A family of zirconium complexes having two phenoxy - imine chelate ligands for olefin polymerization

Article abstract of DOI:10.1021/ja0032780

A zirconium complex having two phenoxy - imine chelate ligands, bis[N-(3-tert-butylsalicylidene)-anilinato]zirconium(IV)dichloride (1), was found to display a very high ethylene polymerization activity of 550 kg of polymer/mmol of cat·h with a viscosity average molecular weight, (M_v) value of 0.9 × 10⁴ at 25 °C at atmospheric pressure using methylalumoxane (MAO) as a cocatalyst. This activity is 1 order of magnitude larger than that exhibited by Cp₂ZrCl₂ under the same polymerization conditions. The use of Ph₃CB(C₆F₅)₄/i-Bu₃Al in place of MAO as a cocatalyst resulted in extremely high molecular weight polyethylene, M_v 505 × 10⁴, with an activity of 11 kg of polymer/mmol of cat·h at 50 °C. This M_v value is one of the highest values displayed by homogeneous olefin polymerization catalysts. Complex 1, using Ph₃CB(C₆F₅)₄/i-BU₃Al as a cocatalyst, provided a high molecular weight ethylene-propylene copolymer, M_v 109 × 10₄, with 8 kg of polymer/mmol of cat·h activity at a propylene content of 20.7 mol %. X-ray analysis revealed that complex 1 adopts a distorted octahedral coordination structure around the zirconium metal and that two oxygen atoms are situated in trans position while two nitrogen atoms and two chlorine atoms are situated in cis position. DFT calculations suggest that the active species derived from complex 1 possesses two available cis-located sites for efficient ethylene polymerization. Changing the tert-butyl group in the phenoxy benzene ring enhanced the polymerization activity. Bis[N-(3-cumyl-5-methylsalicylidene)cyclohexylaminato]zirconium(IV)dichloride (7) with MAO displayed an ethylene polymerization activity of 4315 kg of polymer/mmol of cat·h at 25 °C at atmospheric pressure. This activity corresponds to a catalyst turnover frequency (TOF) value of 42 900/s· atm. This TOF value is one of the largest not only for olefin polymerization but also for any known catalytic reaction. Ligands with additional steric congestion near the polymerization reaction center gave increased M_v values. The maximum M_v value, 220 × 10⁴ using MAO, was obtained with bis[N-(3,5-dicumylsalicylidene)-2′-isopropylanilinato]zirconium (IV)dichloride (15). Thus, polyethylenes ranging from low to exceptionally high molecular weights can be obtained from these zirconium complexes by changing the ligand structure and the choice of cocatalyst.

Full text of DOI:10.1021/ja0032780

J. Am. Chem. Soc. 2001, 123, 6847-6856
6847
A Family of Zirconium Complexes Having Two Phenoxy-Imine
Chelate Ligands for Olefin Polymerization
Shigekazu Matsui, Makoto Mitani, Junji Saito, Yasushi Tohi, Haruyuki Makio,
Naoto Matsukawa, Yukihiro Takagi, Kazutaka Tsuru, Masatoshi Nitabaru,
Takashi Nakano, Hidetsugu Tanaka, Norio Kashiwa, and Terunori Fujita*
Contribution from the R & D Center, Mitsui Chemicals, Inc., 580-32 Nagaura, Sodegaura,
Chiba, 299-0265, Japan
ReceiVed September 5, 2000
Abstract: A zirconium complex having two phenoxy-imine chelate ligands, bis[N-(3-tert-butylsalicylidene)-
anilinato]zirconium(IV)dichloride (1), was found to display a very high ethylene polymerization activity of
550 kg of polymer/mmol of cat‚h with a viscosity average molecular weight (Mv) value of 0.9 × 104 at 25 °C
at atmospheric pressure using methylalumoxane (MAO) as a cocatalyst. This activity is 1 order of magnitude
larger than that exhibited by Cp2ZrCl2 under the same polymerization conditions. The use of Ph3CB(C6F5)4/
i-Bu3Al in place of MAO as a cocatalyst resulted in extremely high molecular weight polyethylene, Mv 505
× 104, with an activity of 11 kg of polymer/mmol of cat‚h at 50 °C. This Mv value is one of the highest values
displayed by homogeneous olefin polymerization catalysts. Complex 1, using Ph3CB(C6F5)4/i-Bu3Al as a
cocatalyst, provided a high molecular weight ethylene-propylene copolymer, Mv 109 × 104, with 8 kg of
polymer/mmol of cat‚h activity at a propylene content of 20.7 mol %. X-ray analysis revealed that complex
1 adopts a distorted octahedral coordination structure around the zirconium metal and that two oxygen atoms
are situated in trans position while two nitrogen atoms and two chlorine atoms are situated in cis position.
DFT calculations suggest that the active species derived from complex 1 possesses two available cis-located
sites for efficient ethylene polymerization. Changing the tert-butyl group in the phenoxy benzene ring enhanced
the polymerization activity. Bis[N-(3-cumyl-5-methylsalicylidene)cyclohexylaminato]zirconium(IV)dichloride
(7) with MAO displayed an ethylene polymerization activity of 4315 kg of polymer/mmol of cat‚h at 25 °C
at atmospheric pressure. This activity corresponds to a catalyst turnover frequency (TOF) value of 42 900/s‚
atm. This TOF value is one of the largest not only for olefin polymerization but also for any known catalytic
reaction. Ligands with additional steric congestion near the polymerization reaction center gave increased Mv
values. The maximum Mv value, 220 × 104 using MAO, was obtained with bis[N-(3,5-dicumylsalicylidene)-
2′-isopropylanilinato]zirconium(IV)dichloride (15). Thus, polyethylenes ranging from low to exceptionally
high molecular weights can be obtained from these zirconium complexes by changing the ligand structure and
the choice of cocatalyst.
Introduction
complexes with diimine ligands,14 iron or cobalt complexes with
diimine-pyridine ligands,15 nickel complexes with phenoxy-
imine ligands,16 titanium complexes with diamide ligands,17,18
titanium complexes with two phosphineimide ligands,20 and
tantalum complexes with two amide-pyridine ligands.21 Many
Research and development of high-performance olefin po-
lymerization catalysts has contributed significantly to the
advancement of organometallic chemistry and polymer chem-
istry and has made a dramatic impact on the polyolefin industry.
More than 40 million tons of polyolefins are produced every
year using catalytic olefin polymerization. Historically, the
discovery of highly active catalysts results in the commercializa-
tion of new polyolefins. A recent example is the discovery of
group 4 metallocene catalysts, which display very high ethylene
polymerization activity.1-3 These high-performance olefin po-
lymerization catalysts have made possible the industrial produc-
tion of linear low-density polyethylene, isotactic and syndiotactic
polypropylene, syndiotactic polystyrene, etc.
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catalysts have been developed from nickel or palladium
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10.1021/ja0032780 CCC: $20.00 © 2001 American Chemical Society
Published on Web 06/22/2001

6848 J. Am. Chem. Soc., Vol. 123, No. 28, 2001
Matsui et al.
Table 1. Ethylene Polymerization with 1 or Cp2ZrCl2 Using MAO as a Cocatalysta
complex
(µmol)
MAO
(mmol)
yield
(g)
Mν
vinyl end groups
/1000 carbons
entry
Al/Zr
acitivetyb
× 10-4
Mw/Mn
1
2
3
4
5
6
7
1 (0.2)
1 (0.02)
1 (0.02)
1 (0.02)
1 (0.01)
Cp2ZrCl2 (0.5)
Cp2ZrCl2 (0.2)
1.25
1.25
2.50
6.25
1.25
1.25
1.25
6250
62500
125000
312500
125000
2500
3.29
0.92
0.89
0.82
0.42
1.13
0.46
197c
550
536
494
508
27
0.8
0.9
0.7
0.7
0.6
104
100
2.21
2.06
2.01
2.05
2.05
2.61
2.31
2.38
2.38
2.36
2.41
2.36
0.03
0.03
6250
28
a Conditions: 0.1 MPa ethylene pressure, 25 °C; solvent, toluene 250 mL; polymerization time, 5 min. b Activity, kg of polymer/mmol of cat‚h.
c Stirring difficulty was encountered because of excessive polymer production.
