Structure-property-relationship studies with ethylene polymerization catalysts of Ti, Zr and V containing heterocyclic ligands

Article abstract of DOI:10.1016/j.ica.2015.08.002

21 complexes of bis(benzimidazolyl, benzothiazolyl and benzoxazolyl)methane compounds with Zr(IV), Ti(IV), V(III) metal centers were synthesized, characterized, activated with methylalumoxane (MAO) and then tested for catalytic ethylene polymerization. The activities of the various catalysts were found to be functions of the hetero atoms in the ligand frameworks. The methylene moiety as bridging unit of the two heterocyclic ring systems gave higher catalyst activities than the corresponding 1,2-ethylidene derivatives indicating a strong influence of the bridging unit of the ligand on the catalyst activity. The activity of the catalyst system 10/MAO was investigated with different cocatalyst concentrations. The highest activity was obtained with 23/MAO (573 kg PE/mol cat h). The produced polyethylenes showed high molecular weights (up to 1.77·10⁶ g/mol) and broad molecular weight distributions (up to PD = 64.5). This could result from different interactions of the MAO counterion with the heteroatoms of the catalyst ligand generating different active sites. These catalysts open an easy access to single-reactor multimodal polyethylene technology.

Full text of DOI:10.1016/j.ica.2015.08.002

Accepted Manuscript
Structure-property-relationship studies with ethylene polymerization catalysts
of Ti, Zr and V containing heterocyclic ligands
Hamdi Ali Elagab, Helmut G. Alt
PII:
S0020-1693(15)00385-0
http://dx.doi.org/10.1016/j.ica.2015.08.002
ICA 16633
DOI:
Reference:
To appear in:
Inorganica Chimica Acta
Received Date:
Revised Date:
Accepted Date:
27 May 2015
1 August 2015
3 August 2015
Please cite this article as: H.A. Elagab, H.G. Alt, Structure-property-relationship studies with ethylene
polymerization catalysts of Ti, Zr and V containing heterocyclic ligands, Inorganica Chimica Acta (2015), doi:
http://dx.doi.org/10.1016/j.ica.2015.08.002
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1
Structure-property-relationship studies with ethylene
polymerization catalysts of Ti, Zr and V containing heterocyclic
ligands
[
a]
Hamdi Ali Elagab and Helmut G. Alt*
Keywords:
Complexes with heterocyclic ligands
Ethylene polymerization
Structure-property-relationship
Bimodal resins
Single-reactor technology
_
____________________________________
[
a]
Dr. H. Ali Elagab, Prof. Dr. H. G. Alt
Laboratorium für Anorganische Chemie
Universität Bayreuth
Universitätsstraße 30, 95440 Bayreuth (Germany)
E-mail: helmut.alt@uni-bayreuth.de

2
ABSTRACT
1 complexes of bis(benzimidazolyl, benzothiazolyl and benzoxazolyl)methane compounds
2
with Zr(IV), Ti(IV), V(III) metal centers were synthesized, characterized, activated with
methylalumoxane (MAO) and then tested for catalytic ethylene polymerization. The activities
of the various catalysts were found to be functions of the hetero atoms in the ligand
frameworks. The methylene moiety as bridging unit of the two heterocyclic ring systems
gave higher catalyst activities than the corresponding 1,2-ethylidene derivatives indicating a
strong influence of the bridging unit of the ligand on the catalyst activity. The activity of the
catalyst system 10/MAO was investigated with different cocatalyst concentrations. The
highest activity was obtained with 23/MAO (573 kg PE/mol cat. h). The produced
.
6
polyethylenes showed high molecular weights (up to 1.77 10 g/mol) and broad molecular
weight distributions (up to PD = 64.5). This could result from different interactions of the
MAO counterion with the heteroatoms of the catalyst ligand generating different active sites.
These catalysts open an easy access to single-reactor multimodal polyethylene technology.
1
. Introduction
Recently [1-3] we have shown that benzimidazoles, benzothiazoles and benzoxazoles can
be applied as suitable ligands in titanium, zirconium and vanadium complexes that can be
activated with methyalumoxane (MAO) and then be applied successfully for catalytic
ethylene polymerization [4-6]. In spite of their hetero atoms and the oxophilicity of the
metals, the performances of such catalysts are remarkable. 1,2-Bis-benzimidazoles and 2,6-
bis(benzimidazolyl)pyridine are well known compounds together with their late transition
metal complexes [7-17]. Benzothiazole and benzoxazole contain heterocyclic sulphur and
oxygen atoms and a pseudo imidazole functional group and can act as N-donor ligands with
transition metals [18-24]. Herein we report the first zirconium, titanium and vanadium
complexes of bis(benzimidazolyl, benzothiazolyl, and benzoxazolyl)methane and the
2
importance of the CH bridging unit on the performance of such catalysts in ethylene
polymerization after activation with MAO. Structure-property-relationship studies should
help to design a catalyst with the best performance.
2
. Results and Discussion

