Controlled vinyl-addition-type polymerization of norbornene initiated by several cobalt complexes having substituted terpyridine ligands

Article abstract of DOI:10.1016/j.jorganchem.2003.11.024

A series of cobalt(II) complexes having terpyridine derivatives such as 2,2′:6′,2″-terpyridine (1), 4,4′, 4″-^t Bu₃ -2,2′:6′, 2″-terpyridine (2), 5,5″-Me₂-2,2′:6′, 2″-terpyridine (3), 6,6″-Me₂-2, 2′:6′,2″-terpyridine (4) and 6,6″-(3,5-Me₂C₆H₃)₂ -2,2′:6′,2″-terpyridine (5) was synthesized. The structures of 1, 3, and 4 were confirmed by X-ray crystallography. The coordination sphere around the cobalt center in 1 can be described as pseudo square pyramidal. On the other hand, complex 4 has pseudo trigonal bipyramidal structure. Upon activation with d-MAO (dried-methylaluminoxane), these complexes showed high activities for the polymerization of norbornene (NBE). In particular, polymerization of NBE with 4/d-MAO system at room temperature resulted in quantitative yield within several hours to give the polymers with relatively narrow molecular weight distributions and controlled molecular weight. The polymerizations of NBE with these cobalt catalyst systems proceeded in vinyl addition polymerization, which was confirmed by ¹H NMR spectra of the resulting polymers.

Full text of DOI:10.1016/j.jorganchem.2003.11.024

Journal of Organometallic Chemistry 689 (2004) 744–750
www.elsevier.com/locate/jorganchem
Controlled vinyl-addition-type polymerization of
norbornene initiated by several cobalt complexes
having substituted terpyridine ligands
*
Yoshinori Sato, Yuushou Nakayama, Hajime Yasuda
Department of Applied Chemistry, Graduate School of Engineering, Hiroshima University, Higashi-Hiroshima 739-8527, Japan
Received 3 June 2003; accepted 27 November 2003
Abstract
A series of cobalt(II) complexes having terpyridine derivatives such as 2,20 :60 ,200-terpyridine (1), 4,40 ,400-tBu3-2,20 :60 ,200-terpyridine
(2), 5,500-Me2-2,20 :60 ,200-terpyridine (3), 6,600-Me2-2,20 :60 ,200-terpyridine (4) and 6,600-(3,5-Me2C6H3)2-2,20 :60 ,200-terpyridine (5) was
synthesized. The structures of 1, 3, and 4 were confirmed by X-ray crystallography. The coordination sphere around the cobalt
center in 1 can be described as pseudo square pyramidal. On the other hand, complex 4 has pseudo trigonal bipyramidal structure.
Upon activation with d-MAO (dried-methylaluminoxane), these complexes showed high activities for the polymerization of nor-
bornene (NBE). In particular, polymerization of NBE with 4/d-MAO system at room temperature resulted in quantitative yield
within several hours to give the polymers with relatively narrow molecular weight distributions and controlled molecular weight.
The polymerizations of NBE with these cobalt catalyst systems proceeded in vinyl addition polymerization, which was confirmed by
1H NMR spectra of the resulting polymers.
Ó 2003 Elsevier B.V. All rights reserved.
Keywords: Cobalt; Terpyridine; Norbornene; Polymerization
1. Introduction
similar coordination geometry to bis(imino)pyridine and
their extended conjugation system. Our preliminary
studies on the polymerization of ethylene by terpyridine
complexes of several late transition metals revealed that
their activities for the ethylene polymerization were ra-
ther low. In the course of this study, we found that ter-
pyridine cobalt complexes were very effective for the
vinyl-type polymerization of norbornene (NBE).
