in 88% yield as black crystals by recrystalliza-
tion from n-hexane–benzene. The reaction did not
provide any side products such as a cyclobutadiene-
cobalt 6 via the rearrangement of 4. In benzene, 5
was converted quantitatively to a derivative of cobal-
ticinium iodide 7 by the reaction with iodomethane,
while the alkylation did not take place in a MeOH
solution (Scheme 2).
polymer
1
with isocyanides may provide the
organometallic polymers bearing (h5-cyclopentadi-
enyl)(h4-iminocyclopentadiene)cobalt moieties as a re-
peating unit 2 and the subsequent treatment of 2 with
alkyl halides is expected to give polymers bearing
(h5-cyclopentadienyl)(h5-aminocyclopentadienyl)cobal-
ticinium moieties 3 (Scheme 1). The polymers (2 and 3)
might serve as a new type of poly(metallocene)s that
might reveal interesting properties.
We describe herein the results on the reaction of the
organocobalt polymers 1 with an isocyanide followed
by the alkylation, and the electrochemical and the
thermal properties of the resulting polymers are also
discussed.
The complex 5 revealed unique solvatochromism.
That is, 5 dissolves in benzene to form a purple-colored
solution which turns to red in (or by the addition of)
MeOH. This color change is a reversible process and
can be observed not only in MeOH but also in aprotic
polar solvents such as tetrahydrofuran and N,N-
2. Results and discussion
2.1. Synthesis and physical properties of the model
compounds 5 and 7
1
dimethylformamide. In the H-NMR spectrum of 5 in
C6D6 (Fig. 1(a)), a singlet peak at l 4.68 and that at
1.28 ppm attributable to the cyclopentadienyl (Cp) and
to the t-butylimino groups, respectively, were observed.
In order to clarify the efficiency of the reaction of the
cobaltacyclopentadienes with isocyanides reported by

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I. Tomita et al. / Journal of Organometallic Chemistry 611 (2000) 570–576
1
these results, 5 was supposed to have a zwitterionic
character (5%) in polar solvents. This behavior might
originate from the equilibrium between 5 and 5% whose
distribution depends upon the character of the solvents.
The hypothesis of the zwitterionic structure of 5 was
also supported by IR spectra. The peak attributable to
the CꢀN stretching was observed at 1584 cm−1 in the
solid state (KBr disk) which disappeared when mea-
sured in a MeOH solution.
UV–vis spectra of 5 (both in benzene and MeOH)
and 7 (in MeOH) are shown in Fig. 2. Compared to the
case of 5 in benzene (umax=400 nm), umax of 5% in
MeOH shifted to the longer wavelength by 10 nm,
probably because of the more ionic character of the
complex in MeOH. In the case of 7, the corresponding
umax was observed at 484 nm.
In the H-NMR spectrum of 5 in a mixed solvent of
C6D6 and CD3OD (Fig. 1(b)), the peak of the Cp
shifted to the lower field by 0.73 ppm and the peak of
t-butylimino group shifted to the higher field by 0.28
ppm [7]. The difference was also observable in the
13C-NMR spectra. In the mixed solvent of C6D6 and
CD3OD, the peaks of the Cp and of the t-butylimino
groups were found at 87.31 and 30.09 ppm, respec-
tively, which were lower by 3.0 and higher by 2.1 ppm,
respectively, than those taken in C6D6. Judging from
2.2. Polymer reactions
The organocobalt polymer 1a [8] was subjected to the
reaction with t-butyl isocyanide under the same condi-
tions to the model experiments. The reaction proceeded
homogeneously and a powdery polymer 2a was ob-
tained in 90% yield by the precipitation with n-hexane
under nitrogen. Similar to the case of the model com-
pound 5, 2a also revealed solvatochromism depending
upon the solvents. The polymer 2a was relatively un-
stable under air to be converted to an insoluble mate-
rial [9]. When the alkylation of 2a was carried out in
situ (i.e. 2a obtained from 1a was subjected to the
reaction with an excess of iodomethane without isola-
tion), an air-stable polymer having cobalticinium units
3a was obtained.
