Bis(benzimidazolyl, benzothiazolyl, and benzoxazolyl)benzene complexes as catalysts for ethylene polymerization

Article abstract of DOI:10.1016/j.ica.2015.01.026

A series of 36 complexes of 1,2-bis(benzimidazolyl, benzothiazolyl and benzoxazolyl)benzene compounds with Ti(IV), Zr(IV) and V(III) were synthesized and characterized. After activation with methylaluminoxane (MAO), they showed variable activities towards ethylene polymerization. Parameters like the steric conditions and the number and nature of the hetero atoms at the precatalyst molecule, the concentration of the cocatalyst MAO, the nature of the transition metal and the reaction temperature have a strong influence on the performance of the corresponding catalysts. The polymerization activity of the catalyst system [1,2-bis(benzimidazolyl)benzene zirconium tetrachloride] 20/MAO was investigated under various polymerization conditions. Studies of structure-property relationships allowed the optimization of catalysts. Bimodal or multimodal resins indicate the existence of more than one active site in the polymerization reaction in one type of homogeneous catalyst.

Full text of DOI:10.1016/j.ica.2015.01.026

Accepted Manuscript
Bis (benzimidazolyl, benzothiazolyl, and benzoxazolyl) benzene complexes as
catalysts for ethylene polymerization
Hamdi Ali Elagab, Helmut G. Alt
PII:
S0020-1693(15)00033-X
http://dx.doi.org/10.1016/j.ica.2015.01.026
ICA 16380
DOI:
Reference:
Inorganica Chimica Acta
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Received Date:
Revised Date:
Accepted Date:
28 November 2014
20 January 2015
21 January 2015
Please cite this article as: H.A. Elagab, H.G. Alt, Bis (benzimidazolyl, benzothiazolyl, and benzoxazolyl) benzene
complexes as catalysts for ethylene polymerization, Inorganica Chimica Acta (2015), doi: http://dx.doi.org/10.1016/
j.ica.2015.01.026
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1
Bis (benzimidazolyl, benzothiazolyl, and benzoxazolyl) benzene
complexes as catalysts for ethylene polymerization
Hamdi Ali Elagab, Helmut G. Alt*
Laboratorium für Anorganische Chemie, Universität Bayreuth,
Postfach 10 12 51, D-95440 Bayreuth
Received:
Corresponding author. Tel.: +49 921 43864
E-mail address: helmut.alt@uni-bayreuth.de (H.G. Alt)

2
Abstract
series of 36 complexes of 1,2-bis(benzimidazolyl, benzothiazolyl and
A
benzoxazolyl)benzene compounds with Ti(IV), Zr(IV) and V(III) were synthesized and
characterized. After activation with methylaluminoxane (MAO), they showed variable
activities towards ethylene polymerization. Parameters like the steric conditions and the
number and nature of the hetero atoms at the precatalyst molecule, the concentration of the
cocatalyst MAO, the nature of the transition metal and the reaction temperature have a strong
influence on the performance of the corresponding catalysts. The polymerization activity of
the catalyst system [1,2-bis(benzimidazolyl)benzene zirconium tetrachloride] 20/MAO was
investigated under various polymerization conditions. Studies of structure property
relationships allowed the optimization of catalysts. Bimodal or multimodal resins indicate the
existence of more than one active site in the polymerization reaction in one type of
homogeneous catalyst.
Keywords: Bis(benzimidazole, benzothiazole, benzoxazole) complexes; Homogeneous ethylene polymerization;
Bimodal resins
1. Introduction
An important trend in catalytic olefin polymerization is to improve catalysts regarding their
tolerance against reaction impurities, to produce tailored polyolefins with special properties
and to escape from restrictions of existing patent claims. In this context the application of
ligands with hetero atoms like nitrogen, oxygen, sulphur, phosphorus and others, can play an
important role in research and technology [1-6 and references therein]. Imidazole can act as a
typical heterocyclic ligand with nitrogen as donor atom. It is also a component of biologically

3
important molecules [7]. Because of these aspects, the coordination chemistry of related
ligands has been the subject of numerous investigations [5-7 and references therein]. The
coordination behaviour of chelating benzimidazole type ligands has been studied by several
research groups, some of them with an interest in mimicking biological activities [8-12]. 1,2-
Bis-benzimidazoles and 2,6-bis(benzimidazolyl)pyridine are well known ligands for late
transition metal complexes [13-23] and an increasing interest has been focused on the
exploration and development of homogeneous transition metal catalysts for olefin
polymerization as a result of a permanently growing demand for polyolefin resins [24-26].
For catalytic ethylene polymerization, only 1,2-bis (benzimidazolyl)-benzene copper(II)
complexes were reported [27]. The vanadium complexes of bis(benzimidazole)amine
tridentate ligands [N, N, N], were reported as active ethylene polymerization catalyst
precursors [28]. After activation with alkylaluminum compounds [28], 2,6-bis(2-
benzimidazolyl)pyridine zirconium dichloride / MAO polymerizes methylacrylate [29].
Herein, we report the first titanium, zirconium and vanadium complexes of 1,2-
bis(benzimidazolyl, benzothiazolyl, benzoxazolyl)benzene, 2,6-bis(benzothiazolyl and
benzoxazolyl)pyridine. Their behaviour towards ethylene polymerization after activation with
methylaluminoxane (MAO) was investigated.
2. Results and Discussion
2.1. General synthesis of the ligand precursors
The condensation reaction of a dicarboxylic acid or an acid anhydride in preheated
polyphosphoric acid is a well established procedure for the preparation of imidazole based
compounds [30, 31] in high yields (Scheme 1)

