Copolymerization of ethylene with methylenecyclopropanes promoted by cobalt and nickel complexes

Article abstract of DOI:10.1246/bcsj.78.1868

The cobalt and nickel complexes promote addition polymerization of substituted methylenecyclopropanes as well as their copolymerization with ethylene to afford the polymers that contain three-membered rings. The homopolymerization of 2-aryl-1-methylenecyclopropane catalyzed by [CoCl ₂(L)]-MMAO (L = bis(1-iminoalkyl)pyridine ligand) at -40°C produces the polymers -(CH₂-CCH₂CHAr)- with a narrow molecular weight distribution. The copolymer of ethylene and 2-aryl-1-methylenecyclopropane is also obtained by using the same catalyst. The ratio of the two monomer units varies in the range from 0 to 0.5 depending on the concentration of ethylene and 2-aryl-1-methylenecyclopropane. ¹³C{¹H} NMR spectrum of the alternating copolymer exhibits a single sharp signal for each carbon of the repeating units. Ethylene and 7-methylenebicyclo[4.1.0]heptane also undergo alternating copolymerization to produce the polymer having the C4 repeating unit containing a bicyclic group. Heating the polymer at 130°C causes ring-opening isomerization to afford the polymer having a C=C double bond in the main chain. Mixtures of [Ni(π-C ₃H₅)Br]₂, a diimine ligand, and cocatalysts such as NaBARF and Et₂AlCl, initiate the copolymerization of ethylene with 2-aryl-1-methylenecyclopropane to give a random copolymer with a low molecular weight (M_n = 1000{2000).

Full text of DOI:10.1246/bcsj.78.1868

1
868 Bull. Chem. Soc. Jpn., 78, 1868–1878 (2005)
Ó 2005 The Chemical Society of Japan
Copolymerization of Ethylene with Methylenecyclopropanes
Promoted by Cobalt and Nickel Complexes
ꢀ
Daisuke Takeuchi, Kouhei Anada, and Kohtaro Osakada
Chemical Resources Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503
Received February 15, 2005; E-mail: kosakada@res.titech.ac.jp
The cobalt and nickel complexes promote addition polymerization of substituted methylenecyclopropanes as well
as their copolymerization with ethylene to afford the polymers that contain three-membered rings. The homopolymer-
ization of 2-aryl-1-methylenecyclopropane catalyzed by [CoCl2(L)]–MMAO (L = bis(1-iminoalkyl)pyridine ligand) at
ꢂ
ꢁ
40 C produces the polymers –(CH2–CCH2CHAr)– with a narrow molecular weight distribution. The copolymer of
ethylene and 2-aryl-1-methylenecyclopropane is also obtained by using the same catalyst. The ratio of the two monomer
units varies in the range from 0 to 0.5 depending on the concentration of ethylene and 2-aryl-1-methylenecyclopropane.
13
1
C{ H} NMR spectrum of the alternating copolymer exhibits a single sharp signal for each carbon of the repeating
units. Ethylene and 7-methylenebicyclo[4.1.0]heptane also undergo alternating copolymerization to produce the polymer
ꢂ
having the C4 repeating unit containing a bicyclic group. Heating the polymer at 130 C causes ring-opening isomer-
ization to afford the polymer having a C=C double bond in the main chain. Mixtures of [Ni(ꢀ-C3H5)Br]2, a diimine
ligand, and cocatalysts such as NaBARF and Et2AlCl, initiate the copolymerization of ethylene with 2-aryl-1-methyl-
enecyclopropane to give a random copolymer with a low molecular weight (Mn ¼ 1000{2000).
Polycycloolefins including polynorbornenes have potential
2-aryl- and 2-ethoxycarbonyl-1-methylenecyclopropanes pro-
moted by Ni complexes to form polymers with three-mem-
uses as optical materials and engineering plastics because
these polymers with regulated structure exhibit optical trans-
parency and a high melting point (Tm) or a glass transition
9
bered rings (Scheme 1). The absence of ring opening during
the polymerization contrasts with the results of the ring-open-
ing polymerization of methylenecyclopropane catalyzed by the
1
temperature (Tg). Copolymers of ethylene and the cycloolefin
10
show lower Tm and Tg than the homopolymers with a cyclic
structure in the monomer units. They could be obtained from
the polymerization of a single monomer only with great diffi-
culty. The thermal properties of the copolymers can be control-
led by changing the ratio of the two monomer units contained
in the polymer chain. Various transition metal complexes
copolymerize ethylene with norbornene in the presence of
Zr and Lu catalyst and of 2-aryl-1-methylenecyclopropanes
1,12
catalyzed by Pd complexes.1
Copolymerization of ethylene
with methylenecyclopropanes without ring-opening would
afford polymers having the three-membered rings in lower
density than the homopolymers of methylenecyclopropanes.
Herein, we report the new living polymerization of 2-phenyl-
1-methylenecyclopropane promoted by Co complexes and the
copolymerization of ethylene with methylenecyclopropanes
promoted by Co and Ni complexes. A part of this study was
presented in a preliminary form.13
2
methylaluminoxane (MAO). The copolymerization catalyzed
by zirconocenes produces the polymers with high optical trans-
parency. A detailed study of the reaction revealed that succes-
sive insertion of norbornene into the metal–polymer bond was
much less favored than alternating insertion of the two mono-
Results and Discussion
2
b
mers. Pd complexes were also reported to catalyze the
copolymerization of ethylene and norbornene to give a copoly-
Addition Polymerization of 2-Aryl-1-methylenecyclopro-
panes by Cobalt Complexes. The cobalt complexes with
bis(1-iminoalkyl)pyridine ligands have been known to catalyze
ethylene polymerization in the presence of modified methyl-
3
mer with a high norbornene content. Alternating copolymer-
ization of ethylene with cyclopentene was catalyzed by the
4
5
vanadium complexes, bis(phenoxyimine)titanium complex,
6
and (indenylamido)titanium complex, to afford the polymers
composed of the C4 repeating units with a five- or six-mem-
bered ring. Random copolymerization of ethylene with norbor-
nene having polar groups was promoted by the Ni complexes.7
Copolymerization of ethylene with other cyclic monomers
is much less common. Marks et al. reported the copolymeriza-
tion of ethylene with 7-methylenebicyclo[4.1.0]heptane, which
accompanied the ring opening of the bicyclic monomer. The
produced polymers have six-membered ring and olefin func-
Lu or Pd
R
R
n
R
n
Ni
R
8
tionality, although the structure of the polymers is not regu-
lated well. Recently, we reported addition polymerization of
Scheme 1. Polymerization of methylenecyclopropanes.
Published on the web October 4, 2005; DOI 10.1246/bcsj.78.1868

D. Takeuchi et al.
Bull. Chem. Soc. Jpn., 78, No. 10 (2005) 1869
R2
R1
N
R1
N
R2
1
R1
R
N
3
R3
R
X
L : R = Pr, R = H, R3 = Me
1
1
i
2
1a: X = H
1b: X = OMe
L : R = H, R = Me, R3 = Me
2
1
2
1
c: X = Cl
L : R = Pr, R = H, R3 = H
3
1
i
2
L : R = H, R2 = Me, R3 = H
4
1
R1
R1
R1
R1
R1
R1
R2
N
N
R2
R2
R2
N
N
R1
R1
L5: R = Pr, R = H
1
i
2
L6: R1 = R2 = Me
7
1
i
2
L : R = Pr, R = H
8
1
2
L : R = H, R = Me
Chart 1.
aluminoxane (MMAO),14,15 although they are not suited for
16
the catalyst of polymerization of propylene and ꢁ-olefins.
1
13
1
ꢂ
Polymerization of 2-aryl-1-methylenecyclopropanes was con-
ducted by using the Co complexes as catalysts. Chart 1 lists the
ligands of the Co complexes employed in this study. 2-Aryl-1-
methylenecyclopropanes, 1a–1c, undergo addition polymer-
Fig. 1. (A) H (rt) and (B) C{ H} NMR (130 C) spectra
ꢂ
of 2a in C D Cl at 130 C. The signals marked by an
2
2
4
asterisk are due to the solvent.
1
1
ization in the presence of [CoCl2(L )] (L = C5H3N{–(Me)C=
PMAO cocatalyst affords the polymer with Mn ¼ 24000
(Mw=Mn ¼ 1:45) in a higher yield (85%) (Run 6) than that
using MMAO as the cocatalyst (55%) (Run 1). Although
Me3Al or Et2AlCl was not effective as the cocatalyst of the
polymerization (Runs 7 and 8), the polymerization using
i
N–C6H3 Pr2-2,6}2-2,6) and MMAO to afford the polymers
containing cyclopropylidene groups, 2a–2c (Eq. 1).
n
CoCl (L ) + MMAO
2
n
i
Bu3Al/NaBARF (NaBARF = NaB{C6H3(CF3)2-3,5}4) initi-
Ar
a: Ar = C H
Ar
ð1Þ
ated the polymerization to produce 2a quantitatively (Run
9). The amount of MMAO can be reduced to ten times molar
amount of Co (Run 13). The reaction with ½Alꢃ=½Coꢃ ¼ 30
results in the highest yield of the polymer among Runs 10–14.