3
2
.1. Synthesis of the heterocycles
The condensation reaction of a dicarboxylic acid or an acid anhydride with diamines,
substituted diamines, 2-aminothiophenol, 2-aminophenol and substituted 2-aminophenols in
preheated polyphosphoric acid is a well established procedure for the preparation of the
benzimidazole, benzothiazole and benzoxazole based ligand precursors [25,26] in high
’
yields (Scheme 1). The Philip s modified method was also used for the syntheses of
benzimidazoles based ligand precursors [27, 28].
X
X
2
N
N
R
XH
PPA / 175°C, 3-5h
HOOC
COOH
2
-4H O
2
1
R2
R2
R
NH2
R1
R1
1
2
Compound No.
X
R
R
1
2
3
4
5
6
7
S
NH
NH
NH
O
H
H
H
H
CH
3
H
Cl
H
H
H
O
CH
H
3
H
CH
O
3
Scheme 1. Synthesis of ligand precursors 1-7.
2
2
.2. Synthesis of coordination compounds
.2.1. Synthesis of titanium, zirconium and vanadium complexes
1 13
The complexes were synthesized according to Scheme 2 and characterized by H NMR, C
NMR and mass spectrometry. Table 1 summarizes their spectroscopic data. The titanium and
zirconium complexes were prepared by ligand displacement reactions. After dissolving the
tetrahydrofuran adducts of zirconium and titanium tetrachloride in an appropriate solvent, the
corresponding heterocycle was added and an immediate colour change was observed. The
complexes could be isolated in very high yields (80-95%). The complexes were characterized
by NMR, mass spectrometry and representative examples by elemental analysis. Vanadium

4
complexes were synthesized by dissolving vanadium trichloride in diethyl ether followed by
addition of the ligand precursor with constant stirring over night. The products were obtained
in good yields (70-80%).
X
X
X
X
MCl (THF) , CH Cl
4
2
2
2
N
N
N
N
r. t., 24h
MCl4
R2
R2
R2
R2
R1
R1
R1
R1
M = Ti, Zr
X = NH, S, O
X
X
X
X
VCl3, Et O
2
N
N
N
N
r. t., 24h
VCl3
R2
R2
R2
R2
R1
R1
R1
R1
1
2
Complex No.
X
S
R
R
M
Ti
Zr
V
8
9
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
S
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
S
NH
NH
NH
NH
NH
NH
NH
NH
NH
O
Ti
Zr
V
CH
CH
3
Ti
Zr
V
3
CH
Cl
Cl
Cl
H
3
Ti
Zr
V
Ti
Zr
V
O
H
O
H
O
CH
CH
3
Ti
Zr
V
O
3
O
CH
H
3
O
CH
CH
CH
3
Ti
Zr
V
O
H
3
O
H
3

5
Scheme 2. The synthesized coordination compounds 8-28.
2
.3. Characterization
Since the complexes did not crystallize properly, they were characterized spectroscopically.
1 13
.3.1. H NMR and C NMR spectroscopy:
2
The ligand precursors 1-7 and their titanium and zirconium complexes were characterized
1 13
by H NMR and C NMR spectroscopy. The vanadium complexes, due to their
1
paramagnetism were characterized by mass spectrometry. The H NMR spectrum of
3
compound 1 (Figure 1) shows five sets of resonance signals: a doublet at δ = 8.04 ppm [ JH,H
=
7.8 Hz] is assigned to the two aromatic protons H4, the doublet at δ = 7.95 ppm [d, 2H,
3
3
H,H = 7.8 Hz] is assigned to the aromatic protons H1. At δ = 7.47 ppm a virtual triplet [ JH,H
J
=
7.8 Hz] can be assigned to two protons of the aromatic ring (H2), a virtual triplet at δ =
3
.43 ppm [ JH,H = 7.8 Hz] assigned to two aromatic protons (H3). At δ = 5.05 ppm a singlet
7
corresponds to the protons of the bridging methylene group H5.
1
Figure 1. H NMR spectrum of 1 in DMSO-d
6
.
1
The C NMR spectrum of compound 1 (Figure 2) shows eight resonance signals: at δ =
3
1
67.0 ppm the two carbon atoms C7 appear. The signal at δ = 153.2 ppm is assigned to the
carbon atoms C6. The signal at δ = 135.9 ppm represents the carbon atoms C1. At δ = 127.0
and 125.9 ppm the carbon atoms C4 and C3 appear. The signals at δ = 123.2 ppm and 122.9
ppm can be assigned to C2 and C5, while the signal at δ = 38.5 ppm corresponds to the
2
carbon atom of the bridging CH unit.

6
13
6
Figure 2. C NMR spectrum of 1 in DMSO-d .
1
The H NMR spectrum of complex 9 (Figure 3) shows three sets of signals. The two doublets
at δ = 8.10 and 8.00 ppm can be assigned to H4 and H1. The virtual triplets at δ = 7.53 and
7
2
,45 ppm can be assigned to the protons H2,3, while the protons of the bridging CH group
appear as a singlet at δ = 5.10 ppm.
1
Figure 3. H NMR spectrum of complex 9 in DMSO-d
6
.
1
3
The C NMR spectrum of complex 9 (see Figure 4) shows eight signals: at δ = 167.2,
53.3, 136.0, 127.0, 126.2, 123.4, 123.0 and 38.5 ppm that belong to C1, C7, C2, C5, C4,
C3, C6 and C8.
1

7
1
Figure 4. C NMR spectrum of complex 9 in DMSO-d6.
3
2
.3.2. Mass spectrometry
The mass spectrum of compound 2 shows the molecular ion peak at m/z = 282. (Figure 5).
Figure 5. Mass spectrum of compound 2.
The mass spectrum of complex 9 (Figure 6) does not show the molecular ion peak at m/z =
14 but an incomplete fragmentation pattern and a peak for the free ligand. Complexes with
donor ligands often do not survive the ionisation process without decomposition.
5

