The influence of the ligand structure on the properties of (α-diimine)nickel catalysts in the polymerization and oligomerization of ethylene

Article abstract of DOI:10.1016/S0020-1693(03)00084-7

(α-Diimine)nickel(II) dihalide complexes are suitable catalyst precursors for the polymerization and oligomerization of olefins after activation with methylaluminoxane (MAO). The catalytic properties of these complexes and the character of the obtained po

Full text of DOI:10.1016/S0020-1693(03)00084-7

Inorganica Chimica Acta 351 (2003) 34Á42
/
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The influence of the ligand structure on the properties of
(a-diimine)nickel catalysts in the polymerization and oligomerization
of ethylene
Markus Helldorfer, Judith Backhaus, Helmut G. Alt *
¨
Laboratorium fur Anorganische Chemie, Universitat Bayreuth, Universitatsstraße 30, D-95440 Bayreuth, Germany
¨ ¨ ¨
Received 14 October 2002; accepted 30 December 2002
Abstract
(a-Diimine)nickel(II) dihalide complexes are suitable catalyst precursors for the polymerization and oligomerization of olefins
after activation with methylaluminoxane (MAO). The catalytic properties of these complexes and the character of the obtained
polymers depend on the ligand structure of the used catalysts. Substituents on the arene moiety and/or the backbone of the ligand
influence the active site of the catalyst during the polymerization reaction. Therefore, polymerization products of low molecular
weights (oligomers) to high molecular weights (polymers) can be obtained. Activities, molecular weights of the products and the
formation of various isomers of the obtained oligomers show clear dependencies on the molecular structure of the catalyst
precursors.
# 2003 Elsevier Science B.V. All rights reserved.
Keywords: (a-Diimine)nickel complexes; Ethylene; Oligomer; Polymerization; Catalysis
1. Introduction
ethylene. The catalytic behavior of the complexes and
the relationships between the positions of different
halogen substituents at the arene moieties of the ligand
and different substituents at the ligand backbone were
investigated.
Nickel catalysts have been used for the production of
short chain olefins in the so-called Shell Higher Olefin
Process (SHOP) for 30 years [1Á5]. Since then various
/
types of nickel complexes were discovered as suitable
catalysts for the oligomerization and polymerization of
olefins [6Á
/
15]. (a-Diimine)nickel dihalide complexes
2. Results and discussion
were first described by tom Dieck and Svoboda [16Á
/
19] and are known as polymerization catalysts in
combination with methylaluminoxane (MAO) after
Brookhart and coworkers had investigated their cataly-
2.1. Synthesis of the catalyst precursors
tic potential [20Á29] (Fig. 1).
/
2.1.1. Synthesis of the a-diimine ligands
Other research groups have reported identical or
closely related catalyst systems that can be used for
The synthesis of the a-diimine ligands proceeds via a
condensation reaction of 2 equiv. of a substituted aniline
derivative with 1 equiv. of a 1,2-diketone compound
according to Scheme 1.
In the reactions with 2,3-pentanedione, dichloro-
methane was used as solvent. For the synthesis of the
other ligands, toluene was used. The aniline derivatives
were applied in small excess. The end of the reaction was
indicated by GC spectra of various samples. All ligands
are listed in Fig. 2.
the polymerization of olefins as well [30Á35].
/
Here, we report about the influence of the ligand
structure on the catalytic properties of (a-diimine)nickel
catalysts in the polymerization and oligomerization of
* Corresponding author. Fax: ꢀ
/
49-921-552 157.
E-mail address: helmut.alt@uni-bayreuth.de (H.G. Alt).
0020-1693/03/$ - see front matter # 2003 Elsevier Science B.V. All rights reserved.
doi:10.1016/S0020-1693(03)00084-7

M. Helldorfer et al. / Inorganica Chimica Acta 351 (2003) 34Á
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35
¨
Fig. 1. (a-Diimine)nickel(II) dibromide catalyst precursors.
