Gas phase polymerization of ethylene with supported α-diimine Nickel(II) catalysts

Article abstract of DOI:10.1021/ma9025256

An efficient synthetic strategy for new 2,5- and 2,6-substituted unbridged and 1,4-dithiane bridged ligands is presented. The reaction of the latter compounds with Ni(acac)2 and trityl tetrakis(pentafluorophenyl)borate gave the corresponding Ni(II) complexes in high yields. The structure of one of these complexes was determined, by X-ray analysis. These complexes were supported on silica without a chemical tether and were used as catalysts for ethylene polymerization reactions in the gas phase. Furthermore, ethylene was polymerized with the unsupported 2, 5-complexes in homogeneous solution for comparison. The influence of the ligand structure, hydrogen and temperature on the polymerization performance was investigated. The supported catalysts showed moderate to high activities and produced polyethylenes ranging from HDPE to LLDPE, without further addition of an 1 -olefin comonomer. In contrast to 2,6complexes, which generate high molecular weight polyethylene, the 2,5-compounds afford materials of lower molecular weight comprising terminal and internal double bonds. In addition, video microscopy experiments allowed to investigate the growth of single polyethylene particles. Electron microscopy was applied to show that their morphology is a replicate of the starting catalyst grains.

Full text of DOI:10.1021/ma9025256

3624 Macromolecules 2010, 43, 3624–3633
DOI: 10.1021/ma9025256
Gas Phase Polymerization of Ethylene with Supported R-Diimine
Nickel(II) Catalysts
Marcus M. Wegner, Anna K. Ott, and Bernhard Rieger*
€
€
WACKER-Lehrstuhl fu€r Makromolekulare Chemie, Technische Universitat Munchen Lichtenbergstrasse 4,
D-85747 Garching, Germany
Received November 30, 2009; Revised Manuscript Received February 18, 2010
ABSTRACT: An efficient synthetic strategy for new 2,5- and 2,6-substituted unbridged and 1,4-dithiane
bridged ligands is presented. The reaction of the latter compounds with Ni(acac)2 and trityl tetrakis-
(pentafluorophenyl)borate gave the corresponding Ni(II) complexes in high yields. The structure of one of
these complexes was determined by X-ray analysis. These complexes were supported on silica without a
chemical tether and were used as catalysts for ethylene polymerization reactions in the gas phase. Further-
more, ethylene was polymerized with the unsupported 2,5-complexes in homogeneous solution for compa-
rison. The influence of the ligand structure, hydrogen and temperature on the polymerization performance
was investigated. The supported catalysts showed moderate to high activities and produced polyethylenes
ranging from HDPE to LLDPE, without further addition of an 1-olefin comonomer. In contrast to 2,6-
complexes, which generate high molecular weight polyethylene, the 2,5-compounds afford materials of lower
molecular weight comprising terminal and internal double bonds. In addition, video microscopy experiments
allowed to investigate the growth of single polyethylene particles. Electron microscopy was applied to show
that their morphology is a replicate of the starting catalyst grains.
Chart 1. r-Diimine Nickel(II) Complexes
Introduction
In the mid 1990s Brookhart introduced a new type of late
transition metal catalysts for the polymerization of ethylene.1
The R-diimine Ni(II) catalysts 1 and 1a (Chart 1) are able to
produce LLDPE-like ethylene homopolymers, which are com-
parable to polymers obtained by copolymerization of ethylene
and higher R-olefins.1,2
The reason for that are isomerization reactions of the growing
polymer chain end (chain walking).3 Despite their versatile
advantages, unfortunately, the activated catalysts 1 and 1a de-
activate rapidly in the presence of hydrogen. Recently, we repor-
ted on new polyaromatic, hydrogen-stable Ni(II) complexes,
such as 2a and 2b (Chart 1).4 In homogeneous solution poly-
merization they are highly active and ligand design allows a high
precision in control of the microstructure and therefore on the
properties of the resulting materials.
Most of the technical polyethylenes are produced in hetero-
geneous slurry or gas phase processes. To apply new single-site
catalysts under industrial conditions as “drop-in systems” they
have to be supported. Heterogenized catalysts should combine
the advantages of the classical heterogeneous catalysis, such as
good morphology, little reactor fouling, high powder density,
with the advantages of the homogeneous reaction, such as high
activity, control over the polymer microstructure and over
molecular weight distribution.5 Catalyst immobilization is still
a great challenge, since fractionation of the catalyst has to take
place in a controlled way in order to generate a homogeneous
product morphology. Silica is mainly used as support for single-
site catalysts due to its high surface area, good porosity and
mechanical properties.5,6 In literature various methods and carri-
ers are described to support nickel diimine complexes. Neutral
nickel complexes were supported on silica gel with and without
MAO pretreatment and were used in slurry and gas phase pro-
cesses.7 Brookhart reported on covalently anchored complexes
to enhance activity and prevent leaching from the surface.8
In contrast to metallocenes, R-diimine nickel catalysts can
directly be supported on silica gel without decomposition due to
the low oxophilicity of late transition metals. Silica-supported ionic
diimine nickel complexes for gas phase polymerization have been
reported by Eastman Chemical.9 A chemical linkage is not requi-
red for gas phase polymerization, since leaching of the catalyst
during the polymerization process in the gas phase is minimal or
not existing.10 Additionally, physically or chemically adsorbed
compounds have the advantage that the structure of the complex
has not to be changed by a linker and the original electronical and
structural properties are maintained on the carrier.
Videomicroscopy is a new andpowerful optical tool toobserve
the growth and fragmentation of polymer particles. A minireactor
*To whom all correspondence should be addressed. E-mail: rieger@
tum.de.
pubs.acs.org/Macromolecules
Published on Web 03/17/2010
r 2010 American Chemical Society

Article
Macromolecules, Vol. 43, No. 8, 2010 3625
Scheme 1. Synthesis of r-Diimine Nickel(II) Complexes
combined with a light microscope and a camera was first used for
investigations on the polymerization ofbutadienein the gas phase
by Reichert et al.11 Weickert and Fink et al. reported on poly-
merization with ethylene and propylene as well.12,13
Additionally, video and electron microscopy experiments allowed
a detailed insight into particle forming processes.
Results and Discussion
One major objective to support single-site catalysts is to repli-
cate the structure of the carrier into the morphology of the poly-
mer particles. Electron microscopy is an appropriate method to
characterize the structure and morphology of polymer particles.
Herein we present a synthetic route to 2,5- and 2,6-substituted
polyaromatic R-diimine Ni(II) catalysts based on 2,3-butane-
dione as well as 1,4-dithiane-bridged 2,6-catalysts. These new
compounds were directly supported on silica gel in order to
polymerize ethylene in the gas phase. For comparative studies
ethylene was polymerized using the unsupported 2,5-catalysts in
toluene as well. We describe the influences of ligand structure
and polymerization conditions on the polyethylene properties.
Ligand and Complex Synthesis. The new R-diimine ligands
based on 2,3-butanedione as well as the corresponding
nickel(II) complexes can be obtained in an easy four step
synthesis in very good yields (Scheme 1).4,14
The Grignard reaction with variably substituted bromo-
benzenes, followed by reaction with trimethylborate gave
boronic acids in excellent yields. The latter compounds were
converted to the corresponding terphenylamines 3a-d by
palladium-catalyzed Suzuki cross coupling reactions with
2,6-dibromoaniline and 2,5-dibromoaniline, respectively. The
third step involved the formation of polyaromatic diimi-
nes by acid-catalyzed condensation with 2,3-butanedione.

3626 Macromolecules, Vol. 43, No. 8, 2010
Wegner et al.
Table 1. Synthesized Precatalysts
complex
precatalyst
wt % Ni
8a
8a
8a
8b
9a
9a
9b
8c
8d
10a
1.0a
0.24
0.25a
1.0a
1.0a
0.27
1.0a
1.0a
1.0a
10a1
10a2
10b
11a
11a1
11b
10c
10d
a Theoretical maximum nickel loading.
was observed, which would cause a change in color or modify
the visual appearance. The amount of nickel was controlled
by weighting, elemental analysis and in selected cases by ICP.
