Synthesis, characterization, and catalytic properties of ansa-zirconocenes [Zr{1-Me2Si(3-η5-C9H5R) 2}Cl2] (R = Me, nPr, nBu, and Bz)

Article abstract of DOI:10.1002/ejic.200500845

The ansa-indene ligands {1-Me₂Si(3-C₉H ₆R)₂} [R = Me (1), nPr (2), nBu (3), and Bz (4)] were prepared by alkylation of the unsubstituted ansa-indene. These ligands were converted, by reaction with nBuLi, to the

Full text of DOI:10.1002/ejic.200500845

FULL PAPER
DOI: 10.1002/ejic.200500845
Synthesis, Characterization, and Catalytic Properties of ansa-Zirconocenes
[Zr{1-Me2Si(3-η5-C9H5R)2}Cl2] (R = Me, nPr, nBu, and Bz)
Carlos Alonso-Moreno,[a] Antonio Antiñolo,[a] Fernando Carrillo-Hermosilla,[a]
Antonio Otero,*[a] Ana M. Rodríguez,[a] José Sancho,[b] Victoria Volkis,[c] and Moris Eisen[c]
Dedicated to Professor Victor Riera on the occasion of his 70th birthday[‡]
Keywords: Metallocenes / Zirconium / Homogeneous catalysis / Polymerization / Ethylene
The ansa-indene ligands {1-Me2Si(3-C9H6R)2} [R = Me (1),
nPr (2), nBu (3), and Bz (4)] were prepared by alkylation of
the unsubstituted ansa-indene. These ligands were con-
verted, by reaction with nBuLi, to the di-lithium compounds
[Li2{1-Me2Si(3-C9H5R)2}] [R = Me (5), nPr (6), nBu (7), and Bz
(8)]. ansa-Zirconocenes, [Zr{1-Me2Si(3-η5-C9H5R)2}Cl2] [R =
Me (9), nPr (10), nBu (11), and Bz (12)], have been prepared
by the reaction of ZrCl4 with 5–8 in diethyl ether/toluene at
–78 °C. The molecular structure of meso-[Zr{1-Me2Si[3-η5-
crystal X-ray diffraction studies. Ethylene polymerization ca-
talysis has been studied for complexes 9–12 as a mixture of
meso and rac isomers in the presence of methylaluminoxane
(MAO) as cocatalyst. Complexes 9–12 exhibit high activities
and give rise to polyethylene with low molecular weights
without the introduction of molecular hydrogen. In addition,
active species from these complexes were found to be very
stable in comparison with unsubstituted analogues.
C9H5(CH3)]2}Cl2]
(9)
and
rac-[Zr{1-Me2Si[3-η5-C9H5-
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2006)
(CH2CH2CH3)]2}Cl2] (10) have been determined by single-
indenyl group has been studied,[4] few examples of ansa-bis-
indenyl complexes, bearing SiMe2 bridges, have been de-
scribed[5–9] and, to the best of our knowledge, there is not
a complete structural characterization of these complexes.
The target for these catalysts was to study the influence of
the metallocene structure in the performance of propylene
polymerization. Less attention has been paid to the study
of the influence on the properties of the polyethylene ob-
tained with these catalysts, i.e., on the molecular weight of
the obtained polymer. Usually, this parameter can be con-
trolled during the polymerization by either adjusting the
temperature of the polymerization or by adding molecular
hydrogen, which acts as a chain transfer agent.[10]
Introduction
A large number of new catalysts for olefin polymeriza-
tion, classified as metallocene catalysts, have been prepared
during the last decade.[1] The majority of these catalysts
consist of a zirconium complex with the general formula
LLЈZrCl2 and these systems are activated by methylalumin-
oxane (MAO). The ligands L and LЈ are typically equal or
different dienyl ligands that may be linked together by a
bridge. A major evolution has been achieved in the field of
polypropylene, which can now be produced with different
types and degrees of stereoregularity.[2] In fact, a new class
of catalysts based on C2-symmetric metallocenes, with ansa-
bis(indenyl) ligands, produce almost isotactic polypropyl-
enes. The best-known example is Brintzinger’s rac-[Zr{1-
(C2H4)(η5-C9H6)2}Cl2].[3] Although the introduction of an
alkyl substituent in the cyclopentadienyl fragment of the
With this in mind, and as part of our continued interest
in this field,[11] we have developed new examples of ansa-
zirconocene catalysts of the general formula [Zr{1-Me2Si(3-
η5-C9H5R)2}Cl2]. These catalysts have proved to be very
active and are able to produce polyethylene with low mol-
[a] Departamento de Química Inorgánica, Orgánica y Bioquímica,
Facultad de Ciencias Químicas, Universidad de Castilla-La ecular weight without introducing molecular hydrogen to
Mancha, Campus Universitario de Ciudad Real,
control the process. It was of particular interest to compare
13071 Ciudad Real, Spain
the results with the analogous unsubstituted complex [Zr{1-
E-mail: Antonio.Otero@uclm.es
Me2Si(η5-C9H6)2}Cl2].[12]
Fernando.Carrillo@uclm.es
[b] Centro Tecnológico Repsol-YPF,
Here we provide the details of the preparation and poly-
merization behavior of four members of this class of cata-
lysts [Zr{1-Me2Si(3-η5-C9H5R)2}Cl2] [R = Me (9), nPr (10),
nBu (11), and Bz (12)]. The activities of these systems in
the polymerization of ethylene and the molecular weights
Carretera de Extremadura, Km. 18, 28931 Móstoles, Spain
[c] Department of Chemistry and Institute of Catalysis Science and
Technology Technion, Israel Institute of Technology,
Haifa 32000, Israel
[‡] In recognition of his important contribution to organometallic
chemistry and as a mark of friendship.