Fig. 2. Synthesized a-diimine ligands.
Scheme 1. Synthesis of the a-diimine ligands.
2.2. Polymerization of ethylene with the (a-
diimine)nickel(II) complexes 4aÁ6g
/
The (a-diimine)nickel dibromide complexes synthe-
sized above were tested for homogeneous ethylene
polymerization. After activation with MAO (30 wt.%
in toluene), the toluene was removed in vacuo and the
dried catalysts were suspended in pentane and used for a
slurry polymerization reaction. The results are summar-
ized in Table 1.
After the ethylene saturation of the pentane solution
the ethylene flow was almost constant. Only a small
decrease of the ethylene flow during the polymerization
was observed. The tested catalysts produced mixtures of
oligomers and polymers. In order to separate the
oligomers and polymers, the polymerization mixture
was filtered and the remaining polymer was washed with
half concentrated hydrochloric acid and water. The
polymer was dried in vacuo and weighed. The solution
of the oligomers was destilled over a Vigreux column in
order to remove pentane. The obtained oligomers were
analyzed by GC. The classification for oligomers and
polymers was the solubility of the products in pentane.
Mass spectrometric analyses suggested a molecular
weight of approximately 1000 g molꢁ1 as the border
line. Based on the GC analyses of the oligomer mixtures,
1
Compounds 1aÁ
/
3g were characterized by H and 13C
NMR spectroscopy. The corresponding data are sum-
marized in Table 2.
2.1.2. Synthesis of the(a-diimine)nickel(II) complexes
The synthesis of the (a-diimine)nickel(II) complexes
follows a ligand displacement reaction [16,17]. There-
fore, the corresponding a-diimine ligand is dissolved in
tetrahydrofuran and reacted with an equimolar amount
of dimethoxyethane nickel dibromide [36]. The synthe-
sized complexes are summarized in Scheme 2.
Complexes 4aÁ6g were identified by mass spectro-
/
metry. The characterization of these compounds by
NMR spectroscopy is not very informative due to the
paramagnetism of the complexes. The mass spectro-
metric analyses revealed the molecule ion only in the
case of the complexes 4a and 4c. For the other
complexes, only fragments deriving from the loss of
one or two halogen atoms were observed. All mass
spectrometric data of complexes 4aÁ
Table 3.
/
6g are given in

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M. Helldorfer et al. / Inorganica Chimica Acta 351 (2003) 34Á42
/
¨
it is possible to calculate the SchulzÁ/Flory-constant a
[37Á40] for the distribution of the oligomer fractions.
/
For this calculation, the area integrals of the oligomer
fractions with carbon atom numbers from 10 to 30 were
used. Due to the formation of both isomers of the
olefins and polymers, the values of a imply a statistical
error especially in the case of 5a were a ꢀ/1. All values of
a are included in Table 1.
A comparison of the observed activities supports the
theory that the activity of an (a-diimine)nickel(II)
catalyst is a function of the steric demands, the
electronegativity and the position of the substituents at
the aryl moieties of the ligand (Fig. 3).
Similar results have been found earlier [21,24,41,42].
Therefore, the catalysts 4d/MAO, 5c/MAO and 6g/
MAO with bulky iodine substituents show good activ-
ities especially when the iodine substituent is located in
the ortho-position of the aryl moiety.
The influence of the substituents at the ligand back-
bone can be shown by comparing catalysts with
different groups at the backbone and the same substitu-
tion pattern at the aryl moiety like 4a/MAO, 5a/MAO
and 6e/MAO with a fluorine substituent in para-
position, 4b/MAO, 5b/MAO and 6b/MAO with a
chlorine substituent in para-position and 5c/MAO and
6g/MAO with a iodine substituent in ortho-position. In
these cases, the tendency can be observed that the
activity increases if the substituents at the ligand back-
bone are changed from a methyl and an ethyl group (4a/
MAO, 4b/MAO), to two ethyl groups (5a/MAO, 5b/
MAO, 5c/MAO) and the activity decreases if there are
Scheme 2. Synthesis of the (a-diimine)nickel dibromide complexes 4aÁ
/
6g.
