Syntheses, characterization, and ethylene polymerization of half-sandwich zirconium complexes with tridentate imino-quinolinol ligands

Article abstract of DOI:10.1021/om101059v

A series of half-sandwich zirconium complexes with imino-quinolinol ligands have been synthesized and characterized. The catalytic behaviors of these complexes toward ethylene polymerization were investigated in the presence of methylaluminoxane (MAO) as

Full text of DOI:10.1021/om101059v

1008 Organometallics 2011, 30, 1008–1012
DOI: 10.1021/om101059v
Syntheses, Characterization, and Ethylene Polymerization of
Half-Sandwich Zirconium Complexes with Tridentate
Imino-Quinolinol Ligands
Ping Hu, Fosong Wang, and Guo-Xin Jin*
Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Department of Chemistry,
Fudan University, Shanghai 200 433, People’s Republic of China
Received November 10, 2010
A series of half-sandwich zirconium complexes with imino-quinolinol ligands have been synthesized
and characterized. The catalytic behaviors of these complexes toward ethylene polymerization were
investigated in the presence of methylaluminoxane (MAO) as a cocatalyst. The catalytic behaviors
were highly affected by the substituent in both cyclopentadienyl and imino-quinolinol ligands.
The Cp analogue complexes CpZr[ONNR]Cl2 (1a-e) exhibited high activities up to 1.34 ꢀ 107 g of
PE (mol of Zr)-1 h-1, whereas the Cp* analogue complexes Cp*Zr[ONNR]Cl2 (2a-e) also showed
moderate activities for ethylene polymerization.
The search for new olefin polymerization catalysts based
on transition-metal complexes is a field of major interest,
involving many academic and industrial research groups.
Nonbridged half-sandwich metal complexes have been con-
sidered as some of the most robust and effective precatalysts
for ethylene polymerization.1-4 These types of complexes
exhibit unique characteristics for the production of novel
polymers that are not prepared by conventional Ziegler-
Natta catalysts,5 as well as by ordinary metallocene type6
and “constrained geometry” half-sandwich metal catalysts
(CGC catalysts).7 The catalytic behavior of these precata-
lysts and the properties of the resultant polyolefin could be
fine-tuned by modifying the substituents of the complex
ligands. Over the past decade, there have been numerous
reports about this research field,2,8-10 and we also have
reported a series of half-metallocene transition-metal com-
plexes containing bidentate11 or tridentate12 ligands exhibit-
ing notable catalytic activities for olefin polymerization.
Commercially, it is of further interest if these catalysts can
be procured in as few steps as possible, from “nonexotic”
starting materials.4 Herein, we report a series of half-sand-
wich zirconium complexes with tridentate imino-quinolinol
ligands which are obtained by easy synthetic routes (Scheme 1).
Moreover, these half-zirconocene complexes can be simply
modified by replacement of the cyclopentadienyl fragment
or monoanionic ancillary ligands. The title catalysts acti-
vated with methylaluminoxane (MAO) showed high activ-
ities in ethylene polymerization.
(1) (a) Mcknight, A. L.; Waymouth, R. M. Chem. Rev. 1998, 98, 2587.
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M. A.; Lopez, A. M.; Mateo, A. C.; Onate, E. Organometallics 2006, 25,
1448.
Results and Discussion
Synthesis and Characterization of the Half-Sandwich Zirconium
Complexes. 8-Hydroxy-2-quinolinecarbaldehyde was prepared
according to the literature procedure.13 The imino-quinolinol
derivatives La-d were prepared by condensation reactions of
(3) (a) Jayaratne, K. C.; Sita, L. R. J. Am. Chem. Soc. 2000, 122, 958.
(b) Huang, J.; Lian, B.; Qian, Y.; Zhou, W.; Chen, W.; Zheng, G.
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Mashima, K. Organometallics 2005, 24, 3375. (d) Zhang, H.; Katao,
S.; Nomura, K.; Huang, J. Organometallics 2007, 26, 5967.
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L. A.; Sita, L. R. J. Am. Chem. Soc. 2001, 123, 6197.
(5) (a) Ziegler, K.; Gellert, H. G.; Zosel, K.; Lehmkuhl, W.; Pfohl, W.
Angew. Chem. 1955, 67, 424. (b) Ziegler, K.; Holzkamp, E.; Breil, H.;
Martin, H. Angew. Chem. 1955, 67, 541. (c) Natta, G. J. Polym. Sci.
1955, 16, 143. (d) Natta, G.; Pino, P.; Corradini, P.; Danusso, F.;
Mantica, E.; Mazzanti, G.; Moraglio, G. J. Am. Chem. Soc. 1955, 77,
1708.
(8) (a) Mahanthappa, M. K.; Cole, A. P.; Waymouth, R. M. Orga-
nometallics 2004, 23, 836. (c) Tamm, M.; Randoll, S.; Herdtweck, E.;
Kleigrewe, N.; Kehr, G.; Erker, G.; Rieger, B. Dalton Trans. 2006, 459.