Great interest lies in its polymerization mecha-
nism including ring-opening metathesis polymerization
(ROMP), vinyl addition polymerization, and radical
polymerization, which are controlled by metal of cata-
lyst center or cocatalyst (Scheme 1). Polymers obtained
by ROMP and vinyl addition are useful as high oil-
absorbing materials, shape-memory resin, and optical
materials. In the case of polymerization of NBE with
cobalt carboxylate complex, ROMP proceeds upon ac-
tivation with alkylaluminum compounds, while vinyl
addition polymerization proceeds in combination with
MAO [5]. In the field of vinyl-type polymerization of
NBE, living polymerization has not yet been achieved,
Group 4 transition metal complexes have been ex-
tensively studied as precursors of the homogeneous cat-
alysts for olefin polymerization [1,2]. On the other hand,
several new late transition metal-based non-metallocene
complexes have recently emerged as potentially useful
single site catalysts for olefin polymerization. A signifi-
cant development in late transition metal polymerization
catalyst technology was reported by Brookhart and co-
workers who showed that the catalysts based on nickel
and palladium could be used to access a range of linear
and branched polyethylenes [3]. Iron(II) and cobalt(II)
complexes with tridentate bis(imino)pyridine ligands
also have a potential for producing a much broader
range of polyolefinic materials at low cost [4]. We have
been interested in terpyridine type ligands due to their
* Corresponding author. Tel.: +81-824-24-7730; fax: +81-824-24-
5494.
E-mail address: yasuda@hiroshima-u.ac.jp (H. Yasuda).
0022-328X/$ - see front matter Ó 2003 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2003.11.024

Y. Sato et al. / Journal of Organometallic Chemistry 689 (2004) 744–750
745
ROMP
Ti, Ta, Mo, W, Re, Ru, Os, Co
n
vinyl-type polymerization
Ti, Zr, Cr, Co, Ni, Pd
n
n
cation or radical polymerization
n
Fig. 1. Molecular structure of 1. Thermal ellipsoids are the 50%
probability level.
Scheme 1.
Table 1
while living ring-opening metathesis polymerization has
already been widely known [6].
ꢀ
Selected bond lengths (A) and angles (°)
Complex 1
Complex 3
Complex 4
In this study, we synthesized a series of cobalt(II)
complexes having terpyridine derivatives, and examined
catalytic activity for the polymerization of NBE to give
the polymers with controlled molecular weight and rel-
atively narrow molecular weight distributions.
Bond lengths
Co–N(1)
Co–N(2)
Co–N(3)
Co–Cl(1)
Co–Cl(2)
2.143(2)
2.069(2)
2.159(2)
2.3171(8)
2.2815(8)
2.164(2)
2.070(2)
2.156(2)
2.2895(9)
2.2808(9)
2.207(2)
2.029(2)
2.2192(2)
2.2960(9)
2.2921(8)
Bond angles
2. Results and discussion
Cl(1)–Co–Cl(2)
Cl(1)–Co–N(1)
Cl(1)–Co–N(2)
Cl(1)–Co–N(3)
Cl(2)–Co–N(1)
Cl(2)–Co–N(2)
Cl(2)–Co–N(3)
N(1)–Co–N(2)
N(1)–Co–N(3)
N(2)–Co–N(3)
110.42(3)
96.12(7)
98.87(7)
101.76(7)
101.31(7)
150.70(7)
97.15(7)
75.77(9)
147.90(9)
75.29(9)
115.13(4)
97.33(7)
100.12(7)
101.53(7)
96.59(7)
144.61(7)
98.81(7)
75.03(9)
147.65(9)
75.94(9)
125.48(3)
96.54(7)
111.82(7)
95.85(7)
96.27(7)
122.70(7)
95.29(7)
76.81(9)
153.65(9)
77.01(9)
2.1. Syntheses and structures of cobalt(II) complexes
A series of cobalt(II) complexes 1–5 having terpyri-
dine (Tpy) derivatives as tridentate N-donor ligands was
synthesized by the reaction of CoCl2 with a stoichiom-
etric amount of terpyridines at room temperature in
good yield (Scheme 2).
Harris et al. reported the crystal properties of
CoCl2(terpyridine) 1. However only the space group and
cell parameters were described in their paper [7]. Thus,
we performed the X-ray crystallography of 1 to compare
with other new substituted terpyridine complexes. Fig. 1
shows the molecular structure of 1. The selected bond
distances and angles are summarized in Table 1. The
Complex 1 has mononuclear pseudo square pyramidal
geometry, in which Cl(1) occupies an apical position.