Scheme 1
of them display activities comparable to those of the metallocene
catalysts15,16,20 and, in some cases, behave as living polymeri-
zation catalysts of R-olefins.14c,17b,19i Others are capable of
producing functionalized polyolefins via coordination polym-
erization of ethylene with functionalized olefinic monomers.14b,16
Recently, we prepared transition metal complexes that feature
unsymmetrical chelating ligands in order to develop highly
active new olefin polymerization catalysts. Specifically, we
focused on the incorporation of bidentate ligands that afford
metal complexes with a pair of cis-located sites, a prerequisite
for efficient olefin polymerization. Our efforts have led to a
family of group 4 transition metal complexes possessing two
phenoxy-imine chelate ligands, named “FI Catalysts”, which
display high catalytic performance for olefin polymerization
including living olefin polymerization.22 We describe herein the
catalytic performance of zirconium FI Catalysts for olefin
polymerization.
to afford a phenoxy-imine ligand in approximately 80-100%
yield. Complex formation was achieved by treatment of 2 equiv
of the lithium salt of the phenoxy-imine ligand with ZrCl4.
This route utilizes materials that are easily prepared, are
relatively stable, and display high reactivity. The overall yield
for the three steps is very good.
Results and Discussion
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phenol,23 its condensation with an appropriate primary amine
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derivatives with paraformaldehyde in the presence of a base
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Zr Complexes with Phenoxy-Imine Chelate Ligands
J. Am. Chem. Soc., Vol. 123, No. 28, 2001 6849
Olefin Polymerization Using Complex 1. A zirconium
complex having two 3-tert-butylsalicylideneaniline ligands, bis-
[N-(3-tert-butylsalicylidene)anilinato]zirconium(IV)dichloride (1),
was investigated as an ethylene polymerization catalyst using
methylalumoxane (MAO) as a cocatalyst at 25 °C under
ethylene at atmospheric pressure. The results are summarized
in Table 1.
Complex 1 displayed an activity of 197 kg of polymer/mmol
of cat‚h (entry 1), which is much higher than the activity
displayed by Cp2ZrCl2 (entry 7) at the same catalyst concentra-
tion. Difficulty with stirring was encountered for entry 1 because
of the large amount of polyethylene produced. Accordingly,
screens were run with reduced catalyst concentrations in order
to obtain a more accurate activity for complex 1. As a result,
complex 1 was found to display a very high activity of 550 kg
of polymer/mmol of cat‚h with a viscosity average molecular
weight (Mv) value of 0.9 × 104. The activity obtained at reduced
catalyst concentration (550 kg of polymer/mmol of cat‚h, entry
2) was ∼20 times larger than that exhibited by Cp2ZrCl2 at 25
°C. The molecular weight distribution (Mw/Mn) of the polymer
obtained from complex 1 was 2.06, suggesting that the polymer
is produced by a single active species.2d Transition melting
temperature (Tm) of the polymer was 128 °C. Analysis using
13C NMR spectroscopy indicates that the polymer is a linear
Figure 1. Relationship between the polymerization time and the
polymer yield obtained with complex 1/MAO. Conditions: 25 °C, 0.1
MPa ethylene pressure; solvent, toluene 400 mL; complex 1, 0.08 µmol;
MAO (A1), 1.25 mmol.
polyethylene having virtually no branching (see Supporting
Information). Infrared spectroscopy reveals a vinyl end group
concentration of ∼2.4/1000 carbon atoms, which suggests that
â-hydrogen transfer is the main termination pathway. Increasing
Al/Zr ratio from 6250/1 to 312 500/1 gave rise to no significant
changes in the catalytic performance, except the activity in entry
1 (see Table 1, caption b). This observation confirms that chain
transfer to aluminum does not play a dominant role in chain
termination.
To investigate the catalytic lifetime of complex 1, ethylene
polymerizations were conducted for 5, 15, and 30 min. The
relationship between the polymerization time and the polymer
yield indicates that the 1/MAO catalyst has a catalytic lifetime
of at least 30 min, as shown in Figure 1.
The effects of the polymerization temperature on the catalytic
activity of 1/MAO were studied. The results were compared
with those for Cp2ZrCl2 (Figure 2). In the case of Cp2ZrCl2,
the activity was 7 kg of polymer/mmol of cat‚h at 0 °C and
gradually increased to ∼100 kg of polymer/mmol of cat‚h at
75 °C. In comparison, 1/MAO provided 295 kg of polymer/
mmol of cat‚h activity at 0 °C. Moreover, its activity increased
to a maximum of 587 kg of polymer/mmol of cat‚h at 40 °C.
Above 40 °C, the activity decreased. However, over a temper-
ature range of 0 to 75 °C, the activity remained above 100 kg
of polymer/mmol of cat‚h.
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J. P.; Williams, D. J.; Howard, P. Chem. Commun. 1998, 313-314. (i)
Leon, Y. M.; Park, S. J.; Heo, J.; Kim, K. Organometallics 1998, 17, 3161-
3163.
In addition to MAO, the catalytic performance of complex 1
with Ph3CB(C6F5)4/i-Bu3Al as the cocatalyst was investi-
gated.24,25 This catalyst system gave unexpectedly high molec-
3
ular weight polyethylene. At 25 °C, complex 1 with Ph CB-
(C6F5)4/ i-Bu3Al resulted in an Mv value of 383 × 104 with 4
kg of polymer/mmol of cat‚h. Furthermore, at 50 °C, this catalyst
system produced exceptionally higher molecular weight poly-
ethylene (Mv 505 × 104) with 11 kg of polymer/mmol of cat‚h.
In contrast, Cp2ZrCl2 with Ph3CB(C6F5)4/i-Bu3Al produced
(22) (a) Fujita, T.; Tohi, Y.; Mitani, M.; Matsui, S.; Saito, J.; Nitabaru,
M.; Sugi, K.; Makio, H.; Tsutsui, T. Europe Patent, EP-0874005, 1998. (b)
Matsui, S.; Tohi, Y.; Mitani, M.; Saito, J.; Makio, H.; Tanaka, H.; Nitabaru,
M.; Nakano, T.; Fujita, T. Chem. Lett. 1999, 1065-1066. (c) Matsui, S.;
Mitani, M.; Saito, J.; Tohi, Y.; Makio, H.; Tanaka, H.; Fujita, T. Chem.
Lett. 1999, 1163-1164. (d) Matsui, S.; Mitani, M.; Saito, J.; Matsukawa,
N.; Tanaka, H.; Nakano, T.; Fujita, T. Chem. Lett. 2000, 554-555. (e) Saito,
J.; Mitani, M.; Matsui, S.; Kashiwa, N.; Fujita, T. Macromol. Rapid
Commun. 2000, 21, 1333-1336. (f) Saito, J.; Mitani, M.; Matsui, S.;
Kashiwa, N.; Fujita, T. Macromol. Rapid Commun. 2000, 21, 1333-1336.
(g) Matsui, S.; Fujita, T. Catal. Today 2001, 66, 61-71. (h) Matsukawa,
N.; Matsui, S.; Mitani, M.; Saito, J.; Tsuru, K.; Kashiwa, N.; Fujita, T. J.
Mol. Catal. A 2001, 169, 99-104. (i) Yoshida, Y.; Matsui, S.; Takagi, Y.;
Mitani, M.; Nitabaru, M.; Nakano, T.; Tanaka, H.; Fujita, T. Chem. Lett.
2000, 1270-1271. (j) Saito, J.; Mitani, M.; Mohri, J.; Yoshida, Y.; Matsui,
S.; Ishii, S.; Kojoh, S.; Kashiwa, N.; Fujita, T. Angew. Chem. Int. Ed., in
press. (k) Saito, J.; Mitani, M.; Mohri, J.; Ishii, S.; Yoshida, Y.; Matsugi,
T.; Kojoh, S.; Nashiwa, N.; Fujita, T. Chem. Lett. 2001, 576-577.
(23) Wang, R. X.; You, X. Z.; Merg, Q. J.; Minz, E. A.; Bu, X. R. Synth.
Commun. 1994, 24, 1757-1760.
(20) Stephan, D. W.; Guerin, F.; Spence, R. E. V. H.; Koch, L.; Gao,
X.; Brown, S. J.; Swabey, J. W.; Wang, Q.; Xu, W.; Zoricak, P.; Harrison,
D. G. Organometallics 1999, 18, 2046-2048.
(21) Hakala, K.; Lo¨fgren, B.; Polamo, M.; Leskela¨, M. Macromol. Rapid
Commun. 1997, 18, 635-638.