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Lancaster, S. J. J. Organomet. Chem. 2003, 665, 135. (b) Chan, M. C. W.;
Tam, K.-H.; Zhu, N.; Chiu, P.; Matsui, S. Organometallics 2006, 25, 785.
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444. (b) Zuo, W.; Zhang, S.; Liu, S.; Liu, X.; Sun, W.-H. J. Polym. Sci.,
Part A: Polym. Chem. 2008, 46, 3396. (c) Liu, S.; Yi, J.; Zuo, W.; Wang,
K.; Wang, D.; Sun, W.-H. J. Polym. Sci., Part A: Polym. Chem. 2009, 47,
3154.
(11) (a) Wang, X.; Jin, G.-X. Chem. Eur. J. 2005, 11, 5758. (b) Zhang,
J.; Tang, G.-R.; Jin, G.-X. Chin. Sci. Bull. 2006, 51, 2964. (c) Meng, X.;
Tang, G.-R.; Jin, G.-X. Chem. Commun. 2008, 3178. (d) Huang, Y.-B.;
Jin, G.-X. Organometallics 2009, 28, 4170. (e) Huang, Y.-B.; Jin, G.-X.
Dalton Trans. 2009, 767.
(6) (a) Sinn, H.; Kaminsky, W.; Vollmer, H.-J.; Woldt, R. Angew.
€
Chem., Int. Ed. Engl. 1980, 19, 390. (b) Alt, H. G.; Koppl, A. Chem. Rev.
2000, 100, 1205.
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Organometallics 1990, 9, 867. (b) Shapiro, P. J.; Cotter, W. D.; Schaefer,
W. P.; Labinger, J. A.; Bercaw, J. E. J. Am. Chem. Soc. 1994, 116, 4623.
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Chem. Mater. 2010, 22, 2114.
r
pubs.acs.org/Organometallics
Published on Web 02/18/2011
2011 American Chemical Society

Article
Organometallics, Vol. 30, No. 5, 2011 1009
Figure 1. ORTEP views of the molecular structures of (a) 1b, (b) 1d, and (c) 2d (H atoms are omitted for clarity). Selected bond
˚
distances (A) and angles (deg) are as follows. For 1b: Zr(1)-N(1) = 2.267(3), Zr(1)-N(2) = 2.479(3), Zr(1)-O(1) = 2.063(3),
Zr(1)-Cl(1) = 2.5234(14), Zr(1)-Cl(2) = 2.5004(14); Cl(2)-Zr(1)-Cl(1) = 153.03(4);. For 1d: Zr(1)-N(1) = 2.235(6), Zr(1)-
N(2) = 2.487(6), Zr(1)-O(1) = 2.048(5), Zr(1)-Cl(1) = 2.522(2), Zr(1)-Cl(2) = 2.490(2); Cl(2)-Zr(1)-Cl(1) = 151.78(7). For 2d:
Zr(1)-N(1) = 2.300(2), Zr(1)-N(2) = 2.603(2), Zr(1)-O(1) = 2.067(2), Zr(1)-Cl(1) = 2.4980(9), Zr(1)-Cl(2) = 2.5043(8);
Cl(2)-Zr(1)-Cl(1) = 149.48(3).
Scheme 1. Synthesis of Complexes 1a-e and 2a-e
the 8-hydroxy-2-quinolinecarbaldehyde and corresponding sub-
stituent anilines in refluxing ethanol in good yields.
When the substituent of aniline is an electron-withdrawing
group, a small amount of acid is necessary. Le was prepared
by reaction of 8-hydroxy-2-quinolinecarbaldehyde and 2,6-di-
chlorophenylamine in the presence of a few drops of methanoic
acid.
Crystals of 1b suitable for single-crystal X-ray diffrac-
tion analysis have been obtained by slow diffusion of
hexane into a CH2Cl2 solution of compond 1b. Crystals
of 1d suitable for single-crystal X-ray diffraction analysis
were grown by slow diffusion of hexane into a toluene
solution. Crystals of 2d have been obtained by slow diffusion
of pentane into a toluene solution at low temperature
(-20 °C). Their molecular structures and selected bond
lengths and angles are depicted in Figure 1. Crystallographic
data and processing parameters are given in the Supporting
Information.
The molecular geometries of 1b,d and 2d are quite similar.
If the centroid of the cyclopentadienyl ring is considered as a
single coordination site, the zirconium center has a distorted-
octahedral coordination with the same arrangement of trans
chloride atoms (Cl-Zr-Cl = 153.03(4), 151.78(7), 149.48(3)°).
The zirconium atom in complexes 1b,d and 2d is six-coordi-
nate, with two nitrogen atoms, one oxygen atom, two chlorine
atoms, and a cyclopentadienyl (or pentamethylcyclopenta-
dienyl) ring. The cyclopentadienyl (or pentamethylcyclopen-
tadienyl) group is coordinated at the axial position. The
Zr-N bond distances in the Cp analogues 1b,d are shorter
Organic ligands were characterized by 1H NMR analyses.
