Synthesis, structures, and catalytic properties of constrained geometry cyclopentadienyl-phenoxytitanium dichlorides

Article abstract of DOI:10.1021/om030240y

The synthesis of four new bidentate ligands, 2-(3,4-diphenylcyclopentadienyl)-6-phenylphenol ((DCPP)H₂, 7), 2-(3,4-diphenylcyclopentadienyl)-6-tert-butylphenol ((DCBP)H₂, 8), 2-(3,4-diphenylcyclopentadienyl)-4, 6-di-tert-butylphenol

Full text of DOI:10.1021/om030240y

Organometallics 2003, 22, 3877-3883
3877
Syn th esis, Str u ctu r es, a n d Ca ta lytic P r op er ties of
Con str a in ed Geom etr y
Cyclop en ta d ien yl-p h en oxytita n iu m Dich lor id es
Yuetao Zhang,† J ianhui Wang,† Ying Mu,*,†,§ Zhan Shi,‡ Chunsheng Lu¨,†
Yanrong Zhang,† Lijun Qiao,† and Shouhua Feng‡
College of Chemistry, J ilin University, 119 J iefang Road,
Changchun 130023, People’s Republic of China, State Key Laboratory of Inorganic Synthesis
and Preparative Chemistry, College of Chemistry, J ilin University,
119 J iefang Road, Changchun 130023, People’s Republic of China, and Key Laboratory for
Supramolecular Structure and Materials of Ministry of Education, J ilin University,
Changchun 130023, People’s Republic of China
Received April 2, 2003
The synthesis of four new bidentate ligands, 2-(3,4-diphenylcyclopentadienyl)-6-phenylphen-
ol ((DCPP)H2, 7), 2-(3,4-diphenylcyclopentadienyl)-6-tert-butylphenol ((DCBP)H2, 8), 2-(3,4-
diphenylcyclopentadienyl)-4, 6-di-tert-butylphenol (DCDBP)H2, 9), and 2-(3,4-diphenylcy-
clopentadienyl)-6-methylphenol ((DCMP)H2, 10), as well as their corresponding constrained
geometry cyclopentadienyl-phenoxytitanium dichlorides ((DCPP)TiCl2 (11), (DCBP)TiCl2 (12),
(DCDBP)TiCl2 (13), and (DCMP)TiCl2 (14)), are described. Complexes 11-14 were synthe-
sized from the reaction of TiCl4 with the corresponding dilithio salt of the ligand. Molecular
structures of 11 and 12 were determined by single-crystal X-ray diffraction studies. The
Cp(cent)-Ti-O angles of 107.4° for 11 and 106.7° for 12 reveal their sterically open features
i
-
as catalyst precursors. When activated with Bu3Al and Ph3C+B(C6F5)4 , complexes 11-14
exhibit reasonable catalytic activity for ethylene polymerization, producing polyethylenes
with moderate molecular weights and melt transition temperatures. Compounds 12 and 13
show good catalytic activity for copolymerization of ethylene with 1-hexene.
In tr od u ction
hand, a considerable number of catalysts with a pendent
oxygen5 donor on the cyclopentadienyl ligand have also
been reported. Among them, the tetramethylcyclopen-
tadienyl-4-methylphenoxytitanium dibenzyl complex,
(TCP)Ti(CH2Ph)2 (2), is particularly interesting due to
its structural features and good catalytic activities.6
However, the synthesis of this type of catalyst was found
to be difficult. Marks et al. have tried various synthetic
strategies, and only the dibenzyl titanium complex 2
was obtained. Since then, there have been no further
reports on the synthesis and catalytic properties of this
Group 4 constrained geometry metallocene catalysts
have received extensive attention in recent years be-
cause of their importance in industrial applications.1 In
particular the constrained geometry catalysts with a
pendent nitrogen2 donor on the cyclopentadienyl ligand,
such as Me2Si(η5-Me4C5)(tBuN)MX2 (1, M ) Ti, Zr, Hf;
X ) Cl, Me, CH2Ph),3 have been widely studied in
industry as well as academic institutions.4 On the other
* To whom correspondence should be addressed. Fax: (+86)-431-
8949334. Tel: (+86)-431-8499136. E-mail: ymu@mail.jlu.edu.cn.
† College of Chemistry.
‡ State Key Laboratory of Inorganic Synthesis and Preparative
Chemistry.
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Bercaw, J . E. Synlett 1990, 2, 74-84. (c) Shapiro, P. J .; Bunel, E. E.;
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10.1021/om030240y CCC: $25.00 © 2003 American Chemical Society
Publication on Web 07/08/2003

3878 Organometallics, Vol. 22, No. 19, 2003
Sch em e 1. Syn th etic P r oced u r e of Liga n d s 7-10
Zhang et al.
n
type of catalyst until a very recent communication.7 We
have recently modified the ligand by introducing steri-
cally bulky substituents to the cyclopentadienyl and
phenoxy groups in order to prevent the formation of
multinuclear species and biscyclopentadienyl complexes.
With the modified ligands, a number of new Cp-phenoxy
titanium(IV) dichloride complexes have been synthe-
sized for the first time. We report here the convenient
preparation of 2-(3,4-diphenylcyclopentadienyl)-6-phen-
ylphenol ((DCPP)H2, 7), 2-(3,4-diphenylcyclopentadi-
enyl)-6-tert-butylphenol ((DCBP)H2, 8), 2-(3,4-diphenyl-
cyclopentadienyl)-4,6-di-tert-butylphenol ((DCDBP)H2,
9), and 2-(3,4-diphenylcyclopentadienyl)-6-methylphenol
((DCMP)H2, 10), and the synthesis and characterization
of the corresponding titanium(IV) dichloride complexes
((DCPP)TiCl2, 11), ((DCBP)TiCl2, 12), ((DCDBP)TiCl2,
13), and ((DCMP)TiCl2, 14), as well as their catalytic
performance in ethylene polymerization and copoly-
merization with 1-hexene.
