Synthesis, characterization and catalytic properties of metallacyclic zirconocene complexes

Article abstract of DOI:10.1016/S0022-328X(00)00004-8

A series of 22 metallacyclic zirconocene complexes has been synthesized by the reaction of ω-phenyl-substituted zirconocene dichloride complexes with two equivalents of n-butyllithium via CH bond-activation reactions on the phenyl ring. After activation with methyl aluminoxane, these metallacycles are up to five times more active ethylene polymerization catalysts than the original metallocene dichloride complexes similarly activated.

Full text of DOI:10.1016/S0022-328X(00)00004-8

www.elsevier.nl/locate/jorganchem
Journal of Organometallic Chemistry 599 (2000) 261–274
Synthesis, characterization and catalytic properties of metallacyclic
zirconocene complexes
Erik H. Licht, Helmut G. Alt *, M. Manzurul Karim 1
Laboratorium fu¨r Anorganische Chemie, Lehrstuhl fu¨r Anorganische Chemie II, Uni6ersita¨t Bayreuth, Uni6ersita¨tstrasse 30, NW I,
D-95440 Bayreuth, Germany
Received 29 July 1999; received in revised form 15 December 1999; accepted 15 December 1999
Abstract
A series of 22 metallacyclic zirconocene complexes has been synthesized by the reaction of v-phenyl-substituted zirconocene
dichloride complexes with two equivalents of n-butyllithium via CH bond-activation reactions on the phenyl ring. After activation
with methyl aluminoxane, these metallacycles are up to five times more active ethylene polymerization catalysts than the original
metallocene dichloride complexes similarly activated. © 2000 Elsevier Science S.A. All rights reserved.
Keywords: Metallacycles; Zirconocene complexes; CH activation; Catalysis; Ethylene polymerization
1. Introduction
2. Results and discussion
Metallocene catalysts, used for polymerizing a-
olefins, have been either unbridged or bridged metal-
locene dichloride complexes in combination with
methylaluminoxane (MAO) [1–24]. In the work de-
scribed here, a new class of metallocene complexes,
metallacycles, is described for the polymerization of
a-olefins.
After the activation with MAO, metallacyclic zir-
conocene complexes, containing a substituent directly
linked to the center metal, are well suited for catalytic
olefin polymerization [25,26]. Prior to this work, an
efficient method of synthesizing these metallocycles was
not available [25–30]. Here, we present a general, easy
and efficient synthetic method for the preparation of
metallacyclic zirconocene complexes. These metallacy-
cles were then studied to determine the effects of cy-
clometallation on a-olefin polymerization reactions.
2.1. Synthesis of metallacyclic zirconocene complexes
using CH bond acti6ation reactions
Metallacycles in this paper are defined as metallocene
complexes with a substituent on at least one of the
p-ligands forming a s-bond or a p-bond to the central
transition-metal atom.
The newly developed synthesis method for the forma-
tion of these metallacycles consists of reacting v-pheny-
lalkyl-substituted zirconocene dichloride complexes
with two equivalents of n-butyllithium. The key reac-
tion step for this method is CH bond activation that
leads to cyclometallation. The reaction is presumed to
proceed as shown below.
During this reaction a zirconocene dibutyl complex
[31], which is stable for some minutes in solution at low
temperatures (−40°C), is formed as an intermediate.
The unsubstituted parent compound of this complex
was characterized using spectroscopy [32]. Subse-
quently, the dibutyl complex eliminates n-butane
[33,34] via a b-H transfer reaction. This results in the
* Corresponding author. Tel.: +49-921-552555; fax: +49-921-
552157.
E-mail address: helmut.alt@uni-bayreuth.de (H.G. Alt)
1 Alexander von Humboldt awardee from Jahangirnagar Univer-
sity, Dhaka, Bangladesh.
formation of
a
reactive (h2-butene) complex.
Cp2ZrC4H8, formed as an intermediate during the reac-
tion of Cp2ZrCl2 with two equivalents of n-butyl-
lithium, can be trapped, using trimethylphosphine, and
0022-328X/00/$ - see front matter © 2000 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(00)00004-8

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E.H. Licht et al. / Journal of Organometallic Chemistry 599 (2000) 261–274
characterized [35–37] (see Section 2.4). The v-phenyl-
alkyl group of the (h2-butene) metallocene complex,
shown in Fig. 1, then further reacts to yield the corre-
sponding metallacycle via a CH bond activation
reaction.
A large number of metallocene dichloride complexes
with a variety of p-ligands and substituents were re-
acted with n-butyllithium to study the influence of
steric factors on the course of the cyclometallation
reaction. The metallacycles are numbered 1, 2, etc. and
the respective metallocene dichloride precursors 1c, 2c,
etc.
cular interactions between the phenyl group and the
center metal atom are much more difficult and, as a
result, product mixtures are obtained that have not yet
been identified (Fig. 2).
Similar intramolecular activation reactions of the
aromatic CH-bond are also observed when substituted
benzyl derivatives (4-methyl, 3,5-dimethyl, 4-fluoro and
benzo anellated) are used. Metallacycles are produced
in 80–90% yields when metallocene dichloride com-
plexes with v-phenylalkyl-substituted cyclopentadienyl
ligands carrying one methyl group in position 2 are
reacted with n-butyllithium. Replacement of a C1-
spacer with a Si-spacer leads to very high yields of
metallacycles. The metallacycles and metallocene com-
plexes shown in Fig. 3 were synthesized starting with
the corresponding metallocene dichloride complexes.
The mono-substituted zirconocene dichloride com-
plex 16c reacts with n-butyllithium to give metallacycle
16 (Fig. 4). The CH-activation and cyclometallation
reaction yields are not quantitative in this example due
to low steric shielding of the metal from only one
sterically demanding substituent. Metallacycle 16 is
produced in only 60% yield.
2.2. Synthesis of metallacyclic complexes
Metallocene dichloride complexes containing v-
phenylalkyl-substituted cyclopentadienyl ligands Cp% of
the type (Cp%)2ZrCl2 [38] or (Cp%)(Ind)ZrCl2 [39] are
well suited as starting materials for the synthesis of
metallacyclic complexes. Only a single reaction product
is obtained when the metallocene dichloride complexes
with a C1, C2 or C3 carbon chain between the p-ligand
and the phenyl group (C1-, C2- or C3-spacer) are re-
acted with n-butyllithium. The NMR spectroscopic in-
vestigation (see Section 2.3) confirms that the formed
metallacycles contain a carbon zirconium s-bond (1
and 2). No carbon zirconium s-bond was found for the
metallacycles containing a C3-spacer (3). In the latter
case, the phenyl substituent is fixed at the metal via an
agostic hydrogen atom in the ortho position. Such a
coordination mode has also been observed very recently
by Green and coworkers [40]. If metallocene dichloride
complexes with C4- or C5-spacers are used, intramole-
Metallocene dichloride complexes with v-pheny-
lalkyl-substituted indenyl ligands are also suitable start-
ing compounds for cyclometallation reactions. They
react with two equivalents of n-butyllithium as shown
in the reaction scheme in Fig. 4. The products formed
are metallacycles or metallocene butene complexes (see
Section 2.4 for structural discussions).
The metallacycles and metallocene butene complexes
shown in Fig. 5 were synthesized using this method.
Fig. 1. Proposed reaction scheme for synthesizing a metallacycle from a metallocene dichloride complex.

