Ethylene and ethylene/1-hexene (co)polymerizations with 2,5-dimethylcyclopentadienyl ansa-titanocene and zirconocene complexes

Article abstract of DOI:10.1016/j.poly.2005.02.015

C1-bridged 2,5-dimethylcylcopentadienyl ansa-titanocene complexes, [Me(H)C(η⁵-C₅H₄)(η⁵-2,5- Me₂C₅H₂)]TiCl₂ (4) and [(CH ₃CH₂CH₂)(H)C(η⁵-C ₅H₄)(η⁵-2,5-Me₂C ₅H₂)]TiCl₂ (5) and a dinuclear titanium complex, Me₂Si[(η⁵-2,5-Me₂C ₅H₂)Ti{O(2,6-iPr₂C₆H ₃)}Cl₂] (7) have been prepared. The solid state structure of 4 has been determined by X-ray crystallography. Ethylene polymerization reactivities of 4, 5, 7 and the structurally related ansa-zirconocene complexes, [Me(H)C(η⁵-C₅H₄)(η⁵-2,5- Me₂C₅H₂)]ZrCl₂ (1), [(Me)(H)C(η⁵-2,5-Me₂C₅H₂) ₂]ZrCl₂ (2) and [Me₂Si(η⁵-2,5- Me₂C₅H₂)₂]ZrCl₂ (3) are investigated after activation with MAO. Interestingly, the ansa-titanocene complexes 4 and 5 show much higher activity than the ansa-zirconocene complexes 1 and 2, and the molecular weights of the polymers obtained by the titanocene complexes are significantly higher (M_w, ～800 000) than those of polymers obtained by the zirconocene complexes (M_w, below 200 000). The Me₂Si-bridged complex 3 shows extremely high activity for ethylene polymerization and the activity (290 × 10⁶ g/mol h) is 15 times higher than that of [Me₂Si(Me₄C ₅)(NtBu)]TiCl₂ (CGC) under the same conditions. Ethylene/1-hexene copolymerization reactivities of 3 and 5 have been studied. The complexes are inferior to CGC in terms of comonomer incorporation ability.

Full text of DOI:10.1016/j.poly.2005.02.015

Polyhedron 24 (2005) 1256–1261
www.elsevier.com/locate/poly
Ethylene and ethylene/1-hexene (co)polymerizations with
2,5-dimethylcyclopentadienyl ansa-titanocene
and zirconocene complexes
*
Ui Gab Joung, Bun Yeoul Lee
Department of Molecular Science and Technology, Ajou University, San 5 Wonchondong, Suwon 442-749, Republic of Korea
Received 4 January 2005; accepted 21 February 2005
Available online 13 April 2005
Abstract
C1-bridged 2,5-dimethylcylcopentadienyl ansa-titanocene complexes, [Me(H)C(g5-C5H4)(g5-2,5-Me2C5H2)]TiCl2 (4) and
[(CH3CH2CH2)(H)C(g5-C5H4)(g5-2,5-Me2C5H2)]TiCl2 (5) and a dinuclear titanium complex, Me2Si[(g5-2,5-Me2C5H2)Ti{O(2,6-
iPr2C6H3)}Cl2] (7) have been prepared. The solid state structure of 4 has been determined by X-ray crystallography. Ethylene poly-
merization reactivities of 4, 5, 7 and the structurally related ansa-zirconocene complexes, [Me(H)C(g5-C5H4)(g5-2,5-Me2C5H2)]ZrCl2
(1), [(Me)(H)C(g5-2,5-Me2C5H2)2]ZrCl2 (2) and [Me2Si(g5-2,5-Me2C5H2)2]ZrCl2 (3) are investigated after activation with MAO.
Interestingly, the ansa-titanocene complexes 4 and 5 show much higher activity than the ansa-zirconocene complexes 1 and 2,
and the molecular weights of the polymers obtained by the titanocene complexes are significantly higher (Mw, ꢀ800 000) than those
of polymers obtained by the zirconocene complexes (Mw, below 200 000). The Me2Si-bridged complex 3 shows extremely high
activity for ethylene polymerization and the activity (290 · 106 g/mol h) is 15 times higher than that of [Me2Si(Me4C5)(NtBu)]TiCl2
(CGC) under the same conditions. Ethylene/1-hexene copolymerization reactivities of 3 and 5 have been studied. The complexes are
inferior to CGC in terms of comonomer incorporation ability.
