Reaction of 2,8-bis(o -hydroxyaryl)quinolines with group 4 metal alkyls resulting in three distinct coordination modes of the tridentate ligand. X-ray structure of complexes and performance as precursors in ethylene polymerization catalysis

Article abstract of DOI:10.1021/om4001555

A series of bis(o-hydroxyphenyl)quinolines have been prepared, starting from 2,8-dibromoquinoline. Reaction of these new ligand precursors with group 4 tetrabenzyl complexes MBn₄ results in benzyl substitution of the azine fragment with the formation of amide complexes (M = Ti) or amine complexes with an N-H fragment coordinated to the metal (M = Zr, Hf). The third structural type - Zr complexes where the aromatic system of the precursor remains intact - can be prepared through the reaction of the bis(o-hydroxyphenyl)quinolones with 4 mol of methyllithium, followed by ZrCl₄. The new complexes result in active polymerization catalysts when activated with MAO/borate cocatalysts on silica supports, resulting in polyethylene copolymers with very high molecular weights and multimodal MWDs.

Full text of DOI:10.1021/om4001555

Article
pubs.acs.org/Organometallics
Reaction of 2,8-Bis(o‑hydroxyaryl)quinolines with Group 4 Metal
Alkyls Resulting in Three Distinct Coordination Modes of the
Tridentate Ligand. X‑ray Structure of Complexes and Performance as
Precursors in Ethylene Polymerization Catalysis
Ilya E. Nifant’ev,*,†,‡ Pavel V. Ivchenko,† Vladimir V. Bagrov,† Sandor M. Nagy,*,§ Shahram Mihan,∥
Linda N. Winslow,⊥ and Andrei V. Churakov#
†Chemistry Department, M. V. Lomonosov Moscow State University, Moscow, Russia 119991
‡A. V. Topchiev Institute of Petrochemical Synthesis, RAS, 29 Leninsky prosp., Moscow, Russia 119991
§Lyondell Chemical Company, Houston Technical Center, Channelview, Texas 77530, United States
∥Basell Polyolefine GmbH, Frankfurt am Main, Germany
⊥Equistar Chemicals LP, Cincinnati Technical Center, Cincinnati, Ohio 45249, United States
#N. S. Kurnakov Institute of General and Inorganic Chemistry, RAS, 31 Leninsky prosp., Moscow, Russia 119991
S
* Supporting Information
ABSTRACT: A series of bis(o-hydroxyphenyl)quinolines have
been prepared, starting from 2,8-dibromoquinoline. Reaction of
these new ligand precursors with group 4 tetrabenzyl complexes
MBn4 results in benzyl substitution of the azine fragment with
the formation of amide complexes (M = Ti) or amine complexes
with an N−H fragment coordinated to the metal (M = Zr, Hf).
The third structural typeZr complexes where the aromatic
system of the precursor remains intactcan be prepared
through the reaction of the bis(o-hydroxyphenyl)quinolones
with 4 mol of methyllithium, followed by ZrCl4. The new
complexes result in active polymerization catalysts when
activated with MAO/borate cocatalysts on silica supports,
resulting in polyethylene copolymers with very high molecular weights and multimodal MWDs.
