Para-Fluoro benzyl substituted bis(indenyl) metallocenes as catalyst precursors in ethene polymerization

Article abstract of DOI:10.1016/S0022-328X(97)00625-6

The unbridged complexes bis(η⁵-(1-para-fluoro benzyl)indenyl) MCl₂ (2: M=Hf; 3: M=Zr) as well as their ethylene bridged analogues bis[(η⁵-3-(1-para-fluoro benzyl)indenyl)ethane] MCl₂ (4: M=Hf; 5: M=Zr) have been synthesized and the obtained rac- and meso-isomers were separated from the 1:1 isomer mixtures. Complexation was performed by converting the ligand precursors (1-para-fluoro benzyl)indene (1a) and bis(3-(1-para-fluoro benzyl)indenyl)ethane (1b) into their lithio salts and further treatment with MCl₄. To study the influence of the para-fluoro benzyl substituent in ethene polymerization, the catalyst precursors 2-5 were activated with methylalumoxane (MAO) and their polymerization behavior was compared to corresponding unsubstituted metallocenes. The crystal structure of meso-like 3 was determined by means of X-ray structure analysis, showing a central/lateral:gauche-type orientation of its para-fluoro benzyl substituents in the solid state.

Full text of DOI:10.1016/S0022-328X(97)00625-6

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.
Journal of Organometallic Chemistry 553 1998 173–178
ž
/
para-Fluoro benzyl substituted bis indenyl metallocenes as catalyst
precursors in ethene polymerization
)
1
Gerhard Jany , Marina Gustafsson, Timo Repo , Erkki Aitola, Jose A. Dobado,
´
2
Martti Klinga , Markku Leskela
¨
Laboratory of Inorganic Chemistry, UniÕersity of Helsinki, P.O. Box 55, FIN-00014 Helsinki, Finland
Received 26 May 1997
Abstract
5
Ž
Ž
.
.
Ž
.
The unbridged complexes bis h - 1-para-fluoro benzyl indenyl MCl2 2: MsHf; 3: MsZr as well as their ethylene bridged
5
wŽ
Ž
.
.
x
Ž
.
analogues bis h -3- 1-para-fluoro benzyl indenyl ethane MCl2 4: MsHf; 5: MsZr have been synthesized and the obtained rac-
and meso-isomers were separated from the 1:1 isomer mixtures. Complexation was performed by converting the ligand precursors
Ž
.
Ž
.
Ž
Ž
.
.
Ž
.
1-para-fluoro benzyl indene 1a and bis 3- 1-para-fluoro benzyl indenyl ethane 1b into their lithio salts and further treatment with
MCl4. To study the influence of the para-fluoro benzyl substituent in ethene polymerization, the catalyst precursors 2–5 were activated
Ž
.
with methylalumoxane MAO and their polymerization behavior was compared to corresponding unsubstituted metallocenes. The crystal
structure of meso-like 3 was determined by means of X-ray structure analysis, showing a centralrlateral:gauche-type orientation of its
para-fluoro benzyl substituents in the solid state. q 1998 Elsevier Science S.A.
Keywords: Zirconium; Hafnium; Indenyl; Polymerization; Catalysis
1. Introduction
cal calculations were carried out for a variety of poten-
tial substituents such as 2,4,6-trichloro benzyl or para-
3
Transition metal Group 4 ansa-metallocene dichlo-
rides as catalyst precursors in homogeneous olefin poly-
merization have extensively been studied, since they
opened up a path to obtain polymers with defined
microcrystalline structure by the use of a suitable ligand
environment around the catalytic active metal center
fluoro benzyl. We elected the latter one to modify the
Ž
.
mentioned bis indenyl systems and use them as catalyst
precursors in ethene polymerization.
2. Results and discussion
w
x
Ž
.
1–3 . Metallocene IV complexes are usually activated
by a cocatalyst such as MAO, forming a cationic species
which is known to be active in olefin polymerization.
Among other things, the polymerization behavior of
metallocenes is strongly depending on the nature and
position of the substituents in their ligand framework
2.1. Syntheses and calculations
A convenient route to obtain indene derivatives bear-
ing a benzyl substituent in 1-position can be performed
by reacting indenyl lithium with benzyl halides in polar
solvents. For that purpose, we treated the lithio salts of
either indene or bis 3-indenyl ethane with para-fluoro
benzyl bromide in diethyl ether, which gave the ligand
precursors 1a,b in moderate yields.
w
x
1–4 . In this context, we chose the Ind2 MCl2 and
Ž
.