E.H. Licht et al. / Journal of Organometallic Chemistry 599 (2000) 261–274
263
Fig. 2. Reaction of v-phenylalkyl-substituted zirconocene dichloride complexes with two equivalents of n-butyllithium.
signals (C(1–4) and C(13–16)) for both cyclopentadi-
enyl ligands in the region of l=120–130 ppm are
significant for metallacycle 1 (chiral metallocene com-
plex). Due to this interaction, two different resonance
signals in the region of l=28–40 ppm are found for
the C1-spacer groups (C(6) and C(18)). In a similar
way, a larger number of resonance signals are observed
for the carbon atoms of both phenyl groups (C(7–12)
and C(19–24)) compared with the non-bonded phenyl
groups of the corresponding metallocene dichloride
complexes (three resonance signals). A typical shift to
lower field for the zirconium-bonded quaternary carbon
C(12) of the phenyl group is observed at l=186.0
ppm. The shift differs significantly from carbon-bonded
quaternary phenyl carbon atoms (l=120–150 ppm).
Due to the deshielding of the central metal, the carbon
atom C(7) of the phenyl group is significantly shifted to
lower field at l=166.3 ppm.
2.3. Spectroscopic characterization of the
metallocene complexes
Metallocene complexes 1–22a,b were characterized
1
using H-, 13C- and 29Si-NMR spectroscopy. Spectral
1
results are listed in Table 2. The H- and 13C-NMR
spectra of metallocene complex 1 are discussed below as
an example.
Fig. 6 shows the 1H-NMR spectrum of 1. Eight
different resonance signals at l=6.56, 6.12, 5.98, 5.89,
5.85, 5.68, 5.49 and 5.08 ppm are assigned to the eight
cyclopentadienyl protons. This indicates a chiral metal-
locene complex structure caused by the ZrꢀC s-bond
(ZrꢀC(12)) to the central metal atom. The resonance
signals for the protons of the butyl group are found as
multiplets at l=1.67 (b-CH2) and 1.35 ppm (g-CH2),
3
as a triplet at l=1.02 ppm (CH3; J(1H1H)=7.3 Hz)
and as multiplets at l=0.90 and 0.52 ppm (a-CH2).
The different chemical shifts for both protons of the
methylene group in the a-position and the higher spin
order of its splitting pattern are remarkable and corre-
spond to an a-agostic interaction with the central
metal. The signals for both phenyl groups appear at
l=7.51 ppm (H(11)) and in the region of l=7.25–
6.85 ppm (8H). Due to cyclization, the protons of the
C1-spacer (H(18a,b)) form two doublets at l=4.03 and
3.90 ppm (2J(1H1H)=16.7 Hz), while the protons of
the C1-spacer (H(18)) of the free benzyl substituent
appear as singlet at l=3.53 ppm.
The resonance signal for the methylene group in the
a-position to zirconium of the butyl group (C(25)) is
found at l=58.8 ppm. Due to the direct bond to the
metal, the signal is shifted significantly to lower field
compared with the remaining carbon resonance signals
of the butyl group (C(26–28): l=35.1, 29.7 and 14.1
ppm.
2.4. Discussion of the tendency to form metallacyclic
metallocene complexes
Fig. 7 represents the 13C-NMR spectrum of metalla-
cycle 1. The eight different tertiary carbon resonance
The metallacycles that contain a zirconiumꢀcarbon
s-bond are formed only from the complexes with a C1-,

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E.H. Licht et al. / Journal of Organometallic Chemistry 599 (2000) 261–274
C2- or Si-spacer moiety between the p-ligand and the
aromatic group (phenyl, fluorenyl and indenyl). Pre-
sumably, an interaction between the p-electrons of the
aromatic group and the free orbitals (LUMO) of the
d2-configurated zirconium with subsequent hydrogen
transfer onto the h2-butenyl ligand is only possible for
these spacers (Fig. 8).
In the case of a C3-spacer, an interaction of an
agostic hydrogen atom in the ortho position of the
phenyl group and a free orbital of zirconium is favored.
Presumably, a hydrogen transfer reaction to the
h2-butene ligand does not occur in this case for steric
reasons. Therefore, the typical resonance signals of
a h2-bonded butene ligand are found in the 13C-
NMR spectrum of metallacycle 3 at l=74.1 (CH),
60.9 and 45.6 (CH2) and l=14.2 ppm (CH3) (see
Table 2).
The p-coordinated metallocene complex 3 is stable in
solution and at higher temperatures (60°C). This stabil-
ity is analogous to that observed for the trimethylphos-
phine stabilized (h2-butene)(trimethylphosphine) zir-
conocene complex and is presumably due to the strong
interaction of the 1a1-orbital of zirconium with the
p*-orbital of the olefin [41] (Fig. 9).
Fig. 3. Overview of synthesized metallacycles 1–15a,b (only one isomer is illustrated for 14a,b and 15a,b).