2-bromo-6-methylphenol (6) with BuLi, with 3,4-diphen-
yl-2-cyclopentenone in toluene at room temperature
followed by heating the reaction mixture at 65 °C
produces 7-10 respectively (Scheme 1). We have tried
the reaction in different solvents and found that reac-
tions carried out in Et2O or THF gave no desired
product. In addition, 7-10 were obtained in higher
yields through the lithium hydroxide elimination route
by heating the reaction mixture directly. Reactions
carried out in a normal way with the dehydration step
with concentrated HCl give products in low yields.
Compounds 7-10 were found to be stable under inert
atmosphere. Decomposition occurred when they were
left in air for several hours with a gradual color change
from pale yellow to dark brown. The 2-bromophenols
3-6 were prepared from the reaction of Me2NBr with
the corresponding phenol in toluene at -15 °C. It is
necessary to keep the reaction at lower temperatures
in order to increase the selectivity and reduce the
multibromination byproducts. Compound 5 was ob-
tained in highest yield among 3-6 due to the existence
of the tert-butyl group at the para position of the
starting phenol. Compounds 3-10 were characterized
by elemental analysis and NMR spectroscopy.
Resu lts a n d Discu ssion
Design a n d Syn th esis of Liga n d s. Besides the
above-mentioned reason, the ligands were designed also
with following considerations: (1) The bulky substituent
at the ortho position of the phenol and the two phenyl
groups on the Cp ring construct a relatively crowded
environment around the Ti metal center, thus could
prevent the complex from dimerization through Cl and
O atoms, and coordination through the O atom to the
Al atom in methylaluminoxane (MAO) or trialkylalu-
minum. (2) The two electron-withdrawing Ph groups on
the Cp ring of the ligands would reduce the electron
density of the Cp- and its reactivity in the metalation
reaction, therefore increasing the selectivity of forming
the desired complexes in their synthetic reactions. The
ligands 7-10 were synthesized by a modified literature
procedure.6,8 The reaction of the dilithio salt of the
corresponding 2-bromophenol, which was obtained by
treating 2-bromo-6-phenylphenol (3), 2-bromo-6-tert-
butylphenol (4), 2-bromo-4,6-di-tert-butylphenol (5), or
Syn t h esis of Tit a n iu m (IV) Dich lor id e Com -
p lexes 11-14. Attempts to prepare the titanium(IV)
dichloride complexes through amine elimination,3a,9
alkane elimination,6,10 or Me3SiCl elimination11 ap-
proaches were unsuccessful. Complexes 11-14 were
finally synthesized in moderate yields by the traditional
reaction of TiCl4 with the dilithio salt of the correspond-
ing ligand 7-10 in toluene (Scheme 2). Considering the
fact that 2 could not be synthesized by lithium salt
(9) (a) Diamond, G. M.; Rodewald, S.; J ordan, R. F. Organometallics
1995, 14, 5-7. (b) Diamond, G. M.; J ordan, R. F.; Petersen, J . L. J .
Am. Chem. Soc. 1996, 118, 8024-8033. (c) Mu, Y.; Piers, W. E.;
MacDonald, M. A.; Zaworotko, M. J . Can. J . Chem. 1995, 73, 2233-
2238. (d) Mu, Y.; Piers, W. E.; MacGillivray, L. R.; Zaworotko, M. J .
Polyhedron 1995, 14, 1-10. (e) Baker, R. W.; Wallace, B. J . Chem.
Commun. 1999, 1405-1406.
(10) (a) Mu, Y.; Piers, W. E.; MacQuarrie, D. C.; Zaworotko, M. J .;
Young, V. G., J r. Organometallics 1996, 15, 2720-2726. (b) Mu, Y.;
Piers, W. E.; MacQuarrie, D. C.; Zaworotko, M. J . Can. J . Chem. 1996,
74, 1696-1703. (c) Chen, Y. X.; Marks, T. J . Organometallics 1997,
16, 3649-3657.
(11) (a) Ready, T. E.; Chien, J . C. W.; Rausch, M. D. J . Organomet.
Chem. 1996, 519, 21-28. (b) Cardoso, A. M.; Clark, R. J . H.; Moor-
house, S. J . Chem. Soc., Dalton Trans. 1980, 1156-1160. (c) Winter,
C. H.; Zhou, X.-X.; Dobbs, D. A.; Heeg, M. J . Organometallics 1991,
10, 210-214.
(7) Turner, L. E., Thorn, M. G., Fanwick, P. E., Pothwell, I. P. Chem.
Commun. 2003, 1034-1035.
(8) (a) Zhang, F.; Mu, Y.; Zhao, L. G..; Zhang, Y. T.; Bu, W. M.; Chen,
C. X.; Zhai, H. M.; Han, H.; J . Organomet. Chem. 2000, 613, 68-76.
(b) Zhang, F.; Mu, Y.; Wang, J . H.; Shi, Z.; Bu, W. M.; Zhang, Y. T.;
Feng, S. H. Polyhedron 2000, 19, 1941-1947.

Cyclopentadienyl-phenoxytitanium Dichlorides
Organometallics, Vol. 22, No. 19, 2003 3879
F igu r e 1. Structure of complex 11 (thermal ellipsoids are drawn at the 30% probability level).
Sch em e 2. Syn th etic P r oced u r e of Com p lexes 11-14
elimination reaction,6 the successful synthesis of 11-
14 indicates that our original consideration of the ligand
design is reasonable. The R group at the ortho position
of the phenolate and the two Ph groups on the Cp ring
indeed keep the monoligated titanium(IV) dichloride
complex from further reaction with the dilithio salt of
the ligand. The yield of the synthetic reaction could be
quite different depending on the nature of the R group.