catalyst components. Bis-phenol complexes of the [ONO]
structural type (3; Scheme 1)4 demonstrated good activity in
the polymerization of 1-hexene,5,4b 4-methylpentene,6 vinyl-
cyclohexane,6 and propylene7 and for ethylene/1-hexene
copolymerization.8 After the reported enhanced productivity
of complexes 4 (Scheme 1),5c attributed to an additional donor
fragment, a variety of tetradentate chelates were introduced,
like the Salen [ONNO] ligand in 59 and its structural
analogues[OOOO]10a and [OSSO]10b in 6. In parallel with
the progress in the area of tetradentate ligands, the structural
diversification of the tridentate bis-phenoxy system continued
with the development of bis-phenoxy imine complexes 711 and
bis-aryloxy pyridine complexes 8.12
INTRODUCTION
■
Various approaches toward efficient ligand environment design
in postmetallocene transition-metal systems developed over the
recent decades enabled a remarkable control of polymerization
performance, leading to incorporation of new monomers,
generation of polymers with unique molecular weight,
molecular weight distribution, and branching profiles.1 From
this perspective, ensuring the robustness of the ligand−metal
“assembly” becomes a very important factor in developing
viable new catalysts. The inherent strength of the electro-
positive group 4 metal bonding to oxygen is one of the several
underlying reasons for the continued interest (and progress) in
utilizing the stable aryloxide fragments as stable building blocks,
as illustrated by the mono-Cp titanium complexes 1 of
Nomura2 or Fujita’s phenoxyimine chelate complexes 2
(Scheme 1),3 to name just two “classical” representatives of
this promising class of postmetallocene systems. The chelate
effect further contributes to the robustness of the ligand;
consequently, a large diversity of multidentate topologies have
been introduced in recent years, resulting in interesting
performance when these ligands are tested as polymerization
Recently13 we have introduced a general approach toward
structurally diverse tridentate ligands based on the quinoline
template starting with 2,8-dibromoquinoline. Some of the
intended precursors for complexes of the [ONO] structural
type were bis-phenols 9, which were expected to generate the
Received: February 26, 2013
© XXXX American Chemical Society
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Scheme 1. Aryloxy Group 4 Metal Complexes: Olefin Polymerization Catalysts
tridentate chelate complexes 10, structurally related to the bis-
phenoxy pyridine analogues 8. However, the attempted
interaction of the quinoline bis-phenol proligands with the
tetrabenzyl source of the metal, MBn4 (M = Zr, Hf),
demonstrated that the reaction proceeds in an unexpected
direction, prompting us to undertake an in-depth study of the
new reactions and characterize the unexpected products and
use them as precursors to olefin polymerization catalysts.
Scheme 2. Preparation of Quinoline-Based [ONO] Ligand
Precursors
a
RESULTS AND DISCUSSION
■
Quinoline-Based Ligand Synthesis. Our synthetic
approach was based on 2,8-dibromoquinoline, a strategic
starting material which is easily accessible in three steps from
2-bromoaniline.14 The two bromine atoms of the precursor
have substantially different reactivities, allowing very selective
sequential introduction of substituents, an approach used earlier
during the synthesis of 2-phenyl-8-phenylaminoquinoline14 and
related quinoline-based [CNN]-type ligand precursors used in
the synthesis of group 4 complexes.15 The latter study
demonstrated the effectiveness of Pd-catalyzed Suzuki and
Negishi couplings for introduction of an aryl fragment into the
2-position of the quinoline.
Similarly, the Negishi reaction was used in this work to
prepare the quinoline-based [ONO] ligands of this study.
Commercially available substituted phenols were converted to
the methoxymethyl (MOM) derivatives 11−13 in the first step.
Treatment of 11−13 with butyllithium and ZnCl2 resulted in
zinc−organic derivatives used in the Negishi synthesis along
with 0.5 equiv of 1,8-dibromoquinoline in the case of 11 and 12
and 1 equiv in the case of 13. Hydrolysis of 2,8-bis(MOM-
aryl)quinolines 14 and 15 resulted in the target [ONO] ligand
precursors 16 and 17. The 2-(MOM-aryl)quinoline 18
resulting from 13 was further reacted with the Zn−organic
compound, leading to the “non-symmetric” [ONO] ligand 19
after hydrolysis (Scheme 2).
a
Legend: (i) (1) NaH/THF, (2) MeOCH2Cl; (ii) (1) BuLi/Et2O +
THF, (2) ZnCl2, (3) 2,8-dibromoquinoline, Pd(dba)2, P(o-tolyl)3; (iii)
11 + (1) BuLi and (2) ZnCl2, Pd(dba)2, P(o-tolyl)3; (iv) HCl.
ligands 16, 17, and 19 resulted in predominant formation of
products with structures different from that of the target
structure 10. This is confirmed by an analysis of the products of
hydrolysis of the reaction mixtures 16 + TiBn4 and 16 + ZrBn4,
where the initial ligand 16 is practically absent. In the case of
TiBn4 recrystallization of the 16 + TiBn4 reaction mixture
Group 4 Metal Derivatives: Interaction of [ONO]
ligands with MBn4. Interaction of MBn4 with [ONO]-type
B
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Scheme 3. Group 4 Metal Complexes by Interaction of [ONO] Ligand Precursors with MBn4
resulted in a moderate yield of the product of nucleophilic
addition of the benzyl group at the 4-position of the azine part
of the quinoline ring systemmonobenzyl amido complex 20.
Tetrabenzylzirconium and tetrabenzylhafnium, on the other
hand, in the main resulted in dibenzyl complexes 21−24,
containing a benzyldihydroquinoline ligand with an N−H
fragment (Scheme 3).