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ansa-Zirconocenes
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of the resulting polymers are discussed. In addition, the
molecular structures of rac-10 and meso-9 have been deter-
mined by X-ray diffraction methods.
Results and Discussion
The preparation of the substituted ansa-indene precur-
sors {1-Me2Si(3-C9H6R)2} [R = Me (1), nPr (2), nBu (3)
and Bz (4)] was achieved by alkylation of the dilithium salt
of {1-Me2Si(3-C9H7)2}, generated with nBuLi in Et2O, with
a large excess of RX (X = I and R = Me for 1, X = Br and
R = nPr for 2, X = Br and R = nBu for 3, and X = Br and
R = Bz for 4) (Scheme 1). Column chromatography was
used to purify the ligands 1–4.
Scheme 2.
While the total yield of this last step is satisfactory, a
random rac/meso ratio is obtained. In general, the rac/meso
ratio ranges from 0.6:1 (10) to 1.86:1 (12). For complex 9,
samples of the pure meso diastereomer and a product en-
riched in the rac isomer (11.5:1) were obtained by careful
recrystallization from CH2Cl2/Et2O.
Scheme 1.
1
The H NMR spectra for the meso isomers of the com-
plexes 9–12 show the following signals: two singlets for the
This is the preferred route because of the very simple ansa-bridge methyl groups, a singlet for the proton of the
synthesis and purification of the intermediate {1-Me2- indenyl C5 ring, and four multiplets corresponding to the
Si(C9H7)2} and because of its intrinsic versatility. In fact, protons of the C6 ring of the indenyl moiety. In addition,
{1-Me2Si(C9H7)2} is a convenient starting material for the the appropriate signals were observed for the pendant alkyl
synthesis of a series of different 3-alkyl- and 3-silyl-ansa- chain (see Exp. Sect.). Furthermore, the following signals
1
bisindenyl ligands.[13]The H NMR spectra show the meso- were observed for the rac isomers of the complexes 9–12: a
isomer as the major isomer for derivatives 1–4, with two singlet for the ansa-bridge methyl groups, a singlet for the
singlets for the ansa-bridge methyl groups, a doublet for proton of the indenyl C5 ring, and four multiplets corre-
H1, a doublet for H2, and four multiplets corresponding to sponding to the protons of the C6 ring of the indenyl moi-
the protons of the C6 ring of the indenyl moiety. In ad- ety. In addition, several signals were observed for the pen-
dition, the corresponding signals were observed for the pen- dant alkyl chain (see Exp. Sect.).
dant alkyl chain (see Exp. Sect.).
1H NMR nuclear Overhauser effect (NOE) difference
As shown in Scheme 2, the deprotonation of 1–4 with spectroscopy allowed unambiguous identification of each
nBuLi gave the lithium salts [Li2{1-Me2Si(3-C9H5R)2}] [R isomer. Irradiation of the signal due to H2 in the meso iso-
= Me (5), nPr (6), nBu (7), and Bz (8)]. The subsequent mer (which appears as a singlet in the NMR spectrum) led
reaction of the lithium salts with ZrCl4, in diethyl ether/ to measurable enhancement of the protons of the C3-alkyl
toluene, gave the corresponding zirconocene complexes substituent and the protons in one of the methyl groups of
[Zr{1-Me2Si(3-η5-C9H5R)2}Cl2] [R = Me (9), nPr (10), nBu the SiMe2 bridge. However, a similar irradiation in the rac
(11), and Bz (12)]. The orange solids obtained are sensitive isomer led to enhancement of the corresponding signals due
towards air and moisture and are soluble in polar solvents. to the C3-alkyl and the silicon methyl groups as well as the
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A. Otero et al.
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aromatic proton H7 on the opposite indenyl ring (Figure 1). Table 1. Selected bond lengths [Å] and angles [°] for meso-9 and
rac-10.
In the meso isomer, these SiMe2 methyl groups are located
in very different chemical environments (one is sandwiched
between the two C6 aromatic rings, and the other is only
flanked by the Cp rings), while in the rac isomer the two
methyl groups are equivalent.
meso-9
rac-10
Bond lengths
Zr(1)–Cent(1)[a]
Zr(1)–Cent(2)[b]
av[c] Zr(1)–C[Cent(1)][a]
av[c] Zr(1)–C[Cent(2)][b]
Zr(1)–Cl(1)
2.246(1)
2.252(1)
2.550(6)
2.556(6)
2.409(2)
2.4375(19)
2.448(6)
2.467(6)
2.631(6)
2.662(6)
2.540(6)
2.243
2.548(3)
2.4130(11)
Zr(1)–Cl(2)
Zr(1)–C(1)
Zr(1)–C(2)
Zr(1)–C(3)
Zr(1)–C(4)
Zr(1)–C(5)
2.451(3)
2.483(3)
2.619(3)
2.656(3)
2.529(3)
Bond angles
Cent(1)[a]–Zr–Cent(2)[b]
Si(1)–C(1)–Cent(1)[a]
Si(1)–C(11)–Cent(2)[b]
Cl(1)–Zr–Cent(1)[a]
Cl(1)–Zr–Cent(2)[b]
Cl(2)–Zr–Cent(1)[a]
Cl(2)–Zr–Cent(2)[b]
128.84
163.6(4)
163.5
106.71
106.65(5)
106.40
106.97
128.81
163.5
1
Figure 1. H NOE difference experiments provide information on
106.76(3)
106.82(2)
the spatial proximity between protons.
The carbon signal assignments were made following a
procedure on the basis of 1H and 13C NMR correlated spec- [a] Cent(1) is the centroid of C(1)–C(5) for both complexes.