ꢀ 2005 Elsevier Ltd. All rights reserved.
Keywords: Metallocenes; Titanium; Zirconium; Polymerization; Cyclopentadienyl
1. Introduction
enhanced without increasing the steric hindrance at the
active site. The complexes show excellent activity for
the copolymerization of ethylene and bulky comonomer
such as norbornene [3]. It is generally accepted that the
titanocene complexes show inferior activity to the corre-
sponding zirconocene complexes but recently there have
been some reports that Me2Si-bridged and C1-bridged
titanocene complexes show higher activities than the
corresponding ansa-zirconocene complexes [6]. These
reports prompted us to synthesize Me2Si-bridged and
C1-bridged 2,5-dimethylcylcopentadienyl titanocene
complexes with ligands that had been successfully used
in the preparation of zirconocene complexes in our
group. Herein, we report the synthesis of the titanium
complexes and their ethylene and ethylene/1-hexene
(co)polymerization reactivities.
The development of Group 4 metallocene catalysts
for olefin polymerization remains an active research area
in both academic and industrial fields [1]. Merits of these
metallocene-based catalysts are the tunability of activity,
comonomer incorporation and polymer microstructure
by the ligand structure [2]. We have reported several
kinds of 2,5-dimethylcylcopentadienyl-based ansa-zirc-
onocene complexes (1–3) [3–5]. By placing the two
methyl substituents proximal to the bridgehead carbon,
the p-donor ability of the cyclopentadienyl ring can be
*
Corresponding author. Tel.: +823 121 91844; fax: +823 121 91592.
E-mail address: bunyeoul@ajou.ac.kr (B. Yeoul Lee).
0277-5387/$ - see front matter ꢀ 2005 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2005.02.015

U. Gab Joung, B. Yeoul Lee / Polyhedron 24 (2005) 1256–1261
1257
Me
Me
Me
Me
Me
Me
effectively as catalysts for olefin polymerizations [7], the
dinuclear Me2Si[(g5-2,5-Me2C5H2)Ti{O(2,6-iPr2C6H3)}
Cl2]2 (7) has been prepared (Eq. (2)). Recently, dinuclear
CGC-type complexes have drawn extensive attention
because of their enhanced reactivity compared to the
mononuclear counterparts [8]. Thus, addition of two
equivalents of TiCl2(NMe2)2 to the dilithium salt
provides cleanly the desired dinuclear complex, Me2-
Si[(g5-2,5-Me2C5H2)Ti(NMe2)2Cl]2, which is cleanly
transformed to the trichloride complex by treatment with
Me2SiCl2 (overall yield from the dilithium salt, 75%).
Addition of 2,6-diisopropylphenoxypotassium to the tri-
chloride complex affords the desired complex 7 in 86%
Me
Me
Me
Me
Me
Me
Me
ZrCl2
ZrCl2
ZrCl2
Si
Me
1
2
3
2. Results and discussion
2.1. Syntheses and characterizations
The C1-bridged ansa-titanocene
complex
[Me(H)C(g5-C5H4)(g5-2,5-Me2C5H2)]TiCl2 (4) was pre-
pared using the ligand of ansa-zirconocene complex 1
[3]. Thus, the reaction of the dilithium salt with
TiCl2(NMe)2 in pyridine afforded the desired bis(dime-
thylamido)titanium complex which was transformed to
the dichloride complex 4 by treatment with Me2SiCl2
(Eq. (1)). The overall yield from the dilithium salt
1
yield. The H and 13C NMR spectra and the elemental
analysis data are in agreement with the structure.
Me
i) TiCl2(NMe2)2
ii) Me2SiCl2
Me
Me
Me
Me
Li+
Si
2
was rather low (28%). The H and 13C NMR spectra
1
are in agreement with the structure. Two doublet sig-
nals are observed for Me2Cp–H protons at 6.67 and
6.64 ppm (J = 3.6 Hz) and four Cp–H signals are ob-
served at 6.67, 6.83, 5.45 and 5.18 ppm in the 1H
NMR spectrum. The bridge-CH signal is observed at
3.90 ppm as a quartet. The complex is sparingly soluble
in benzene or toluene. Complex [(CH3CH2CH2)(H)-
C(g5-C5H4)(g5-2,5-Me2C5H2)]TiCl2 (5) was synthesized
by almost the same method and conditions applied for
the synthesis of 4. The overall yield from the dilithium
salt was 50%. The complex is freely soluble in toluene.