8
Figure 6. Mass spectrum of complex 9.
2
.4. Polymerization results
All coordination compounds 8-28 were activated with MAO in toluene solution. The
mechanism should be the same as proposed for the activation of metallocene [29, 30] and 2,
-bis(imino)pyridine iron [31] complexes. The homogeneous catalyst solution was used for
6
ethylene polymerization. The solutions showed variable activities for ethylene polymerization
depending on the coordination sphere of the active centres. The activities are greatly
influenced by the hetero atoms in addition to the ligand environment and the nature of the
coordinated central metal atom. The catalysts generally showed moderate to good activities
compared to the benchmark catalyst Cp
.
2 2
ZrCl [32].
a)
Table 1. Ethylene polymerization activities of complexes 8-28
Complex
No.
Activity
[kg PE/ mol
cat·h]
Polymerization Mw [ g/
PDI
temperature
mol]
Al: M
[
°C]
8
9
279
41
2500:1
2500:1
2500:1
2500:1
1000:1
2500:1
2500:1
2500:1
2500:1
50
50
40
50
50
50
50
50
50
527920
362920
n.d
6.6
4.3
n.d.
11.5
3.0
8.4
5.4
3.2
5.6
b)
9
22
1
1
1
1
1
1
0
0
1
2
3
4
380
493
316
172
173
245
288590
420140
1149590
1906470
424280
466380
c)

9
1
1
1
1
1
2
2
2
2
2
2
2
2
2
5
6
7
8
9
0
1
2
3
4
5
6
7
8
43
2500:1
2500:1
2500:1
2500:1
2500:1
2500:1
2500:1
2500:1
2500:1
2500:1
2500:1
2500:1
2500:1
2500:1
50
50
50
50
50
50
50
50
50
50
50
50
50
50
268280
247000
1770460
n.d.
4.9
3.1
179
148
22
5.3
n.d.
1.8
338
472
424
403
573
145
208
374
138
158
920240
356540
964100
417410
514040
468550
642360
425870
n.d.
3.3
23.1
2.0
5.6
5.4
6.3
64.5
n.d.
19.2
1273130
a) All polymerization reactions were carried out in 250 ml pentane with MAO as
cocatalyst (Al: M = 2500:1) at 50°C, 10 bar ethylene pressure, 1 h reaction time).
b) Reaction temperature 40° C. Other parameters the same.
c) Al: M = 1000: 1. Other parameters the same.
n.d.= not determined
5
4
4
3
3
2
2
1
1
00
50
00
50
00
50
00
50
00
4
72
424
4
03
380
3
16
279
172
173
41
5
0
0
8
11
20
9
12
21
10
13
22
Figure 7. Polymerization activities of the unsubstituted bis(benzothiazolyl) methane (8-10),
bis(benzimidazolyl) methane (11-13) and bis(benzoxazolyl) methane complexes (20-22) after
activation with MAO.

1
0
The activities of the titanium complexes follow the order 20 > 11 > 8, and the activities of the
zirconium complexes show the same trend: 21 > 12 > 9. The vanadium complexes behave
differently with complex 22 having the highest activity: 22 > 10 > 13. The differences in
catalytic activities can be accounted for by the hetero atom effect (S, N, and O) (see Figures 7
and 8).
403
450
400
350
300
250
200
150
100
380
173
50
0
10
13
22
Figure 8: Effect of hetero atoms on the activities of vanadium complexes 10, 13 and 22.
Among the catalyst systems derived from bis(benzimidazolyl) methane, a substituent in meta
position to the imino nitrogen atom influences the catalytic activities of the systems
compared to the unsubstituted ones. The methyl substituted titanium and zirconium
complexes 14 and 15 were more active than the chloro substituted complexes 17 and 18 (see
Figure 9). However, both show lower activities compared to the unsubstituted complexes 11
and 12. The lower activities of the chloro substituted complexes may result from the
interaction of the chloro Lewis base of the substituent with the active centre of a
neighbouring catalyst molecule blocking this active site. On the other hand, for the vanadium
complexes 13, 16 and 19 (Figure 10), the chloro substituted complex 19 shows higher activity
than the unsubstituted complex 13 and the methyl substituted complex 16. This order of
activities may arise from an advantageous electronic effect of the chloro substituent imposed
on the active centre (increase its Lewis acidity) and a weaker oxophilicity of vanadium.

1
1
4
3
3
2
2
1
1
00
50
00
50
00
50
00
3
38
3
16
2
44
179
1
72
173
1
48
4
3
5
0
0
22
11
14
17
12
15
18
13
16
19
Figure 9. Effect of substituents on polymerization activities of bis(benzimidazolyl)methane
complexes 11-19.
400
350
300
250
200
150
100
338
179
173
50
0
13
16
19
Figure 10: Effect of the nature of the substituent on the activity of vanadium complexes 13,
6 and 19.
1
The catalytic activities of complexes derived from 1,1-bis(benzoxazolyl) methane were
affected by the nature and the position of the corresponding substituent [33,34]. The
introduction of a methyl substituent in meta position to the imino nitrogen atoms decreased
the activities of the titanium complex 26, the zirconium complex 27 and the vanadium
complex 28 compared to the unsubstituted complexes 20-22. On the other hand, a methyl

1
2
group para to the imino nitrogen atoms increased the activity of titanium complex 23, while
the activities of the zirconium complex 24 and vanadium complex 25 decreased compared to
the unsubstituted complexes 21 and 22 (see Figure 11).
7
6
5
4
3
2
1
00
00
00
00
00
00
00
0
5
73
472
4
24
4
03
3
74
208
1
58
1
45
1
37
20
23
26
21
24
27
22
25
28
Figure 11. Effect of substituent position on the polymerization activities of the bis
benzoxazolyl) methane complexes 20-28.
(
The activity of the catalyst 10/MAO was tested with different MAO concentrations (Figure
2). At 50°C with an aluminum to vanadium ratio of 1000 : 1, the catalyst shows an activity
1
of 493 [kg PE/mol cat·h]. Increasing the cocatalyst concentration to 2500 equivalents results
in an activity decrease to 379 [kg PE/mol cat·h]. The decrease of activity with increasing
cocatalyst concentration may be explained by the steric effect of the cocatalyst around the
active metal centre slowing down the coordination of the monomer to the metal.