1
1
1
2a: Ar = C H5
6
5
6
b: Ar = C H OMe-4
2b: Ar = C H OMe-4
6
4
6 4
c: Ar = C H Cl-4
2c: Ar = C H Cl-4
6
4
6 4
The 1H and 13C{ H} NMR spectra of 2a contain broad
signals assigned to the hydrogens and carbons of the cyclo-
1
The polymers obtained from the reaction at 0 C and ꢁ40
ꢂ
ꢂ
C have narrow molecular weight distribution (Mw=Mn ¼
1
13
1
propane rings at ꢂ ꢁ0:1–2.4 ( H) and ꢂ 13–47 ( C{ H}), as
shown in Fig. 1. The peak positions are similar to those of
the polymer of 2-phenyl-1-methylenecyclopropane obtained
from Ni complex-promoted polymerization. The absence of
the signals of olefinic carbons and hydrogens indicates no
occurrence of ring opening during the polymerization.
1:15 and 1.16) (Runs 15 and 16). Figure 2A plots the relation-
ship between the conversion of the monomer 1a in the poly-
ꢂ
merization at ꢁ40 C and the molecular weight of the polymer
determined by GPC (gel permeation chromatography). The
molecular weights of 2a are close to those calculated from
the monomer-to-catalyst ratio and increase in proportion to
the conversion of the monomer. A decrease of the Mw=Mn
ratio of the growing polymer from 1.31 to 1.12 is noted during
the reaction. These results indicate the living polymerization
with slower initiation than propagation of the polymer. As
shown in Fig. 2B, the polymer obtained from the reactions
with different initial molar ratios of 1a to Co shows a linear
relationship between Mn and the monomer-to-catalyst ratio.
In each reaction, the produced polymer had a narrow molecular
weight distribution (Mw=Mn ¼ 1:10{1:20). The growing end of
Table 1 summarizes the results of the polymerization. The
reaction of 2-phenyl-1-methylenecyclopropane promoted by
1
[
CoCl2(L )] (½monomerꢃ=½Coꢃ ¼ 200) at room temperature
forms polymer 2a with Mn ¼ 24000 (Mw=Mn ¼ 1:45) (Run
1
). The complex with the ligand without substituents at ortho
2
position of phenyl group (L ) gives the polymer with Mn ¼
1000 (Mw=Mn ¼ 2:04) (Run 2). The bulky ortho substituents
facilitate the formation of narrow molecular weight distribu-
3
3
4
tion. The Co complexes with ligands L and L and a mixture
5
ꢂ
of CoCl2 and diimine ligand, L , show negligible catalytic
the polymer is stable at ꢁ40 C; this stability was examined by
activity for the polymerization (Runs 3–5), which indicates
that the rigid structure of bis(1-iminoalkyl)pyridine ligand is
necessary for smooth polymerization. The reaction using
the polymer growth caused by stepwise addition of the mono-
1
mer. Polymerization of 1a promoted by [CoCl2(L )]/MMAO
ꢂ
with ½1aꢃ=½Coꢃ ¼ 50 at ꢁ40 C causes complete consumption

1
870 Bull. Chem. Soc. Jpn., 78, No. 10 (2005)
Copolymerization of Ethylene with Cycloolefin
aÞ
Table 1. Polymerization of Methylenecyclopropanes by Co Complexes
Temp
bÞ
Time
/min
Yield
/%
Mn
bÞ
Run
Monomer
Co catalyst
cocatalyst
Al/Co
Mw=Mn
ꢂ
ꢁ1
/
C
/g mol
1
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
1a
1a
1a
1a
1a
1a
1a
1a
1a
1a
1a
1a
1a
1a
1a
1a
1b
1c
[CoCl2(L )]
MMAO
MMAO
MMAO
MMAO
MMAO
PMAO
Me3Al
300
300
300
300
300
300
300
300
30
1000
100
30
10
3
rt
rt
rt
rt
rt
rt
rt
rt
rt
rt
rt
rt
rt
rt
15
15
15
15
30
15
30
30
30
15
15
15
15
15
15
15
30
10
55
38
trace
trace
trace
85
trace
trace
quant
46
61
80
24000
31000
—
—
—
24000
—
—
51000
33000
55000
39000
64000
—
1.45
2.04
—
—
—
1.45
—
—
1.59
1.34
1.41
1.39
1.60
—
1.16
1.15
1.54
1.24
2
[CoCl2(L )]
3
[CoCl2(L )]
4
[CoCl2(L )]
5
CoCl2 + L
1
[CoCl2(L )]
1
[CoCl2(L )]
1
[CoCl2(L )]
Et2AlCl
cÞ
1
i
[CoCl2(L )]
Bu3Al
1
1
1
1
1
1
1
1
1
1
[CoCl2(L )]
MMAO
MMAO
MMAO
MMAO
MMAO
MMAO
MMAO
MMAO
MMAO
1
[CoCl2(L )]
1
[CoCl2(L )]
1
[CoCl2(L )]
48
1
[CoCl2(L )]
trace
quant
63
26
80
1
[CoCl2(L )]
300
300
300
300
0
29000
20000
19000
40000
1
[CoCl2(L )]
ꢁ40
ꢁ40
rt
1
[CoCl2(L )]
1
[CoCl2(L )]
ꢁ6
3
a) Reaction conditions: ½Coꢃ ¼ 1:7 ꢄ 10 M, ½monomerꢃ=½Coꢃ ¼ 200, in toluene (5 cm ). b) Determined by GPC
based on polystyrene standard. c) In the presence of NaBARF, ½NaBARFꢃ=½Coꢃ ¼ 1.
of the monomer after 0.5 h and produces the polymer with
Mn ¼ 8300 (Mw=Mn ¼ 1:16). Further addition of the monomer
relative peak area ratios of the signals of 3a indicating the
monomer unit from ethylene and that from 1a are in almost
1
3
1
(
½1aꢃ=½Coꢃ ¼ 100) leads to an increase of the molecular weight
a 1:1 ratio. The C{ H} NMR spectrum of 3a exhibits six
sharp peaks due to the aliphatic carbons in the range: ꢂ
17.2–38.3, as shown in Fig. 3B. The peaks were reasonably
of the growing polymer to Mn ¼ 26000 (Mw=Mn ¼ 1:14).
1
13a
[
CoCl2(L )]/MMAO promotes the polymerization of 2-(4-
methoxyphenyl)-1-methylenecyclopropane (1b) and 2-(4-chloro-
phenyl)-1-methylenecyclopropane (1c), giving the polymers
with cyclopropylidene groups, 2b and 2c, also (Table 1, Runs
assigned to the carbons of the repeating unit of the alternating
1
3
1
copolymer based on the C{ H} and DEPT (Distortionless
Enhancement by Polarization Transfer) spectra as well as on
a comparison of them with that of a model compound (1,1-di-
butyl-2-phenylcyclopropane). The copolymerization of 1b and
1
7 and 18).
Copolymerization of Ethylene with 2-Aryl-1-methylene-
1
3
1
cyclopropanes by Cobalt Complexes. Co complexes with
bis(1-iminoalkyl)pyridine ligand promote the polymerization
of both ethylene and 2-aryl-1-methylenecyclopropanes. The
catalysis is applied to the copolymerization of these mono-
1c with ethylene also proceeds smoothly. The C{ H} NMR
spectra of 3b and 3c exhibit sharp signals, indicating the
alternating copolymerization.
The copolymer of ethylene (1 atm) and 1a (0.17 M in
toluene) contains the monomer units of ethylene and of 1a
in 45:55, while the reaction with ½1aꢃ ¼ 1:23 M produces
the polymer having the monomer units in 26:74 ratio. Thus,
an increase in the initial concentration of 1a changes the ratio
of the two monomer units in the copolymer. Figure 4 shows Tg
of the copolymers. Homopolymer 2a and the alternating
mers. The copolymerization of ethylene (1 atm) with 1a
1
(0.11 g, 0.027 M in toluene) in the presence of [CoCl2(L )]
and MMAO (½1aꢃ=½Coꢃ=½Alꢃ ¼ 200=1=300) at room tempera-
ture for 2 min produces the alternating copolymer of these
monomers 3a (0.046 g), as shown in Eq. 2. GPC traces of 3a
n
CoCl2(L ) + MMAO
ꢂ
ꢂ
n
copolymer exhibit glass transitions at 178 C and at 71 C,
respectively. The Tg value of the copolymers increases with
increase of the monomer unit from 1a. The high Tg of 2a is
ascribed to the rigid polymer chain having the cyclopropyli-
dene group and the aryl substituents.