(24) Chen, E. Y.; Marks, T. J. Chem. ReV. 2000, 100, 1391-1434.

6850 J. Am. Chem. Soc., Vol. 123, No. 28, 2001
Matsui et al.
Table 2. Ethylene Polymerization with 1 or Cp2ZrCl2 Using Ph3CB(C6F5)4/ i-Bu3Al as a Cocatalysta
cocatalyst (µmol)
complex
temp
yield
(g)
Mν
entry
(µmol)
Ph3CB(C6F5)4
i-Bu3Al
(°C)
activityb
× 10-4
1
2
3
4
1 (2.5)
1 (2.5)
Cp2ZrCl2 (0.5)
Cp2ZrCl2 (0.5)
5.0
5.0
1.0
1.0
100
100
250
250
25
50
25
50
0.84
2.31
0.77
0.87
4
11
18
21
383
505
59
36
a Conditions: 0.1 MPa ethylene pressure; solvent, toluene 250 mL; polymerization time, 5 min. b Activity, kg of polymer/mmol of cat‚h.
Scheme 2
treatment of complex 1 with MAO followed by treatment with
water quantitatively gave 3-tert-butylsalicylideneaniline [phe-
noxy-imine]. These facts suggest that, by using Ph3CB(C6F5)4/
i-Bu3Al as a cocatalyst, the active species derived from complex
1 may have a phenoxy-amine ligand, which was produced from
the reduction of a phenoxy-imine ligand by i-Bu3Al or
aluminum hydride compounds, contaminant in i-Bu3Al, which
work as a reducing reagent.27
Complex 1 using MAO or Ph3CB(C6F5)4/i-Bu3Al as a
cocatalyst was also found to exhibit high catalytic performance
for ethylene-propylene copolymerization.28 When MAO was
used as a cocatalyst, complex 1 produced a low molecular
weight copolymer, Mv 0.5 × 104, with 22 kg of polymer/mmol
of cat‚h activity at 10.1 mol % propylene content. In contrast,
using Ph3CB(C6F5)4/i-Bu3Al as a cocatalyst, complex 1 produced
a high molecular weight copolymer, Mv 109 × 104, with 8 kg
of polymer/mmol of cat‚h activity at 20.7 mol % propylene
content (see Table 3).
Study of Molecular Stereochemistry for Complex 1. The
stereochemical structure of complex 1 was predicted using DFT
calculations. Because zirconium complex 1 could exhibit five
possible isomeric structures (cis-I, -II, -III, trans-I, -II), DFT
calculations were performed to determine the most plausible
one. The relative formation energies of these five isomers are
listed in Scheme 3.
Figure 2. Relationship between the polymerization temperature and
the activity. Conditions: 0.1 MPa ethylene pressure; complex amount,
1 0.02 µmol, Cp2ZnCl2 0.2 µmol, cocatalyst MAO (A1) 1.25 mmol;
solvent, toluene 250 mL; polymerization time, 5 min.
polyethylene having an Mv value of 59 × 104 and 36 × 104
with activity values of 18 and 21 kg of polymer/mmol of cat‚h
at 25 and 50 °C, respectively. As far as we know, the molecular
weight value, 505 × 104, displayed by complex 1 with Ph3CB-
(C6F5)4/i-Bu3Al is one of the largest values displayed by
homogeneous olefin polymerization catalysts.5a,26 From these
polymerization experiments, it is readily apparent that the choice
of cocatalyst can have a dramatic effect on catalyst performance
(see Table 2).24
Considering the observed difference in catalytic performance
as a result of using MAO and Ph3CB(C6F5)4/i-Bu3Al as
cocatalysts, the localized structures of the active species may
be modified depending on the aluminum species employed.
Treatment of complex 1 with 30 equiv of i-Bu3Al in toluene at
25 °C, followed by treatment with water, exclusively afforded
N-phenyl-2-hydroxy-3-tert-butylbenzylamine [phenoxy-amine]
as an organic material (see Scheme 2). Alternatively, the
Of these, the structure cis-I was found to be the most
preferred. As shown in Figure 3a, the short Zr-O bonds are
trans to each other in the structure cis-I.6e This arrangement
reduces steric congestion of the ligands and maximizes the
opportunity for O to Zr π-bonding through the utilization of
different Zr d-orbitals.
(25) (a) Deck, P. A.; Beswick, C. L.; Marks, T. J. J. Am. Chem. Soc.
1998, 120 1772-1784. (b) Jia, L.; Yang, X.; Stern, C. L.; Marks, T. J.
Organometallics 1997, 16, 842-857. (c) Xie, Z.; Manning, J.; Reed, R.
W.; Mathur, R.; Boyd, P. D. W.; Bensi, A.; Reed, C. A. J. Am. Chem. Soc.
1996, 118, 2922-2928. (d) Jia, L.; Yang, X.; Ishihara, A.; Marks, T. J.
Organometallics 1995, 14, 5-7. (e) Jia, L.; Yang, X.; Stern, C. L.; Marks,
T. J. Organometallics 1994, 13, 3755-3757. (f) Stauss, S. H.; Chem. ReV.
1993, 93, 927-942. (g) Chien, J. C. W.; Tsai, W. M.; Rausch, M. D. J.
Am. Chem. Soc. 1991, 113, 8570-8571. (h) Yang, X.; Stern, C. L.; Marks,
T. J. Organometallics 1991, 10, 840-842. (i) Ewen, J. A.; Elder, M. J.
Eur. Pat. Appl. 426637, 1991; Chem. Abstr. 1991, 115, 136987c, 136988d.
(j) Hlatky, G. G.; Upton, D. J.; Turner, H. W. U.S. Pat. Appl. 459921,
1990; Chem. Abstr. 1991, 115, 256897v.
The calculations suggested that the two oxygen atoms occupy
trans positions (O-Zr-O* angle, 168.8°), whereas the two
nitrogen atoms and the two chlorine atoms were situated in cis
positions (N-Zr-N* angle, 77.0°; Cl-Zr-Cl* angle, 103.2°).
(27) (a) Giacomelli, G.; Caporusso, A. M.; Lardicci, L. Tetrahedron Lett.
1981, 22, 3663-3666. (b) Caporusso, A. M.; Giacomelli, G.; Lardicci, L.
J. Org. Chem. 1982, 47, 4640. (c) Overman L. E. McCready R. J.
Tetrahedron Lett. 1982, 23, 2355-2358.
(28) For propylene polymerization at 25 °C at atmospheric pressure,
complex 1/MAO produced an oligomer with an activity of 324 g/mmol of
cat‚h, whereas complex 1/Ph3CB(C6F5)4/i-Bu3Al provided isotactic polypro-
pylene (Mw 20.6 × 104; Tm 101.6 °C; mm ) 73.4%) with an activity of 68
g/mmol of cat‚h.
(26) Suzuki, N.; Masubuchi, Y.; Yamaguchi, Y.; Kase, T.; Miyamoto,
K.; Horiuchi, A.; Mise, T. Macromolecules 2000, 33, 754-759.

Zr Complexes with Phenoxy-Imine Chelate Ligands
J. Am. Chem. Soc., Vol. 123, No. 28, 2001 6851
a
Table 3. Ethylene-Propylene Copolymerization Using 1 or Cp2ZrCl2
yield
(g)
propylene
content (%)
Mν
c
entry
complex
cocatalyst
activityb
× 10-4
Mw/Mn
1
2
3
4
1
MAO
MAO
4.66
4.54
1.63
1.48
22
22
8
10.1
25.6
20.7
11.5
0.5
0.8
109
13
2.45
3.34
1.83
1.86
Cp2ZrCl2
1
Cp2ZrCl2
Ph3CB(C6F5)4/ i-Bu3Al
Ph3CB(C6F5)4/ i-Bu3Al
7
a Conditions: 50 °C, 0.1 MPa; solvent, toluene 250 mL; polymerization time, 5 min; complex 2.5 µmol; cocatalyst MAO 1.25 mmol, Ph3CB(C6F5)4
5 µmol/i-Bu3Al 0.275 mmol. b Activity, kg of polymer/mmol of cat‚h. c Determined by GPC.