4
R3
X
X
O
R3
R2
N
N
XH
NH
PPA / 175°C, 3-5h
-3H2O
O
2
R1
2
R2
R2
O
R1
R1
Compound No.
X
S
S
NH
NH
NH
NH
NH
NH
O
R1
R2
H
H
H
H
H
H
H
R3
H
CH3
H
H
H
CH3
CH3
CH3
H
H
H
H
CH3
Cl
H
1
2
3
4
5
6
7
8
CH3
Cl
H
H
H
9
O
CH3
H
H
H
10
11
12
O
CH3
H
H
O
H
CH3
Scheme 1. Synthesis of compounds 1-12.
2.2. Synthesis of coordination compounds
2.2.1 Synthesis of the titanium and zirconium complexes
1
The complexes were synthesized according to Scheme 2 and characterized by H and 13C
NMR spectroscopy and mass spectroscopy (Table 1). The titanium and zirconium complexes
were prepared by ligand displacement reactions. The reaction of the tetrahydrofuran adducts
of titanium and zirconium tetrachloride with the corresponding ligand precursor in methylene

5
chloride resulted in an immediate color change and the complexes could be isolated in very
high yields (80-95 %). The complexes were characterized by NMR, mass spectrometry and
elemental analysis.
2.2.2 Synthesis of the vanadium complexes
The vanadium complexes were synthesized by dissolving vanadium trichloride in diethyl
ether followed by the addition of the ligand precursor with constant stirring overnight. The
product yields were 60-78 % (see Scheme 2).
R3
R3
1- MCl4(THF)2, CH Cl2
2
X
X
X
X
2- MCl3, Et2O
r. t., 24h
N
N
N
N
MCln
R2
R2
R2
R2
1-M =Ti, Zr
2-M = V
R1
R1
R1
R1
Complex No.
X
R1
R2
R3
M
S
S
S
S
S
S
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
CH3
CH3
CH3
H
Ti
Zr
V
Ti
Zr
V
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
H
H
H
NH
NH
NH
NH
NH
NH
NH
NH
NH
NH
NH
NH
NH
NH
NH
NH
H
H
Ti
Zr
V
Ti
Zr
V
H
H
H
H
CH3
CH3
CH3
Cl
Cl
Cl
H
H
H
CH3
CH3
CH3
Cl
H
H
H
H
H
CH3
CH3
CH3
CH3
CH3
CH3
CH3
Ti
Zr
V
Ti
Zr
V
Ti
Zr
V
Ti

6
NH
NH
O
O
O
Cl
Cl
H
H
H
CH3
CH3
CH3
H
H
H
H
H
H
CH3
CH3
H
H
H
Zr
V
Ti
Zr
V
Ti
Zr
V
35
36
37
38
39
40
41
42
43
44
45
46
47
48
O
H
H
O
O
H
H
H
H
O
O
CH3
CH3
CH3
H
H
H
Ti
Zr
V
Ti
Zr
V
H
O
O
H
H
H
CH3
CH3
CH3
O
O
H
H
H
H
Scheme 2. Synthesis of the coordination compounds 13-48.
2.3. Characterization
2.3.1. 1H and 13C NMR spectroscopy
Compounds 1-12 and their titanium and zirconium complexes were characterized by 1H and
13C NMR spectroscopy. The vanadium complexes, due to their paramagnetism, were
characterized by mass spectroscopy.
The 1H NMR spectrum of compound 1 (see Figure 1) shows six sets of resonance signals for
the 12 protons because of the symmetry of the molecule. The doublet with an unresolved long
range coupling at δ = 8.01 ppm [3JH,H = 7.6 Hz] can be assigned to the two protons of the
benzothiazole phenyl rings H6. In a similar manner H3 appears as a doublet at δ = 7.76 ppm
[3JH,H = 7.6 Hz]. The protons in positions 2 and 1 of the bridging phenylene ring appear as an
AA´BB´ pattern at δ = 7.93 and 7.58 ppm. At δ = 7.44 [JH,H = 7.6 and 1.7 Hz] and δ = 7.33
ppm [JH,H = 7.6 and 1.7 Hz] doubles of doublets are observed for H5 and H4.

7
Figure 1. 1H NMR spectrum of compound 1 in CDCl3 .
The 13C NMR spectrum for compound 1 (Figure 2) shows ten resonance signals each
equivalent to 2 carbon atoms: The quaternary carbon atoms C4, C10, C5 and C3 appear at δ
= 166.4, 153.4, 136.6 and 131.6 ppm. The carbon atoms in positions 1 and 2 of the bridging
phenylene group are observed at δ = 131.6 and 131.5 ppm. C8, C7, C9 and C6 can be
detected at δ = 127.2 , 126.3, 123.8 and 121.9 ppm.
Figure 2. 13C NMR spectrum of compound 1 in CDCl3

8
1
The H NMR spectrum of complex 14 (Figure 3) shows five sets of resonance signals. The
doublet at δ = 8.01 ppm [2H, JH,H = 7.8 Hz] can be assigned to the protons H6 and the
multiplet at δ = 7.92-7.90 ppm can be assigned to the protons H2 and H3. A double of
doublets at δ = 7.72 ppm [JH,H = 4.7 and 3.1 Hz] is assigned to the protons H1. The protons
H4 and H5 appear as virtual triplets at δ = 7.45 [3JH,H = 7.8 Hz] and 7.38 ppm [3JH,H = 7.8
Hz] and they show unresolved long range couplings in the order of about 0,2 Hz.
Figure 3. 1H NMR spectrum of complex 14 in CDCl3
The 13C NMR spectrum of complex 14 (Figure 4) shows ten resonance signals each
corresponding to two carbon atoms. The quaternary carbon atoms C4, C10, C5 and C3 show
signals at δ = 166.4, 153.4, 136.6 and 133.5 ppm. C1 and C2 of the 1,2-phenylene bridge
appear at δ = 131.6 and 131.5 ppm. The signals at δ = 127.2 and 126.3 ppm can be assigned
to C7 and C8, signals at δ = 123.8 and 122.9 ppm to C9 and C6.
Figure 4. 13C NMR spectrum of complex 14 in CDCl3