By deprotonation of the ligands with excess NaH in THF,
the sodium salts were obtained and reacted further with
CpZrCl3 or Cp*ZrCl3, affording complexes 1a-e and 2a-e
(Scheme 1) in good yields.
All the complexes have been fully characterized by ele-
mental and NMR analyses (see the Experimental Section).
1
On comparison of the H NMR spectra, the peak of Lb at
8.18 ppm (ascribed to the hydroxy proton) disappeared for
complex 1b, indicating the obvious coordination of the
1
oxygen atom to the metal center. The H NMR spectra of
Zr complexes 1a-d and 2a-d show CHdN protons, which
are shifted downfield approximately 0.1-0.04 ppm com-
pared to those of the corresponding free ligands, indicating
the formation of a Zr-N bond.

1010 Organometallics, Vol. 30, No. 5, 2011
Hu and Jin
Table 1. Ethylene Polymerization Results with Zirconium
Complex 1d/MAOa
Table 2. Ethylene Polymerization Results with Zirconium
Complexes 1a-e/MAO and 2a-2e/MAOa
activityb
10-4Mv
entry
procat.
amt of PE (g)
activityb
10-4Mv
c
c
entry
P (atm)
Al/Zr ratio
temp (°C)
1
2
3
4
5
6
7
8
1
1
1
1
1
1
1
1
6
10
10
10
10
10
10
1000
2000
3000
3500
4000
3000
3000
3000
3000
3000
3000
3000
3000
3000
3000
30
30
30
30
30
50
80
100
80
80
80
80
80
80
80
28.8
31.7
33.2
20
15.6
64.8
196
152
2880
8177
8760
13440
13200
7200
5130
18.3
17.7
16.8
16.3
15.9
13.2
10.7
7.2
19.6
26.9
20.1
13.8
8.1
1
2
3
4
5
6
7
8
1a
1b
1c
1d
1e
2a
2b
2c
2d
2e
3.4
4.8
7.1
10.2
1.4
0.6
1.2
1.5
2.2
0.3
2755
3911
5680
8177
1155
497
12.3
20.5
22.8
26.9
17.3
7.6
13.6
16.4
19.7
11.5
977
1200
1777
266
9
9
10
10
11d
12e
13f
14g
15h
a Conditions: 2.5 μmol of procatalyst; 10 atm of ethylene; Al/Zr =
3000; 80 °C; 30 min; toluene (total volume 50 mL). b Activity in kg of PE
(mol of Zr)-1 h-1
meter technique.
.
c Mv measured by the Ubbelohde calibrated viscosi-
27.0
27.1
a Conditions: [Zr] 2.5 μmol, toluene (total volume 50 mL), 30 min.
with elevating temperature due to a faster chain transfer and
termination at higher temperature.
b Activity in kg of PE (mol of Zr)-1 h-1 c Mv measured by the
.
Ubbelohde calibrated viscosimeter technique. d Time 20 min. e Time 10
min. f Time 5 min. g Time 40 min. h Time 60 min.
When the ethylene pressure was increased, the catalytic
activity generally notably improved.17 When the ethylene
pressure was increased from 1 to 10 atm, the polymerization
activity further increased to 8.17 ꢀ 106 g of PE (mol of Zr)-1
h-1 in the current catalytic system (entry 10, Table 1). The
polyethylene obtained under high ethylene pressure usually
exhibits high Mv values (entries 7, 9, and 10, Table 1).
To determine the effect of reaction time on the activity and
molecular weight (Mv) of the resulting polymers, the ethylene
polymerization was conducted over different time periods,
namely, 5, 10, 20, 30, 40, and 60 min (entries 10-15, Table 1);
the highest activity (1.34 ꢀ 107 g of PE (mol of Zr)-1 h-1) was
obtained in a period of 10 min.
Ethylene polymerizations by the title complexes Cp0Zr-
[ONNR]Cl2 (1a-e and 2a-e) in the presence of MAO were
examined to explore the effect of substituents on both the
cyclopentadienyl and the imino-quinolinol ligands with an
Al/Zr molar ratio of 3000 at 80 °C under 10 atm of ethylene,
and the results are summarized in Table 2.
than in the Cp* analogue 2d. The Zr(1)-O(1) bond lengths
of complexes 1b,d and 2d (2.063(3), 2.048(5), 2.067(2) A) are
˚
slightly longer than that of structurally related mono-Cp
14
˚
zirconium complexes (1.954-2.040 A).
Ethylene Polymerization. The complexes 1a-e and 2a-e
can be used as catalysts for ethylene polymerization in the pre-
sence of MAO as a cocatalyst in toluene. Due to better perfor-
mance observed by the precatalyst containing an o-isopropyl
substituent, the precatalyst 1d was investigated in detail by
changing the reaction parameters such as Al/Zr ratio, tem-
perature, and ethylene pressure. The polymerization results
are depicted in Table 1.