+
Ar
Ar
ð2Þ
1
1
1
a: Ar = C6H5
3a: Ar = C6H5
b: Ar = C6H4OMe-4
c: Ar = C6H4Cl-4
3b: Ar = C6H4OMe-4
3c: Ar = C6H4Cl-4
detected by RI and by UV (254 nm) show the identical
unimodal elution pattern (Mn ¼ 58000, Mw=Mn ¼ 2:84 (RI)),
suggesting the absence of polyethylene in the product. The
H NMR spectrum of 3a shows the signals of the aliphatic
hydrogens (ꢂ 0.5–1.8) and the aromatic hydrogens (ꢂ 6.9–
Figure 5A shows the relationship between the initial molar
ꢂ
ratio of the two monomers in the polymerization at 0 C and
the ratio of the two monomer units in the copolymer formed
at early stage. The reaction of 1a at a concentration lower than
82 mM ([ethylene]0/([ethylene]0 + [1a]0) > 0.71) produces
the copolymer consisting of the two monomer units with a
ratio close to unity. In contrast, the copolymer prepared from
the reaction with [1a]0 at a concentration higher than 150 mM
([ethylene] /([ethylene] + [1a] ) < 0.57) contains a portion
1
7
that of the homopolymer of 1a. These GPC and H NMR data
.3) (Fig. 3A). The pattern of the signals is quite different from
1
1
3
1
and the C{ H} NMR spectrum mentioned below all indicate
that the product is a copolymer with regulated structure. The
0
0
0

D. Takeuchi et al.
Bull. Chem. Soc. Jpn., 78, No. 10 (2005) 1871
(
A)
40
30
20
10
0
3.0
2.5
2.0
1.5
1.0
0
20
40
60
80
100
Conv./%
(
B)
3
2
1
00
00
00
0
2.0
1
13
Fig. 3. (A) H and (B) C NMR spectra of 3a in C2D2Cl4
ꢂ
at 130 C. The signals marked by an asterisk are due to the
solvent.
1
.5
1
1
1
1
.3
.2
.1
.0
2
1
00
50
2a
alternating
copolymer
0
500 1000 1500 2000
[
1a]/[Co]
Fig. 2. Relationship between molecular weight and (A) con-
version and (B) initial monomer-to-Co molar ratio of the
100
1
polymerization of 1a by [CoCl2(L )]–MMAO. (A) [1a]0/
ꢂ
[
Co]/[Al] = 200/1/300 in toluene (5 mL) at ꢁ40 C.
5
0
0
0.1
0.2
0.3
0.4
0.5
of the monomer unit from 1a larger than that of the ethylene
monomer unit. The copolymerization of 1c with ethylene
showed a similar relationship between the ratio of the initially
charged monomers and the two monomer units in the formed
copolymer. The copolymerization of ethylene with 1b pro-
duces the polymer with lower content of ethylene than the
other two copolymers prepared under the same conditions.
Figure 5B displays linear Fineman–Ross plots of the copoly-
merization. The relative monomer ratios of r1a and rethylene
were calculated to be 0.30 and 0.01, respectively. (r1b,
rethylene) and (r1c, rethylene) were obtained similarly to be (1.1,
molar ratio of CH -CH unit to the total monomer
2
2
units in the copolymer
Fig. 4. Relationship between glass transition temperature
of the produced copolymer and content of the monomer
unit from ethylene in the copolymer.
propanes to transition metal are thermodynamically favored
processes owing to the releases of ring strains of the molecules
caused by the reactions.
Small rethylene values (0.01–0.05) calculated from the
Fineman–Ross plots are consistent with selective insertion of
methylenecyclopropanes into the Co–CH2–CH2– bond. This
is in contrast with the alternating copolymerization of ethylene
with norbornene catalyzed by the Zr and Ti complexes, in
which double insertion of ethylene is much easier than that
of the cyclic monomer (rethylene > 1). Coordination of methyl-
enecyclopropane to transition metal is generally favored due to
the release of the strained energy of the C=C double bond
attached to the three-membered ring.17
0
.05) and (0.18, 0.03), respectively.
Scheme 2 depicts the mechanism proposed for the alternat-
ing copolymerization. The growing polymer with the Co–
CH2–CH2– bond (A) undergoes coordination of methylene-
cyclopropane and 1,2-insertion of its C=C bond into the
Co–C bond to form intermediate B. The C=C bond of 2-
aryl-1-methylenecyclopropane undergoes smooth coordination
to Co of A and subsequent insertion of it into the Co–C bond.
Both the coordination and the insertion of methylenecyclo-

1
872 Bull. Chem. Soc. Jpn., 78, No. 10 (2005)
Copolymerization of Ethylene with Cycloolefin
r1a = 0.30
rethylene = 0.01
(
A)
(B)
1
0
0
0
0
0
.0
4
3
2
1
0
r1b = 1.1
rethylene = 0.05
.8
.6
.4
.2
.0
1
c
1a
r1c = 0.18
rethylene = 0.03
1
b
0.0
0.2
0.4
0.6
0.8
1.0
0
5
10
15
20
F 2/f
[ethylene]0
[
ethylene] +[methylenecyclopropane]
0
0
Fig. 5. (A) Relationship between ethylene content in the monomers and the content of the monomer unit from ethylene in the
copolymer of ethylene with methylenecyclopropanes and (B) Fineman–Ross plots of the copolymerization. F = [methylenecyclo-
propane]0/[ethylene]0 in monomer. f = [methylenecyclopropane]/[ethylene] in polymer.
intermediate C having ꢀ-coordinated methylenecyclopropane
in Scheme 2.
H
Ar
LCo
Polymer
H
The polymerization of 2-aryl-1-methylenecyclopropane
catalyzed by the Co complex/MMAO probably involves 1,2-
insertion of the monomer in order to release steric interaction
between the three-membered ring of the monomer and the
ligands of the catalysts. The growing polymer end, Co–CH2–
CCH2CHAr–, has no ꢃ-hydrogens and does not undergo ꢃ-
hydrogen elimination. Gibson reported that chain transfer of
Ar
(
A)
LCo
Polymer
H
LCo
Polymer
H
H
Ar
Ar
Ar
(C)
1
ethylene polymerization by [CoCl2(L )]/MMAO takes place
by ꢃ-hydrogen elimination rather than by chain transfer of
the growing polymer from Co to Al. Living polymerization
LCo
Ar
Polymer
H
LCo
Polymer
15c
H
H
H
ꢂ
ꢂ
HAr
Ar
of 1a at 0 C and ꢁ40 C is ascribed to the polymer end that
has no ꢃ-hydrogen. Copolymer of 1a and ethylene has a larger
polydispersity (Mw=Mn ¼ 1:35) than that of 2a obtained at 0
Ar
Ar
(B)
H
Ar
ꢂ
Scheme 2. Mechanism of alternating copolymerization of
III
ethylene with methylenecyclopropane. LCo denotes Co
C. The ꢃ-hydrogen of the growing polymer A in Scheme 2
may be responsible to the chain transfer of the copolymer.
The alternating copolymerization, which is initiated by the
living polymer of 1a (½1aꢃ=½Coꢃ ¼ 60, Mn ¼ 12000, Mw=Mn ¼
1:09), affords an AB block copolymer, –(CH2–CCH2CHPh–
CH2–CH2)m–(CH2–CCH2CHPh)n– (Mn ¼ 75000, Mw=Mn ¼
1:76). GPC of the block copolymer showed a single elution
peak, indicating complete consumption of the prepolymer. In
a similar manner, addition of 1b and ethylene to the living
polymer of 1a (½1aꢃ=½Coꢃ ¼ 50, Mn ¼ 9300, Mw=Mn ¼ 1:14)
forms the block copolymer –(CH2–CCH2CH(C6H4OMe-4)-
CH2–CH2)m–(CH2–CCH2CHPh)n– (Mn ¼ 28000, Mw=Mn ¼
bonded to the bis(imino)pyridine ligand.
The intermediate B undergoes insertion of ethylene into the
Co–CH2–CCH2CHAr– bond to regenerate A when the concen-
tration of methylenecyclopropane is low (<82 mM for 1a).
The copolymerization with high concentration of 1a (>82
mM) produces the polymer with higher content of the mono-
mer unit from 1a than that of the ethylene monomer unit.
Figure 5A shows that the copolymer of ethylene with 1b has
a lower content of ethylene monomer unit than that obtained
from copolymerization of ethylene with 1a and 1c, which is
consistent with r1b (1.1) being larger than r1a (0.30) and r1c
1
13
1
1:77) (Eq. 3). H and C{ H} NMR spectra showed the sig-
nals assignable to both –(CH2–CCH2CHPh)– and –(CH2–
CCH2CH(C6H4OMe-4)-CH2–CH2)– segments (Fig. 6).18 GPC
of the obtained copolymers showed a single elution peak. TLC
(silica gel) of the copolymer (eluent: CHCl3) showed a single
spot at Rf ¼ 0:16, which differs from that of 2a (Rf ¼ 1:0)
and 3b (Rf ¼ 0:12). All these results indicate that the obtained
polymer is not a blend of 2a and 3b, but rather the block
copolymer shown in Eq. 3.