The determined values are in the range of the theoretical
calculated loadings (Table 1).
Figure 1. Pov-Ray image of octamethyl complex 8c. Solvent molecules,
hydrogen atoms, and the counterion are omitted for clarity. The atoms
˚
are drawn as 50% thermal ellipsoids. Selected bond lengths [A]:
Gas Phase Polymerization. The gas phase polymerization
of ethylene was performed in a 450 mL steel autoclave in the
presence of sodium chloride. Additional to the gas phase
polymerization, ethylene was polymerized in toluene with
the unsupported 2,5-catalysts for comparison. The optimal
activator for polyaromatic R-diimine Ni(II) catalysts is
TMA, which gives in solution at a Al/Ni ratio of 500 the
highest activities.4 For polymerization in the gas phase an
increased aluminum concentration (Al/Ni = 1000) is requi-
red, since TMA can react with silanol groups on the surface.
In general, activity values of a catalyst deeply depend on reac-
tor type and reaction conditions as well as the considered
polymerization time. In order to get more reliable and
convincing results of activity the whole experiments were
carried out for 1 h. It is noteworthy that all catalysts were
active at 30 °C as well as 60 °C until the reaction was stopped.
Polymerization conditions and results are summarized in
Table 2.
Ni(1)-O(1) 1.819, Ni(1)-N(1) 1.887, N(1)-C(6) 1.281, N(2)-C(7)
1.290, C(6)-C(7) 1.492, N(1)-C(10) 1.441, and N(2)-C(32) 1.446.
Selected bond angles [deg]: O(1)-Ni(1)-O(2) 95.07, N(1)-Ni(1)-N(2)
82.34, C(7)-N(2)-Ni(1) 115.9, C(6)-N(1)-Ni(1) 116.2, C(10)-C-
(11)-C(16) 124.3, C(15)-C(14)-C(24) 121.4, C(32)-C(37)-C(46)
122.5, and C(33)-C(34)-C(38) 119.6.
Complexation of the diimine ligands 6a-d with the Ni(acac)2
precursor and the trityl salt of [B(C6F5)4]- led to red colored
complexes 8a-d in yields up to 85%.
A synthesis strategy to 1,4-dithiane-bridged diimines was
successfully developed by modifying and improving litera-
ture procedures (Scheme 1).9 First of all, oxalyl diamides
4a-b were obtained from the reaction of 2,6-terphenyl-
amines 3a-b with oxalyl chloride. The reaction of the two
chlorination agents PCl5 and SOCl2 with the oxalyl diamides
at higher temperatures finally afforded the yellow bis-imidoyl
chlorides 5a-b in yields above 80%. The desired 1,4-dithiane-
bridged diimines 7a-b were subsequently obtained by reaction
of bis-imidoyl chlorides 5a-b with 1,2-ethanedithiol. The
conversion to the Ni(II) complexes 9a-b is according to
8a-b reaching yields up to 92%.
A perfect particle forming process requires on the one
hand homogeneous temperature distribution and on the
other hand an uniform distribution of ethylene in the grow-
ing polymer particle.15 The unsupported 2,6-catalysts are
highly active in solution polymerization of ethylene which
release a lot of heat. It should be mentioned that in some
experiments at 30 °C temperature rose by 5 °C in the gas
phase, which could create hot spots leading to inhomogene-
ities and therefore to a decrease in activity. The 2,6-catalysts
exhibit the highest activities at 30 °C. 10b, 11a, and 11b show
their best performance in the presence of hydrogen. This is
not surprising and can be explained by more homogeneous
reaction conditions under hydrogen atmosphere. We pre-
viously reported on the same phenomena in solution poly-
Solid State Structure. In contrast to the highly symmetrical
2,6-R-diimine nickel(II) complexes, the 2,5-Ni(II) complexes
8c-d can show in general two structural isomers. In case of
1
8d there exists a mixture of two species. However, the H
NMR analysis of 8c shows, in contrast to 8d, only one
isomer. Suitable crystals for X-ray analysis were obtained
by slow condensation of pentane into the CH2Cl2 solution of
complex 8c at room temperature. The molecular structure of
complex 8c is illustrated in Figure 1.
The unit cell includes two complex molecules with coun-
terions and two molecules of methylene chloride. The X-ray
structure of 8c exhibits a C2 symmetry. Coordination around
the nickel center is distorted square planar, as expected.
The shift of one phenyl ring from the ortho to the meta
position opens the area around the nickel center, hence,
there is more space for an axial attack of a monomer and
of course probability of β-hydride elimination reactions
increases.
Heterogenization. The directly supported precatalysts
were prepared using a slightly modified procedure from
literature.9 The silica gel SP9-496 from Grace-Davison was
heated at 350 °C to remove all water from the surface. The
reduced oxophilicity and therefore greater functional group
tolerance of late transition metals allows heterogenization on
silica gel. The desired amount of complex and silica gel were
mixed in toluene. Removing the solvent led to red supported
precatalysts. Even after several months no decomposition
merization.14 The industrial interesting activity of 100 kgPE
/
gNi h and 1 kgPE/ghet cat, respectively, is achieved by 10a,
3
10b, and 11a. Elevated temperature (60 °C) results in an
activity decline. Because of higher polymerization tempera-
ture less ethylene adsorbs on the particle surface and pene-
trates through the particle to the active center. Furthermore,
heat removal from the particle must be considered as well.
The sterically less demanding tetramethyl-substituted cata-
lysts 10a and 11a show higher activities at 60 °C than the
octamethyl-substituted analogues.
10a1 and 11a1 with 0.24 wt % Ni and 0.27 wt % Ni,
respectively, exhibit slightly better activities at 60 °C than
the higher loaded Ni(II) catalysts. A higher amount of
nickel centers produce more heat which inhibits activity
by insufficient removal. Another explanation is that not
every nickel center is accessible for ethylene in case of the
higher loaded catalysts. Generally, activity of supported

Article
Macromolecules, Vol. 43, No. 8, 2010 3627
Table 2. Polymerization Results
sup. precat.b
[mg]
temp.