Figure 3. Structure of complex 1. X-ray analysis: Thermal ellipsoids
are shown at 50% probability level. Hydrogen atoms and a diethyl ether
molecule of crystal are omitted for clarity.
Figure 4. Calculated structure of ethylene coordinated active species
derived from complex 1.
Scheme 3
of the X-ray structural analysis, suggesting that DFT calculation
is an effective tool for analyzing the structure of a zirconium
complex bearing two phenoxy-imine ligands.
Thus, an active species derived from complex 1 for ethylene
polymerization was studied on the basis of DFT calculations to
determine why complex 1 displayed exceptionally high ethylene
polymerization activity. As indicated by the X-ray analysis as
well as the DFT calculations, the two chlorine atoms of complex
1 are in a cis configuration. DFT calculations suggest that a
methyl cationic complex derived from complex 1 has two
available cis-located sites needed for efficient olefin polymer-
ization (Figure 4). In addition, the calculations indicate that the
Zr-N bond distances trans to the alkyl chain lengthen consider-
ably during the polymerization process (stage A, 2.232 Å; stage
B, 2.337 Å), whereas the corresponding Zr-O distances remain
practically unchanged (stage A, 2.032 and 2.025 Å; stage B,
2.011 and 2.023 Å). Changes in the Zr-N bond distance may
result from electronic requirements as well as steric requirements
and may play a role for displaying high activity.
Catalytic Performance of the Derivatives of Complex 1.
Complex 1 was demonstrated to have high potential for olefin
polymerization. In addition, the steric and electronic environ-
ments of the metal center can be adjusted by modifying the
ligand structure, because the phenoxy-imine ligand has multiple
sites for introducing or changing the substituent(s). Hence, we
investigated the catalytic performance of the derivatives of
complex 1.
The phenyl unit plane attached to the R3 position swung out
the phenoxy benzene unit, forming a dihedral angle of 60.7°.
The molecular structure of complex 1 was established using
single-crystal X-ray diffraction. As shown in Figure 3b, complex
1 adopted a distorted octahedral structure around the zirconium
center. Selected bond distances, bond angles, and torsion angles
for complex 1 are listed in Table 5. The two oxygen atoms
were situated in trans position (O-Zr-O* angle, 165.5(1)°).
Alternatively, the two nitrogen atoms were located cis to one
another (N-Zr-N* angle, 74.0(1)°), and two chlorine atoms
were also located cis to one another (Cl-Zr-Cl* angle, 100.38-
(5)°). The torsion angle of Zr-N-Ca-Cb was 59.8(4)°.
Consequently, the calculated isomeric structure, cis-I, for
complex 1 was found to be entirely consistent with the results

6852 J. Am. Chem. Soc., Vol. 123, No. 28, 2001
Matsui et al.
Table 4. Ethylene Polymerization Using Complexes 1-15/MAOa
substituent
R2
complex
amt (µmol)
yield
(g)
Mν
engry
complex
R1
R3
activityb
× 10-4
Mw/Mn
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
H
Me
H
t-Bu
t-Bu
Me
i-Pr
Ph
Ph
Ph
Ph
Ph
Ph
0.02
0.02
5.00
5.00
0.02
0.01
0.005
0.50
0.50
5.00
0.10
0.10
5.00
0.10
0.20
0.92
0.55
0.18
0.39
1.19
1.75
1.80
1.68
2.41
0.23
2.03
2.26
trace
0.19
0.72
550
331
0.4
0.9
0.7
0.3
0.6
1.2
1.8
1.5
32
2.06
2.00
2.31
2.48
2.69
7.20
1.88
2.13
2.61
d
H
0.9
Me
Me
Me
H
H
H
H
H
H
Me
cumyl
amantyl
cumyl
cumyl
t-Bu
714
2096
4315
40
58
0.1
cyclohexyl
2-Me-C6H4
t-Bu
t-Bu
t-Bu
t-Bu
2-i-Pr-C6H4
2-t-Bu-C6H4
3,5-di-t-Bu-C6H-
4-t-Bu-C6H4
2,6-di-i-Pr-C6H3
2-i-Pr-C6H4
2-i-Pr-C6H4
113
>274c
2.6
244
271
1.79
2.03
0.7
t-Bu
adamantyl
cumyl
23
43
153
220
d
d
a Conditions: 25 °C, 0.1 MPa ethylene pressure; MAO (Al), 1.25 mmol; solvent, toluene 250 mL; polymerization time, entries 1-9, 11, 12, 14,
and 15 5 min, entries 10 and 13 30 min. b Activity, kg of polymer/mmol of cat‚h. c Obtained from the polyethylene soluble in Decalin under
intrinsic viscosity measurement conditions. d Polymer did not dissolve wholly in o-dichlorobenzene under GPC measurement conditions.
Table 5. Selected Bond Distances, Bond Angles, and Torsion
Angles for Complexes 1 and 5a
1
5
Bond Distances (Å)
1.985(2)
Zr-O
Zr-N
Zr-Cl
1.97(1)
2.38(1)
2.372(4)
2.355(2)
2.4234(9)
Bond Angles (deg)
165.5(1)
O-Zr-O*
N-Zr-N*
Cl-Zr-Cl*
O-Zr-N
O-Zr-N*
O-Zr-Cl
O-Zr-Cl*
N-Zr-Cl
N-Zr-Cl*
Zr-O-Cc
162.4(1)
74.0(1)
100.38(5)
91.10(9)
77.26(8)
95.27(7)
93.99(7)
93.45(6)
164.30(6)
146.5(2)
76.8(1)
98.91(6)
90.2(4)
78.1(4)
96.1(3)
94.8(3)
92.0(3)
167.2(3)
148.5(8)
Figure 5. X-ray structure of complex 5. Thermal ellipsoids are shown
at 50% probability level. Hydrogen atoms are omitted for clarity.
Torsion Angles (deg)
59.8(4)
Table 4 summarizes the catalytic performance of phenoxy-
imine zirconium complexes as a result of introducing and/or
changing substituent(s) at the R1-R3 position.
Zr-N-Ca-Cb
63(1)
a Numbers in parentheses are estimated standard deviations of the
last significant figure. Atoms are labeled as indicated in Figures 3 and
5.
(a) Polymerization Activity. These data demonstrate that
changing the alkyl substituent at the R2 position significantly
affects the polymerization activity. For complex 3 (R2 ) Me)
and complex 4 (R2 ) i-Pr), activities decreased to 0.4 (Mv )
0.3 × 104) and 0.9 kg of polymer/mmol of cat‚h (Mv ) 0.6 ×
104), respectively. Alternatively, replacement of the tert-butyl
group at the R2 position in complex 2 with a sterically larger
adamantyl group or a cumyl group enhanced polymerization
activity and slightly increased Mv, compared to complex 2.
Complexes 5 and 6 displayed activities of 714 (Mv ) 1.2 ×
104) and 2096 kg of polymer/mmol of cat‚h (Mv ) 1.8 × 104),
respectively.
anionic cocatalyst as a result of the introduction of bulkier alkyl
substituents in the R2 position. Separation of cation-anion pair
allows more space for ethylene to coordinate to the metal and
for its insertion into the carbon-metal bond.29 Moreover,
electronically, the separation increases the degree of unsaturation
associated with the cationic active species and thus enhances
the reactivity toward ethylene.25a
Changing the phenyl group on the imine nitrogen of complex
6 to a cyclohexyl group further enhanced activity, probably due
to the electron-donating effects of an aliphatic group at the R3
position. Complex 7, featuring a cyclohexyl group on the imine
nitrogen, afforded an unprecedented activity of 4315 kg of
The X-ray structure of complex 5 is depicted in Figure 5.
The molecular structure of complex 5 is practically the same
as that of complex 1 (Table 5).
The enhancement in catalytic activity may be ascribed to the
effective separation between the cationic active species and the
(29) (a) Mack, H.; Eisen, M. S. J. Orgmet. Chem. 1996, 525, 81-87.
(b) Horton, A. D.; de Width, J. Chem. Commun. 1996, 1375-1376.