Migration of the benzyl group from the zirconium atom with
the formation of a dihydroquinoline fragment was reported
earlier to occur during thermolysis of 8-oxyquinoline-based
ZrBn2 complexes (Scheme 4).16 A similar process at a pyridine
ring was observed during the reaction of ZrBn2(OAr)2 with
2,2′-bipyridine and 1,10-phenanthroline17 (Scheme 4).
oxygen atom to the nitrogen leads to the formation of products
21−24 (Scheme 5).
Computational estimates (DFT, PRIRODA18) of the relative
energies of model compounds 27−29, using methyl groups
instead of benzyl fragments (Table 1), indicate that the cis-
bis(phenoxy) amine complex 28 is thermodynamically more
stable (−24.4 kcal/mol) than the hypothetical intermediate 27
or the trans isomer 29 (−21.3 kcal/mol), in line with the X-ray
structure of complexes 21 and 22.
X-ray Structure Determinations of 20−22. The
structures of Zr (21) and Hf complexes (22) were confirmed
by single-crystal X-ray studies. Selected bond distances and
angles are given in Table 2. As 21 and 22 are isostructural, their
geometrical parameters are close to each other and the same
labeling scheme was adopted (Figure 1). In 21, the central
zirconium atom adopts a distorted-trigonal-bipyramidal coor-
dination environment. Nitrogen atom N(1) and η1-benzyl
group C(61) occupy axial positions, while phenolate oxygen
atoms and η1-benzyl group C(71) lie in equatorial sites.
Analysis of the Cambridge Structural Database (version 5.33)19
shows that Zr−O and Zr−N distances have ordinary values for
terminal Zr−OC6H5 (1.808−2.075 Å, 21 hits) and acyclic Zr←
NHR2 (2.308−2.547 Å, 43 hits) bond lengths. As expected, the
axial bond Zr−C(61) is slightly longer than the equatorial bond
Zr−C(71) (∼0.02 Å). The large values of Zr−O−Ar angles
(148.83(13) and 151.88(13)°) indicate the significant level of
dπ−pπ interactions in these fragments. Of interest, in all
previously reported Zr complexes with terminal −OPh ligands
(21 hits in the CSD) these angles are larger than 138° and
clearly correlate with Zr−O bond lengths. Both benzyl ligands
are η1 coordinated, since Zr−CH2−CPh angles are equal to
108.45(16) and 116.85(15)°. In hafnium complex 22, all
distances involving the metal are slightly shorter than in 21 by
approximately 0.01−0.03 Å. No short intermolecular contacts
were found in the structures of 21 and 22.
The structure of titanium complex 20 is shown in Figure 2.
The coordination polyhedron of Ti represents a distorted
tetrahedron (assuming that the η2-benzyl ligand occupies one
coordination site). According to the CSD, Ti−O and Ti−N
distances lie within normal ranges for terminal Ti−OC6H5
(1.767−1.951 Å, 31 hits) and acyclic Ti−NR2 (1.783−2.251,
mean 1.902 Å, 806 hits) bond lengths. The benzyl ligand is
clearly η2 coordinated, since the Ti−CH2−CPh angle is less than
90° and the C(41)−C(42) distance is shortened to 1.469(6) Å.
A great number of benzyltitanium complexes have been
reported in the CSD to date (64 entries, 127 Ti−Bn bonds).