[°C]
X [m mmol
H2/ n mol C2H4]
yield
[g]
Mwc 10-3
[g/mol]
branches/
1000 Cd
Tm
[°C]
e
entry
cata
wt % Ni
gPE/ ghet cat kgPE/ gNi/h
PDIc
1
2
3
4
5
6
7
8
10a
10a
10a
10a
10a1
10a1
10a1
10a1
10b
10b
10b
10b
11a
11a
11a
11a
11a1
11a1
11a1
11a1
11b
11b
11b
11b
10c
1.0
1.0
1.0
1.0
0.24
0.24
0.24
0.24
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
0.27
0.27
0.27
0.27
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
7.0
8.5
9.5
7.9
18.9
19.6
19.3
20.5
7.4
8.2
8.9
7.2
7.7
7.6
6.7
6.4
30
30
60
60
30
30
60
60
30
30
60
60
30
30
60
60
30
30
60
60
30
30
60
60
30
30
60
60
30
30
60
60
0
1.92
0
1.92
0
1.92
0
1.92
0
1.92
0
1.92
0
1.92
0
1.92
0
1.92
0
1.92
0
1.92
0
1.92
0
3.84
0
3.84
0
3.84
0
9.5
9.9
7.2
2.8
5.8
4.8
4.4
1.9
6.5
10.9
2.5
1.0
3.1
8.1
3.5
2.5
5.2
7.3
6.5
4.1
2.1
3.9
3.1
2.2
1.6
2.2
4.9
5.8
0.5
0.4
1.1
0.4
1357
1165
758
354
307
245
228
93
136
117
76
35
127
101
94
38
88
133
28
14
40
107
52
39
69
79
77
47
25
49
20
21
18
27
55
83
5
2220
2300
2510
2460
3600
2240
3460
2910
2310
1990
2080
2440
2410
2690
2100
3700
3050
2810
2710
2060
2900
3820
2980
3420
80.60
86.90
34.10
35.80
36.20
53.40
11.40
11.80
1.7
1.7
2.0
1.9
1.6
1.9
1.7
2.0
1.8
1.8
2.1
2.2
1.8
1.8
1.8
1.9
1.7
1.9
1.7
1.9
2.1
1.6
2.0
1.7
3.6
2.9
4.4
3.4
2.1
4.1
3.2
2.9
8
8
12
12
7
126.7
126.8
120.2
121.7
128.4
128.7
117.6
119.9
124.1
126.8
116.1
116.5
125.2
126.0
117.7
118.5
125.0
125.3
117.7
118.2
126.7
123.3
107.2
111.9
129.6
132.5
119.9
120.8
128.8
129.7
117.3
116.8
8
13
12
9
9
878
1329
281
139
403
1066
522
391
186
215
210
128
250
494
201
210
184
265
551
829
49
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
9
14
16
7
8
16
14
8
28.0
34.0
31.0
32.0
8.4
8
16
15
9
7.9
8
15.4
10.5
8.7
8.3
8.9
7.0
10.3
8.9
18
16
18
17
22
30
10
15
31
28
10c
10c
10c
10d
10d
10d
10d
45
134
43
5
13
4
8.2
9.2
3.84
Solution Polymerizationf
33
34
35
36
37
38
39
40
8c
8c
8c
8c
8d
8d
8d
8d
7.4
7.4
7.4
7.4
16.0
16.0
16.0
16.0
30
30
60
60
30
30
60
60
0
3.84
0
3.84
0
3.84
0
88.7
302
201
134
199
137
139
80
14.10
14.40
3.50
3.20
8.10
7.85
2.60
2.57
3.3
2.3
2.1
2.3
2.8
2.9
2.4
2.4
6
20
25
23
8
10
31
29
133.0
130.4
111.8
111.7
125.3
126.3
107.1
107.6
58.8
39.2
58.4
80.4
81.3
46.8
41.9
3.84
71
a Cocatalyst: TMA. Al/Ni = 1000 (gas phase). Polymerization time: 1 h. Ethylene pressure: 10 bar. b For the solution polymerization the amount of
unsupported catalyst is mentioned. c Molecular weights and polydispersities are determined by GPC. d The branching degree was determined by 1H
NMR. e Melting points were determined by DSC. f Cocatalyst: TMA. Al/Ni = 500, 800 mL toluene. Polymerization time: 1 h. Ethylene pressure: 10 bar.
catalysts reaches a limiting value with increasing catalyst
loading.
The 2,5-catalysts show a different behavior of activity.
In the gas phase the highest activities are obtained at 60 °C,
but in solution the maxima of activity are achieved at 30 °C
(Figure 2).
It is suggested that different mass transport (ethylene)
and/or heat transfer limitations through the lower molecular
weight polyethylene produced by these catalysts (see below)
arise.
Unfortunately, heterogenization of the 2,5-complexes
leads to a decline in activity, which is a well-known effect
for supported single-site catalysts. However, 10c achieves a
remarkable activity of 83 kgPE/gNi h at 60 °C which is
3
slightly lower compared to 8c.
Figure 2. Activity values of 2,5-catalysts in the gas phase (10c, 10d) and
in solution (8c, 8d).
Surprisingly, activities of 8c, 8d in solution and 10c, 10d in
the gas phase remain constant or are actually higher in the
presence of hydrogen. Usually the activity drops in the
presence of hydrogen. A similar behavior was observed for
LFeCl2 systems.16 The mechanism as proposed by Zharakov
et al. is used to explain this hydrogen activation effect.17 The
ethylene polymers of 2,5-complexes have a broader mole-
cular weight distribution and a high percentage of terminal
vinyl groups (see below). A small amount of low molecular
weight products are produced and incorporated by 2,1-
insertion into the polymer chain, whereas dormant species
are formed. Hydrogen converts this species via chain transfer
reaction into a polymerization active hydride. Therefore, the

3628 Macromolecules, Vol. 43, No. 8, 2010
Wegner et al.
Figure 4. Melting temperature vs branches.
Figure 3. Molecular weights of the polyethylenes obtained by 2,5-cata-
lysts in the gas phase (10c, 10d) and in solution (8c, 8d).
of a ethylene molecule results in methyl-branched poly-
mer. A number of repeated isomerization reactions lead to
longer branched polymers. At ambient temperature (30 °C)
the branching degree of all polyethylenes obtained from the
2,6-catalysts is below 1% which results in almost linear
polyethylene. The ligand structure has no influence on the
degree of branching, but there is a small trend in melt-
ing points. At higher temperatures chain isomerization
becomes more favorable. Two main trends can be seen.
The more bulky the ligand the faster isomerization reac-
tions occur and therefore the extent of branching increases
whereas melting temperature declines. It seems that the
introduction of an additional backbone (11a) or a methyl-
group (10b) have a similar influence on polymer pro-
perties. The most sterical catalyst 11b exhibits the highest
branching degree and the lowest melting points, as expected
(Figure 4).
overall concentration of active sites is increased and hence
the activity rises.
All four 2,6-catalysts produce high molecular weight
polyethylenes with MW > 1 000 000 g/mol. No significant
influence of temperature and to our surprise hydrogen could
be detected. This is in contrast to published results of
homogeneous polymerization reactions.4 We would expect
lower molecular weights with an increasing amount of
hydrogen as we observed in homogeneous solution experi-
ments. It is suggested that only a lesser amount of hydrogen
is located at the active centers because of adsorption and
mass transport limitations. The polydispersity index of the
polyethylenes was around 2, which is typical for single-site-
compounds.
Compared to 2,6-complexes, 2,5-catalysts produce poly-
ethylene with lower molecular weight up to 100 000 g/mol
(Figure 3).
The 2,5-catalysts produce polyethylene with a branching
degree between 1 and 3%. The highest values are detected
at 60 °C. No significant influence of carrier as well as of
ligand structure on the isomerization behavior could be
This difference is attributed to the more open active center
due to shifting one phenyl ring from the ortho to the meta
position which is underlined by the crystal structure of 8c.
Chain termination happens more often compared to the
“close”-2,6 species. Thus, the resulting molecular weights
of the polyethylene are significantly reduced. Hydrogen has
no detectable influence on molecular weight in the gas phase
as well as in solution. However, ligand design affects mole-
cular weight of the polymers. The 3,5-substituted catalysts 8c
and 10c better prevent chain termination reaction and there-
fore produce polyethylenes with higher molecular weight
than in the case of 8d and 10d. Compared to solution
polymerization, notable higher molecular weight polymers
are produced by the 2,5-catalysts in the gas phase. The
increasing molecular weights lead to higher melting points
of the polymers in the gas phase. Similar results reported by
Janiak and Rieger with metallocenes and by Basset with
diimine nickel complexes.7d,18 The higher molecular weights
can be explained by reduced chain termination and/or higher
chain propagation. The surface of the carrier reduces the
space around the active center and might decrease chain
transfer rates as well. Furthermore, the elevated values may
be attributed to chain shuttling polymerization reactions on
the surface.19 The transfer of polymer chains from one
catalyst via trimethylaluminum to another active center
can also cause longer polymer chains. The 2,5-catalysts show
slightly higher unimodal molecular weight distributions
ranging between 2 and 4.
1
observed. These new polymers bear double bonds. The H
NMR spectra of polyethylenes produced by 2,5-catalysts re-
cord three additional peaks in the olefin region in agreement
with vinyl- and vinylen groups. Figure 5 shows a representative
spectrum.
The two signals 1 and 3 are assigned to the protons of a
vinyl end group. The broader peak at 5.4 ppm is attributed to
a vinylene fragment. Signal 4 belongs to methylene groups
next to a double bond.