(
1
0.18). At present, the reason for different reactivities of 1a–
1
3
1
e toward the copolymerization is not clear. The C{ H}
NMR spectrum of the alternating copolymer (Fig. 3B) shows
a single sharp peak for each carbon of the structural units,
although the signals of the homopolymer (Fig. 1B) are signifi-
cantly broadened. The copolymer has regulated orientation of
the aryl substituents, which is governed by the structure of the

D. Takeuchi et al.
Bull. Chem. Soc. Jpn., 78, No. 10 (2005) 1873
1
MMAO
Al/Co = 300)
CoCl (L ) +
2
(
+
ð4Þ
toluene, -40 °C
n
4
5
The limited solubility of 5 in THF and in CHCl3 prevented
1
3
1
determination of the molecular weight by GPC. The C{ H}
NMR spectrum, however, was obtained by dissolving the poly-
ꢂ
mer in C2D2Cl4 at 130 C, cooling the resulting solution, and
measuring the spectrum at room temperature soon. Seven
sharp signals are assigned to the aliphatic carbons of the alter-
nating copolymer unit, based on comparisons of the peak
positions with those of 7,7-dibutylbicyclo[4.1.0]heptane. The
signals at ꢂ 26.4 and 40.2 are attributed to the CH2 carbons
bonded to the three-membered ring of the polymer. The former
signal is assigned to the carbon on the same side of the cyclo-
hexane-1,2-diyl group, while the latter is due to that on the
opposite side.19
The reaction using C2D4 as the comonomer produces the
deuterated polymer 5-d. The 13C{ H} NMR spectrum of 5-d
shows five sharp signals at ꢂ 19.1, 19.5, 22.7, 25.0, and 26.2,
and two weak signals at ꢂ 22.1 and 39.1 with broadening.
The positions of the latter signals are shifted from the corre-
sponding signals of 5 (ꢂ 23.0 and 40.2) with large isomer shifts
1
(0.921 and 1.012 ppm, respectively). Thus, they are assigned
to the CD2 carbons derived from C2D4 monomer. All these
results indicate that the copolymer of C2D4 and 7-methylene-
bicyclo[4.1.0]heptane, 5-d, has the partial structure shown in
Eq. 5 exclusively.
1
13
1
Fig. 6. (A) H and (B) C{ H} NMR spectra of poly{1a-
ꢂ
block-(1b-alt-ethylene)} in C2D2Cl4 at 130 C. Broad
C NMR signals at ꢂ 0–50 are assigned to w–z. The peaks
by an asterisk are due to the solvent.
13
CoCl2(L1)
MMAO
Al/Co = 300)
+
(
CD2
CD2
+
D2C CD2
CD2
CD2
toluene, -40 °C
n
1
MMAO
Al/Co = 300)
CoCl (L ) +
4
5-d
2
(
ð5Þ
n
toluene, -40 °C
Ph
Ph
Chain growth of the copolymerization is considered to pro-
ceed similarly to that of ethylene with 2-phenyl-1-methylene-
cyclopropane as shown in Scheme 2. The growing polymer
with the Co–CH2–CH2– bond (A in Scheme 2) undergoes 1,2-
insertion of 7-methylenebicyclo[4.1.0]heptane into the Co–C
bond. Pre-coordination of the C=C double bond of the bicyclic
monomer occurs at the opposite side of the six-membered
ring of the monomer in order to avoid any steric repulsion
between the coordinated monomer and the polymer end. The
formed intermediate, having a Co–CH2–C(C6H10)– bond,
undergoes preferential insertion of ethylene into the Co–C
bond. Strong coordination of C=C bond of 4 to the Co center
prevents double insertion of ethylene, similar to the copoly-
merization of ethylene with 1a. Double insertion of 4 is also
inhibited due to the steric bulkiness of the monomer. In fact,
reaction (4) produces the alternating copolymer even at high
concentrations of 4.
ð3Þ
Ar
m
n
toluene, -40 °C
Ar
Ph
(
Ar = Ph, C H OMe-4)
6 4
Copolymerization of 7-Methylenebicyclo[4.1.0]heptane
with Ethylene by Cobalt Complexes. Homopolymerization
of 7-methylenebicyclo[4.1.0]heptane (4) in the presence of
1
ꢂ
[
CoCl2(L )] and MMAO at ꢁ40 C is slow and produces
the polymer in 16% yield after 1 h. The polymer probably has
a structure with three-membered rings similar to those of
2a–2c, although low solubility of the polymer in common
organic solvent prevented detailed NMR analysis of it. The re-
action of ethylene (1 atm) with 4 (0.18 g) in the presence of
1
X X
X X X X
X X
[
CoCl2(L )] and MMAO (½Coꢃ ¼ 1:7 mM, ½Coꢃ=½4ꢃ=½Alꢃ ¼
ꢂ
n
C D Cl , 130 °C
2 2 4
1
in 0.18 g (67% based on 4) after 1 h (Eq. 4). The copolymer-
=200=300) at ꢁ40 C leads to the alternating copolymer 5
XX
X X
n
ð6Þ
ꢂ
5 (X = H)
-d (X = D)
ization for 10 min at ꢁ40 C produces 0.11 g of copolymer
5
and is completed within 1 h. The yield of the copolymer is
ꢂ
6 (X = H)
6
-d (X = D)
low above 0 C.

1
874 Bull. Chem. Soc. Jpn., 78, No. 10 (2005)
Copolymerization of Ethylene with Cycloolefin
ꢂ
Heating a C2D2Cl4 solution of 5 at 130 C for 12 h causes
disappearance of the 13C{ H} NMR signals at ꢂ 19.2–25.2 of
1
5
and generation of new signals of olefinic carbon at ꢂ 123.4
and 144.8 and of a pair of the CH carbons at ꢂ 41.0 and
5.4. The product of the thermal reaction is assigned to 6,
4
(
(
A)
having a structure of poly(2-cyclohexyl-1,3-butadiene), based
on comparison of the spectrum with those of 2-cyclohexyl-2-
2
0
21
butene and poly(isoprene) (Eq. 6). A pair of the signals
for each carbon of the cyclohexyl ring are assigned to the trans
and cis C=C groups in the polymer chain. GPC analysis of 6
shows Mn ¼ 5800 and Mw=Mn ¼ 1:69. 5-d also undergoes the
thermal isomerization to afford the corresponding deuterated
B)
2
polymer 6-d. H NMR spectrum of 6-d show broad signals at
ꢂ 1.15 and 1.93 (CD2) and a much smaller signal at ꢂ 5.05
3
6
Elution Volume/cm-3
(=CD). Organic compounds with similar structures also under-
go the ring-opening isomerization. 2-Methyl-1-phenylcyclo-
propane was reported to undergo photo-isomerization into
Fig. 7. GPC profiles of 7a by (A) UV (254 nm) detector and
(B) RI detector.
2
2
4
-phenyl-1-butene. We conducted thermal reactions of 7,7-
dimethylbicyclo[4.1.0]heptane and 7,7-dibutylbicyclo[4.1.0]-
5
polymerization of 1a by [Ni(ꢀ-C3H5)Br]2–L –NaBARF–
ꢂ
heptane in C2D2Cl4 at 130 C for 12 h, and observed clean
formation of 1-isopropylcyclohexane and (E)-5-cyclohexyl-
Et2AlCl also takes place at room temperature in CH2Cl2 to
give the corresponding polymer with three-membered rings
in 65% yield. Based on the above results, we conducted the
copolymerization of ethylene with 2-aryl-1-methylenecyclo-
propanes using the Ni catalysts. Copolymerization of ethylene
4
-nonene, respectively.23 The first DSC scan of 5 shows an
ꢂ
endothermic peak at 100 C on heating and no exothermic
peak on cooling. The second scan exhibits a transition at 52
ꢂ
C (Tg) only. The results suggest that the ring-opening isomer-
ization of 6 occurs in the solid state also.
(
(
1 atm) and 1a (1.7 M) in the presence of [Ni(ꢀ-C3H5)Br]2
0.0083 mmol), L (0.0083 mmol), NaBARF (0.01 mmol),
8
These isomerization reactions are considered to proceed via
formation of biradical species followed by 1,4-migration of a
hydrogen atom. The thermal isomerization reaction of 5 and
and Et2AlCl (0.83 mmol) produce the copolymer (7a) in 0.31
g (Eq. 7). GPC profiles obtained by UV (254 nm) and RI
detectors (Fig. 7) show similar elution in the high molecular
5
-d also involves homolytic cleavage of C–C bond of the
three-membered ring to form the biradical species, as shown
in Scheme 3. Abstraction of a hydrogen from the CH2 group
by the cyclohexyl radical forms the C=C double bond in the
main chain. Results of the thermal reaction of 5-d indicates
that the hydrogen is abstracted from the CH2 group on the
same side of the cyclohexane-1,2-diyl group with respect to
the cyclopropane plane. 1,4-Migration of a hydrogen of the
CH2 group results in formation of Z and E-olefinic groups in
[
Ni(
π
-allyl)Br] , diimine
2
n
+
NaBARF, Et AlCl
2
Ar
1a: Ar = C H
Ar
6
5
7a: Ar = C H
6
5
1
1
1
b: Ar = C H OMe-4
c: Ar = C H Cl-4
d: Ar = C H Me-4
7b: Ar = C H OMe-4
7c: Ar = C H Cl-4
6 4
7d: Ar = C H Me-4
6
4
6 4
6
4
6
4
6 4
ð7Þ
6
and 6-d.