The Cp–H and Me2Cp–H signal pattern is identical to
that observed for 4 and the bridge-CH signal is ob-
served at 3.60 ppm as a triplet.
Me
Me
Me
Me Me
Si
Me
Me
Me Me
Si
Ar'OK
Me
Me
Me
Me
Ti
Ti
Ti
Cl
Ti
Ar'O
Cl
Cl
OAr'
Cl
Cl
Cl
Cl
Cl
Cl
Cl
7
6
Ar' = 2,6-iPr2C6H3
ð2Þ
Attempts to prepare the ansa-titanocene complex
using the ligand of 2 were unsuccessful. The main prod-
uct of the reaction between the ligand and TiCl2(NMe2)2
was a dinuclear bis(dimethylamido)(chloro)titanium
complex, as observed for the ligand of 3. This failure
might be attributed to the repulsion between the methyls
attached on each cyclopentadienyl ring. The repulsion
between the methyls was observed even in the solid
structure of zirconium complex 2 [3]. Because the titano-
cene complexes have smaller metal–Cp distances, more
severe repulsion is expected for the desired ansa-titano-
cene complex, which may hamper the formation of the
ansa-complex. In the case of ansa-titanocene complexes
4 and 5, that kind of repulsion does not exist due to the
presence of methyl groups on only one cyclopentadienyl
ligand, consequently allowing formation of the desired
ansa-complexes.
Single crystals of 4 suitable for Xray crystallography
were deposited in the reaction pot when the bis(dimethy-
lamido) titanium complex was reacted with Me2SiCl2 in
the absence of stirring and its structure was confirmed
by X-ray crystallographic studies. The ORTEP drawing
with selected bond distances and angles are shown in
Fig. 1. It shows a characteristic strained ansa-metallo-
cene structure: small angle of Cp(c)–Ti–Cp(c) (Cp(c),
centroid of Cp), deviation of Cb–C–Cb (Cb, bridgehead
carbon on Cp) angle from the ideal tetrahedral value
Me
R
Me
R
i) TiCl2(NMe2)2
ii) Me2SiCl2
Me
2
Me
TiCl2
Li+
4: R = Methyl
5: R= Propyl
ð1Þ
Attempts to prepare the ansa-titanocene complex
using the ligand of 3 were unsuccessful. The major prod-
uct is a dinuclear complex when equimolar amount of
the dilithium salt and TiCl2(NMe2)2 are reacted even un-
der fairly dilute conditions (Eq. (2)). Only four singlet
signals are observed at 5.80 (Cp–H), 3.11 (NCH3),
2.01 (CH3) and 1.03 (SiCH3) ppm with an integration
1
ratio of 2:12:6:3 in the H NMR spectrum. The integra-
tion ratio strongly supports the formation of a dinuclear
complex. The same kind of dinuclear titanium complex
was obtained when the dilithium salt of methylene-
bridged 2,5-dimethylcyclopentadienyl indenyl ligand
was reacted with an equimolar amount of TiCl2(NMe2)2
[5]. Because unbridged cyclopentadienyl phenoxy tita-
nium dichloride complexes have been reported to serve

1258
U. Gab Joung, B. Yeoul Lee / Polyhedron 24 (2005) 1256–1261
Table 1
Ethylene polymerization results of 1–7 and CGCa
Complex Time Temperature Activity
(min) (ꢁC)b (10ꢁ6 g/mol h)
Mw
Mw/Mn
1
10
10
80
80
93
89
87
80
80
80
15
36
183 000 12
2
68 000
232 000
796 000
770 000
4.0
3
2.5
288
100
2.8
2.4
3.1
4
5
2.5
5
125
6
10
negligible
negligible
20
7
CGC
10
10
129 000
2.5
a
Polymerization conditions: 100 psig ethylene, 30 mL toluene,
0.25 lmol catalyst, Al/Zr = 6000, initial temperature 80 ꢁC.