Particle Morphology. The major objective of heterogeni-
zation is replication of support morphology into the final
polymer. Figure 6 depicts polymer particles from gas phase
polymerization.
The images in Figure 6 show spherical structures. How-
ever, sodium chloride affects the polymer morphology by
acting as an abrasive. Therefore, to gain information on the
growth and the formation of polymer particles without the
influence of sodium chloride, single particles of 10a2 were
analyzed by video microscopy. Figure 7 shows images after
different polymerization times.
All observed particles were active during the polymeriza-
tion, but there were differences in the growth of individual
grains. Without the grinding effect of sodium chloride the
structure and the morphology of polymer particles remained
a replicate of the starting catalyst particles.
The nickel diimine catalysts have the remarkable ability
to produce branched polyethylene from ethylene alone. A
β-hydride elimination generates a vinyl-terminated polymer
chain. Rotation around the double bond and 2,1-insertion
Electron microscopy studies of these structures were per-
formed to gain a deeper insight into structure formation. It is
obvious from Figure 8 that the porous structure of the silica
gel remains in the polymer particles as well.

Article
Macromolecules, Vol. 43, No. 8, 2010 3629
Figure 8. SEM images of polymer particles produced by 10a2.
Figure 5. Representative 1H NMR spectrum of the polyethylenes
obtained by 2,5-catalysts. Labels are discussed in the text.
Figure 9. SEM images of the cross-section of polymer particles.
Conclusion
New Ni(II) complexes bearing 2,5- (8c, 8d) as well as 2,6-
substituted (8a, 8b, 9a, 9b) diimine ligands are efficiently prepared
by an optimized and high yielding route. These complexes were
supported on silica gel and successfully used as a new catalyst
type to perform polymerization of ethylene in the gas phase under
various conditions. Additionally, ethylene was polymerized with
the unsupported 2,5-catalysts for comparison. Partially the
Figure 6. Representative polymer particles made by gas phase poly-
merization.
supported catalysts show high activities above 100 kgPE/gNi
h
3
and 1 kgPE/ghet cat, respectively. The 2,6-catalysts produce poly-
ethylenes with molecular weights over 106 g/mol whereas the 2,5-
catalysts generate lower molecular polymers below 100 000 g/mol.
Polyethylenes produced in the gas phase reveal higher molecular
weights than those from solution. The microstructure as well as
the melting behavior of the polyethylenes could be controlled and
tailor-made by ligand design. Moreover, vinyl and vinylene
groups were realized by using 2,5-catalysts. Video microscopy
experiments show that the polymers replicate the morphology of
the catalyst particles.
The polyaromatic R-diimine nickel(II) complexes have not yet
reached their full potential. Expecially the polyethylenes of the
2,5-catalysts are characterized by internal and terminal double
bonds. Therefore, the polymers can be chemically modified and
functionalized.
Experimental Section
General Procedures. All air- and moisture-sensitive adjust-
ments were carried out under dry argon atmosphere, using
conventional Schlenk techniques. For purification, methylene
chloride was distilled from CaH2, n-pentane from sodium and
toluene from LiAlH4. Pyridine was dried over activated alumi-
num oxide. Diacetylacetonatonickel(II), phosphorus penta-
chloride, thionyl chloride, sodium chloride, 2,5- and 2,6-dibro-
moaniline were purchased from Merck and ABCR and used as
received. Ethylene (Linde, grade 3.0) and hydrogen (Linde,
grade 5.0) were used without further purification. Silica gel
SP9-496 was supplied by Grace Davison. The synthesized
Figure 7. Snapshots of catalyst 10a2 and growing polymer particles
after (a) 0, (b) 20, (c) 40, (d) 60, (e) 90, and (f) 120 min at 60 °C and 4 bar
ethylene pressure.
1
compounds were characterized by H- and 13C NMR analysis
The cauliflower-like morphology consists of subparticles
which are held together by polymer fibers. The polymer
particles are not a compact material. The inside consists of
pores which allow diffusion of ethylene to the active centers
(Figure 9).
on a Bruker DRX 400 and on a Bruker ARX-300 spectrometer.
Chemical shifts δ are given in ppm in reference to 1H NMR and
13C NMR signals of the deuterated solvents. MALDI-TOF and
CI mass-spectra were recorded on Bruker Daltonics REFLEX
III and Finnigan MAT TSQ-7000 mass spectrometers in the

3630 Macromolecules, Vol. 43, No. 8, 2010
Wegner et al.
Department of Mass Spectrometry, University of Ulm and on
Bruker Biflex III (MALDI-TOF) in the Microanalytical Depart-
€
ment of Inorganic Chemistry, TU Munchen. Elemental analyses
(C, H, N) of the compounds were determined in the Micro-
H
arom), 7.05 (ds, 1H, Harom), 3.96 (s, 2H, NH2), 2.47 (s, 6H, CH3),
2.46 (s, 6H, CH3). 13C NMR (100.16 MHz, C2D2Cl4, 298 K) δ:
143.73, 141.20, 140.88, 139.14, 138.48, 138.27, 130.85, 129.06,
128.93, 126.86, 126.82, 125.02, 117.65, 114.26, 21.60, 21.55. Anal.
Calcd for C22H23N: C, 87.66; H, 7.69; N, 4.65. Found: C, 87.50; H,
7.67; N, 4.62.
€
analytical Laboratory of the University of Ulm, TU Munchen
and outside the university. The ICP analysis was performed
outside the university. The X-ray diffraction measurement was
performed at the University of Ulm on a Rigaku AFC7S
diffractometer. [Pd(PPh3)4], trityl tetrakis(pentafluorophenyl)-
borate and the different boronic acids were prepared according
to published literature procedures.
4,400-Di-tert-butyl-1,10;40,100-terphenyl-20-ylamine (3d). 4-t-
Butylphenylboronic acid (27.0 g, 151.7 mmol), 2,5-dibromoani-
line (14.6 g, 58.2 mmol), [Pd(PPh3)4] (8.1 g, 7.0 mmol), Na2CO3
(41.6 g, 392.5 mmol); white solid; yield: 14.1 g (68%). 1H NMR
(400.13 MHz, C2D2Cl4, 298 K) δ: 7.60 (d, 2H, Harom), 7.46-7.52
(q, 6H, Harom), 7.24 (d, 1H, Harom), 7.11 (dd, 1H, Harom), 7.03
(ds, 1H, Harom), 3.92 (s, 2H, NH2), 1.41 (s, 9H, CH3), 1.40 (s, 9H,
CH3). 13C NMR (100.16 MHz, C2D2Cl4, 298 K) δ: 150.36,
150.10, 143.89, 140.71, 137.63, 136.01, 130.99, 128.66, 126.56,
126.46, 125.86, 125.78, 117.45, 113.99, 34.60, 34.55, 31.50. Anal.
Calcd for C26H31N: C, 87.34; H, 8.74; N, 3.92. Found: C, 87.22;
H, 8.59; N, 3.90.
General Procedure for Synthesis of the r-Diimines Based on
2,3-Butanedione. The diimines were prepared according to
literature procedures.4,14 In a 250 mL Schlenk flask the terphe-
nylamine (2.2 equiv) and a catalytic amount of p-toluenesulfonic
acid monohydrate (0.06 equiv) were dissolved in benzene (150 mL).
2,3-Butanedione (1 equiv) was added at once and a Dean-Stark
apparatus attached. After refluxing the mixture for 48 h (2,5-
terphenylamines) and 72 h (2,6-terphenylamines), respectively,
the solvent was evaporated in vacuo. The crude product was
taken up in methylene chloride followed by addition of metha-
nol. The resultant yellow precipitate was filtered off and the
precipitation procedure repeated two more times. The pure pro-
duct was dried in vacuo to give a fine yellow powder.