The smallest methyl group results in the lowest yield
of 14 among these complexes, while the bulky tBu group
leads to higher yields of 12 and 13. The complexes 11-
14 were found to be considerably stable to air and
moisture and could be exposed to air for several days
without obvious decomposition. These complexes also
exhibit good thermostability. They could be heated to
200 °C without decomposition. The 1H and 13C NMR
spectra of 11-14 indicate that they all have Cs-sym-
metric structures in solution, and the two Ph groups
on the Cp ring are equivalent due to their free rotation
at room temperature.
Cr yst a l St r u ct u r es of 11 a n d 12. The molecular
structures of complexes 11 and 12 were determined by
X-ray crystal structure analyses. The ORTEP drawings
of the molecular structures are shown in Figure 1 and
Figure 2, respectively. The selected bond lengths and
angles are summarized in Table 1. There are two
independent molecules (11A and 11B) with minor
structural differences and a diethyl ether molecule in
the unit cell of 11. Selected bond lengths and angles for
11A will be used in subsequent discussions. The general
structural features of 11 and 12 are comparable to those
F igu r e 2. Structure of complex 12 (thermal ellipsoids are
drawn at the 30% probability level).
previously reported for 2. The geometry around tita-
mium in 11 or 12 can be described as pseudo-tetrahedral
with Cp(cent)-Ti-O angles of 107.4° for 11A and 106.7°
for 12, which are slightly smaller than the one in 2
(107.7°)6 and the Cp(cent)-Ti-N angle in 1 (107.6°),1a
indicating sterically open features for 11 and 12 similar
to complexes 1 and 2 as catalyst precursors. Both
molecules adopt Cs-symmetric structures. The Ti-Cring
(av) distances of 2.365 Å for 11A and 2.362 Å for 12 are
identical to that in 2 (2.36(1) Å) and slightly longer than
that in 1 (2.340 Å). The distances of Ti-C3 and Ti-C4
in both 11A and 12 are obviously longer than those of
the Ti-Cring bonds, and the Ti-Cp(cent)-C1 angles of
11A (86.6°) and 12 (86.9°) are less than 90°, which is
characteristic for constrained geometry metallocene
catalysts.1,3-6 The phenolate plane-Ph2Cp plane dihe-
dral angle is 89.7° for 11A and 86.5° for 12, and the

3880 Organometallics, Vol. 22, No. 19, 2003
Ta ble 1. Selected Bon d Len gth s a n d An gles
Zhang et al.
Complex 11A
Complex 11B
Complex 12
Ti(1)-O(1)
1.813(4)
2.323(6)
2.456(6)
2.255(2)
1.397(7)
1.495(8)
1.465(8)
104.15(15)
107.4
Ti(1)-C(1)
2.302(6)
Ti(1)-C(2)
Ti(1)-C(3)
2.409(6)
2.335(6)
2.237(2)
2.031
1.484(9)
103.88(15)
105.58(8)
86.6
Ti(1)-C(4)
Ti(1)-C(5)
Ti(1)-Cl(2)
Cp (cent)-Ti(1)
C(3)-C(12)
O(1)-Ti(1)-Cl(1)
Cl(1)-Ti(1)-Cl(2)
Ti(1)-Cp1(cent)-C(1)
C(1)-C(18)-C(19)
C(19)-O(1)-Ti(1)
Ti(1)-Cl(1)
O(1)-C(19)
C(1)-C(18)
C(4)-C(6)
O(1)-Ti(1)-Cl(2)
Cp1(cent)-Ti(1)-O(1)
C(18)-C(1)-Cp(cent)
C(18)-C(19)-O(1)
169.9
114.1(5)
112.9(5)
129.1(4)
Ti(2)-O(2)
1.821(4)
2.404(6)
2.336(6)
2.249(2)
1.388(7)
1.490(8)
1.465(8)
105.47(15)
107.3
Ti(2)-C(31)
2.325(6)
2.442(6)
2.309(6)
2.242(2)
2.033
1.495(8)
103.72(16)
104.66(9)
86.9
Ti(2)-C(32)
Ti(2)-C(33)
Ti(2)-C(34)
Ti(2)-C(30)
Ti(2)-Cl(3)
Ti(2)-Cl(4)
O(2)-C(48)
Cp2(cent)-Ti(2)
C(32)-C(41)
C(30)-C(47)
C(33)-C(35)
O(2)-Ti(2)-Cl(3)
Cl(3)-Ti(2)-Cl(4)
Ti(2)-Cp2(cent)-C(30)
C(30)-C(47)-C(48)
C(48)-O(2)-Ti(2)
O(2)-Ti(2)-Cl(4)
Cp2(cent)-Ti(2)-O(2)
C(47)-C(30)-Cp2(cent)
C(47)-C(48)-O(2)
169.2
114.9(6)
113.4(5)
128.3(4)
Ti(1)-O(1)
1.818(4)
2.315(7)
2.423(6)
2.228(2)
1.369(6)
1.481(9)
1.482(8)
103.60(17)
106.7
Ti(1)-C(1)
2.311(6)
2.440(7)
2.320(6)
2.247(2)
2.032
1.489(10)
103.56(14)
103.93(10)
86.9
Ti(1)-C(2)
Ti(1)-C(3)
Ti(1)-C(4)
Ti(1)-C(5)
Ti(1)-Cl(2)
Cp (cent)-Ti(1)
C(3)-C(16)
O(1)-Ti(1)-Cl(1)
Cl(1)-Ti(1)-Cl(2)
Ti(1)-Cp(cent)-C(1)
C(1)-C(6)-C(7)
C(7)-O(1)-Ti(1)
Ti(1)-Cl(1)
O(1)-C(7)
C(1)-C(6)
C(4)-C(22)
O(1)-Ti(1)-Cl(2)
Cp(cent)-Ti(1)-O(1)
C(6)-C(1)-Cp(cent)
C(6)-C(7)-O(1)
169.6
114.0(5)
112.7(5)
129.8(4)
Ta ble 2. Su m m a r y of Eth ylen e P olym er iza tion
Ca ta lyzed by Com p lexes 11-14 (a ctiva ted by
P h 3C+[B(C6F 5)4]-)a
(phenolate)C-C(ring) vector in both 11A and 12 is bent
9.4° from the Cp ring plane. The corresponding data for
2 are 81(1)° and 15(1)°, reflecting less steric strain in
11 and 12 than in 2. The Ti-O bond lengths of 1.813(4)
Å in 11A and 1.818(4) Å in 12 are shorter than that in
2 (1.851(7) Å), and the Ti-O-C angles of 129.1(4)° in
11A and 129.8(4)° in 12 are larger than that in 2 (126.6-
(6)°), indicating more Ti-O double-bond character in 11
and 12.4f,12
Eth ylen e P olym er iza tion Stu d ies. Complexes 11-
14 were studied as ethylene polymerization catalysts,
and the results are summarized in Table 2. Upon
activation with Al(iBu)3 and Ph3C+B(C6F5)4-, complexes
11-14 all show good catalytic activity for ethylene
polymerization, producing polyethylenes with moderate
molecular weights and melt transition temperatures.