Polymerization of 2-Aryl-1-methylenecyclopropane and
weight region. A minor elution, observed by RI detector, is
assigned to oligoethylenes (C4–C14) with a molecular weight
of Mn ¼ 1200.
Their Copolymerization with Ethylene Catalyzed by Nickel
Complexes. Addition of NaBARF to a mixture of [Ni(ꢀ-
C3H5)Br]2 and L does not cause ethylene polymerization.
The two mixtures, [Ni(ꢀ-C3H5)Br]2–L –Et2AlCl and [Ni(ꢀ-
C3H5)Br]2–L –NaBARF–Et2AlCl, in contrast, afforded the
1
The H NMR spectrum of 7a shows a broad signal assigned
7
to the phenyl hydrogen at ꢂ 6.3–7.9 and a less broad signal as-
signed to polyethylene segment at ꢂ 0–3.7 (Fig. 8A). Relative
intensity of the signals indicates the content of ethylene segment
to be 90% of the copolymer. These results of the NMR and GPC
measurements indicate that the product is a copolymer of the
two monomers rather than a mixture of the homopolymers.
The broad signals of the methylenecyclopropane unit are in con-
trast to the alternating copolymer obtained by the reaction cata-
lyzed by Co complex and suggest a random sequence of the two
6
7
24
polyethylene in the respective yields of 0.36 and 0.37 g. The
H
H
H
1
13
1
Z-isomer
monomer units. The H and C{ H} NMR spectra of 7a show
the signals due to branched polyethylene segments: (ꢂ 0.8) for
H
H
1
13
1
H, and ꢂ 14.3 and 30.0 for C{ H} (Fig. 8B). Similar branch-
H
ing in high density was reported also for the polyethylene ob-
tained by the Ni catalyst.23 The minor signals at ꢂ 12.3, 17.9,
and 43.0 are assigned to the methylenecyclopropane segment.
E-isomer
13
1
Comparison of the C{ H} NMR spectrum with the DEPT
ꢂ
Scheme 3. Mechanism of thermal isomerization.
spectrum (45 pulse) indicates that the signals at ꢂ 32.4 and

D. Takeuchi et al.
3.7 are due to the cyclopropylidene carbon next to the terminal
Bull. Chem. Soc. Jpn., 78, No. 10 (2005) 1875
i
3
NaBARF and those using Bu3Al or PMAO instead of Et2AlCl
olefinic unit formed by ꢃ-hydrogen elimination.
produce the polymer in low or negligible yields. The reaction
under ethylene at 15 atm affords the polymer with the ethylene
content of 40% (Run 4), while the polymer obtained under
ethylene at 30 atm is insoluble in CHCl3 and THF, due to par-
tial formation of polyethylene (Run 5). Ligands L –L form
the copolymer with different contents of the ethylene unit: 23,
11, and 87%, respectively (Runs 6–8). Chlorobenzene and
toluene were also usable as the solvent for the polymerization
(Runs 9 and 10). The ratio of the two monomer units of the
copolymer varies significantly depending on the ligand used
and the reaction conditions, indicating that the copolymeriza-
tion occurs in random fashion.
Table 2 summarizes the results of the copolymerization. The
reaction under 1 atm of ethylene in the presence of Et2AlCl
cocatalyst gives the polymer in a low yield (Run 1). The poly-
merization with addition of NaBARF affords the polymer
having both monomer units after 2 h (Run 2). Addition of
NaBARF increases both the content of the ethylene unit and
the polymer yield. A longer reaction (15 h) causes partial for-
mation of polyethylene with high molecular weight (Mn ¼
6
8
7
330000). The reactions using AgPF6 or AgBF4 instead of
The copolymerization of ethylene with 1b, 1c, and 1d by
5
[
(
Ni(ꢀ-C3H5)Br]2 (0.0083 mmol)/L (0.0083 mmol)/NaBARF
3
0.01 mmol) in CH2Cl2 (5 cm ) for 15 h gives the copolymers
in lower yields (0.06–0.15 g) than the copolymerization with
a (0.31 g). The content of the ethylene unit in the copolymers
1
was also decreased in the case of these monomers (9–71%). 1a
and 1d gave the copolymer with ethylene in higher yields than
1
polymerization of 2-aryl-1-methylenecyclopropanes.
b and 1c, which is similar to Ni complex-catalyzed homo-
9
b
Conclusion
The Co and Ni complexes promote copolymerization of
ethylene and substituted methylenecyclopropanes, as revealed
by this study. The Co complex with bis(1-iminoalkyl)pyridine
ligand initiates both polymerization of ethylene and that of
methylenecyclopropanes in the presence of MAO as the cocat-
alyst. Preferential coordination of C=C bond of methylene-
cyclopropane to the Co center of the Co–CH2–CH2 growing
end inhibits the double insertion of ethylene during the poly-
merization. This is the primary reason for the selective alter-
nating copolymerization, while double insertion of methylene-
cyclopropane is also restricted under the conditions with high
ethylene/methylenecyclopropane ratios. This copolymeriza-
tion affords the polymer having one three-membered ring in
every four carbons of the main chain. Copolymerization of
ethylene with 2-aryl-1-methylenecyclopropane promoted by
Ni–diimine complexes forms the polymer having three-mem-
bered rings randomly along the polymer chain. Although the
Fig. 8. (A) 1H and (B) C{ H} NMR spectra of 7a in
CDCl3 at 25 C. The signal marked by an asterisk is due
to solvent.
13
1
ꢂ
aÞ
Table 2. Copolymerization of 2-Phenyl-1-methylenecyclopropane with Ethylene by Ni Catalysts
Ni catalysts
Conditions
Products
Ethylene
ꢁ
/% /g mol
Run
bÞ
1
/
a
g
Ethylene
/atm
Time
/h
Yield
/g
MnðMw=MnÞ
1
Ligand
Cocat.
Solvent
5
5
5
5
5
6
7
8
8
8
1
2
3
4
5
6
7
8
9
L
L
L
L
L
L
L
L
L
L
—
0.076
0.11
0.11
0.22
0.22
0.11
0.11
0.11
0.11
0.11
1
1
1
15
30
1
1
1
1
1
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
C6H5Cl
Toluene
15
2
15
3
3
5
0.056
0.068
0.31
0.02
0.09
0.08
0.07
0.31
0.04
0.08
9
1600 (1.50)
—
NaBARF
NaBARF
NaBARF
NaBARF
NaBARF
NaBARF
NaBARF
NaBARF
NaBARF
17
>99
40
insoluble
23
11
1200 (1.4)
1300 (1.6)
2900 (1.6)
1200 (1.6)
1300 (1.8)
1200 (2.61)
1200 (1.36)
1200 (1.40)
2
15
15
15
87
38
71
10
ꢁ6
a) Reaction conditions: [Ni] ¼ 1:7 ꢄ 10 M, [ligand]/[Ni]/[Et2AlCl] = 1/1/100, [Ni]/[NaBARF] = 1:1.2 for Runs 2–
3
9
, solvent 5 cm . b) Determined by GPC based on polystyrene standard.