The polymers were analyzed by NMR spectroscopy in bro-
mobenzene-d5 and p-xylene-d6 at 363 K by using a Bruker
AMX-500 spectrometer. The amount of branches was deter-
1
mined by H NMR spectroscopy. Molecular weights and dis-
tributions were measured using a Waters Alliance GPC 2000
system (145 °C, 1,2,4-trichlorobenzene) relative to polystyrene
standards. Melting points were determined by differential scan-
ning calorimetry (DSC). The melting curves were recorded on a
Perkin-Elmer DCS-7. Scanning electron microscopy images
were taken on a Hitachi Tabeltop Microscope TM-1000. Gas
phase polymerization experiments were performed in a 450 mL
and solution polymerization in 2 L Parr autoclave. Ethylene and
hydrogen were constantly fed to the reactor at constant pres-
sure. Gas flows were recorded with the software Genie V 3.0.
Addition of hydrogen was controlled by a master-slave setup.
General Procedure for Synthesis of the Terphenylamines. The
terphenylamines were synthesized by previously reported litera-
ture procedures.4,14 In a 1 L Schlenk flask dibromoaniline
(1 equiv), [Pd(PPh3)4] (12 mol %), 2 M Na2CO3 solution (6.75
equiv) were dissolved in benzene (400 mL). Solution of an
arylboronic acid (2.6 equiv) in ethanol (50 mL) was added and
stirred under reflux for 48 h (2,5-terphenylamines) and 72 h (2,6-
terphenylamines), respectively. The organic phase was sepa-
rated and the aqueous phase was extracted with benzene. The
combined organic phases were treated with hydrochloric acid
(25 mL). The solvent was removed and the residue was sus-
pended with diethyl ether. Saturated Na2CO3-solution was
added and the mixture was stirred for 10 min. The organic
phase was separated and the aqueous phase was extracted with
diethyl ether. The organic solvent was removed in vacuo. The
crude product was recrystallized from methanol to give pure
white terphenylamines.
ArNdC(CH3)-C(CH3)dNAr (6a, Ar = 2,6-(3-(CH3)C6H4)2-
C6H3). Terphenylamine 3a (4.5 g, 16.5 mmol), 2,3-butanedione
(646 mg, 7.5 mmol), p-TosOH H2O (86 mg, 0.45 mmol); yellow
3
solid; yield: 3.6 g (80%). 1H NMR (400.13 MHz, C2D2Cl4, 298 K)
δ: 7.30 (d, 4H, Harom), 7.21 (t, 2H, Harom), 7.14 (s, 4H, Harom),
7.00-7.06 (m, 12H, Harom), 2.20 (s, 12H, CH3), 1.46 (s, 6H,
CH3). 13C NMR (100.16 MHz, C2D2Cl4, 298 K) δ: 166.29,
146.43, 139.49, 136.94, 130.93, 129.88, 129.39, 127.75, 127.72,
125.95, 124.24, 21.47, 16.01. Anal. Calcd for C44H40N2: C,
88.55; H, 6.76; N, 4.69. Found: C, 88.41; H, 6.74; N, 4.64.
ArNdC(CH3)-C(CH3)dNAr (6b, Ar=2,6-(3,4-(CH3)2C6H3)2-
C6H3). Terphenylamine 3b (6.0 g, 19.9 mmol), 2,3-butanedione
3,300-Dimethyl-1,10;30,100-terphenyl-20-ylamine (3a). 3-Methyl-
phenylboronic acid (28.9 g, 212.6 mmol); 2,6-dibromoaniline
(20.5 g; 81.7 mmol); [Pd(PPh3)4] (11.3 g, 9.8 mmol); Na2CO3
(58.5 g, 551.5 mmol); white solid; yield: 18.1 g (81%). 1H NMR
(400.13 MHz, C2D2Cl4, 298 K) δ: 7.47-7.49 (m, 6H, Harom),
7.31 (d, 2H, Harom), 7.26 (d, 2H, Harom), 7.00 (t, 1H, Harom), 4.02
(s, 2H, NH2), 2.55 (s, 6H, CH3). 13C NMR (100.16 MHz,
C2D2Cl4, 298 K) δ: 140.89, 139.81, 138.57, 130.10, 129.73, 128.84,
128.08, 127.92, 126.36, 118.4, 21.67. Anal. Calcd for C20H19N:
C, 87.87; H, 7.01; N 5.12. Found: C, 87.71; H, 6.99; N, 5.07.
3,4,300,400-Tetramethyl-1,10;30,100-terphenyl-20-ylamine (3b). 3,4-
Dimethylphenylboronic acid (34.7 g, 231.3 mmol), 2,6-dibromo-
aniline (22.3 g, 88.9 mmol), [Pd(PPh3)4] (13.8 g, 11.9 mmol),
Na2CO3 (63.6 g, 600.1 mmol); white solid; yield: 16.5 g (62%).
1H NMR (400.13 MHz, C2D2Cl4, 298 K) δ: 7.52 (s, 2H, Harom),
7.48 (d, 2H, Harom), 7.42 (d, 2H, Harom), 7.32 (d, 2H, Harom), 7.04
(t, 1H, Harom), 4.12 (s, 2H, NH2), 2.53 (s, 6H, CH2), 2.52 (s, 6H,
CH3). 13C NMR (100.16 MHz, C2D2Cl4, 298 K) δ: 141.01, 137.43,
137.09, 135.51, 130.58, 130.19, 129.60, 127.91, 126.71, 118.13,
19.97, 19.63. Anal. Calcd for C22H23N: C, 87.66; H, 7.69; N,
4.65. Found: C, 87.61; H, 7.67; N, 4.68.
(779 mg, 9.0 mmol), p-TosOH H2O (103 mg, 0.54 mmol);
3
yellow solid; yield: 2.8 g (47%). 1H NMR (400.13 MHz,
C2D2Cl4, 298 K) δ: 7.31 (d, 4H, Harom), 7.21 (t, 2H, Harom),
7.17 (s, 4H, Harom), 6.91 (s, 8H, Harom), 2.32 (s, 12H, CH3),), 2.21
(s, 12H, CH3), 1.55 (s, 6H, CH3). 13C NMR (100.16 MHz,
C2D2Cl4, 298 K) δ: 167.47, 145.95, 137.46, 135.86, 134.66,
131.23, 130.51, 129.04, 128.50, 126.41, 124.15, 19.74, 16.85.
Anal. Calcd for C48H48N2: C, 88.30; H, 7.41; N, 4.29. Found:
C, 88.24; H, 7.40; N, 4.27.
ArNdC(CH3)-C(CH3)dNAr (6c, Ar=2,5-(3,5-(CH3)2C6H3)2-
C6H3). Terphenylamine 3c (5.1 g, 16.9 mmol), 2,3-butanedione
(662 mg, 7.7 mmol), p-TosOH H2O (88 mg, 0.46 mmol); yellow
3
solid; yield: 4.1 g (82%). 1H NMR (400.13 MHz, C2D2Cl4, 298
K) δ: 7.50 (d, 2H, Harom), 7.44 (dd, 2H, Harom), 7.32 (s, 4H,
H
arom), 7.06 (br. s, 6H, Harom), 6.99 (ds, 2H, Harom), 6.90 (s, 2H,
H
arom), 2.43 (s, 12H, CH3), 2.26 (s, 12H, CH3), 1.92 (s, 6H,
CH3). 13C NMR (100.16 MHz, C2D2Cl4, 298 K) δ: 167.86,
148.84, 140.53, 140.28, 138.81, 138.47, 138.24, 130.66, 129.97,
128.60, 128.49, 127.00, 124.98, 122.99, 117.01, 21.63, 21.42,
16.23. Anal. Calcd for C48H48N2: C, 88.30; H, 7.41; N, 4.29.
Found: C, 88.13; H, 7.32; N, 4.22.