1
3
600
500
400
300
200
100
0
493
380
10/2500:1
10/1000:1
Figure 12: Effect of cocatalyst concentration on the activity of complex 10.
Applying complex 9, the temperature dependence of the polymerization activities was
investigated (Figure 13). Under the same cocatalyst concentration and at a reaction
temperature of 40°C the catalyst system 9/MAO shows an activity of 22.4 [kg PE/mol cat·h].
Increasing the temperature to 50°C lead to an activity of 40.5 [kg PE/mol cat·h]. This
behaviour is in agreement with the fact that kinetics are accelerated with rising temperatures.
41
45
40
35
30
25
20
15
10
5
0
22
9/50°C
9/40°C
Figure 13: Effect of temperature on the activity of complex 9.
GPC analyses of the polyethylenes produced with benzimidazolyl, benzothiazolyl and
benzoxazolyl methane based complexes revealed that the symmetric catalyst systems were
capable to produce resins with moderate to high molecular weights associated with broad
molecular weight distributions. The broad molecular weight distribution may arise from the

1
4
fact that the MAO counterion induces various active sites in the activation process [35] due to
different interactions with the hetero atoms of the catalyst ligand. For example, the catalyst
6
system 17/MAO produced a resin with M
w
= 1.77·10 g/mol (PDI = 5.3) (Figure 14).
Figure 14. GPC profile for polyethylene produced with catalyst 17/MAO.
The GPC profiles of polyethylenes produced with the catalyst 28/MAO (Figure 15) show a
6
molecular weight of M
w
= 1.27·10 g/mol, (PDI = 19.2).

1
5
Figure 15. GPC profile for polyethylene produced with catalyst 17/MAO.
Differential scanning calorimetric (DSC) measurements for representative samples of
polyethylenes produced with 1,1-bis-(benzimidazolyl, benzothiazolyl, and benzoxazolyl)
methane titanium, zirconium and vanadium complexes revealed that the catalyst systems
were capable to produce high density polyethylenes with melting temperatures > 135°C. The
crystallization temperatures of the polymers range from 118-120°C and the polymers have
high degrees of crystallinities (see Table 2). For example, DSC curves for polyethylene
produced with the catalysts 9/MAO and 17/MAO show melting temperatures of 135.6 and
1
38.1°C and crystallization temperatures of 118.3 and 118.1°C. The degrees of crystallinity
are 30.1 and 25.5%.
Table 2. Thermal analysis data representative polymer samples produced with complexes 9,
1
0, 12, 15, 17, 20, 22, 23, 25, 28.

1
6
Complex No.
9
T
m
[°C]
T
cryst [°C]
α [%]
135.6
139.2
137.2
136.5
138.1
135.9
136.1
138.3
135.8
139.4
118.3
119.7
118.8
118.6
118.1
119.1
119.5
119.2
118.7
118.4
30.1
26.7
28.3
27.3
25.5
33.0
31.6
34.4
33.5
32.6
1
1
1
1
2
2
2
2
2
0
2
5
7
0
2
3
5
8
m
T = melting temperature, Tcryst = crystallization temperature, α = degree of crystallinity
Figure 16. DSC curve for polyethylene produced with catalyst 9/MAO.

1
7
Figure 17. DSC curve for polyethylene produced with catalyst 17/MAO.
3
. Experimental
3
.1. General considerations
All experimental work was routinely carried out using Schlenk technique unless
otherwise stated. Anhydrous and purified argon was used as inert gas. n-Pentane,
diethyl ether, toluene and tetrahydrofuran were purified by distillation over Na/K
alloy. Diethyl ether was additionally distilled over lithium aluminum hydride.
Methylene chloride was dried with phosphorus pentoxide and then additionally with
calciumhydride. Methanol and ethanol were dried over molecular sieves. Deuterated solvents
(
3 6
CDCl , DMSO-d ) for NMR spectroscopy were stored over molecular sieves (3Ǻ).
Methylalumoxane (30 % in toluene) was purchased from Crompton (Bergkamen) and
Albemarle (Baton Rouge, USA / Louvain – La Neuve, Belgium). Ethylene (3.0) and
argon (4.8/5.0) were supplied by Rießner Company (Lichtenfels). All other starting
materials were commercially available and were used without further purification. The
titanium and zirconium adducts were synthesized via published procedures [36].
NMR spectroscopy
The spectrometers Varian Inova 300/400 M Hz and Bruker ARX 250 were available
for recording the NMR spectra. The samples were prepared under inert atmosphere
1
argon) and routinely recorded at 25 °C. The chemical shifts in the H NMR spectra
(
3
are referred to the residual proton signal of the solvent (δ = 7.24 ppm for CDCl , δ =

