2,6-Dibenzhydryl-N-(2-phenyliminoacenaphthylenylidene)-4-chloro-aniline nickel dihalides: Synthesis, characterization and ethylene polymerization for polyethylenes with high molecular weights

Article abstract of DOI:10.1016/j.jorganchem.2012.12.009

A series of 2,6-dibenzhydryl-N-(2-phenyliminoacenaphthylenylidene)-4- chloroanilines (L1-L5) and their nickel halide complexes LNiX₂ (X = Br, C1-C5; X = Cl, C6-C10) were synthesized. All organic compounds were characterized by FT-IR and NMR spectroscopy and elemental analysis. The nickel complexes were characterized by FT-IR spectroscopy, elemental analysis and their structures were determined by single-crystal X-ray diffraction. Upon activation with MAO, all of these nickel complexes showed high activities (up to 10 ⁷ g of PE (mol of Ni)^-1 h^-1) for ethylene polymerization. The resulting polyethylenes possess high molecular weights (M_w up to 10⁶ g mol^-1) and feature high degrees of branching. The MM-QEq method was employed to assess the ligands' effects on catalytic activities. The results show that higher net charges on the nickel core correlate directly with higher measured activities.

Full text of DOI:10.1016/j.jorganchem.2012.12.009

Journal of Organometallic Chemistry 725 (2013) 37e45
Contents lists available at SciVerse ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
2,6-Dibenzhydryl-N-(2-phenyliminoacenaphthylenylidene)-4-chloro-
aniline nickel dihalides: Synthesis, characterization and ethylene
polymerization for polyethylenes with high molecular weights
,
,
b
b
b
,
c,
***
Shaoliang Kong a b, Cun-Yue Guo a , Wenhong Yang , Lin Wang , Wen-Hua Sun , Rainer Glaser
**
*
a School of Chemistry and Chemical Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
b Key Laboratory of Engineering Plastics and Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
c Department of Chemistry, University of Missouri, Columbia, MO 65211, United States
a r t i c l e i n f o
a b s t r a c t
Article history:
A
series of 2,6-dibenzhydryl-N-(2-phenyliminoacenaphthylenylidene)-4-chloroanilines (L1eL5) and
Received 24 August 2012
Received in revised form
5 December 2012
their nickel halide complexes LNiX2 (X ¼ Br, C1eC5; X ¼ Cl, C6eC10) were synthesized. All organic
compounds were characterized by FT-IR and NMR spectroscopy and elemental analysis. The nickel
complexes were characterized by FT-IR spectroscopy, elemental analysis and their structures were
determined by single-crystal X-ray diffraction. Upon activation with MAO, all of these nickel complexes
Accepted 6 December 2012
showed high activities (up to 107 g of PE (mol of Ni)ꢀ1 ꢀ1) for ethylene polymerization. The resulting
h
Dedicated to Prof. Dr. Joachim W. Heinicke
on the occasion of his 65th birthday.
polyethylenes possess high molecular weights (Mw up to 106 g molꢀ1) and feature high degrees of
branching. The MM-QEq method was employed to assess the ligands’ effects on catalytic activities. The
results show that higher net charges on the nickel core correlate directly with higher measured activities.
Ó 2012 Elsevier B.V. All rights reserved.
Keywords:
a
-Diimine nickel complex
Polymerization
High molecular weight
High branching
Theoretical calculations
1. Introduction
the parent ligand [47] and the unique properties of the resulting
polyethylenes [48]. Moreover, adaptations of the reaction parame-
In 1995, it was discovered that
and Pd(II) are highly active pre-catalysts for ethylene polymeriza-
tion [1e3]. It is the significant feature of these catalysts that the
sterically bulky ligands prevent the b-elimination chain termination
a
-diimino metal halides of Ni(II)
ters not only change the catalytic activities but also significantly
affect the microstructures of the resulting polymers [49e51].
Furthermore, extensive studies have explored ligands with modi-
fied back-bones [52e54] or different chelating atoms [55e58].
leading to oligomers [4]. Such pre-catalysts with bidentate ligands
of the types N Nˇ [5e14], N ˇ O [15e20], N ˇ P [21e27], P ˇ O [28e31], and
also with tridentˇ ate ligands of the types N Nˇ ˇ N [32e40], N ˇ N ˇ O
[8,41,42], and N Pˇ N [43,44] have since been extensively explored in
ethylene polymerization, and some of them have been employed
in co-polymerization with functional co-monomers [45,46]. The
Among the studies of nickel pre-catalysts bearing
ligands, only a few papers employed unsymmetrical
a
a
-diimine
-diimine
ligands [59]. With the use of unsymmetrical alpha-diimine ligands,
it is thought that one bulky N-imine prevents the -elimination
b
chain termination and that the other N-imine is helpful to produce
highly branched polyethylene. For example, the use of 2,6-
dibenzhydryl-4-methylaniline as one of the anilines in the forma-
cationic a-diimino nickel systems have been attractive because of
the easy variability of the ligands by the substitution pattern of
tion of unsymmetrical a-diimine ligands produced diimino nickel
bromides with one of the highest activities amongst reported dii-
mino nickel halide pre-catalysts and produced highly branched
polyethylene [60]. Pre-catalysts bearing ligands formed with the
isomeric 2,4-dibenzhydryl-N-(2-aryliminoacenaphthylenylidene)-
6-methylaniline also were successful [61].
* Corresponding author. Tel.: þ86 10 62557955; fax: þ86 10 62618239.
** Corresponding author.
*** Corresponding author.
E-mail addresses: cyguo@ucas.ac.cn (C.-Y. Guo), whsun@iccas.ac.cn (W.-H. Sun),
glaserr@missouri.edu (R. Glaser).
In this paper we explore the effects of the replacement of the
4-methyl group of 2,6-dibenzhydryl-4-methylaniline by chlorine to
0022-328X/$ e see front matter Ó 2012 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.jorganchem.2012.12.009

38
S. Kong et al. / Journal of Organometallic Chemistry 725 (2013) 37e45
further probe the relationship between the structures of the ligands
and the catalytic activities of their complex pre-catalysts. Thus,
2.2. X-ray crystallographic studies
the new
a
-diimines L1eL5, derivatives of 2,6-dibenzhydryl-
Single crystals of C1, C3 and C6 suitable for X-ray diffraction
analysis were obtained by slow diffusion of diethyl ether into
dichloromethane solutions. The solid-state structures of C1, C3 and
C6 are shown in Figs. 1e3 and selected bond lengths and bond
angles are provided in Table 1. Their molecular structures indicate
distorted tetrahedral coordination of nickel and this is consistent
with the structures of the 4-methyl analogs reported previously
[60]. As an example, we discuss the crystal structure of C1. In C1, the
atoms N1, N2 and Br2 form the basal plane, the apical position is
N-(2-aryliminoacenaphthylenylidene)-4-chloroaniline, have been
prepared and have been employed to synthesize the nickel halide
complexes C1eC10 (Scheme 1). Upon activation by the MAO
co-catalyst, all nickel complexes were found to exhibit high activity
for ethylene polymerization and to produce polyethylenes with
high molecular weights and narrow polydispersity. Calculations by
the metal atom net charge correlation (MANCC) method [62e65]
are successfully employed to correlate the nature of the organic
ligands and the catalytic activities of their corresponding complex
pre-catalysts.