[b] Cent(2) is the centroid of C(11)–C(15) for the complex meso-9.
troscopy (HETCOR) (see Exp. Sect.). For the meso isomer
[c] Refers to the average bond length between Zr(1) and the carbon
of these compounds 9–12, the 13C analysis showed two sig-
atoms of the C5 ring of the cyclopentadienyl moiety.
nals for the ansa-bridge methyl groups, a signal for the car-
bon C2 of the indenyl C5 ring, and four signals correspond-
observed previously for other bis(indenyl)-zirconium di-
chlorides [2.407(1)–2.465(2) Å].[15–20]
ing to the carbons (C4–C7) of the C6 ring of the indenyl
moiety. For the rac isomers, only one signal was found for
the ansa-bridge methyl groups. In addition, a signal of the
carbon C2 of the indenyl C5 ring was observed, and four
signals corresponding to the carbons (C4–C7) of the C6
ring of the indenyl moiety. The corresponding signals were
observed for the pendant alkyl chain for both isomers (see
Exp. Sect.).
The angles between some relevant planes are collected in
Table 2 along with the geometrical parameters described in
Figure 3 for compounds meso-9, rac-10, and the unsubsti-
tuted parent rac-[Zr{1-Me2Si(η5-C9H6)2}Cl2].[12] As usual
for bent metallocenes, the overall coordination environment
is best described by the set of parameters depicted in Fig-
ure 3, which describes the metal accessibility. In particular,
the smaller the “bite angle” β and the larger the Cp–M–
CpЈ α angle, the more the metal is tucked into the ligand
envelope.
X-ray Molecular Structures of Complexes meso-9 and rac-
10
The main geometrical difference of meso-9 and rac-10
Single crystals of meso-9 and rac-10 that were suitable from rac-[Zr{1-Me2Si(η5-C9H6)2}Cl2] is associated with the
for X-ray diffraction were obtained from CH2Cl2/ether and angle β and the range of Zr–CCp bond lengths. β, in meso-
toluene. Their molecular structures, as determined by the 9 (63.9°) and rac-10 (62.9°), is increased compared to that
crystallographic analysis, are depicted in Figure 2.
of rac-[Zr{1-Me2Si(η5-C9H6)2}Cl2] (60.2°). The range of
The meso-9 complex crystallizes in the triclinic space Zr–CCp for both complexes (0.21 Å for meso-9 and 0.20 Å
group P1. The crystal structure reveals the existence of one for rac-10) is similar to that in rac-[Zr{1-Me2Si(η5-
¯
unique isomer. The rac-10 complex crystallizes in the mo- C9H6)2}Cl2] (0.20 Å).
noclinic space group P2/c with a solvate toluene molecule.
These differences are, likely, caused by the bulky R sub-
The crystal structure reveals the existence of two racemic stituents at C(3) of both indenyl fragments. This conclusion
enantiomers. The bonding parameters for meso-9 and rac- is supported by significant displacements of the C(3)–R
10 are summarized in Table 1. The mutual arrangement of bonds from the planes of the parent cyclopentadienyl rings
the indenyl fragments corresponds to C2 symmetry for rac opposite to Zr (4.1° and 4.5° for meso-9, and 4.2° for rac-
and Cs for meso.
10).
It can be seen from Figure 2 that, for the structures of the
In both cases the zirconium atom is in a pseudotetrahe-
dral environment formed by the two chloride ligands and complexes meso-9 and rac-10, both C5 rings are eclipsed,
two η5-coordinated indenyl ligands. The Zr–C bond lengths including, in the case of meso-9, the methyl-substituent in
of five-membered rings range between 2.448(6) and position 3. In meso-9, it can be observed that one of the
2.662(6) Å. These values are close to that found in other chloride ligands is very close to the C6 aromatic rings,
ansa-bis(indenyl) zirconocene complexes (2.5 Å).[14] The whereas the other one is in an intermediate location be-
Zr–Cl distances for these complexes are within the range tween the methyl-substituents. In the case of rac-10, each
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ansa-Zirconocenes
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Figure 2. Solid state structure of rac-10 and meso-9 (hydrogen atoms are omitted for clarity).
Table 2. Relevant geometrical parameters.[a]
meso-9
rac-10
rac-[Me2Si(Ind)2]ZrCl2
α
β
128.7
63.9
128.8
62.9
127.8
60.2
δ
φ
83.6, 83.4
95.3
83.9
95.3
85.7
94.4
γ
15.6, 15.8
2.45–2.66,
0.21
16.1
2.45–2.65,
0.20
17.8; 16.4
2.46–2.66, 0.20
r(Zr–CCp),
∆r
Figure 3. Schematic representation of an ansa-metallocene detail-
ing the angles listed in Table 2.
[a] All quantities in degrees, apart from ∆ (Å). The angles α, β, γ,
δ, and φ are defined in Figure 3. ∆ is the distance between the
perpendicular projection of the heavy atom on the ring least-
squares plane and the ring centroid.
established to control the molecular weight of the polymers
obtained.
chloride ligand is between a ring and an alkyl substituent.
This situation could give rise to a great influence of the
rings and their alkyl substituents on the positions occupied
Polyethylene Polymerization using Complexes 9–12
Complexes 9–12, used as rac/meso mixtures, after being
by the active sites of the catalysts. These features could be activated with methylaluminoxane (MAO), are very active
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Table 3. Homogeneous ethylene polymerization results for 9–12 and [Zr{1-Me2Si(η5-C9H6)2}Cl2] as reference. Conditions: 343 K, 1.5 bar
monomer pressure, 6 µmol Zr, MAO/Zr = 2000, 100 mL toluene, tpol = 30 min.