1
8
1
) and in C NMR spectra to the solvent signal (δ = 77.0 ppm
3
2
.5 ppm for DMSO-d
6
for CDCl , δ = 39.5 ppm for DMSO-d
3
6
).
Mass spectrometry
Mass spectra were routinely recorded at the Zentrale Analytik of the University of
Bayreuth with a VARIAN MAT CH-7 instrument (direct inlet, EI, E = 70 eV) and a
VARIAN MAT 8500 spectrometer.
Gel permeation chromatography (GPC)
GPC measurements were routinely performed by SABIC Company (Riyadh, Saudi
Arabia).
Elemental analysis
Elemental analyses were performed with a VarioEl III CHN instrument. Calibration
compound: acetamide.
3
.2. General procedures for the synthesis of the transition metal complexes
Synthesis of organic compounds 1-7
A diamine compound (0.05mol) was mixed with a dicarboxylic acid or an acid anhydride
(
0.025mol) and the mixture was poured in 50 ml of preheated (100°C) polyphosphoric acid.
The mixture was stirred and heated at 175°C for 3-5 hours. The reaction mixture was then
poured into ice cold water and allowed to stand overnight. The precipitate was removed by
filtration and washed several times with diluted sodium hydrogen carbonate solution and
finally with water. The reaction product was then air dried and weighed. The products were
characterized by NMR and mass spectroscopy (Table 4). Representative samples were
characterized by elemental analysis (Table 3).
3
.3. Titanium complexes
4 2
To an amount of 0.87g (2.6 mmol) TiCl (THF) in dichloromethane was added an amount
of 2.6 mmol of the corresponding heterocycle. The reaction mixture was stirred overnight at
room temperature and filtered. The residue was washed several times with dichloromethane
and pentane, dried in vacuo and weighed (80-95%). The products were characterized by

1
9
NMR and mass spectroscopy (Table 4). Representative samples were characterized with
elemental analysis (Table 3).
3
.4. Zirconium complexes
To an amount of 0.45g (1.2mmol) ZrCl
4
2
(THF) in dichloromethane was added an amount
of 1.2 mmol of the corresponding heterocycle. The reaction mixture was stirred overnight at
room temperature and filtered, washed several times with dichloromethane, then with n-
pentane, dried in vacuo and weighed (80-95%). The products were characterized by NMR and
mass spectroscopy (Table 4). Representative samples were characterized with elemental
analysis (Table 3).
3
.5. Vanadium complexes
To an amount of 0.41g (2.6 mmol) VCl
3
in ether was added an amount of 2.6 mmol of the
ligand. The reaction mixture was stirred overnight at room temperature and filtered. The
residue was washed several times with ether and n-pentane, dried in vacuo and weighed (70-
8
0%).The products were characterized by mass spectroscopy and representative samples
were characterized with elemental analysis (Table 3).
Table 3. Elemental analysis data for representative free ligands 1-7 and complexes 8, 10, 13,
1
6, 18, 20, 22, 23, 25, 28.
Compound
Calculated
H
Found
H
No.
1
C
N
C
N
63.8
72.6
73.9
72.0
73.4
38.1
41.0
44.3
47.1
32.8
3.5
9.9
63.6
71.8
73.7
71.8
73.6
37.7
40.8
44.6
46.7
33.2
3.4
4.6
6.0
4.2
5.1
2.3
2.5
3.2
3.9
2.2
10.2
22.4
20.1
11.4
9.8
2
4.8
22.6
20.3
11.2
10.1
5.9
3
5.8
5
4.0
6
5.0
8
2.1
6.2
1
1
1
1
0
3
6
8
2.3
6.4
6.2
3.00
3.7
13.8
12.9
10.2
13.5
13.1
10.0
1.8

m/z [%]
2
0
2
2
2
2
2
0
2
3
5
8
41.1
44.2
43.6
46.9
46.9
2.3
2.5
3.0
3.2
3.2
6.4
6.9
6.0
6.4
6.4
40.7
43.8
43.8
47.1
46.7
2.5
2.3
3.2
2.9
3.0
6.7
7.2
5.8
6.6
6.2
3
.6. Polymerization of ethylene in a 1 litre Büchi autoclave
An amount of 2 – 5 mg of the desired complex was suspended in 5 ml of toluene.
Methylalumoxane (30% in toluene) was added resulting in an immediate colour
change. The mixture was added to a 1 litre Schlenk flask filled with 250 ml n-
pentane. This mixture was transferred to a 1 litre Büchi laboratory autoclave under
inert atmosphere and thermostated. An ethylene pressure of 10 bar was applied for
one hour. The polymer was filtered over a frit, washed with diluted hydrochloric
acid, water, and acetone, and finally dried in vacuo.
Table 4. NMR and mass spectroscopic data of the free ligands 1-7 and complexes 8-28.
1
13
H NMR
C NMR
Mass
Compound No.
δ [ppm]
δ [ppm]
°
+
8
.04(d,2H, J = 7.8 Hz) 167.0, 153.2, 135.9, 282 M (100)
,
7.95(d,2H, J = 7.8
127.0, 125.9, 123.2,
1
Hz) , 7.47(t,2H, J = 7.8122.9, 38.5
Hz) , 7.43(t,2H, J = 7.8
2
Hz) , 5.05(s,2H,CH )
°
+
1
7
7
4
7
7
2.41(s,2H, NH),
150.8, 138.4 122.9,
115.4, 29.8
248 M (100)
.46(m,4H),
2
3
.11(m,4H),
2
.43(s,2H,CH )
°+
.32(d,2H, J = 7.8 Hz),150.6, 139.2 137.9,
.23(s,2H), 6.91(d,2H, 131.2, 123.5, 115.3,
276 M (100)
J = 7.8 Hz),
114.7, 30.0, 21.9
4
.35(s,2H,CH
2
),
)
2.33(s,6H,CH
3