Final temperature.
b
Cb–C(bridge)–Cb angle (95.5(12)ꢁ) is more strained in
4 than the corresponding angle is in 1 (100.7(4)ꢁ). The
methyl group attached on the cyclopentadienyl is out
of the cyclopentadienyl plane as much as the methyl is
in 1 (the H3C–C–Cp(c) angle for 1 and 4, 175.5ꢁ and
176.0ꢁ, respectively).
Fig. 1. Thermal ellipsoid plot (30% probability level) of the structure
˚
of 4. Selected bond distances (A) and angles (ꢁ): Ti–C(1), 2.355(18); Ti–
C(2), 2.336(11); Ti–C(3), 2.408(13); Ti–C(5), 2.323(17); Ti–C(6),
2.371(13); Ti–C(7), 2.411(15); Ti–Cl, 2.343(4); Cp(c)–Ti, 2.043;
Me2Cp(c)–Ti, 2.060; Cl–C–Cl, 98.7(2); Me2Cp(c)–Ti–Cp(c), 120.4;
C(1)–C(4)–C(5), 95.5(12).
2.2. Polymerization studies
The complexes 1–7 were studied for ethylene poly-
merization after activation with MAO (Table 1). The
C1-bridged zirconocene complexes 1 and 2 show similar
activities to [Me2Si(Me4C5)(NtBu)]TiCl2 (CGC), but the
titanocene complexes 4 and 5 show much higher activi-
ties than CGC. The Me2Si-bridged complex 3 shows
extremely high activity for ethylene polymerization.
The activity is 15 times higher than that observed for
CGC under the same conditions. The dinuclear com-
plexes 6 and 7 show negligible activity under the same
conditions. Interestingly, the molecular weights of the
polymers obtained by the titanocene complexes 4 and
5 are significantly higher (Mw, ꢀ800 000) than those of
of 109.5ꢁ, increase of C–Ti bond distances on going
from bridgehead carbon to peripheral carbons. The
˚
Cp(c)–Ti and Me2Cp–Ti distances (2.043 and 2.060 A,
respectively) are smaller than those observed for the cor-
˚
responding zirconium complex 1 (2.188 and 2.186 A,
respectively) [3]. The Me2Cp(c)–Ti–Cp(c) angle, which
measures how far the metal is displaced from the cyclo-
pentadienyl ligand, is smaller (120.4ꢁ) in 4 than the cor-
responding angle in 1, indicating that the titanium atom
is displaced more closely to the mouth of the cyclopen-
tadienyl ligands and that, consequently, the reaction site
is opened less in 4. The Cl–Ti–Cl angle is smaller
(98.2(7)ꢁ) than that observed for 1 (102.11(7)ꢁ). The
Table 2
Ethylene/1-hexene copolymerization results of 3, 5 and CGCa
Entry
Complex
1-Hexene (mol/L)
Time (min)
Temperature (ꢁC)b
Tm (ꢁC)
Activity (10ꢁ6 g/mol h)
Mw
Mw/Mn
1
2
3
0.10
0.20
0.30
0.40
0.50
0.10
0.20
0.30
0.40
0.50
0.30
5
5
93
96
96
94
95
79
82
82
80
79
87
117
115
105c
104
102
120
107
105d
106
105
n.d.e
132
139
150
139
143
35
210 000
191 000
160 000
152 000
174 000
537 000
356 000
291 000
281 000
237 000
279 000
3.0
2.9
2.4
2.6
2.8
2.2
2.3
2.2
3.2
2.3
2.4
3
3
3
5
4
3
5
5
3
5
6
5
5
7
5
5
37
36
8
5
5
9
5
5
32
31
10
11
a
5
CGC
10
5
35
Polymerization conditions: 60 psig ethylene, 30 mL toluene, 0.25 lmol catalyst, Al/Zr = 8000, initial temperature 80 ꢁC.
Final temperature.
b
c
3 mol% of 1-hexene content by the 13C NMR analysis.
d
e
4 mol% of 1-hexene content by the 13C NMR analysis.
14 mol% of 1-hexene content by the 13C NMR analysis.