The Cl(1)–Co–N(2) and Cl(2)–Co–N(2) angles are
98.87(7)° and 150.70(7)°, respectively. The Co–N(1) and
ꢀ
Co–N(3) bond lengths [2.143(2) and 2.159(2) A] are
ꢀ
longer than Co–N(2) [2.069(2) A].
In order to elucidate the effects of the substituents, we
systematically synthesized a series of new cobalt com-
plexes having various substituted terpyridine ligands.
A cobalt complex having a commercially available
4,40 ,400-tri-tert-butyl-2,20 :60 ,200-terpyridine, CoCl2(4,40 ,400-
tri-tert-butyl-2,20 :60 ,200-terpyridine) 2, was obtained as a
gray powder in 80%0 yi0eld.
R3
R3
N
R3
N
R3
N
R3
R2
R3
R2
R2
R1
R2
R1
N
CoCl2
THF
N
N
Co
R1
R1
Cl
Cl
Complex
R1
R2
R3
H
5,500-Dimethyl-2,2 :6 ,200-terpyridine (5,500-Me2Tpy)
was prepared according to the literature [8], in which
6,600-dimethyl-2,20 :60 ,200-terpyridine (6,600-Me2Tpy) could
not be synthesized in the same manner to that for 5,500-
Me2Tpy, but obtained from the reaction of 2,6-
bis(trimethytin)pyridine and 2-bromo-6-methylpyridine
in 43% yield. Here, we succeeded in the preparation of
1
2
3
4
5
H
H
H
H
H
t-Bu
H
Me
H
Me
3,5-Me2C6H3
H
H
H
Scheme 2.

746
Y. Sato et al. / Journal of Organometallic Chemistry 689 (2004) 744–750
the 6,600-Me2Tpy as a Stille-type coupling [9] of 2-trib-
utyltin-6-methylpyridine and 2,6-dibromopyridine in
80% yield (Scheme 3).
ence between the two of N(2)–Co–Cl angles are 44.49° in
3 and 51.83° in 1, while only 10.88° in 4. The coordi-
nation sphere around the metal in 4 is restricted to have
pseudo trigonal bipyramidal structure due to the steric
hindrance of 6- and 600-methyl groups on the terpyridine
ligand. The methyl substitutions at 5- and 500-positions
in 3 also affect the coordination geometry, although the
effect is weaker than those at 6- and 600-positions in 4.
The tendencies of Co–N bonds distances of 3 and 4 are
similar to 1: Co–N(2) bond lengths are shorter than Co–
N(1) and Co–N(3) lengths.
We have recently developed terpyridine derivatives
having bulky substituents at 6- and 600-positions0[10]. In
this study, CoCl2[6,600-(3,5-Me2C6H3)2-2,20 :6 ,200-ter-
pyridine] 5 was synthesized. Complex 5 was character-
ized by elemental analysis.
Cobalt complexes having dimethylterpyridine li-
gands, CoCl2(5,500-Me2Tpy) 3 and CoCl2(6,600-Me2Tpy)
4, were obtained as a green powder in 99% and 82%
yield, respectively. Single crystals of 3 and 4 suitable for
X-ray diffraction studies were obtained by recrystalli-
zations from CH2Cl2/hexane. The molecular structures
of these complexes are shown in Figs. 2 and 3. The se-
lected bond distances and angles are included in Table 1.
In sharp contrast to the pseudo square pyramidal ge-
ometry of 1, the geometry of 4 can be described as
pseudo trigonal bipyramidal in which N(1) and N(3) are
located at apical positions. The complex 3 has an in-
termediate geometry between square pyramidal and
trigonal bipyramidal. The Cl(1)–Co–N(2) and Cl(2)–
Co–N(2) angles are 100.12(7)° and 144.61(7)° in 3,
111.82(7)° and 122.70(7)° in 4, respectively. The differ-
A cobalt(II) complex bearing 2,6-bis(imino)pyridine
type tridentate N-donor ligand, CoCl2{2,6-bis[1-(2,6-
diisopropylphenylimimno)ethyl]pyridine} 6, was pre-
pared according to the literature [11] for comparison of
catalytic properties with those of terpyridine complexes.