9
2.3.2. Mass spectrometry:
The mass spectrum of compound 1 is shown in Figure 5. The molecular ion peak is detected
at m/z = 344; the loss of a SH group results in an ion at m/z = 311. The ion at m/z = 278
corresponds to the loss of two SH groups and the peak with m/z = 222 is assigned to M°+-
C6H4NS. The ion with m/z = 108 stems from the fragment C6H4S+.
Figure 5. Mass spectrum of compound 1.
The mass spectrum of complex 14 (see Figure 6) shows a base peak at m/z = 344
representing the mass of the free ligand. Peaks of weak intensities at m/z = 578-582 could
derive from a protonated molecular ion but they are not specific. Generally, it can be
observed that the weak dative bonds involved in the formation of the complexes are
responsible for the relatively low peak intensities in the fragmentation pattern.

10
Figure 6. Mass spectrum of complex 14.
Polymerization results
The complexes of titanium, zirconium and vanadium with ligands derived from 1,2-
bis(benzimidazolyl)benzene, 1,2-bis(benzothiazolyl)benzene and 1,2-bis(benzoxazolyl)-
benzene compounds were activated with methylalumoxane (MAO) in toluene solution
assuming a mechanism as proposed for the activation of metallocene [32,33] and 2,6-
bis(imino)pyridine iron (II) [34] compounds The corresponding homogeneous catalyst
solution was used for ethylene polymerization.
Table 1. Ethylene polymerization activitiesa) of complexes 13-48
Complex No.
Activity
[kg PE/ mol cat.h]
219.50
131.57
442.11
13
14
15

11
260.42
127.74
241.40
252.42
285.50
404.80
202.40
66.50
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
307.70
35.70
122.50
165.00
88.30
131.60
105.75
314.80
120.48
103.75
203.50
132.40
69.60
354.90
113.82
260.70
401.52
87.92
391.30
110.10
73.60
166.67
175.82
147.90
26.55
a) All polymerization reactions were carried out in 250 ml pentane with MAO as cocatalyst
(Al: M = 2500:1) at 50°C and 10 bar ethylene pressure, 1h).
The catalysts showed various activities for ethylene polymerization under different
polymerization conditions (co-catalyst concentration, polymerization temperature). The
activities are greatly influenced by the hetero atoms in addition to the ligand environment and
the nature of the central metal atom (see Figure 7).

12
500
450
400
350
300
250
200
150
100
50
442.1
404.8
354.9
285.5
260.7
252.4
219.5
131.6
113.8
0
13
14
15
19
20
21
37
38
39
Figure 7. Polymerization activities of catalysts 13-15, 19-21 and 37-39.
The activities of titanium complexes follow the order 37 > 19 > 13, the activities of the
zirconium complexes show the order 20 > 14 > 38. The vanadium complexes behave in a
reversed order compared to the titanium complexes as follows 15 > 21 > 39. The activities
can be compared with similar complexes in the literature [35,36]. The differences in the
catalytic activities can be accounted for by the hetero atom effect (S, N, and O). Among the
catalyst systems derived from 1,2-bis(benzimidazolyl)benzene, 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 complexes 22-24 were more active than the chloro
substituted complexes 25-27 (see Figure 8). However, both show

13
450
400
350
300
250
200
150
100
50
404.8
307.7
285.5
252.4
202.4
165
122.5
66.5
35.7
0
19
20
21
22
23
24
25
26
27
Figure 8. Activities of 1,2-bis(benzimidazolyl)benzene complexes 19-27.
lower activities compared to the unsubstituted complexes 19-21. The lower activities of the
chloro substituted complexes 25-27 may result from the interaction of the Lewis base (chloro
substituent) with the active center of a neighbouring catalyst molecule.
The catalytic activities of complexes 37-45 derived from 1,2-bis(benzoxazolyl)benzene were
affected by both substitution pattern and type. The introduction of methyl substituents in meta
position to the imino nitrogen atoms increased the activities of the complexes 40 (Ti) and 42
(V) compared to the unsubstituted complexes 37 and 39, while the activity of the zirconium
complex 41 decreases compared to complex 38. On the other hand, a methyl group para to
the imino nitrogen atoms decreased the activities of complexes 43-45 (see Figure 9). The
lower activities of 22 – 27/MAO compared to some of the unsubstituted derivatives 13-
21/MAO could be due to different concentrations of active sites.

14
450
400
350
300
250
200
150
100
50
401.5
391.3
354.9
260.7
166.7
113.8
110.1
87.9
73.6
0
37
38
39
40
41
42
43
44
45
Figure 9. Activities of 1,2-bis(benzoxazolyl)benzene complexes 37-45.
Catalyst No.Temperature
°C
M:Al
Activity
Mn
Mw
[g / mol]
PD
[kg PE/mol [g / mol]
cat.h]
13
13
14
14
14
15
15
20
20
20
20
20
20
50
40
40
50
20
50
20
40
50
60
80
1:2500
1:2500
1:1000
1:2500
1:2500
1:1000
1:2500
1:2500
1:2500
1:2500
1:2500
1:2500
861
219
1311
450
131
54
3468
n.d.
1512260
n.d.
436
n.d
9.2
n.d
n.d
3.0
n.d
693
248
n.d
233
n.d
1371582
n.d.
n.d.
149349
n.d.
n.d.
458223
n.d.
1389040
n.d.
442
116
225
285
227
191
1832
4734
n.d.
1271018
1177503
n.d.
4356
n.d.
972211
n.d.
n.d. = not determined
Table 2. Effect of temperature and cocatalyst concentration on the activities and polymer
properties of polyethylene produced with complexes 13-15 and 20.