Table 1
Results of the homogeneous ethylene polymerization for the (a-diimine)nickel(II) complexes 4aÁ
6g activated with MAO a
/
b
d
f
No.
Activity
TOF c
Polymer share [wt.%]
a
1-Octene e
Mw (polymer share) [g molꢁ1
]
D
4a
4b
4c
4d
5a
5b
5c
6a
6b
6c
6d
6e
6f
1032
998
38 700
37 425
36 750
71 325
56 550
44 475
154 050
21 113
33 675
11 663
26 175
57 225
9900
B
/
1
1
1
1
0.69
0.68
0.70
0.75
0.98
n.d.
n.d.
n.d.
0.53
0.53
0.65
0.66
n.d.
n.d.
35.3
40.7
39.9
56.7
45.3
n.d.
n.d.
n.d.
n.d.
n.d.
n.d.
n.d.
7.1
B
/
980
B
/
n.d.
n.d.
1902
1508
1186
4108
563
B
/
33
50
3850
4780
6380
4010
1100
n.d.
5.8
7.2
100
70
2.2
898
311
10
25
45.5
50.8
58.5
61.4
13.2
n.d.
n.d.
10.5
n.d.
15.9
698
22.7
12.5
100
100
n.d.
1526
264
4410
n.d.
6g
1232
46 200
4340
n.d., not determined.
a
Polymerization conditions: activation with 30 wt.% MAO in toluene (Al/Niꢂ
/1000/1; polymerization in 250 ml pentane, 60 8C, 1 l autoclave, 10
bar ethylene pressure, 60 min).
b
The activities [g(prod.) (mmol(Ni) h)ꢁ1] were calculated from the total consumption of ethylene (1.0 l ethyleneꢂ
TOF [mol(C2H4) (mol(Kat.) h)ꢁ1]ꢂ
turn over frequency.
rate of propagation/(rate of propagationꢀ
1-Octene share [mol%] of all octene isomers.
D, polydispersity Mw/Mn of the polymer share.
/1.2 g product).
c
d
e
f
/
aꢂ
/
kB/(kBꢀ
/
kC)ꢂ
/
/
rate of chain transfer)ꢂ
/
SchulzÁFlory-constant.
/

M. Helldorfer et al. / Inorganica Chimica Acta 351 (2003) 34Á
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37
¨
Fig. 3. Comparison of the observed activities of the catalyst precursors 4aÁ6g.
/
two bulkier phenyl groups at the backbone (6b/MAO,
6g/MAO).
Also the composition of the polymerization products
can be related with the structure of the catalyst
precursors (Fig. 4).
The catalysts 4a/MAO and 4b/MAO produce almost
only oligomers. The corresponding catalysts 5a/MAO
and 5b/MAO with two ethyl groups at the ligand
backbone have a clearly higher polymer share in the
product mixture (5a/MAO: 33 wt.%; 5b/MAO: 50
wt.%). For the catalysts 6e/MAO and 6b/MAO with
the same substitution pattern at the aryl moiety and two
phenyl groups at the ligand backbone, the polymer
share decreases although the phenyl groups are more
bulky than the ethyl groups. The catalysts 5c/MAO and
6g/MAO polymerize ethylene only to a polymer due to
the steric demands of the ortho-iodine substituents. In
that cases syn and anti isomers of the catalysts are
possible and, therefore, different steric hinderance of the
catalytic center determine the nature of the products.
This seems to have no influence on the polymerization
products, because the GPC analysis does not reveal any
bimodal mass distribution. The comparatively high
values for the polydispersities D can be related to an
Fig. 4. Composition of the products obtained with the catalyst precursors 4a, 4b, 5a, 5b, 5c, 6b, 6e, 6g.