Complex
Activity[a]
[kgPE/molZr ×h]
Activity (after 12 h)[a][b] Mw
[kgPE/molZr ×h]
Mn
Mw/Mn
M.p.
[°C]
[gmol–1]
[Zr{1-Me2Si[3-(η5-C9H5)Me]2}Cl2] (9)
[Zr{1-Me2Si[3-(η5-C9H5)nPr]2}Cl2] (10)
[Zr{1-Me2Si[3-(η5-C9H5)nBu]2}Cl2] (11)
[Zr{1-Me2Si[3-(η5-C9H5)Bz]2}Cl2] (12)
[Zr{1-Me2Si(Ind)2}Cl2]
6333
3473
2946
1849
3573
1757
2333
1856
1843
82000
87000
74000
70000
166000
21000
26000
17000
17000
53000
3.82
3.40
4.35
4.06
3.16
132
134
132
134
136
No reaction
[a] Average value for three different runs. [b] Precatalyst/MAO solutions were aged for 12 h, at room temperature, before monomer
introduction.
catalysts for the polymerization of ethylene. In the present
Experimental Section
study, we used a 10% solution of MAO in toluene, which
General Remarks: All reactions were carried out using standard
contains about 20–30% of AlMe3. In all polymerization ex-
Schlenk-tube and glove-box techniques in dry nitrogen. Solvents
periments, Al(iBu)3 was used to scavenge possible impuri-
were distilled from appropriate drying agents and degassed before
use. ZrCl4, indene, SiMe2Cl2, ICH3, BrCH2CH2CH3,
BrCH2CH2CH2CH3, and BrCH2Ph were purchased from Aldrich
and used directly. 1H and 13C spectra were recorded with Varian
ties in the monomer. The polymerization results are com-
pared with those of one of the best zirconocene catalysts,
i.e., [Zr{1-Me2Si(η5-C9H6)2}Cl2].[12] The polymerization re-
sults and the available polymer characterization data are GEMINI FT-400 and Varian INNOVA FT-500 spectrometers and
referenced to the residual deuterated solvent. Microanalyses were
carried out with a Perkin–Elmer 2400 microanalyzer. Mass spec-
trometry was performed with a Hewlett–Packard 5988A (m/z =
50–1000) (electron impact) spectrometer.
shown in Table 3.
Complexes 9–12 show similar or higher activities than
the reference complex and, moreover, these new catalysts
produced lower molecular weight polyethylene than the ref-
erence catalyst. Although it is not possible to establish any
relation between the size of the substituent and the polymer
molecular weight, we suggest that this low molecular weight
arises due to the steric influence of the substituents. The
activities of complexes 9–12 decrease as the bulk of the sub-
stituent in position 3 increases.
In addition, the melting points of all the polymers were
determined (see Table 3). The catalysts 9–12 produced crys-
talline materials with relatively high melting points (near
130 °C).
The stability of metallocene complexes is one of the most
important variables for its future industrial use. The activi-
ties of activated forms of complexes 9–12 were tested after
12 h of contact between the complexes and MAO solution.
It is worth noting that these complexes maintained a rea-
sonable level of activity after this contact time. In contrast,
the reference complex ([Zr{1-Me2Si(η5-C9H6)2}Cl2]) did
not give any reaction with ethylene after the same time of
contact with MAO. It therefore appears that an increase in
the volume of the substituent in the 3-position leads to an
increase in the stability of the catalyst.
Preparation of {1-Me2Si[3-C9H6(CH3)]2} (1): nBuLi (1.60  in hex-
ane) (38.00 mL, 60.74 mmol) was added over 15 min to a cooled
(–78 °C) solution of [Me2Si(C9H7)] (7.30 g, 25.31 mmol) in Et2O
(100 mL) in a 250-mL Schlenk tube. At the end of the addition the
solution was allowed to reach room temperature and stirred for
4 h, cooled again to –78 °C, and MeI (14.37 g, 101.24 mmol) was
added. The reaction mixture was allowed to reach room tempera-
ture and stirred for 16 h. The solvent was removed in vacuo and
hexane (100 mL) was added. Water (200 mL) was added, the or-
ganic product was extracted with hexane, the aqueous layer was
washed with hexane (3×50 mL), the organic layers combined,
dried with MgSO4, filtered and the solvent removed from the fil-
trate under reduced pressure to yield the title compound as a yellow
oil. Compound 1 was purified by column chromatography (Et2O/
1
hexane, 1:9) (yield 7.05 g, 88%). H NMR (400 MHz, CDCl3) (for
the predominant isomer): δ = 0.10 and 0.14 (2s, each 3 H, SiMe2),
0.82 (m, 6 H, CH3), 3.56 (d, J = 1.8 Hz, 2 H, 1-H), 6.82 (d, J =
1.8 Hz, 2 H, 2-H), 7.11–7.37 (m, 8 H, 4-H–7-H) ppm. MS electron
impact: m/z (%) = 316 (3) [M, {1-Me2Si[3-C9H6(CH3)]2}]+, 187
(100) [M – (3-Me – C9H6)]+, 129 (56) [M – Me2Si]+.