However, only seven of them contain coordinated Bn ligands
with Ti−CH2−CPh angles less than 90° (namely, DEHQAI,
DEHQUC, DOFMIV, FIGHUZ, LUYYOT, TEDKET, and
ZUJBIP). In these seven complexes the Ti−CH2Ph distances
Scheme 4. Migration of Benzyl Group from Group 4 Metal
to Pyridine Fragment: Known Examples
In our study the reaction of MBn4 with [ONO]-ligand
precursors 16, 17, and 19 resulted in 4-substituted amido
complexes (M = Ti) or complexes with 2-substituted amino
ligands containing an N−H fragment (M = Zr, Hf). It is
reasonable to expect that the first step in the reaction of MBn4
with the [ONO] ligands involves the formation of the tribenzyl
intermediates 25 after coordination of MBn4 and elimination of
a toluene molecule. Apparently in the case of M = Ti this is
followed by the formation of dibenzyl complex 26a as a
metastable intermediate, which further reacts to form the 4-
benzyl dihydroquinoline complex 20, apparently with the
participation of a second TiBn4 molecule, as proposed in
Scheme 5. In the case of Zr and Hf it is expected that the benzyl
transfer results in the formation of the intermediate 26b with a
dihydroquinoline amido ligand. Coordination of the second
hydroxyl group to the metal atom and proton transfer from the
C
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Scheme 5. Proposed Paths for the Formation of Ti and Zr/Hf [ONO] Dihydroquinoline Complexes
Table 1. DFT Total Energies (au) and Energies of 28 and 29 Relative to 27 (kcal/mol)
vary within 2.105−2.209 Å. The latter values are noticeably
greater than the distances we found in the structure of 20
(2.087(4) Å). It should be noted that Ti−benzyl bonding
seems to be very flexible. Thus, Cotton and coauthors20
reported the structure of the octahedral complex
Table 2. Selected Bond Lengths (Å) and Angles (deg) in 21,
22, and 20
21 (M = Zr)
22 (M = Hf)
20 (M = Ti)
M−O(1)
M−O(2)
M−N(1)
M−C(61)
M−C(71)
M−C(41)
M−C(42)
C(41)−C(42)
1.9611(14)
1.9400(14)
2.5359(17)
2.269(3)
1.9462(19)
1.924(2)
2.509(2)
2.251(3)
2.233(3)
1.819(3)
1.835(3)
1.903(3)
1
TiCl2(PhCH2)2(dmpe). According to H and 31P NMR data,
in benzene solution this compound exhibits two completely
equivalent benzyl ligands. Surprisingly, in the crystal form these
groups are tremendously different: Ti−CH2−CPh angles are
equal to 88.9(2) and 124.9(2)°.
Group 4 Metal Derivatives: Preparation of Type 10
Complexes. In an effort to accomplish the metalation of the
bis(hydroxyphenyl)quinolines with metal sources other than
MBn4, we explored the use of ZrCl4 in several alternative
procedures. Reaction of ZrCl4 with 16 in toluene with and
without a base (Et3N) did not result in the selective formation
of complexes; only gradual decomposition of the precursor was
observed. Deprotonation of 16 with NaH in THF and
treatment of the product with ZrCl4(THF)2 resulted in the
2.250(2)
2.087(4)
2.502(4)
1.469(6)
N(1)−M−C(61)
O(1)−M−O(2)
M−O(1)−C
M−O(2)−C
M−CH2−CPh
155.98(8)
125.98(6)
151.88(13)
148.83(13)
108.45(16)
116.85(15)
158.51(10)
126.07(8)
151.31(17)
148.53(18)
111.8(2)
136.70(12)
128.6(2)
133.2(2)
87.6(3)
116.8(2)
D
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Figure 1. Molecular structure of 21. Displacement ellipsoids are drawn at the 50% probability level. Hydrogen atoms (except amino H1) are omitted
for clarity.
Figure 2. Molecular structure of 20. Displacement ellipsoids are drawn at the 50% probability level. Hydrogen atoms are omitted for clarity. Two of
the four t-Bu groups are rotationally disordered over three positions.
formation of oligomeric products. We have also attempted
another approach successfully used earlier in metallocene
synthesis21 involving the reaction of LH2 with a 4-fold excess of
LiMe followed by treatment of the resulting mixture with ZrCl4.
Use of this method with ligands 16 and 19 resulted in the
formation of crystalline complexes LZrMe2(Et2O) 30 and 31
(Scheme 6), which do not lose the solvate ether molecule
indicates that the Et2O molecule is strongly coordinated to the
metal with no observed dissociation in solution. This
coordination leads to a significant shift of the Et2O signals in
the solvates: 0.44 and 0.48 ppm in C6D6 for the methyl groups
in 30 and 31 (vs 1.11 ppm of uncoordinated ether) and 2.57
and 2.68 ppm (vs 3.26 ppm) for the methylene group.
Ethylene/1-Butene Copolymerization. A series of ethyl-
ene copolymerization reactions were carried out with
1
during vacuum drying and gentle heating. A H NMR study
E
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Scheme 6. Preparation of [ONO] Quinoline Zr Alkyl
Complexes
complexes 20−24, 30, and 31, as well as the earlier reported
bis(phenoxy)pyridine complex 32 (Scheme 7),12b,c under
Figure 3. Ethylene consumption curve recorded in run 2 of Table 3.