Fig. 2. UV–vis absorption spectra of 5 (5×10−5 M benzene solu-
tion), 5% (5×10−5 M methanol solution), and 7 (5×10−5
M
methanol solution).
The structure of the obtained polymers (2a and 3a)
1
was confirmed by H-, 13C-NMR, and IR spectra. In
1
the H-NMR spectrum of the polymer 2a (Fig. 3(a)),
two peaks attributable to the Cp originated from those
of the iminocyclopentadienecobalt and the cyclobutadi-
enecobalt units were observed at 4.65–4.85 and 4.50–
4.60 ppm, respectively. The peak of the t-butyl group
also appeared at 1.20–1.50 ppm. From the integral
ratio of the Cps, the polymer 2a was found to contain
ca. 85% of the iminocyclopentadiene cobalt units. In
the case of a mixed solvent of C6D6 and CD3OD (Fig.
3(b)), peaks of the Cps were observed at 5.50–5.70 and
at 4.50–4.60 ppm (those of the iminocyclopentadienyl-
cobalt and of the cyclobutadienecobalt units, respec-
tively), in which the former peak shifted to lower field
by ca. 0.85 ppm. Besides, the peak of the t-butyl group
shifted to higher field by ca. 0.3 ppm in accordance
with the proposed zwitterionic structure of the iminocy-
clopentadienecobalt units 2a%. In the 1H-NMR spec-
trum of 3a (Fig. 3(c)), a new peak attributable to the
methyl group was observed at 2.60–2.80 ppm and the
integral ratio of the Cps and the methyl group made it
possible to determine the unit ratio of aminocyclo-
Fig. 3. 1H-NMR spectra of 2a in C6D6 (a), 2a% in C6D6+CD3OD (b),
and 3a in C6D6+CD3OD (c) (*1: C6D6, *2: n-hexane, and *3:
CD3OD).

I. Tomita et al. / Journal of Organometallic Chemistry 611 (2000) 570–576
573
Table 1
Synthesis of cobalticinium-containing polymers (3) a
1
3
b
b
Reactant
a:b
Mn (Mw/Mn) c
Product
Yield (%)
k:l:m
1a
85:15
80:20
80:20
6800 (1.5)
22 600 (1.6)
9100 (1.3)
3a
3b
3c
96 d
81 e
96 e
70:15:15
65:20:15
55:25:20
1b
1c f
a The reaction of 1 with t-butyl isocyanide was carried out in benzene at 70°C for 1 day under N2. Without isolation of the resulting
iminocyclopentadienecobalt-containing polymers, the reaction with iodomethane was carried out at r.t. for 1 day under N2.
b Determined by 1H-NMR.
c Estimated by GPC (THF, PSt standard).
d Isolated yield by the precipitation with benzene.
e Isolated yield by the precipitation with MeOH.
f 1c was reacted with t-butyl isocyanide for 3 days and then the reaction with iodomethane was also carried out for 3 days.
pentadienyl cobalticinium:iminocyclopentadienecobalt:
cyclobutadienecobalt units in 3a to be ca. 70:15:15.
The organocobalt polymer bearing electron-donating
groups 1b and that bearing electron-withdrawing
groups 1c were also subjected to the reaction with
t-butyl isocyanide followed by the treatment with
the polymer 3a exhibited two reversible oxidation peaks
at 0.28 and 0.64 V, a quasi-reversible reduction at
−0.8 V, and two irreversible reductions at −1.57 and
−1.77 V (Fig. 5(b,c)). In the case of 3a, the current of
the first oxidation is dependent upon the redox history
where the peak intensity became stronger when the
measurement was started from the reduction side. The
increased oxidation current might be originated from
oxidation of the cobalt moieties and the higher voltage
shift of the oxidation might be due to the stabilization
of the reduced form of cobalticinium moiety in the
polymer 3a in comparison with that of 7.