Preparation of {1-Me2Si(3-C9H6(CH2CH2CH3))2} (2): The synthe-
sis of 2 was carried out in an identical manner to 1. [Me2Si(C9H7)]
(7.30 g, 25.31 mmol), nBuLi (1.60  in hexane) (38.00 mL,
60.74 mmol), and BrCH2CH2CH3 (12.45 g, 101.24 mmol). Yield
8.48 g (89%). 1H NMR (400 MHz, CDCl3) (for the predominant
isomer): δ = 0.19 and 0.32 (2s, each 3 H, SiMe2), 0.95 (m, 6 H,
CH2CH2CH3), 1.39–2.73 (m, 8 H, -CH2CH2CH3), 3.50 (d, J =
1.8 Hz, 2 H, 1-H), 6.98 (d, J = 1.8 Hz, 2 H, 2-H), 7.10–7.50 (m, 8
H, 4-H–7-H) ppm. MS electron impact: m/z (%) = 372 (3) [M, {1-
Me2Si(3-C9H6(CH2CH2CH3))2}]+, 216 (100) [M – (3-Pr – C9H6)]+,
156 (23) [M – Me2Si]+.
Conclusions
We have carried out the synthesis of new examples of
ansa-bis-indenylzirconocene complexes, bearing a SiMe2
bridge, with alkyl substituents in the 3 position. The pres-
ence of these groups allows stable and very active catalysts
to be obtained in ethylene polymerization, producing poly-
ethylenes of low molecular weight, in comparison with the
unsubstituted analogue. In addition, complexes meso-[Zr{1-
Me2Si[3-η5-C9H5(CH3)]2}Cl2] and rac-[Zr{1-Me2Si[3-η5-
C9H5(CH2CH2CH3)]2}Cl2] have been characterized by X-
ray diffraction methods.
Preparation of {1-Me2Si(3-C9H6(CH2CH2CH2CH3))2} (3): The
synthesis of 3 was carried out in an identical manner to 1. [Me2-
Si(C9H7)] (7.30 g, 25.31 mmol), nBuLi (1.60  in hexane)
(38.00 mL, 60.74 mmol), and BrCH2CH2CH2CH3 (13.87 g,
101.24 mmol). Yield 9.13 g (90%). 1H NMR (400 MHz, CDCl3)
(for the predominant isomer): δ = 0.22 and 0.08 (2s, each 3 H,
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SiMe2), 0.95–2.73 (m, 18 H, -CH2CH2CH2CH3), 3.80 (d, J =
1.8 Hz, 2 H, 1-H), 6.89 (d, J = 1.8 Hz, 2 H, 2-H), 7.10–7.50 (m, 8
H, 4-H–7-H) ppm. MS electron impact: m/z (%) = 400 (3) [M, {1-
Me2Si(3-C9H6(CH2CH2CH3))2}]+, 228 (100) [M – (3-Bu-C9H6)]+,
59 (55) [M – Me2Si(C9H6)]+.
endo], 43.62 (CH3), 76.78, 86.00 (C1, C3), 118.40 (C2), 123.21 and
125.11 (C5, C6), 126.15, 126.48 (C4, C7) ppm.
rac Isomer: 1H NMR (500 MHz, CD2Cl2): δ = 1.09 [s, 6 H,
Si(CH3)2], 2.22 (s, 6 H, CH3), 5.68 (s, 2 H, 2-H), 6.97 and 7.23 (2t,
J = 8.8 Hz, each 2 H, 5-H, 6-H), 7.35 and 7.38 (2d, J = 8.8 Hz,
each 2 H, 4-H, 7-H) ppm. 13C NMR (125 MHz, CD2Cl2): δ =
–1.44 ppm [Si(CH3)2], 13.34 (CH3), 78.04, 86.40 (C1, C3), 119.32
(C2), 124.25 and 125.06 (C5, C6), 126.55 and 126.85 (C4, C7) ppm.
Preparation of {1-Me2Si(3-C9H6(CH2C6H5))2} (4): The synthesis of
4 was carried out in an identical manner to 1. [Me2Si(C9H7)]
(7.30 g, 25.31 mmol), nBuLi (1.60  in hexane) (38.00 mL,
60.74 mmol), and BrCH2C6H5 (8.66 g, 50.62 mmol). Yield 5.34 g
(45%). 1H NMR (400 MHz, CDCl3) (for the predominant isomer):
δ = 0.16 and 0.13 (2s, each 3 H, SiMe2), 2.72–3.00 (m, 4 H,
-CH2C6H5), 3.54 (d, J = 1.8 Hz, 2 H, 1-H), 6.78 (d, J = 1.8 Hz, 2 H,
2-H), 7.14–7.39 (m, 18 H, 4-H–7-H, CH2C6H5) ppm. MS electron
impact: m/z (%) = 468 (2) [M, {1-Me2Si(3-C9H6(CH2C6H5))2}]+,
264 (83) [M – (3-Bz-C9H6)]+, 91 (100) [M – Me2Si(C9H6)]+.
Both Isomers: C22H22Cl2SiZr (476.6): calcd. C 55.44, H 4.65; found
C 55.63, H 4.68.
Preparation of [Zr{1-Me2Si[3-η5-C9H5(CH2CH2CH3)]2}Cl2] (10):
The synthesis of 10 was carried out in an identical manner to 9.
Li2{1-Me2Si[3-C9H5(CH2CH2CH3)]2} (6) (4.48 g, 11.65 mmol) and
ZrCl4 (2.72 g, 11.65 mmol). Yield 1.61 g (26%). rac/meso = 38:62.
meso Isomer: 1H NMR (500 MHz, CDCl3): δ = 1.04 [s, 3 H,
Si(CH3) exo], 1.51 [s, 3 H, Si(CH3) endo], 1.07 (t, 6 H, J = 7.9 Hz,
CH2CH2CH3), 1.74 (m, 4 H, CH2CH2CH3), 2.98 (m, 4 H,
CH2CH2CH3), 5.73 (s, 2 H, 2-H), 7.07 and 7.32 (2t, J = 8.8 Hz,
each 2 H, 5-H, 6-H), 7.57 and 7.65 (2d, J = 8.8 Hz, each 2 H, 4-
H, 7-H) ppm. 13C{1H} NMR (125 MHz, CDCl3): δ = –2.45
[Si(CH3) exo], –0.71 [Si(CH3) endo], 14.46 (CH2CH2CH3), 23.62
(CH2CH2CH3), 30.78 (CH2CH2CH3), 77.30, 80.10 (C1, C3), 117.27
(C2), 124.36 and 126.04 (C5, C6), 126.30 and 126.47 (C4, C7) ppm.