Scheme 7. Benchmark Complexes for Polymer Test
stored before the test. In the case of complex 21 the catalyst
demonstrated retention of the initial performance in a
supported MAO/borate preactivated recipe for over 1 month.
The Zr complexes 21, 23, and 24 seem to show better overall
activity in comparison to complexes 30−32, where the pyridine
fragment remained intact after metalation.
The catalysts generated using the new complexes based on
the [ONO] quinolone template show a very high molecular
weight potential in copolymerization experiments without H2
(Table 3), with Mw values exceeding 500000 g/mol, where we
have been able to dissolve the samples for GPC tests. For
selected complexes we have evaluated the effect of hydrogen, a
common chain transfer agent, on the product properties (Table
4).
industrially relevant slurry polymerization conditions using
silica-supported recipes, preactivated with a mixed MAO/
borate cocatalyst, a system that was earlier reported by us to
result in active catalysts on combination with postmetallo-
cenes15 (Table 3).
Table 3. Ethylene/1-Butene Copolymerization Test in the
Absence of H2 using MAO/Trityl
Table 4. Ethylene/1-Butene Copolymerization Test in the
Presence of H2 (170 mmol) using MAO/Trityl
Tetrakis(pentafluorophenylborate) Activated Complexes
a
Tetrakis(pentafluorophenylborate) Activated Complexes
Supported on Silica
a
Supported on Silica
run
complex
A, kg/(mol h)
Mw, ×103
Mw/Mn
Br/1000
run
complex
A, kg/(mol h)
Mw, ×103
Mw/Mn
Br/1000
1
2
3
4
5
6
7
8
20
21
22
23
24
30
31
32
440
10903
556
1,405
12.7
b
7.6
9
21
23
32
7566
7826
4888
673
587
761
15.8
10.3
16.5
10.8
10.8
2.8
b
11.3
10
11
684
554
b
26.4
10.1
b
8900
6441
537
9.6
1.8
a
Catalysts and testing conditions are the same as those indicated in
Table 3.
b
b
1088
3682
b
b
b
b
2.7
All polymers produced with the new catalyst have a very
a
Polymerizations were carried out in a 2 L autoclave reactor with 3−8
broad molecular weight distribution (Tables 3 and 4),
indicating the presence of several active sites. The profiles of
MWDs for quinoline-based complexes 21 and 23 seem to be
quite different from what was observed from polymer samples
produced with the “Bercaw” complex under the same
conditions (Figure 4).
Interestingly, while the quinoline-based [CNN] complexes
demonstrate a very good Mw control with H2, as indicated by
the continuous drop of Mw of polymer samples with an increase
of H2 level in the reactor,15 the catalysts based on the new
complexes 21 and 23 show very little effect (compare run 10 vs
4, Tables 3 and 4; see Figure 5).
μmol of metal complex in 1 L of isobutane diluent at 15 bar partial
pressure of ethylene in the presence of 100 mL of 1-butene
comonomer and 1 mL of 1 M triisobutylaluminium scavenger at 70
°C. The supported catalyst was injected into an equilibrated reactor at
the polymerization temperature and the ethylene pressure maintained
throughout the 30−60 min long test. The silica-supported catalysts
were prepared by dissolving [Ph3C][B(C6F5)4] cocatalyst in a 4.21 M
MAO solution in toluene, followed by the complex (Al/B/metal 200/
1.1/1) and adding the resulting solution to a silica support calcined at
600 °C, resulting in a free-flowing powder, aged overnight before
b
testing. Polymer product was not soluble.
Under our testing conditions the Zr complexes seem to be
more active than their Ti and Hf analogues (complex 21 vs
complexes 20 and 22, respectively). The catalysts of this study
show very steep deactivation, as illustrated by the ethylene
consumption curves vs time (Figure 3), similarly to what was
observed for quinoline-based [CNN] complexes,15 in remark-
able contrast with the very good shelf life of catalyst samples
CONCLUSIONS
■
Quinoline-based [ONO]-type ligand precursors can be used to
prepare group 4 complexes of diverse structural types, where
the reactivity of the quinoline ring structure provides additional
“degrees of freedom” in designing new postmetallocene catalyst
systems. The new complexes of this study can be used as
F
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trichlorobenzene (TCB), and the temperature was 145 °C. The flow
rate was 1.0 mL/min.