ꢀ
occupied by atom Br1, and the Ni atom is placed 0.941 A above the
ꢀ
basal plane. The NieBr bond lengths are 2.350(7) A (NieBr1) and
ꢀ
2.342(8) (NieBr2) A and are quite similar. On the other hand, the
ꢀ
ꢀ
NieN bond lengths of 2.048(3) A (NieN1) and 2.010(3) A (NieN2)
differ slightly more and this reflects the different steric demand
of the two aryl groups linked to the coordinating N atoms. The C]N
2. Results and discussion
ꢀ
2.1. Synthesis and characterization of diimines L1eL5 and of their
nickel complexes C1eC10
bonds have bond lengths of d(N1eC12) ¼ 1.283(5) A and d(N2e
ꢀ
C1) ¼ 1.280(5) A, respectively. The best planes of the two arenes
linked to the imine-N atoms are nearly perpendicular with respect
to the plane of the acenaphthylene; with dihedral angles of 87.63ꢁ
for the arene at N2 (contains C45eC50) and of 87.53ꢁ for the arene
at N1 (contains C13eC18).
The syntheses of 2,6-dibenzhydryl-N-(2-aryliminoacenaphthyl-
enylidene)-4-chloroaniline derivatives L1eL5 and of their nickel
halide complexes C1eC10 are outlined in Scheme 1. The reaction of
acenaphthylene-1,2-dione and 2,6-dibenzhydryl-4-chloroaniline
produced 2-(2,6-dibenzhydryl-4-chlorophenylimino)acenaphthy-
lenone, which was further reacted with various anilines to afford the
2.3. Ethylene polymerization
unsymmetrical a-diimines L1eL5. All organic compounds werewell
Complex C4 was screened under 10 atm ethylene with various
alkylaluminium reagents as co-catalysts (Table 2) including meth-
ylaluminoxane (MAO), modified methylaluminoxane (MMAO),
diethylaluminium chloride (AlEt2Cl), and ethylaluminium sesqui-
chloride (EASC). The best performance was observed with co-
catalyst MAO (Entry 1 in Table 2). The polyethylene with highest
molecular weight was obtained with MMAO (Entry 2 in Table 2).
Seeking primarily high activities, MAO was used as activator in
further optimizations of the reaction parameters.
characterized by FT-IR and NMR spectroscopy and their elemental
analyses were consistent with their formulas. Compounds L1eL5
reacted with (DME)NiBr2 or (DME)NiCl2, respectively, in dichloro-
methane to form their corresponding bromide C1eC5 or chloride
C6eC10 complexes, respectively. The complexes were identified by
IR spectroscopy and elemental analysis. In their IR spectra, a band in
the range 1580e1590 cmꢀ1 can be ascribed to the stretching
vibration of C]N. As compared to the corresponding free ligand,
the IR spectra of all compounds show a red shift of n(C]N) by ca.
On variation of the Al/Ni ratios from 2000 to 3500 at 20 ꢁC
(entries 1e4 in Table 3), the optimum activity of 1.10 ꢂ 107 g PE (mol
Ni)ꢀ1 hꢀ1 was observed with the Al/Ni ratio of 3000 and producing
polyethylene with a relatively higher molecular weight. This
phenomenon is consistent with observations of its analogs [60,61].
When reaction temperatures were varied within the range from
20 ꢁC to 60 ꢁC (entries 3, 5e7 in Table 3) with the Al/Ni ratio of 3000
50e60 cmꢀ1, which reflects the coordination of the imine nitrogen
atoms to the nickel atom. Furthermore, the structures of C1, C3 and
C6 were determined by single-crystal X-ray diffraction analysis.
CHPh2
Cl
NH2
CHPh2
CHPh2
N
O
p-TsOH
toluene
Cl
CHPh2
O
O
R1
R1
R1
Me Et iPr Me Et
p-TsOH
R2
L
R2
NH2
H
L1 L2 L3 L4 L5
H
H
Me Me
toluene
X = Br
C1 C2 C3 C4 C5
X = Cl C6 C7 C8 C9 C10
(DME)NiX2
R1
CH2Cl2
CHPh2
R1
CHPh2
N
N
N
N
X
Ni
X
Cl
CHPh2 R1
R2
Cl
CHPh2 R1
X = Br: C1-C5; X = Cl: C6-C10
R2
L1-L5
Fig. 1. ORTEP drawing of C1. Thermal ellipsoids are shown at the 30% probability level.
Scheme 1. Synthesis of ligands L1eL5 and of their nickel complexes C1eC10.
Hydrogen atoms have been omitted for clarity.

S. Kong et al. / Journal of Organometallic Chemistry 725 (2013) 37e45
39
Table 1
ꢁ
ꢀ
Selected bond lengths (A) and angles ( ) for complexes C1, C3 and C6.
C1
C3
C6
X
Br
Br
Cl
ꢀ
Bond lengths (A)
NieX(1)
2.350(7)
2.351(8)
2.209(13)
NieX(2)
NieN(1)
NieN(2)
N(1)eC(12)
N(1)eC(13)
N(2)eC(1)
N(2)eC(45)
Cl(1)eC(16)
Bond angles (ꢁ)
N(2)eNieN(1)
X(2)eNieX(1)
N(1)eNieX(2)
N(1)eNieX(1)
N(2)eNieX(1)
N(2)eNieX(2)
2.342(8)
2.048(3)
2.010(3)
1.283(5)
1.446(5)
1.280(5)
1.451(5)
1.738(4)
2.325(10)
2.037(3)
2.015(3)
1.293(4)
1.437(4)
1.287(4)
1.450(4)
1.740(3)
2.216(13)
2.049(3)
2.015(9)
1.291(5)
1.451(5)
1.282(5)
1.442(5)
1.745(4)
83.16(12)
122.41(3)
113.66(8)
111.65(9)
111.60(9)
107.34(9)
82.89(12)
124.72(3)
115.11(8)
106.61(8)
109.91(8)
109.75(9)
83.27(14)
124.92(5)
112.26(11)
110.18(10)
112.06(10)
106.31(11)
Fig. 2. ORTEP drawing of C3. Thermal ellipsoids are shown at the 30% probability level.