The thermal properties of the iminocyclopentadiene-
cobalt- and cobalticinium-containing polymers (2a and
3a, respectively), were estimated by thermogravimetric
analyses (TGA) (Fig. 6). The 10% weight loss (Td10) of
2a and 3a was observed at 453 and 364°C, respectively,
while the organocobalt polymer 1a had Td10 at 240°C
[11]. The degradation of 2a and 3a below 500°C might
be originated from the decomposition of the lateral
alkyl moieties because their weight losses observed at
500°C are approximately equal to the weights of their
soft segments.
iodomethane,
from
which
the
corresponding
cobalticinium-containing polymers (3b and 3c) were
obtained in 81 and 96% yields, respectively, by the
precipitation with MeOH (Table 1). From their 1H-
NMR spectra, the unit ratios were found to be ca.
65:20:15 and 55:25:20, respectively. These results indi-
cate that the conversion of 1 to 2 proceeds quantita-
tively. However, the following alkylation does not
occur in a quantitative fashion, most probably because
the polymers produced by the alkylation have ionic
structures and their solubility in the reaction system
was not sufficient [10].
2.3. Physical properties of polymers
UV–vis spectra of the cobalticinium-containing poly-
mer 3a and its model compound 7 are shown in Fig. 4.
The two absorption maxima at 334 and 484 nm were
observed in a benzene–MeOH solution of 7. The corre-
sponding absorption bands could be also observed in
the case of 3a, although the intensity of the absorption
at longer wavelength was relatively weaker, simply be-
cause of the density of the cobalticinium units in 3a (ca.
70% of the repeating units of 3a has the cobalticinium
structure).
The redox behavior of the cobalticinium compound 7
and the polymer 3a was examined by cyclic voltamme-
try, using a 1 mM–0.1 M Bu4NBF4–CH3CN solution
and precast film in 0.1 M Bu4NBF4–CH3CN on a Pt
electrode, respectively, at the scan rate of 50 mVs−1
(Fig. 5). In the case of 7 (Fig. 5(a)), the cyclic voltam-
mogram (CV) revealed four reversible redox potentials
at −1.73, −0.82, 0.28, and 0.63 V versus SCE, while
Fig. 4. UV–vis absorption spectra of 7 (5×10−5 M methanol
solution) and 3a (5×10−5 M methanol–benzene (v/v=50/50) solu-
tion).

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I. Tomita et al. / Journal of Organometallic Chemistry 611 (2000) 570–576
recorder at a scanning rate of 50 mVs−1. The working,
auxiliary, and reference electrodes were 1 cm2 Pt plate,
2 cm2 Pt plate, and SCE, respectively. A 0.1 M acetoni-
trile solution of Bu4NBF4 was used as electrolyte. Ther-
mogravimetric analyses (TGA) were carried out on a
Seiko TG/DTA 220 instrument at a heating rate of
10°C min−1 under nitrogen.
Organocobalt polymers 1a–1c [2c] and a cobaltacy-
clopentadiene 4 [1a] were obtained as previously de-
scribed. t-Butyl isocyanide was prepared according to
the literature procedure [12]. Benzene was dried over
sodium and distilled under nitrogen. Iodomethane and
other reagents were used as received.
3.1. Synthesis of (p5-cyclopentadienyl)(p4-N-t-
butyliminotetra-phenylcyclopentadiene)cobalt (5)
To a test tube were added 4 (1.486 g, 2.00 mmol), five
equivalents of t-butyl isocyanide (1 ml, 10 mmol), and
benzene (15 ml) under nitrogen and the mixture was
kept stirring at 70°C for 1 day. After the reaction, the
product 5 was obtained in 88% yield as black crystals
by recrystallization from n-hexane. From the remaining
solution after the recrystallization, no side product such
as 6 nor the starting 4 was detected.
Fig. 5. CVs of 7 as a 1 mM–0.1 M Bu4NBF4–CH3CN solution (a)
and 3a as a precast film immersed in 0.1 M Bu4NBF4–CH3CN
measured on a Pt electrode (b and c) at the scan rate of 50 mVs−1
.
1
5: H-NMR (l, ppm, C6D6): 1.28 (ꢁC(CH3)3, s, 9H),
4.68 (ꢁC5H5, s, 5H), 6.80ꢁ7.10 (ꢁC6H5, m, 20H). 13C-
NMR (l, ppm, C6D6): 32.10 (ꢁCH3), 53.55 (ꢁNCꢂ),
84.31 (ꢁC5H5), 126.54, 126.99, 127.10, 127.51, 132.41,
135.30 (ꢁC6H5, ꢁC5N). IR (KBr, cm−1): 3054, 2955,
1638, 1599, 1584, 1493, 1443, 1200, 1073, 1028, 756,
702.