Pd(PPh3)4
80 %
N
N
2
+
2.2. Polymerizations of norbornene
N
N
Br
N
Sn(n-Bu)3
Br
The catalyses of these cobalt complexes 1–6 for the
polymerization of NBE were investigated in the presence
of aluminum cocatalyst. Without cocatalyst, these
complexes showed no catalytic activity. The complexes
1–5 showed very low activities (ꢀ5% yield) for poly-
merization of NBE upon activation with MMAO. Thus,
we used d-MAO as a cocatalyst for these cobalt com-
plexes. d-MAO was prepared by drying ordinary MAO
(toluene solution) in vacuo at 40 °C to remove toluene
and AlMe3 and used as a solution in chlorobenzene.
Table 2 summarized the polymerization of NBE by
the cobalt complexes 1–5 activated with d-MAO. In
combination with d-MAO, catalytic activities of these
complexes were drastically increased compared to the
MMAO systems and the polymerization of NBE with
these cobalt catalyst systems proceeded in vinyl addition
polymerization, which was confirmed by 1H NMR
spectra of the resulting polymers (Fig. 4). In particular,
polymerization of NBE with 4/d-MAO system at room
temperature resulted in quantitative yield within 3 h
while other systems required more than 12 h to achieve
complete consumption of the monomer. On the other
hand, the molecular weight distributions (MWD) of
poly(NBE) obtained by 1 or 2 were found to be rela-
tively narrow (Mw=Mn ꢀ 1:2). With increasing the steric
hindrance around cobalt center, the polymer yield
decreased. The complex 5 having large substituents at 6-
and 600-positions of terpyridine, showed the lowest ac-
tivity among these terpyridine systems. Similarly, the
2,6-diisopropylphenyl groups of bis(imino)pyridine li-
gand in 6, which were necessary for inhibition of b-H
elimination to proceed high polymerization of ethylene,
Scheme 3.
Fig. 2. Molecular structure of 3. Thermal ellipsoids are the 50%
probability level.
Fig. 3. Molecular structure of 4. Thermal ellipsoids are the 50%
probability level.

Y. Sato et al. / Journal of Organometallic Chemistry 689 (2004) 744–750
747
Table 2
Polymerization of Norbornene with cobalt complexes/d-MAO systems
Mn ꢁ 10ꢂ4a
4.1
6.0
Mw=Mn
a
Complex
Time (h)
Yield (%)
1
3
12
62
>99
1.66
1.22
2
3
4
5
3
12
30
>99
3.2
6.4
1.87
1.21
Fig. 5. Space filling models of 1, 3, and 4. Calculated by Crystal-
Structure 3.10.
3
12
60
94
5.1
7.9
1.38
1.33
3
12
>99
>99
3.2
4.5
1.61
1.36
polymer chain could be situated at two equivalent
equatorial positions. As a consequence, 4/d-MAO sys-
tem becomes active than 3/d-MAO in which one pseudo
axial position would be located close to crowded ter-
pyridine plane. In the case of 1/d-MAO and 2/d-MAO
systems, d-MAO anions could more strongly tie to the
cobalt cation so that the growing rate of poly(NBE)
might be slowed down and a chain transfer reaction
should be hindered to give polymers with relatively
narrow MWD.
Table 3 shows the effect of [NBE]0/[Co] ratio on the
polymerization of NBE with 4/d-MAO system. Poly-
mer yields were decreased in the polymerizations for 3
h under the high [NBE]0/[Co] ratio, while the poly-
merizations for 12 h afforded polymers in good yield
even under high [NBE]0/[Co] ratio. Increasing of the
[NBE]0/[Co] ratio resulted in an increase of number
average molecular weights (Mn) of PNBE. The mo-
lecular weight distributions of these polymers re-
mained relatively narrow (< 2) and Mn were close to
the theoretical value calculated from feed [NBE]0/[Co]
ratio, especially the polymerization under [NBE]0/[Co]
ratio of 1170 mol/mol. These results indicate that this
polymerization system has a potential to proceed the
living polymerization.