U. Gab Joung, B. Yeoul Lee / Polyhedron 24 (2005) 1256–1261
1259
polymers obtained by the zirconocene complexes 1, 2
and CGC.
Conley Gas (99.9%) and purified by contact with molec-
ular sieves and copper overnight under a pressure of
150 psig. Methylaluminoxane (MAO) was purchased
as a solution in toluene from Akzo (7.6 wt% of Al,
MMAO type 4). TiCl2(NMe2)2 was prepared according
to the literature method [10]. NMR spectra were re-
corded on a Varian Mercury plus 400 or Bruker spec-
trometer. Elemental analyses were carried out at the
Inter-University Center Natural Science Facilities, Seoul
National University. Gel permeation chromatograms
(GPC) were obtained at 140 ꢁC in trichlorobenzene
using Waters Model 150-C+ GPC and the data were
analyzed using a polystyrene analyzing curve. Differen-
tial scanning calorimetry (DSC) was performed on a
Thermal Analysis 3100.
The ethylene/1-hexene copolymerization reactivities
were investigated for the highly active complexes 3 and
5 (Table 2). Complex 3 shows still higher activity than
CGC but in the case of the titanocene complex 5, the
activity reduces to the level of CGC by the addition of
1-hexene. The 1-hexene incorporation ability of 3 and 5
is inferior to that of CGC. Polymers containing 3 and
4 mol% of 1-hexene are obtained by 3 and 5, respectively,
but CGC gives a polymer containing 14 mol% of 1-hex-
ene under the same conditions (entries 3, 8 and 11) [9].
The Tm value is correlated with the 1-hexene incorpora-
tion. With the initial increase of the 1-hexene feeding
amount, the Tm value decreases but a plateau is observed
above 0.3 M of 1-hexene feeding for both 3 and 5, which
implies that the 1-hexene incorporation is limited to
some extent and that it cannot be easily increased above
that value merely by increasing the 1-hexene feed
amount. The molecular weight is reduced not only by
the addition of 1-hexene but also with the increase of
the 1-hexene feeding for complex 5, implying 1-hexene
acts as a chain transfer agent in this catalyst system.
4.2. Synthesis of [Me(H)C(g5-C5H4)(g5-2,5-Me2C5H2)]
TiCl2 (4)
TiCl2(NMe2)2 (0.209 g, 1.01 mmol) and the dili-
thium salt [Me(H)C(C5H4)(2,5-Me2C5H2)]Li2 (0.200 g,
1.01 mmol) were weighed in a vial inside a glove
box. Cold pyridine (2.5 mL, ꢁ20 ꢁC) was added and
the resulting mixture was stirred for 3 min at room
temperature. The solvent was removed to give a resi-
due which was dissolved in benzene. The solution
was filtered and the solvent was removed by vacuum
to give a red oily residue which was used for the next
3. Conclusion
C1-bridged 2,5-dimethylcyclopentadienyl ansa-titano-
cene complexes, [Me(H)C(g5-C5H4)(g5-2,5-Me2C5H2)]-
TiCl2 (4) and [(CH3CH2CH2)(H)C(g5-C5H4) (g5-2,5-
Me2C5H2)]TiCl2 (5) show much higher activity for ethyl-
ene polymerization than the corresponding ansa-zircono-
cene complex [Me(H)C(g5-C5H4)(g5-2,5-Me2C5H2)]-
ZrCl2 (1) and the molecular weights of the obtained
polymers are significantly higher (Mw, ꢀ800 000) than
those of polymers obtained with the zirconocene com-
plex 1. The Me2Si-bridged complex [Me2Si(g5-2,5-
Me2C5H2)2]ZrCl2 (3) shows extremely high activity
for ethylene polymerization and the activity is 15 times
higher than that of [Me2Si(Me4C5)(NtBu)]TiCl2 (CGC).
However, Complexes 3 and 5 are inferior to CGC in
terms of comonomer incorporation ability in ethylene/
1-hexene copolymerization.