We began our studies by searching for the optimal Al/Zr
ratio. The activity data in Table 1 indicate that the optimal
Al/Zr ratio was 3000 (entry 3, Table 1). Increasing the Al/Ti
molar ratio from 1000 to 3000 led to higher activity in
ethylene polymerization and lower molecular weight (Mv)
of the polymer (entries 1-3, Table 1). However, when the Al/
Zr ratio was increased to 3500 or 4000, the catalytic activity
decreased (entries 4 and 5, Table 1). According to the
literature,15 the active species were probably suppressed by
excess MAO; moreover, the amount of AlMe3 contained in
MAO led to deactivation of the catalytic centers.
Using 3000/1 as the optimum Al/Zr ratio, we next inves-
tigated the effect of temperature on activity and molecular
weight (Mv) of the resulting polymers (entries 3 and 6-8,
Table 1). In the metallocene system, the optimal polymeri-
zation temperature for each system depends on the balance
between the propagation rate and the thermal instability.16
At 1 atm of ethylene at an Al/Zr molar ratio of 3000, the
highest activity was observed at 80 °C and slightly decreased
at 100 °C (entries 7 and 8, Table 1). The results indicate that
the ligands with imino-quinolinol backbones play an im-
portant role in stabilizing the active species at high tempera-
ture. However, the molecular weights of polyethylene decrease
The nature of the R group on the ligand has a significant
effect on the catalytic activity and Mv value for the resultant poly-
mer. There are observable effects of the ligand environment, and
the activities of complexes decrease in the order 1d (R = iPr) >
1c (R = Et) > 1b (R = Me) > 1a (R = H) > 1e (R = Cl) and
2d (R = iPr) > 2c (R = Et) > 2b (R = Me) > 2a (R = H) >
2e (R = Cl). The iPr-substituted derivatives showed the highest
activities (entries 4 and 9, Table 2). The steric hindrance caused
by ortho substituents of imino-aryl rings protects the active
species and results in high activity, as seen previously.18 On the
i
other hand, the Pr-substituted derivative 1d has a better
solubility, and its active species are better stabilized, resulting
in a higher activity.15,19 The Cl-substituted derivatives showed
the lowest activities (entries 5 and 10, Table 2). These results
clearly demonstrate that bulky and donating substituents on
the ligands in the ortho position seem to be important for high
(17) (a) Vollmerhaus, R.; Rahim, M.; Tomaszewski, R.; Xin, S.;
Taylor, N. J.; Collins, S. Organometallics 2000, 19, 2161. (b) Xie, G.;
Qian, C. J. Polym. Sci., A: Polym. Chem. 2008, 46, 211. (c) Zuo, W. W.;
Zhang, M.; Sun, W.-H. J. Polym. Sci., Part A: Polym. Chem. 2009, 47,
357. (d) Hong, H.; Zhang, Z.; Chung, T. C. M.; Lee, R. W. J. Polym. Sci.,
Part A: Polym. Chem. 2007, 45, 639. (e) Smit, M.; Zheng, X.; Loos, J.;
Chadwick, J. C.; Koning, C. E. J. Polym. Sci., Part A: Polym. Chem.
2006, 44, 6652.
(14) Sanz, M.; Cuenca, T.; Galakhov, M.; Grassi, A.; Bott, R. K. J.;
Hughes, D. L.; Lancaster, S. J.; Bochmann, M. Organometallics 2004,
23, 5324.
(15) Koltzenburg, S. J. Mol. Catal. A: Chem. 1997, 116, 355.
(16) (a) Junior, P. A. C.; Nele, M.; Coutinho, F. M. B. Eur. Polym. J.
2002, 38, 1471. (b) Antinolo, A.; Carrillo-Hermosilla, F.; Corrochano,
A.; Fernandez-Baeza, J.; Lara-Sanchez, A.; Ribeiro, M. R.; Lanfranchi,
M.; Otero, A.; Pellinghelli, M. A.; Portela, M. F.; Santos, J. V. Orga-
nometallics 2000, 19, 2837.
(18) (a) Chen, E. Y. -X.; Marks, T. J. Chem. Rev. 2000, 100, 1391. (b)
Sun, W.-H.; Liu, S.-F.; Zhang, W.-J.; Zeng, Y.-N.; Wang, D.; Liang,
T.-L. Organometallics 2010, 29, 732.
(19) Bochmann, M. J. Chem. Soc., Dalton Trans. 1996, 255.

Article
Organometallics, Vol. 30, No. 5, 2011 1011
catalytic activity. In addition, the activities of the complexes
CpZr[ONNR]Cl2 are much higher than those of the complexes
Cp*Zr[ONNR]Cl2 suggesting that substituents on the cyclo-
pentadienyl ligand also affect the catalytic activity. Moreover,
the Mv values using the Cp analogues (1a-e) were higher than
those for the Cp* analogues (2a-e).