3
12
41
88
4.6
4.2
1.70
1.49
6
CoCl2
3
12
3
17
38
6.1
7.7
1.59
1.36
b
–
Trace
Conditions; Cat. ¼ 0.02 mmol, Cocat. ¼ d-MAO, [Al]/[Co] ¼ 100
mol/mol, [NBE]0/[Co] ¼ 214 mol/mol, Solvent ¼ 5 ml of chloroben-
zene, Temp. ¼ r.t.
a Determined by GPC calibrated with standard polystyrenes at
40 °C, eluent CHCl3.
b Without cobalt complex.
were not suitable for polymerization of NBE. Thus the
polymer yield was distinctly low in 6/d-MAO system.
In spite of the steric hindrance of the methyl groups
at 6- and 600-positions of terpyridine group, the complex
4 was most active among these cobalt systems. Fig. 5
shows space filling models of complexes 1, 3, and 4. The
6,600-methyl groups exist close to the metal center, and
this should prevent association of d-MAO anions with
cationic species. Thus the loose ionic pair would be
formed which is favorable for coordination and inser-
tion of norbornene monomer. Moreover, the complex 4
has pseudo trigonal bipyramidal structure. If the coor-
dination sphere is maintained in polymerization system,
both the coordination sites for NBE and growing
The introduction of bulkier alkyl groups into ter-
pyridine is now under investigation.
Fig. 4. 1H NMR spectrum of poly(NBE) obtained with 4/d-MAO shown in Table 2 (polymerization time ¼ 12 h).

748
Y. Sato et al. / Journal of Organometallic Chemistry 689 (2004) 744–750
Table 3
Effect of monomer ratio on the polymerization of NBE with 4/d-MAO system
M
nðcalcd:Þ ꢁ 10ꢂ4
[NBE]0/[Co]
[mol]/[mol]
3 h
12 h
Yield (%)
M
nðfoundÞ ꢁ 10ꢂ4a
Mw=Mn
Yield (%)
M
nðfoundÞ ꢁ 10ꢂ4a
Mw=Mn
a
a
117
214
1.1
>99
>99
86
3.3
1.63
1.61
1.54
1.74
1.66
1.69
>99
>99
95
4.0
1.42
1.36
1.94
1.73
1.73
1.70
2.0
3.3
3.2
6.5
4.5
5.9
351
468
4.4
7.7
88
75
8.7
95
98
9.1
819
1170
10.4
14.6
10.7
13.8
11.0
48
85
Conditions; Cat. ¼ 0.02 mmol, Cocat. ¼ d-MAO, [Al]/[Co] ¼ 100 mol/mol, Solvent ¼ 5 ml of chlorobenzene, Temp. ¼ r.t.
a Determined by GPC calibrated with standard polystyrenes at 40 °C, eluent CHCl3.
3. Conclusion
4.2. Materials
A series of cobalt(II) complexes having terpyridine
ligands such as CoCl2(Tpy) (1), CoC2(4,40 ,400-tBu3-Tpy)
(2), CoCl2(5,500-Me2Tpy) (3), CoCl2(6,600-Me2Tpy) (4)
and CoCl2[6,600-(3,5-Me2C6H3)2-Tpy] (5) was synthe-
sized. The structures of 1, 3, and 4 were confirmed by X-
ray crystallography and complex 4 had pseudo trigonal
bipyramidal structure. Upon activation with d-MAO,
these complexes showed high activities for the poly-
merization of norbornene (NBE). In particular, the
polymerization of NBE with 4/d-MAO system at room
temperature resulted in quantitative yield. The molecu-
lar weights of the polymers were controllable by the feed
[NBE]0/[Co] ratio and the resulting molecular weight
distributions were relatively narrow. As far as we know
this is the first example of controlled vinyl-type poly-
merization of NBE with cobalt complexes.
Tetrahydrofuran (THF) was dried over Na–K alloy
and distilled before use. CoCl2, 2,6-dibromopyridine,
and norbornene were purchased form Kanto Chemical
Co. 2,20 :60 ,200-terpyridine and 4,40 ,400-tri-tert-butyl-2,20 :
60 ,200-terpyridine were purchased from Aldrich Chemi-
cal Company Inc. NBE was dried over CaH2 and then
over a dried molecular sieve 4A. MAO (methylalumi-
noxane) and MMAO (modified MAO) were supplied by
Tosoh Fine Chemistry, Co. and used without further
purification.