Preparation of Li2{1-Me2Si(3-C9H5(CH3))2} (5): nBuLi (1.60  in
hexane) (23.79 mL, 37.92 mmol) was added dropwise over 15 min
to a cooled (–80 °C), stirred solution of {1-Me2Si(3-C9H6(CH3))2}
(1) (5.00 g, 15.80 mmol) in Et2O (80 mL) in a 250-mL Schlenk tube.
The solution was warmed up to room temperature and stirred for
4 h. An increasing turbidity developed and this finally led to the
formation of a yellow-orange suspension. The solvent was removed
in vacuo to give a yellow solid, which was washed with hexane
(2×50 mL) and dried under vacuum to yield 5 as a free flowing
yellow solid (yield 3.94 g, 76%). C22H22Li2Si (328.28): calcd. C
80.47, H 6.75; found C 80.53, H 6.80.
rac Isomer: 1H NMR (500 MHz, CDCl3): δ = 1.25 [s, 6 H,
Si(CH3)2], 1.03 (t, 6 H, J = 7.9 Hz, CH2CH2CH3), 1.65 (m, 4 H,
CH2CH2CH3), 2.84 (m, 4 H, CH2CH2CH3), 5.91 (s, 2 H, 2-H),
7.19 and 7.47 (2t, J = 8.8 Hz, each 2 H, 5-H, 6-H), 7.57 and 7.65
(2d, J = 8.8 Hz, each 2 H, 4-H, 7-H) ppm. 13C{1H} NMR
Preparation of Li2{1-Me2Si(3-C9H5(CH2CH2CH3))2} (6): The syn-
thesis of 6 was carried out in an identical manner to 5. {1-Me2Si(3-
C9H6(CH2CH2CH3))2} (2) (5.00 g, 13.28 mmol), nBuLi (1.60  in
hexane), and (19.91 ml, 31.85 mmol). Yield 4.48 g (87%).
C26H30Li2Si (384.48): calcd. C 81.22, H 7.86; found C 81.43, H
7.93.
(125 MHz, CDCl3):
δ
=
–1.12 ppm [Si(CH3)2], 14.34
(CH2CH2CH3), 23.54 (CH2CH2CH3), 30.49 (CH2CH2CH3), 77.40,
85.31 (C1, C3), 117.27 (C2), 124.55 and 124.92 (C5, C6), 126.62
and 126.72 (C4, C7) ppm.
Preparation of Li2{1-Me2Si(3-C9H5(CH2CH2CH2CH3))2} (7): The
synthesis of 7 was carried out in an identical manner to 5. {1-
Me2Si(3-C9H6(CH2CH2CH2CH3))2} (3) (5.00 g, 12.48 mmol) and
nBuLi (1.60  in hexane) (18.72 mL, 29.95 mmol). Yield (4.37 g,
85%). C28H34Li2Si (412.54): calcd. C 81.52, H 8.31; found C 81.43,
H 8.40.
Both Isomers: C26H30Cl2SiZr (532.73): calcd. C 58.62, H 5.68;
found C 58.71, H 5.69.
Preparation of [Zr{1-Me2Si[3-η5-C9H5(CH2CH2CH2CH3)]2}Cl2]
(11): The synthesis of 11 was carried out in an identical manner to
9.
Li2{1-Me2Si[3-C9H5(CH2CH2CH2CH3)]2}
(7)
(4.37 g,
10.59 mmol) and ZrCl4 (2.47 g, 10.59 mmol). Yield 2.08 g (35%).
rac/meso = 59:41.
Preparation of Li2{1-Me2Si(3-C9H5(CH2C6H5))2} (8): The synthesis
of 8 was carried out in an identical manner to 5. {1-Me2Si(3-
C9H6(CH2C6H5))2} (4) (5.00 g, 10.67 mmol) and nBuLi (1.60  in
hexane) (16.00 mL, 26.21 mmol). Yield 4.10 g (80%). C34H30Li2Si
(480.57): calcd. C 84.97, H 6.29; found C 84.83, H 6.34.
meso Isomer: 1H NMR (500 MHz, CDCl3): δ = 0.87 [s, 3 H,
Si(CH3) exo], 1.36 [s, 3 H, Si(CH3) endo], 0.89 (t, J = 7.9 Hz, 6 H,
CH2CH2CH2CH3), 1.34 (m, 4 H, CH2CH2CH2CH3), 1.51 (m, 4 H,
CH2CH2CH2CH3), 2.72 (m, 4 H, CH2CH2CH2CH3), 5.58 (s, 2 H,
2-H), 6.91 and 7.16 (2t, J = 8.8 Hz, each 2 H, 5-H, 6-H), 7.41 and
7.49 (2d, J = 8.8 Hz, each 2 H, 4-H, 7-H) ppm. 13C{1H} NMR
(125 MHz, CDCl3): δ = –2.69 [Si(CH3) exo], –0.96 [Si(CH3) endo],
13.95 (CH2CH2CH2CH3), 22.77 (CH2CH2CH2CH3), 28.24
(CH2CH2CH2CH3), 32.29 (CH2CH2CH2CH3), 77.10, 84.81 (C1,
C3), 116.88 (C2), 123.98 and 125.77 (C5, C6), 126.03, 126.19 (C4,
C7) ppm.
