Synthesis and Characterization of Novel Tridentate [NOP] Titanium Complexes and Their Application to Copolymerization and Polymerization of Ethylene

Article abstract of DOI:10.1021/om0303808

Novel titanium complexes containing monoanionic [NOP] ligands based on a phenoxyimine ligand and their derivatives were synthesized and characterized. Their performance as ethylene polymerization and copolymerization catalysts were studied. Upon treatment with MMAO, the [NOP]TiCl₃ complexes were robust and highly active for the polymerization of ethylene, even at very low cocatalyst/catalyst ratios. These catalysts also have good copolymerization capabilities.

Full text of DOI:10.1021/om0303808

1684
Organometallics 2004, 23, 1684-1688
Syn th esis a n d Ch a r a cter iza tion of Novel Tr id en ta te
[NOP ] Tita n iu m Com p lexes a n d Th eir Ap p lica tion to
Cop olym er iza tion a n d P olym er iza tion of Eth ylen e
Wei-Qiu Hu,† Xiu-Li Sun,† Cong Wang, Yuan Gao, Yong Tang,* Li-Ping Shi,
Wei Xia, J ie Sun, Hou-Liang Dai, Xiao-Qiang Li, Xiao-Li Yao, and
Xing-Ren Wang
State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry,
Chinese Academy of Sciences, 354 Fenglin Lu, Shanghai 200032, China
Received May 23, 2003
Novel titanium complexes containing monoanionic [NOP] ligands based on a phenoxy-
imine ligand and their derivatives were synthesized and characterized. Their performance
as ethylene polymerization and copolymerization catalysts were studied. Upon treatment
with MMAO, the [NOP]TiCl3 complexes were robust and highly active for the polymerization
of ethylene, even at very low cocatalyst/catalyst ratios. These catalysts also have good
copolymerization capabilities.
Ch a r t 1. F I Ca ta lyst F a m ily
In tr od u ction
Study of the polymerization of olefins by soluble, well-
defined transition-metal complexes is an ever-growing
area.1 Recently much attention has been paid to the
non-metallocene catalysts, which include early-,2 middle-
3
,
and late-transition-metal4 and lanthanide5 species
incorporating non-cyclopentadiene-based ligands. For
non-metallocene systems with group IV metals, com-
plexes derived from chelating diamido ligands2a,c were
reported to be good polymerization catalysts. Very re-
cently, Kol et al.2e,f reported [ONO] and [ONNO] ligand
systems and found that their [ONNO] zirconium com-
plexes were highly active in the polymerization of 1-
hexene. Fujita et al.2g-q developed an FI catalyst family
based on bis(salicylaldiminato) ligands (Chart 1). They
and Coates et al.2g-m reported independently that these
complexes were excellent precatalysts for olefin poly-
merization, including living olefin polymerization and
highly syndiospecific polymerization of propylene. Coates
et al. proposed a mechanistic model for stereocontrolled
propene polymerization.2m-p This catalyst was also
proved to be a good promoter for the synthesis of func-
tional propylene copolymers and block copolymers.2q We
noticed that most of the non-metallocene group 4
precatalysts described above were dihalide (or dialkyl
or monohalide monoalkyl) complexes. In comparison,
only a few of the trihalide (or trialkyl) non-metallocene
precursors were found to be active for olefin polymeri-
zation.6 One of the reasons is probably that the space
of the central metal in the trichloride complex is more
* To whom correspondence should be addressed. E-mail: tangy@mail.
sioc.ac.cn.
† Hu and Sun have made the same contribution to this paper.
(1) For recent reviews see: (a) Britovsek, G. J . P.; Gibson, V. C.;
Wass, D. F. Angew. Chem., Int. Ed. Engl. 1999, 38, 428. (b) Ittel, S.
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Davis, W. M.; Schrock, R. R. J . Am. Chem. Soc. 1997, 119, 3830. (d)
Guerin, F.; McConville, D. H.; Vittal, J . J . Organometallics 1996, 15,
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122, 10706. (f) Tshuva, E. Y.; Goldberg, I.; Kol, M.; Weitman, H.;
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Am. Chem. Soc. 2001, 123, 6847. (h) Matsui, S.; Tohi, Y.; Mitani, M.;
Saito, J .; Makio, H.; Tanaka, H.; Nitabaru, M.; Nakano, T.; Fujita, T.
Chem. Lett. 1999, 1065. (i) Tian, J .; Hustad, P. D.; Coates, G. W. J .