3,5,300,500-Tetramethyl-1,10;40,100-terphenyl-20-ylamine (3c). 3,5-
Dimethylphenylboronic acid (25.0 g, 166.7 mmol), 2,5-dibromo-
aniline (16.1 g, 64.2 mmol), [Pd(PPh3)4] (8.9 g, 7.7 mmol), Na2CO3
ArNdC(CH3)-C(CH3)dNAr (6d, Ar = 2,5-(4-(C(CH3)3)-
C6H4)2C6H3). Terphenylamine 3d (4.6 g, 12.9 mmol), 2,3-buta-
nedione (504 mg, 5.9 mmol), p-TosOH H2O (67 mg, 0.35
3
1
(45.9 g, 433.1 mmol); white solid; yield: 16.3 g (84%). H NMR
(400.13 MHz, C2D2Cl4, 298 K) δ: 7.32 (s, 2H, Harom), 7.27 (d, 1H,
mmol); yellow solid; yield: 3.1 g (69%). 1H NMR (400.13 MHz,
C2D2Cl4, 298 K) δ: 7.63 (d, 4H, Harom), 7.49-7.54 (m, 8H,
Harom), 7.36 (br. s, 8H, Harom), 6.96 (ds, 2H, Harom), 2.01 (s, 6H,
Harom), 7.20 (s, 2H, Harom), 7.13 (dd, 1H, Harom), 7.08 (s, 2H,

Article
Macromolecules, Vol. 43, No. 8, 2010 3631
CH3), 1.40 (s, 18H, CH3), 1.36 (s, 18H, CH3). 13C NMR (100.16
MHz, C2D2Cl4, 298 K) δ: 168.35, 150.70, 149.89, 148.64, 140.08,
137.18, 135.99, 130.68, 130.22, 128.92, 126.62, 125.94, 124.84,
122.88, 117.07, 34.59, 34.54, 31.50, 16.54. Anal. Calcd for
C56H64N2: C, 87.91; H, 8.43; N, 3.66. Found: C, 87.75; H,
8.36; N, 3.66.
extracted with methylene chloride. The solvent was removed in
vacuo. The crude product was taken up in methylene chloride
followed by addition of methanol. The resultant yellow pre-
cipitate was filtered off and the precipitation procedure repeated
two more times. The pure product was dried in vacuo to give a
fine yellow powder.
General Procedure for Synthesis of the Oxalyl Diamides. The
desired terphenylamine (2.1 equiv) was dissolved in dry pyridine
(40 mL) in a Schlenk flask and the stirred solution was treated
under argon atmosphere dropwise with oxalyl chloride (1 equiv)
at 0 °C. After the addition was finished the cooling was aban-
doned and the reaction mixture was allowed to stir for 12 h.
Water was added and the solution was extracted with methylene
chloride. The solvent was removed in vacuo and the crude
product recrystallized from isopropanol to give a pure white
oxalyl diamide product.
ArNdC(S(CH2)2S)CdNAr (7a, Ar = 2,6-(3-(CH3)C6H4)2-
C6H3). Bis(imidoyl) chloride 5a (2.0 g, 3.1 mmol), 1,2-ethane-
dithiol (1.48 g, 15.7 mmol), and NaH (377 mg, 15.7 mmol) were
used; yellow solid; yield: 1.25 g (60%). 1H NMR (400.13 MHz,
C2D2Cl4, 298 K) δ: 7.44 (d, 4H, Harom), 7.28 - 7.35 (m, 10H,
Harom), 7.20 (t, 4H, Harom), 7.08 (d, 4H, Harom), 2.26 (s, 12H,
Harom), 2.01 (s, 4H, CH2). 13C NMR (100.16 MHz, C2D2Cl4,
298 K) δ: 153.91, 144.94, 139.02, 137.01, 131.23, 130.55, 129.26,
127.73, 127.48, 126.76, 124.97, 30.39, 21.51. Anal. Calcd for
C44H38N2S2: C, 80.20; H, 5.81; N, 4.25. Found: C, 80.05; H,
5.80; N, 4.20. Mass spectrum (CI): m/z: 659 ([MHþ], 100).
ArNdC(S(CH2)2S)CdNAr (7b, Ar = 2,6-(3,4-(CH3)2C6H3)2-
C6H3). Bis(imidoyl) chloride 5b (2.1 g, 3.0 mmol), 1,2-ethane-
dithiol (1.43 g, 15.2 mmol), and NaH (364 mg, 15.2 mmol) were
ArNC(O)-C(O)NAr (4a, Ar = 2,6-(3-(CH3)C6H4)2C6H3).
Terphenylamine 3a (3.2 g, 11.7 mmol), oxalyl chloride (0.70 g,
5.5 mmol); white solid; yield: 2.2 g (67%). H NMR (400.13
1
MHz, C2D2Cl4, 298 K) δ: 8.48 (s, 2H, NH), 7.46 (t, 2H, Harom),
7.38 (d, 4H, Harom), 7.19-7.25 (m, 8H, Harom), 7.16 (s, 4H,
Harom), 7.06 (d, 4H, Harom), 2.40 (s, 12H, CH3). 13C NMR
(100.16 MHz, C2D2Cl4, 298 K) δ: 157.32, 139.75, 138.89, 138.04,
129.96, 129.45, 129.33, 128.29, 128.9, 127.94, 125.34, 21.64.
Anal. Calcd for C42H36N2O2: C, 83.97; H, 6.04; N, 4.66. Found:
C, 83.74; H, 6.18; N, 4.55.
1
used; yellow solid; yield: 0.9 g (42%). H NMR (400.13 MHz,
C2D2Cl4, 298 K) δ: 7.40 (d, 4H, Harom), 7.26-7.30 (m, 6H, Harom),
7.21(d, 4H, Harom), 7.03(d, 4H, Harom), 2.25(s, 12H, CH3), 2.13(s,
12H, CH3), 1.99 (s, 4H, CH2). 13C NMR (100.16 MHz, C2D2Cl4,
298 K) δ: 153.87, 145.00, 136.73, 135.59, 134.83, 131.12, 131.04,
129.07, 128.97, 127.10, 124.85, 30.20, 19.60, 19.56. Anal. Calcd for
C48H46N2S2: C, 80.63; H, 6.48; N, 3.92. Found: C, 80.49; H, 6.43;
N, 3.88. Mass spectrum (CI): m/z: 715 ([MHþ], 100).
General Procedure for Synthesis of the Nickel(II) Complexes.
A procedure reported previously was used to synthesize the
nickel(II) complexes.4,14 In a 100 mL Schlenk flask, the diimine
(1 equiv) and Ni(acac)2 (1 equiv) were placed and dissolved in
methylene chloride (50 mL). [CPh3][B(C6F5)4] (1 equiv) in
methylene choride (15 mL) was added slowly using a syringe.
The resultant dark-red solution was stirred overnight. The
solution was filtered through an alumina column, using methy-
lene chloride as eluent. The volume was reduced to 15 mL and
n-pentane was added slowly to precipitate the complex. The
slightly colored supernatant was decanted and the precipitate
was dissolved in methylene chloride (15 mL). The procedure was
repeated four times. The pure product was dried in vacuo to
yield a red powder.
ArNC(O)-C(O)NAr (4b, Ar=2,6-(3,4-(CH3)2C6H3)2C6H3).
Terphenylamine 3b (5.2 g, 17.3 mmol), oxalyl chloride (1.05 g,
8.3 mmol); white solid; yield: 3.5 g (64%). H NMR (400.13
1
MHz, C2D2Cl4, 298 K) δ: 8.51 (s, 2H, NH), 7.42 (t, 2H, Harom),
7.35 (d, 4H, Harom), 7.13 (s, 4H, Harom), 7.05 (d, 4H; Harom), 6.98
(d, 4H, Harom), 2.33 (s, 12 H, CH3), 2.29 (s, 12H, CH3). 13C
NMR (100.16 MHz, C2D2Cl4, 298 K) δ: 157.60, 139.46, 136.74,
136.57, 135.71, 130.07, 129.92, 129.39, 129.30, 127.85, 125.59,
19.93, 19.74. Anal. Calcd for C46H44N2O2: C, 84.11; H, 6.75; N,
4.26. Found: C, 83.14; H, 6.77; N, 4.21.
General Procedure for Synthesis of the Bis(imidoyl) Chlorides.