EtInd2 MCl2 metallocene key structures to be altered in
1-position with a sterical demanding and electron with-
drawing group. In order to investigate the electronic
properties of the substituted indenyl fragment, theoreti-
)
Corresponding author.
3 A more detailed discussion of the performed theoretical studies
on 1-substituted indenyl ligand systems will be the subject of a future
publication.
1 Also corresponding author.
2 X-ray diffraction studies.
0022-328Xr98r$19.00 q 1998 Elsevier Science S.A. All rights reserved.

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)
174
G. Jany et al.rJournal of Organometallic Chemistry 553 1998 173–178
Theoretical calculations were performed to evaluate
rated 1:1 isomer mixtures of complexes 2–5 as catalyst
precursors for the polymerization of ethene.
4
Ž
the electronic properties of the isolated 1-para-fluoro
)
.
Ž
.
benzyl indenyl anion 1a and its parent compound,
the unsubstituted indenyl anion. Electrostatic potentials
provide information about electron-rich and electron-
poor sites inside a molecule, and electrostatic interac-
2.2. Polymerization experiments
Ž
.
The metallocene dichlorides 2–5 Fig. 1 , all carry-
ing the sterically demanding and electron withdrawing
para-fluoro benzyl group as substituent in 1-position of
their indenyl moieties, were studied in ethene poly-
merization at 508C and 2.0 bar ethene overpressure in
toluene after activation with MAO. The resulting poly-
merization data are summarized in Table 1. Further-
w
x
tions between molecules 5–9 . The numerical values
Ž
for the electrostatic potentials calculated for the centre
.
of each five- and six-membered ring of the indenyl
anion are y106 and y127 kcalrmol, whereas the
corresponding values for 1a) are significantly more
positive, y66 and y92 kcalrmol, respectively. Piccol-
rovazzi et al. were able to show that in modified
Ž
more, a series of literature known complexes Table 1,
Ž
.
Ž
.
.
bis indenyl -systems such as 4,7-F2 Ind ZrR2 the elec-
entries 6–9 was synthesized, to compare the poly-
2
tron withdrawing groups lowered both, catalytic activity
and molecular weight of the obtained polyethenes, if
merization behavior of these parental compounds to the
para-fluoro benzyl substituted indenyl complexes under
similar conditions.
The unbridged hafnium complex 6 produced when
activated with MAO high molecular weight polyethene
w
x
compared to unsubstituted Ind2 ZrCl2 10 . Hence a
decrease of the electron density in 1a) compared to its
parent compound should be in accord with a decrease of
the electron density of the respective metal complex and
thus, affect its polymerization behavior when utilized as
catalyst in ethene polymerization. To prove this sugges-
tion, the ligand precursors 1a,b were converted into
their lithio salts and reacted with HfCl4 and ZrCl4 in
dichloro methane to form the unbridged metallocene
complexes 2 and 3, as well as the ethylene bridged
ansa-metallocene complexes 4 and 5, as displayed in
Fig. 1.
Ž
.
MW s959 kgrmol with moderate activity, whereas
Ž
its zirconium analogue 7 exhibited high activity As
y1
Ž
. Ž
w
x
.
.
62500 kg PE
Zr h
, but lower MW instead
Ž
.
Table 1 . These observations are in general accordance
w
x
to studies reported earlier 12–18 . The remarkable dif-
ference in activity and MW , which is exposed by 6 and
7, diminishes if the para-fluoro benzyl group is intro-
duced to the ligand framework. The metallocene com-
plexes 2 and 3 produce only polyethene with reduced
activity and MW about 383 and 366 kgrmol, respec-
tively. Further linking of the substituted indenyl frag-
ments by an ethylene bridge in 3-position affords the
ansa-metallocene complexes 4 and 5, which polymerize
ethene with even less activity and lower MW. The
decline in activity of complex 4 is rather dramatic and
All complexes were formed as 1:1 mixtures of their
rac- and meso-isomers and could be separated by frac-
tional crystallization from hot toluene. In the case of 2
and 3, it was possible to classify the rac- and meso-like
isomers by correlating the solid state structure of meso-
like 3 vide post with the 1H NMR spectra of the
complex fractions. The ethylene bridged complexes 4
and 5 could also be separated from their rac- and
meso-mixtures but suitable crystals for X-ray structure
analysis were not obtained. The low yields in prepara-
tion of 4 and 5 also prevented further functionalization,
e.g., into their dimethyl analogues, to identify the frac-
Ž
.
its activity is even below the one found for EtFlu2 HfCl2
5
Ž
.