7.08 (d, 1H, Ar H), 3.49 (sept, 2H, CH iPr), 1.21 (d, 6H, 2CH3),
1.15 (d, 6H, 2CH3).
[ONNCl]H2 (Le). 8-Hydroxy-2-quinolinecarbaldehyde (0.6 g,
3.5 mmol) and 2,6-dichlorophenylamine (0.56 g, 3.5 mmol) were
dissolved in 40 mL of dry methanol in a 100 mL round-bottom
flask. Four drops of methanoic acid were added. The reaction
mixture was refluxed for 10 h and cooled to room temperature.
Purification by column chromatography used 1/10 ethyl ace-
tate/petroleum ether. The product was obtained as yellow
needles in 25% yield. 1H NMR (400 MHz, CDCl3, ppm):
δ 8.63 (s, 1H, NdCH), 8.44 (d, 1H, quin), 8.30 (d, 1H, quin),
8.17 (br, 1H, OH), 7.55 (t, 1H, quin), 7.41 (t, 3H, Ar H), 7.25
(d, 1H, quin), 7.06 (d, 1H, quin).
Conclusions
In summary, a series of half-sandwich zirconium com-
plexes containing a monoanionic tridentate [ONN] ligand
have been synthesized and characterized. A combination of
X-ray crystallographic and spectroscopic studies confirmed
the structure of these half-zirconocene complexes. On acti-
vation with excessive amounts of MAO, these half-sandwich
zirconium complexes exhibit high catalytic activities toward
ethylene polymerization. Remarkably, these zirconium pre-
catalysts exhibited excellent thermal stability at 80 °C, with
regard to industrial requirements.
CpZr[ONNH]Cl2 (1a). To a stirred suspension of NaH (48 mg,
2.0 mmol) in 10 mL of THF was added La (62 mg, 0.25 mmol)
dropwise at 0 °C. Stirring was maintained for 2 h at room
temperature. The mixture was filtered. The filtrate was cooled
to -78 °C and added dropwise to a solution of CpZrCl3 (66 mg,
0.25 mmol) in 15 mL of THF. The resulting suspension was
warmed to room temperature and stirred overnight, and the
solvent was removed under vacuum. The residue was extracted
with 20 mL of toluene to remove NaCl salt. Removal of volatiles
under vacuum left a red powder. Recrystallization of the
product from toluene/pentane afforded 1a as a dark red powder
in a yield of 73%. 1H NMR (400 MHz, CDCl3, ppm): δ 8.52 (s,
1H, NdCH), 8.46 (d, 1H, quin), 7.80 (d, 1H, quin), 7.74 (t, 1H,
quin), 7.41 (d, 1H, quin), 7.29 (d, 1H, quin), 7.25-7.18 (m, 4H,
Ar H), 7.13 (d, 1H, Ar H), 6.55 (s, 5H, Cp H). 13C NMR (CDCl3,
100 MHz): δ 168.24, 165.1, 148.3, 144.29, 142.0, 139.8, 132.7,
130.2, 128.7, 127.4, 126.0, 121.2, 118.7, 116.8, 116.0 ppm. Anal.
Calcd for C21H16Cl2N2OZr: C, 53.16; H, 3.40; N, 5.90. Found:
C, 53.44; H, 3.90; N, 5.69.
Experimental Section
General Considerations. All operations were carried out under
a pure argon atmosphere using standard Schlenk techniques.
Tetrahydrofuran (THF), hexane, pentane, and toluene were
distilled from sodium-benzophenone. Dichloromethane was
distilled from calcium hydride. Commercial reagents, namely,
NaH (60%), CpZrCl3, Cp*ZrCl3, methylaluminoxane (MAO,
1.46 M in toluene), 2-methyl-quinolin-8-ol, and SeO2, were
purchased from Acros Co. 8-Hydroxyquinoline-2-carbaldehyde
was prepared according to the literature procedure.13
CpZr[ONNMe]Cl2 (1b). This complex was prepared as de-
scribed above for 1a, starting from NaH (48 mg, 2.0 mmol), Lb
(70 mg, 0.25 mmol), and CpZrCl3(66 mg, 0.25 mmol). Workup
afforded 1b as orange crystals in a yield of 78%. 1H NMR (400
MHz, CDCl3, ppm): δ 8.53 (s, 1H, NdCH), 8.52 (d, 1H, quin),
7.87 (d, 1H, quin), 7.77 (t, 1H, quin), 7.44 (d, 1H, quin),
7.23-7.15 (m, 3H, Ar H), 7.13 (d, 1H, quin), 6.55 (s, 5H, Cp
H), 2.47 (s, 6H, 2CH3). 13C NMR (CDCl3, 100 MHz): δ 169.4,
164.5, 149.44, 142.3, 139.1, 134.0, 130.9, 129.8, 129.0, 128.2,
127.5, 125.3, 122.0, 118.9, 115.4, 20.1 ppm. Anal. Calcd for
C23H20Cl2N2OZr: C, 54.97; H, 4.01; N, 5.57. Found: C, 54.83;
H, 4.27; N, 5.18.