Am. Chem. Soc. 2001, 123, 5134. (j) Mitani, M.; Furuyama, R.; Mohri,
J .-i.; Saito, J .; Ishii, S.; Terao, H.; Kashiwa, N.; Fujita, T. J . Am. Chem.
Soc. 2002, 124, 7888. (k) Mitani, M.; Mohri, J .-I.; Yoshida, Y.; Saito,
J .; Ishii, S.; Tsuru, K.; Matsui, S.; Furuyama, R.; Nakano, T.; Tanaka,
H.; Kojoh, S.-I.; Matsugi, T.; Kashiwa, N.; Fujita, T. J . Am. Chem. Soc.
2002, 124, 3327. (l) Ishii, S.-i.; Saito, J .; Mitani, M.; Mohri, J .-i.;
Matsukawa, N.; Tohi, Y.; Matsui, S.; Kashiwa, N.; Fujita, T. J . Mol.
Catal. A: Chem. 2002, 179, 11. (m) Lamberti, M.; Pappalardo, D.;
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P. D.; Tian, J .; Coates, G. W. J . Am. Chem. Soc. 2002, 124, 3614. (o)
Milano, G.; Cavallo, L.; Guerra, G. J . Am. Chem. Soc. 2002, 124, 13368.
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10.1021/om0303808 CCC: $27.50 © 2004 American Chemical Society
Publication on Web 03/10/2004

Novel Tridentate [NOP] Titanium Complexes
Organometallics, Vol. 23, No. 8, 2004 1685
a
Sch em e 1
a
Reagents and conditions: (i) EtOH, AcOH, reflux; (ii) LiAlH4, 0 °C; (iii) (1) NaH, -78 °C, THF, (2) 0.5 equiv of TiCl4, toluene;
(iv) (1) KH, -78 °C, THF, (2) 1.2 equiv of TiCl4, toluene; (v) (1) NaH, -78 °C, THF, (2) 2.5 equiv of TiCl4.
open than in the similar dichloride species because the
chlorine atom is small, influencing the chain-transfer
process of polymerization. Considering the different
electronic properties and spaces of the reactive sites
between trichloride and dichloride complexes, we de-
signed several trichloride complexes based on the
monoanion ligand 3, in which we installed an intramo-
lecular coordinating P donor as a bulky side arm on the
phenoxy-imine O-N system (Scheme 1) and found that
they are highly active for olefin polymerization. In this
paper, we wish to report the synthesis and structural
characterization of these complexes and their perfor-
F igu r e 1. Molecular structure of 7 (toluene solvent
molecules present in the unit cell are omitted). Selected
bond lengths (Å) and angles (deg): Ti-O ) 1.772(4), Ti-P
) 2.6484(19), Ti-N ) 2.269(5), Ti-Cl(1) ) 2.2938(18), Ti-
Cl(2) ) 2.343(2), Ti-Cl(3) ) 2.2463(19), C(7)-N ) 1.506-
(9); N-Ti-P ) 75.68(15), N-Ti-Cl(1) ) 89.11(15), Cl(3)-
Ti-P ) 91.62, O-Ti-Cl(2) ) 164.57(14), Cl(1)-Ti-Cl(3)
) 103.46(7), Cl(1)-Ti-Cl(2) ) 90.39, Cl(2)-Ti-Cl(3) )
95.89(8).
mance in the polymerization and copolymerization of
olefins in detail.
Resu lts a n d Discu ssion
Liga n d a n d Com p lex Syn th esis. The synthesis of
complexes 5-7 is outlined in Scheme 1. The phenoxy-
imine ligand 3, bearing a diphenylphosphorus group,
was readily synthesized from 3,5-di-tert-butylsalicyal-
dehyde (1) in 69% yield by the Schiff base condensation
of aldehyde 1 with o-(diphenylphosphino)aniline (2),
which was prepared by the known procedure.7 After
deprotonation by alkali-metal hydride at -78 °C in
THF, imine 3 could react with TiCl4 to give the desired
trichloride complex 6 in 78% yield in the presence of a
slight excess of TiCl4 (TiCl4/3 ) 1.2/1.0 (mol/mol)).