15
The activity of the catalyst system 20/MAO (see Table 2) was tested at different
temperatures. At 20°C the catalyst shows an activity of 116 [kg PE/mol cat.h]. Increasing the
temperature to 50°C results in an activity increase to 285 [kg PE/mol cat.h]. A further
increase of the temperature results in an activity decrease to 191 [kg PE/mol cat.h]. The
decrease of activity with rising temperature may be explained by the deactivation of some
active centres [37] as a consequence of thermal decomposition of the original catalyst [38,39]
(Figure 10).
300
250
200
150
100
50
0
0
20
40
60
80
100
temperature (°C)
Figure 10. Effect of temperature on polymerization activity of catalyst 20/MAO.
Applying complexes 13 and 15, the temperature dependence of polymerization activities was
investigated (Table 2). Under the same polymerization conditions (cocatalyst concentration
and reaction temperature), the titanium complex showed a higher activity at low temperature
while the vanadium complex showed a higher activity at elevated temperatures (Figure 11).

16
900
800
700
600
500
400
300
200
100
0
851
442.1
219
54.3
13/20°C
13/50°C
15/20°C
15/50°C
.
Figure 11. Effect of temperature on activities of catalysts 13, 15/MAO.
GPC analyses of the polyethylenes produced with benzimidazole based complexes revealed
that the symmetric catalyst systems were capable to produce resins with very high molecular
weights associated with broad or bimodal molecular weight distributions (Table 2). The
bimodality may arise from the fact that the MAO counterion induces the necessary
dissymmetry of the active sites in the activation process [40]. For example, the catalyst
system 13/MAO produced a resin with Mw= 1512260 g/mol in a bimodal fashion (PD = 436)
(see Figure 12).

17
Figure 12. HT-GPC data of polyethylene produced with 13/MAO.
Figures 13 and 14 show the GPC spectra of polyethylenes produced with the catalysts
14/MAO and 15/MAO. The molecular weights Mw of the polymers produced with 14/MAO
and 15/MAO were 1371582 g/mol, (PD= 9.18) and 1389040 g/mol (PD= 3.03).
Figure 13. HT-GPC data of polyethylene produced with 14/MAO.
Figure 14. HT-GPC data of polyethylene produced with 15 /MAO.

18
The effect of the polymerization temperature on both molecular weights and polydispersities
of the polymers produced with the catalyst 20/MAO was investigated. At 20°C (Figure 15)
the molecular weight Mw was 1271018 g/mol, and the polydispersity index PDI = 693.
Figure 15. HT- GPC data of polyethylene produced with 20/MAO.
At 40° C a resin with Mw = 1177503g/mol and PD = 248 was obtained. Increasing the
polymerization temperature to 60°C both the molecular weight (Mw = 972211g/mol) and the
polydispersity (PD = 223) decreased. The high molecular weight resins and the decrease of
the molecular weight with increasing polymerization temperature suggest that the rate of the
propagation reactions (the activation barrier for propagation is usually low if existent at all) is
much faster at lower temperatures than the rate of termination (the termination reactions are
subjected to activation barriers).This effect is pronounced in the polydispersity index. The
higher the temperature, the lower the polydispersity (Table 2).
DSC measurements showed that the catalyst systems produced HDPE with a high degree of
crystallinity. For example, the melting and crystallization temperatures of the polyethylene
produced with the catalyst system 33/MAO were 139.3 and 121.2°C and the degree of
crystallinity α= 36% (see Figure 16).

19
Table 3. Thermal analysis data for representative polymer samples.
Complex
No.
14
Tm
°C
Tx
°C
α
%
33
27
38
33
25
36
23
134
137
138
137
136
139
136
118
119
118
120
121
121
120
17
20
21
24
33
36
Figure 16. DSC curves of polyethylene produced with the catalyst 33/MAO.

20
3. Experimental
All experimental work was routinely carried out using Schlenk technique unless
otherwise stated. Dried 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 aluminium hydride. Methylene
chloride was dried with phosphorus pentoxide and calcium hydride. Methanol was
dehydrated over magnesium, ethanol over sodium. Deuterated solvents (CDCl3, DMSO)
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 [41].
3.1 NMR spectroscopy
The spectrometers Varian Inova 300/400 MHz and Bruker ARX 250 MHz 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
are referred to the residual proton signal of the solvent (δ = 7.24 ppm for CDCl3, δ =
2.5 ppm for DMSO) and in 13C NMR spectra to the solvent signal (δ = 77.0 ppm for
CDCl3, δ = 39.5 ppm for DMSO).