Preparation of [Zr{1-Me2Si(3-η5-C9H5(CH3))2}Cl2] (9): A cooled
(–78 °C) slurry of ZrCl4 (2.79 g, 12.00 mmol) in toluene (80 mL)
was rapidly added to a cooled (–78 °C) solution of Li2{1-Me2Si(3-
C9H5(CH3))2} (5) (3.94 g, 12.00 mmol) in Et2O (80 mL) in a 250-
mL Schlenk tube. The reaction mixture was stirred for 30 min at
–20 °C and then overnight at room temperature (16 h). The orange
suspension was filtered through a G4 frit with Celite. The filtrate
was evaporated to dryness under reduced pressure to yield a sticky
dark-orange product. The product was washed with Et2O (30 mL)
and the residue was dried to give an orange solid (0.86 g, 15%).
rac/meso = 55:45. For this complex, samples of the pure meso dia-
stereomer and a product enriched in the rac isomer (11.5:1) were
obtained by careful recrystallization from CH2Cl2/Et2O.
rac Isomer: 1H NMR (500 MHz, CDCl3): δ = 1.11 [s, 6 H,
Si(CH3)2], 0.90 (t, 6 H, J = 7.9 Hz CH2CH2CH2CH3), 1.34 (m, 4
H, CH2CH2CH2CH3), 1.51 (m, 4 H, CH2CH2CH2CH3), 2.82 (m,
4 H, CH2CH2CH2CH3), 5.77 (s, 2 H, 2-H), 7.06 and 7.32 (2t, J =
8.8 Hz, each 2 H, 5-H, 6-H), 7.41 and 7.49 (2d, J = 8.8 Hz, each
meso Isomer: 1H NMR (500 MHz, CD2Cl2): δ = 0.80 [s, 3 H, 2 H, 4-H, 7-H) ppm. 13C{1H} NMR (125 MHz, CDCl3): δ = –1.37
Si(CH3) exo], 1.27 [s, 3 H, Si(CH3) endo], 2.35 (s, 6 H, CH3), 5.50 [Si(CH3)2], 13.95 (CH2CH2CH2CH3), 22.77 (CH2CH2CH2CH3),
(s, 2 H, 2-H), 6.83 and 7.09 (2t, J = 8.8 Hz, each 2 H, 5-H, 6-H), 28.12 (CH2CH2CH2CH3), 32.29 (CH2CH2CH2CH3), 77.69, 85.06
7.32 and 7.44 (2d, J = 8.8 Hz, each 2 H, 4-H, 7-H) ppm. 13C{1H}
NMR (125 MHz, CD2Cl2): δ = 13.03 [Si(CH3) exo], 13.62 [Si(CH3)
(C1, C3), 117.00 (C2), 124.08 and 124.67 (C5, C6), 126.34 and
126.43 (C4, C7) ppm.
Eur. J. Inorg. Chem. 2006, 972–979
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
977

A. Otero et al.
FULL PAPER
Both Isomers: C28H34Cl2SiZr (560.79): calcd. C 59.97, H 6.11;
found C 60.21, H 6.19.
X-ray Crystal Structure Determination of meso-9 and rac-10: Inten-
sity data were collected with a Nonius-MACH3 diffractometer
equipped with a graphite monochromator and a Mo-Kα radiation
source (λ = 0.71073 Å) using a ω/2θ-scan technique. The final unit
cell parameters were determined from 25 well-centered reflections
and refined by least-squares methods. Data were corrected for Lo-
rentz and polarization effects and a semi-empirical absorption cor-
rection (Psi-scans) was made.[21]
The structures were solved using direct methods,[22] completed by
subsequent difference Fourier syntheses, and refined by full-matrix
least-squares procedures on F2.[23] All non-hydrogen atoms were
refined with anisotropic thermal parameters. The hydrogen atoms
were placed using a “riding model” and included in the refinement
at calculated positions. Weights were optimized in the final cycles.
Crystallographic data are given in Table 4.
Preparation of [Zr{1-Me2Si[3-η5-C9H5(CH2C6H5)]2}Cl2] (12): The
synthesis of 12 was carried out in an identical manner to 9. Li2{1-
Me2Si[3-C9H5(CH2C6H5)]2} (8) (4.10 g, 8.53 mmol) and ZrCl4
(2.00 g, 8.53 mmol). Yield 2.15 g (40%). rac/meso = 65:35.
meso Isomer: 1H NMR (500 MHz, CDCl3): δ = 1.01 [s, 3 H,
Si(CH3) exo], 1.29 [s, 3 H, Si(CH3) endo], δA = 4.28, δB = 4.22 (AB,
JAB = 21.6 Hz, 4 H, CH2C6H5), 5.77 (s, 2 H, 2-H), 7.02–7.48 (m, 8
H, 4-H–7-H), 7.02–7.48 (m, 10 H, CH2C6H5) ppm. 13C{1H} NMR
(125 MHz, CDCl3): δ = –1.40 [Si(CH3) exo], –0.99 [Si(CH3) endo],
34.22 (CH2C6H5), 65.84, 85.90 (C1, C3), 118.12 (C2), 124.06 and
125.85 (C5, C6), 126.12 and 126.14 (C4, C7), 118.04–140.17
(CH2C6H5) ppm.
rac Isomer: 1H NMR (500 MHz, CDCl3): δ = 0.79 [s, 6 H, Si(CH3)],
δA = 4.17, δB = 4.04 (AB, JAB = 19.6 Hz, 4 H, CH2C6H5), 5.59
(s, 2 H, 2-H), 7.02–7.48 (m, 8 H, 4-H–7-H), 7.02–7.48 (m, 10 H,
CH2C6H5) ppm. 13C{1H} NMR (125 MHz, CDCl3): δ = –2.85
[Si(CH3)2], 34.58 (CH2C6H5), 65.94, 86.32 (C1, C3), 118.04 (C2),
124.25 and 124.74 (C5, C6), 126.57 and 126.78 (C4, C7), 118.04–
140.17 (CH2C6H5) ppm.