10 , bearing also two demanding b-substituents on
each Cp-fragment. However, the hafnocene 4 now gen-
erates polyethene with even lower MW than the zir-
conocene 5. An unusual feature, which was also re-
Ž
.
ported by Alt et al. for the bis fluorenyl complex 10
1
w
x
tions of the different structural isomers by means of H
19,20 . The general decrease in activity and MW which
w
x
NMR 11 . For this reason, we only used the unsepa-
is caused by catalyst systems 2–5 compared to 6–9, is
corresponding to polymerization results recently pub-
lished for a similar kind of substituted indenyl systems.
Ž
.
While 1-PhInd ZrCl2 still polymerized ethene with
2
4 Besides, in the case of ethene, it is less necessary to maintain a
Ž
.
certain symmetry e.g., rac or meso throughout the polymerization
Ž
process, because no stereoregular polymers can be achieved in
contrary to propylene . Exemplary, ethene was polymerized with
.
rac-like 2 under similar conditions, showing minor differences in
Ž
.
activity and MW to the 1:1 mixtures see Table 1 . Data of rac-like
w
x
2: tP s1201 s, Hf s5 mmol, yields3.59 g, activitys2152 kg
PE Hf h y1, Tm s124.68C, MW s340 kgrmol, MW rMN s3.1.
Ž
. Žw
x .
5 Polymerization data of 10 under same conditions vide supra :
Ž
.
.
Ž
.
w
x
Ž
Fig. 1. para-Fluoro benzyl substituted bis indenyl complexes 2–5
tP s4134 s, Hf s10 mmol, yields3.28 g, activitys286 kg PE
Hf h y1, Tm s124.08C, MW s305 kgrmol, MW rMN s4.3.
Žw
x
.
used as catalyst precursors for the polymerization of ethene.

(
)
G. Jany et al.rJournal of Organometallic Chemistry 553 1998 173–178
175
Table 1
Ž
.
Ethene polymerization data for catalyst systems bearing para-fluoro benzyl substituents 2–5rMAO compared to non-substituted systems
a
Ž
.
6–9rMAO under similar polymerization conditions
c
Compound
tPb
Activityd
Tme 8C
MW kgrmol
MWrMN
Ž .
s
w
M
x Ž .
mmol
Ž .
Yield g
Ž
.
Ž
.
Ž
Ž
.
Ž .
2
p-Fluoro Ind2 HfCl2
1007
1026
3621
1852
5
2
10
10
3.70
3.89
1.54
7.57
2645
6824
153
122.3
119.4
125.7
125.4
383
366
109
115
2.9
3.4
2.5
4.4
.
Ž .
3
p-Fluoro Ind2 ZrCl2
wŽ
.
x
Ž .
4
Ž .
5
Et p-Fluoro Ind2 HfCl2
Et p-Fluoro Ind2 ZrCl2
wŽ
.
x
1473
Ž .
7
Ind2 HfCl2
Ind2 ZrfCl2
rac-EtInd2 HfCl2
rac-EtInd2 ZrCl2
6
Ž .
924
1014
1354
1822
5
0.5
5
2
10.0
8.8
3.95
9.49
7812
62 500
2101
124.2
124.3
120.6
121.7
959
490
387
240
2.6
2.3
4.4
3.2
Ž .
8
Ž .
9
9377
a
w
x w x
Ethene overpressure 2.0 bar, polymerization temperature 508C and MAO excess of Al : M s5000:1.
b Polymerization time.
c MsZr, Hf.
d
y1
Ž
. Žw x .
kg PE M h
.
e
Ž
.
Onset melting temperatures of the polymers after pre-heating the samples up to 2008C and cooling down again to 708C cooling rate 108Crmin .
moderate activity, the introduction of a second phenyl
group in 3-position reduced the catalytic activity of the
unlinked metallocenes. It is most likely that a potential
electron withdrawing effect of the para-fluoro benzyl
substituent only plays a minor role in polymerization.