E.H. Licht et al. / Journal of Organometallic Chemistry 599 (2000) 261–274
265
Fig. 4. Synthesis of metallacycle 16.
Fig. 5. Overview of synthesized metallacycles 17a,b–22a,b (only one isomer illustrated).
If spacer groups longer than C3 are present, the
2.5. Ethylene polymerization
spatial time-average proximity of the phenyl group to
the central metal is greatly reduced. Therefore, mixtures
of products, due to intra- and intermolecular reactions,
are likely to be formed.
The insertion of one methyl group in position 3 of
the v-phenylalkyl-substituted cyclopentadienyl ligand
suppresses the cyclometallation reaction. Approxi-
mately 80% cyclometallation reaction occurs with C1-
and C2-spacers (metallacycles 14a,b and 15a,b). A mix-
ture of products is produced with C3-spacers.
The metallacycle synthesis is obviously limited by
various structural parameters. However, a wide range
of metallacycles can be synthesized, using CH-activa-
tion and subsequent cyclometallation, from the wide
variety of available zirconium dichloride complexes.
The resultant metallacycles are suitable precursors
for homogeneous ethylene polymerization. The com-
plexes are activated by adding a 3000-fold molar excess
of MAO. The formation of an active catalyst system is
indicated by a color change.
To keep the length of the paper manageable, only
selected metallocene polymerization experimental data
are presented and compared with the results of the
corresponding metallocene dichloride complexes
[25,26]. The polymerization activities of the activated
metallacycles, the viscosity average molecular weights,
(
Mh, the fusion enthalpies, DHm, the melting tempera-
tures, Tm and the degree of crystallinity, h, of resulting
polyethylenes are listed in Table 1.

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E.H. Licht et al. / Journal of Organometallic Chemistry 599 (2000) 261–274
2.5.1. Influence of the spacer chain length on the poly-
merization beha6ior of symmetrically substituted metal-
locene dichloride complexes 1c–4c and deri6ed
lower than that of the uncyclized dichloride complex 4c.
These results demonstrate that the formation of metal-
lacycles from substituted bis(cyclopentadienyl) com-
plexes enhances their polymerization activity. The
polymerization activity, however, decreases if the metal-
lacycle cannot be formed and the chloro ligands are
only exchanged for alkyl ligands.
The polymerization activity increases considerably
for the metallocene dichloride complexes 1c–4c as well
as for the metallacycles 1–3 with increasing chain
length of the carbon spacer between the cyclopentadi-
enyl ligand and the bulky phenyl group. The reason for
this behavior may be the decreasing steric shielding of
the catalytic center by the phenyl group, due to longer
spacer chains, better separation of the MAO counter
ion from the active center of the cationic species or a
combination of these effects [42].
metallacycles 1–3
The chain length of the spacer has a strong impact on
the polymerization behavior of the synthesized metal-
locene complexes. Fig. 10 exhibits a comparison of the
homogeneous polymerization activities for the v-
phenylalkyl-substituted bis(cyclopentadienyl) zirconium
dichloride complexes 1c–4c and the analogous metalla-
cycles 1–3. Compared with the respective metallocene
dichloride complexes, the metallacyclic complexes have,
after activation with MAO, three to five times higher
polymerization activity. Reacting metallocene dichlo-
ride complex 4c with n-butyllithium does not form a
metallacycle due to its long spacer chain length (C4)
(see Section 2.4). After activation with MAO, the
unidentified product mixture 4* has very high polymer-
ization activity. However, the polymerization activity is
Fig. 11 exhibits the melting temperatures (Tm) of the
polymers synthesized with the metallocene dichloride
Fig. 6. 1H-NMR spectrum of metallocene complex 1 (in C6D6, 25°C).

E.H. Licht et al. / Journal of Organometallic Chemistry 599 (2000) 261–274
267
Fig. 7. J-mod. 13C{H}-NMR spectrum of metallocene complex 1 (in C6D6, 25°C).
complexes 1c–4c, the metallacycles 1–3 and the un-
known complex 4*. The Tm of the polyethylenes in-
creases with increasing chain length of the spacers
between the cyclopentadienyl ligand and bulky phenyl
group for the metallocene dichloride complexes 1c–4c
and the metallacycle derivatives 1–3. The melting tem-
peratures of the polymers produced with the complexes
1–3 are in all cases higher than those of the respective
noncyclic precursors 1c–3c.
compared in Fig. 12. They are significantly higher
(450–640 kg mol−1) than the molecular weights of the
polyethylenes obtained with symmetrically substituted
bis(cyclopentadienyl) metal complexes (290–360 kg
mol−1). The exchange of one v-phenylalkyl-substituted
cyclopentadienyl ligand by one non-substituted indenyl
ligand seems to reduce the chain termination rate inde-
pendent of the polymerization activity and therefore
leads to higher polyethylene molecular weights.
2.5.3. Influence of substituents on the ꢀ-phenyl group
on the polymerization beha6ior
The largest activity increase on going from the dichlo-
ride complex to the metallacycle is found for complexes
1c and 1, containing an unsubstituted benzyl group
2.5.2. Influence of the spacer chain length on the
polymerization beha6ior of the mixed substituted
metallocene dichloride complexes 9c–11c and the
metallacycle deri6ati6es 9–11
The activity of the mixed substituted metallocene
dichloride complexes 9c–12c and of the analogous
metallacycles 9–11 increases as the chain length of the
v-phenylalkyl group increases (Fig. 10). In comparison
with the symmetrically substituted metallocene dichlo-
ride complexes 1c–4c and metallacycles 1–3, the activ-
ity of the mixed substituted metallocene complexes
increases only modestly with increasing spacer chain
length. The reason for such a modest increase could be
the fact that the coordination sphere of the active
catalyst center is only influenced by one v-phenylalkyl
group. In contrast to the symmetrical metallocene com-
plexes, the polymerization activities of metallocene com-
plexes 9c and 9, containing a C1-spacer, are higher than
those for the metallocene complexes 10c and 10 contain-
ing a C2-spacer. This indicates a complex relationship
between the steric influence on the catalytic center by
the substituent and the separation of the contact ion
pair metallocene monoalkyl cation–MAO anion [42].
The molecular weights of the polyethylenes produced
with the metallocene complexes 9c–12c and 9–11 are
Fig. 8. Scheme for the intramolecular CH-activation with subsequent
cyclometallation reaction. (To keep the overall view, the second
p-ligand (beneath the paper plane) is not shown.)
Fig. 9. Stabilizing interaction of the 1a1-orbital of zirconium with the
p*-orbital of the olefin [41].