21
Table 4. NMR and mass spectroscopic data of ligand precursors 1-12 and complexes 13-48.
1H NMR
δ [ppm]
8.01(d,2H), 7.92-
7.90(dd,2H), 7.76(d,2H), 133.5, 131.6, 131.5,
7.61-7.58(dd,2H),
13C NMR
Mass
m/z[%]
Compound No.
1a
δ [ppm]
166.4, 153.436, 136.6, 344M°+(100)
127.2, 126.3, 123.8,
121.9
7.44(t,2H), 7.33(t,2H)
8.01-7.95(m,2H), 7.84- 166.6, 166.5, 153.6, 358M°+(100)
7.79(m,3H), 7.74(s,1H), 153.5, 141.1, 136.8,
7.48-7.44(m,3H), 7.38- 136.8, 133.5, 131.8,
7.33(m,2H), 2.50(s,3H, 131.2, 131.1, 131.0,
2
3
CH3)
126.3, 126.2, 125.5,
125.4, 123.6, 123.5,
121.7, 121.6, 21.3
7.88(d,1H), 7.80(d,1H), 151.6, 137.9, 133.5, 310 M°+ (100)
7.69(t,2H), 7.64(s,2H, N- 131.9, 129.4, 123.5,
H), 7.62-7.59(m,4H),
7.27-7.25(m,4H),
115.5
8.05(s,2H), 7.78(s,2H,N- 151.6, 139.0, 137.8, 338 M°+ (100)
H), 7.63(s,2H), 132.2, 132.0, 130.4,
7.56(d,2H), 7.35(s,2H), 129.9, 115.9, 115.1,
4
5
7.00(d,2H),
2.37(s,6H,CH3)
22.0
8.14 (s,2H), 7.61 (s,4H), 154.3, 141.4, 138.9, 378 M°+ (100)
7.55 (d,2H), 7.12(d,2H) 132.1, 130.4, 130.3,
126.6, 122.4, 117.1,
115.8
152.1,152.0,140.3,
9.67 (s,2H,N-H),
324 M°+ (100)
7.97(d,1H), 7.92(s,1H), 132.6, 132.5, 131.1,
7.56-7.51(m,4H),
7.47(d,1H), 7,18-
7.15(m,4H),
131.0 129.9, 127.3,
122.8, 122.7, 115.2,
21.5
6
2.40(s;3H,CH2)
7.96(d,1H), 7.91(s,1H), 151.7,151.6,140.1,
7.44-7.43(m,3H), 132.5, 132.2, 132.1,
7.35(s,2H), 6.98(d,2H), 132.0, 131.0, 129.7,
352 M°+ (100)
2.42(s,3H,CH3),
2.36(s,6H,2CH3)
127.2, 124.3, 124.2,
116.3, 115.5, 22.0,
21.4
7
8
8.10-8.08(d,1H), 155.0,155.1,
8.04(s,1H), 7.62 (d,2H), 141.7,141.6,
393 M°+ (100)

22
1H NMR
δ [ppm]
7.56-7.53(m,2H),
13C NMR
Mass
m/z[%]
Compound No.
δ [ppm]
139.2,139.1,
7.34(d,1H), 7.10(d,2H), 132.5,132.1,
130.8,130.3,
2.38(s,3H,CH3)
127.6,126.3,126.2
122.2,122.1
117.0,116.9,
115.7,115.6, 21.4
8.07(t,2H), 7.81(t,2H), 162.2, 151.0, 141.9, 312M°+(100)
7.77(t,2H), 7.53(d,2H), 132.5, 131.7, 127.4,
9
7.34(d,4H)
126.5, 125.5, 120.7,
111.5
8.130(t,2H), 7.84(d,2H), 162.3, 149.4, 142.2, 340M°+(100)
7.52(s,2H), 7.44(d,2H), 134.9, 132.4, 131.6,
10
11
7.19(d,2H),
2.40(s,6H,2CH3)
8.12-8.09(m,2H), 7.85- 161.8, 151.4, 139.8, 340M°+(100)
7.82(m,2H), 7.60(d,2H), 136.5, 132.3, 131.7,
7.37(s,2H), 7.20(d,2H), 127.5, 126.7, 120.2,
127.6, 127.4, 120.5,
110.9, 21.6
2.41(s,6H, 2CH3)
111.4, 21.9
7.97(d,1H), 7.89(s,1H), 162.7, 162.6, 151.2, 326M°+(100)
7.64(d,2H), 7.59(d,1H), 151.1, 142.2, 142.1,
7.49(d,2H), 7.31(t,4H), 142.1, 132.1, 131.9,
12
2.37(s,3H,CH3)
131.19, 127.5, 125.5,
125.4, 124.9, 124.6,
124.5, 120.4, 120.2,
110.7, 110.6, 21.4
8.06(d,2H), 7.97-
7.94(m,4H), 7.77-
166.4, 153.4, 136.6, 534 M°+(3), 498 M°+-
133.5, 131.7, 131.62, Cl (2), 463M°+-2Cl (2),
13
14
15
7.74(dd,2H), 7.50(t,2H), 127.3, 126.4, 123.8, 427 M°+-3Cl (1), 344
7.47-7.40(t,2H)
8.02-7.99 (d,2H), 7.92- 166.4, 153.4, 136.6, 577 M°+(1), 506 M°+-
7.89(m,4H), 7.72-
133.5, 131.6, 131.5, 2Cl (3), 470M°+-3Cl
7.70(dd,2H), 7.44(t,2H), 127.2, 126.3, 123.8, (2), 433 M°+-4Cl (5),
123.0
M°+-TiCl4 (100)
7.38(t,2H)
122.9
344 M°+-ZrCl4 (100)
501M°+(1), 465 M°+-Cl
(3), 430 M°+-2Cl(2),
394 M°+-3Cl (1), 344
M°+-VCl3 (100)
n.d.
n.d.
8.02(t,2H), 7.92(t,2H), 166.5, 166.4, 153.4, 548 M°+(1), 512 M°+-
7.82(d,1H), 7.73(s,1H), 153.4, 141.6, 136.6, Cl (2), 496 M°+-Cl-
7.53(d,1H), 7.49-
7.43(dd,2H), 7.41-
7.35(dd,2H),
136.5, 133.5, 132.1, CH3 (5), 441 M°+-3Cl
132.0, 131.6, 130.8, (3),
127.1, 127.2, 126.3, 405 M°+-4Cl (2),
126.2, 123.8, 123.7, 358M°+-TiCl4 (100),
122.9, 122.8, 21.5
16
17
2.47(s,3H,CH3)-
8.00(t,2H), 7.92(t,2H), 166.5, 166.4, 153.4, 593M°+(3), 558M°+-
7.81(d,1H), 7.72(s,1H), 153.4, 141.6, 136.6, Cl(2), 522 M°+-2Cl(5),
7.53(d,1H), 7.46(d,2H), 136.5, 133.4, 132.1, 485 M°+-3Cl(2),