1H (400 MHz) NMR measurements were obtained on a
Bruker AC 400 spectrometer in CDCl3 solution. Elemental ana-
lyses for C, N, and H were carried out on an Elementar III Vario
EI analyzer.
[ONNH]H2 (La). A mixture of 8-hydroxy-2-quinolinecarb-
aldehyde (0.6 g, 3.5 mmol) and 30 mL of ethanol was heated to
80 °C, and then a solution of phenylamine (0.38 g, 3.5 mmol) in
30 mL of ethanol was added dropwise. The reaction mixture was
refluxed for 6 h and cooled to room temperature. Purification by
column chromatography used 1/3 dichloromethane/ petroleum
ether (1% triethylamine). The product was obtained as yellow
needles in 63% yield. 1H NMR (400 MHz, CDCl3, ppm): δ 8.46
(s, 1H, NdCH), 8.40 (d, 1H, quin), 8.27 (d, 1H, quin), 8.17 (br,
1H, OH), 7.48 (t, 1H, quin), 7.41 (d, 1H, quin), 7.23 (d, 1H,
quin), 7.11-7.07 (m, 4H, Ar H), 7.04 (d, 1H, Ar H).
CpZr[ONNEt]Cl2 (1c). This complex was prepared as de-
scribed above for 1a, starting from NaH (48 mg, 2.0 mmol),
Lc (76 mg, 0.25 mmol), and CpZrCl3 (66 mg, 0.25 mmol).
Workup afforded 1c as orange-red crystals in a yield of 75%.
1H NMR (400 MHz, CDCl3, ppm): δ 8.56 (s, 1H, NdCH), 8.50
(d, 1H, quin), 7.84 (d, 1H, quin), 7.67 (t, 1H, quin), 7.46 (d, 1H,
quin), 7.24-7.17 (m, 3H, Ar H), 7.05 (d, 1H, quin), 6.54 (s, 5H,
Cp H), 3.25-3.17 (m, 1H, CH2), 3.14-3.10 (m, 1H, CH2),
3.05-3.00 (m, 1H, CH2), 2.89-2.85 (m, 1H, CH2), 1.59 (t, 3H,
CH3), 1.12 (t, 3H, CH3). 13C NMR (CDCl3, 100 MHz): δ 167.9,
166.0, 148.5, 143.1, 141.7, 138.7, 134.7, 131.9, 129.2, 128.6,
127.6, 125.2, 122.3, 116.7, 115.1, 24.9, 14.7 ppm. Anal. Calcd
for C25H24Cl2N2OZr: C, 56.59; H, 4.56; N, 5.28. Found: C,
56.63; H, 4.62; N, 5.19.
[ONNMe]H2 (Lb). Using the same procedure as for the
synthesis of La, Lb was obtained as yellow crystals by the
reaction of 8-hydroxy-2-quinolinecarbaldehyde (0.6 g, 3.5 mmol)
and 2,6-dimethylphenylamine (0.42 g, 3.5 mmol) in a yield of 78%.
1H NMR (400 MHz, CDCl3, ppm): δ8.48 (s, 1H, NdCH), 8.42 (d,
1H, quin), 8.28 (d, 1H, quin), 8.18 (br, 1H, OH), 7.56 (t, 1H, quin),
7.41 (d, 1H, quin), 7.23 (d, 1H, quin), 7.11 (d, 2H, Ar H), 7.02 (d,
1H, Ar H), 2.22 (s, 6H, 2CH3).
[ONNEt]H2 (Lc). Using the same procedure as for the synthe-
sis of La, Lc was obtained as yellow crystals by the reaction of
8-hydroxy-2-quinolinecarbaldehyde (0.6 g, 3.5 mmol) and 2,6-
CpZr[ONNiPr]Cl2 (1d). This complex was prepared as de-
scribed above for 1a, starting from NaH (48 mg, 2.0 mmol), Ld
(83 mg, 0.25 mmol), and CpZrCl3(66 mg, 0.25 mmol). Workup
afforded 1d as orange crystals in a yield of 81%. 1H NMR (400
MHz, CDCl3, ppm): δ 8.53 (s, 1H, NdCH), 8.43 (d, 1H, quin),
7.87 (d, 1H, quin), 7.78 (t, 1H, quin), 7.36-7.26 (m, 2H, quin),
7.25-7.15 (m, 3H, Ar H), 6.55 (s, 5H, Cp H), 3.64 (sept, 2H,
CHiPr), 1.41 (d, 6H, 2CH3), 1.04 (d, 6H, 2CH3). 13C NMR
(CDCl3, 100 MHz): δ 168.54, 164.6, 147.3, 142.2, 140.8, 139.1,
137.9, 134.1, 129.0, 128.4, 125.3, 124.6, 121.9, 118.9, 115.6, 27.9,
25.9, 23.2 ppm. Anal. Calcd for C27H28Cl2N2OZr: C, 58.05; H,
5.05; N, 5.01. Found: C, 58.05; H, 5.15; N, 4.87.