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E.H. Licht et al. / Journal of Organometallic Chemistry 599 (2000) 261–274
Table 1
Overview of the polymerization experiments a and polymer analytic results
c
Activity b
Mh (kg mol−1
)
DSC
(
Complex (catalyst precursor)
Tm (°C)
DHm (J g−1
)
h (%) d
1
2
3
4
5
6
8
9
10
790.4
1810.7
5577.0
1231.6
1040.0
1413.7
164.5
2850.0
2460.0
4560.0
100.7
1325.0
1509.0
131.6
2222.9
878
360
290
350
330
510
520
650
450
610
450
590
770
360
500
620
580
133.1
142.2
137.2
135.7
136.4
124.8
142.0
141.1
134.0
136.1
138.9
139.6
138.2
136.0
135.3
131.4
188.2
212.2
137.9
147.5
154.1
170.1
131.9
144.5
156.0
152.6
137.0
137.5
142.6
153.8
148.7
148.1
64.9
73.2
47.6
50.9
53.1
58.7
45.5
49.8
53.8
52.6
47.3
47.4
49.2
53.0
51.3
51.1
11
13
14a,b
19a,b
20a,b
21a,b
22a,b
a Tp=60°C; solvent: 500 ml pentane; 10 bar ethylene pressure.
b [M]/[Al]=1:3000.
c Intrinsic viscosity.
d Degree of crystallinity relative to the fusion enthalpy of 100% crystalline polyethylene.
Fig. 10. Comparison of the polymerization activities for the metallocene dichloride complexes 1c–4c and 9c–12c and the metallacycles 1–4 and
9–11. Reaction of 4c with two equivalents of n-butyllithium leads to an unidentified mixture of products 4*.
(Fig. 13). In contrast, a negative cyclization effect (tran-
sition from the metallocene dichloride complex to the
metallacycle) is observed for the 4-methylbenzyl-substi-
tuted metallocene complexes 4c and 4. The reason for
these behavioral differences seems to be the methyl
group in position 4. The additional methyl group in
position 4 of the phenyl group has no steric influence
on the active catalyst center. However, it can increase
the distance to the MAO counter ion [42]. For metalla-
cycles 1 and 4, one benzyl or one 4-methylbenzyl sub-
stituent is removed from the coordination sphere of the
center metal by incorporation into a polymer chain.
Therefore, there is less steric hindrance. Simulta-
neously, the metallocene monoalkyl cation–MAO an-
ion contact ion pair is less effectively separated. The
combination of these two effects has the most influence
on the metallacycle containing
substituent.
a 4-methylbenzyl
The 3,5-dimethyl-substituted and the benzoanellated
benzyl substituents of metallocene complexes 6c and 6
or 7c and 7 have steric influence on the active catalyst
center as well as on the extent of separation of the
MAO counter ion. Both dichloride complexes 6c and 7c
that possess comparable activities are lower in activity
than the 4-methyl-substituted complex 4c. A slightly
positive (naphthyl group) or a slightly negative cycliza-

E.H. Licht et al. / Journal of Organometallic Chemistry 599 (2000) 261–274
269
tion effect is observed for the polymerization activities
of the analogous metallacycles.
complexes 7c and 7 or 6c and 6 containing sterically
more demanding 3,5-dimethylbenzyl and naphthyl-2-
methyl substituents produce polymers with significantly
higher molecular weights in the range 490–590 kg
mol−1. Presumably, a reduction in the b-H-elimination
reaction during polymerization is the cause of the
higher molecular weights for the sterically burdened
metallocene complexes.
Fig. 14 exhibits the molecular weights for the
polyethylenes obtained with the benzyl-substituted
metallocene complexes. The molecular weights for the
polymers synthesized with the benzyl- and the 4-
methylbenzyl-substituted metallocene complexes 1c and
1 or 4c and 4 are 310–360 kg mol−1. The metallocene
Fig. 11. Melting temperatures Tam) of the polymers synthesized with the metallocene dichloride complexes 1c–4c and the metallocene complexes
1–3 and 4*. (a) The values are taken from the second heating course of DSC. (b) Reaction of 4c with two equivalents of n-butyllithium leads to
an unidentified mixture of products 4*.
Fig. 12. Comparison of the molecular weights of the polyethylenes synthesized by mixed substituted metallocene complexes and the corresponding
metallacycles.
Fig. 13. Dependency of the polymerization activity on the substituents on the phenyl group for the corresponding metallocene complexes.