m/z [%]
2
1
1
13
H NMR
C NMR
Mass
Compound No.
δ [ppm]
δ [ppm]
°
+
7.54(s,2H), 7.48(d,2H,
317 M (100)
J = 7.8 Hz), 7.14(d,2H,
J = 7.8 Hz),
4
n.d.
4
7
,
2
.46(s,2H,CH )
°
+
.70(d,2H , J = 7.8 Hz) 159.5, 151.5, 141.3, 250 M (100)
7.50 (d,2H, J= 7.8 125.5, 124.8, 120.4,
5
6
Hz), 7.31(t,4H, J = 7.8 110.9, 29.6
Hz), 4.62(s,2H, CH
2
)
°+
7
.60(d,2H, J = 7.6 Hz), 161.4, 149.5, 141.5, 278 M (100)
.52(s,2H), 7.21(d,2H, 134.7, 126.9, 120.2,
110.9, 29.4, 21.6
7
J = 7.6 Hz) ,
4
2
7
,
.84(s,2H,CH
.41(s,6H, 2CH
.59(d,2H, J = 7.6 Hz) 160.8, 151.5, 139.2, 278 M (100)
7.52(s,2H), 136.0, 126.4, 119.7,
2
),
3
)
°+
7
8
9
7.19(d,2H, J = 7.6 Hz), 111.5, 29.3, 21.9
4
.82(s,2H,CH
.46(s,6H,2CH
.02(d,2H, J = 7.8 Hz), 167.0, 153.2, 135.8, 472 M (2), 436 M -
2
),
2
3
)
°
+
°+
8
°
+
7.92(d,2H, J = 7.8 Hz), 127.0, 125.9, 123.2, Cl (5), 401 M -2Cl
°
+
7.45(t,2H), 7.38(t,2H, 122.9, 38.4
J = 7.8 Hz),
(10), 365 M -3Cl (5),
°+
282 M -TiCl
4
(100)
2
5.02(s,2H,CH )
°+
°+
.10(d,2H, J = 7.8 Hz),167.1, 153.4, 135.9, 517 M (1), 478 M -
8
°
+
8.01(d,2H, J = 7.8 Hz), 127.0, 126.0, 123.3, Cl (10), 444 M -2Cl
°+
7.53(t,2H), 7.45t,2H, J 123.0, 38.5
(20), 406 M -3Cl (5),
°
+
=
7.8 Hz),
282 M -ZrCl
4
(100)
5.10(s,2H,CH )
2
°
+
°+
39 M (2), 402 M -
4
°
+
1
0
n.d.
n.d.
Cl (5), 366 M -2Cl
°
+
(
5), 331 M -3Cl (10),

m/z [%]
2
2
1
13
H NMR
C NMR
Mass
Compound No.
δ [ppm]
δ [ppm]
°
+
2
82 M -VCl
3
(100)
°
+
°+
.52-7.49(m,4H), 7.52-149.0, 135.4, 124.4, 438 M (1), 402 M -
7
7
4
°+
.14(m,4H),
.55(s,2H,CH
115.1, 27.5
Cl (2), 367 M -2Cl
1
1
1
2
°+
2
)
(2), 248 M -TiCl
4
(
100)
°+
°+
.63-7.62(m,4H), 7.33-150.6, 138.7, 122.6, 481 M (1), 444 M -
7
°+
7.30 (m,4H),
115.3, 29.6
Cl (2), 407 M -2Cl
°+
4.91(s,2H,CH
2
)
(1), 370 M -3Cl (2),
°
+
3
36 M -4Cl (1), 248
°
+
M -ZrCl
4
(100)
°
+
°+
06 M (3), 368 M -
4
°
+
Cl (7), 334 M -2Cl
°
+
1
1
1
3
4
5
n.d.
n.d.
(10), 299 M -3Cl
°
+
(
(
20), 248 M -VCl
3
100)
°+
°+
.63(d,2H, J = 8.1 Hz) 146.3, 136.3, 132.3, 466 M (1), 428 M -
7
°
+
,
7.54(s,2H),
130.1, 127.8, 114.3, Cl(5), 393 M -2Cl (5),
°+
7.31(d,2H, J = 8.1 Hz), 114.1, 25.8, 21.8
357 M -3Cl (3), 319
°+
°+
5
.25(s,2H,CH
.42(s,6H,2CH
.55(d,2H, J = 8.1 Hz), 147.5, 135.0, 134.0, 510 M (2), 477 M -
2
),
M -4Cl (2), 276 M -
2
3
)
TiCl (100)
4
°+
°+
7
°+
7
.47(s,2H), 7.21(d,2H, 132.2, 126.7, 114.6, Cl (5), 440 M -2Cl
°
+
J = 8.1 Hz), 5.05
114.3, 26.6, 21.8
(5), 405 M -3Cl (2),
°
+
(
s,2H,CH
2
),
276 M -ZrCl
4
(100)
2.40(s,6H,2CH
3
)
°
+
°+
33 M (2), 397 M -
4
°
+
Cl (5), 360 M -2Cl
1
1
6
7
n.d.
n.d.
°
+
(
10), 324 M -3Cl (5),
°
+
2
3
76 M -VCl (100)
°+
°+
.88(s,2H), 7.80(d,2H, 149.3, 134.7, 132.6, 506 M (3), 470 M -
7
°
+
J = 8.1 Hz), 7.51(d,2H, 129.8, 125.9, 116.5, Cl (2), 434 M -2Cl