23
1H NMR
13C NMR
Mass
m/z[%]
Compound No.
δ [ppm]
7.38(d,2H),
2.44(s,3H,CH3)
δ [ppm]
132.0, 131.6, 130.8, 471M°+-3Cl-CH3(2),
127.2, 127.1, 126.3, 450 M°+-4Cl(5), 358
126.2, 123.8, 123.7, M°+-ZrCl4(100),
122.9, 122.8, 21.5
515M°+(2), 478M°+-
Cl(1), 464M°+-Cl-
CH3(3), 443 M°+-
2Cl(3), 407 M°+-
3Cl(3),
n.d.
n.d.
18
19
392M°+-3Cl-CH3(2),
M°+-358 M°+-
VCl3(100),
8.37(d,2H), 8.10(t,2H), 148.2, 134.0, 133.8, 500 M°+(1), 463 M°+-
7.92-7.84(m,4H), 7.64- 133.6, 126.5, 125.1, Cl (2), 428 M°+-2Cl
7.63(m,4H)
115.4
(3), 394 M°+-3Cl (5),
357 M°+-4Cl (2), 310
M°+-TiCl4 (100)
8.27-8.25(dd,2H),
7.94(t,2H), 7.71-
7.67(m,4H), 7.45-
7.42(m,4H)
149.1, 135.0, 132.5, 543 M°+(1), 506 M°+-
126.2, 125.4, 115.3, Cl (1), 437 M°+-3Cl
20
21
22
23
24
114.8
(3), 400 M°+-4Cl (5),
310 M°+-ZrCl4 (100)
467 M°+(1), 430 M°+-
Cl (5), 393 M°+-3Cl
(2), 310 M°+-VCl3
(100)
n.d.
n.d.
8.18-8.16(dd,2H), 7.92- 147.7, 137.6, 133.2, 530 M°+(2), 492 M°+-
7.90(dd,2H), 7.54(d,2H), 131.9, 129.6, 128.9, Cl (10), 454 M°+-2Cl
7.44(s,2H), 7.24(d,2H), 127.6, 126.1, 114.8, (5), 418 M°+-3Cl (2),
2.40(s,6H,2CH3)
114.5, 21.8
338 M°+-TiCl4 (50)
8.27(t,2H), 8.03(d,2H), 147.2, 136.2, 133.8, 571 M°+(1), 498 M°+-
7.64(d,2H), 7.54(s,2H), 133.547, 133.3, 131.8, 2Cl (1), 464 M°+-3Cl
7.35(d,2H),
2.49(s,6H,2CH3)
127.8, 124.7, 114.7, (1), 429 M°+-4Cl (1),
114.43, 21.9
338 M°+-ZrCl4 (100)
495 M°+(2), 425 M°+-
2Cl (1), 388 M°+-3Cl
(1), 338 M°+-VCl3
(100)
n.d.
n.d.
8.22(d,2H), 7.92(t,2H), 151.0, 136.6, 134.5, 568 M°+(1), 481 M°+-
7.74(s,2H), 7.69(d,2H), 132.4, 132.1, 129.3, 2Cl-NH (2), 462 M°+-
7.43(d,2H)
126.6, 125.3, 116.8, 3Cl (10), 426 M°+-4Cl
25
115.1
(2), 378 M°+-TiCl4
(100)
611 M°+(2), 541 M°+-
2Cl (3), 503 M°+-3Cl
8.08(d,2H), 7.76(t,2H), 151.7, 137.7,
7.67(s,2H), 7.61(d,2H), 135.4,131.9, 128.7,
7.25(d,2H)
26
27
127.7, 124.6, 123.4, (2), 467M°+-4Cl (5),
116.8, 115.3
378 M°+-ZrCl4 (100)
535 M°+(1), 464 M°+-
2Cl (2), 428 M°+-3Cl
n.d.
n.d.

24
1H NMR
13C NMR
Mass
m/z[%]
(5), 378 M°+-VCl3
(100)
Compound No.
δ [ppm]
δ [ppm]
8.13(d,1H), 7.70-
7.67(m,4H), 7.45-
7.44(m,6H),
149.2, 143.1, 135.1, 516 M°+ (2), 443 M°+-
134.5, 133.1, 132.7, 2Cl (2), 409 M°+-3Cl
126.0, 125.5, 125.3, (2), 372 M°+-4Cl (2),
122.9, 115.3, 115.2, 324 M°+-TiCl4 (40)
21.6
28
2.51(s,3H,CH3)
8.13(d,1H), 7.69-
7.63(m,4H), 7.42-
7.39(dd,4H), 7.38(s,1H), 126.973, 125.087,
7.37(d,1H),
2,51(s,3H,CH3)
149.8, 142.5, 135.9, 557 M°+(1)
135.1, 132.5, 132.2, 542 M°+-CH3 (5), 414
M°+-4Cl (20), 324 M°+-
124.8, 123.6, 115.4, ZrCl4 (100)
115.2, 21.6
29
30
481 M°+(2) 466 M°+-
CH3 (5), 445 M°+-Cl
(3), 374 M°+-3Cl (3),
324 M°+-VCl3 (100)
n.d.
n.d.
8.27(d,2H), 7.92(d,1H), 147.0, 146.9, 144.3, 542 M°+ (2), 468 M°+-
7.74(d,2H), 7.63(s,2H), 136.6, 136.5, 134.7, 2Cl (2), 433 M°+-3Cl
7.45(d,2H),
2.65(s,6H,2CH3),
2.61(s,3H,CH3)
134.097, 133.6, 133.5, (3), 371 M°+-4Cl -
131.6, 131.4, 129.851, 2CH3 (3), 352 M°+-
129.2, 128.1, 126.3, TiCl4 (100)
124.2, 121.5, 114.8,
31
114.7, 114.5, 22.1,
21.9
8.16(d,2H), 7.82(d,1H), 147.6, 147.2 143.5,
7.63(d,2H), 7.53(s,2H), 135.8, 134.2, 133.7, 2Cl (3), 478 M°+-3Cl
585 M°+ (2), 514 M°+-
7.34(d,2H),
2.47(s,6H,2CH3),
2.30(s,3H,CH3)
133.4, 133.2, 132.2, (5), 413 M°+-4Cl -
131.8, 129.6, 128.9, 2CH3 (3), 352 M°+-
127.5, 126.0, 124.9, ZrCl4 (100)
122.0, 114.7, 114.6,
32
33
114.4, 114.3, 21.9,
21.6
511 M°+ (10), 439 M°+-
2Cl (3), 403 M°+-3Cl
n.d.
n.d.
(5), 373 M°+-3Cl -
2CH3 (3), 352 M°+-
VCl3 (70)
8.06(s,1H), 8.04 (s,2H) 151.2, 142.7, 137.0, 582 M°+(2), 565 M°+-
7.70-7.61(m,4H), 7.39- 136.3, 134.8, 134.1, CH3 (5), 545 M°+-Cl
7.34(m,2H),
2.45(s,3H,CH3)
132.7, 132.5, 132.1, (2), 508 M°+-2Cl (2),
132.1, 126.8, 125.9, 472 M°+-3Cl (5), 458
125.3, 125.1, 123.5, M°+-4Cl-CH3 (5),
116.7, 116.6, 115.2, 393 M°+-TiCl4 (100)
115.0, 21.5
34
35
8.10(s,1H), 8.07 (s,2H), 151.6, 142.4, 137.6, 626 M°+(2), 611 M°+-
7.75-7.64(m,4H), 7.42- 136.9, 135.4, 134.7, CH3 (5), 590 M°+-Cl
7.37(m,2H),
2.51(s,3H,CH3)
132.4, 132.0, 131.5, (2), 553 M°+-2Cl (2),
128.9, 128.7, 127.3, 517 M°+-3Cl (3), 469