1
876 Bull. Chem. Soc. Jpn., 78, No. 10 (2005)
Copolymerization of Ethylene with Cycloolefin
3
cocatalysts are different between that used for polymerization
of ethylene and that used for polymerization of 2-aryl-1-meth-
ylenecyclopropane, proper choice of the reaction conditions
has achieved successful random copolymerization of these
monomers. The molecular weight of the copolymer is limited
due to facile ꢃ-hydrogen elimination of the polymer chain
bonded to the Ni center.
g) in a 25-cm Schlenk flask was subjected to a freeze–pump–
thaw cycle, and back-filled with ethylene. A toluene solution of
3
MMAO (0.6 cm , 1.23 mmolAl) was added with a syringe. The
3
mixture was then stirred for 2 min under ethylene flow (1 cm /
min) at room temperature. The reaction mixture was quenched
3
by adding EtOH (ca. 1 cm ) and poured into a large amount of
3
HCl/methanol (ca. 200 cm ). The white precipitates that formed
were collected and dried in vacuo at room temperature. Yield
ꢁ
ꢁ1
ꢁ1
0
2
.12 g. Activity 880 g mmol 1
:84. The molar fraction of ethylene in the polymer was estimated
h
atm . Mn ¼ 58000, Mw=Mn ¼
Experimental
1
General Methods. Anhydrous toluene and deuterated 1,1,2,2-
tetrachloroethane (C2D2Cl4) were used as received. CH2Cl2 was
washed successively with conc. H2SO4, water, and brine, dried
over CaCl2, and distilled over CaH2 under Ar. Ethylene was used
as received. PMAO and MMAO was purchased from TOSOH
FINECHEM and used as received. Co and Ni complexes,14 2-aryl-
by H NMR (C2D2Cl4) based on the peak area ratio of the peaks at
ꢁ0:1–2.4 (CH and CH2 of ethylene unit and 1 unit) and those of
1
6.2–7.5 (Ph of 1 unit). H NMR (C2D2Cl4): ꢂ 0.5–1.8 (9H, m, CH,
CH2) and 7.07 and 7.17 (5H, s, Ph). 13C{ H} NMR (C2D2Cl4):
ꢂ 17.2 (CCH2CHPh), 23.5 (CH2CH2CH2), 27.6 (C), 29.5 (CHPh),
31.3, 38.3 (CCH2), 125.6 (p-Ph), 128.0, 129.1 (o-, m-Ph), and
140.3 (ipso-Ph).
1
1
-methylenecyclopropanes, 2-methyl-2-phenyl-1-methylenecyclo-
propane, and 7-methylenebicyclo[4.1.0]heptane were prepared
according to the reported procedures.25 7,7-Dimethylbicyclo-
Copolymerization of Ethylene with 1b. A toluene solution
3
1
(4.5 cm ) of [CoCl2(L )] (0.0041 mmol, 2.5 mg), 1b (1.66 mmol,
3
[
pared according to the reported procedure.
4.1.0]heptane and 7,7-dibutylbicyclo[4.1.0]heptane were pre-
6
0.27 g) in a 25-cm Schlenk flask was subjected to a freeze–pump–
thaw cycle, and then back-filled with ethylene. A toluene solution
2
NMR spectra ( H and 13C) were recorded on Varian Mercury
1
of MMAO (0.5 cm , 1.23 mmolAl) was added with a syringe, and
3
3
3
00 and JEOL JNM-500 spectrometers, where the chemical shifts
1
the mixture was stirred for 2 min under ethylene flow (1 cm /min)
ꢂ
were determined with respect to C2DHCl2 (ꢂ 5.91) for H and
C2D2Cl4 (ꢂ 74.2) for C. Gel permeation chromatography (GPC)
was performed at 40 C on a TOSOH HLC-8020 high-speed
at 0 C. The reaction mixture was quenched by adding EtOH (ca. 1
3
1
3
cm ). The produced polymer was isolated by pouring the reaction
mixture into a large amount of HCl/methanol. The white pre-
cipitates that formed were collected and dried in vacuo at room
ꢂ
liquid chromatograph system equipped with a differential refrac-
tometer detector and a variable-wavelength UV–vis detector, using
ꢁ
1
ꢁ1
ꢁ1
temperature. Yield 0.22 g. Activity 1600 g mmol
h
atm .
3
ꢁ1
1
THF as an eluent at a flow rate of 0.6 cm min with TSKgel
SuperHM-L and SuperHM-M columns. The molecular weights
were calibrated based on polystyrene standards. DSC and TG
were recorded on Seiko DSC6200R and Seiko TG/DTA6200R
instruments.
Mn ¼ 120000, Mw=Mn ¼ 2:32. H NMR (C2D2Cl4): ꢂ 0.4–1.8
(8H, m, CH, CH2), 3.71 (3H, s, OCH3), and 6.74, 6.76, and 6.97
(4H, s, Ar). 13C{ H} NMR (C2D2Cl4): ꢂ 17.2 (CCH2CHPh), 23.6
(CH2CH2CH2), 27.1 (C), 28.7 (CHPh), 31.4, 38.2 (CCH2), 55.6
1
(OCH3), 114.1, 130.1, 132.5, and 158.2 (Ar).
Copolymerization of Ethylene with 1c by [CoCl2(L )].
1
1
Homopolymerization of 1a by [CoCl2(L )]–MMAO at Room
3
A
toluene solution (1.5 cm ) of [CoCl2(L )] (0.00123 mmol, 0.75
3
1
Temperature. Typically, to a 25-cm Schlenk flask containing a
3
1
3
toluene solution (3.9 cm ) of [CoCl2(L )] (0.0083 mmol, 0.0050
g), 1a (1.75 mmol, 0.228 g), and a magnetic stirring bar under Ar,
mg), 1c (1.23 mmol, 0.2 g) in a 25-cm Schlenk flask was sub-
jected to a freeze–pump–thaw cycle, and then back-filled with
3
3
was added a toluene solution of MMAO (1.1 cm , 2.5 mmolAl)
with a syringe. The mixture was then stirred at room temperature
ethylene. A toluene solution of MMAO (0.6 cm , 1.23 mmolAl)
was added with a syringe, and the mixture was stirred for 2 min
3
ꢂ
3
for 15 min. The reaction mixture was quenched by adding EtOH
3
under ethylene flow (1 cm /min) at 0 C. The reaction mixture
was quenched by adding EtOH (ca. 1 cm ). The produced polymer
(
ca. 1 cm ). The produced polymer was isolated by pouring the
reaction mixture into a large amount of HCl/methanol (ca. 100
was isolated by pouring the reaction mixture into a large amount
of HCl/methanol. The white precipitates that formed were collect-
ed and dried in vacuo at room temperature. Yield 0.11 g. Activity
3
cm ). The white precipitates that formed were collected and dried
1
in vacuo at room temperature. Yield 55%. H NMR (C2D2Cl4):
13
1
ꢁ1 ꢁ1
atm . Mn ¼ 110000, Mw=Mn ¼ 1:81. 1H
ꢁ1
ꢂ ꢁ0:1–2.4 (5H, br, CH, CH2) and 6.2–7.5 (5H, br, Ph). C{ H}
2700 g mmol
h
NMR (C2D2Cl4): ꢂ 13–21 (C, CH2 (cyclopropyl)), 23–31 (CH),
NMR (C2D2Cl4): ꢂ 0.2–2.2 (8H, m, CH, CH2) and 6.96 and
7.15 (4H, s, Ph). 13C{ H} NMR (C2D2Cl4): ꢂ 17.5 (CCH2CHPh),
23.4 (CH2CH2CH2), 27.6 (C), 28.9 (CHPh), 31.3, 38.0 (CCH2),
128.1, 130.4, 131.9, and 140.3 (Ar).
1
3
(
4–47 (CH2), 126.0 (p-Ph), 128.2, 129.1 (o-, m-Ph), and 139.9
ipso-Ph).
1
Homopolymerization of 1a Catalyzed by [CoCl2(L )]–
3
MMAO at À40 ꢀC.
Typically, to a 25-cm Schlenk flask
3
Synthesis
CCH2CHPh)n–.
of
–(CH2–CCH2CHPh–CH2–CH2)m–(CH2–
1
3
1
containing a toluene solution (3.9 cm ) of [CoCl2(L )] (0.0083
mmol, 0.005 g), 1a (1.75 mmol, 0.228 g), and a magnetic stirring
A toluene solution (1 cm ) of [CoCl2(L )]
3
(0.002 mmol, 1.2 mg) and 1a (0.12 mmol, 0.016 g) in a 25-cm
Schlenck flask was subjected to a freeze–pump–thaw cycle, and
then back-filled with ethylene. A toluene solution of MMAO
3
bar under Ar, was added a toluene solution of MMAO (1.1 cm ,
2
.5 mmolAl) with a syringe. The mixture was then stirred at
ꢂ
3
ꢁ
40 C for 15 min. The reaction mixture was quenched by adding
3
(0.25 cm , 0.6 mmolAl) was added with a syringe, and then the
ꢂ
EtOH (ca. 1 cm ). The produced polymer was isolated by pouring
the reaction mixture into a large amount of HCl/methanol (ca. 100
mixture was stirred for 30 min at ꢁ40 C. A part of the reaction
mixture was taken out of the flask and subjected to GPC analysis
(Mn ¼ 12000, Mw=Mn ¼ 1:09). After addition of MMAO (2.5
3
cm ). The formed white precipitates that formed were collected
and dried in vacuo at room temperature. Yield 63%.
3
3
cm , 6 mmol) and 1a (0.11 g, 0.84 mmol), ethylene (1 cm /
ꢂ
Copolymerization of Ethylene with 1a Catalyzed by
1
min) was bubbled at 0 C. After 1 min, the reaction mixture
3
3
[
of [CoCl2(L )] (0.0041 mmol, 2.5 mg) and 1a (0.82 mmol, 0.11
CoCl2(L )]–MMAO. Typically, a toluene solution (29.4 cm )
1
was quenched by adding EtOH (ca. 1 cm ) and then poured into
a large amount of HCl/methanol. The white precipitates that

D. Takeuchi et al.
Bull. Chem. Soc. Jpn., 78, No. 10 (2005) 1877
formed were collected and dried in vacuo at room temperature.