5%: 1H-NMR (l, ppm, C6D6+CD3OD): 1.00
(ꢁC(CH3)3, s, 9H), 5.41 (ꢁC5H5, s, 5H), 6.92–7.46
(ꢁC6H5, m, 20H). 13C-NMR (l, ppm, C6D6+CD3OD):
30.09 (ꢁCH3), 54.95 (ꢁNCꢂ), 87.31 (ꢁC5H5), 96.53,
123.82, 127.79, 128.23, 128.55, 128.63, 128.90, 129.49,
130.95. 131.55(ꢁC6H5, ꢁC5N). IR (NaCl, in MeOH
cm−1): 3056, 2961, 1630, 1543, 1481, 1443, 1194, 1076,
1026, 758, 698.
Fig. 6. TGA traces of 1a, 2a, and 3a under nitrogen (10°C min−1).
3.2. Synthesis of (p5-cyclopentadienyl)(p5-N-t-butyl-N-
methylamino-tetraphenylcyclopentadienyl)cobalticinium
iodide (7)
3. Experimental
To a test tube were added 4 (0.148 g, 0.200 mmol),
five equivalents of t-butyl isocyanide (100 ml, 1 mmol),
and benzene (10 ml) under nitrogen and the mixture
was kept stirring at 70°C for 1 day. Iodomethane (1 ml)
was added to the reaction mixture and kept stirring at
room temperature (r.t.) for 1 h. The product was
obtained as a red powder in 98% yield (0.137 g, 1.95
mmol) by precipitation into benzene.
1H- and 13C-NMR spectra were recorded on a JNM-
EX400 spectrometer (400 and 100 MHz, respectively) in
C6D6 and/or CD3OD (tetramethylsilane as internal
standard). IR spectra were obtained on a JASCO FT/
IR-5300 spectrometer. UV–vis spectra were recorded
on a Shimadzu UV-2100 spectrometer in CHCl3. Cyclic
voltammetry experiments were performed with a poten-
tiostat/galvanostat (Hokuto Denko Model HA-301)
and a function generator (Hokuto Denko Model HB-
104) equipped with an X-Y Riken Denshi F-35C
1
7: H-NMR (l, ppm, CD3OD): 1.01 (ꢁC(CH3)3, s,
9H), 2.77 (ꢁCH3, s, 3H), 5.87 (ꢁC5H5, s, 5H), 7.00–7.55
(ꢁC6H5, m, 20H). 13C-NMR (l, ppm, CD3OD): 29.45

I. Tomita et al. / Journal of Organometallic Chemistry 611 (2000) 570–576
575
3b: yield 81% (0.163 g, 0.161 mmol unit): red powder.
1H-NMR (l, ppm, C6D6+CD3OD): 0.80–1.80
(ꢁCH2ꢁ, ꢁCH3, ꢁNC(CH3)3, br, 46H+9H×0.85),
2.60–2.85 (ꢁNCH3, br, 3H×0.65), 3.60–4.00
(ꢁOCH2ꢁ, br, 4H), 4.40–4.50 (ꢁC5H5, br, 5H×0.15),
5.40–5.70 (ꢁC5H5, br, 5H×0.85), 6.50–8.10 (ꢁC6H4ꢁ,
ꢁC6H4Oꢁ, 16H). 13C-NMR (l, ppm, C6D6+CD3OD):
14.67, 23.49, 26.87, 29.60, 30.49, 32.30, 32.80, 44.83,
57.49, 65.61, 68.88, 88.43, 88.56, 89.20, 89.27, 108.14,
115.17, 120.49, 134.09, 154.49, 169.35. IR (KBr, cm−1):
3038, 2924, 2853, 1607, 1572, 1514, 1468, 1391, 1290,
1250, 1177, 1074, 1007, 833, 577.