Our current work is focused on using the isolated,
stereorigid rac- and meso-like diastereoisomers of the
unbridged metallocenes 2 and 3 for the stereospecific
w
x
complex about 20 times 21 .
We attribute that the major reason for the observed
loss in activity and lower MW obtained with compounds
2–5 can be found in a sterical interference between the
para-fluoro benzyl substituents, the monomer and the
polymer chain. Fig. 2 illustrates how the para-fluoro
benzyl group might restrict the coordination sphere
around the catalytic active metal center, even in the
w
x
polymerization of propylene 11,22,23 .
3. Solid state structure
Table 2 summarizes the bonding parameters of
meso-like 3: Its Zr–Cl as well as the Zr–Cp distances
around the pseudotetrahedrally coordinated metal centre
Ž .
correspond to the ones reported for Ind2 ZrCl2 7 and
4
w
Ž
.
x
Ž
. w x
meso-like Cy IndH 2 ZrCl2 11 24 in the solid state.
Ž
.
Also the Cp1–Zr–Cp2 angle fs129.08 correlates
Ž
.
Ž
.
with the values found for 7 128.38 and 11 130.58 .
The distances between zirconium and the Cp-carbon
˚
˚
Ž .
Ž .
atoms of 3 range from 2.449 9 A to 2.650 9 A which
indicates no deviation from normal h5:h5 coordination
Ž
. w x
Fig. 2 25 .
The alterations from perpendicularity to the Zr–Cp
Table 2
Selected bonding parameters for meso-like 3
˚
˚
Ž .
2.417 3 A Zr–C12
Ž .
2.429 3 A
Zr–C11
Zr–Cp1
C3–C15
˚
˚
Ž .
Ž
.
2.218 11 A Zr–Cp2
2.242 11 A
˚
˚
Ž .
1.524 13 A
Ž .
1.50 2 A C15–C16
˚
˚
Ž
.
Ž .
1.53 2 A
C8–C26
C11–Zr–C12
1.492 12 A C26–C27
Ž .0
94.6 1
f, Cp1–Zr–Cp2a 129.00
C4–Cp1–Cp2–C9b 103.60
b, Cp2–Zrc 5.70
C15–Cp1–Cp2–C26b 100.60
b, Cp1–Zrc
2.30
u d
55.50
a Bending angle.
b Dihedral angle.
c Deviation from perpendicularity to the Zr–Cp vector.
dAngle between the two Cp-planes.
Fig. 2. Solid state structure of meso-like complex 3. Hydrogen atoms
are omitted for clarity.

(
)
176
G. Jany et al.rJournal of Organometallic Chemistry 553 1998 173–178
7
Ž
.
with respect to TMS. Mass spectra EI, HRMS were
acquired by JEOL JMS-SX102. Elemental analysis were
determined via Heraeus VT-CHN-Rapid. DSC measure-
ments were performed on a Perkin Elmer DSC-2, cali-
Ž
brated with indium, tin and lead temperature scanning
.
Ž
.
rate 208Crmin . Molecular weights MW and molecu-
Ž
.
lar weight distributions MWrMN of the polyethene
Ž
samples were determined by GPC Waters 150C
.
ALCrGPC in 1,2,4-trichloro benzene relative to
polystyrene standards.
4.2. Polymerizations
In a 1-l Buchi glass autoclave 300 ml of toluene and
¨
Ž
.
Ž
.
cocatalyst MAO were added, thermostated 508C ,
Ž
.
charged up with ethene overpressure 2.0 bar and
mixed with the desired amount of complex solution.
The monomer pressure "50 mbar and temperature
Fig. 3. Ligand framework of meso-like complex 3 in the solid state,
projected onto the Cl–Zr–Cl plane. Hydrogen atoms and the two
para-fluoro benzyl units are omitted for clarity.
Ž
.
Ž
.
"0.58C were kept constant during each polymeriza-
tion run. Monomer consumption, inside temperature and
pressure were controlled by real time monitoring. The
polymerizations were stopped and the polyethenes pre-
cipitated quantitatively by pouring the solution into 600
ml of methanol, acidified with aqueous hydrochloric
acid. The samples were washed several times with
methanol and dried at 708C.
vectors, b, are comparable to the ones found for 7,
whereas the angle between the two Cp-planes, u, is
reduced from 59.3 2 8 to 55.5 4 8 when indenyl is sub-
Ž .