Mn ¼ 75000, Mw=Mn ¼ 1:76.
HCl/methanol formed the polymer as a white precipitate; this
was collected by filtration and dried in vacuo at room temperature.
Yield 0.028 g (16%).
Synthesis of –(CH2–CCH2CH(C6H4OMe-4)-CH2–CH2)m–
3
3
(
uene solution (2 cm ) of [CoCl2(L )] (0.004 mmol, 2.5 mg) was
CH2–CCH2CHPh)n–. A 25-cm Schlenk flask containing a tol-
Thermal Isomerization of 5. A C2D2Cl4 solution (0.5 cm )
3
1
ꢂ
of 5 (0.05 g) was heated at 130 C for 12 h. The solution was sub-
jected to NMR and GPC analyses directly. Mn ¼ 5800, Mw=Mn ¼
subjected to a freeze–pump–thaw cycle, and then back-filled with
3
1
ethylene. A toluene solution of MMAO (0.5 cm , 1.2 mmolAl)
and 2-phenyl-1-methylenecyclopropane (1a) (0.2 mmol, 0.03 g)
1:69. H NMR (C2D2Cl4): ꢂ 1.9–2.2 (m, CH2), 1.12 (br, CH), 1.9–
2.2 (m, CH2), 2.41 (m, CH (cis)), 2.75 (m, CH (trans)), and 5.09
and 5.13 (s, CH=). 13C{ H} NMR (C2D2Cl4): ꢂ 26.7 (CH2 (cyclo-
hexane)), 26.8 (CH2 (cyclohexane)), 27.3 (CH2CH= (cis)), 27.3
(CH2CH= (trans)), 30.9 (=CCH2 (cis)), 31.9 (CH2 (cyclohex-
ane)), 32.1 (CH2 (cyclohexane)), 33.4 (=CCH2 (trans)), 41.0
(CH (trans)), 45.4 (CH (cis)), 123.4 (CH=), and 144.8 (=C).
1
was successively added with a syringe, and the mixture was stirred
ꢂ
for 30 min at ꢁ40 C. A part of the reaction mixture was taken out
of the flask and subjected to GPC analysis (Mn ¼ 9300, Mw=Mn ¼
1
:14). To the reaction mixture was successively added MMAO
3
(2.5 cm , 6 mmol) and 2-(4-methoxyphenyl)-1-methylenecyclo-
propane (1b) (0.13 g, 0.8 mmol) and bubbling with ethylene (1
Preparation of 7,7-Dimethylbicyclo[4.1.0]heptane. To a
3
25-cm Schlenk flask containing CuI (3.36 g, 17.5 mmol), Et2O
3
ꢂ
cm /min) at 0 C. After 2 min the reaction mixture was quenched
3
3
3
by adding EtOH (ca. 1 cm ). The produced polymer was isolated
(70 cm ), and a magnetic stirring bar, was added MeLi (35 cm ,
ꢂ
by pouring the reaction mixture into a large amount of HCl/
methanol. The white precipitates that formed were collected and
dried in vacuo at room temperature. Yield 0.15 g. Mn ¼ 28000,
Mw=Mn ¼ 1:77. TLC (silica gel) of the produced polymer (eluent:
CHCl3) showed single spot at Rf ¼ 0:16, which differs from that
of poly1a (Rf ¼ 1:0) and poly(ethylene-alt-1b) (Rf ¼ 0:12).
Copolymerization of Ethylene with 4. Typically, a toluene
1.0 M solution in ether) with a syringe under Ar at ꢁ45 C.
3
The mixture was stirred for 10 min. An Et2O solution (3.5 cm )
of 7,7-dibromobicyclo[4.1.0]heptane (0.9 g, 3.5 mmol) was added
ꢂ
to the mixture. After stirring for 1 h at ꢁ45 C and for 18 h at 0
ꢂ
3
ꢂ
C, MeI (3.5 cm , 56 mmol) was added to the mixture at 0 C.
This was stirred for 16 h. The resulting mixture was poured into
3
water (ca. 50 cm ). Organic products were extracted with Et2O;
the Et2O layer was then dried with MgSO4. The volatile fraction
was removed by evaporation to afford colorless oil (0.277 g). The
H NMR analysis results indicated the formation of 7,7-dimethyl-
bicyclo[4.1.0]heptane in ca. 80% purity. The compound was
employed for thermal isomerization reaction without further puri-
3
1
solution (3.7 cm ) of [CoCl2(L )] (0.0083 mmol, 5 mg) and
7
2
-methylenebicyclo[4.1.0]heptane (4) (1.66 mmol, 0.18 g) in a
3
1
5-cm Schlenk flask, was subjected to a freeze–pump–thaw
cycle, and then back-filled with ethylene. A toluene solution of
3
MMAO (1.3 cm , 2.5 mmolAl) was added with a syringe; the
3
1
mixture was then stirred for 1 h under ethylene flow (1 cm /
ꢂ
fication. H NMR (C2D2Cl4): ꢂ 0.45 (2H, d, J ¼ 7:5 Hz, CH),
min) at ꢁ40 C. The reaction mixture was quenched by adding
0.87 (3H, s, CH3), 0.89 (3H, s, CH3), 1.09 (4H, m, CH2), 1.28
(2H, m, CH2), and 1.74 (2H, m, CH2). 13C{ H} NMR (C2D2Cl4):
ꢂ 15.7 (CH3), 17.4 (C), 19.2 (CH), 19.5 (CH2 (cyclohexane)), 21.5
(CH2 (cyclohexane)), and 29.8 (CH3).
3
1
EtOH (ca. 1 cm ). The produced polymer was isolated by pouring
the reaction mixture into a large amount of HCl/methanol. The
white precipitate thus formed was collected by filtration and dried
1
in vacuo at room temperature. Yield 0.18 g. H NMR (C2D2Cl4):
Thermal Isomerization of 7,7-Dimethylbicyclo[4.1.0]heptane.
3
ꢂ 0.46 (2H, s, CH), 1.15 (8H, br, CH2), 1.26 (4H, br, CH2), and
A C2D2Cl4 solution (0.5 cm ) of 7,7-dimethylbicyclo[4.1.0]-
1
3
1
ꢂ
1
.74 (2H, s, CH (cyclohexane)). C{ H} NMR (C2D2Cl4): ꢂ 19.2
heptane (0.05 g) was heated at 130 C for 12 h. The solution
(
(
CH), 19.5 (CH2 (cyclohexane)), 22.7 (CH2 (cyclohexane)), 23.0
CH2), 25.2 (C), 26.4 (CH2), and 40.2 (CH2).
was subjected to NMR analysis without isolation of the product.
The main product was assigned by comparison of the NMR data
with those of isopropylcyclohexane.23 H NMR (C2D2Cl4): ꢂ 0.91
(6H, d, J ¼ 7 Hz, CH3), 1.47 (2H, m, CH2), 1.54 (2H, m, CH2),
1.86 (2H, s, CH2), 1.92 (2H, s, CH2), 2.07 (1H, septet, J ¼ 7
Hz, CH), and 5.31 (1H, s, =CH). 13C{ H} NMR (C2D2Cl4): ꢂ
21.7 (CH3), 23.2 (CH2 (cyclohexane)), 23.5 (CH2 (cyclohexane)),
25.6 (CH2 (cyclohexane)), 26.3 (CH2 (cyclohexane)), 35.5 (CH),
118.5 (=CH), and 143.8 (C=).
1
Copolymerization of C2D4 with 4. Typically, a toluene solu-
3
1
tion (3.7 cm ) of [CoCl2(L )] (0.0083 mmol, 5 mg) and 7-methyl-
enebicyclo[4.1.0]heptane (4) (1.66 mmol, 0.18 g) in a 25-cm3
Schlenk flask, was subjected to a freeze–pump–thaw cycle, and
then back-filled with C2D4. A toluene solution of MMAO (1.3
1
3
cm , 2.5 mmolAl) was added with a syringe, and the mixture
ꢂ
was stirred for 1 h under C2D4 atmosphere (1 atm) at ꢁ40 C.
3
The reaction mixture was quenched by adding EtOH (ca. 1 cm ).