1
reaction without further purification. H NMR (pyri-
dine-d5): d 6.44 (quartet, J = 2.0 Hz, 1H, Cp–H),
6.37 (quartet, J = 2.0 Hz, 1H, Cp–H), 6.18 (d,
J = 3.2 Hz, 1H, Me2Cp–H), 6.12 (d, J = 3.2 Hz, 1H,
Me2Cp–H), 5.48 (quartet, J = 2.0 Hz, 1H, Cp–H),
5.17 (quartet, J = 2.0 Hz, 1H, Cp–H), 3.86 (quartet,
J = 7.2 Hz, 1H, CHCH3), 2.98 (s, 6 H, NCH3), 2.97
(s, 6H, NCH3), 2.07 (s, 3H, CH3), 1.95 (s, 3H,
CH3), 1.61 (d, J = 7.2 Hz, 3H, CHCH3) ppm. The
bis(dimethylamido)titanium complex was dissolved in
benzene (1.5 mL) and Me2SiCl2 (0.39 mL, 3.0 mmol)
was added. The solution was stirred for 1 h to give
dark brown precipitates, which were collected by fil-
tration. The solid was pure by analysis of the 1H
and 13C NMR spectra (0.085 g; overall yield, 28%).
Single crystals suitable for X-ray crystallography were
deposited when the bis(dimethylamido) complex was
reacted with Me2SiCl2 in the absence of stirring. 1H
4. Experimental
NMR (C6D6:pyridine-d5, 10:1):
d
6.76 (quartet,
4.1. General considerations
J = 2.8 Hz, 1H, Cp–H), 6.83 (quartet, J = 2.8 Hz,
1H, Cp–H), 6.67 (d, J = 3.6 Hz, 1H, Me2Cp–H), 6.64
(d, J = 3.6 Hz, 1H, Me2Cp–H), 5.45 (dd, J = 3.6,
2.8 Hz, 1H, Cp–H), 5.18 (dd, J = 3.6, 2.8 Hz, 1H,
Cp–H), 3.90 (quartet, J = 7.2 Hz, 1H, CHCH3), 1.83
(s, 3H, CH3), 1.67 (s, 3H, CH3), 1.40 (d, J = 7.2 Hz,
1H, CHCH3) ppm. 13C NMR (C6D6:pyridine-d5,
All manipulations were performed under an inert
atmosphere using standard glove box and Schlenk tech-
niques. Toluene, pentane, THF and C6D6 were distilled
from benzophenone ketyl. Pyridine was dried over
CaH2. Toluene used for polymerization reactions was
purchased from Aldrich (anhydrous grade) and purified
further over Na/K alloy. Ethylene was purchased from
10:1): d 133.88, 132.32, 131.58, 129.95, 126.70,
124.89, 111.91, 111.36, 109.28, 102.59, 32.43, 18.78,

1260
U. Gab Joung, B. Yeoul Lee / Polyhedron 24 (2005) 1256–1261
16.22, 15.87 ppm. Anal. Calc. for C14H16Cl2Ti: C,
55.48; H, 5.33. Found: C, 55.11; H, 5.53%.
solvent was removed by vacuum. Toluene (10 mL) was
added and the solution was filtered over Celite. Removal
of solvent gave a red residue which was triturated in
pentane. The obtained solid was pure by the analysis
4.3. Synthesis of [(CH3CH2CH2)(H)C(g5-C5H4)-
(g5-2,5-Me2C5H2)]TiCl2 (5)
of the H and 13C NMR spectra. H NMR (C6D6): d
5.80 (s, 4H, Cp–H), 3.11 (s, 24H, NCH3), 2.01 (s, 12H,
CH3), 1.03 (s, 6H, SiCH3). 13C NMR (C6D6): d
134.68, 123.33, 116.47, 48.60, 17.23, 3.50. The residue
was dissolved in toluene (10 mL) and excess Me2SiCl2
(ꢀ2 mL) was added. The solution was stirred for 3 h.
The solvent was removed by vacuum to give a red resi-
1
1
TiCl2(NMe2)2 (1.80 g, 8.70 mmol) was dissolved in tol-
uene (10 mL) and the dilithium salt [(CH3CH2CH2)-
HC(C5H4)(2,5-Me2C5H2)]Li2(THF)2.25 (3.38 g, 8.70 mmol)
was dissolved in a cosolvent of toluene (25 mL) and pyri-
dine (7 mL). After the two solutions were cooled in a
refrigerator (ꢁ20 ꢁC), they were rapidly combined. The
combined solution was stirred for 20 min at room temper-
ature and the solvent was removed by vacuum. The
bis(dimethylamido) complex was extracted with pentane.