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increasing interaction between the substituents at the
ligand backbone and the aryl groups, especially in the
case of bulky phenyl groups at the ligand backbone.
Another indication for the influence of the ligand
structure on the polymerization behavior of the (a-
diimine)nickel catalysts is the selectivity to produce 1-
octene from ethylene. Polymerization reactions with (a-
diimine)nickel(II) catalysts that produce oligomers nor-
mally lead to a mixture of double bond isomers of each
olefin fraction. This can be explained with the so-called
An increasing steric demand of the substituents at the
ligand backbone obviously leads to a higher selectivity
to give 1-octene.
The molecular weights of the polymerization pro-
ducts, the formation of double bond isomers and also
the activities are mainly influenced by the availability of
the axial coordination sites of the catalytic center [44,45]
(Fig. 6).
Isomerization and chain transfer reactions can only
take place when these coordination sites are not
sterically hindered by substituents at the aryl moieties
of the ligand. On the other hand, the orientation of the
aryl ring to the planar diimine-nickel ring is flexible. The
aryl rings can occupy a position between a coplanar and
a perpendicular orientation (Fig. 7).
This flexibility is hindered when the substituents at
the ligand backbone are more bulky. Bulky substituents
at the ligand backbone fix the aryl rings in perpendicular
‘chain running’ mechanism [20Á29,43] (Scheme 3).
/
The main influence on the selectivity to a-olefins is
caused by the substituents on the aryl moieties of the
ligand and the ethylene pressure during the polymeriza-
tion. A comparison of the catalysts 4a/MAO, 5a/MAO
and 6e/MAO shows that also the ligand backbone plays
a certain role as the composition of the octene fraction
indicates (Fig. 5).
Scheme 3. Chain running mechanism [20Á29,43].
/

M. Helldorfer et al. / Inorganica Chimica Acta 351 (2003) 34Á
/42
39
¨
Fig. 5. Selectivity for the formation of 1-octene in the case of 4a, 5a and 6e.
catalysts provide products with a low molecular weight.
The reason for this behavior is not related to more chain
transfer reactions by using the axial positions but to a
smaller space for the growing polymer chain at the
catalytic center that leads to b-hydrogen elimination and
thus to shorter polymer chains.
The catalysts with two ethyl groups at the ligand
backbone show still a certain flexibility of the ligand
framework. In that case, the activities are comparatively
high because chain transfer reactions and the isomeriza-
tion are suppressed and the coordination and insertion
of the monomer is the dominating step. If one sub-
stituent at the ligand backbone is a methyl group, at
least one of the aryl rings shows no steric hinderance.
Therefore, short chain oligomers, a high isomerization
rate and lower activities are the result. The kinetics of
the polymerization reactions catalyzed by (a-diimi-
ne)nickel complexes depend very much on various
parameters influenced by the structural situation in the
used catalysts. Only small changes in the ligand struc-
ture can lead to significant differences of the catalytic
properties.
Fig. 6. Axial (Ax) and equatorial (Eq) coordination sites of the metal
center and their steric interactions with the ortho-substituents [44,45].
Fig. 7. Possible orientations of the aryl rings to the diimine-nickel ring
in a (a-diimine)nickel(II) catalyst [44,45].
positions. In that case the interaction of the aryl rings
with the axial coordination sites of the nickel center is a
maximum. Therefore, the catalysts with two phenyl
groups at the ligand backbone show comparatively low
activities because the coordination of the ethylene
monomer via these axial coordination sites is hindered.
Also the isomerization of the double bond of the
obtained olefins is suppressed. On the other side, these
3. Experimental
NMR spectroscopic investigations were performed
with a Bruker ARX 250 instrument. All organometallic
samples were prepared under Ar and measured at 25 8C.
CDCl3 served as solvent. The chemical shifts (d) in the
1H NMR spectra are referenced to the residual proton
signal of the solvent (dꢂ7.24 ppm for CHCl3) and in
/

40
M. Helldorfer et al. / Inorganica Chimica Acta 351 (2003) 34Á
/42
¨
13C NMR spectra to the solvent signal (dꢂ
CHCl3-d1).