Hydrogen atoms have been omitted for clarity.
the formation of branched polyethylenes by active nickel species
through -hydrogen migration [48,51,60,61].
b
under 10 atm ethylene, the catalytic activities decreased signifi-
cantly and the resulting polyethylenes showed lower molecular
weights. This observation also agrees with previous observations
To understand the influence of the nature of ligands on the
catalytic behavior of their nickel complexes, all bromide complexes
were employed for ethylene polymerization under the same reac-
tion conditions with an Al/Ni molar ratio of 3000, at 20 ꢁC and under
10 atm ethylene pressure (entries 3, 13e16 in Table 3). The current
classes of pre-catalysts showed relatively higher activities in
comparison to the catalytic behavior of their 4-methyl
analogs [60]. The activities were highest for C4 (with 2,4,6-
trimethylphenylamino-) and the activity decreased in the order
C4 > C1 (with 2,6-dimethylphenylamino-) > C5 (with 2,6-diethyl-4-
methylphenylamino-) > C2 (with 2,6-diethylphenyl-amino-) > C3
(with 2,6-diisopropylphenylamino-). This ordering is consistent
with the observations that low steric demand of the ortho-substit-
uent and of the methyl substituent in the para-position enhance the
catalytic activities of their pre-catalysts [60,68e70]. Pre-catalysts
with bulky R1 substituents result in polyethylenes with higher
molecular weights but with near constant polydispersity. This
observation indicates that the bulky ligands hinder the chain
termination during the polymerization and produce polyethylenes
with higher molecular weights.
of
a-diimino nickel analogs [49,60,61], and is ascribed to lower
solubility of ethylene and higher chain termination at the elevated
temperature. With lower pressure of ethylene (entries 3, 8, 9 in
Table 3), reduced activities were observed due to lower concen-
tration of ethylene monomer. With regard to the lifetime of active
species (entries 3, 10e12 in Table 3), slight deactivations were
observed which probably were caused by impurities in the
ethylene source and the limitation of mass transfer due to the
formation of insoluble polyethylene.
To assess any branching of the obtained PE samples, their IR
spectra were recorded on a PerkineElmer System 2000 FT-IR
spectrometer for samples with 0.2e0.6 mm thick membranes.
The analysis of the spectra [66] indicated branched polyethylenes
with over 40 branches for every 1000 carbons. For the polyethylene
with a low molecular weight (Entry 7 in Table 3), the 13C
NMR measurement [67] (Fig. 4) shows branching of 98 branches/
1000C and this result agrees closely with the IR analysis.
Our measurements corroborate and agree with other reports of
As for the chloride complexes, the optimization of the catalytic
parameters was tried with complex C9, the chloride analog of the
bromide complex C4 (entries 1e6 in Table 4). The results indicate
that the chloride pre-catalyst required a smaller amount of
co-catalyst MAO. The assessment of the influence of the nature of
ligands on the catalytic behavior was repeated with all of the
chloride complex pre-catalysts.
Comparison of the two data sets obtained for bromide and
chloride complexes showed no significant effect of the nature of the
halide on the catalytic activities under the optimal conditions.
Table 2
Ethylene polymerization by pre-catalyst C4 with various co-catalystsa.
Entry Co-cat. Al/Ni T/ꢁC Activityb Tm /ꢁC Mwd/105 g molꢀ1 Mw/Mn
c
d
1
2
3
4
MAO
MMAO 3000 20
Et2AlCl
EASC
3000 20
11.0
2.71
4.07
3.10
94.6
93.0
89.8
90.4
6.33
18.6
3.23
2.37
2.9
2.7
2.2
2.2
600 20
600 20
a
b
c
Conditions: 1.5 mmol of C4 30 min; 10 atm of ethylene; total volume 100 mL.
106 g of PE (mol of Ni)ꢀ1 hꢀ1
Determined by DSC.
.
Fig. 3. ORTEP drawing of C6. Thermal ellipsoids are shown at the 30% probability level.
Hydrogen atoms have been omitted for clarity.
d
Determined by GPC.

40
S. Kong et al. / Journal of Organometallic Chemistry 725 (2013) 37e45
Table 3
Results of ethylene polymerization catalyzed by C1eC5 with MAOa.
Entry
Pre-cat.
Al/Ni
T/ꢁC
t/min
P(C2H4)/atm
Activityb
Mwd/105 g molꢀ1
Mw/Mn
Branches/1000Ce
c
Tm /ꢁC
d
1
2
3
4
5
6
7
8
C4
C4
C4
C4
C4
C4
C4
C4
C4
C4
C4
C4
C1
C2
C3
C5
2000
2500
3000
3500
3000
3000
3000
3000
3000
3000
3000
3000
3000
3000
3000
3000
20
20
20
20
30
40
60
20
20
20
20
20
20
20
20
20
30
30
30
30
30
30
30
30
30
10
20
60
30
30
30
30
10
10
10
10
10
10
10
5
3.98
6.31
11.0
8.17
8.33
6.96
3.79
6.70
0.74
14.8
12.3
6.81
9.80
8.21
7.20
9.10
99.0
98.0
94.6
92.8
93.6
69.8
47.8
87.2
31.4
98.8
96.7
102.5
94.8
94.1
88.6
91.2
3.15
4.79
6.40
6.33
4.68
3.46
2.97
4.34
4.32
5.98
5.96
9.80
4.38
5.44
12.9
6.43
2.5
2.4
2.8
2.9
2.3
2.5
3.2
2.4
5.4
2.3
2.9
2.8
2.4
2.5
2.5
2.6
35
43
50
28
53
80
90
80
160
37
44
46
53
50
40
66
9
1
10
11
12
13
14
15
16
10
10
10
10
10
10
10
a
Conditions: 1.5 mmol of Ni; total volume 100 mL.
b
c
106 g of PE (mol of Ni)ꢀ1 hꢀ1
Determined by DSC.
.
d
e
Determined by GPC.
Determined by FT-IR.
The active species derived from both halide pre-catalysts should be
verysimilarand halogen abstraction is facile in both cases [71]. There
was a halide effect and different Al/Ni ratio effect on the properties of
their resulting polyethylenes in that the polyethylenes produced
with the chloride pre-catalysts (entries 5, 7e10 in Table 4) showed
relatively higher molecular weights than those produced with the
bromide pre-catalysts (entries 3, 13e16 in Table 3). In this work, the
halide effect can be seenclearly. Forexample, on fixingthe Al/Niratio
to 2500 (entry 2 in Table 3, entry 4 in Table 4), the bromide and
chloride complexes show similar activity (6.31e7.65 ꢂ 106 g of PE
here to the complex pre-catalysts and assuming that the ligand
binding in the electronic ground state of the complex pre-catalysts
parallels the ligand binding in the active species. In previous
studies, the experimentally determined catalytic activities were
shown to correlate with metal charges computed by the MANCC
method for catalytic systems of Ti [62], Ni [63,64] and Fe [65].