Ž .
stituted in 1-position by para-fluoro benzyl
a
6
fragment. In the solid state of meso-like 3, the para-
fluoro benzyl substituents point towards the same direc-
tion, showing a C15–Cp1–Cp2–C26 dihedral angle of
100.68. To further correlate the structure of meso-like 3
to the one of meso-like 11, another dihedral angle
4.3. Syntheses
4.3.1. Synthesis of the ligand precursors 1a,b
Ž
.
To a solution of either 5.8 ml indene 50 mmol or
Ž
.
C4–Cp1–Cp2–C9s103.68 was chosen, displaying
Ž
.
6.45 g bis indenyl ethane 25 mmol in 200 ml Et2O,
only a minor deviation from the one reported for meso-
like 11 105.18 by Kruger et al. and the same
Ž
.
n-butyllithium 31.25 ml, 1.6 M in hexane was added
dropwise at 08C. The reaction mixture was stirred for 2
h in an ice bath and the reaction completed by the
Ž
.
¨
centralrlateral:gauche type orientation is exhibited in
w
x
Fig. 3 24,26,27 .
Ž
.
addition of 6.23 ml 50 mmol para-fluoro benzyl
bromide. After further stirring overnight at ambient
Ž
.
temperature, an aqueous solution of NH4Cl 200 ml
4. Experimental
was added and the organic layer thoroughly extracted
with Et2O. The ether was distilled off and the crude
product chromatographed on silica gel eluent: pentane
4.1. Materials
w
Ž
.
Ž
.x
1a , hexane 1b giving 1a,b as colorless sticky oils.
All preparative reactions were carried out under an
atmosphere of dry argon by using standard Schlenk
techniques. Et2O, toluene and alkanes were purified by
distillation from sodium. CH2Cl2 was distilled from
Ž
.
Ž
.
1a 5.15 g, 22.9 mmol, 45.9% : MS EI mrz: 224
q
Ž
.
Ž .
. HRMS EI Calcd for C16 H13F: 224.101. Found:
1
M
Ž
.
Ž
224.0999. H NMR 200 MHz, CDCl3 : ds2.76 dd,
.
Ž
1H, Js8.8r4.6r9.0 Hz, CH2 , 3.12 dd, 1H, Js
Ž
CaH2. Methylalumoxane MAO, 30 wt.% solution in
.
Ž
.
6.6r7.0r6.8 Hz, CH2 , 3.68–3.76 m, 1H, CHInd ,
.
toluene was purchased from Borealis Polymers Oy.
Ž
.
Ž
6.47 d, 1H, Js4.0 Hz, CHInd , 6.85 d, 1H, Js3.8
w
x
w
x
w
x
w
x
w x
Compounds 6 28 , 7 28 , 8 12 , 9 29–31 and 10 19
.
Ž
.
Hz, CHInd , 6.9–7.4 m, 8 H, aromatic H . Anal. Calcd
for C16 H13F: C, 85.68; H, 5.84. Found: C, 85.48; H,
5.77.
were prepared according to modified literature proce-
1
dures. H and 13C NMR spectra were recorded on a
Varian Gemini 2000, chemical shifts are referenced
7 Exemplary, the 13C NMR shifts for rac- and meso-like 2 are
13
Ž
.
given: C NMR 200 MHz, CDCl3 rac-like 2: d s31.97, 95.05,
113.96, 114.38, 118.08, 120.70, 122.72, 123.81, 124.50, 124.62,
124.98, 125.53, 128.97, 129.13, 134.47, 134.53, and meso-like 2:
d s32.08, 94.81, 114.04, 117.89, 119.37, 122.67, 123.35, 124.48,
124.58, 126.41, 129.10, 129.34, 134.11, 134.18.
6
w
x
The reported u value of 7 in Ref. 36 is given for the whole
indenyl moieties. If only the angle between the two Cp-planes is
Ž
.
Ž .
considered, it diminishes from 62.07 15 8 to 59.3 2 8.

(
)
G. Jany et al.rJournal of Organometallic Chemistry 553 1998 173–178
177
1
Ž
.
Ž
.
Ž
.
1b 4.91 g, 10.3 mmol, 41.4% : MS EI mrz: 474
632.0457. H NMR 200 MHz, CDCl3 : ds3.90–4.03
q
Ž
.
Ž
.
Ž
.
Ž
.
Ž
.