3c: yield 96% (0.202 g, 0.192 mmol unit). reddish
brown powder. 1H-NMR (l, ppm, C6D6+CD3OD):
0.80–1.70 (ꢁCH2ꢁ, ꢁCH3, ꢁNC(CH3)3, br, 46H+9H×
0.80), 2.65–2.85 (ꢁNCH3, br, 3H×0.55), 4.10–4.60
(ꢁCO2CH2ꢁ, br, 4H+ꢁC5H5, br, 5H×0.20), 5.50–5.80
(ꢁCH3), 42.18 (ꢁCH3), 59.57 (ꢁNCꢂ), 89.61 (ꢁC5H5),
97.35, 99.26, 129.23, 129.27, 129.69, 129.94, 130.11,
130.60, 131.37, 133.09, 133.33 (ꢁC6H5, ꢁC5N). IR
(NaCl, cm−1): 3057, 2930, 1630, 1478, 1445, 1402,
1159, 1074, 1030, 754, 700.
3.3. Synthesis of iminocyclopentadienecobalt-containing
polymer (2a)
To a test tube were added 1a (Mn=6800, Mw/Mn=
1.5, 0.148 g, 0.200 mmol unit), five equivalents of
t-butyl isocyanide (100 ml, 1 mmol), and benzene (10
ml) under nitrogen and the mixture was kept stirring at
70°C for 1 day. To the reaction mixture was added
dried n-hexane (50 ml). The resulting pale brown pow-
dery precipitate was collected by filtration under nitro-
gen, washed with dried n-hexane, and then dried in
vacuo to give 0.099 g (0.180 mmol unit) of 2a.
(ꢁC5H5,
br,
5H×0.80),
6.80–8.40
(ꢁC6H4ꢁ,
ꢁC6H4CO2ꢁ, 16H). 13C-NMR (l, ppm, C6D6+
CD3OD): 15.30, 23.21, 24.13, 26.95, 27.35, 30.02, 30.68,
30.82, 31.10, 31.46, 33.36, 49.09, 66.78, 89.16, 90.19,
101.93, 126.07, 130.99, 132.91, 133.78, 134.28, 149.40,
167.14, 167.45, 179.76, 197.81. IR (KBr, cm−1): 3032,
2926, 2853, 1719, 1607, 1547, 1466, 1391, 1271, 1179,
1107, 1005, 826, 579.
1
2a: H-NMR (d, ppm, C6D6): 1.20–1.50 (ꢁC(CH3)3,
br, 9H×0.85), 4.50–4.60 (ꢁC5H5, br, 5H×0.15), 4.65–
4.85 (ꢁC5H5, br, 5H×0.85), 6.80–8.20 (ꢁC6H4ꢁ,
ꢁC6H5, br, 18H).
1
2a%: H-NMR (l, ppm, C6D6+CD3OD): 0.90–1.30
(ꢁC(CH3)3, br, 9H×0.85), 4.50–4.60 (ꢁC5H5, br, 5H×
0.15), 5.50–5.70 (ꢁC5H5, br, 5H×0.85), 6.90–7.90
(ꢁC6H4ꢁ, ꢁC6H5, br, 18H). 13C-NMR (l, ppm, C6D6+
CD3OD): 30.34, 30.50, 55.67, 88.08, 128.84, 129.13,
129.64, 130.23, 131.02, 132.45, 132.81, 133.01, 133.58,
134.31. IR (KBr, cm−1, under air): 3057, 2969, 1601,
1543, 1501, 1445, 1395, 1370, 1192, 1073, 1005, 758,
700.
References
[1] (a) Y. Wakatsuki, H. Yamazaki, J. Organomet. Chem. 139
(1977) 157. (b) P. Hong, H. Yamazaki, Synthesis (1977) 50. (c)
Y. Wakatsuki, H. Yamazaki, J. Chem. Soc. Dalton Trans.
(1978) 1278. (d) F. W. Grevels, Y. Wakatsuki, H. Yamazaki, J.
Organomet. Chem. 141 (1977) 331. (e) Y. Wakatsuki, H. Ya-
mazaki, J. Organomet. Chem. 149 (1978) 385.