Removal of the solvent gave a red residue which was pure
1
due which was triturated in pentane (0.340 g, 75%). H
NMR (C6D6:pyridine-d5, 10:1): d 6.45 (s, 4H, Cp–H),
2.05 (s, 12H, CH3), 0.79 (s, 6H, SiCH3). 13C NMR
(C6D6:pyridine-d5, 10:1): d 147.63, 135.44, 128.80,
19.95, 1.76. Anal. Calc. for C16H22Cl6Ti2Si: C, 34.88;
H, 4.03. Found: C, 34.52; H, 4.22%.
1
by analysis of the H NMR spectrum. The residue was
used for the next reaction without further purification.
1H NMR (C6D6): d 6.38 (s, 1H, Cp–H), 6.32 (s, 1H, Cp–
H), 6.13 (d, J = 2.8 Hz, 1H, Me2Cp–H), 6.08
(d, J = 2.8 Hz, 1H, Me2Cp–H), 5.22 (s, 1H, Cp–H), 5.03
(s, 1H, Cp–H), 3.61 (t, J = 7.8 Hz, 1H, bridge-CH), 3.01
(s, 6H, NCH3), 2.98 (s, 6H, NCH3), 2.05–1.93 (m, 2H,
CH2CH2CH3), 1.95 (s, 3H, CH3), 1.82 (s, 3H, CH3),
1.46 (dq, J = 14.4, 7.2 Hz, 2H, CHCH2CH2), 0.97
(t, J = 7.6 Hz, 3H, CH2CH3). The residue was dissolved
in pentane (35 mL) and Me2SiCl2 (2.25 g, 17.3 mmol)
was added. The solution was stirred for 30 min. The sol-
vent was decanted and product was dissolved in toluene.
Some impurities were deposited from the solution when
the solution was stored at room temperature for 1 day.
The precipitates were removed by filtration over Celite.
Removal of solvent gave a brown solid (1.44 g, overall
50%). 1H NMR (C6D6): d 6.73 (quartet, J = 2.8 Hz, 1H,
Cp–H), 6.65 (quartet, J = 2.8 Hz, 1H, Cp–H), 6.63 (d,
J = 4.0 Hz, 1H, Me2Cp–H), 6.60 (d, J = 4.0 Hz, 1H,
Me2Cp–H), 5.15 (dd, J = 5.2, 3.2 Hz, 1H, Cp–H), 4.99
(dd, J = 4.8, 2.4 Hz, 1H, Cp–H), 3.59 (t, J = 8.4 Hz, 1H,
bridge-CH), 1.75–1.60 (m, 2 H, CH2CH3), 1.70 (s, 3H,
CH3), 1.55 (s, 3H, CH3), 1.22 (dq, J = 14.4, 7.2 Hz, 2H,
CHCH2CH2), 0.83 (t, J = 7.6 Hz, 3H, CH2CH3). 13C
NMR (C6D6): d 133.99, 132.36, 131.90, 129.84, 127.10,
124.52, 111.69, 111.38, 109.25, 102.03, 38.48, 32.09,
21.13, 18.63, 16.11, 14.19 ppm. Anal. Calc. for
C16H20Cl2Ti: C, 58.04; H, 6.11. Found: C, 57.67; H,
6.20%.
4.5. Synthesis of Me2Si[(g5-2,5-Me2C5H2)Ti{O(2,6-
iPr2C6H3)}Cl2]2 (7)
To a flask containing 6 (0.247 g, 0.448 mmol) and
cold toluene (5 mL, ꢁ20 ꢁC) was added KO(2,6-
iPr2C6H3) (0.165 g, 0.896 mmol), which was prepared
by treatment of KH with the corresponding alcohol
in THF. The solution was stirred for 2 h and filtered
over Celite. The solvent was removed by vacuum to
give a yellow residue which was triturated in pentane.