M
. HRMS EI Calcd for C34 H28 F2: 474.2147.
m, 4H, CH2 , 4.19 s, 4H, CH2 , 6.03 s, 2H, CHInd ,
1
Ž
.
Ž
.
.
Ž
Found: 474.2171. H NMR 200 MHz, CDCl3 : ds
6.7–7.6 m, 16 H, aromatic H , and ds3.48–3.59 m,
Ž
.
Ž
.
Ž
Ž
.
Ž
2.56–2.73 m, 2H, CH2 , 2.84 s, 4H, CH2 , 2.97–3.14
4H, CH2 , 3.70 d, 4H, Js3.8 Hz, CH2 , 5.95 s, 2H,
Ž
.
Ž
.
Ž
.
.
m, 2H, CH2 , 3.53–3.71 m, 2H, CH , 6.12 s, 2H,
CH , 6.6–7.4 m, 16 H, aromatic H . Anal. Calcd for
C34 H28 F2: C, 86.05; H, 5.94. Found: C, 86.21; H, 5.80.
CHInd , 6.7–7.6 m, 16 H, aromatic H . Anal. Calcd for
C34 H26 F2 ZrCl2: C, 64.34; H, 4.12. Found: C, 66.11; H,
4.12.
.
Ž
.
4.3.2. Synthesis of the catalyst precursors 2–5
4.4. X-ray crystallographic studies
Ž
.
2.25 g 10 mmol of the ligand precursor 1a or 2.37
Ž
.
g 5 mmol of 1b were converted into their correspond-
ing lithio salts by treatment with 6.25 ml n-butyllithium
The crystal data of meso-like 3 were collected on a
Rigaku AFC-7S single crystal diffractometer at 193 2
Ž .
Ž
.
Ž
1.6 M in hexane at 08C. After stirring for 30 min at
K using Mo–K a radiation graphite monochromatized,
.
ambient temperature the ether was distilled off and the
solid residue cooled down to y788C. A total of 200 ml
scan type wr2Q . Intensities were corrected for Lorentz
Ž
.
and polarization effects and for absorption 0.89-1.00 .
Solution: Direct methods combined with subsequent
Fourier analysis. All non-hydrogen atoms were refined
anisotropically. Hydrogen atoms were refined isotropi-
Ž
.
of pre-cooled y788C CH2Cl2 were added followed
Ž
by an addition of 5 mmol MCl4 2 and 4: MsHf; 3
.
and 5: MsZr . The suspension was stirred overnight
Ž
.
and allowed to come to room temperature. The reaction
mixture was filtered through Celite and the solvent
evaporized. The solid residue was washed with hexane
cally on calculated positions riding model . Suitable
crystals for X-ray determination were obtained by re-
crystallization from hot toluene. Crystal dimensions
Ž
.
Ž .
Ž .
and further extracted with hot toluene 100 ml . Crystal-
lization from toluene at y208C yielded to colorless 2
and 4 and lemon–yellow colored 3 and 5.
0.45=0.35= 0.20 mm; as10.332 5 , bs11.687 5 ,
3
˚
˚
Ž .
Ž .
cs21.600 6 A, asbsgs908, Vs2608 2 A ,
Ž
crystal system orthorhombic, space group P212121 No.
Ž
.
Ž
.
.
Ž
.
2 3.47 g, 4.37 mmol, 87.4% : MS EI mrz: 692–698
19 , Zs4, mol mass 608.63 grmol, D calcd s1.550
q
3
˚
Ž
.
,
with appropriate isotope ratio for C32 H24 F2 HfCl2
grcm , ls0.71073 A, data collection range us2.57
1
q
Ž
.
Ž
.
.
473 M y1a . H NMR 200 MHz, CDCl3 : d racs
to 26.498, reflections collected 2800, independent reflec-
Ž
Ž
4.14 q, 4H, Js16.2r28.2r16.0 Hz, CH2 , 5.73 d,
tions 2800, reflections refined 2778, goodness-of-fit on
2
.
Ž
Ž
2H, Js3.0 Hz, CHInd , 5.94 d, 2H, Js3.4 Hz,
F s1.050, R1s0.0605 and wR2s0.1424 2298 with
.
Ž
.
.
Ž
.
CHInd , 6.8–7.7 m, 16 H, aromatic H , and d mesos
Io )2s Io , R1s0.0776 and wR2s0.1575 all data .