The order of the catalytic activity for ethylene poly-
merization under similar conditions (see runs 2, 7, 12,
and 15 in Table 2) is 13 > 12 > 11 ≈ 14, which could
obviously be attributed to the nature of the substituents
on the phenolate. By examining the structure of these
catalysts, it can be clearly seen that the electronic effect
of the R1 group at the para position of the phenolate
plays a significant role in the catalytic activity when
the R group at the ortho position is kept the same
(comparing 12 and 13), while both steric and electronic
effects of the R group at the ortho position seem to be
T
yield
(g)
Mηc ×
Tm
no. catalyst Al:Ti (°C)
activityb
10-4
(°C)d
1
2
3
4
5
6
7
8
11
11
11
11
11
12
12
12
12
12
13
13
13
14
14
14
20
40
60
40
40
20
40
60
40
40
20
40
60
20
40
60
80
80
80
100
60
80
80
80
100
60
80
80
80
80
80
80
0.43
0.54
0.32
0.15
0.31
1.43
1.98
1.31
0.92
1.09
2.25
3.17
1.91
0.46
0.58
0.39
433
544
322
151
312
1380
1910
1270
889
1050
2430
3420
2060
406
11
20
18
13
127.4
132.6
130.7
128.1
127.1
122.3
125.4
127.4
124.2
124.3
121.7
123.2
121.1
120.9
122.5
122.1
14
4.5
4.3
8.9
7.1
4.4
2.9
3.8
4.2
10
9
10
11
12
13
14
15
16
512
344
9.2
9.7
a
Polymerization conditions: solvent 50 mL of toluene, catalyst
b
1 mg, B/Ti ratio 1.5, time 30 min, ethylene pressure 5 bar. kg
PE (mol Ti)-1 h-1
.
c Measured in decahydronaphthalene at 135 °C.
Determined by DSC at a heating rate of 10 °C min-1
.
d
important in determining the order of the catalytic
activity when the R1 group at the para position is
unchanged (comparing 11, 12, and 14).13 For all com-
plexes, the catalytic activity increases with the increase
in Al/Ti ratio and reaches the highest catalytic activities
with the Al/Ti ratio of 40. Further increasing the Al/Ti
ratio results in a decrease in the catalytic activity. It is
(12) (a) Huffman, J . C.; Moloy, K. G.; Marsella, J . A.; Caulton, K.
G. J . Am. Chem. Soc. 1980, 102, 3009-3014. (b) Cetinkaya, B.;
Hitchcock, P. B.; Lappert, M. F.; Torroni, S.; Atwood, J . L.; Hunter,
W. E.; Zaworotko, M. J . J . Organomet. Chem. 1980, 188, C31-C 35.
(c) Fandos, R.; Meetsma, A.; Teuben, J . H. Organometallics 1991, 10,
59-60.
(13) Mo¨hring, P. C.; Coville, N. J . J . Organomet. Chem. 1994, 479,
1-29.

Cyclopentadienyl-phenoxytitanium Dichlorides
Organometallics, Vol. 22, No. 19, 2003 3881
Ta ble 3. Cop olym er iza tion of Eth ylen e w ith
1-Hexen e Ca ta lyzed by Com p lexes 12 a n d 13
modified ligands 7-10 from the reaction of the dilithio
salt of the corresponding ligand with TiCl4. Compounds
11-14 are considerably stable to air and moisture and
can be exposed to air for several days without obvious
decomposition. They also have good thermostability and
can be heated to 200 °C without decomposition. 1H and
13C NMR spectra and X-ray crystallography indicate
that 11-14 have Cs-symmetric structures. The Cp-
(cent)-Ti-O angle is about 107° for these complexes,
which is characteristic of constrained geometry metal-
locene catalysts. Upon activation with Al(iBu)3 and
Ph3C+B(C6F5)4-, 11-14 exhibit reasonable catalytic
activity for ethylene polymerization. The catalytic activ-
ity of 11-14 is obviously relative to the nature of the
substituents at the phenoxy group, and the order of the
catalytic activity under similar conditions is 13 > 12 >
11 ≈ 14. Compounds 12 and 13 show good catalytic
activity for copolymerization of ethylene with 1-hexene.