Interestingly, we tried to synthesize compound 5, a bis-
(ligand) complex, by using Fujita’s procedure but failed.2p
It was found that this compound could be prepared in
34% yield by using the procedure for the preparation of
complex 6, except the mole ratio of TiCl4/3 was changed
to 0.5. The complex 7 shown in Scheme 1 was prepared
from compound 4 in 50% yield, using the same proce-
dure as that producing complex 6 but with NaH instead
of KH. Ligand 4 was obtained easily in 95% yield from
imine 3 by reduction. The three complexes 5-7 were
all purified easily by recrystallization from toluene.
Ch a r a cter iza tion of Com p lexes 5-7 a n d Sin gle-
Cr ysta l X-r a y Str u ctu r e An a lysis of Com p lex 7. All
the compounds were well characterized by 1H{13C}
NMR, 31P NMR, FT-IR, elemental analysis, and mass
analysis. A single crystal of the complex 7 suitable for
X-ray diffraction study was grown from toluene. As
expected, the molecular structure of compound 7 is
shown in Figure 1 as a titanium trichloride complex
with only one phenoxy-amine ligand featuring a phos-
phorus group. The geometry at the titanium center
could be described as a slightly distorted octahedral
structure in which the five atoms, i.e. Ti, Cl(1), Cl(3),
N, and P, are coplanar to within 0.09 Å. Also, O and
Cl(2) are in a trans configuration. The bond length Ti-P
is 2.6484(19) Å, which is longer than what would be
expected from the covalent radii (rcov(Ti) ) 1.32 Å,
(6) (a) Otero, A.; Fernandez-Baeza, J .; Antinolo, A.; Carrillo-Her-
mosilla, F.; Tejeda, J .; Diez-Barra, E.; Lara-Sanchez, A.; Sanchez-
Barba, L.; Lopez-Solera, I.; Ribeiro, M. R.; Campos, J . M. Organome-
tallics 2001, 20, 2428. (b) Murtuza, S.; Casagrande, O. L., J r.; J ordan,
R. F. Organometallics 2002, 21, 1882. (c) Aaltonen, P.; Seppala, J .;
Matilainen, L.; Leskela, M. Macromolecules 1994, 27, 3136.
(7) Allcock, H. R. Inorganic Syntheses; Wiley: New York, 1989; Vol.
25.

1686 Organometallics, Vol. 23, No. 8, 2004
Hu et al.
Ta ble 1. Resu lts of Eth ylen e P olym er iza tion by
were highly active (entry 1 vs entries 2-18 in Table 1),
with an activity comparable to that of an early-transi-
tion-metal metallocene. Most worthy of note is the fact
that the activity of compound 6 (or 7)/MMAO did not
change very much when the cocatalyst/catalyst ratio
decreased from 1500 to 50 (entries 2-5 for complex
6/MMAO and entries 13-15 for complex 7/MMAO),
suggesting that its activity could be maintained at a
high level even at very low Al/catalyst ratios. For
example, when the cocatalyst is as low as 50 equiv
relative to complex 6, the activity is still higher than 5
× 105 g of PE/((mol of cat.) h atm). This character
distinguished it from most of the existing catalysts. As
presented in Table 1, the temperature tolerances of both
complexes 6 and 7 for performing polymerizations were
rather good (entries 3, 6-11, 13, and 17). Under our
optimized conditions, although good activities of com-
pound 6 were achieved from -30 to 100 °C (entries 3
and 6-11), the best results were obtained by performing
polymerization at 50 °C (entry 3). Noticeably, the
activity of 6 at -30 °C was competitive with that at 100
°C (entries 7 and 11), indicating the robustness of the
catalysts, and the [NOP] ligand could stabilize catalytic
Ti species even at high temperature. Polymer analysis
showed that the molecular weight of polyethylene was
pressure-dependent. As shown in entries 3 and 12 in
Table 1, the molecular weight increased from 22 × 104
(Mw) under atmospheric pressure to 170 × 104 (Mv)
under 7 atm of ethylene at 50 °C. The increase in
polymer molecular mass when the ratio of cocatalyst/
catalyst decreased could be easily explained in terms
of a corresponding decrease in chain transfer. Also, the
molecular weight changed with the polymerization
temperature and it reached to its highest level at 30
°C, which could be tentatively traced to the balance
between chain transfer and chain propagation caused
by the different temperature. 1H and 13C NMR analysis
(spectra given in the Supporting Information) of the
polyethylene produced revealed that the polymer is
highly linear polyethylene with no detectable branches.