270
E.H. Licht et al. / Journal of Organometallic Chemistry 599 (2000) 261–274
Fig. 14. Dependency of the molecular weights of the obtained polyethylenes on the substituents of the phenyl group of the corresponding
metallocene complexes.
Fig. 15. Influence of the substitution of one ligand on the polymerization activity of the metallocene complexes 9, 21a,b and 14a,b and the
molecular weights of the obtained polymers.
2.5.4. Influence of the substituents on the
der argon and measured at 25°C. The chemical shifts in
1H-NMR spectra are referred to the residual proton
signal of the solvent (l=7.15 ppm for benzene) and in
13C-NMR spectra to the solvent signal (l=128.0 ppm
for benzene-d6).
cyclopentadienyl ligand on the polymerization beha6ior
Substitution of the cyclopentadienyl ligand has great
impact on the polymerization activity of the corre-
sponding metallocene complex and on the molecular
weight of the obtained polyethylene. The polymeriza-
tion activity decreases when the cyclopentadienyl ligand
(9) is substituted, by an indenyl ligand (21a,b) or a
3-methyl-substituted cyclopentadienyl ligand (14a,b)
(Fig. 15). The opposite effect is observed for the mole-
cular weights of the obtained polyethylenes: the growing
polymer chain is obviously kept away from the coordi-
nation center by the steric demand of the benzene ring
or the methyl group. Therefore, a chain termination
reaction by b-H-elimination could be inhibited.
3.2. Mass spectroscopy
Routine measurements were performed using a
Varian MAT CH7 instrument (direct inlet, electron
impact ionization 70 eV). GC–MS spectra were
recorded using a Varian 3700 gas chromatograph in
combination with
spectrometer.
a
Varian MAT 312 mass
3.3. Gas chromatography
Organic compounds were analyzed with a Carlo-Erba
HRGC gas chromatograph with flame ionization detec-
tor. The J & W fused silica column was 30 m long, had
a diameter of 0.32 mm and a film thickness of 0.25 mm.
Helium served as the carrier gas. The following temper-
ature program was used:
3. Experimental
3.1. NMR spectroscopy
Bruker ARX 250, AC 300 and DRX 500 spectrome-
ters were available for the recording of the NMR
spectra. The organometallic samples were prepared un-
Starting phase: 3 min at 50°C