4.3. Synthesis of CoCl2(4,40 ,400-tri-tert-butyl-2,20 :60 ,200-
terpyridine) (2)
A mixture of CoCl2 (0.50 g, 3.90 mmol), 4,40 ,400-tri-
tert-butyl-2,20 :60 ,200-terpyridine (1.57 g, 3.90 mmol), and
45 ml of THF was placed in a 100 ml two neck round
flask. The mixture was stirred for 12 h at 25 °C, resulting
in the formation of a green suspension. The green pre-
cipitates were collected by centrifugation and washed
with THF followed by drying in vacuo. CoCl2(4,40 ,400-
tri-tert-butyl-2,20 :60 ,200-terpyridine) (2) was obtained as a
green powder. Yield: 80% (1.65 g, 3.10 mmol). Anal.
Calcd. for C27H35N3CoCl2: C, 61.02; H, 6.64; N, 7.91.
Found: C, 61.39; H, 6.92; N, 8.62%.
4. Experimental
4.1. General considerations
All operations were performed under argon by using
standard Schlenk techniques. 1H NMR spectra were
recorded on a JEOL JNM-LA-400 spectrometer (400
MHz), and chemical shifts were calibrated with residual
chloroform (d ¼ 7:26 ppm) in CDC13. 1H NMR spectra
of poly(NBE)s were measured using a mixture of o-
dichlorobenzene and benzene-d6 (4:1) as a solvent at
100 °C. Elemental analyses of the cobalt complexes were
carried out on a Perkin Elmer 2400 series II CHN/O
analyzer after sealing the sample in a tin foil under ar-
gon. Gel permeation chromatographic (GPC) analyses
of PNBE were run on a Tosoh model SC-8010 instru-
ment (RI 8020 detector) with the TSK gel columns
G1000, G2500, G4000, and G7000 in chloroform at
40 °C. The number-average molecular weights (Mn) and
weight-average molecular weights (Mw) of the polymers
were determined with reference to a calibration curve
plotted with standard polystyrene.
4.4. Synthesis of CoCl2(5,500-dimethyl-2,20 :60 ,200-terpyri-
dine) (3)
A mixture of CoCl2 (0.30 g, 2.20 mmol), 5,500-di-
methyl-2,20 :60 ,200-terpyridine (0.61 g, 2.20), and 45 ml of
THF was placed in a 100 ml two neck round flask. The
mixture was stirred for 12 h at 25 °C, resulting in the
formation of a green suspension. The green precipitates
were collected by centrifugation and washed with THF
followed by drying in vacuo. CoCl2(5,500-dimethyl-
2,20 :60 ,200-terpyridine) (3) was obtained as a green pow-
der. Yield: 99% (0.84 g, 2.16 mmol). Anal. Calcd. for
C27H35N3CoCl2: C, 52.20; H, 3.87; N, 10.74. Found: C,
50.71; H, 3.86; N, 10.61%.

Y. Sato et al. / Journal of Organometallic Chemistry 689 (2004) 744–750
749
4.5. Synthesis of 6,600-dimethyl-2,20 :60 ,200-terpyridine
were collected by centrifugation and washed with THF
followed by drying in vacuo. CoCl2(6,600-dimethyl-
2,20 :60 ,200-terpyridine) (4) was obtained as a green pow-
der. Yield: 82% (0.74 g, 1.9 mmol). Anal. Calcd. for
C27H35N3CoCl2: C, 52.20; H, 3.87; N, 10.74. Found: C,
52.04; H, 3.84; N, 10.68%.