Methoxymethyl derivatives 11−13 were prepared by sodium
phenolates with chloromethyl methyl ether in THF; MOM-protected
quinolines 14, 15, and 18 were prepared using Negishi coupling, and
deprotection to 16, 17, and 19 was performed by acid hydrolysis (for
details, see the Supporting Information).
[4-Benzyl-2,8-bis(3,5-di-tert-butyl-6-phenolato)-1,4-dihy-
dro-1-quinolyl]benzyltitanium (20). TiBn4 (0.91 g, 2.2 mmol) was
added at −20 °C to a well-stirred solution of 16 (1.08 g, 2 mmol) in a
mixture of toluene (15 mL) and hexane (15 mL). The resulting
solution was warmed to room temperature and stirred for 16 h.
Solvents were removed under reduced pressure, and hexane was
recondensed. The product was crystallized at −20 °C, separated by
decantation, washed with cold hexane, and dried in vacuo. The yield
was 0.59 g (39%). 1H NMR (C6D6, 20 °C): δ 7.55 (dd, J = 7.7 Hz, 1.3
Hz, 1H), 7.52 (d, J = 2.4 Hz, 1H), 7.48 (d, J = 2.4 Hz, 1H), 7.44 (d, J
= 7.3 Hz, 2H), 7.34 (d, J = 2.4 Hz, 1H), 7.28 (m, 3H), 7.20−6.99
(group m, 7H), 6.84 (d, J = 7.5 Hz, 1H), 5.65 (d, J = 6.2 Hz, 1H), 3.82
(m, 1H), 3.42 (d, J = 8.8 Hz, 1H), 3.00 (d, J = 8.0 Hz, 1H), 2.90 (d, J
= 8.8 Hz, 1H), 1.32 (s, 9H), 1.26 (s, 9H), 1.25 (s, 9H), 1.12 (s, 9H).
13C NMR (C6D6, 20 °C): δ 158.3, 156.8, 149.1, 143.92, 143.88, 143.4,
Figure 4. GPC traces of products generated in runs 9−11 (Table 4):
blue thick curve, run 9 (complex 21); green dotted curve, run 10
(complex 23); thin red curve, run 11 (complex 32).
140.14, 137.3, 135.3, 134.8, 132.8, 132.0, 131.5, 130.7, 130.0, 128.8,
128.64, 128.58, 128.52, 127.4, 127.1, 126.6, 126.5, 124.4, 123.9, 123.5,
108.9, 80.6, 43.9, 35.3, 35.1, 34.5, 34.44, 34.40, 31.7, 31.6, 30.8, 30.4,
22.7. Anal. Found: C, 79.57; H, 7.82; N, 1.88; O, 4.22. Calcd for
C51H59NO2Ti: C, 79.98; H, 7.76; N, 1.83; O, 4.18. Complexes 21−24
were prepared in the same manner (see the Supporting Information).
Dimethylzirconium 2,8-Bis(3,5-di-tert-butyl-6-phenolato)-
quinoline Diethyl Ether Complex (30). MeLi (1.6 M in ether, 3
mL, 4.8 mmol) was added at −20 °C to a well-stirred suspension of 16
(0.54 g, 1 mmol) in Et2O (20 mL). The mixture was warmed to room
temperature, cooled to −40 °C, and ZrCl4 (0.25 g, 1.1 mmol),
suspended in pentane (10 mL), was added. The mixture was warmed
to room temperature, the solution was separated by decantation, and
the precipitate of LiCl was washed with recondensed ether. The
solvent was partially removed (residual volume ∼5 mL), and the
product was obtained by crystallization at −20 °C, washed with cold
Figure 5. Effect of H2 in the reactor on the Mw value of copolymer (15
bar partial pressure of ethylene in the presence of 100 mL of 1-butene
comonomer at 70 °C; complexes activated with Al/(MAO)/
B(borate)/metal 200/1.1/1 and supported on 600 °C silica): blue
circles, complex 33 (Scheme 7), according to Figure 6 in ref 15; red
triangles, complex 21.