m/z [%]
2
3
1
13
H NMR
δ [ppm]
J = 8.1 Hz),
C NMR
δ [ppm]
114.9, 26.9
Mass
Compound No.
°+
(5), 397 M -3Cl (10),
°
+
5
.18(s,2H,CH
2
)
316 M -TiCl
4
(100)
°
+
°+
.89(s,2H, 7.80(d,2H, 149.1, 134.3, 132.2, 549 M (2), 513 M -
7
°
+
J = 8.1 Hz), 7.52(d,2H, 130.1, 126.1, 116.5, Cl (5), 476 M -2Cl
1
1
8
9
°
+
J = 8.1 Hz), 5.23(s,2H, 114.8, 26.7
CH
(10), 440 M -3Cl (5),
°+
2
)
316 M -ZrCl
4
(100)
°
+
°+
73 M (5), 437 M -
4
°
+
Cl (2), 401 M -2Cl
°
+
n.d.
n.d.
(70), 368 M -3Cl
°
+
(
(
10), 316 M -VCl
3
20)
°
+
°+
.69(d,4H, J = 7.8 Hz),161.4, 151.2, 141.3, 438 M (5), 368 M -
7
°
+
7
.36(t,4H, J = 7.8 Hz), 126.1, 125.4, 120.4, 2Cl (10), 331 M -
°
+
2
0
4.85(s,2H,CH
2
)
111.5, 29.3
3Cl(10), 295 M -4Cl
°
+
(
(
5), 250 M -TiCl
4
100)
°
+
°+
.76(d,4H, J = 7.8 Hz),161.78, 151.4, 151.2, 483 M (2), 447 M -
7
°
+
7
.47(t,4H, J = 7.8 Hz), 141.5, 141.1, 126.6, Cl (5), 411 M -2Cl
°
+
2
2
1
2
4.99(s,2H,CH
2
)
126.4, 125.7, 125.6, (5), 375 M -3Cl (10),
°+
1
20.7, 120.6, 111.8, 250 M -ZrCl
4
(100)
29.6
°+
°+
07 M (3), 371 M -
4
°+
Cl (5), 335 M -2Cl
n.d.
n.d.
°
+
(
10), 300 M -3Cl (5),
°
+
2
3
50 M -VCl (100)
7
.61(d,2H, J = 7.6 Hz),161.5, 149.4, 141.5,
.53(s,2H), 7.23(d,2H, 134.8, 127.0, 120.2,
111.0, 29.4, 21.7
°
+
°+
68 M (5), 432 M -
4
7
°+
Cl (2),361 M -3Cl (3),
2
2
3
4
J = 7.6Hz),
°+
2
2
3
96 M -4Cl-2CH (5),
4.84(s,2H,CH
2
),
°+
78 M -TiCl
4
(100)
2
.41(s,6H,2CH
3
)
°+
°+
7.57(d,2H, J = 7.6 Hz),161.4, 149.4, 141.5, 511 M (3), 474 M -

m/z [%]
2
4
1
13
H NMR
δ [ppm]
.51(s,2H),
.20(d,2H,J = 7.6 Hz), 110.9, 29.4, 21.6
.82(s,2H,CH ),
.40(s,6H,2CH
C NMR
Mass
Compound No.
δ [ppm]
°+
7
7
4
2
134.7, 127.0, 120.2, Cl (2), 404 M -3Cl
°+
(1), 340 M -4Cl-2CH
3
°+
2
(3), 278 M -ZrCl
4
3
)
(100)
°
+
°+
35 M (1), 399 M -
4
°
+
Cl (3), 363 M -2Cl
°
+
2
5
n.d.
n.d.
(3), 300 M -3Cl-2CH
3
°
+
(
(
5), 278 M -VCl
3
100)
°
+
°+
.60(d,2H, J = 7.6 Hz),160.8, 151.5, 139.1, 468 M (2), 432 M -
7
°
+
7
.54(s,2H), 7.21(d,2H, 136.1, 126.5, 119.8, Cl (3), 361 M -3Cl
°
+
2
6
J = 7.6Hz),
111.5, 29.3, 21.9
(2), 296 M -4Cl-2CH
3
°
+
4
.82(s,2H,CH
.44(s,6H,2CH
.58(d,2H, J = 7.6 Hz), 160.8, 151.5, 139.1, 511 M (1), 474 M -
2
),
(2), 278 M -TiCl
4
2
3
)
(100)
°+
°+
7
°+
7.52(s,2H), 7.19(d,2H, 136.0, 126.4, 119.7, Cl (3), 404 M -3Cl
J = 7.6 Hz),
°+
2
2
7
8
111.5, 29.3, 21.9
(3), 340 M -4Cl-2CH
3
°+
4.81(s,2H,CH
2
),
(2), 278 M -ZrCl
(100)
4
2.42(s,6H,2CH
3
)
°+
°+
35 M (2), 399 M -
4
Cl (5), 363 M -2Cl
°+
°+
n.d.
n.d.
(3), 300 M -3Cl-2CH
3
°+
(
(
3), 278 M -VCl
100)
3
Solvent = DMSO-d
n.d. = not determined
6
4
. Conclusions
Titanium, zirconium and vanadium chloride complexes containing benzimidazolyl,
benzothiazolyl and benzoxazolyl building blocks are suitable catalyst precursors for ethylene
polymerization inspite of their hetero atoms and the oxophilicity of the metals. When two of
2
these heterocycles are connected via a CH bridge, the two nitrogen atoms of the five
membered heterocycle form a chelating complex with the corresponding metal. It is