Table 2
1H- a, 13C- b and 29Si- c NMR data of the metallocene complexes 1–22a,b
a
Complex
1H-NMR (J(H,H) in Hz)
13C-NMR b
1
7.51 (m, 1H),7.25–6.85 (m, 8H), 6.56 (m, 1H), 6.12 (m, 1H), 5.98 (m, 1H), 5.89 (m, (Cq): 186.0, 166.3, 141.2, 139.6; (CH): 136.4, 128.9, 128.6, 128.4, 126.8, 126.4, 125.0,
2H), 5.85 (m, 1H), 5.49 (m, 1H), 5.08 (m, 1H), 4.03 (d, 1H) [16.7], 3.90 (d, 1H)
[16.7], 3.53 (s, 2H), 1.67 (m, 2H), 1.35 (m, 2H), 1.02 (t, 3H) [7.3], 0.90 (m, 1H),
0.52 (m, 1H)
123.2, 115.7, 113.1, 111.9, 111.2, 109.8, 108.7, 103.1; (CH2): 58.8, 38.2, 38.2, 36.3, 35.1;
(CH3): 14.1
2
3
4
7.23–7.00 (m, 9H), 6.26 (m, 1H), 5.71 (m, 3H), 5.43 (m, 2H), 5.26 (m, 1H), 4.96
(m, 1H), 2.83–2.65 (m, 4H), 2.44 (m, 2H), 2.18 (m, 1H), 1.84 (m, 1H), 1.56 (m,
2H), 1.46 (m, 2H), 1.09 (m, 4H), 0.69 (m, 1H)
7.27–6.82 (m, 10H), 6.52 (m, 1H), 5.59 (m, 3H), 5.44 (m, 2H), 5.26 (m, 1H), 4.84
(m, 1H), 2.80–1.04 (m, 15H), 0.74 (m, 1H), 0.23 (m, 1H)
(Cq): 188.9, 147.7, 141.9, 130.5; (CH): 128.8, 128.7, 128.6, 128.5, 127.3, 126.8, 126.4,
126.3, 123.6, 115.3, 114.5, 112.1, 109.3, 109.1, 106.9, 103.7, 103.4; (CH2): 55.0, 43.8, 38.7,
38.0, 35.3, 32.6, 32.2, 30.0, 29.9; (CH3): 14.2
(Cq): 151.8, 142.2, 141.4; (CH): 128.7, 128.6, 128.5, 128.3, 127.0, 126.1, 114.8, 112.9,
112.1, 111.0, 110.0, 109.8, 107.5, 102.9, 74.1; (CH2): 60.9, 45.6, 35.6, 35.4, 33.8, 29.9,
29.3, 29.0; (CH3): 14.2
/
7.51 (m, 1H),7.24–6.85 (m, 6H), 6.56 (m, 1H), 6.13 (m, 1H), 5.98 (m, 1H), 5.88 (m, (Cq): 186.1, 163.3, 139.8, 138.2, 135.6, 131.5; (CH): 137.0, 129.3, 128.9, 127.7, 124.8,
2H), 5.84 (m, 1H), 5.48 (m, 1H), 5.08 (m, 1H), 4.02 (d, 1H) [16.7], 3.90 (d, 1H)
[16.7], 3.53 (s, 2H), 2.29 (s, 3H), 2.18 (s, 3H), 1.67 (m, 2H), 1.35 (m, 2H), 1.02 (t,
3H) [7.3], 0.90 (m, 1H), 0.52 (m, 1H)
115.6, 113.1, 111.8, 111.2, 109.9, 109.8, 103.1; (CH2): 58.7, 37.4, 36.0, 35.5, 29.7; (CH3):
21.1, 21.0, 14.1
5
6
7.51 (m, 1H),7.23–6.72 (m, 6H), 6.50 (m, 1H), 6.13 (m, 1H), 5.98 (m, 1H), 5.92 (m, (Cq): 186.8, 163.8, 161.8, 159.9, 157.8, 140.0, 137.1; (CH2): 130.3, 130.2, 115.7, 115.4,
1H), 5.70 (m, 1H), 5.69 (m, 1H), 5.40 (m, 1H), 5.03 (m, 1H), 3.93 (d, 1H) [16.7],
3.75 (d, 1H) [16.7], 3.31 (s, 2H), 1.57 (m, 2H), 1.37 (m, 2H), 1.05 (t, 3H) [7.3], 0.99 14.0
(m, 1H), 0.44 (m, 1H)
115.1, 113.4, 112.1, 111.2, 109.9, 109.8, 108.7, 103.2; (CH2): 60.6, 36.9, 34.9, 29.7; (CH3):
7.24–6.66 (m, 5H), 6.46 (m, 1H), 5.92 (m, 3H), 5.83 (m, 2H), 5.45 (m, 1H), 5.11
(m, 1H), 3.95 (d, 1H) [16.6], 3.74 (d, 1H) [16.6], 3.52 (d, 1H) [16.6], 3.39 (d, 1H)
(Cq): 180.8, 160.4, 142.8, 140.9, 138.0, 137.8, 136.4, 136.0; (CH): 128.5, 127.1, 127.0,
126.9, 126.7, 123.4, 117.9, 112.8, 110.3, 110.2, 110.1, 110.0, 101.9; (CH2): 56.9, 37.8, 35.9,
[16.6], 2.37–2.20 (m, 12H), 1.72 (m, 2H), 1.42 (m, 2H), 1.07 (m, 4H), 0.32 (m, 1H) 33.4, 29.8; (CH3): 25.9, 21.4, 21.3
8.13 (2, 1H),7.95–7.03 (m, 12H), 6.50 (m, 1H), 6.18 (m, 1H), 6.07 (m, 1H), 5.92 (m, (Cq): 185.8, 162.7, 140.3, 138.6, 134.1, 133.3, 132.8, 131.0; (CH): 135.2, 128.8, 128.3,
1H), 5.80 (m, 1H), 5.72 (m, 1H), 5.45 (m, 1H), 5.03 (m, 1H), 4.17 (d, 1H) [16.7],
128.2, 128.1, 128.0, 127.7, 127.6, 126.3, 125.9, 125.7, 125.0, 121.7, 115.2, 114.3, 112.3,
599
4.05 (d, 1H) [16.7], 3.70 (s, 2H), 1.68 (m, 2H), 1.36 (m, 2H), 1.04 (t, 3H) [7.3], 0.92 112.0, 109.7, 109.5, 109.0, 102.8; (CH2): 58.6, 37.8, 36.6, 35.6, 29.7; (CH3): 14.2
(m, 1H), 0.63 (m, 1H)
(
8 d
7.52–7.09 (m, 8H), 6.72 (m, 1H), 6.55 (m, 1H), 56.47 (m, 1H), 6.42 (m, 1H), 5.98
(m, 1H), 5.80 (m, 1H), 5.72 (m, 1H), 5.44 (m, 1H), 1.65 (m, 2H), 1.36 (m, 2H),
1.03 (t, 3H) [7.3], 0.70 (m, 1H), 0.57 (s, 3H), 0.45 (s, 3H), 0.43 (s, 3H), 0.36 (m,
1H), 0.35 (s, 3H),
(Cq): 194.3, 158.5, 139.0, 117.1; (CH): 134.8, 134.2, 132.6, 129.5, 128.1, 126.4, 125.4,
120.8, 120.4, 120.2, 120.1, 114.2, 113.9, 113.4, 108.1; (CH2): 58.9, 35.6, 29.6; (CH3): 14.0,
−0.4, −0.9, −1.6, −1.7
261
274
9
7.77 (m, 1H), 7.51 (d, 1H) [7.9], 7.20–6.75 (m, 6H), 6.47 (m, 1H), 6.33 (m, 2H),
(Cq): 185.8, 165.4, 138.9; (CH): 135.8, 126.8, 125.2, 125.1, 124.4, 124.3, 123.6, 123.0,
5.95 (m, 1H), 5.79 (m, 1H), 5,20 (m, 1H), 4.95 (m, 1H), 3.97 (d, 1H) [16.6], 3.77 (d, 117.0, 115.6, 112.9, 110.7, 105.3, 102.3, 97.6; (CH2): 62.1, 37.6, 35.4, 29.8; (CH3): 14.1
1H) [16.6], 1.48 (m, 2H), 1.29 (m, 2H), 1.04 (t, 3H) [7.2], 0.14 (m, 1H), −0.20 (m,
1H)
10
11
7.31–6.78 (m, 8H), 6.18 (m, 1H), 5.99 (m, 1H), 5.92 (m, 1H), 5.83 (m, 1H), 5,53
(m, 1H), 5.13 (m, 1H), 4.75 (m, 1H) 2.70 (m, 4H), 1.57 (m, 2H), 1.29 (m, 2H), 1.04 117.6, 115.6, 114.2, 113.6, 105.1, 100.7, 97.3; (CH2): 59.3, 43.6, 37.6, 30.1, 29.3; (CH3):
(t, 3H) [7.2], 0.20 (m, 1H), −0.07 (m, 1H)
7.31–6.73 (m, 7H), 6.40 (m, 2H), 6.02 (m, 1H), 5.84 (m, 1H), 5.54 (m, 1H), 5,48
(Cq): 188.4, 147.4, 130.7; (CH): 131.2, 128.6, 127.0, 126.8, 125.2, 124.8, 124.2, 124.1,
14.1
(Cq): 151.8, 140.5, 124.6; (CH): 129.3, 128.7, 128.6, 128.4, 127.5, 124.3, 124.2, 122.0,
(m, 1H), 4.94 (m, 1H), 4.84 (m, 1H) 2.76–0.76 (m 12H), −0.51(m, 1H), −0.65 (m, 114.8, 114.4, 110.4, 108.1, 104.4, 104.3, 96.3, 74.8; (CH2): 65.0, 46.1, 36.0, 30.5, 29.0;
1H) (CH3): 14.1