The oxalyl diamide (1 equiv), PCl5 (2 equiv), and SOCl2 (4 equiv)
were solved in dry toluene (30 mL) and heated 1 h at 60 °C. The
reactions mixture was cooled down to room temperature and
pentane was slowly added to the stirred solution resulting in
product precipitation. The precipitate was separated, washed
with pentane and dried in vacuo. The product was isolated as a
yellow powder.
ArNdC(Cl)-C(Cl)dNAr (5a, Ar=2,6-(3-(CH3)C6H4)2C6H3).
Oxalyl diamide 4a (3.5 g, 5.8 mmol), PCl5 (2.4 g, 11.5 mmol), and
SOCl2 (2.8 g, 23.5 mmol) were used; yellow solid; yield: 3.0 g
(81%). 1H NMR (400.13 MHz, C2D2Cl4, 298 K) δ: 7.32-7.40
(m, 6H, Harom), 7.05-7.15 (m, 16H, Harom), 2.21 (s, 12H,
CH3).13C NMR (100.16 MHz, C2D2Cl4, 298 K) δ: 142.11,
138.31,137.41, 137.30, 131.38, 129.82, 129.40, 128.22, 127.98,
126.05, 125.91, 21.44. Anal. Calcd for C42H34Cl2N2: C, 79.11;
H, 5.37; N, 4.39. Found: C, 78.88; H, 5.47; N, 4.34.
ArNdC(Cl)-C(Cl)dNAr (5b, Ar = 2,6-(3,4-(CH3)2C6H3)2-
C6H3). Oxalyl diamide 4b (2.3 g, 3.50 mmol), PCl5 (1.5 g, 7.2
mmol), and SOCl2 (1.6 g, 13.45 mmol) were used; yellow solid;
yield: 2.07 g (85%). 1H NMR (400.13 MHz, C2D2Cl4, 298 K) δ:
7.31-7.40 (m, 6H, Harom), 7.13 (s, 4H, Harom), 6.96-7.02 (m,
8H, Harom), 2.29 (s, 12H, Harom), 2.18 (s, 12H, Harom). 13C NMR
(100.16 MHz, C2D2Cl4, 298 K) δ: 141.58, 137.59, 136.22, 136.13,
135.34, 131.76, 130.53, 129.40, 129.31, 126.33, 125.99, 19.73,
19.71. Anal. Calcd for C46H42Cl2N2: C, 79.64; H, 6.10; N, 4.04.
Found: C, 79.52; H, 6.07; N, 3.88.
[(ArNdC(CH3)-C(CH3)dNAr)Ni(acac)]B(C6F5)4 (8a, Ar=
2,6-(3-(CH3)C6H4)2C6H3). Diimine 6a (1.34 g, 2.24 mmol),
Ni(acac)2 (577 mg, 2.24 mmol), and [CPh3][B(C6F5)4] (2.1 g,
1
2.28 mmol) were used; red solid, yield: 2.7 g (84%). H NMR
(400.13 MHz, C2D2Cl4, 298 K) δ: 7.50 (t, 2H, Harom), 7.28-7.32
(m, 12H, Harom), 7.09 (s, 4H, Harom), 7.02 (d, 4H, Harom), 5.41 (s,
1H, CH), 2.37 (s, 12H, CH3), 1.61 (s, 6H, CH3), 1.43 (s, 6H,
CH3). Anal. Calcd for C73H47BF20N2NiO2: C, 61.16; H, 3.30;
N, 1.95. Found: C, 61.29; H, 3.35; N, 1.85. Mass spectrum
(MALDI): m/z: 753.1 ([Mþ -borate], 100).
[(ArNdC(CH3)--C(CH3)dNAr)Ni(acac)]B(C6F5)4 (8b, Ar =
2,6-(3,4-(CH3)2C6H3)2C6H3). Diimine 6b (1.0 g, 1.53 mmol),
Ni(acac)2 (394 mg, 1.53 mmol), and [CPh3][B(C6F5)4] (1.41 g,
1.53 mmol) were used; red solid; yield: 1.95 g (85%). 1H NMR
(400.13 MHz, C2D2Cl4, 298 K) δ: 7.50 (t, 2H, Harom), 7.31 (d,
4H, Harom), 7.15 (d, 4H, Harom), 7.11 (s, 4 H, Harom), 7.06 (d, 4 H,
H
arom), 5.30 (s, 1H, CH), 2.36 (s, 12H, Harom), 2.27 (s, 12H,
CH3), 1.55 (s, 6H, CH3), 1.40 (s, 6H, CH3). Anal. Calcd for
C77H55BF20N2NiO2: C, 62.08; H, 3.72; N, 1.88. Found: C,
62.03; H, 3.78; N, 1.86. Mass spectrum (MALDI): m/z: 809.5
([Mþ -borate], 100).
General Procedure for Synthesis of the 1,4-Dithiane-Bridged
Diimines. 1,2-Ethanedithiol (5 equiv) was slowly added to a stir-
red solution of NaH (5 equiv) in dry THF (100 mL) at 0 °C.
Cooling was abandoned and the reaction mixture was allowed
to stir at room temperature for 2 h. Then bis(imidoyl) chloride
(1 equiv) in dry THF (20 mL) was slowly added. The yellow
solution was heated under reflux for 48 h. Water was added and
[(ArNdC(CH3)-C(CH3)dNAr)Ni(acac)]B(C6F5)4 (8c, Ar =
2,5-(3,5-(CH3)2C6H3)2C6H3). Diimine 6c (1.3 g, 1.99 mmol),
Ni(acac)2 (512 mg, 1.99 mmol), and [CPh3][B(C6F5)4] (1.84 g,
1.99 mmol) were used; red solid; yield: 2.5 g (84%). H NMR
(400.13 MHz, C2D2Cl4, 298 K) δ: 7.78 (d, 2H, Harom), 7.66 (s,
4H, Harom), 7.54 (d, 2H, Harom), 7.25 (s, 4H, Harom), 7.18 (s, 2H,
1
H
arom), 7.14 (s, 4H, Harom), 5.50 (s, 1H, CH), 2.53 (s, 12H, CH3),

3632 Macromolecules, Vol. 43, No. 8, 2010
Wegner et al.
2.46 (s, 12H, CH3), 1.75 (s, 6H, CH3), 1.65 (s, 6H, CH3). Anal.
Calcd for C77H55BF20N2NiO2: C, 62.08; H, 3.72; N, 1.88.
Found: C, 61.94; H, 3.68; N, 1.86. Mass spectrum (MALDI):
m/z: 809.5 ([Mþ -borate], 100).
loading: 1 wt %. Anal. Calcd for 1 wt % Ni: C, 14.95. Found: C,
14.56 (0,97 wt % Ni).
11a1 (0.27 wt % Ni). Silica gel (320 mg), complex 9a (109.0 mg),
and methylene chloride (7 mL) were used. Theoretical nickel
loading: 1 wt %. Anal. Calcd for 1 wt % Ni: C, 14.95. Found: C,
3.98 (0.27 wt % Ni).
11b (1 wt % Ni). Silica gel (300 mg), complex 9b (107.7 mg),
and methylene chloride (7 mL) were used. Theoretical nickel
loading: 1 wt %. Anal. Calcd for 1 wt % Ni: C, 15.76. Found: C,
16.19 (1.03 wt % Ni).