/77.0 ppm for
mixture using a Dean-Stark apparatus. The progress of
the reaction was observed by GC. After 12Á24 h the
/
MS spectra were recorded with a VARIAN MAT
CH7 mass spectrometer (direct inlet system, electron
impact ionization 70 eV). In addition, a Hewlett-
Packard 5917A mass spectrometer was routinely used
to record MS spectra and in combination with a
Hewlett-Packard Series II 5890 gas chromatograph to
record GC/MS spectra.
Molecular weight determinations of the polyethylene
samples were performed using a Millipore Waters 150 C
HT-GPC with refractometric detection (RI Waters 401).
The polymer samples were dissolved in 1,2,4-trichlor-
obenzene (flow rate 1 ml minꢁ1) and measured at
150 8C.
reaction mixture was cooled to r.t. and filtered over
silica. After removing the solvent in vacuo, the product
was precipitated with cold MeOH. For purification the
products were recrystallized from a MeOH/EtOH mix-
ture (3:1). The ligands were obtained as yellow crystals.
Yields: 2a: 60%, 2b: 75%, 2c: 75%, 3a: 35%, 3b: 40%,
3c: 55%, 3d: 35%, 3e: 25%, 3f: 35%; 3g: 25%.
All compounds were characterized by NMR spectro-
scopy (Table 2).
3.3. General procedure for the synthesis of the (a-
diimin)nickel dibromide complexes 4aÁ6g
/
Gas chromatograms were recorded using a PerkinÁ
/
Respective a-diimine ligand (5 mmol) was dissolved in
150 ml THF. Then 5 mmol of dimethoxyethane nickel
dibromide were added under Ar atmosphere. The
mixture was stirred for 8 h at r.t. For purification, the
solvent was reduced in vacuo and the complexes were
precipitated by adding pentane. After washing several
times with pentane until the solvent stayed colorless, the
products were dried in vacuo. The complexes were
obtained as crystalline powders.
Yields: 4a: 95%, 4b: 95%, 4c: 90%, 4d: 95%, 5a: 90%,
5b: 90%, 5c: 90%, 6a: 90%, 6b: 85%, 6c: 85%, 6d: 85%,
6e: 85%, 6f: 90%, 6g: 85%.
The complexes were identified by mass spectrometry
(Table 3).
Elmer Auto System gas chromatograph with flame
ionization detector (FID) and helium as carrier gas (1
ml minꢁ1).
Temperature program:
Starting phase: 3 min at 50 8C
Heating phase: 5 8C minꢁ1 (15 min)
Plateau phase: 310 8C (15 min)
Methylaluminoxane was supplied by Witco GmbH,
Bergkamen, as 30% solution in toluene (average mole-
cular weight 1100 g molꢁ1, aluminum content: 13.1%,
3.5% as trimethylaluminum).
The synthesized complexes did not show a melting
point under inert atmosphere but decomposition at
higher temperatures.
3.1. General synthesis procedure for the a-diimine ligands
1aÁ1d
/
Decomposition temperatures: 4a: 250 8C, 4b: 250 8C,
4c: 230 8C, 4d: 220 8C, 5a: 240 8C, 5b: 250 8C, 5c: 210 8C,
6a: 220 8C, 6b: 220 8C, 6c: 210 8C, 6d: 210 8C, 6e: 220 8C,
6f: 200 8C, 6g: 210 8C.
To a solution of 40 mmol of the respective aniline
derivative in CH2Cl2, 15 mmol of the corresponding
diketo compound and a catalytic amount of p-toluene
sulfonic acid were added. The mixture was heated under
reflux. The progress of the reaction was observed by
The purity of complexes 4b and 5b was tested by
microanalyses: 4b: Cꢂ
3.19% (Hcalc 3.00%); 5b: Cꢂ
Hꢂ3.53% (Hcalc 3.29%).