Table 4. Crystal data and structure refinement for meso-9 and rac-
10.
meso-9
rac-10
Empirical formula
Formula weight
Temperature [K]
Wavelength [Å]
Crystal system
Space group
a [Å]
b [Å]
c [Å]
α [°]
β [°]
C22H22Cl2SiZr·CH2Cl2 C26H30Cl2SiZr·0.5C7H8
561.53
290(2)
578.78
250(2)
Both Isomers: C34H30Cl2SiZr (628.82): calcd. C 64.94, H 4.81;
found C 65.02, H 4.86.
0.71073
triclinic
¯
P1
0.71073
monoclinic
P2/c
Polymerization Experiments: Polymerizations (three runs for cata-
lyst) were carried out in a 250 mL glass reactor using toluene as a
solvent (100 mL). Catalysts (6 µmol) were treated with the appro-
priate quantity (Al/Zr = 2000) of a commercial (CROPTOM) solu-
tion of MAO in toluene (10% Al) for 15 min. Toluene (80 mL),
Al(iBu)3 scavenger (2 mL), and activated catalyst were introduced,
in this order, into the reactor and the temperature was maintained
at 343 K. The nitrogen atmosphere was removed and a continuous
flow of ethylene (1.5 bar) was introduced over 30 min. The reaction
mixture was then quenched by the addition of acidified methanol.
The polymer was collected by filtration, washed with methanol,
and dried under vacuum at room temperature for 24 h.
9.994(5)
10.430(8)
12.264(5)
86.23(4)
70.28(4)
78.74(6)
1180(1)
2
11.062(4)
12.206(4)
11.311(3)
91.59(3)
γ [°]
Volume [Å3]
Z
1526.7(8)
2
Density (calculated) [g/cm3]
Absorption coefficient [cm–1
F(000)
1.580
9.78
568
1.259
5.89
598
]
Crystal size [mm]
Index ranges
0.3×0.2×0.1
–12 Յ h Յ 13
–13 Յ k Յ 13
0 Յ l Յ 16
5894
0.4×0.3×0.2
–14 Յ h Յ 14
0 Յ k Յ 16
0 Յ l Յ 14
3858
Polymer Analysis Procedures: Mw, Mn, and Mw/Mn were mea-
sured with an Alliance GPC-2000 high temperature GPG device
from Waters Corp., Milford, MA, USA. The mobile phase was
2,4,5-trichlorobenzene (HPLC grade, J. T. Baker Ltd.) at 150 °C.
Prior to use as a mobile phase, TCB was filtered through a 0.2-µ
fiberglass filter (PALL Corp.). The GPC device was completed with
3 Styragel columns (Waters Corp.) and an additional GARD col-
umn. All columns were placed in an oven and heated to 150 °C.
The RI detector at 150 °C was used for MW determination by the
relative method. Data processing was performed using Millen-
nium ver. 4.2 Software (Waters Corp.). The sample (0.020 g) was
dissolved in 2,4,5-trichlorobenzene (10.0 mL) (HPLC grade, J. T.
Baker Ltd.) at 150 °C over 7 h. The solution was stirred four times
during this period. The hot solution (7 mL) of each sample was
placed into the metal vial equipped with a mechanism for auto-
matic filtration through 0.2-µ metal filters prior to injection. The
vials were immediately placed in an autosampler heated continually
at 150 °C. The sample was stirred for 15 min in the autosampler
prior to injection. 12 PS narrow standards in the range of MW
Reflections collected
Independent reflections
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices [I Ͼ 2σ(I)]
5638 [R(int) = 0.0497] 3674 [R(int) = 0.0168]
5638/0/266
1.056
3674/0/147
1.111
R1 = 0.0630
wR2 = 0.1479
R1 = 0.1260
wR2 = 0.1745
1.076/–1.384
R1 = 0.0466
wR2 = 0.1460
R1 = 0.0656
wR2 = 0.1567
1.218/–0.461
R indices (all data)
Largest diff. peak/hole [e·Å–3
]
2
R1 = Σ||Fo| – |Fc| |/Σ|Fo|; wR2 = Σ|[w(Fo – Fc2)2]/Σ|[w(Fo2)2]0.5
CCDC-283808 and -283809 contain the supplementary crystallo-
graphic data for this paper. These data can be obtained free of
charge from The Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data_request/cif.
from 2430 Dalton to 1.800.000 Dalton (Aldrich) were used for the Acknowledgments
calibration of the GPC device. The standards were prepared analo-
gous to the sample preparation. The concentrations of standard
solutions were calculated according the recommendations of Ald-
rich. The calibration curve is linear in all range of MW and indi-
cates the good working order of the device and especially the col-
umns.
We gratefully acknowledge financial support from the Ministerio
de Educación y Ciencia, Spain (Grant Nos. CTQ2005-07918-C02-
01/BQU and MAT2003-05345), and the Junta de Comunidades de
Castilla-La Mancha (Grant No. PBI05-029). C. A. acknowledges a
fellowship from REPSOL-YPF-UCLM (contract CTR-00-084).
978
www.eurjic.org
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2006, 972–979

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FULL PAPER
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Received: September 22, 2005
Published Online: January 19, 2006
Eur. J. Inorg. Chem. 2006, 972–979
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
979