1
pentane, and dried in vacuo. The yield was 0.39 g (53%). H NMR
(C6D6, 20 °C): δ 7.75 (d, 3J = 8.5 Hz, 1H), 7.61 (m, 2H), 7.51 (dd, J =
3
4
8.5 Hz, 1.3 Hz, 1H), 7.49 (d, J = 8.5 Hz, 2H), 7.44 (d, J = 2.6 Hz,
1H), 7.35 (d, 3J = 8.2 Hz, 1H), 7.23 (m, 2H), 2.57 (broad, 4H,
−OCH2CH3), 1.70 (s, 9H), 1.67 (s, 9H), 1.35 (s, 9H), 1.32 (s, 9H),
0.44 (broad, 6H, −OCH2CH3), 0.33 (s, 6H). Anal. Found: C, 70.25;
H, 8.47; N, 1.99; O, 6.64. Calcd for C43H61NO3Zr: C, 70.64; H, 8.41;
N, 1.92; O, 6.56. Complex 31 was prepared in the same manner (see
the Supporting Information).
precursors to efficient polyolefin catalysts with unique perform-
ance, resulting in ethylene copolymers with very high molecular
weight, good comonomer incorporation, and multimodal
MWD.
EXPERIMENTAL SECTION
■
General Considerations. All operations with group IV metal
benzyl derivatives were performed under argon using standard Schlenk
techniques or under vacuum using a sealed glass “equipped-with-
everything” system. 2-tert-Butylphenol, 2,4-di-tert-butylphenol, 2-
phenylphenol, 2-bromoaniline, benzoylacetic ester, and MeLi (1.6 M
solution in ether) (Aldrich) and MAO solution in toluene (Albemarle)
were used as purchased. Sylopol 948 (Grace-Davison) was calcined at
600 °C before use. Toluene, ether, and THF were dried and distilled
over Na/benzophenone. Pentane and hexane were distilled over Na/K
ASSOCIATED CONTENT
■
S
* Supporting Information
Text, figures, tables, and CIF files giving experimental details
for the ligand precursor, group 4 metal complexes, and catalyst
preparation, polymerization procedures, and polymer analysis
and details of the crystal structure determination, atomic
coordinates, isotropic and anisotropic displacement parameters,
and bond lengths and angles for complexes 20−22. This
material is available free of charge via the Internet at http://
pubs.acs.org. Crystallographic data (excluding structure factors)
for the structures reported in this paper have also been
deposited with the Cambridge Crystallographic Data Centre as
supplementary publications no. CCDC 911881−911883.
Copies of the data can be obtained free of charge on
application to the CCDC, 12 Union Road, Cambridge CB2
1EZ, U.K. (fax, int.code +44(1223)336-033; e-mail, deposit@
ccdc.cam.ac.uk).
alloy. 2,8-Dibromoquinoline,14 tri-o-tolylphosphine,22 and Pd(dba)2
23
were prepared in accordance with published procedures. NMR spectra
were recorded on a Varian XR-400 (400 MHz) spectrometer and on a
Bruker spectrometer. Samples of group IV metal alkyl derivatives were
prepared by condensation of dried (over Na/benzophenone/dibenzo-
18-crown-6) and degassed deuterated solvents (C6D6 or toluene-d8)
into NMR tubes with 5−10 mg of the complexes. Elemental analysis
was performed on a Perkin-Elmer Series II CHNS/O Analyzer 2400
instrument. Polymer molecular weight and molecular weight
distributions were determined by GPC (gel permeation chromatog-
raphy). Measurements were conducted on a Waters GPCV-LS 2000
with three Polymer Lab Olexis columns. The solvent was
G
dx.doi.org/10.1021/om4001555 | Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
Patent Appl. EP 2093229, 2009. (e) Kirillov, E.; Roisnel, T.; Razavi, A.;
Carpentier, J.-F. Organometallics 2009, 28, 5036.
AUTHOR INFORMATION
Corresponding Author
*E-mail: inif@org.chem.msu.ru (I.E.N.); sandor.nagy@
lyondellbasell.com (S.M.N.).
■
(13) (a) Nagy, S.; Winslow, L. N.; Mihan, S.; Chevalier, R.; Lukesova,
L.; Nifant’ev, I. E.; Ivchenko, P. V.; Neal-Hawkins, K. L. (Equistar
Chem LP) US Patent Appl. US2011021344, 2011. (b) Nagy, S.;
Winslow, L. N.; Mihan, S.; Chevalier, R.; Lukesova, L.; Nifant’ev, I. E.;
Ivchenko, P. V. (Equistar Chem LP) US Patent Appl. US2011/
0021727, 2011.
Notes
The authors declare no competing financial interest.
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ACKNOWLEDGMENTS
■
We thank LyondellBasell for financial support and for
permission to publish this work.
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dx.doi.org/10.1021/om4001555 | Organometallics XXXX, XXX, XXX−XXX