Molecular models were built using Material Studio software and
then optimized with molecular mechanics (MM). We chose the
Dreiding force field [72] for its advantage of relatively simple
parameters and the ease of its extension to other metals. For the
present study, atom types were added into the force field files for
nickel atom and the atoms bonded to nickel and their parameters
were derived from our X-ray crystal data as described previously
[64]. The nonbonded potential truncation was performed using the
spherical cutoff method for van der Waals potentials and electro-
static interactions, with the cutoff distance of 1.85 nm. To obtain net
charge on each atom of the pre-catalysts, the MANCC method
combines the MM and QEq theoretical methods as follows. In the
first step, charges were distributed on each atom by QEq on a given
pre-catalyst molecule and MM structure optimizations were per-
formed until the energy had converged. In the second step, net
charges on each atom were refined by the QEq method and using
the optimized structure obtained in the first step.
(mol of Ni)ꢀ1
h
ꢀ1), while the resultant polyolefin obtained from
chloride compounds displayed higher molecular weight and
wider PDI.
2.4. Theoretical calculation of catalyst activity
MANCC calculations were performed to investigate the corre-
lation between the nature of the ligands (i.e., their substituents)
and the catalytic activities of the complex pre-catalysts [62e65].
The MANCC method combines a molecular mechanics (MM)
approach with QEq charge distributions. The method is applied
The net charges of all of the nickel complexes were calculated by
the MANCC method and the results are tabulated in Table 5 and
plots are shown in Fig. 5. Within the two groups of the bromide or
chloride nickel complexes, respectively, the experimentally
measured catalytic activities increased with the net charges of
the nickel centers in the pre-catalysts. This trend is in line with
previous calculation results for other nickel complex pre-catalysts
[63,64], and also in line with expectation based on the plausible
mechanism of polymerization.
In the olefin polymerization mechanism, the olefin coordination
to the central metal or its insertion into the MeR bond (R alky
chain) is the most likely turnover limiting step, and both are
considered to be directly and closely related to the electrophilicity
of the central metal [3,5,49,73]. Thus, a higher net charge of the
metal core would enhance its coordination ability and thereby
increase the catalyst’s activity. Ligand effects on catalytic activities
should be especially pronounced for electron-rich transition metal
complexes and these include complexes of Ni2þ ion (3d8). In
particular, this interpretation also is consistent with and accounts
13
Fig. 4. C NMR spectrum of the polyethylene formed by C4/MAO at 60 ꢁC (Entry 7 in
Table 3).

S. Kong et al. / Journal of Organometallic Chemistry 725 (2013) 37e45
41
Table 4
Results of ethylene polymerization catalyzed by C6eC10 with MAOa.
Entry
Pre-cat.
Al/Ni
T/ꢁC
Activityb
Mwd/105 g molꢀ1
Mw/Mn
Branches/1000Ce
c
Tm /ꢁC
d
1
2
3
4
5
6
7
8
9
10
C9
C9
C9
C9
C9
C9
C6
C7
C8
C10
1000
1500
2000
2500
3000
1500
1500
1500
1500
1500
20
20
20
20
20
30
20
20
20
20
5.42
9.86
7.91
7.65
6.48
4.02
9.81
7.89
5.68
8.10
104.3
92.2
89.5
97.9
103.3
77.8
95.7
95.6
102.3
96.6
4.17
5.63
6.78
6.89
7.89
4.31
5.49
12.5
24.1
22.9
2.6
3.0
3.8
3.2
4.6
3.4
3.3
3.2
2.9
3.3
30
64
57
48
36
70
53
50
25
44
a
Conditions: 1.5 mmol of Ni; 30 min; 10 atm of ethylene; total volume 100 mL.
b
c
106 g of PE (mol of Ni)ꢀ1 hꢀ1
Determined by DSC.
.
d
e
Determined by GPC.
Determined by FT-IR.
for the finding that the current pre-catalysts with 4-chloro
groups show higher activities than their analogs with 4-methyl
groups [60].
PL-GPC220 at 150 ꢁC, with 1,2,4-trichlorobenzene as the solvent.
The melting points of polyethylene were measured from the second
scanning run on a PerkineElmer TA-Q2000 differential scanning
calorimetry (DSC) analyzer under a nitrogen atmosphere. In the
procedure, a sample of about 2.0e4.0 mg was heated to 150 ꢁC
a rate of 20 ꢁC/min and kept for 5 min at 150 ꢁC to remove the
thermal history and then cooled at a rate of 20 ꢁC/min to ꢀ20 ꢁC. 13C
NMR spectra of the polyethylenes were recorded on a Bruker DMX
300 MHz instrument at 135 ꢁC in deuterated 1,2-dichlorobenzene
with TMS as an internal standard.
3. Conclusions
A series of bulky unsymmetrical
a-diimines was synthesized
and reacted with (DME)NiX2 (X ¼ Br, Cl) to form bromide or
chloride nickel complexes, respectively. Activated by the co-catalyst
MAO, all of these nickel complex pre-catalysts showed high cata-
lytic activity for the polymerization of ethylene (up to 1.48 ꢂ 107 g
of PE (mol of Ni)ꢀ1
h
ꢀ1) leading to polyethylenes with high
4.2. Syntheses and characterization
molecular weights and with narrow polydispersity. The results
suggest that ligands that increase of the net charge on the nickel
center enhance the catalytic activities of the pre-catalysts in
ethylene polymerization.
4.2.1. 2-(2,6-Dibenzhydryl-4-chlorophenylimino)acenaphthylenone
A
solution of 2,6-diphenylmethyl-4-chloroaniline (1.29 g,
2.8 mmol), acenaphthylene-1,2-dione (0.51 g, 3.3 mmol), and
a catalytic amount of p-toluenesulfonic acid in toluene (120 mL)
were stirred and refluxed for 3 h. After solvent evaporation at
reduced pressure, the crude product was dissolved in a minimum
amount of CH2Cl2. The CH2Cl2 solution was mixed with petroleum
ether, and a yellow powder was obtained upon standing at room
temperature. Yield: 1.33 g (78%). Mp: 236e237 ꢁC. 1H NMR
4. Experimental section
4.1. General procedures
All work involving air- and/or moisture-sensitive compounds
was performed using standard Schlenk techniques under a nitrogen
atmosphere. Toluene was refluxed over sodium benzophenone and
distilled under nitrogen prior to use. Methylaluminoxane (MAO,
1.46 mol/L solution in toluene) and modified methylaluminoxane
(MMAO, 1.93 mol/L in heptane, 3A) were purchased from Akzo
Nobel Corp. Diethylaluminium chloride (Et2AlCl, 0.79 mol/L in
toluene) and ethylaluminium sesquichloride (EASC, 0.87 mol/L in
toluene) were purchased from Acros Chemicals. High-purity
ethylene was purchased from Beijing Yanshan Petrochemical Co.
and used as received. Other reagents were purchased from Aldrich,
Acros, or local suppliers. NMR spectra were recorded on a Bruker
DMX 400 MHz instrument at ambient temperature using TMS as an
(400 MHz, CDCl3, TMS):
d
8.03 (d, J ¼ 5.82 Hz, 2H), 7.71 (m, 2H),
7.26e7.23 (m, 4H), 7.19 (t, J ¼ 6.72 Hz, 2H), 7.06 (m, 5H), 6.97 (s, 2H),
6.84 (d, J ¼ 7.36 Hz, 5H), 6.60 (t, J ¼ 7.28 Hz, 3H), 6.43 (t, J ¼ 7.21 Hz,
2H), 6.17 (d, J ¼ 6.97 Hz, 1H), 5.43 (s, 2H). 13C NMR (100 MHz, CDCl3,
TMS):
d 189.47, 162.67, 146.95, 142.74, 142.11, 141.01, 134.22, 132.11,
130.05, 129.97, 129.72, 129.48, 129.00, 128.53, 128.24, 128.16, 127.86,
127.38, 126.81, 126.74, 126.00, 123.98, 121.88, 52.29. IR (KBr; cmꢀ1):
3026 (w), 1722 (s), 1659 (m), 1594 (s), 1491 (s), 1431 (s), 1273 (m),
1072 (m), 1029 (s), 889 (m), 826 (m), 777 (s), 737 (s), 694 (vs). Anal.