This result was also consistent with the analysis of
differential scanning calorimetry (Tm values 131-141
°C). The molecular weight distribution of the polyeth-
ylene determined by GPC was between 1.54 and 3.33,
similar to those of PE produced by single-site catalysts.9
Eth ylen e Cop olym er iza tion . Both complexes 6 and
7 were good catalysts, not only for polymerization of
ethylene but also for copolymerization of ethylene with
other olefins. As shown in Table 2, titanium trichlorides
6 and 7 also exhibited high catalytic activity for the
copolymerization of ethylene with 1-hexene (entries 1-4
and 10) and norbornene (entries 5-9). Moreover, the
molar percentage of the comonomer incorporation could
be tuned by initial comonomer concentration. For ex-
ample, the molar percentage of the hexane incorporation
increased from 5% to 41% while the hexene concentra-
tion was enhanced from 0.27 to 5.33 M (entries 1-4).
Also, the molar percentage of the norbornene incorpora-
tion increased from 4.1% to 35.3% while the norbornene
concentration was enhanced from 0.22 to 3.74 M (entries
5-8). This splendid copolymerization capability may be
Com p lexes 5-7 w ith MMAOa
amt of
cocat
T
time yield
Mw/
Mn
entry procat.b (equiv) (°C) (min)
(g)
activityc Mw
d
1
2
3
4
5
6
7
8
5 (3.6)
6 (2)
6 (2)
6 (2)
6 (2)
6 (2)
6 (2)
6 (2)
6 (2)
6 (2)
6 (2)
6 (23.2)
7 (2)
7 (2)
7 (2)
7 (0.5)
7 (2)
1000
1500
500
100
50
50 60
50 30
50 30
50 30
50 30
30 30
trace
1.41
1.23
0.94
0.25
0.72
0.42
0.74
1.13
0.54
0.52
32.5
0.69
0.40
0.33
0.45
0.36
36.07
nde
14.1
12.3
9.4
2.5
7.2
4.2
7.4
11.3
5.4
5.2
nd
nd
20.8 2.35
23.6 2.08
29.4 2.17
48.0 2.39
72.2 1.53
20.3. 1.91
53.5 1.81
14.0 2.06
14.2 2.11
500
500 -30 30
500
500
500
500
500
500
100
50
0
30
9
60 30
70 30
100 30
50 60
10
11
12f
13
14
15
16
17
18f
7.3
2.43
1.4
170g nd
50
50
50
50
100
5h
41.4
24.0
19.8
22.5 3.33
26.1 2.20
20.4 2.29
5
5
5
5
1000
1000
500
108.0 26.2 1.95
21.6
18.4
7.7
16.0 2.86
1.54
7 (19.6)
50 60
a
General polymerization conditions: total volume 20 mL,
Pethylene ) 1 atm, toluene, MMAO-4 from Akzo-Nobel as cocatalyst.
The amount of catalyst (in µmol) is given in parentheses. c In
b
d
units of 105 g of PE/((mol of cat.) h atm). 104 by GPC relative to
polystyrene standard. e nd ) not determined. f 7 atm of ethylene
pressure in 2 L autoclave; total volume 515 mL and MAO as the
g
cocatalyst. Measured in Decalin at 135 °C using an Ubbelohde
h
viscometer. Stirring stopped at this time due to polymer pre-
cipitation.
r
cov(P) ) 1.06 Å),8 suggesting that the interaction
between Ti-P is somewhat weak, probably due to the
steric crowding of the bulky ligands around the P atom.
In this trichloride complex, the three chlorine atoms
were located cis to one another, which is favorable for
polymerization.
31P NMR gave a single peak for all the ligands and
complexes, indicating that they are pure compounds. 31
P
NMR signals for these compounds ranged from -20 to
40 ppm. In the case of ligand 4, the chemical shift in
31P NMR is -19.54 ppm, while the value for complex 7
shifted to 4.63 ppm, suggesting that the coordination
of the phosphorus atom to the metal center resulted in
its 31P NMR resonance moving downfield. As the 31P
NMR resonance of ligand 3 is -13.63 ppm whereas the
value for complex 5 is 39.69 ppm, we proposed that the
diphenylphosphine group of complex 5 coordinated to
titanium as shown in Scheme 1. This might explain its
lower activity for ethylene polymerization compared
with those of complexes 6 and 7 (entry 1 vs entries 2-12
& entries 13-18 in Table 1).