-
a
(a ctiva ted by P h 3C+B(C6F 5)4
)
run
1-hexene yield
no. catalyst (mol/L)
Mηc × Tm 1-hexene
(g) activityb 10-3 (°C)d contente
1
2
3
4
5
6
7
8
12
12
12
12
13
13
13
13
0.40
0.24
0.16
0.08
0.40
0.24
0.16
0.08
3.11
3.78
2.42
2.09
3.85
4.60
3.32
2.87
3010
3650
2340
2020
4150
4960
3580
3090
5.2
6.1
5.9
13.0
4.1
5.5
41.4
76.1
76.1
94.9
40.8
86.2
91.6
0.152
0.130
0.098
0.058
0.151
0.090
0.075
0.051
7.6
9.0 104.5
a
Polymerization conditions: solvent 50 mL of toluene, temper-
ature 80 °C, catalyst 1 mg, B/Ti ratio 1.5, Al/Ti ratio 40, time 30
b
min, ethylene pressure 5 bar. kg polymer (mol Ti)-1 h-1
.
c Mea-
d
sured in xylene at 105 °C. Determined by DSC at a heating rate
of 10 °C min-1 e Calculated by 13C NMR spectra.
.
possible that excessive Al(iBu)3 would consume so much
Ph3C+B(C6F5)4- that the catalyst could not be efficiently
activated.14 The catalytic activity of all complexes is low
at room temperature and increases at elevated temper-
atures, which reflects the nature of tight interaction
between the catalyst cation and the cocatalyst anion in
the constrained geometry catalyst systems.10c It is also
worth noting that the lower activity catalysts 11 and
14 give higher viscosity-average molecular weights. One
possible explanation for this result is that both the chain
propagation and chain termination steps are slow with
these catalysts. The slow propagation will ensure having
sufficient monomer to coordinate to the catalyst metal
center and thus further suppress the chain termination
through â-H elimination. 13C NMR analysis of typical
polymer samples reveals that the polyethylenes contain
mainly ethyl branches together with a small amount of
long-chain branches.15 The degree of ethyl branching is
2-4 branches per 1000 C atoms for samples obtained
with 11, 12, and 13 and 4-6 branches per 1000 C atoms
for samples obtained with 14. The difference in degree
of branching might be responsible for the different melt
transitions for samples obtained with 11 and 14.
Cop olym er iza tion of Eth ylen e w ith 1-Hexen e.
Complexes 12 and 13 were also briefly tested for
copolymerization of ethylene and 1-hexene, and the
results were summarized in Table 3. By comparison
with the ethylene homopolymerization results listed in
Table 2, a positive comonomer effect on the catalytic
activity under our conditions can be obviously seen for
the copolymerization systems. 13C NMR analysis16 of
copolymers indicates pretty good incorporation of 1-hex-
ene into the polymer chain for both catalyst systems,
although the feed concentration of 1-hexene is quite low
for all experiments. Detailed investigations on the
copolymerization and the extension of the catalyst
family are currently underway.
Exp er im en ta l Section
Gen er a l Com m en ts. Reactions with organometallic re-
agents were carried out under a nitrogen atmosphere (ultra-
high purity) using standard Schlenk techniques.17 Solvents
were dried and distilled prior to use.18 Polymerization grade
ethylene was further purified by passage through columns of
10 Å molecular sieves and MnO. Al(iBu)3, nBuLi, and TiCl4
were purchased from Aldrich. 3,4-Diphenyl-2-cyclopentenone19
and Ph3C+B(C6F5)4
were prepared according to literature
-
20
procedures. NMR spectra were measured using a Varian
Unity-400 or Varian Mercury-300 NMR spectrometer. 13C
NMR spectra for polymers were recorded at 130 °C. The pulse
delay was 8 s. The acquisition time was 1 s. The pulse angle
was 90°. The polymer solutions were prepared by dissolving
polymers in a mixed solution of 1,2,4-trichlorobenzene/benzene-
d6 (90/10 wt %).
P r ep a r a tion of 2-Br om o-6-p h en ylp h en ol (3). Br2 (5.9
mL, 0.115 mol) was added dropwise to a solution of Me2NH
(0.12 mol) and NaOH (0.23 mol) in 50 mL of H2O at -15 °C.
The mixture was stirred for 30 min at this temperature and
extracted with toluene (100 mL). The organic layer was
separated and dried with MgSO4 to give a yellow solution of
Me2NBr, which was added to a solution of 2-phenylphenol (16.5
g, 0.097mol) in 100 mL of toluene at -15 °C. The mixture was
stirred for 4 h, slowly warmed to room temperature, and
stirred overnight, then acidified with 20 mL of HCl (6 M). The
organic layer was separated and dried with MgSO4. Pure
product (16.9 g, 70.0%) was obtained by column chromatog-
raphy over silica (hexanes/CH2Cl2, 2:1) as pale purple needles.
Anal. Calcd for C12H9BrO (249.10): C, 57.86; H, 3.64. Found:
C, 57.83; H, 3.66. 1H NMR (CDCl3, 300 MHz; 298 K): δ 7.369-
7.600 (m, 6H, Ph), 7.240 (d, 1H, Ph), 6. 871 (t, 1H, Ph), 5.680
(s, 1H, OH).
P r ep a r a tion of 2-Br om o-6-ter t-bu tylp h en ol (4). Com-
pound 4 was prepared in the same manner as 3 with 2-tert-
butylphenol (20 mL, 0.13 mol) as starting material. Pure
product (23.9 g, 80.1%) was obtained by distillation under
reduced pressure at 89-90 °C/10 mmHg as light yellow oils.
Anal. Calcd for C10H13BrO (229.11): C, 52.42; H, 5.72. Found:
1
C, 52.39; H, 5.68. H NMR (CDCl3, 300 MHz; 298 K): δ 7.326
Con clu sion s
(d, 1H, Ph), 7.210 (d, 1H, Ph), 6.729 (t, 1H, Ph), 5.798 (s, 1H,
OH), 1.395 (s, 9H, Ph-tBu).