[(ArNdC(CH3)-C(CH3)dNAr)Ni(acac)]B(C6F5)4 (8d, Ar=
2,5-(4-(C(CH3)3)C6H4)2C6H3). Diimine 6d (1.2 g, 1.57 mmol),
Ni(acac)2 (403 mg, 1.57 mmol), and [CPh3][B(C6F5)4] (1.45 g,
1.57 mmol) were used; red solid; yield: 1.95 g (78%). There are
existing two isomers. Isomer 1: 64%. Isomer 2: 36%. 1H NMR
(400.13 MHz, C2D2Cl4, 298 K) δ: 7.71-7.77 (m, 10H, Harom),
7.54-7.60 (m, 12 H, Harom), 5.43 (s, 1H, CH, isomer 1), 5.36 (s,
1H, CH, isomer 2), 1.95 (s, 6H, CH3, isomer 1), 1.81 (s, 6H, CH3,
isomer 2), 1.59 (s, 6H, CH3, isomer 1), 1.55 (s, 6H, CH3, isomer 2),
1.37-1.41 (m, 36H, CH3). Anal. Calcd for C85H71BF20N2NiO2:
C, 63.73; H, 4.47; N, 1.75. Found: C, 63.61; H, 4.51; N, 1.72.
Mass spectrum (MALDI): m/z: 921.6 ([Mþ -borate], 100).
[(ArNdC(S(CH2)2S)CdNAr)Ni(acac)]B(C6F5)4 (9a, Ar =
2,6-(3-(CH3)C6H4)2C6H3). Dithiane-bridged diimine 7a (1.1 g,
1.67 mmol), Ni(acac)2 (429 mg, 1.67 mmol), and [CPh3]-
[B(C6F5)4] (1.54 g, 1.67 mmol) were used; red solid; yield: 2.3 g
(92%). 1H NMR (400.13 MHz, C2D2Cl4, 298 K) δ: 7.51 (t, 2H,
Harom), 7.30-7.33 (m, 12H, Harom), 7.20-7.24 (m, 8H, Harom),
5.32 (s, 1H, CH), 2.65 (s, 4H, CH2), 2.37 (s, 12H, CH3), 1.58 (s,
6H, CH3). Anal. Calcd for C73H45BF20N2NiO2S2: C, 58.62; H,
3.03; N, 1.87. Found: C, 58.49; H, 3.05; N, 1.81. Mass spectrum
(MALDI): m/z: 815.3 ([Mþ -borate], 100).
General Procedure for Gas Phase Polymerization of Ethylene.
Sodium chloride (100 g) was heated at 150 °C. The pressure
reactor was evacuated at 110 °C. The dried sodium chloride was
put together with the supported catalyst into the reaction vessel.
Argon was removed and ethylene (ethylene/hydrogen) was
pressured into the reactor and maintained at 5 bar. The reactor
was heated up to the desired temperature. The polymerization
temperature inside kept constant through an outside water
cooling. The polymerization was started by injection TMA
(2 M in toluene) through a pressure buret with 10 bar ethylene
(ethylene/hydrogen) and was carried out for 1 h at constant
pressure. After that time, the reactor was decompressed and the
polymer particles were separated by washing in acidified water.
The polymer was filtered and dried in vacuo at 80 °C overnight.
General Procedure for Solution Polymerization of Ethylene.
The autoclave was evacuated at 125 °C. 9c (5 μmol) and 9d
(10 μmol) were dissolved in dry methylene chloride (4 mL). Dry
toluene (800 mL) was added, followed by the complex solution.
Argon was removed and ethylene (ethylene/hydrogen) was
pressured into the reactor and maintained at 5 bar. The reactor
was heated up to the desired temperature. The polymerization
was started by injection TMA (2 M in toluene) through a pressure
buret with 10 bar of ethylene (ethylene/hydrogen). The polym-
erization temperature inside kept constant through an inside
water cooling as well as the ethylene pressure. The reaction was
carried out for 1 h. After that time, the reactor was decom-
pressed and the reaction mixture was put in acidified methanol
and stirred for 1 h. The polymer was filtered and dried in vacuo
at 80 °C overnight.
[(ArNdC(S(CH2)2S)CdNAr)Ni(acac)]B(C6F5)4 (9b, Ar =
2,6-(3,4-(CH3)2C6H3)2C6H3). Dithiane-bridged diimine 7b (1.2 g,
1.68 mmol), Ni(acac)2 (431 mg, 1.68 mmol), and [CPh3][B(C6F5)4]
1
(1.55 g, 1.68 mmol) were used; red solid; yield: 2.3 g (88%). H
NMR (400.13 MHz, C2D2Cl4, 298 K): δ: 7.51 (t, 2H, Harom), 7.32
(d, 4H, Harom), 7.23-7.25 (m, 8H, Harom), 7.13(d, 4H, Harom), 5.33
(s, 1H, CH), 2.63 (s, 4H, CH2), 2.36 (s, 12H, CH3), 2.28 (s, 12H,
CH3), 1.51 (s, 6H, CH3). Anal. Calcd for C77H53BF20N2NiO2S2:
C, 59.59; H, 3.44; N, 1.81. Found: C, 59.65; H, 3.47; N, 1.76. Mass
spectrum (MALDI): m/z: 871.4 ([Mþ - borate], 100).
Synthesis of the Precatalysts. The silica gel SP9-496 was
heated at 350 °C in vacuo. The dried silica gel was slurried in dry
methylene chloride and the desired amount of the complex was
added. The mixture was shaken for 2 h, the solvent was removed
in vacuo and the resulting residue was washed two times with
dry n-pentane and dried in vacuo. For precatalysts 10a1 and
11a1, the solvent was filtered off and the residue was washed two
times with dry n-pentane and dried in vacuo.
10a (1 wt % Ni). Silica gel (300 mg), complex 8a (97 mg), and
methylene chloride (5 mL) were used. Theoretical nickel load-
ing: 1 wt %. Anal. Calcd for 1 wt % Ni: C, 14.95. Found: C,
15.95 (1.06 wt % Ni). ICP-AES: 0,973 wt % Ni.
10a1 (0.24 wt % Ni). Silica gel (300 mg), complex 8a (97 mg),
and methylene chloride (5 mL) were used. Theoretical nickel
loading: 1 wt %. Anal. Calcd for 1 wt % Ni: C, 14.95. Found: C,
3.61 (0.24 wt % Ni).
10a2 (0.25 wt % Ni). Silica gel (200 mg), complex 8a (12.9 mg),
and methylene chloride (4 mL) were used. Theoretical nickel
loading: 0.25 wt %. Anal. Calcd for 0.25 wt % Ni: C, 3.74.
Found: C, 3.93 (0.26 wt % Ni).
10b (1 wt % Ni). Silica gel (340 mg), complex 8b (115.5 mg),
and methylene chloride (7 mL) were used. Theoretical nickel
loading: 1 wt %. Anal. Calcd for 1 wt % Ni: C, 15.76. Found: C,
16.12 (1.02 wt % Ni).
10c (1 wt % Ni). Silica gel (300 mg), complex 8c (101.9 mg),
and methylene chloride (5 mL) were used. Theoretical nickel
loading: 1 wt %. Anal. Calcd for 1 wt % Ni: C, 15.76. Found: C,
15.91 (1.01 wt % Ni).
10d (1 wt % Ni). Silica gel (350 mg), complex 8d (131.2 mg),
and methylene chloride (7 mL) were used. Theoretical nickel
loading: 1 wt %. Anal. Calcd for 1 wt % Ni: C, 17.41. Found: C,
17.66 (1.01 wt % Ni).
Video Microscopy Experiments. A small metal cylinder with
glass plates on the top was placed in a minireactor (200 mL) with
a glass window. The reactor was heated at 80 °C in vacuo. A
small amount of the precatalyst 10a2 was distributed on the
glass plates. TMA (0.1 mL) was placed on the bottom, and the
argon atmosphere was exchanged against ethylene (4 bar). The
autoclave was heated at 60 °C. Then the camera was started, and
images of the particles were recorded.
Acknowledgment. The financial support of E. I. du Pont de
Nemours & Co. is gratefully acknowledged.
Note Added after ASAP Publication. This article was pub-
lished on the web on March 17, 2010. Due to a production error,
several values in Table 2 were incorrect. The correct version was
published on March 23, 2010.
Supporting Information Available: Crystallographic infor-
mation file (cif file) for complex 8c. This material is available free
of charge via the Internet at http://pubs.acs.org.
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