25
1H NMR
13C NMR
Mass
m/z[%]
Compound No.
δ [ppm]
δ [ppm]
127.1, 124.9, 124.8, M°+-4Cl-CH3 (5),
116.8, 116.7, 115.3, 393 M°+-ZrCl4 (100)
115.1, 21.6
550 M°+(3), 535 M°+-
CH3 (3), 514 M°+-Cl
(2), 478 M°+-2Cl (5),
428 M°+-3Cl-CH3 (5),
393 M°+-VCl3 (100)
36
n.d.
n.d.
8.12-8.09(dd,2H), 7.83- 162.2, 151.0, 141.9, 502 M°+(1),
7.81(dd,2H), 7.74(t,2H), 132.5, 131.7, 127.4, 466M°+-Cl(2), 429 M°+
37
38
7.54(t,2H), 7.35-
7.33(m,4H)
126.5, 125.5, 120.7, -2Cl(3), 312 M°+ -
111.5
TiCl4 (100),
8.11-8.09(dd,2H), 7.83- 162.2, 151.0, 141.9, 545 M°+(1),
7.81(dd,2H), 7.68(t,2H), 132.5, 131.7, 127.4, 509M°+-Cl(2), 472 M°+
7.53(t,2H), 7.35-
7.33(m,4H)
126.5, 125.5, 120.7, -2Cl(5), 312 M°+ -
111.5
n.d.
ZrCl4 (100),
469 M°+(3),
433M°+-Cl(1), 398 M°+
-2Cl(5),
n.d.
39
40
361M°+-3Cl(2)
312M°+-VCl3(100),
8.12(d,2H), 7.85(t,2H), 162.3, 149.3, 142.2, 530 M°+(1),
7.53(s,2H), 7.46(d,2H), 134.9, 132.4, 131.6, 464 M°+-Cl-2CH3(2),
7.21(d,2H),
2.42(s,6H,2CH3)
127.5, 127.4, 120.5, 459M°+-2Cl(5), 423
110.9, 21.6
M°+ -3Cl(3), 388 M°+-
4Cl (1), 340M°+-
TiCl4(100)
8.23-8.21(dd,2H),
162.6, 149.6, 142.4, 573 M°+(1),
7.97(t,2H), 7.63(s,2H), 135.2, 132.7, 131.9, 506 M°+-Cl-2CH3(1),
7.57(d,2H), 7.31(d,2H), 127.8, 127.7, 120.8, 501M°+-2Cl(3), 465
41
42
2.52(s,6H,2CH3)
111.2, 21.9
M°+ -3Cl(3), 431 M°+-
4Cl (2), 340M°+-
ZrCl4(100)
497 M°+(3),
432M°+-Cl-2CH3(2),
426 M°+ -2Cl(5),
390M°+-3Cl(2)
n.d.
n.d.
340M°+-VCl3(100),
8.14-8.11(dd,2H), 7.87- 161.8, 151.4, 139.8, 530 M°+(3),
7.84(dd,2H), 7.62(d,2H), 136.6, 132.4, 131.7, 494 M°+-Cl(2),
7.41(s,2H), 7.22(d,2H), 127.5, 126.7, 120.2, 430M°+-2Cl-2CH3(5),
43
44
2.43(s,6H,2CH3)
111.5, 21.9
423 M°+ -3Cl(1), 389
M°+-4Cl (2), 340M°+-
TiCl4(100)
8.13-8.10(dd,2H), 7.86- 161.8, 151.4, 139.8, 573 M°+(3),
7.83(dd,2H), 7.61(d,2H), 136.5, 132.4, 131.7, 537 M°+-Cl(2),
7.40(s,2H), 7.21(d,2H), 127.5, 126.7, 120.2, 472M°+-2Cl-2CH3(3),
2.42(s,6H,2CH3)
111.5, 21.9
467 M°+ -3Cl(2), 431