Zr Complexes with Phenoxy-Imine Chelate Ligands
J. Am. Chem. Soc., Vol. 123, No. 28, 2001 6853
Scheme 4
polymer/mmol of cat‚h (Mv ) 1.5 × 104) at 25 °C at
atmospheric pressure. This activity corresponds to a catalyst
turnover frequency (TOF) value of 42 900/s‚atm. To the best
of our knowledge, this TOF value is one of the largest not only
for olefin polymerization but for any catalytic reaction at
atmospheric pressure conditions (see Scheme 4).1-4, 30
(b) Molecular Weight of the Polymer. The introduction of
an alkyl group at the ortho position of the phenyl group at the
R3 position dramatically increased the molecular weight values
of polyethylene. Complex 8 (R3, 2-methylphenyl) displayed an
Mv value of 32 × 104. In addition, complex 9 (R3, 2-isopro-
pylphenyl) provided an Mv value of 113 × 104, which is
comparable to that obtained from Cp2ZrCl2. Moreover, complex
10 (R3, 2-tert-butylphenyl) produced high molecular weight
polyethylene, which did not dissolve completely in Decalin
under the intrinsic viscosity measurement conditions. In fact,
the Mv value for the soluble part of the polyethylene produced
by complex 10 was 274 × 104. In contrast, the introduction of
m- or p-tert-butyl(s) on the phenyl group at the R3 position gave
no significant changes in Mv values, as was observed for
complexes 11 and 12. The described increase in the Mv values
is probably due to a decrease in the â-hydride elimination rate
that is a consequence of the increased steric congestion near
the polymerization center.31 Theoretical calculations support this
explanation. Namely, the stabilization energy (∆Eâ) as a result
of â-agostic interaction of the active species, derived from
complex 9 (model B; Figure 6 right), is smaller than that for
complex 1 (model A; Figure 6 left), due to the steric repulsion
of a â-hydrogen and an isopropyl group. Thus, the introduced
o-isopropyl group sterically blocks access to transition state
needed to promote â-hydride elimination.
Figure 6. stabilization energies (∆Eâ) as a result of â-agostic
interaction. Cationic complex models A and B stand for active species
derived from complexes 1 and 9, respectively. All hydrogens except
the â-hydrogen are omitted. An n-propyl group is employed as a model
of a polymer chain.
an adamantyl or a cumyl group at the R2 position, provided
polyethylene having higher Mv values of 153 × 104 and 220 ×
104, respectively.
These results suggest that molecular weight of the polymer
obtained from these catalysts are strongly dependent on the
bulkiness of the substituents placed in the vicinity of active site.
Table 4 together with Table 2 shows that zirconium complexes
having two phenoxy-imine ligands are capable of controlling
the molecular weight of the resulting polymer (Mv 0.3 × 104-
505 × 104) by changing the ligand structure and by the choice
of the cocatalyst (see Scheme 5).
Experimental Section
General Comments. Materials. Dried solvents (diethyl ether,
tetrahydrofuran (THF), dichloromethane, n-hexane, n-pentane) used for
complex synthesis were purchased from Wako Pure Chemical Indus-
tries, Ltd. and used without further purification. Toluene used as a
polymerization solvent (Wako Pure Chemical Industries, Ltd.) was dried
over Al2O3 and degassed by the bubbling of nitrogen gas. Phenol
compounds, amine compounds, and paraformaldehyde for ligand
synthesis were purchased from Aldrich Chemical Co., Inc., Wako Pure
Chemical Industries, Ltd., Acros Organics, or Tokyo Kasei Kogyo Co.,
Ltd. An ethylmagnesium bromide diethyl ether solution and an
n-butyllithium hexane solution were purchased from Tokyo Kasei
Kogyo Co., Ltd. and Kanto Chemical Co., Inc., respectively. ZrCl4,
Cp2ZrCl2 (Wako Pure Chemical Industries, Ltd.) and ZrCl4(THF)2
(Strem Chemicals, Inc.) were used without further purification. Ethylene
and propylene were obtained from Sumitomo Seika Co. and Mitsui
Chemicals, Inc., respectively. Cocatalysts: Methylalmoxane (MAO)
was purchased from Albemarle as a 1.2 M of a toluene solution, and
remaining trimethylaluminum was evaporated in vacuo prior to use.
Ph3CB(C6F5)4 (Asahi Glass Co., Ltd.) and i-Bu3Al (Tosoh Akzo Corp.)
were used as received.
However, complex 13, possessing 2,6-diisopropylphenyl
group at the R3 position, displayed practically no ethylene
polymerization activity, probably due to overwhelming steric
congestion derived from two isopropyl groups. The use of the
2,6-diisopropylphenyl substituent in ligands for olefin polym-
erization catalysts based on late transition metals has been
employed to advantage,14-16 but this is not the case in our
system.
Interestingly, changing the R2 substituent of complex 9 from
the tert-butyl group to an adamantyl group or a cumyl group
further enhanced molecular weight. Thus, complexes 14 and
15, having a 2-isopropylphenyl group at the R3 position, and
Ligand and Complex Analyses. NMR spectra were recorded on
JEOL 270 or NEC-LA500 spectrometers at ambient temperatures.
Chemical shifts for 1H NMR were referenced to internal solvent
resonance and reported relative to tetramethylsilane. The melting point
(mp) of a ligand was measured by a melting point microapparatus from
Yanagimoto Seisakusho. FD-MS spectra were recorded on an SX-102A
(30) Alt, H. G.; Milius W.; Palackal, S. J. J. Organomet, Chem. 1994,
472, 113-118.
(31) DFT calculations suggest that â-hydrogen transfer to ethylene is
sterically unfavored compared with that to the Zr metal for the Zr complexes
used in this study.

6854 J. Am. Chem. Soc., Vol. 123, No. 28, 2001
Matsui et al.
gel using hexane as eluent to give 3-tert-butylsalicylaldehyde (7.33 g,
41.1 mmol) as a pale yellow oil in 82% yield. H NMR (CDCl3): δ
Scheme 5
1
1.43 (s, 9H, t-Bu), 6.95 (dd, 1H, J ) 7.3, 7.3 Hz, aromatic-H), 7.40 (d,
1H, J ) 7.3 Hz, aromatic-H), 7.53 (d, 1H, J ) 7.3 Hz, aromatic-H),
9.88 (s, 1H, CHdO), 11.79 (s, 1H, OH). To a stirred mixture of 3-tert-
butylsalicylaldehyde (2.34 g, 13.4 mmol) and molecular sieves 3A (2
g) in ethanol (20 mL), a solution of aniline (1.41 g, 15.1 mmol) in
ethanol (10 mL) was added dropwise over a 1-min period at room
temperature. The mixture was stirred for 16 h and filtered. The
molecular sieves 3A were washed with ethyl acetate (20 mL). The
combined organic filtrates were concentrated in vacuo to afford a crude
imine compound. Purification by column chromatography on silica gel
using hexane/ethyl acetate (10/1) as eluent gave N-(3-tert-butylsali-
cylidene)aniline (3.23 g, 12.8 mmol) as an orange oil in 95% yield. 1H
NMR (CDCl3): δ 1.47 (s, 9H, t-Bu), 6.82-7.48 (m, 8H, aromatic-H),
8.64 (s, 1H, CHdN), 13.95 (s, 1H, OH).34
(b) Complex Synthesis. To a stirred solution of N-(3-tert-butylsali-
cylidene)aniline (2.533 g, 10.00 mmol) in THF (100 mL) at -78 °C,
a 1.61 M n-butyllithium hexane solution (6.52 mL, 10.50 mmol) was
added dropwise over a 5-min period. The solution was allowed to warm
to room temperature and stirred for 2 h. The resulting solution was
added dropwise over a 30-min period to a stirred solution of ZrCl4-
(THF)2 (1.886 g, 5.00 mmol) in THF (100 mL) at 0 °C. The mixture
was allowed to warm to room temperature and stirred for 15 h. After
removal of the solvent, the product was extracted with CH2Cl2.
Filteration following removal of the volatile gave a yellow solid. The
solid was recrystallized from a dichloromethane/diethyl ether (1/4)
solution at -40 °C to give complex 1 (1.743 g, 2.61 mmol) as
1
fluorescent yellow single crystals in 52% yield. H NMR (CDCl3): δ
1.33-1.59 (m, 18H, t-Bu), 6.78-7.42 (m, 16H, aromatic-H), 8.12 (s,
2H, CHdN). Et2O of crystallization: [1.20 (t, 6H, J ) 5.2 Hz, CH3),
3.48 (q, 4H, J ) 5.2 Hz, CH2)]. Anal. Found: C, 60.86; H, 5.36; N,
3.67; Zr, 12.70. Calcd for ZrC34H36N2O2Cl2 + Et2O: C, 61.60; H, 6.26;
N, 3.78; Zr, 12.31. FD-MS, 664 (M+).
from Japan Electron Optics Laboratory Co., Ltd. Elemental analysis
for CHN was carried out by a CHNO type from Helaus Co. Elemental
analysis for Zr was done using the ICP method with a Shimadzu ICPS-
8000 after dry ashing and dilute nitric acid dissolution.