The constrained geometry cyclopentadienyl-phenoxy-
titanium dichlorides 11-14 can be synthesized with
P r ep a r a tion of 2-Br om o-4,6-Di-ter t-bu tylp h en ol (5).
Compound 5 was prepared in the same manner as 3 with 2,4-
(14) Bochmann, M.; Sarsfield, M. J . Organometallics 1998, 17,
5908-5912.
(15) Kooko, E.; Lehmus, P.; Leino, R.; Luttikhedde, H. J . G.; ekholm,
P. Na¨sman, J . H.; Seppa¨la¨, J . V. Macromolecules 2000, 33, 9200-9204.
(16) Hsieh, E. T.; Randall, J . C. Macromolecules 1982, 15, 1402-
1406.
(17) Shriver, D. F. The Manipulation of Air-Sensitive Compounds;
McGraw-Hill: New York, 1969.
(18) Perrin, D. D.; Armarego, W. L. F.; Perrin, D. R. The Purification
of Laboratory Chemicals; Pergamon: New York, 1980.
(19) Geissmann, T. A.; Koelsch, C. F. J . Org. Chem. 1939, 3, 489-
502.

3882 Organometallics, Vol. 22, No. 19, 2003
Zhang et al.
di-tert-butylphenol (22 g, 0.107mol) as starting material. Pure
product (25.9 g, 85.2%) was obtained by column chromatog-
raphy over silica (hexanes) as yellow crystals. Anal. Calcd for
3.978 (s, 2H, Cp), 2.309 (s, 3H, Ph-Me). 13C NMR (CDCl3, 75.4
MHz; 298 K): δ 151.364, 142.409, 141.848, 139.917, 137.089,
136.830, 134.560, 129.935, 128.760, 128.645, 128.588, 128.550,
128.069, 127.474, 126.902, 126.295, 124.440, 120.529, 48.054,
16.388 ppm.
C
14H21BrO (285.22): C, 58.95; H, 7.42. Found: C, 58.97; H,
1
7.39. H NMR (CDCl3, 300 MHz; 298 K): δ 7.316 (s, 1H, Ph),
7.236 (s, 1H, Ph), 5.651 (s, 1H, OH), 1.397 (s, 9H, Ph-tBu), 1.280
(s, 9H, Ph-tBu).
P r ep a r a t ion of [η5;η1-(3,4-P h 2C5H 2)-6-p h en yl-C6H 3O]-
TiCl2(11). A solution of nBuLi (5.2 mmol) was added dropwise
to a solution of 2-(3,4-diphenylcyclopentadienyl)-6-phenylphen-
ol (1.0 g, 2.6 mmol) in Et2O (100 mL) at -78 °C. The reaction
mixture was allowed to warm to room temperature and stirred
overnight. Solvent was removed in vacuo, and the residue was
washed with hexane and then dissolved in toluene (150 mL).
A solution of TiCl4 (2.6 mmol) in toluene (50 mL) was slowly
added at -78 °C, and the reaction mixture was stirred at room
temperature overnight. The precipitate was filtered off, and
the solvent was removed to leave a red solid. Recrystallization
from CH2Cl2/hexane (1:3) gave pure 11 as red crystals (0.56
g, 39.9%), mp 146-148 °C. Anal. Calcd for C29H20Cl2OTi‚
0.5C4H10O (540.34): C, 68.91; H, 4.66. Found: C, 67.80; H,
P r ep a r a tion of 2-Br om o-6-m eth ylp h en ol (6). Compound
6 was prepared in the same manner as 3 with 2-methylphenol
(18 g, 0.166 mol) as starting material. Pure product (23.9 g,
76.8%) was obtained by distillation under reduced pressure
at 82-83 °C/10 mmHg as brown oils. Anal. Calcd for C7H7-
1
BrO (187.03): C, 44.95; H, 3.77. Found: C, 44.91; H, 3.80. H
NMR (CDCl3, 300 MHz; 298 K): δ 7.277 (d, 1H, Ph), 7.048 (d,
1H, Ph), 6.693 (t, 1H, Ph), 5.557 (s, 1H, OH), 2.285 (s, 3H,
Ph-Me).
P r ep a r a tion of 2-(3,4-Dip h en ylcyclop en ta d ien yl)-6-
p h en ylp h en ol (7). A solution of 2-bromo-6-phenylphenol (3.0
g, 12.0 mmol) in Et2O (40 mL) was added dropwise to a
n
solution of BuLi (25 mmol) in Et2O (20 mL) at -15 °C. The
1
4.59. H NMR (300 MHz, CDCl3, 298 K): δ 7.214 (s, 2H, Cp),
mixture was slowly warmed to room temperature and stirred
overnight. The solvent was removed in vacuo, and the residue
was dissolved in toluene (60 mL). The solution was cooled to
-15 °C, and a solution of 3,4-diphenyl-2-cyclopentenone (2.8
g, 12.0 mmol) in toluene (40 mL) was added dropwise over an
hour. The reaction mixture was stirred overnight and then
heated for another 4 h at 65 °C and quenched with 20 mL of
saturated NH4Cl(aq). The organic layer was separated, dried
over MgSO4, filtered, and concentrated by distillation under
reduced pressure. Pure product (1.8 g, 38.8%) was obtained
by column chromatography over silica (hexanes/CH2Cl2, 1:2)
as yellow needles. Anal. Calcd for C29H22O (386.47): C, 90.12;
H, 5.74. Found: C, 90.08; H, 5.71. 1H NMR (CDCl3, 300 MHz;
298 K): δ 6.979-7.519 (m, 19H, Cp, Ph), 5.775 (s, 1H, OH),
4.072 (s, 2H, Cp). 13C NMR (CDCl3, 75.4 MHz; 298 K): δ
149.761, 142.088, 141.607, 139.169, 137.177, 136.910, 136.807,
135.769, 129.382, 129.317, 128.905, 128.646, 128.420, 128.230,
128.088, 127.791, 127.516, 127.039, 126.444, 123.124, 120.552,
47.230 ppm.