[2] (a) I. Tomita, A. Nishio, T. Igarashi, T. Endo, Polym. Bull. 30
(1993) 179. (b) J.-C. Lee, A. Nishio, I. Tomita, T. Endo,
Macromolecules 30 (1997) 5205.
[3] (a) I. Tomita, A. Nishio, T. Endo, Macromolecules 28 (1995)
3042. (b) J.-C. Lee, I. Tomita, T. Endo, Polym. Bull. 39 (1997)
415. (c) J.-C. Lee, I. Tomita, T. Endo, Macromolecules 31 (1998)
5916.
[4] (a) I. Tomita, A. Nishio, T. Endo, Macromolecules 27 (1994)
7009. (b) I.L. Rozhanskii, I. Tomita, T. Endo, Macromolecules
29 (1996) 1934.
3.4. Synthesis of cobalticinium-containing polymers (3)
(typical procedure for 3a)
To a test tube were added 1a (Mn=9800, Mw/Mn=
1.7, 0.148 g, 0.200 mmol unit), five equivalents of
t-butyl isocyanide (100 ml, 1 mmol), and benzene (10
ml) under nitrogen and the mixture was kept stirring at
70°C for 1 day. To the reaction mixture was added an
excess of iodomethane (1 ml) and stirred overnight at
r.t. The orange powder was precipitated with n-hexane,
washed with benzene and MeOH, and then dried in
vacuo to give 0.114 g (0.176 mmol unit) of 3a. Polymers
3b and 3c were prepared under the similar conditions.
[5] For example, ferrocene-containing oligomers and polymers have
been reported to show interesting electronic properties originat-
ing from the metallic centers. See S. Barlow, D. O’Hare, Chem.
Rev. 97 (1997) 637.
1
[6] (a) H. Yamazaki, Y. Wakatsuki, Bull. Chem. Soc. Jpn. 52 (1979)
1239. (b) K. Yasufuku, A. Hamada, K. Aoki, H. Yamazaki, J.
Am. Chem. Soc. 102 (1980) 4363. (c) J.-C. Lee, I. Tomita, T.
Endo, Chem. Lett. (1998) 121.
3a: H-NMR (l, ppm, C6D6+CD3OD): 0.80–1.30
(ꢁNC(CH3)3, br, 9H×0.85), 2.60–2.80 (ꢁNCH3, br,
3H×0.70), 4.50–4.60 (ꢁC5H5, br, 5H×0.15), 5.50–
5.70 (ꢁC5H5, br, 5H×0.85), 6.90–7.90 (ꢁC6H4ꢁ,
ꢁC6H5, 18H). 13C-NMR (l, ppm, C6D6+CD3OD):
30.58, 42.63, 62.97, 88.30, 89.06, 119.20, 127.41, 128.16,
128.52, 128.82, 129.06, 130.35, 130.81, 131.35, 132.90,
133.56, 135.50. IR (KBr, cm−1): 3054, 2970, 2926,
1603, 1578, 1543, 1501, 1443, 1393, 1188, 1074, 1005,
758, 700.
[7] The 1H-NMR spectrum of 7 in a mixed solvent of C6D6 and
CD3OD revealed a peak for the Cp at 5.87 ppm, much lower
than that of 5 in the same solvent system, probably because 7
does not have any equilibrium as proposed for 5.
[8] The organocobalt polymer 1a containing ca. 85% of the cobalta-
cyclopentadiene moieties was used for this reaction. The remain-
ing 15% was the cyclobutadienecobalt units contaminated during
the synthetic step of 1a. See Ref. [2b].

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I. Tomita et al. / Journal of Organometallic Chemistry 611 (2000) 570–576
[9] Under air, the pale brown-colored polymer 2a turned into pale
[11] The decomposition of 1a originates from the elimination of
triphenylphosphine ligand by the rearrangement to the cyclobu-
tadienecobalt-containing polymer. See Ref. [4].
[12] S.R. Sandler, W. Karo, Organic Functional Group Preparations,
vol. III, second ed., Academic, San Diego, 1989 Chapter 5.
orange less soluble material, probably by oxidation.
[10] As mentioned in the model experiments, attempts to use solvents
with higher polarity for the alkylation failed to result in the
recovery of the starting polymer.
.