Polymer Characterization. 13C NMR data for polyethylene were
obtained using o-dichlorobenzene with 20% benzene-d6 as a solvent at
120 °C. The intrinsic viscosity [η] was measured in Decalin at 135 °C
using an Ubbelohde viscometer. Viscosity average molecular weight
(Mv) values of polyethylene were calculated by the following equation:
32 [η] ) 6.2 × 10-4Mv0.7. Mv values of ethylene-propylene copolymers
and molecular weight distribution (Mw/Mn) values of polyethylene and
ethylene-propylene copolymers were determined using a Waters 150-C
gel permeation chromatograph at 145 °C using polyethylene calibration
Bis[N-(3-tert-butyl-5-methylsalicylidene)anilinato]zir-
conium(IV) Dichloride (2). Ligand N-(3-tert-Butyl-5-methylsali-
1
cylidene)aniline as orange crystals: mp 85 °C. H NMR (CDCl3) δ
1.46 (s, 9H, t-Bu), 2.32 (s, 3H, Me), 7.05-7.38 (m, 7H, aromatic-H),
8.59 (s, 1H, CHdN), 13.50 (s, 1H, OH). (2) as fluorescent yellow
crystals: 1H NMR (CDCl3) δ 1.22-1.61 (m, 18H, t-Bu), 2.21-2.36
(m, 6H, Me), 6.78-7.45 (m, 14H, aromatic-H), 7.90-8.11 (m, 2H,
CHdN). Anal. Found: C, 61.87; H, 5.57; N, 3.81. Calcd for
ZrC36H40N2O2Cl2: C, 62.23; H, 5.80; N, 4.03. FD-MS, 694 (M+).
Bis[N-(3-methylsalicylidene)anilinato]zirconium(IV) Dichloride
(3). Ligand N-(3-methylsalicylidene)aniline as a pale orange oil: 1H
NMR (CDCl3) δ 2.36 (s, 3H, Me), 6.70-7.49 (m, 8H, aromatic-H),
8.86 (s, 1H, CHdN), 13.59 (s, 1H, OH). (3) as a green-yellow
powder: 1H NMR (CDCl3) δ 1.50-2.50 (m, 6H, Me), 6.50-7.62 (m,
16H, aromatic-H), 8.00-8.12 (m, 2H, CHdN). Anal. Found: C, 57.90;
H, 4.47; N, 4.74. Calcd for ZrC28H24N2O2Cl2: C, 57.72; H, 4.15; N,
4.81. FD-MS, 582 (M+).
Bis[N-(3-isopropylsalicylidene)anilinato]zirconium(IV) Dichloride
(4). Ligand N-(3-isopropylsalicylidene)aniline as a red-brown oil: 1H
NMR (CDCl3) δ 1.16-1.52 (m, 6H, Me), 3.10-3.69 (m, 1H, CH),
6.78-7.57 (m, 8H, aromatic-H), 8.65 (s, 1H, CHdN), 13.68 (br s, 1H,
OH). (4) as a pale green-yellow powder: 1H NMR (CDCl3) δ 0.80-
1.43 (m, 12H, Me), 2.74-3.32 (m, 2H, CH), 6.13-7.37 (m, 16H,
aromatic-H), 7.89-8.17 (m, 2H, CHdN). Anal. Found: C, 59.86; H,
4.88; N, 4.46. Calcd for ZrC32H32N2O2Cl2: C, 60.17; H, 5.05; N, 4.39.
FD-MS, 638 (M+).
and equipped with three TSKgel columns (two sets of TSKgelGMHHR
-
H(S)HT and TSKgelGMH6-HTL). o-Dichlorobenzene was employed
as a solvent at a flow rate of 1.0 mL/min. Transition melting
temperatures (Tm) of the polymers were determined by DSC with a
Perkin-Elmer DSC-7 differential scanning calorimeter, measured upon
reheating the polymer sample to 200 °C at a heating rate of 10 °C/
min. Propylene contents of the copolymers were determined by IR
analyses.33
Syntheses. Ligand syntheses were carried out under nitrogen in oven-
dried glassware. All manipulations of complex syntheses were per-
formed with exclusion of oxygen and moisture under argon using
standard Schlenk techniques in oven-dried glassware.
Preparation of Bis[N-(3-tert-butylsalicylidene)anilinato]zirconium-
(IV) Dichloride (1). (a) Ligand Synthesis. A 3.0 M ethylmagnesium
bromide diethyl ether solution (18.5 mL, 55.5 mmol) was added
dropwise to a stirred solution of 2-tert-butylphenol (7.51 g, 50.0 mmol)
in THF (40 mL) at room temperature. After the mixture was stirred
for 2 h, toluene (100 mL) was added. After the diethyl ether and the
THF were removed by distillation, a mixture of triethylamine (7.59 g,
75.0 mmol) and paraformaldehyde (3.95 g (95% purity), 125.0 mmol)
in toluene (50 mL) was added, and the mixture was stirred for 2 h at
95 °C. The resulting reaction mixture was poured into 1 N HCl (250
mL) at 0 °C. The organic phase was separated, and the aqueous phase
was extracted with diethyl ether (200 mL × 3). The combined organic
phases were dried over Na2SO4 and evaporated in vacuo to give a
yellow oil, which was purified by column chromatography on silica
Bis[N-(3-adamantyl-5-methylsalicylidene)anilinato]zirconium-
(IV) Dichloride (5). Ligand N-(3-adamantyl-5-methylsalicylidene)-
aniline as an orange powder: mp 53-54 °C. 1H NMR (CDCl3) δ 1.53-
2.30 (m, 15H, adamantyl), 2.34 (s, 3H, Me), 7.01-7.42 (m, 7H,
aromatic-H), 8.59 (s, 1H, CHdN), 13.72 (br s, 1H, OH). (5) as yellow
crystals: 1H NMR (CDCl3) δ 1.30-2.41 (m, 30H + 6H, adamantyl,
Me), 6.80-7.42 (m, 14H, aromatic-H), 8.09 (s, 2H, CHdN). Anal.
(34) Single crystals of complexes 1 and 5 displayed 1H NMR spectra
having small complicated peaks in addition to the peaks assignable for the
structure of type cis-I, suggesting that the zirconium complexes investigated
in this study exist as isomeric mixtures in solution.
(32) Chiang, R. J. Polyme.r Sci. 1959, 36, 91-103.
(33) Tosi, C.; Simonazzi, T. Angew. Makromol. Chem. 1973, 32, 153.

Zr Complexes with Phenoxy-Imine Chelate Ligands
J. Am. Chem. Soc., Vol. 123, No. 28, 2001 6855
Found: C, 68.04; H, 6.53; N, 3.41. Calcd for ZrC48H52N2O2Cl2: C,
67.74; H, 6.16; N, 3.29. FD-MS, 850 (M+).
Table 6. Summary of Crystallographic Data for Complexes
1 and 5
Bis[(3-cumyl-5-methylsalicylidene)anilinato]zirconium(IV) Dichlo-
ride (6). Ligand N-(3-cumyl-5-methylsalicylidene)aniline as an orange
oil: 1H NMR (CDCl3) δ 1.76 (s, 6H, cumyl-Me), 2.38 (s, 3H, aromatic-
Me), 7.11-7.41 (m, 12H, aromatic-H), 8.51 (s, 1H, CHdN), 13.16
(br s, 1H, OH). (6) as a yellow powder: 1H NMR (CDCl3) δ 1.35-
1.65 (m, 12H, cumyl-Me), 1.70-2.11 (m, 6H, aromatic-Me), 6.25-
8.05 (m, 24H + 2H, aromatic-H, CHdN). 0.5Et2O of crystallization:
[1.23 (t, 3H, J ) 5.4 Hz, CH3), 3.49 (q, 2H, J ) 5.4 Hz, CH2)]. Anal.