Table 2 (Continued)
a
Complex
1H-NMR (J(H,H) in Hz)
13C-NMR b
12
7.68 (m, 1H), 7.53 (d, 1H) [7.9], 7.20–6.79 (m, 5H), 6.48 (m, 1H), 6.39 (m, 2H), 6.02 (Cq): 186.0, 162.4, 139.2, 131.3; (CH): 136.4, 127.7, 125.1, 124.8, 124.4, 124.2, 123.7, 117.2,
(m, 1H), 5.82 (m, 1H), 5,20 (m, 1H), 4.95 (m, 1H), 3.90 (d, 1H) [16.6], 3.78 (d, 1H) 115.6, 112.9, 110.8, 105.3, 102.2, 97.9; (CH2): 61.9, 37.2, 35.5, 29.8; (CH3): 21.5, 14.0
[16.6], 2.35 (s, 3H), 1.48 (m, 2H), 1.27 (m, 2H), 1.00 (t, 3H) [7.1], 0.22 (m, 1H),
−0.08 (m, 1H)
13
7.65 (m, 1H), 7.45 (d, 1H) [7.9], 7.23–6.72 (m, 6H), 6.38 (m, 2H), 6.31 (m, 1H), 6.04 (Cq): 183.9, 172.6, 149.7, 43.8 (CH): 134.3, 129.3, 127.9, 125.3, 124.5, 124.1, 123.8, 123.5,
(m, 1H), 5.96 (m, 1H), 5,25 (m, 1H), 4.87 (m, 1H), 1.78–1.19 (m, 10H), 0.97 (t, 3H) 117.7, 116.1, 113.8, 103.7, 101.7, 98.3 (CH2): 60.9, 54.1, 35.5, 29.8 (CH3): 31.7, 30.5, 14.0
[7.1], 0.21 (m, 1H), 0.00 (m, 1H)
14a,b
15a,b
7.71 (m, 1H), 7.46 (d, 1H) [7.9], 7.25–6.75 (m, 6H), 6.52 (m, 1H), 6.38 (m, 1H), 6.14 (Cq): 184.2, 164.8, 137.1, 125.7; (CH): 136.3, 127.2, 125.7, 125.5, 124.4, 124.0, 123.5, 123.1,
(m, 1H), 5.85 (m, 1H), 5,20 (m, 1H), 4.98 (m, 1H), 4.77 (m, 1H),3.92 (m, 2H), 1.93 118.5, 115.5, 111.6, 103.1, 101.0, 99.2; (CH2): 58.7, 36.3, 34.9, 30.0; (CH3): 14.0, 13.9
(s, 3H), 1.67 (m, 2H), 1.29 (m, 2H), 1.05 (t, 3H) [7.2], 0.49 (m, 1H), −0.13 (m, 1H)
7.48–6.75 (m, 16H), 6.19–5.83 (m, 6H), 5.74–5.39 (m, 4H), 5.05 (m, 1H), 4.75 (m,
(Cq): 189.7, 188.1, 147.8, 147.1, 146.9, 130.7; (CH): 132.2, 130.1, 128.8, 128.7, 126.9, 126.7,
/
1H), 2.71 (m, 4H), 2.24–0.97 (m, 24H), 0.28 (m, 1H), 0.05 (m, 1H), −0.12 (m, 1H), 125.0, 125.0, 124.9, 124.7, 124.2, 123.7, 123.3, 122.2, 116.0, 115.9, 114.0, 112.6, 112.1,
−0.28 (m, 1H)
106.7, 105.6, 105.2, 102.7, 100.2, 96.9, 95.2; (CH2): 59.6, 57.5, 43.7, 42.8, 36.2, 30.6, 30.5,
26.9; (CH3):14.1, 14.0
16
7.51 (m, 1H), 7.21–7.08 (m, 3H), 6.37 (m, 1H), 6.08 (m, 1H), 6.00 (s, 5H), 5.63 (m, (Cq): 183.2, 172.1, 150.7, 138.2, 43.1; (CH):135.2, 128.3, 126.7, 126.5, 123.7, 114.2, 113.6,
1H), 5.12 (m, 1H), 1.82–1.24 (m, 10 H), 0.99 (t, 3H) [7.3], 0.54 (m, 2H)
110.5, 105.5, 100.8; (CH2): 59.3, 37.7, 29.8; (CH3): 32.0, 30.4, 14.1
17a,b
7.63 (d, 1H) [7.9], 7.31–6.71 (m, 38 H), 6.48 (m, 1H), 5.73 (m, 1H), 5.12 (m, 1H),
(Cq): 184.8, 184.5, 165.6, 165.4, 142.2, 141.1, 121.6, 120.4, 112.8, 111.1; (CH): 136.8, 136.3,
4.39–3.62 (m, 8H), 1.45–0.81 (m, 14H), −0.28 (m, 1H), −0.84 (m, 1H), −1.20 (m, 129.2, 128.9, 128.8, 128.6, 128.5, 126.7, 126.5, 126.4, 126.0, 125.6 125.5, 125.4, 125.0, 124.8,
1H), −0.41 (m, 1H)
124.7, 124.6, 124.4, 124.1, 124.0, 123.9, 123.6, 123.5, 123.4, 123.3, 123.2, 123.1, 120.9,
120.8, 103.5, 101.9, 96.2, 93.8; (CH2): 64.9, 62.5, 38.1, 36.7, 36.4, 34.7, 33.8, 33.7, 30.8,
30.4; (CH3): 14.0, 13.9
18a,b
19a,b
7.53–6.55 (m, 40 H),), 5.73 (m, 1H), 5.12 (m, 1H), 2.93–1.52 (m, 16H), 1.47–0.79 (m, Not determined
14H), −0,13 (m, 1H), −0.73 (m, 1H), −1.11 (m, 1H), −0.62 (m, 1H)
7.43–6.91 (m, 36H), 6.51 (m, 2H), 6.01–5.91 (m, 4H), 5.67 (d, 1H) [3.2], 5.50 (d, 1H) (Cq): 141.9, 141.8, 141.6, 116.3, 116.1, 115.9, 103.9; (CH): 128.9, 128.7, 128.6, 126.3, 126.2,
[3.2], 2.89–2.45 (m, 12H), 1.96–0.88 (m, 20H), 0.36 (m, 2H), −0.97 (m, 2H)
126.1, 126.0, 125.0, 124.9, 124.8, 124. 7, 124.3, 124.2, 124.0, 123.9, 123.8, 98.7, 98.5, 49.7,
47.5, 46.8; (CH2): 63.1, 58.8, 54.0, 36.4, 35.8, 34.6, 33.2, 31.2, 30.0, 28.5, 27.4, 27.1; (CH3):
10.3, 10.1
599
(
20a,b e
7.23–6.51 (m, 36H), 6.36 (m, 1H), 6.23 (m, 2H), 5.63 (m, 1H), 5.59 (m, 2H), 1.33–
0.34 (m, 38 H), −0.96 (m, 1H), −1.27 (m, 1H), 1.31 (m, 1H), −1.98 (m, 1H)
(Cq): −194.6, 192.8, 161.1, 155.8, 139.7, 138.4, 136.7, 133.9, 131.5, 131.1, 130.3, 130.0,
114.4, 104.9; (CH): 134.9, 134.2, 134.1, 134.0, 129.3−120.6 (m), 119.7, 114.2, 111.0, 10.6,
101.2, 91.5; (CH2): 69.2, 66.3, 40.8, 36.9, 35.7, 31.9, 30.1, 26.6; (CH3): 13.7, 13.5, 10.7,
10.6, 2.2, −0.4, −0.5, −0.6
261
274
21a,b
7.34–6.95 (m, 15 H), 6.32 (d, 1H) [6.4], 4.,78 (d, 1H) [11.5], 4.20 (d, 1H) [16.8], 3.91 (Cq): 184.4, 165.6, d; (CH): 136.9, 128.8, 128.6, 126.7, 125.6, 125.4, 125.3, 124.9, 124.8,
(d, 1H) [16.8], 1.51–0.90 (m, 7H), −0.63 (m, 1H), −1.53 (m, 1H)
7.41–6.32 (m, 14H), 6.66 (m, 1H), 5.16 (d, 1H) [3.0], 5.01 (d, 1H) [2.4], 1.58–0.95 (m, (Cq): 193.3, 158.3, 131.9, 129.9, 114.2; (CH): 136.2, 134.5, 132.4, 128.2, 126.9, 126.5, 125.7,
124.5, 124.0, 123.3, 123.2, 120.3, 119.1; (CH2): 63.9, 36.5, 36.4, 30.6; (CH3): 14.0
22a,b e
7H), 0.75 (s, 3H), 0.45 (s, 3H), −0.19 (m, 1H), −1.60 (m, 1H)
125.6, 125.3, 125.0, 124.7, 120.4, 102.9, 102.6, 100.1; (CH2): 65.5, 37.5, 31.1; (CH3): 14.0,
−0.7, −0.9
a 25°C, in benzene-d6 l [ppm] rel. benzene (7.24).
b 25°C, in benzene-d6 l [ppm] rel. benzene-d6 (77.0).
c 25°C, in benzene-d6 l [ppm] rel. TMSext. (0.0).
d l (Si)=−9.9, 11.6 ppm.
e l (Si)=−10.5 ppm.