1
diethylphenylamine (0.52 g, 3.5 mmol) in a yield of 76%. H
NMR (400 MHz, CDCl3, ppm): δ 8.47 (s, 1H, NdCH), 8.44 (d,
1H, quin), 8.27 (d, 1H, quin), 8.14 (br, 1H, OH), 7.59 (t, 1H,
quin), 7.48 (d, 1H, quin), 7.33 (d, 1H, quin), 7.21 (d, 2H, Ar H),
7.08 (d, 1H, Ar H), 2.58 (m, 4H, 2CH2), 1.27 (t, 6H, 2CH3).
[ONNiPr]H2 (Ld). Using the same procedure as for the synthe-
sis of La, Ld was obtained as yellow crystals by the reaction of
8-hydroxy-2-quinolinecarbaldehyde (0.6 g, 3.5 mmol) and 2,6-
diisopropylphenylamine (0.62 g, 3.5 mmol) in a yield of 72%. 1H
NMR (400 MHz, CDCl3, ppm): δ 8.47 (d, 1H, quin), 8.40 (d,
1H, quin), 8.37 (s, 1H, NdCH), 8.22 (br, 1H, OH), 7.77 (t, 1H,
quin), 7.45 (d, 1H, quin), 7.23 (d, 1H, quin), 7.16 (d, 2H, Ar H),

1012 Organometallics, Vol. 30, No. 5, 2011
Hu and Jin
CpZr[ONNCl]Cl2 (1e). This complex was prepared as de-
scribed above for 1a, starting from NaH (48 mg, 2.0 mmol),
Le (79 mg, 0.25 mmol), and CpZrCl3(66 mg, 0.25 mmol).
Workup afforded 1e as a brown powder in a yield of 61%. 1H
NMR (400 MHz, CDCl3, ppm): δ 8.68 (s, 1H, NdCH), 8.57 (d,
1H, quin), 8.41 (d, 1H, quin), 7.61 (t, 1H, quin), 7.56 (t, 3H, Ar
(m, 1H, CH2), 2.87-2.82 (m, 1H, CH2), 1.50 (t, 3H, CH3), 1.23
(t, 3H, CH3), 1.93 (s, 15H, C5(CH3)5). 13C NMR (CDCl3, 100
MHz): δ 168.1, 166.3, 148.7, 143.6, 142.1, 138.7, 135.1, 131.9,
130.2, 128.1, 127.6, 126.0, 123.1, 116.5, 115.4, 24.8, 14.6, 11.7
ppm. Anal. Calcd for C30H34Cl2N2OZr: C, 59.98; H, 5.70; N,
4.66. Found: C, 59.92; H, 5.74; N, 4.69.
H), 7.25 (d, 1H, quin), 7.06 (d, 1H, quin), 6.55 (s, 5H, Cp H). 13
C
Cp*Zr[ONNiPr]Cl2 (2d). This complex was prepared as de-
scribed above for 1a, starting from NaH (48 mg, 2.0 mmol), Ld
(83 mg, 0.25 mmol), and Cp*ZrCl3 (82.6 mg, 0.25 mmol).
NMR (CDCl3, 100 MHz): δ 168.9, 166.2, 151.0, 146.3, 144.7,
139.1, 135.4, 134.2, 130.7, 129.9, 127.5, 124.8, 121.5, 119.2, 118.5
ppm. Anal. Calcd for C21H14Cl4N2OZr: C, 46.42; H, 2.60; N,
5.16. Found: C, 46.49; H, 2.49; N, 5.35.
1
Workup afforded 2d as orange crystals in a yield of 68%. H
NMR (500 MHz, CDCl3, ppm): δ 8.51 (s, 1H, NdCH), 8.43 (d,
1H, quin), 7.75 (d, 1H, quin), 7.68 (t, 1H, quin), 7.32-7.27 (m,
2H, quin), 7.25-7.23 (m, 2H, Ar H), 7.24 (d, 1H, Ar H), 3.58
(sept, 2H, 2CH(iPr)), 1.92 (s, 15H, C5(CH3)5), 1.33 (d, 6H,
2CH3), 0.97 (d, 6H, 2CH3). 13C NMR (CDCl3, 100 MHz): δ
168.5, 164.8, 146.8, 142.0, 141.0, 138.4, 133.5, 130.7, 129.0,
128.2, 126.2, 123.9, 122.2, 114.9, 114.4, 27.4, 26.0, 22.7, 11.8
ppm. Anal. Calcd for C32H38Cl2N2OZr: C, 61.12; H, 6.09; N,
4.46. Found: C, 61.18; H, 6.11; N, 4.51.
Cp*Zr[ONNH]Cl2 (2a). This complex was prepared as de-
scribed above for 1a, starting from NaH (48 mg, 2.0 mmol), La
(62 mg, 0.25 mmol), and Cp*ZrCl3 (82.6 mg, 0.25 mmol).