Preparation of 7,7-Dibutylbicyclo[4.1.0]heptane. To a 25-
cm3 Schlenk flask containing CuI (3.36 g, 17.5 mmol), Et2O
The produced polymer was isolated by pouring the reaction mix-
ture into a large amount of HCl/methanol. The white precipitate
thus formed was collected by filtration and dried in vacuo at room
temperature. Yield 0.18 g. 1H NMR (C2D2Cl4): ꢂ 0.51 (2H, s,
CH), 1.18 (6H, br, CH2), 1.30 (2H, br, CH2), and 1.79 (2H, s,
CH (cyclohexane)). C{ H} NMR (C2D2Cl4): ꢂ 19.1 (CH), 19.5
(
(
3
ꢂ
(70 cm ), and a magnetic stirring bar under Ar at ꢁ45 C, were
3
successively added n-BuLi (22 cm , 1.6 M solution in hexane)
3
and Et2O solution (3.5 cm ) of 7,7-dibromobicyclo[4.1.0]heptane
(0.9 g, 3.5 mmol) with a syringe. The mixture was stirred at ꢁ45
13
1
ꢂ
ꢂ
3
C for 1 h and at 0 C for 18 h. n-BuI (6.4 cm , 56 mmol) was
ꢂ
CH2 (cyclohexane)), 22.1 (CD2), 22.7 (CH2 (cyclohexane)), 25.0
added to the mixture at 0 C; this mixture was stirred for 16 h.
The mixture was then poured into water, extracted with Et2O,
and dried with MgSO4. The volatile fraction was evaporated to
afford colorless oil (0.7 g, ca. 70% purity by NMR). It was used
for the thermal isomerization reaction without further purification.
C), 26.2 (CH2), and 39.1 (CD2).
ꢀ
3
Homopolymerization of 4 at À40 C. Typically, to a 25-cm
3
Schlenk flask containing
1
a
toluene solution (3.7 cm ) of
CoCl2(L )] (0.0083 mmol, 5 mg), 7-methylenebicyclo[4.1.0]-
[
heptane (4) (1.66 mmol, 0.18 g), and a magnetic stirring bar under
1
H NMR (C2D2Cl4): ꢂ 0.45 (2H, s, CH), 0.81 (3H, s, CH3), 0.85
3
Ar, was added a toluene solution of MMAO (1.3 cm , 2.5
ꢂ
(3H, s, CH3), 1.1–1.4 (18H, m, CH2), and 1.74 (2H, s, CH2).
13
1
mmolAl) with a syringe. The mixture was then stirred at ꢁ40 C
C{ H} NMR (C2D2Cl4): ꢂ 14.7 (CH3), 19.1 (CH), 19.5 (CH2
for 30 min. The reaction mixture was quenched by adding EtOH
3
(cyclohexane)), 22.7 (CH2 (cyclohexane)), 23.8 (CH3CH2), 25.2
(C), 25.9 (CH2C), 28.7 (CH2), 28.8 (CH2), and 39.3 (CH2C).
(
ca. 1 cm ). Pouring the reaction mixture into a large amount of

1
878 Bull. Chem. Soc. Jpn., 78, No. 10 (2005)
Copolymerization of Ethylene with Cycloolefin
Thermal Isomerization of 7,7-Dibutylbicyclo[4.1.0]heptane.
3
460 (2000). b) G. M. Benedikt, E. Elce, B. L. Goodall, H. A.
Kalamarides, L. H. McIntosh, III, L. F. Rhodes, K. T. Selvy, C.
Andes, K. Oyler, and A. Sen, Macromolecules, 35, 8978 (2002).
A C2D2Cl4 solution (0.5 cm ) of 7,7-dimethylbicyclo[4.1.0]-
ꢂ
heptane (0.1 g) was heated at 130 C for 12 h. The solution was
subjected to NMR analysis without isolation of the product. The
main product was assigned to be (E)-5-cyclohexyl-4-nonene by
comparison of the NMR results with the reported data of (E)-
and (Z)-2-cyclohexyl-2-butene.20b H NMR (C2D2Cl4): ꢂ 0.81
8
(2003). b) T. R. Jensen, J. J. O’Donnell, III, and T. J. Marks,
a) T. R. Jensen and T. J. Marks, Macromolecules, 36, 1775
Organometallics, 23, 740 (2004).
9
1
a) D. Takeuchi and K. Osakada, Chem. Commun., 2002,
646. b) D. Takeuchi, K. Anada, and K. Osakada, Macromolecules,
35, 9628 (2002).
(
6H, t, J ¼ 7 Hz, CH3), 1.10 (2H, m, CH2 (cyclohexane)), 1.20
(
10H, m, CH2), 1.50 (2H, m, CH2 (cyclohexane)), 1.73 (4H, m,
=
C–CH2), 1.92 (3H, m, CH, CH2–CH=), and 5.28 (1H, s,
10 a) X. Yang, L. Jia, and T. J. Marks, J. Am. Chem. Soc., 115,
3392 (1993). b) L. Jia, X. Yang, A. M. Seyam, I. D. L. Albert, P.-F.
Fu, S. Yang, and T. J. Marks, J. Am. Chem. Soc., 118, 7900 (1996).
11 a) D. Takeuchi, S. Kim, and K. Osakada, Angew. Chem.,
Int. Ed., 40, 2685 (2001). b) S. Kim, D. Takeuchi, and K.
Osakada, ‘‘Perspectives in Organometallic Chemistry,’’ ed by
C. G. Screttas and B. R. Steele, The Royal Chemical Society,
Cambridge (2003), pp. 306–316.
12 For review on polymerization and copolymerization of
methylenecyclopropanes: K. Osakada and D. Takeuchi, Adv.
Polym. Sci., 170, 137 (2004).
13 a) D. Takeuchi, K. Anada, and K. Osakada, Angew. Chem.,
Int. Ed., 43, 1233 (2004). b) D. Takeuchi and K. Osakada,
Macromolecules, 38, 1528 (2005).
14 E. Y.-X. Chen and T. J. Marks, Chem. Rev., 100, 1391 (2000).
15 a) B. L. Small, M. Brookhart, and A. M. A. Bennett, J. Am.
Chem. Soc., 120, 4049 (1998). b) G. J. P. Britovsek, V. C. Gibson,
B. S. Kimberley, P. J. Maddox, S. J. McTavish, G. A. Solan,
A. J. P. White, and D. J. Williams, Chem. Commun., 1998, 849.
c) G. J. P. Britovsek, M. Bruce, V. C. Gibson, B. S. Kimberley,
P. J. Maddox, S. Mastroianni, S. J. McTavish, C. Redshaw,
G. A. Solan, S. Str o¨ mberg, A. J. P. White, and D. J. Williams,
J. Am. Chem. Soc., 121, 8728 (1999). d) T. M. Kooistra, Q.
Knijnenburg, J. M. M. Smits, A. D. Horton, P. H. M. Budzelaar,
and A. W. Gal, Angew. Chem., Int. Ed., 40, 4719 (2001).
CH=). 13C{ H} NMR (C2D2Cl4): ꢂ 14.5 (CH3), 23.2 (CH3CH2),
3.4 (CH2), 23.5 (CH2), 24.3 (CH2CH=), 25.7 (CH2 (cyclohex-
ane)), 30.2 (=CCH2), 33.6 (CH2 (cyclohexane)), 47.9 (CH), 122.1
1
2
(
CH=), and 140.0 (=C).
Copolymerization of Ethylene with 1a Catalyzed by Ni
3
Catalyst. To a 25-cm Schlenk flask containing a CH2Cl2 solu-
tion (5 cm ) of [Ni(ꢀ-C3H5)Br]2 (0.0083 mmolNi, 0.0015 g), di-
imine ligand (L , 0.0083 mmol, 0.003 g), and NaBARF (0.01
mmol, 0.0089 g) was added 1a (0.11 g, 0.83 mmol) with a syringe
at room temperature. The mixture was frozen with liq. N2, evac-
uated, backfilled with ethylene, and warm to room temperature. A
hexane solution of Et2AlCl (1 mol/L, 0.83 mL) was added to the
mixture, which was stirred for 15 h at room temperature; the reac-
tion mixture was then quenched by adding HCl/MeOH. The pro-
duced polymer was isolated by pouring a chloroform solution of
3
8
the polymer into a large amount of methanol as brown oil.
1
7a:
H NMR (CDCl3): ꢂ ꢁ0:3–4.2 (br, CH, CH2, CH3) and
13 1
6
.3–7.8 (br, C6H5). C{ H} NMR (CDCl3): ꢂ 12.7, 14.1 (CH3
(
terminal)), 17.9, 19.7 (CH2), 22.7 (CH2 (terminal)), 26.7 (CH2),
27.1 (CH2), 28.9–30.2 (CH2), 31.9 (CH2 (terminal)), 32.6 (CH),
33.7 (CH2), 33.8 (CH2), 37.1 (CH), 43.0, 124–130 (Ph), and
139.3 (ipso-Ph).
This work was supported by a Grant-in-Aid for Young Sci-
1
1
6
7
B. L. Small, Organometallics, 22, 3178 (2003).
a) K. Osakada, H. Takimoto, and T. Yamamoto, Organo-
entist (No. 16750091) for Scientific Research from the Minis-
try of Education, Culture, Sports, Science and Technology,
Japan.
metallics, 17, 4532 (1998). b) K. Osakada, H. Takimoto, and
T. Yamamoto, J. Chem. Soc., Dalton Trans., 1999, 853.
13
1
8
C NMR peak at 30 ppm in Fig. 6 is assigned to the poly-
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