Eth ylen e P olym er iza tion . The active catalysts
were generated in situ in toluene by addition of modified
methylaluminoxane (MMAO-4 purchased from Akzo-
Nobel) to the precursors in toluene. The polymerization
results are collected in Table 1. As shown in Table 1,
the Ti complex 5 with a bis(phenoxy-imine) ligand was
less effective toward ethylene polymerization. Gratify-
ingly, the titanium catalysts 6 and 7 with a mono-
(phenoxy-imine) ligand for ethylene polymerization
(8) (a) Battaglia, L. P.; Corradi, A. B.; Nardelli, M. Inorg. Chim. Acta
1981, 50, 125. (b) Sikora, D. J .; Rausch, M.; Rogers, R. D.; Atwood, J .
L. J . Am. Chem. Soc. 1981, 103, 982. (c) Shao, M.-Y.; Gau, H.-M.
Organometallics 1998, 17, 4822. (d) Spaltenstein, E.; Palma, P.;
Kreutzer, K. A.; Willoughby, C. A.; Davis, W. M.; Buchwald, S. L. J .
Am. Chem. Soc. 1994, 116, 10308. (e) Ernst, R. D.; Freeman, J . W.;
Stahl, L.; Wilson, D. R.; Arif, A. M.; Nuber, B.; Ziegler, M. L. J . Am.
Chem. Soc. 1995, 117, 5075.
(9) (a) Huang, B. T.; Chen, W. Metallocene Catalysts and Their
Olefin Polymers; Chemical Engineering Press: Beijing, 2000. (b)
Hlatky, G. G. Chem. Rev. 2000, 100, 1347. (c) Ready, T. E.; Gurge, R.;
Chien, J . C. W.; Rausch, M. D. Organometallics 1998, 17, 5236.

Novel Tridentate [NOP] Titanium Complexes
Organometallics, Vol. 23, No. 8, 2004 1687
Ta ble 2. Cop olym er iza tion of Eth ylen e w ith 6/MMAO a n d 7/MMAOa
comonomerb
(amt (M))
procat.
(amt (µmol))
amt of cocat.
(equiv)
time
(min)
yield
(g)
incorporationd
(mol %)
e
entry
activityc
Mw
Mw/Mn
1
2
3
4
5
6
7
8
hex (0.27)
hex (1.06)
hex (2.12)
hex (5.33)
NBE (0.22)
NBE (0.75)
NBE (1.87)
NBE (3.74)
NBE (1.68)
hex (2.05)
6 (9.27)
6 (9.27)
6 (9.27)
6 (9.27)
6 (9.27)
6 (9.27)
6 (9.27)
6 (9.27)
7 (12.3)
7 (9.24)
266
266
266
266
500
500
500
500
500
250
10
10
10
10
30
30
30
30
10
17
1.48
2.11
2.73
2.90
1.81
1.48
1.10
0.65
0.72
1.51
9.58
13.6
17.7
18.7
3.90
3.2
2.4
1.4
3.5
5.8
5.1
15.2
21.0
41.1
4.1
13.6
22.9
35.3
21.1
15.8
3.0
2.2
4.8
2.66
2.42
1.26
2.87
2.96
2.35
2.28
3.25
1.53
2.19
6.2
21.0
20.7
22.9
15.0
12.5
7.0
9
10
a
b
General polymerization conditions: cocat. MMAO-4, 50 °C, 1 atm of ethylene, total volume (E/hexane) 15 mL. Comonomer in feed,
hex.: hexane, NBE: norbornene. c In units of 105 g of PE/((mol of cat.) h atm). Hexene incorporation by 1H NMR and norbornene
d
incorporation by 13C NMR. e 104 determined by GPC versus polystyrene standard.
distilled prior to use. Ethylene was purified before use.
Modified methylaluminoxane was purchased from Akzo Nobel
with 7 wt % Al in toluene and MAO from Akzo Nobel with
15% Al in toluene. Deuterated solvents were dried using
standard procedures and stored in the glovebox. Compound 1
was prepared as described in the literature.10 Other chemicals
were commercially available and used without further puri-
fication.
attributed to the decreased steric hindrance around the
active site with only one chelating ligand.
Con clu sion s
In summary, several novel titanium(IV) complexes
based on a phenoxy-imine ligand with a phosphorus
donor were synthesized and characterized. By introduc-
tion of such a side arm, titanium(IV) complexes with a
chelating mono(ligand) could be formed in which the
steric hindrance around the active site is less than that
of the corresponding complex with bis(ligands) coordi-
nated. In the presence of MMAO, the trichloride com-
plexes described above are robust and highly active for
the polymerization of ethylene to highly linear polyole-
fin. Also, complex 6 could even keep its high activity at
very low cocatalyst/catalyst ratios (50/1 (mol/mol)).