26
1H NMR
13C NMR
Mass
m/z[%]
Compound No.
δ [ppm]
δ [ppm]
M°+-4Cl (2), 340M°+-
ZrCl4(100)
497 M°+(2),
432M°+-Cl-2CH3(2),
426 M°+ -2Cl(3),
390M°+-3Cl(5)
n.d.
n.d.
45
340M°+-VCl3(100),
7.98(d,1H), 7.91(s,1H), 162.3, 162.2, 151.0, 516 M°+,
7.68-7.64(m,2H),
7.61(d,1H), 7.53-
150.9, 142.8, 141.9, 480 M°+-Cl(3),
141.8, 133.0, 132.1, 444M°+-2Cl(2), 408
7.49(dd,2H), 7.32(t,4H), 131.6, 127.3, 126.4, M°+ -2Cl(1), 372 M°+-
46
2,45(s,3H,CH3)
126.3, 125.5, 125.4, 4Cl (2), 326M°+-
124.6, 120.7, 120.6, TiCl4(100)
111.5, 111.4, 21.5
8.00(d,1H), 7.92(s,1H), 162.3, 162.2, 151.0, 560 M°+(1),
7.69-7.65(m,2H),
7.62(d,1H), 7.54-
150.9, 142.8, 141.9, 524 M°+-Cl(2),
141.8, 133.0, 132.2, 474M°+-2Cl-CH3(3),
7.50(m,2H), 7.34(t,4H), 131.5, 127.3, 126.4, 452 M°+ -3Cl(2), 417
47
48
2.45(s,3H,CH3)
126.3, 125.5, 125.4, M°+-4Cl (2), 326M°+-
124.7, 120.7, 120.6, ZrCl4(100)
111.5, 111.4, 21.5
483 M°+(5),
444M°+-Cl(5), 407 M°+
n.d.
n.d.
-2Cl(1), 357 M°+-3Cl
(5), 326(100)
a) Solvent = CDCl3
n.d. not determined
3.2 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 (see Table 4).
3.3 Gel permeation chromatography (GPC)
GPC measurements were routinely performed by SABIC Company (Riyadh, Saudi
Arabia).
3.4 Elemental analysis

27
Elemental analyses (see Table 5) were performed with a VarioEl III CHN instrument.
Therefore, an amount of 4-6 mg of the complex was weighed into a standard tin pan.
The tin pan was carefully closed and introduced into the auto sampler of the
instrument. The raw values of the carbon, hydrogen, and nitrogen contents were
multiplied with calibration factors (calibration compound: acetamide).
3.5 General procedures for the syntheses of the complexes
3.5.1. Syntheses of the organic compounds 1-12
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 in 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 spectrometry (Table 4) and representative examples were
characterized by elemental analysis (Table 5).
3.5.2 Titanium complexes
To 0.87g, (2.6 mmol) TiCl4(THF)2 in dichloromethane was added 2.6 mmol of the free
ligand. The reaction mixture was stirred over night at room temperature, filtered and washed
several times with the reaction solvent pentane and dried under vacuum and weighed. The
products were characterized by NMR and mass spectroscopy (Table 4) and representative
examples were characterized by elemental analysis (Table 5).
3.5.3 Zirconium complexes

28
To 0.45g (1.2mmol) ZrCl4(THF)2 in dichloromethane an amount of 1.2 mmol of the free
ligand was added. The reaction mixture was stirred over night at room temperature, filtered
and washed several times with dichloromethane, then with pentane, dried under vacuum and
weighed. The products were characterized by NMR and mass spectroscopy (Table 4) and
representative examples were characterized by elemental analysis (Table 5).
3.5.4 Vanadium complexes
To 0.41g (2.6 mmol) VCl3 in ether an amount of 2.6 mmol of the free ligand was added. The
reaction mixture was stirred over night at room temperature, filtered and washed several
times with ether and pentane, dried under vacuum and weighed. The products were
characterized by mass spectroscopy and representative examples were characterized by
elemental analysis (Table 5).
Table 5. Elemental analysis data for representative organic compounds and complexes.
1-4, 9, 11, 14, 15, 23, 24, 28, 33, 39, 45, 47.
Calculated
H
Found
H
Compound
No.
1
C
N
C
N
69.77
70.39
77.42
78.11
76.92
77.65
41.59
47.90
46.23
53.33
42.25
49.51
4.52
3.91
4.52
5.33
3.85
4.71
2.08
2.40
3.15
3.64
2.76
3.93
8.14
7.82
18.06
16.57
8.97
8.23
4.58
5.59
9.81
11.31
9.86
11.00
69.74
69.81
77.38
78.62
77.14
77.71
41.97
48.11
47.06
54.12
42.02
48.75
3.52
4.14
4.49
5.17
3.66
4.73
2.01
2.35
3.23
3.71
2.87
3.92
8.11
7.53
18.13
17.12
8.78
8.41
4.66
5.28
8.97
10.96
9.76
10.97
2
3
4
9
11
14
15
23
24
28
33

29
51.17
53.12
45.08
2.56
3.22
2.50
6.00
5.63
5.01
51.06
52.80
44.62
2.55
3.21
2.44
5.87
5.46
4.79
39
45
47
3.6 Polymerization of ethylene in a 1l 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 color change.
The mixture was added to a 1l Schlenk flask filled with 250 ml n-pentane. This
mixture was transferred to a 1l 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.
Conclusions
Organic compounds with hetero atoms are able to coordinate to transition metal halides like
TiCl4, ZrCl4 and VCl3. Such adducts can be activated with a cocatalyst, such as
methylalumoxane (MAO), and then catalyze homogeneous ethylene polymerization. Studies
of structure property relationships show a big dependence of the catalyst performance from
the nature of the hetero atom, the metal and the reaction conditions. The bimodal and
multimodal behavior of some produced polyethylene resins indicate the existence of more
than one active site in these homogeneous catalysts.
Acknowledgements
We thank SABIC company (Riyadh, Saudi Arabia) for GPC measurements and University of
Juba (Khartoum, Sudan) for the financial support of H.A.E. for the first year.