E.H. Licht et al. / Journal of Organometallic Chemistry 599 (2000) 261–274
273
Heating phase: 5°C min−1 (15 min)
Plateau phase: 310°C (15 min)
fusion enthalpy of indium (Hm=28.45 J g−1) was used
for calibration.
3.7.2. Viscosimetry
3.4. General synthesis procedure for the metallocene
complexes 1–22a,b
The molecular-weight determination of the
polyethylene samples was performed using an Ubbel-
ohde precision capillary viscometer in cis/trans decalin
at 13590.1°C. For the measurements, 50 mg polymer
were completely dissolved in 45.0 ml decalin at 130°C
within 3–4 h and insoluble ingredients filtered over
The metallocene dichloride complex, 3.00 mmol, was
dissolved in 50 ml toluene and at −78°C mixed with
3.8 ml (6.0 mmol) n-butyllithium. The reaction mixture
was warmed to room temperature over 6 h and stirred
overnight. The reaction mixture was filtered over
sodium sulfate, and the solvent evaporated in vacuo.
The metallocene complexes were obtained as yellow oils
or solids in 60–98% yields and were characterized by
NMR spectroscopy (Table 2).
(
glass wool. Mh was determined using a calibration
curve that was available for the selected concentration.
Acknowledgements
We thank the Deutsche Forschungsgemeinschaft, the
Alexander von Humboldt Foundation and Phillips
Petroleum Company (Bartlesville, OK, USA) for the
financial support and Witco Company for the supply of
MAO.
3.5. Acti6ation of the metallocene complexes with
MAO
The desired metallocene complex, 10–15 mg, was
activated with MAO (30% in toluene) (Zr:Al=1:3000).
A volume of the catalyst solution contained 0.5–1.5 mg
metallocene complex and was used within 1 h for
homopolymerization.
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