Moreover, these catalysts show good copolymerization
capability of ethylene with 1-hexene and norbornene,
which may be attributed to the open active site.
Syn t h esis of Liga n d 3. To a solution of 3,5-di-tert-
butylsalicyaldehyde (8.2 g, 34.4 mmol) and (o-aminophenyl)-
diphenylphosphine (9.6 g, 34.6 mmol) in ethanol (50 mL) were
added a few drops of acetic acid at room temperature. After
refluxing with stirring for 24 h, the resulting mixture was
cooled to room temperature to afford a yellow solid. The solid
was recrystallized from ethanol/ether to give pale yellow
1
crystals as the desired product 3; yield 11.8 g (69%). H NMR
(CDCl3): δ 1.30 (s, 9H, -C(CH3)3), 1.43 (s, 9H, -C(CH3)3),
7.41-6.85 (m, 16H, Ar H), 8.42 (s, 1H, CHdN). 13C NMR
(CDCl3): δ 29.31, 31.42, 34.03, 35.00, 117.47, 117.49, 118.08,
126.45, 126.80, 127.94, 128.32, 128.42, 128.66, 129.80, 132.88,
133.05, 133.22, 134.11, 134.38, 136.00, 136.13, 136.80, 140.03,
151.48, 151.73, 158.11, 163.35, 163.38. 31P NMR (CDCl3): δ
-13.63 (s). Anal. Calcd for C33H36NOP: C, 80.30; H, 7.35; N,
2.84. Found: C, 80.39; H, 7.59; N, 2.77. EI-MS (m/z (%)): 493
Exp er im en ta l Section
(100) [M+]. IR (KBr): νCdN 1615 cm-1
.
Gen er a l Con sid er a tion s. All manipulations of air- and/
or water-sensitive compounds were carried out under dry
argon using standard Schlenk techniques. NMR spectra were
recorded on a Varian Mercury 300 or Bruker AM300 instru-
ment at 300 MHz (1H), 121.5 MHz (31P), or 75.5 MHz (13C).
Chemical shifts for 1H NMR and 13C NMR were referenced to
residual nondeuterated solvent shifts. 31P NMR chemical shifts
are given in ppm relative to an 85% H3PO4 external reference.
The NMR spectra of all the compounds and complexes were
recorded at ambient temperature unless otherwise stated.
The polymer samples for NMR were prepared by dissolving
the polymer into 1,2-dichlorobenzene in a 5 mm o.d. tube at
120∼135 °C. Mass spectra were obtained using the direct
insertion probe method on a HP5989A instrument operating
at 70 eV. Element analysis was performed on a Vario EL III
instrument. IR analysis was detected with a Perkin-Elmer 983
instrument.
Molecular weights (Mw and Mn) and polydispersities were
determined with a Waters high-temperature GPC 2000 at 150
°C using polystyrene calibration. 1,2,4-Trichlorobenzene was
employed as a solvent. Transition melting temperatures of the
polymers were determined by DSC with a Perkin-Elmer Pyris
1 differential scanning calorimeter, measured upon reheating
the polymer sample to 200 °C at a heating rate of 10 °C/min.
X-ray crystallographic data were collected using a Bruker AXS
D8 X-ray diffractometer.
Syn th esis of Liga n d 4. To a suspension of LiAlH4 (0.3 g,
8.0 mmol) in ether (5 mL) was slowly added a solution of ligand
3 (0.98 g, 2.0 mmol) in ethyl ether (5 mL). After the mixture
was stirred for 2 h at room temperature, water (5 mL) and
H2SO4 (20%; 6 mL) aqueous were added sequentially at 0 °C.