7.164-7.929 (m, 18H, Ph), 3.478 (q, 2H, CH2 of Et2O), 1.208
(t, 3H, CH3 of Et2O). 13C NMR (75.4 MHz, CDCl3, 298 K): δ
171.629, 144.793, 136.090, 133.548, 132.320, 131.362, 130.439,
130.274, 129.702, 129.301, 129.000, 128.462, 128.336, 127.584,
127.134, 126.260, 124.528, 65.870, 15.282 ppm.
P r ep a r a tion of [η5;η1-(3,4-P h 2C5H2)-6-ter t-bu tyl-C6H3O]-
TiCl2 (12). Reaction of the dilithio salt of 8 (2.0 mmol) with
TiCl4 (2.0 mmol) in toluene (80 mL) was carried out in the
same way as described above for the synthesis of 11. Pure 12
(0.46 g, 47.6%) was obtained as red crystals, mp 128-130 °C.
Anal. Calcd for C27H24Cl2OTi (483.25): C, 67.11; H, 5.01.
1
Found: C, 67.05; H, 4.96. H NMR (CDCl3, 400 MHz; 298 K):
δ 7.165 (s, 2H, Cp), 7.107-7.581 (m, 13H, Ph), 1.366 (s, 9H,
Ph-tBu). 13C NMR (CDCl3, 100.5 MHz; 298 K): δ 173.748,
145.163, 135.786, 133.366, 132.478, 131.469, 130.445, 129.725,
129.209, 128.321, 126.956, 126.000, 124.050, 34.957, 29.624
ppm.
1
5
P r ep a r a t ion of [η ;η -(3,4-P h 2C5H 2)-4,6-d i-ter t-b u t yl-
P r ep a r a tion of 2-(3,4-Dip h en ylcyclop en ta d ien yl)-6-
ter t-bu tylp h en ol (8). Compound 8 was prepared in the same
manner as 7 with 2-bromo-6-tert-butylphenol (4.35 g, 19 mmol)
as starting material. Pure product (3.4 g, 48.8%) was obtained
as pale yellow crystals. Anal. Calcd for C27H26O (366.48): C,
88.48; H, 7.15. Found: C, 88.40; H, 7.18. 1H NMR (CDCl3, 300
MHz; 298 K): δ 6.894-7.379 (m, 13H, Ph), 6.990 (s, 1H, Cp),
C6H2O]TiCl2 (13). Reaction of the dilithio salt of 9 (1.8 mmol)
with TiCl4 (1.8 mmol) in toluene (80 mL) was carried out in
the same way as described above for the synthesis of 11. Pure
13 (0.55 g, 56.6%) was obtained as red crystals, mp 135-137
°C. Anal. Calcd for C31H32Cl2OTi (539.36): C, 69.03; H, 5.98.
1
Found: C, 68.95; H, 5.94. H NMR (CDCl3, 400 MHz; 298 K):
6.056 (s, 1H, OH), 3.941 (s, 2H, Cp), 1.447 (s, 9H, Ph-tBu). 13
C
δ 7.330-7.572 (m, 12H, Ph), 7.179 (s, 2H, Cp), 1.366 (s, 18H,
Ph-tBu). 13C NMR (CDCl3, 100.5 MHz; 298 K): δ 171.517,
147.340, 145.512, 134.595, 133.252, 132.622, 131.538, 130.142,
129.732, 129.125, 128.306, 123.807, 122.882, 35.139, 34.881,
31.665, 29.722 ppm.
NMR (CDCl3, 75.4 MHz; 298 K): δ 151.521, 142.390, 141.249,
140.218, 136.586, 136.395, 136.338, 134.148, 128.562, 128.390,
128.363, 127.844, 127.337, 126.814, 126.406, 126.146, 123.605,
119.850, 48.585, 34.894, 29.617 ppm.
1
P r ep a r a tion of 2-(3,4-Dip h en ylcyclop en ta d ien yl)-4,6-
d i-ter t-bu tylp h en ol (9). Compound 9 was prepared in the
same manner as 7 with 2-bromo-4,6-di-tert-butylphenol (4.28
g, 15 mmol) as starting material. Pure product (3.53 g, 55.7%)
5
P r ep a r a tion of [η ;η -(3,4-P h 2C5H2)-6-m eth yl-C6H3O]-
TiCl2 (14). Reaction of the dilithio salt of 10 (2.2 mmol) with
TiCl4 (2.2 mmol) in toluene (100 mL) was carried out in the
same way as described above for the synthesis of 11. Pure 14
(0.33 g, 34.0%) was obtained as red crystals, mp 207-209 °C.
Anal. Calcd for C24H18Cl2OTi (441.17): C, 65.34; H, 4.11.
was obtained as yellow crystals. Anal. Calcd for C31H34
O
(422.60): C, 88.10; H,8.11. Found: C, 88.06; H, 8.13. 1H NMR
(CDCl3, 400 MHz; 298 K): δ 7.159-7.394 (m, 12H, Ph), 6.961
(s, 1H, Cp), 5.909 (s, 1H, OH), 3.957 (s, 2H, Cp), 1.453 (s, 9H,
Ph-tBu), 1.333 (s, 9H, Ph-tBu). 13C NMR (CDCl3, 75.4 MHz;
298 K): δ 149.124, 142.939, 141.924, 141.203, 140.108, 136.601,
136.456, 135.499, 134.102, 128.543, 128.386, 128.344, 127.860,
127.291, 126.761, 123.483, 123.021, 122.834, 48.661, 35.119,
34.322, 31.598, 29.682 ppm.