Workup afforded 2a as orange crystals in a yield of 75%.
1H NMR (400 MHz, CDCl3, ppm): δ 8.50 (s, 1H, NdCH),
8.45 (d, 1H, quin), 7.78 (d, 1H, quin), 7.74 (t, 1H, quin), 7.40
(d, 1H, quin), 7.29 (d, 1H, quin), 7.25-7.18 (m, 4H, Ar H), 7.11
(d, 1H, Ar H), 1.92 (s, 15H, C5(CH3)5). 13C NMR (CDCl3, 100
MHz): δ 168.3, 165.2, 148.4, 144.2, 141.9, 140.0, 133.0, 129.9,
128.7, 127.8, 125.9, 121.4, 118.6, 116.7, 116.2, 11.9 ppm. Anal.
Calcd for C26H26Cl2N2OZr: C, 57.34; H, 4.81; N, 5.14. Found:
C, 57.37; H, 4.79; N, 5.17.
Cp*Zr[ONNCl]Cl2 (2e). This complex was prepared as de-
scribed above for 1a, starting from NaH (48 mg, 2.0 mmol), Le
(79 mg, 0.25 mmol), and Cp*ZrCl3 (82.6 mg, 0.25 mmol).
Workup afforded 2e as a brown powder in a yield of 55%. 1H
NMR (500 MHz, CDCl3, ppm): δ 8.73 (s, 1H, NdCH), 8.61
(d, 1H, quin), 8.45 (d, 1H, quin), 7.89 (t, 1H, quin), 7.65
(m, 3H, Ar H), 7.25 (d, 1H, quin), 7.06 (d, 1H, quin), 1.92
(s, 15H, C5(CH3)5). 13C NMR (CDCl3, 100 MHz): δ 168.8, 166.6,
152.1, 147.0, 145.1, 138.9, 135.2, 134.8, 130.9, 129.9, 127.1, 124.6,
122.0, 119.7, 118.0, 11.9 ppm. Anal. Calcd for C26H24Cl4N2OZr:
C, 50.90; H, 3.94; N, 4.57. Found: C, 51.32; H, 3.71; N, 4.80.
Cp*Zr[ONNMe]Cl2 (2b). This complex was prepared as de-
scribed above for 1a, starting from NaH (48 mg, 2.0 mmol), Lb
(70 mg, 0.25 mmol), and Cp*ZrCl3 (82.6 mg, 0.25 mmol).
1
Workup afforded 2b as orange crystals in a yield of 70%. H
NMR (400 MHz, CDCl3, ppm): δ 8.56 (s, 1H, NdCH), 8.43 (d,
1H, quin), 7.77 (d, 1H, quin), 7.69 (t, 1H, quin), 7.32 (d, 1H,
quin), 7.25 (d, 1H, quin), 7.25-7.13 (m, 2H, Ar H), 7.01 (d, 1H,
Ar H), 2.36 (s, 6H, 2CH3), 1.92 (s, 15H, C5(CH3)5). 13C NMR
(CDCl3, 100 MHz): δ 168.9, 164.7, 148.4, 142.2, 138.3, 133.5,
130.6, 129.0, 128.2, 126.9, 126.5, 126.1, 125.2, 122.3, 114.9, 20.1,
11.5 ppm. Anal. Calcd for C28H30Cl2N2OZr: C, 58.72; H, 5.28;
N, 4.89. Found: C, 58.74; H, 5.30; N, 4.85.
Acknowledgment. This work was supported by the
Shanghai Science and Technology Committee (Nos.
08DZ2270500, 08DJ1400103), Shanghai Leading Aca-
demic Discipline Project (No. B108), and the National
Basic Research Program of China (Nos. 2009CB825300,
2010DFA41160).
Cp*Zr[ONNEt]Cl2 (2c). This complex was prepared as de-
scribed above for 1a, starting from NaH (48 mg, 2.0 mmol), Lc
(76 mg, 0.25 mmol), and Cp*ZrCl3(82.6 mg, 0.25 mmol). Work-
1
up afforded 2c as orange crystals in a yield of 69%. H NMR
(400 MHz, CDCl3, ppm): δ 8.55 (s, 1H, NdCH), 8.50 (d, 1H,
quin), 7.83 (d, 1H, quin), 7.74 (t, 1H, quin), 7.36 (d, 1H, quin),
7.30 (d, 1H, quin), 7.23-7.11 (m, 2H, Ar H), 7.05 (d, 1H, Ar H),
3.24-3.18 (m, 1H, CH2), 3.12-3.08 (m, 1H, CH2), 3.00-2.95
Supporting Information Available: CIF files, tables and
figures giving crystallographic data, details of the refinement,
and ORTEP diagrams of complexes 1b,d and 2d. This material is
available free of charge via the Internet at http://pubs.acs.org.