The organic phase was separated and washed with water (5
mL × 3). The aqueous phase was extracted with ether (5 mL
× 3). The combined organic layers were dried with anhydrous
Na2SO4. The solvent was removed under vacuum, and the
residue was purified by column chromatography on silica gel
using petroleum/EtOAc (30:1) as eluent to give the white
product 4; yield 0.94 g (95%). 1H NMR (CDCl3): δ 1.22 (s, 18H,
-C(CH3)3), 4.22 (d, J ) 4.8 Hz, 2H, CH2NH), 4.72 (q, J ) 5.7
Hz, 1H, NH), 6.75-7.56 (m, 16H, Ar H). 13C NMR (CDCl3): δ
29.59, 31.65, 34.16, 34.83, 49.06, 49.08, 113.55, 120.56, 122.13,
123.47, 123.62, 123.85, 123.87, 123.99, 128.68, 128.77, 129.05,
130.46, 133.58, 133.70, 133.73, 133.84, 134.43, 134.52, 136.37,
141.26, 149.64, 149.88, 153.19. 31P NMR (CDCl3): δ -19.54
(s). Anal. Calcd for C33H38NOP: C, 79.97; H, 7.73; N, 2.83.
Found: C, 79.83; H, 7.40; N, 2.76. EI-MS (m/z (%)): 277 (100),
495 (12.86) [M+]. IR (KBr): νN-H 3285 cm-1
.
Syn th esis of Com p lex 5. To a slurry of NaH (48 mg, 2.0
mmol) in THF (5 mL) at -78 °C was added a solution of ligand
3 (986 mg, 2.0 mmol) in 20 mL of THF. The resulting solution
was warmed to room temperature and stirred for 1 h. Then a
solution of TiCl4 (0.11 mL, 1.0 mmol) in 20 mL of toluene was
Ma ter ia ls. Toluene, hexane, hexene, diethyl ether, and
tetrahydrofuran were distilled over sodium benzophenone
ketyl under nitrogen. Methylene chloride was distilled over
P2O5 and CaH2 under nitrogen. Titanium tetrachloride was
(10) Larrow, J . F.; J acobsen, E. N.; Gao, Y.; Hong, Y.; Nie, X.; Zepp,
C. M. J . Org. Chem. 1994, 59, 1939.

1688 Organometallics, Vol. 23, No. 8, 2004
Hu et al.
added dropwise over a 3 h period at -78 °C. The solution was
warmed to room temperature and stirred for 3 h. The solvent
was removed under vacuum to give the crude product. This
crude product was dissolved in anhydrous CH2Cl2 (80 mL). The
resulting mixture was stirred for 15 min and then filtered.
The organic filtrate was concentrated under vacuum and
hexane (2 mL) was added to give the yellow product. The pure
product 5 was obtained by recrystallization from toluene; yield
754 mg (34%). 1H NMR (CDCl3): δ 1.04 (s, 9H, -C(CH3)3), 1.16
(s, 9H, C(CH3)3), 7.62-7.02 (m, Ar H), 8.18 (m, 2H, CHdN,
Ar H). 13C NMR (CDCl3): δ 29.69, 31.19, 34.63, 35.25, 119.91,
125.24, 127.06, 128.17, 128.41, 128.53, 128.98, 129.21, 130.68,
131.45, 132.61, 133.40, 134.12, 134.26, 135.21, 137.32, 146.29,
153.04, 158.38, 161.76, 162.14, 165.24. 31P NMR (CDCl3): δ
39.69 (s). Anal. Calcd for C66H70Cl2N2O2P2Ti: C, 71.80; H, 6.39;
N, 2.54. Found: C, 71.50; H, 6.73; N, 2.38. EI-MS (m/z (%)):
493 (100) [M - TiCl2 - C33H36NOP]+. IR (KBr): νCdN 1607
filtrate was concentrated under vacuum to give a red-brown
solid (crude product). The pure product 7 was obtained by
1
recrystallization from toluene. Yield: 130 mg (50%). H NMR
(CDCl3): δ 1.23 (s, 9H, -C(CH3)3), 1.27 (s, 9H, -C(CH3)3), 3.9
(dd, J ) 13.5, 6 Hz, 1H, CH2), 4.7 (d, J ) 13.5 Hz, 1H, CH2),
7.9-6.7 (m, Ar H), 8.3 (br s, 1H, NH). 31P NMR (CDCl3): δ
4.63. Anal. Calcd for C33H37Cl3NOPTi: C, 61.09; H, 5.75; N,
2.16. Found: C, 61.16; H, 5.79; N, 1.85. EI-MS (m/z (%)): 576
(100), 612 (7.62) [M - Cl] +, 614 (4.54), 616 (0.84). IR (KBr):
νN-H 3167 cm-1
.