Found: C, 67.61; H, 5.49; N, 3.18. Calcd for ZrC46H44N2O2Cl2-
(0.5C4H10O): C, 67.35; H, 5.77; N, 3.27. FD-MS, 818 (M+,
ZrC46H44N2O2Cl2).
Bis[(3-cumyl-5-methylsalicylidene)cyclohexylaminato]zirconium-
(IV) Dichloride (7). Ligand N-(3-cumyl-5-methylsalicylidene)cyclo-
hexylamine as a pale yellow powder: mp 106-107 °C. 1H NMR
(CDCl3) δ 1.09-1.68 (m, 10H, cyclohexyl-CH2), 1.73 (s, 6H, cumyl-
Me), 2.33 (s, 3H, aromatic-Me), 3.01-3.22 (m, 1H, cyclohexyl-CH),
6.91-7.30 (m, 7H, aromatic-H), 8.25 (s, 1H, CHdN), 13.40 (br s, 1H,
OH). (7) as a yellow powder: 1H NMR (CDCl3) δ 0.84-2.00 (m, 20H,
cyclohexyl-CH2), 1.83 (s, 6H, cumyl-Me), 1.96 (s, 6H, cumyl-Me), 2.27
(s, 3H, aromatic-Me), 2.37(s, 3H, aromatic-H), 3.47 (m, 2H, cyclohexyl-
CH), 6.90-7.48 (m, 14H, aromatic-H), 8.09 (s, 2H, CHdN). 0.5Et2O
of crystallization: [1.21 (t, 3H, J ) 5.3 Hz, CH3), 3.49 (q, 2H, J ) 5.3
Hz, CH2)]. Anal. Found: C, 66.89; H, 6.22; N, 3.51. Calcd for
ZrC46H56N2O2Cl2(0.5C4H10O): C, 67.19; H, 5.99; N, 3.26. FD-MS, 830
(M+, ZrC46H56N2O2Cl2).
1
5
A. Crystal Data
ZrC34H36N2O2Cl2/
Et2O
empirical formula
ZrC48H52N2O2Cl2
fw
740.92
851.08
crystal color, habit
crystal demens (mm)
crystal system
a (Å)
b (Å)
c (Å)
colorless, prismatic
colorless, prismatic
0.20 × 0.20 × 0.20 0.20 × 0.20 × 0.20
monoclinic
25.464(9)
8.763(6)
17.119(6)
100.00(3)
3761(3)
C2/c (No. 15)
4
monoclinic
15.561(2)
19.636(2)
13.776(1)
95.715(9)
4188.6(8)
Cc (No. 9)
4
â (deg)
V (Å3)
space group
Z
Dcalcd (g/cm3)
F000
1.177
1376.00
4.61
1.350
1776.00
4.31
µ (Mo KR) (cm-1
)
B. Data Collection
0.710 69
λ (Mo Ka radiation)
(Å)
temperature (°C)
2θmax
no. of total reflns
no. of unique reflns
0.710 69
23.0
55.0
4707
23.0
55.0
4983
4602 (Rint ) 0.030) 4812 (Rint ) 0.014)
C. Structure Solution and Refinement
Bis[N-(3-tert-butylsalicylidene)-2′-methylanilinato]zirconium-
(IV) Dichloride (8). Ligand N-(3-tert-butylsalicylidene)-2′-methyla-
niline as an orange oil: 1H NMR (CDCl3) δ 1.50 (s, 9H, t-Bu), 2.49
(s, 3H, Me), 6.81-7.58 (m, 7H, aromatic-H), 8.60 (s, 1H, CHdN),
13.61 (s, 1H, OH). (8) as a yellow powder: 1H NMR (CDCl3) δ 1.08-
1.71 (m, 18H, t-Bu), 2.33-2.45 (m, 6H, Me), 6.44-7.70 (m, 14H,
aromatic-H), 8.08-8.28 (m, 2H, CHdN). Anal. Found: C, 61.85; H,
5.91; N 3.55. Calcd for ZrC36H40N2O2Cl2: C, 62.23; H, 5.80; N, 4.03.
FD-MS, 694 (M+).
Bis[N-(3-tert-butylsalicylidene)-2´ı-isopropylanilinato]zirconium-
(IV) Dichloride (9). Ligand N-(3-tert-butylsalicylidene)-2′-isopropy-
laniline as an orange oil: 1H NMR (CDCl3) δ 1.26 (d, 6H, J ) 5.6 Hz,
Me), 1.48 (s, 9H, t-Bu), 3.46 (q, 1H, J ) 5.6 Hz, CH), 6.85-7.50 (m,
7H, aromatic-H), 8.55 (s, 1H, CHdN), 13.79 (s, 1H, OH). (9) as a
yellow powder: 1H NMR (CDCl3) δ 0.90-1.35 (m, 12H + 18H, Me,
t-Bu), 3.10-3.31 (m, 2H, CH), 6.36-7.70 (m, 14H, aromatic-H), 8.08-
8.29 (m, 2H, CHdN). Anal. Found: C, 63.57; H, 6.41; N, 3.34. Calcd
for ZrC40H48N2O2Cl2: C, 63.98; H, 6.44; N, 3.73. FD-MS, 750 (M+).
Bis[N-(3-tert-butylsalicylidene)-2′-t-butylanilinato]zirconium-
(IV) Dichloride (10). Ligand N-(3-tert-butylsalicylidene)-2′-tert-bu-
tylaniline as an orabge oil: 1H NMR (CDCl3) δ 1.42 (s, 9H, t-Bu),
1.43 (s, 9H, t-Bu), 6.60-7.69 (m, 7H, aromatic-H), 8.49 (s, 1H, CHd
N), 13.57 (s, 1H, OH). (10) as a pale yellow powder: 1H NMR (CDCl3)
δ 1.43 (s, 18H, t-Bu), 1.47 (s, 18H, t-Bu), 6.85-7.60 (m, 12H, aromatic-
H), 8.35 (s, 2H, CHdN). Anal. Found: Zr, 12.06; C, 61.89; H, 6.99;
N, 3.13.35 Calcd for ZrC42H52N2O2Cl2: Zr, 11.71; C, 64.76; H, 6.73;
N, 3.60. FD-MS, 778 (M+).
no. of observns
(I > 3.00σ(I))
no. of variables
refln/param ratio
residuals: R; Rw
goodness-of-fit
indicator
max shift/error in
fit indicator
max peak in final diff 0.44
map (e-/Å3)
3302
3799
211
15.65
0.039; 0.041
1.87
497
7.64
0.033; 0.034
1.13
6.11
3.19
0.19
min peak in final diff -0.36
-0.21
map (e-/Å3)
(s, 18H, t-Bu), 1.37 (s, 18H, t-Bu), 6.68-7.42 (m, 14H, aromatic-H),
8.10 (s, 2H, CHdN). Anal. Found: C, 64.90; H, 6.70; N, 3.95. Calcd
for ZrC42H52N2O2Cl2: C, 64.76; H, 6.73; N, 3.60. FD-MS, 778 (M+).
Bis[N-(3-tert-butylsalicylidene)-2′6′-diisopropylanilinato]zirconium-
(IV) Dichloride (13). Ligand N-(3-tert-butylsalicylidene)-2′6′-diiso-
propylaniline as a yellow oil: 1H NMR (CDCl3) δ 1.18 (d, 12H, J )
5.6 Hz, Me), 1.49 (s, 9H, t-Bu), 2.89-3.13 (m, 2H), 6.81-7.52 (m,
6H, aromatic-H), 8.29 (s, 1H, CHdN), 13.59 (s, 1H, OH). (13) as a
pale yellow powder: 1H NMR (CDCl3) δ 1.21 (d, 24H, J ) 5.6 Hz,
Me), 1.49 (s, 18H, t-Bu), 2.89-3.20 (m, 2H, CH), 6.81-7.60 (m, 12H,
aromatic-H), 8.35 (s, 2H, CHdN). Anal. Found: C, 66.44; H, 7.41;
N, 3.45. Calcd for ZrC46H60N2O2Cl2: C, 66.16; H, 7.24; N, 3.35. FD-
MS, 834 (M+).
Bis[(3-adamantyl-5-methylsalicylidene)-2′-isopropylanilinato]zir-
conium(IV) Dichloride (14). Ligand N-(3-adamantyl-5-methylsali-
cylidene)-2′-isopropylaniline as a yellow powder: mp 160-162 °C.