/
37.35 (Ccalc
ꢂ
/
37.97%), Hꢂ
/
GC. After 12Á
/
24 h the reaction mixture was cooled to
ꢂ
/
/38.00 (Ccalc
ꢂ
/
39.18%),
room temperature (r.t.) and filtered over silica. After
removing the solvent in vacuo, the product was pre-
cipitated with cold MeOH. For purification, the pro-
ducts were recrystallized from a MeOH/EtOH mixture
(3:1). The ligands were obtained as yellow crystals.
Yields: 1a: 85%, 1b: 80%, 1c: 75% 1d: 70%.
/
ꢂ
/
3.4. General procedure for the activation of the (a-
diimine)nickel(II) complexes
Corresponding complex (5Á/10 mg) was suspended in
All compounds were characterized by NMR spectro-
scopy (Table 2).
toluene and activated with an excess of MAO (Al/Niꢂ
/
1000/1). The solvent was removed in vacuo and the
activated catalyst was suspended in 50 ml n-pentane.
The catalyst suspension was used for ethylene polymer-
ization within 30 min.
3.2. General synthesis procedure for the a-diimine ligands
2aÁ3g
/
To a solution of 40 mmol of the respective aniline
derivative in toluene, 15 mmol of the corresponding
diketo compound and a catalytic amount of p-toluene-
sulfonic acid were given. The mixture was heated under
reflux. The resulting water was removed as azeotropic
3.5. Homogeneous ethylene polymerization
The activated complex was added to a 1 l metal
autoclave (Buchi), filled with 250 ml n-pentane. The
¨
polymerizations were performed under an ethylene

M. Helldorfer et al. / Inorganica Chimica Acta 351 (2003) 34Á
/42
41
¨
Table 2
NMR data for compounds 1aÁ3g
/
No. 1H NMR a
13C NMR b
3
1a 7.05 (m, 4H), 6.73 (m, 4H), 2.62 (q, 2H, JHH
1
7.5 Hz), 2.11 (s, 3H), Cq : 173.5, 167.6, 159.7 (d, JCF
1
242 Hz), 159.5 (d, JCF
ꢂ
/
ꢂ
ꢂ
/
ꢂ/
242 Hz),
3
1.07 (t, 3H, JHH
ꢂ/
7.5 Hz)
146.7, 146.6; CH: 120.2 (d, 3JCF
/
8 Hz), 119.8 (d, 3JCF
ꢂ/8 Hz), 115.7
2
(d, JCF
ꢂ/22 Hz); CH2: 21.7; CH3: 15.7, 12.9
3
1b 7.31 (m, 4H), 6.70 (m, 4H), 2.61 (q, 2H, JHH
ꢂ
/
7.5 Hz), 2.09 (s, 3H), Cq : 173.2, 167.5, 149.24, 149.16, 129.2, 128.9; CH: 129.10, 129.07,
120.2, 119.8; CH2: 21.8; CH3: 15.8, 13.0
7.5 Hz), 2.08 (s, 3H), Cq : 173.1, 167.4, 149.64, 149.61, 116.9, 116.6; CH: 132.03, 132.00,
3
1.06 (t, 3H, JHH
ꢂ
/
7.5 Hz)