Calcd for C44H30ClNO (624.17): C, 84.67; H, 4.84; N, 2.24. Found: C,
84.31; H, 4.88; N, 2.21.
internal standard;
d
values are given in ppm and J values in Hz. IR
4.2.2. Synthesis of 2,6-dibenzhydryl-N-(2-phenyliminoacenaphthyl-
enylidene)-4-chlorobenzenamine (L1eL5)
4.2.2.1. 2,6-Dibenzhydryl-N-(2-(2,6-dimethylphenylimino)acenaph-
thylenylidene)-4-chlorobenzenamine (L1). To a solution of 2-(2,6-
dibenzhydryl-4-chlorophenylimino)acenaphthylenone (0.30 mg,
spectra were recorded on a PerkineElmer System 2000 FT-IR
spectrometer. Elemental analysis was carried out using a Flash
EA 1112 micro-analyzer. Molecular weights and molecular
weight distribution (MWD) of polyethylene were determined by
Table 5
Calculated charge of nickel atom in complexes C1eC10.
C1
C2
C3
C4
0.394
11.0
C5
C6
C7
C8
C9
C10
Charge on Ni
Obs. activitya
0.393
9.80
0.389
8.21
0.387
7.20
0.390
9.10
0.443
9.81
0.440
7.89
0.429
5.68
0.445
9.86
0.442
8.10
a
Values in units of 106 g of PE (mol of Ni)ꢀ1 hꢀ1
.

42
S. Kong et al. / Journal of Organometallic Chemistry 725 (2013) 37e45
4H), 6.98 (m, 3H), 6.91 (d, J ¼ 7.36 Hz, 4H), 6.60 (t, J ¼ 7.52 Hz, 4H),
6.52 (d, J ¼ 6.93 Hz, 1H), 6.42 (t, J ¼ 6.66 Hz, 2H), 6.05 (d, J ¼ 7.20 Hz,
1H), 5.62 (s, 2H), 2.68 (m, 2H), 2.51 (m, 2H), 1.16 (m, 6H). 13C NMR
(100 MHz, CDCl3, TMS):
d 163.91, 161.60, 148.26, 147.83, 142.57,
140.99, 140.08, 134.65, 130.67, 129.87, 129.78, 129.54, 129.00,
128.71, 128.39, 128.30, 128.03, 127.46, 126.98, 126.56, 126.27,
125.89, 124.29, 122.51, 52.27, 24.54, 14.28. IR (KBr; cmꢀ1): 3027 (w),
2966 (w), 1661 (m), 1588 (m), 1491 (s), 1426 (s), 1266 (w), 1181 (m),
1079 (m), 1032 (s), 919 (w), 887 (w), 736 (s), 694 (vs). Anal. Calcd
for C54H43ClN2 (755.39): C, 85.86; H, 5.74; N, 3.71. Found: C, 85.44;
H, 5.98; N, 3.75.
4.2.2.3. 2,6-Dibenzhydryl-N-(2-(2,6-diisopropylphenylimino)ace-
naphthylenylidene)-4-chlorobenzenamine (L3). Using the same
procedure as for the synthesis of L1, except that 2,6-
diisopropylaniline (0.13 g, 0.72 mmol) was in place of
2,6-dimethylaniline, L3 was obtained as a yellow powder in 56%
(0.21 g). Mp: 226e227 ꢁC. 1H NMR (400 MHz, CDCl3, TMS):
d 7.69
(d, J ¼ 8.24 Hz, 1H), 7.54 (d, J ¼ 8.30 Hz, 1H), 7.36e7.26 (m, 7H), 7.21
(d, J ¼ 7.05 Hz, 3H), 7.09 (d, J ¼ 7.20 Hz, 4H), 6.99 (s, 2H), 6.91
(d, J ¼ 7.23 Hz, 5H), 6.58 (t, J ¼ 7.36 Hz, 4H), 6.45e6.38 (m, 3H), 5.95
(d, J ¼ 6.98 Hz, 1H), 5.63 (s, 2H), 3.15 (m, J ¼ 6.64 Hz, 2H), 1.28 (d,
J ¼ 6.66 Hz, 6H), 1.01 (d, J ¼ 6.70 Hz, 6H). 13C NMR (100 MHz, CDCl3,
TMS): d 164.11, 162.09, 147.92, 147.08, 142.75, 140.94, 140.17, 135.79,
134,78,129.82, 129.62,129.06,128.88,128.61,128.43,128.37,128.13,
127.16, 127.05, 126.60, 125.97, 124.78, 124.41, 123.76, 123.18, 53.57,
52.26, 28.67, 24.39, 23.87. IR (KBr; cmꢀ1):3059 (w), 3025 (w), 2960
(s), 1736 (w), 1661 (s), 1594 (s), 1492 (s), 1428 (s), 1267 (s), 1184 (s),
1077 (m), 1037 (s), 923 (m), 886.3 (m), 739 (s), 699 (vs). Anal. Calcd
for C56H47ClN2 (783.44): C, 85.85; H, 6.05; N, 3.58. Found: C, 85.55;
H, 6.34; N, 3.55.
4.2.2.4. 2,6-Dibenzhydryl-N-(2-(2,4,6-trimethylphenylimino)ace-
naphthylenylidene)-4-chlorobenzenamine
(L4). The
synthetic
procedure for L4 was analogous to that for L1, except that
2,4,6-trimethylaniline (0.12 g, 0.72 mmol) was used in place of
2,6-dimethylaniline. Yellow solid of L4 were collected in a yield of
58% (0.21 g). Mp: 238e239 ꢁC. 1H NMR (400 MHz, CDCl3, TMS):
Fig. 5. Variation between calculated net charge on Ni and polymerization activity: (a)
for complexes C1eC5 and (b) for C6eC10.