1H NMR (CDCl3) δ 1.26 (d, 6H, J ) 5.6 Hz, Me), 1.81(s, 6H,
adamantyl-CH2), 2.12 (s, 3H, adamantyl-CH), 2.21 (s, 6H, adamantyl-
CH2), 2.31 (s, 3H, aromatic-CH3), 3.41-3.68 (m, 1H, CH), 6.95-7.47
(m, 6H, aromatic-H), 8.48 (s, 1H, CHdN), 13.50 (s, 1H, OH). (14) as
a yellow powder: 1H NMR (CDCl3) δ 0.80-0.95 (m, 12H, isopropyl-
Me), 1.05-2.40 (m, 30H, adamantyl), 2.32 (s, 6H, aromatic-Me), 3.65-
3.88 (m, 2H, CH), 6.40-7.55 (m, 12H, aromatic-H), 8.02-8.25 (m,
2H, CHdN) Anal. Found: C, 63.57; H, 6.41; N, 3.34. Calcd for
ZrC54H64N2O2Cl2: C, 63.35; H, 6.90; N, 3.00. FD-MS, 935 (M+).
Bis[(3,5-dicumylsalicylidene)-2′-isopropylanilinato]zirconium-
(IV) Dichloride (15). Ligand N-(3, 5-dicumylsalicylidene)-2′-isopro-
pylaniline as a yellow oil: 1H NMR (CDCl3) δ 1.14 (d, 6H, J ) 5.7
Hz, Me), 1.71 (s, 6H, cumyl-Me), 1.72 (s, 6H, cumyl-Me), 3.21-3.29
(m, 1H, CH), 6.88-7.39 (m, 16H, aromatic-H), 8.64 (s, 1H, CHdN),
Bis[N-(3-tert-butylsalicylidene)-3′,5′-di-tert-butylanilinato]zirco-
nium(IV) Dichloride (11). Ligand N-(3-tert-butylsalicylidene)-3′,5′-
di-tert-butylaniline as yellow crystals: mp 136-137 °C. 1H NMR
(CDCl3) δ 1.37 (s, 18H, t-Bu), 1.50 (s, 9H), 6.86-7.49 (m, 6H,
aromatic-H), 8.64 (s, 1H, CHdN), 14.10 (s, 1H, OH). (11) as a yellow
powder: 1H NMR (CDCl3) δ 0.80-1.30 (m, 54H, t-Bu), 6.69-7.51
(m, 12H, aromatic-H), 8.35 (s, 2H, CHdN). Anal. Found: C, 67.57;
H, 7.41; N, 3.34. Calcd for ZrC50H68N2O2Cl2: C, 67.38; H, 7.6; N,
3.14. FD-MS, 890 (M+).
Bis[N-(3-tert-butylsalicylidene)-4′-tert-butylanilinato]zirconium-
(IV) Dichloride (12). Ligand N-(3-tert-butylsalicylidene)-4′-tert-bu-
tylaniline as a yellow oil: 1H NMR (CDCl3) δ 1.36 (s, 9H, tBu), 1.49
(s, 9H, t-Bu), 6.82-7.54 (m, 7H, aromatic-H), 8.63 (s, 1H, CHdN),
14.00 (s, 1H, OH). (12) as a yellow powder: 1H NMR (CDCl3) δ 1.14
(35) Reasonable elemental analysis data for CHN were not obtained since
complex 10 was unstable and decomposed on standing.

6856 J. Am. Chem. Soc., Vol. 123, No. 28, 2001
Matsui et al.
13.16 (br s, 1H, OH). (15) as a yellow powder: 1H NMR (CDCl3); δ.
1.14 (d, J ) 5 Hz, 12H, isopropyl-Me), 1.71, (s, 12H, cumyl-Me),
1.73 (s, 12H, cumyl-Me), 3.70-3.80 (m, 2H, CH), 6.90-7.41 (m, 32H,
aromatic-H), 8.42 (s, 2H, CHdN). Anal. Found: C, 73.57; H, 6.41;
N, 2.34. Calcd for ZrC68H72N2O2Cl2: C, 73.48; H, 6.53; N, 2.52. FD-
MS, 1110 (M+).
X-ray Crystallography. The x-ray structure analyses data were
collected using a Rigaku AFC7R diffractometer, and the structure
solution and refinement were performed by using the TeXan crystal
structure analysis package.36 Experimental data for the X-ray diffraction
analyses of complexes 1 and 5 are summarized in Table 6.
DFT Calculations.37 All calculations were performed at the gradient-
corrected density functional BLYP level by means of the Amsterdam
Density Functional (ADF) program. We used the triple ú STO basis
set on the zirconium and the double ú STO basis set on the N, O, and
n-Pr as a model of a polymer chain and the single ú STO basis set on
the other atoms to calculate the optimized geometries. For energy
calculations, the triple ú STO basis set on the zirconium and the double
ú plus polarization STO basis set on the other atoms were used and
the quasi-relativistic correction was also added.
Ethylene Polymerization. Ethylene polymerization was carried out
under atmospheric pressure in toluene in a 500-mL glass reactor
equipped with a propeller-like stirrer. Toluene (250 mL) was introduced
into the nitrogen-purged reactor and stirred (600 rpm). The toluene
was thermostated to a prescribed polymerization temperature, and then
the ethylene gas feed (100 L/h) was started. After 15 min, polymeri-
zation was initiated by adding a toluene solution of the cocatalyst and
then a toluene solution of catalyst into the reactor with vigorous stirring
(600 rpm). After a prescribed time, isobutyl alcohol (10 mL) was added
to terminate the polymerization, and the ethylene gas feed was
terminated. To the resulting mixture, methanol (1000 mL) and
concentrated HCl (2 mL) were added. The polymer was collected by
filteration, washed with methanol (200 mL), and dried in vacuo at 80
°C for 10 h.
polymerization, except for using ethylene (100 L/h) and propylene (100
L/h) instead of ethylene as the olefin gas feed. After a prescribed time,
isobutyl alcohol (10 mL) was added to terminate the polymerization,
and the olefin gas feed was terminated. To a resulting mixture,
concentrated HCl (2 mL) was added, and the mixture was washed with
water (250 mL × 3) and concentrated in vacuo to give the polymer.
The polymer was dried in vacuo at 130 °C for 10 h.
Conclusion
We demonstrated that a new family of zirconium complexes
with two phenoxy-imine ligands possesses the very high
catalytic performance for ethylene polymerization. Both the
maximum activity value, 4315 kg of polymer/mmol of cat‚h
displayed by bis[N-(3-cumyl-5-methylsalicylidene)cyclohexy-
laminato]zirconium(IV) dichloride/MAO, and the molecular
weight value, Mv 505 × 104, obtained from bis[N-(3-tert-
butylsalicylidene)anilinato]zirconium(IV) dichloride/Ph3CB-
(C6F5)4/i-Bu3Al are some of the highest values exhibited by
homogeneous olefin polymerization catalysts including the
metallocene catalysts. Moreover, we revealed that the zirconium
complexes are capable of controlling the Mv values of poly-
ethylene, Mv 0.3 × 104-505 × 104. Therefore, the zirconium
complexes introduced in this paper have high potential as a new
generation of olefin polymerization catalysts.
Acknowledgment. We thank Professor T. J. Marks, North-
western University, for his fruitful discussions and suggestions.
We also thank T. Hayashi, S. Matsuura, S. Kojoh, Y. Inoue, Y.
Yoshida, Y. Suzuki, K. Sugimura, Y. Nakayama, S. Ishii, J.
Mohri, H. Kaneko, T. Matsugi, M. Kamimura, K. Sugi, A.
Valentine, and M. Mullins for their research and technical
assistance.
Supporting Information Available: Full crystallographic
data for complexes 1 and 5, detailed synthesis data for
complexes 2-15, and 13C NMR spectrum of the polyethylene
produced by complex 1/MAO (PDF). This material is available
free of charge via the Internet at http://pubs.acs.org.
Ethylene-Propylene Copolymerization. Ethylene-propylene co-
polymerization was performed using a similar procedure for ethylene
(36) Altomare, A.; Burla, M. C.; Camalli, M.; Cascarano, M.; Giaco-
vazzo, C.; Guagliardi, A.; Polidori, G. J. Appl. Cryst. 1994, 27, 435-436.
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