A mixture of 6-methyl-2-tributylstannylpyridine (30.5
g, 80.1 mmol), 2,6-dibromopyridine (8.1 g, 34.2 mmol),
and tetrakis(triphenylphosphine)palladium (2.4 g, 2.0
mmol) was refluxed for 4 days in absolute toluene (150
ml). After removal of the solvent, the black residue was
treated with aq. HCl solution (3 ꢁ 30 ml, 6 M). The
suspension was extracted with CH2Cl2, and the organic
phase was washed again with aqueous HCl. The aque-
ous solution was added dropwise into aqueous ammonia
(250 ml, 10%). The precipitates were filtered, dissolved
in CH2Cl2, treated with activated carbon, and dried over
MgSO4. The solvent was removed in vacuo to give 6,600-
dimethyl-2,20 :60 ,200-terpyridine as a white powder. Yield:
80% (7.1 g, 27.2 mol). Anal. Calcd. for C27H35N3: C,
78.13; H, 5.79; N, 16.08. Found: C, 78.05; H, 5.78; N,
16.02%.
4.7. Synthesis of CoCl2[6,600-(3,5-Me2C6H3)-2,20 :60 ,200-
terpyridine] (5)
A mixture of CoCl2 (0.2 g, 2.0 mmol), 6,600-(3,5-
Me2C6H3)-2,20 :60 , 200-terpyridine (0.9 g, 2.0 mmol), and
45 ml of THF was placed in a 100 ml two neck round
flask, and stirred for 12 h at 25 °C, resulting in the
formation of a green suspension. The green precipitates
were collected by centrifugation and washed with THF
followed by drying in vacuo. CoCl2[6,600-(3,5-Me2Ph)-
2,20 :60 ,200-terpyridine] (5) was obtained as a green pow-
der. Yield: 28% (0.31 g, 0.6 mmol). Anal. Calcd. for
C31H27N3CoCl2: C, 65.16; H, 4.76; N, 7.35. Found: C,
65.17; H, 5.33; N, 7.08%.
4.6. Synthesis of CoCl2(6,600-dimethyl-2,20 :60 ,200-terpyri-
dine) (4)
A mixture of CoCl2 (0.3 g, 2.3 mmol), 6,600-dimethyl-
2,20 :60 ,200-terpyridine (0.6 g, 2.3 mmol), and 45 ml of
THF was placed in a 100 ml two neck round flask. The
mixture was stirred for 12 h at 25 °C, resulting in the
formation of a green suspension. The green precipitates
4.8. Polymerization of norbornene
A solution of d-MAO in chlorobenzene (1.2 ml, 4 M)
was added to a solution of cobalt complex (0.02 mmol)
in chlorobenzene (5 ml) at ambient temperature or 0 °C
Table 4
Crystal data and data collection parameters
Complex 1
Complex 3
Complex 4
Empirical formula
Formula weight
Temperature/°C
Color
C15H11N3CoCl2
363.11
23
C17H15N3CoCl2
391.16
23
C17H15N3CoCl2
391.16
)150
Green
Green
Green
Crystal dimensions/mm
Crystal system
Space group
0.10 ꢁ 0.10 ꢁ 0.10
Monoclinic
P1=c (#14)
10.8405(3)
8.2395(3)
16.1844(6)
90
0.20 ꢁ 0.20 ꢁ 0.10
Monoclinic
P1=n (#14)
9.9660(2)
14.5933(3)
11.6216(3)
90
0.15 ꢁ 0.10 ꢁ 0.10
Monoclinic
P1=c (#14)
7.353(1)
ꢀ
a/A
ꢀ
b/A
17.489(2)
12.718(1)
90
ꢀ
c/A
a/°
b/°
c/°
95.043(1)
90
103.2871(7)
90
102.360(5)
90
3
ꢀ
V /A
1440.00(8)
4
1.675
1644.96(6)
4
1.579
1597.6(4)
4
1.626
Z
D
calc/g cmꢂ3
l (Mo KaÞ/cmꢂ1
15.57
Rigaku RAXIS-RAPID
13.69
Rigaku RAXIS-RAPID
14.095
Rigaku RAXIS-RAPID
Diffractometer
Radiation
ꢀ
ꢀ
ꢀ
Mo Ka (k ¼ 0:71069 A)
Mo Ka (k ¼ 0:71069 A)
Mo Ka (k ¼ 0:71069 A)
2hmax/°
54.9
3541
3307
236
55.0
55.0
Number of measured reflections
Number of unique reflections
Number of variables
15381
3734
270
15219
3675
270
a
R1
0.090
0.170
1.02
0.044
0.090
1.09
0.041
0.111
1.14
b
wR2
GOF
P
P
a R1 ¼ jjFoj ꢂ jFcj= jFoj, for all I > 2rðIÞ.