0.48 mmol), 2,6-dimethylaniline (0.089 g, 0.72 mmol), and a cata-
lytic amount of p-toluenesulfonic acid in 70 mL of toluene at 120 ꢁC
were stirred for 9 h, then the solvent was removed by vacuum
evaporation. The residue was further purified by silica column
chromatography (40/1 petroleum ether/ethyl acetate) to afford
0.19 g of L1 (yellow, 60% yield). Mp: 218e219 ꢁC. 1H NMR (400 MHz,
d
7.72 (d, J ¼ 8.25 Hz, 1H), 7.60 (d, J ¼ 8.25 Hz, 1H), 7.29e7.23
(m, 5H), 7.19 (t, J ¼ 6.92 Hz, 2H), 7.10 (d, J ¼ 7.45 Hz, 4H), 7.02
(t, J ¼ 7.46 Hz, 1H), 6.98 (s, 4H), 6.92 (d, J ¼ 7.58 Hz, 4H), 6.60
(t,
J
¼
7.18 Hz, 5H), 6.42 (t,
J
¼
7.28 Hz, 2H), 6.14 (d,
J ¼ 7.11 Hz, 1H), 5.60 (s, 2H), 2.38 (s, 3H), 2.17 (s, 6H). 13C NMR
(100 MHz, CDCl3, TMS):
d
163.95, 161.55, 147.85,
CDCl3, TMS):
d
7.74 (d, J ¼ 8.24 Hz, 1H), 7.62 (d, J ¼ 8.26 Hz, 1H),
146.46, 142.41, 141.15, 140.12, 134.73, 133.20, 129.99, 129.91, 129.61,
129.22, 129.02, 128.87, 128.49, 128.27, 128.06, 127.77, 127.00, 126.63,
125.91, 124.64, 122.06, 52.38, 21.11, 18.24. IR (KBr; cmꢀ1): 3025 (w),
2963 (w), 1665 (s), 1644 (s), 1597 (m), 1491 (s), 1448 (s), 1427 (s),
1270 (m), 1183 (m), 1076 (m), 1032 (s), 920 (s), 889 (s), 737 (s), 700
(vs). Anal. Calcd for C53H41ClN2 (741.36): C, 85.86; H, 5.57; N, 3.78.
Found: C, 85.51; H, 5.56; N, 3.79.
7.28e7.25 (m, 5H), 7.19 (m, 4H), 7.10 (d, J ¼ 7.26 Hz, 5H), 7.04 (m,
1H), 6.08 (s, 2H) 6.92 (d, J ¼ 7.52 Hz, 4H), 6.61 (t, J ¼ 7.60 Hz, 4H),
6.54 (d, J ¼ 7.10 Hz, 1H), 6.43 (t, J ¼ 7.34 Hz, 2H), 6.14 (d, J ¼ 7.12 Hz,
1H), 5.61 (s, 2H), 2.21 (s, 6H). 13C NMR (100 MHz, CDCl3, TMS):
d
163.98, 161.39, 149.27, 147.79, 142.40, 141.14, 140.14, 134.71,
129.98,129.90, 129.61,129.08, 128.97, 128.74, 128.51, 128.39, 128.30,
128.07, 127.79, 127.04, 126.65, 125.93, 124.88, 124.30, 124.00,
122.03, 52.39, 18.32, 17.78. IR (KBr; cmꢀ1): 3025 (w), 2913 (w), 1976
(w), 1733 (m), 1666 (s), 1593 (s), 1492 (s), 1427 (s), 1239 (s), 1078
(m), 1036 (s), 922 (m), 890 (m), 766 (s), 700 (vs). Anal. Calcd. for
C52H39ClN2 (727.33): C, 85.87; H, 5.40; N, 3.85. Found: C, 85.60; H,
5.49; N, 3.85.
4.2.2.5. 2,6-Dibenzhydryl-N-(2-(2,6-diethyl-4-methylphenylimino)
acenaphthylenylidne)-4-chlorobenzenamine (L5). Using the same
procedure as for the synthesis of L1, except that 2,6-diethyl-
4-methylaniline (0.12 g, 0.72 mmol) was in place of
2,6-dimethylaniline, L5 was obtained as yellow powder in 69%
(0.26 g). Mp: 227e228 ꢁC. 1H NMR (400 MHz, CDCl3, TMS):
d 7.71
4.2.2.2. 2,6-Dibenzhydryl-N-(2-(2,6-diethylphenylimino)acenaph-
thylenylidene)-4-chlorobenzenamine (L2). The synthetic procedure
of L2 was similar to that for L1, except that 2,6-diethylaniline
(0.11 g, 0.72 mmol) was used in place of 2,6-dimethylaniline.
Yellow solid of L2 were collected in a yield of 61% (0.22 g). Mp:
(d, J ¼ 8.27 Hz, 1H), 7.57 (d, J ¼ 8.30 Hz, 1H), 7.28e7.25 (m, 5H),
7.21e7.28 (m, 2H), 7.09 (d, J ¼ 7.44 Hz, 4H), 7.03 (s, 2H), 6.98 (m,
3H), 6.91 (d, J ¼ 7.56 Hz, 4H), 6.59 (t, J ¼ 7.28 Hz, 5H), 6.41 (t,
J ¼ 7.39 Hz, 2H), 6.07 (d, J ¼ 7.10 Hz, 1H), 5.62 (s, 2H), 2.62 (m, 2H),
2.47 (m, 2H), 2.43 (s, 3H), 1.14 (t, J ¼ 7.56 Hz, 6H). 13C NMR
228e229 ꢁC. 1H NMR (400 MHz, CDCl3, TMS):
d
7.71 (d, J ¼ 8.06 Hz,
(100 MHz, CDCl3, TMS): d 164.02, 161.81, 147.92, 145.77, 142.63,
1H), 7.57 (d, J ¼ 8.39 Hz,1H), 7.25e7.20 (m, 10H), 7.09 (d, J ¼ 7.20 Hz,
141.04,140.10,134.72,133.50,130.54,129.84,129.60,128.98,128.85,

S. Kong et al. / Journal of Organometallic Chemistry 725 (2013) 37e45
43
128.71, 128.44, 128.32, 128.07, 127.48, 127.10, 126.60, 125.91, 122.53,
52.30, 24.58, 21.39, 14.69. IR (KBr; cmꢀ1): 3026 (w), 2963 (m), 1672
(m), 1650 (s), 1596 (m), 1492 (m), 1423 (s), 1264 (s), 1184 (m), 1079
(s), 1033 (s), 918 (m), 889 (s), 735 (s), 699 (vs). Anal. Calcd for
C55H45ClN2 (769.41): C, 85.86; H, 5.90; N, 3.64. Found: C, 85.75; H,
6.18; N, 3.34.
synthesis of C6 was carried out in a manner identical with that for
C1. A mixture of the ligand L1 (0.15 g, 0.20 mmol) and (DME)NiCl2
(0.044 g, 0.20 mmol) in dried dichloromethane (10 mL) was stirred
for 24 h at room temperature in a Schlenk tube, then absolute
diethyl ether (10 mL) was added to precipitate the complex. The
deposit was washed with diethyl ether and dried under vacuum to
obtain a red powder of C6 in 80% (0.14 g). IR (KBr; cmꢀ1): 3026 (m),
2925 (w), 1646 (m), 1581 (s), 1493 (m), 1448 (m), 1428 (s), 1292 (m),
1180 (m), 1082 (m), 1033 (m), 921 (m), 893 (s), 774 (vs), 703 (vs).