The yield was 0.320 g (86%). 1H NMR (C6D6): d
7.10–6.98 (m, 6H), 5.66 (s, 4H, Cp–H), 3.48 (septet,
J = 6.4 Hz, 4H, CH), 2.22 (s, 12H, CH3), 1.28 (d,
J = 6.4 Hz, 24H, CH(CH3)), 1.19 (s, 6H, SiCH3). 13C
NMR (C6D6):
d 164.49, 145.20, 138.51, 131.21,
124.90, 123.80, 122.94, 27.45, 24.08, 19.74, 2.16. Anal.
Calc. for C40H56Cl4O2SiTi2: C, 57.57; H, 6.76. Found:
C, 57.25; H, 6.58%.
4.6. Crystallographic studies
A crystal of 4, coated with grease (Apiezon N), was
mounted inside a thin glass tube with epoxy glue and
placed on an Enraf-Nonius CCD single crystal X-ray
diffractometer. The structures were solved by direct
methods (SHELXL-97) [11] and refined against all F2 data
(SHELXL-97). All non-hydrogen atoms were refined with
anisotropic thermal parameters. The hydrogen atoms
were treated as idealized contributions. Detailed struc-
tural data are given in the supplementary information.
Crystal data for 4: C14H16Cl2 Ti, M = 303.07,
4.4. Synthesis of Me2Si[(g5-2,5-Me2C5H2)TiCl3]2 (6)
˚
˚
˚
TiCl2(NMe2)2 (0.341 g, 1.65 mmol) was dissolved in
toluene (14 mL) and the dilithium salt Me2Si[(2,5-Me2-
C5H2)]Li2 Æ (THF)2 (0.300 g, 0.820 mmol) was dissolved
in a cosolvent of toluene (2 mL) and pyridine (2 mL).
After the two solutions were cooled in a refrigerator
(ꢁ20 ꢁC), they were rapidly combined. The combined
solution was stirred for 3 h at room temperature and
a = 10.962(4) A, b = 13.744(5) A, c = 9.000(3) A, Z = 4,
d = 1.485 g/cm3, orthorhombic, space group Pnma,
crystal size 0.20 · 0.15 · 0.15 mm, T = 293(2) K,
2.71 6 H 6 25.44, ꢁ12 6 h 6 13, ꢁ16 6 k 6 15, ꢁ10 6
l 6 10, 4914 measured reflections, 1281 independent
reflections (Rint = 0.2039), l = 0.999 mmꢁ1, R1 [F2 >
2r(F2)] = 0.1142, xR2 = 0.2456.

U. Gab Joung, B. Yeoul Lee / Polyhedron 24 (2005) 1256–1261
1261
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4.7. Polymerization
In a dry box, to a dried 70 mL glass reactor was
added 30 mL of toluene or 1-hexene solution in toluene.
The reactor was assembled and brought out from the
dry box. The reactor was heated to a given temperature
by mantle. After an activated catalyst, prepared by mix-
ing 0.25 lmol of catalyst and MAO (Akzo, MMAO type
4, 6.4 wt% of Al, 0.63 g (Al/Zr, 6000) or 0.84 g (Al/Zr,
8000)), was added via a syringe, ethylene (100 psig)
was fed immediately. After polymerization had been
conducted for a given time, the ethylene was vented
and acetone was added to the reactor to give white pre-
cipitates which were collected by filtration and dried un-
der vacuum.
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5. Supplementary material
Crystallographic data for structural analysis have
been deposited with the Cambridge Crystallographic
Data Center (4: CCDC No. 259500). Copies of this
information may be obtained free of charge from The
Director, CCDC, 12 Union Road, Cambridge CB2
1EZ, UK (fax: +44 1223 336033; e-mail: deposit@ccdc.
cam.ac.uk or http://www.ccdc.cam.ac.uk).
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Acknowledgments
[6] (a) S.-J. Kim, Y.-J. Lee, E. Kang, S.H. Kim, J. Ko, B.Y. Lee, M.
Cheong, I.-H. Suh, S.O. Kang, Organometallics 22 (2003) 3958;
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Macromolecules 37 (2004) 5520;
Authors give thanks for financial support from the
Whang Pill Sang research fund.
(b) K. Nomura, Y. Hatanaka, H. Okumura, M. Fujiki, K.
Hasegawa, Macromolecules 37 (2004) 1693.
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