1
Found: C, 65.11; H, 4.02. H NMR (CDCl3, 300 MHz; 298 K):
δ 7.085-7.568 (m, 13H, Ph), 7.163 (s, 2H, Cp), 2.174 (s, 3H,
Ph-Me). 13C NMR (CDCl3, 75.4 MHz; 298 K): δ 173.560,
153.646, 145.614, 133.606, 132.633, 131.763, 129.950, 129.492,
128.565, 128.069, 125.776, 124.269, 123.326, 15.511 ppm.
X-r a y Str u ctu r e Deter m in a tion s of 11 a n d 12. Single
crystals of 11 and 12 suitable for X-ray structural analysis
were obtained from the mixture of CH2Cl2/hexane (v/v ) 1:3).
The data were collected at 293 K on the Siemens P4 four-circle
diffractometer for 11 and a Bruker SMART-CCD diffractome-
ter for 12 (graphite-monochromated Mo KR radiation: λ )
0.71073 Å). Details of the crystal data, data collections, and
structure refinements are summarized in Table 4. Both
P r ep a r a tion of 2-(3,4-Dip h en ylcyclop en ta d ien yl)-6-
m eth ylp h en ol (10). Compound 10 was prepared in the same
manner as 7 with 2-bromo-6-methylphenol (3.42 g, 18.3 mmol)
as starting material. Pure product (2.09 g, 35.2%) was obtained
as yellow crystals. Anal. Calcd for C24H20O (324.41): C, 88.85;
H, 6.21. Found: C, 88.80; H, 6.18. 1H NMR (CDCl3, 300 MHz;
298 K): δ 6.841-7.409 (m, 14H, Ph, Cp), 5.529 (s, 1H, OH),

Cyclopentadienyl-phenoxytitanium Dichlorides
Organometallics, Vol. 22, No. 19, 2003 3883
Ta ble 4. Cr ysta l Da ta a n d Str u ctu r a l Refin em en t
Deta ils for 11 a n d 12
desired temperature, and saturated with ethylene (1.0 bar).
The polymerization reaction was started by injection of a
mixture of catalyst and Al(iBu)3 in toluene (5 mL) and a
solution of Ph3C+B(C6F5)4- in toluene (5 mL) at the same time.
The vessel was repressurized to needed pressure with ethylene
immediately, and the pressure was maintained by continu-
ously feeding monomer. After 30 min, the polymerization was
quenched by injecting acidified methanol [HCl (3 M)/methanol
) 1:1]. The mixture was stirred overnight, and the polymer
was collected by filtration, washed with water and methanol,
and dried in vacuo. For copolymerization experiments, ap-
propriate amounts of 1-hexene were added into the system.
11
12
mol formula
mol wt
cryst system
space group
a/Å
C
31H25Cl2O1.5Ti
C27H24Cl2OTi
483.26
triclinic
P1h
10.458(3)
11.337(3)
13.409(4)
66.697(17)
86.48(2)
73.363(17)
1396.6(7)
2
540.31
triclinic
P1h
11.791(4)
14.111(4)
18.567(6)
78.38(2)
73.45(2)
66.05(2)
2693.4(13)
4
b/Å
c/Å
R/deg
â/deg
γ/deg
V/Å3
Ack n ow led gm en t. This work was supported by the
National Natural Science Foundation of China (Nos.
29734143 and 29672013).
Z
Dc/g cm-3
F(000)
1.332
1116
1.149
500
abs coeff/mm-1
scan type
collect range, deg
no. of reflns
no. of indep reflns
Rint
0.540
ω-2θ
0.512
ω-2θ
Note Ad d ed a fter ASAP . This paper was removed
from the Web on J uly 29, 2003, and reinstated on the
Web Aug 12, 2003. The order of author names is now
changed.
3.74 e 2θ e 49.98 7.04 e 2θ e 46.44
11 281
9437
0.0278
2864
2864
0.000
no. of data/restraints/ 9437/7/617
params
2864/0/280
Su p p or tin g In for m a tion Ava ila ble: Tables of crystal
data and structure refinement, atomic positional parameters,
bond lengths and angles, anisotropic temperature factors, and
R
Rw
0.0697
0.1953
0.970
0.0733
0.2545
1.135
1.360
-0.308
1
calculated hydrogen atom positions for 11 and 12 and H and
goodness of fit
largest diff peak
and hole/e Å-3
13C NMR spectra for 7-14. This material is available free of
1.442
-0.312
charge via the Internet at http://pubs.acs.org.
OM030240Y
structures were solved by direct methods21 and refined by full-
matrix least-squares on F2. All non-hydrogen atoms were
refined anisotropically, and the hydrogen atoms were included
in idealized positions. All calculations were performed using
the SHELXTL22 crystallographic software packages.
(20) (a) Massey, A. G.; Park, A. J . J . Org. Chem. 1962, 2, 245-250.
(b) Massey, A. G.; Park, A. J . J . Organomet. Chem. 1966, 5, 218-225.
(c) Chien, J . C. W.; Tsai, W. M.; Rasch, M. D. J . Am. Chem. Soc. 1991,
113, 8570-8571.
(21) SHELXTL; PC Siemens Analytical X-ray Instruments: Madi-
son WI, 1993.
P olym er iza tion Rea ction s. A dry 250 mL steel autoclave
was charged with 40 mL of toluene, thermostated at the
(22) Sheldrick, G. M. SHELXTL Structure Determination Programs,
Version 5.0; PC Siemens Analytical Systems: Madison, WI, 1994.