Anal. Calcd for C52H39Cl3N2Ni (856.93): C, 72.88; H, 4.59; N, 3.27.
Found: C, 72.61; H, 4.56; N, 3.22.
4.2.3. Preparation of the bidentate nickel complexes C1eC10
4.2.3.1. 2,6-Dibenzhydryl-N-(2-(2,6-dimethyl-phenylimino)acenaph-
thylenylidene)-4-chlorobenzenaminonickel dibromide (C1). The
procedure for C1 is described as follows. A mixture of the ligand L1
(0.15 g, 0.20 mmol) and (DME)NiBr2 (0.062 g, 0.20 mmol) in dried
dichloromethane (10 mL) was stirred for 24 h at room temperature
in a Schlenk tube, then absolute diethyl ether (10 mL) was added to
precipitate the complex. The deposit was washed with diethyl
ether and dried under vacuum to obtain a red powder of C1 in 76%
(0.14 g) yield. IR (KBr; cmꢀ1): 3025 (w), 2922 (w),1646 (m),1579 (s),
1492 (m),1450 (m),1427 (s),1264 (m),1180 (m),1082 (m),1032 (m),
921 (m), 892 (s), 773 (vs), 702 (vs). Anal. Calcd for C52H39ClBr2N2Ni
(945.83): C, 66.03; H, 4.16; N, 2.96. Found: C, 65.91; H, 4.14; N, 2.98.
4.2.3.7. 2,6-Dibenzhydryl-N-(2-(2,6-diethylphenylimino)acenaph-
thylenylidene)-4-chlorobenzenaminonickel dichloride (C7). The
synthetic procedure of C7 was similar to that for C6, except that L2
(0.15 g, 0.20 mmol) was used in place of L1 (0.15 g, 0.20 mmol). Red
powder of C7 was collected in a yield of 78% (0.13 g). IR (KBr; cmꢀ1):
3025 (w), 2969 (w), 1625 (s), 1588 (s), 1492 (s), 1426 (s), 1264 (w),
1183 (s), 1079 (m), 1032 (s), 922 (w), 893 (s), 769 (s), 701 (vs). Anal.
Calcd for C54H43Cl3N2Ni (884.99): C, 73.29; H, 4.90; N, 3.17. Found:
C, 73.10; H, 4.65; N, 3.22.
4.2.3.2. 2,6-Dibenzhydryl-N-(2-(2,6-diethylphenylimino)acenaph-
thylenylidene)-4-chlorobenzenaminonickel
dibromide
(C2).
4.2.3.8. 2,6-Dibenzhydryl-N-(2-(2,6-diisopropylphenylimino)ace-
naphthylenylidene)-4-chlorobenzenaminonickel dichloride (C8).
Using the same procedure as for the synthesis of C8, except that L3
(0.16 g, 0.20 mmol) was in place of L1 (0.15 g, 0.20 mmol), C8 was
obtained as red powder in 79% (0.14 g). IR (KBr; cmꢀ1): 3060 (w),
3027 (w), 2967 (m), 1653 (s), 1625 (s), 1591 (s), 1492 (s), 1430 (s),
1291 (m), 1181 (s), 1077 (m), 1032 (m), 921 (m), 892 (s), 768 (vs),
701 (vs). Anal. Calcd for C56H47Cl3N2Ni (913.04): C, 73.67; H, 5.19; N,
3.07. Found: C, 73.55; H, 5.01; N, 2.95.
Using the same procedure as for the synthesis of C1, except that L2
(0.15 g, 0.20 mmol) was used in place of L1 (0.15 g, 0.20 mmol), C2
was obtained as red powder in 86% (0.17 g). IR (KBr; cmꢀ1): 3027
(w), 2967 (w), 1646 (s), 1595 (s), 1492 (s), 1429 (s), 1266 (w), 1181
(s), 1079 (s), 1033 (s), 920 (s), 892 (s), 769 (vs), 701 (vs). Anal. Calcd
for C54H43ClBr2N2Ni (973.89): C, 66.60; H, 4.45; N, 2.88. Found: C,
66.50; H, 4.51; N, 2.64.
4.2.3.3. 2,6-Dibenzhydryl-N-(2-(2,6-diisopropylphenylimino)ace-
naphthylenylidene)-4-chlorobenzenaminonickel dibromide (C3).
The synthetic procedure for C3 was analogous to that for C1,
except that L3 (0.16 g, 0.20 mmol) was used in place of L1 (0.15 g,
0.20 mmol). Red solid of C3 were collected in a yield of 88%
(0.18 g). IR (KBr; cmꢀ1): 3058 (w), 3025 (w), 2967 (m), 1645 (s),
1620 (s), 1581 (s), 1492 (s), 1427 (s), 1290 (m), 1181 (s), 1079 (m),
1037 (s), 922 (m), 892 (s), 768 (vs), 701 (vs). Anal. Calcd for
C56H47ClBr2N2Ni (1001.94): C, 67.13; H, 4.73; N, 2.80. Found: C,
66.83; H, 4.63; N, 2.68.
4.2.3.9. 2,6-Dibenzhydryl-N-(2-(2,4,6-trimethylphenylimino)ace-
naphthylenylidene)-4-chlorobenzenaminonickel dichloride (C9).
The synthetic procedure of C9 was similar to that for C6, except that
L4 (0.15 g, 0.20 mmol) was used in place of L1 (0.15 g, 0.20 mmol).
Red powder of C9 was collected in a yield of 86% (0.15 g). IR (KBr;
cmꢀ1): 3059 (w), 3026 (w), 2920 (w), 1651 (s), 1624 (s), 1594 (s),
1492 (s), 1492 (m), 1430 (s), 1270 (m), 1180 (m), 1033 (m), 892 (m),
858 (m), 771 (s), 701 (vs). Anal. Calcd for C53H41Cl3N2Ni (870.96): C,
73.09; H, 4.74; N, 3.22. Found: C, 72.92; H, 4.79; N, 3.00.
4.2.3.4. 2,6-Dibenzhydryl-N-(2-(2,4,6-trimethylphenylimino)ace-
naphthylenylidene)-4-chlorobenzenaminonickel dibromide (C4).
The synthetic procedure for C4 was analogous to that for C1, except
that L4 (0.15 g, 0.20 mmol) was used in place of L1 (0.15 g,
0.20 mmol). Red powder of C4 was collected in a yield of 87%
(0.18 g). IR (KBr; cmꢀ1): 3059 (w), 3025 (w), 2919 (w), 1647 (s), 1621
(s), 1584 (s), 1491 (s), 1451 (m), 1427 (s), 1270 (m), 1181 (m), 1076
(m), 1032 (m), 892 (m), 859 (m), 770 (s), 701 (vs). Anal. Calcd for
C53H41ClBr2N2Ni (959.86): C, 66. 32; H, 4.31; N, 2.92. Found: C,
65.97; H, 4.44; N, 2.90.