Gen er a l P r oced u r e of Eth ylen e P olym er iza tion u n d er
Atm osp h er ic P r essu r e. A solution of complex in toluene was
added to a flame-dried Schlenk flask with toluene saturated
by ethylene. The MMAO solution was injected into the flask
via syringe with stirring. The reaction was quenched after a
period of time, and the polymer was precipitated in acidic
ethanol, filtered, washed with ethanol, and dried at 50 °C
under vacuum to constant weight.
cm-1
.
Syn th esis of Com p lex 6. To a slurry of KH (60 mg, 1.50
mmol) in THF (10 mL) was added a solution of ligand 3 (740
mg, 1.50 mmol) in THF (10 mL) at 0 °C. The resulting
suspension was warmed to room temperature and stirred for
1 h. After the solvent was removed under vacuum, 30 mL of
toluene was added to the residue, followed by a solution of
TiCl4 (0.20 mL, 1.80 mmol) in toluene (10 mL). After the
mixture was stirred for a further 3 h, the solvent was removed
under vacuum, anhydrous CH2Cl2 (20 mL) was added to the
residue, and the mixture was stirred for 15 min and then
filtered. The organic filtrate was concentrated, and then
hexane (2 mL) was added to precipitate the brown-red product;
the pure product 6 was obtained by recrystallization from
toluene. Yield: 760 mg (78%). 1H NMR (CDCl3): δ 1.33 (s, 9H,
-C(CH3)3), 1.51 (s, 9H, -C(CH3)3), 7.76-7.26 (m, 16H, Ar H),
8.74 (s, 1H, CHdN). 13C NMR (CDCl3): δ 29.72, 31.21, 34.64,
35.28, 119.91, 120.01, 125.25, 125.74, 126.19, 127.09, 128.18,
128.41, 128.54, 128.99, 129.18, 129.24, 130.66, 131.01, 131.50,
132.61, 133.38, 134.15, 134.28, 135.32, 136.33, 146.28, 155.89,
156.18, 160.42, 160.49, 165.22. 31P NMR (CDCl3): δ 18.93.
Anal. Calcd for C33H35Cl3NOPTi: C, 61.28; H, 5.45; N, 2.17.
Found: C, 60.36; H, 6.01; N, 2.01. EI-MS (m/z (%)): 591 (100),
610 (25.27) [M - Cl]+, 612 (17.92), 614 (3.00), 492 (19.82) [M
Gen er a l P r oced u r e of Eth ylen e P olym er iza tion u n d er
7 a tm . A 2 L autoclave equipped with a magnetic stirring bar
was first purged by N2 overnight and then charged with the
desired amount of MAO and toluene (500 mL) under nitrogen.
The solution was saturated under 7 atm of ethylene. A solution
of catalyst in toluene (15 mL) was added to the reactor under
a pressure somewhat higher than atmospheric pressure at 50
°C. The pressure of the reactor was raised to 7 atm and
maintained until the reactor was vented. The polymer was
precipitated in acidic ethanol, filtered, washed with ethanol,
and then dried at 50 °C under vacuum to constant weight.
Gen er a l P r oced u r e of Eth ylen e Cop olym er iza tion
u n d er Atm osp h er ic P r essu r e. A flame-dried Schlenk flask
was charged with the desired amounts of toluene, comonomer,
and MMAO. The solution was saturated by ethylene. A
solution of catalyst in toluene was injected into the reactor
via syringe to initiate the polymerization. After the desired
period of time, the reactor was vented. The polymer was
precipitated in acidic ethanol, filtered, washed with ethanol,
and then dried at 50 °C under vacuum to constant weight.
Ack n ow led gm en t. We are grateful for financial
support from the National Natural Sciences Foundation
of China.
- TiCl3] +. IR (KBr): νCdN 1593 cm-1
.
Syn th esis of Com p lex 7. To a slurry of NaH (9.2 mg, 0.4
mmol) in 10 mL of THF at 0 °C was added a solution of ligand
4 (200 mg, 0.4 mmol) in THF (5 mL). The resulting suspension
was warmed to room temperature and stirred for 1 h. Then
the solvent was removed under vacuum. A 40 mL portion of
toluene was added to the residue, and then a solution of TiCl4
(0.11 mL, 1.0 mmol) in toluene (10 mL) was added. After it
was stirred for 3 h, the mixture was filtered and the organic
Su p p or tin g In for m a tion Ava ila ble: Figures giving NMR
spectra of the polymers and tables giving X-ray data for 7. This
material is available free of charge via the Internet at
http://pubs.acs.org.
OM0303808