h
i
1=2
P
P
2
2
b wR2 ¼
ðwðFo2 ꢂ Fc2Þ Þ= wðFo2Þ
:

750
Y. Sato et al. / Journal of Organometallic Chemistry 689 (2004) 744–750
and maintained for 5 min. A prescribed amount of NBE
solution in chlorobenzene was added at room tempera-
ture to start polymerization. The reaction mixture was
stirred for a given period. The polymerization mixture
was quenched with a large amount of methanol/hydro-
chloric acid mixture. The precipitated polymers were
collected by centrifugation and dried in vacuo. The
number average molecular weights (Mn) and molecular
weight distributions (Mw=Mn) of the polymers were de-
termined by gel permeation chromatography (GPC).
obtained free of charge from The Director, CCDC, 12
Union Road, Cambridge CB2 1EZ, UK (Fax: +44-1223-
336033 or e-mail: deposite@ccdc.cam.ac.uk or www:
http://www.ccdc.cam.ac.uk).
References
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ration Properties and Technology, John Wiley & Sons, New York,
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[3] L.K. Jonson, C.M. Killian, M. Brookhart, J. Am. Chem. Soc. 117
(1995) 6414.
4.9. X-ray structure determination
Single crystals of 1, 3 and 4 suitable for X-ray dif-
fraction were mounted in a cryoloop. Measurements of
these crystals were made on a Rigaku RAXIS RAPID
Imaging Plate for data collection using Mo Ka radia-
tion. Crystal data and data collection parameters of
these complexes are summarized in Table 4. Indexing
was performed from three oscillations which were ex-
posed for 3.0 min. The camera radius was 127.40 mm.
Readout was performed in the 0.10 mm pixel mode. A
linear absorption coefficient, l, was applied. The data
were corrected for Lorentz and polarization effects. The
structures were solved by direct methods (SHELX-86 [12]
for 1, SHELX-97 [13] for 3 and 4), and expanded using
Fourier techniques (DIRDIF99) [14]. The data were
refined by the full-matrix least-square method. All the
non-hydrogen atoms were refined anisotropically. Hy-
drogen atoms for each complex were refined using the
riding model. The final cycle of full-matrix least-squares
refinements was performed on F 2. All calculations were
performed using the CrystalStructure [15,16] crystallo-
graphic software package except for refinement, which
was performed using SHELXL-97 [13].
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(1998) 1627.
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120 (1998) 4049.
[12] G.M. Sheldrick, in: G.M. Sheldrick, C. Kruger, R. Goddard
(Eds.), Crystallographoc Computing 3, Oxford University Press,
Oxford, 1985, p. 175.
[13] G.M. Sheldrick, Program for the Solution of Crystal Structure,
€
5. Supplementary material
University of Gottingen, Germany, 1997.
[14] P. Beurskens, G. Admiraal, G. Beurskens, W. Bosman, R.
deGelder, R. Israel, and J. Smits, The DIRDIF99 program
system, Technical report of the Crystallography Laboratory,
University of Nijmegan, The Netherlands, 1999.
Crystallographic data for the structural analysis of
1, 3, and 4 have been deposited with the Cambridge
Crystallographic0 Data Centre, CCDC No. 210854
for CoCl2(2,20 :6 ,200-terpyridine) (1), No. 210855 for
CoCl2(5,500-Me2-2,20 :60 ,200-terpyridine) (3), and No.
210856 for CoCl2(6,600-Me2-2,20 :60 ,200-terpyridine) (4),
respectively. Copies of these information may be
[15] CrystalStructure 3.10, Crystal Structure Analysis Package, Rigaku
and Rigaku/MSC, 2000-2002.
[16] Watkin, D.J., Prout, C.K., Carruthers, J.R., Betteridge, P.W.
CRYSTALS Issue 10, Chemical Crystallography Laboratory, Ox-
ford, UK.