4.2.3.10. 2,6-Dibenzhydryl-N-(2-(2,6-diethyl-4-methylphenylimino)
acenaphthylenylidne)-4-chlorobenzenaminonickel dichloride (C10).
Using the same procedure as for the synthesis of C6, except that L5
(0.15 g, 0.20 mmol) was in place of L1 (0.15 g, 0.20 mmol), C10 was
obtained as red powder in 77% (0.14 g). IR (KBr; cmꢀ1): 3024 (m),
2968 (m), 1652 (s), 1625 (s), 1589 (s), 1492 (s), 1426 (s), 1291 (m),
1182 (m), 1077 (s), 1032 (m), 920 (m), 827 (s), 771 (s), 701 (vs). Anal.
Calcd for C55H45Cl3N2Ni (899.01): C, 73.48; H, 5.05; N, 3.12. Found:
C, 73.32; H, 5.02; N, 3.00.
4.2.3.5. 2,6-Dibenzhydryl-N-(2-(2,6-diethyl-4-methylphenylimino)
acenaphthylenylidne)-4-chlorobenzenaminonickel dibromide (C5).
Using the same procedure as for the synthesis of C5, except that L5
(0.15 g, 0.20 mmol) was used in place of L1 (0.15 g, 0.20 mmol), C5
was obtained as red powder in 86% (0.26 g). IR (KBr; cmꢀ1): 3025
(m), 2968 (m), 1645 (s), 1619 (s), 1595 (s), 1494 (s), 1428 (s), 1294
(m), 1183 (m), 1079 (s), 1033 (s), 918 (m), 827 (s), 769 (s), 701 (vs).
Anal. Calcd for C55H45ClBr2N2Ni (987.91): C, 66.87; H, 4.59; N, 2.84.
Found: C, 66.65; H, 4.62; N, 2.81.
4.3. X-ray crystallographic studies
Single-crystal X-ray diffraction studies for C1, C3 and C6 were
carried out on a Rigaku RAXIS Rapid IP diffract meter with graphite-
ꢀ
monochromatic Mo K
a
radiation (
l
¼ 0.71073 A). Cell parameters
were obtained by global refinement of the positions of all collected
reflections. Intensities were corrected for Lorentz and polarization
effects and empirical absorption. The structures were solved by
direct methods and refined by full-matrix least-squares on F2. All
non-hydrogen atoms were refined anisotropically. The hydrogen
atoms were placed in calculated positions. Structure solution and
refinement were performed by using the SHELXL-97 package [74].
4.2.3.6. 2,6-Dibenzhydryl-N-(2-(2,6-dimethylphenylimino)acenaph-
thylenylidene)-4-chlorobenzenaminonickel dichloride (C6). The

44
S. Kong et al. / Journal of Organometallic Chemistry 725 (2013) 37e45
Crystal data and processing parameters for C1, C3 and C6 are
Acknowledgments
summarized in Table 6.
This work was supported by the National Natural Science
Foundation of China (No. 20874105) and the President Fund of
GUCAS.
4.4. Ethylene polymerization
4.4.1. Ethylene polymerization under 1 atm ethylene
The pre-catalyst C4 was dissolved in toluene using standard
Schlenk techniques, and the reaction solution was stirred with
a magnetic stir bar under ambient ethylene atmosphere. The
require amount of co-catalyst (MAO) was added by a syringe. After
the reaction was carried out for the required period, the reaction
solution was quenched with 10% hydrochloric acid in ethanol. The
precipitated polymer was collected by filtration, washed with
ethanol and water, and dried in a vacuum at 60 ꢁC until constant
weight.
Appendix A. Supplementary material
CCDC 883744e883746 contain the supplementary crystallo-
graphic data for this paper. These data can be obtained free of
charge from The Cambridge Crystallographic Data Centre via www.
ccdc.cam.ac.uk/data_request/cif.
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Identification code C1
C3
C6
Empirical formula C52H39Br2ClN2Ni C56H47Br2ClN2Ni C52H39Cl3N2Ni
Formula weight
Temperature/K
Wavelength/A
945.83
173(2)
0.71073
Monoclinic
P2(1)/n
15.16(3)
15.983(3)
17.646(4)
90
97.01(3)
90
4243.7(15)
4
1001.94
173(2)
0.71073
Triclinic
P-1
10.721(2)
12.113(2)
19.925(4)
84.22
79.05(3)
81.33(3)
2504.6(9)
2
856.91
173(2)
0.71073
Monoclinic
P2(1)/n
15.144(3)
16.012(3)
17.305(4)
90(3)
97.23(3)
90(3)
4162.6(14)
4
ꢀ
Crystal system
Space group
ꢀ
a/A
ꢀ
b/A
ꢀ
c/A
Alpha/ꢁ
Beta/ꢁ
Gamma/ꢁ
Volume/A
Z
3
ꢀ
D calcd/(g cmꢀ3
m/mmꢀ1
F(000)
)
1.48
2.442
1920
1.329
2.073
1024
1.367
0.698
1776
Crystal size/mm
q
0.37 ꢂ 0.36 ꢂ 0.27 0.41 ꢂ 0.40 ꢂ 0.37 0.22 ꢂ 0.20 ꢂ 0.16
range (ꢁC)
1.72e27.48
ꢀ13 ꢃ h ꢃ 19
ꢀ20 ꢃ k ꢃ 20
ꢀ20 ꢃ l ꢃ 22
18,530
1.04e27.48
ꢀ13 ꢃ h ꢃ 13
ꢀ15 ꢃ k ꢃ 15
ꢀ25 ꢃ l ꢃ 25
22,365
2.71e27.48
ꢀ19 ꢃ h ꢃ 16
ꢀ20 ꢃ k ꢃ 14
ꢀ19 ꢃ l ꢃ 22
18,294
Limiting indices
No. of rflns
collected
No. unique rflns
R(int)
No. of params
Completeness
9591
0.0402
523
11,360
0.0384
559
9420
0.0546
523
98.6%
98.9%
98.6%
to
q [%]
Goodness of
1.16
1.185
1.118
fit on F2
Final R indices
[I > 2 (I)]
R indices (all data) R1 ¼ 0.0741
R1 ¼ 0.0599
R1 ¼ 0.0514
wR2 ¼ 0.1407
R1 ¼ 0.0633
wR2 ¼ 0.1471
0.661
R1 ¼ 0.0852
wR2 ¼ 0.1995
R1 ¼ 0.1063
wR2 ¼ 0.2166
0.360
P
wR2 ¼ 0.1322
wR2 ¼ 0.1429
Largest diff. peak, 0.563
and hole/(e A
ꢀꢀ3
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and ꢀ0.481
and ꢀ0.7904
and ꢀ0.599

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