2
5
2
surprising that the CH bridge has a very strong influence on the corresponding catalyst
performances compared to other bridging units. Obviously the rigidity of the ligand system is
favourable for catalyst cation and cocatalyst anion interactions. The broad molecular weight
distributions could have their origin from several different active sites that are formed from
different interactions of the cocatalyst anion and the heteroatoms of the catalyst ligands.
These catalyst features open the access to single-reactor multimodal polyethylene technology
with mononuclear complexes.
Acknowledgements
We thank Saudi Basic Industries Corporation (SABIC) for the financial support.
References
[
[
[
[
1] H. A. Elagab, H. G. Alt, Inorgan. Chim. Acta 428 ( 2015) 100-111.
2] H. A. Elagab, H. G. Alt, Eur. Pol. J. 68 (2015) 385-397.
3] H. A. Elagab, H. G. Alt, Inorgan. Chim. Acta 431 (2015) 266-275.
4] W. Kaminsky, M. Fernandes, Polyolefins 2 (2015) 1-16.
[5] C. Redshaw, Y. Tang, Chem. Soc. Rev. 41 (2012) 4484-4510.
[6] M. C. Baier, M. A. Zuideveld, S. Mecking, Angew. Chem. Int. Ed. 53 (2014) 9722-
9
744.
7] A. B. P. Lever, B. S. Ramaswamy, S. H. Simonsen, L. K. Thompson, Can. J. Chem.,
8 (1970) 3076-3088.
[
4
[8] S. Wang, Y. Cui, R. Tan, Q. Luo, J. Shi, Q. Wu, Polyhedron 11 (1994) 1661-1668.
[9] J. Wang, Y. Zhu, S. Wang, Y. Gao, Q. Shi, Polyhedron 13( 1994) 1405-1409.
[
[
10] R. C. Holz, L.C. Thomson, Inorg. Chem., 27 (1988) 4640-4644.
11] S. X. Wang, Y. Zhu, F. G. Zhang, Q.Y. Wang, L. F. Wang, Polyhedron 11 (1992)
1
909-1915.
[
[
12 A. W. Addison, S. Burman, C. B. Wahlgren, O. A. Raijan, T. M. Rowe, E. Sinn, J.
Chem. Soc., Dalton Trans. (1987), 2621-2630.
13] S. Ruttimann, C. M. Moreau, A. F. Williams, G. Bernardinelli, A. W. Addison,
Polyhedron 11 (1992) 635-646.
[
[
14] S. M. Nelson, F. S. Esho, M. G. B. Drew, J. Chem. Soc., Dalton Trans. (1982) 407-415.
15] N. Shashikala, V. Gayathri, N. M. N. Gowda, G.K.N. Reddy, J. Indian Chem. Soc.

2
6
6
6 (1989) 537-540.
[
[
16] S. B. Sanni, H. J. Behm, P. T. Beurskens, G.A.V. Albada, J. Reedijk, A.T.H. Lenstra,
A. W. Addison, M.J. Palaniandavar, J. Chem. Soc., Dalton Trans. (1988) 1429-1435.
17] G. C. Wellon, D. V. Bautista, L.K. Thompson, F.W. Hartstock, Inorg. Chim. Acta.
75 (1983) 271-276.
[
[
[
[
[
18] H. G. Bheemanna, V. Gayathri, N. M. N. Gowda, J. Appl. Chem. 7 (2014) 17-22.
19] J. C. T. Rendell, L. K. Thompson, Can. J. Chem. 57 (1979) 1-4.
20] L. K. Thompson, J. C. T. Rendell, G. C. Wellon, Can. J. Chem. 60 (1982) 514.
21] E. J. Duff, M. N. Hughes, K. J. Rutt, J. Chem. Soc., A (1969), 2101-2105.
22] M. J. M. Campell, D. W. Card, R. Grzeskowiak, M. Goldstein, J. Chem. Soc., A
(1970) 672-675.
[
[
[
[
[
[
23] N. N. Y. Chan, M. Goodgame, M. J. Weeks, J. Chem. Soc., A (1968) 2499-2501.
24] L. K. Thompson, R. G. Ball, J. Trotter, J. Can. J. Chem. 58 (1980) 1566-1576.
25] L. Wang, M. M. Joullie, J. Am. Chem. Soc. 79 (1957) 5706-5708.
26] C. Rai, J. B. Braunwarth, J. Org. Chem. 26 (1961) 3434-3436.
27] M. A. Phillips, J. Chem. Soc. (1928) 2393.
28] C. J. Matthews, W. Clegg, M. R. J. Elsegood, T. A. Leese, D. Thorp, P. Thornton, J. C.
Lockhart, J. Chem. Soc., Dalton Trans. (1996) 1531-1538.
[
[
29] M. Bochmann, L. M. Wilson, J. Chem. Soc. Chem. Commun. 21 (1986) 1610-1611.
30] F. Jordan, C. S. Bajgur, W. E. Dasher, A. L. Rheingold, Organometallics 6 (1987)
1
041.
31] M. Seitz, W. Milius, H. G. Alt, J. Mol. Catal. A 261 (2007) 246-253.
32] H. G. Alt, A. Köppl, Chem. Rev. 100 (2000)1205-1221.
[
{
[
[
[
[
33] H. A. Elagab, H. G. Alt. Jordan Journal of Chemistry 10 (2015) 1-19.
34] H. A. Elagab, H. G. Alt. Jordan Journal of Chemistry 10 (2015) 41-57.
35] H. G. Alt, R. Ernst, J. Mol. Catal. A 195 (2003) 11-27.
36] L. E. Manzer, Inorg. Synth. 21 (1982) 135-140.

2
7
Graphical Abstract Hamdi5
Complexes of Ti, Zr, and V with heterocyclic ligands can be activated with methylalumoxane
MAO) and applied for catalytic ethylene polymerization. The produced polyolefins have
high molecular weights and broad molecular weight distributions.
(
X
X
X
X
MCl (THF) , CH Cl
4
2
2
2
N
N
N
N
r. t., 24h
MCl4
R2
R2
R2
R2
R1
R1
R1
R1
M = Ti, Zr
X = NH, S, O
X
X
X
X
VCl3, Et O
2
N
N
N
N
r. t., 24h
VCl3
R2
R2
R2
R2
R1
R1
R1
R1

2
8
Highlights Hamdi 5
-
-
-
-
-
Ti, Zr and V complexes with heterocyclic chelating ligands
Catalytic ethylene polymerization
Influence of the bridge
Bimodal and multimodal resins
Single-reactor polyethylene technology