1c 7.46 (m, 4H), 6.64 (m, 4H), 2.59 (q, 2H, JHH
3
ꢂ
/
3
1.05 (t, 3H, JHH
ꢂ/
7.5 Hz)
1d 7.64 (m, 4H), 6.53 (m, 4H), 2.59 (q, 2H, JHH
120.5, 120.2; CH2: 21.8; CH3: 15.8, 12.9
7.5 Hz), 2.08 (s, 3H), Cq : 172.9, 167.3, 150.2, 87.5, 87.1; CH: 137.91, 137.86, 120.8, 120.5;
3
ꢂ
/
3
1.05 (t, 3H, JHH
2a 7.00 (m, 2H), 6.67 (m, 2H), 2.55 (q, 4H, JHH
3JHH
7.5 Hz)
2b 7.27 (m, 4H), 6.64 (m, 4H), 2.53 (q, 4H, JHH
3JHH
7.5 Hz)
2c 7.86 (dd, 2H, JHH
4JHH
1.25 Hz), 6.81 (dt, 2H, JHH
ꢂ/
7.5 Hz)
CH2: 21.8; CH3: 15.8, 12.9
7.5 Hz), 0.99 (t, 6H, Cq : 172.2, 160.0 (d, 1JCF
3
ꢂ/
ꢂ/
242 Hz), 146.3; CH: 119.7 (d, 3JCF
ꢂ/8 Hz),
2
115.7 (d, JCF
ꢂ/
ꢂ/22 Hz); CH2: 21.8; CH3: 12.5
3
ꢂ/7.5 Hz), 0.99 (t, 6H, Cq : 172.1, 149.2, 128.7; CH: 129.1, 119.8; CH2: 21.9; CH3: 12.5
ꢂ/
3
4
3
ꢂ
/
8.0, JHH
ꢂ
/
1.3 Hz), 7.33 (dt, 2H, JHH
ꢂ/7.5,
Cq : 172.6, 153.2, 130.2, 88.3; CH: 139.1, 128.8, 125.1, 118.4; CH2: 22.4;
3
4
ꢂ
/
ꢂ
/
7.5, JHH
ꢂ1.5 Hz), 6.74, (dd, CH3: 12.0
/
3
4
3
2H, JHH
3
6H, JHH
ꢂ
ꢂ/
/
7.5, JHH
ꢂ
/
1.3 Hz), 2.68 (q, 4H, JHH
ꢂ/7.3 Hz), 1.14 (t,
2.5 Hz)
3
3a 7.89 (d, 4H, JHH
3
7.5 Hz), 7.40 (m, 12H), 7.13 (t, 2H, JHH
ꢂ
/
ꢂ/
7.5
Cq : 163.9, 149.3, 137.6; CH: 134.3, 131.4, 128.7, 128.3, 124.7, 120.2
3
Hz), 6.53 (d, 2H, JHH
ꢂ/7.5 Hz)
3b 7.86 (m, 4H), 7.45 (m, 6H), 7.04 (m, 4H), 6.44 (m, 4H)
3c 7.87 (m, 4H), 7.44 (m, 10H), 7.02 (m, 2H), 6.39 (m, 2H)
Cq : 164.3, 147.7, 137.2, 130.4; CH: 131.6, 128.9, 128.6, 128.3, 121.5
Cq : 164.3, 150.5, 137.2, 134.1; CH: 131.7, 129.5, 128.9, 128.4, 124.9,
120.6, 117.4
3d 7.98 (m, 2H), 7.45 (m, 2H), 7.22 (m, 2H), 6.94 (m, 10H), 6.64 (m, 2H) Cq : 164.1, 145.7, 137.3, 128.1; CH: 130.0, 129.1, 128.8, 128.5, 126.8,
125.0, 118.7
1
7.31 (m, 6H), 6.71 (m, 4H), 6.45 (m, 4H) Cq : 164.0, 160.3 (d, JCF
3e 7.81 (m, 4H) ꢂ
/
7.5 Hz), 7.43Á
/
ꢂ247 Hz), 145.4, 137.3; CH: 131.4, 128.9,
/
3
128.2, 121.7 (d, JCF
2
8 Hz), 115.2 (d, JCF
ꢂ/
ꢂ/22 Hz)
3f 7.98 (m, 2H), 7.44 (m, 4H), 6.88 (m, 10H), 6.39 (m, 2H)
Cq : 163.6, 146.7, 137.3, 118.8; CH: 132.9, 130.0, 128.7, 128.5, 127.5,
125.3, 118.7
3g 7.99 (m, 4H), 7.71 (m, 2H), 7.44 (m, 6H), 7.00 (t, 2H), 6.72 (m, 2H), Cq : 162.8, 148.8, 137.3, 95.4; CH: 139.2, 131.6, 129.0, 128.9, 128.5,
126.8, 118.1
6.63 (m, 2H)
a
250.13 MHz, 25 8C, in chloroform-d1, d [ppm] rel. chloroform (7.24).
62.9 MHz, 25 8C, in chloroform-d1, d [ppm] rel. chloroform-d1 (77.0).
b
pressure of 10 bar (99.98% ethylene, dried over alumi-
nium oxide) and at a temperature of 60 8C. After a
period of 1 h, the autoclave was cooled to r.t. and the
pressure was reduced. The polymerization mixture was
filtered; the remaining polymer was washed with half
concentrated HCl, dried in vacuo and weighed. After
removing n-pentane by destillation over a Vigreux
column, the obtained oligomers were analyzed by GC.
Table 3
Mass spectrometric data of complexes 4aÁ
/6g
No. Fragment [m/z] (intensity [%])
No. Fragment [m/z] (intensity [%])
4a
4b
4c
4d
5a
5b
5c
M
ꢀ ꢂ
(85)
ꢀ(ꢁ
166 (100), 152 (50), 111 (40), 75 (20)
ꢀ ꢂ
627 (1), 546 (4), 408 (65), 329 (10), 210 (100), 196 (85), 155 6c
(60), 132 (10), 76 (20)
ꢀ(ꢁ
Br)ꢂ641 (3), 594 (3), 502 (40), 454 (25), 375 (10), 258 6d
(100), 244 (70), 210 (40), 76 (70)
/
505 (1), 425 (5), 310 (2), 286 (100), 150 (100), 135 (100), 95 6a
M
M
ꢀ(ꢁ
/
Br)ꢂ
/
499 (1), 419 (8), 360 (60), 281 (10), 180 (100), 77 (25)
M
/
Cl)ꢂ/504 (1), 459 (2), 409 (5), 394 (5), 320 (20), 285 (5), 6b
ꢀ(ꢁ
/
Cl)ꢂ
/
612 (1), 567 (5), 487 (1), 456 (20), 428 (35), 214 (100), 179
(10), 125 (20), 111 (25), 89 (20), 75 (15)
ꢀ(ꢁ
Cl)ꢂ612 (1), 566 (1), 535 (1), 473 (10), 427 (20), 258 (75), 214
(100), 180 (15), 111 (40), 75 (15)
ꢀ(ꢁ
Cl)ꢂ612 (1), 566 (1), 535 (1), 427 (2), 393 (60), 258 (10), 214
(100), 180 (10), 111 (40), 75 (30)
M
/
M
/
/
M
/
/
M
/
/
M
ꢀ(ꢁ
(20)
ꢀ(ꢁ
/Br)ꢂ/438 (1), 300 (15), 267 (5), 150 (100), 136 (18), 95 6e
M
ꢀ(ꢁ
/
Br)ꢂ
/
535 (3), 396 (100), 301 (5), 198 (90), 95 (70), 77 (20)
M
/Br)ꢂ/470 (1), 422 (4), 378 (10), 332 (30), 210 (20), 166 6f
M
ꢀ(ꢁ
/
Br)ꢂ
/
657 (1), 518 (5), 437 (20), 357 (10), 261 (100), 179 (20), 75
(100), 138 (10), 111 (20), 75 (8)
ꢀ(ꢁ
2Br)ꢂ570 (5), 516 (5), 389 (95), 343 (10), 258 (100), 203 6g
(20), 130 (15), 76 (15)
(35)
ꢀ(ꢁ
(90), 77 (20)
M
/
/
M
/Br, ꢁ
/
I)ꢂ624 (3), 612 (3), 485 (35), 359 (70), 306 (100), 180
/

42
M. Helldorfer et al. / Inorganica Chimica Acta 351 (2003) 34Á
/42
¨
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