The largest difference peak and hole in the final residual
electron density map situates in the vicinity of zirco-
Ž
.
Ž
4.26 d, 4H, Js9.0 Hz, CH2 , 5.19 d, 2H, Js3.2
.
Ž
.
Hz, CHInd , 6.26 d, 2H, Js3.2 Hz, CHInd , 6.8–7.7
y3
˚
Ž
.
Ž
.
m, 16 H, aromatic H . Anal. Calcd for C32 H24 F2 HfCl2:
C, 55.23; H, 3.47. Found: C, 55.43; H, 3.60.
nium 0.838 and y1.422 e A . Calculations were
carried out with the SHELXTLrPC and SHELXL-93
Ž
.
Ž
.
w
x
3 2.42 g, 3.98 mmol, 79.6% : MS EI mrz: 605–613
program systems 32,33 .
q
Ž
.
,
with appropriate isotope ratio for C32 H24 F2 ZrCl2
1
q
Ž
.
Ž
.
.
387 M y1a . H NMR 200 MHz, CDCl3 : d racs
4.5. Computational methods
Ž
Ž
4.13 q, 4H, Js16.0r23.8r16.0 Hz, CH2 , 5.87 d,
.
Ž
2H, Js3.0 Hz, CHInd , 5.99 d, 2H, Js2.6 Hz,
Semi-empirical calculations were performed using
.
Ž
.
w
x
CHInd , 6.8–7.75 m, 16 H, aromatic H , and d meso
the PM3 Hamiltonian 34,35 included in SPARTAN
Ž
.
Ž
w
x
s4.22 d, 4H, Js3.0 Hz, CH2 , 5.35 d, 2H, Js3.2
4.0 program 37 , running on a Silicon Graphics O2
workstation. All the stationary points were fully opti-
.
Ž
.
Hz, CHInd , 6.28 d, 2H, Js3.4 Hz, CHInd , 6.8–7.7
Ž
.
Ž
m, 16 H, aromatic H . Anal. Calcd for C32 H24 F2 ZrCl2:
C, 63.14; H, 3.97. Found: C, 63.66; H, 3.89.
mized without imposition of any geometrical restriction
for compound 1a) and C2v-symmetry for the indenyl
Ž
.
Ž
.
.
4 0.89 g, 1.24 mmol, 24.8% : MS EI mrz: 720–726
anion . After optimization of the structures, vibrational
1
q
Ž
.
with appropriate isotope ratio for C34 H26 F2 HfCl2 . H
analyses were carried out to check the nature of the
Ž
.
Ž
.
.
Ž
NMR 200 MHz, CDCl3 : ds3.99–4.10 m, 4H, CH2 ,
stationary points no imaginary frequencies were found
Ž
.
Ž
.
4.26 d, 4H, Js3.8 Hz, CH2 , 6.05 s, 2H, CHInd ,
indicating that the structures were true minima . Default
options were applied in the calculation of the electro-
static potentials.
Ž
.
.
Ž
6.8–7.7 m, 16 H, aromatic H , and ds3.57–3.68 m,
Ž
.
Ž
4H, CH2 , 3.77 d, 4H, Js3.8 Hz, CH2 , 5.90 s, 2H,
.
Ž
CHInd , 6.8–7.7 m, 16 H, aromatic H. Anal. Calcd for
C34 H26 F2 HfCl2: C, 56.56; H, 3.62. Found: C, 57.24;
H, 3.99.
5. Supporting information available
Ž
.
Ž
.
5 0.57 g, 0.89 mmol, 17.9% : MS EI mrz: 631–639
q
Ž
.
.
with appropriate isotope ratio for C34 H26 F2 ZrCl2
Structure determination summaries, complete tables
of atomic coordinates, bond lengths and angles,
Ž
.
HRMS EI Calcd for C34 H26 F2 ZrCl2: 632.0410. Found:

(
)
178
G. Jany et al.rJournal of Organometallic Chemistry 553 1998 173–178
w
w
x
12 J.A. Ewen, L. Haspeslagh, J.L. Atwood, H. Zhang, J. Am.
anisotropic displacement coefficients and hydrogen atom
for meso-like 3 9 pages . Ordering information is given
on any current masthead page.
Ž
.
Chem. Soc. 109 1987 6544.
Ž
.
x
13 A. Ahlers, W. Kaminsky, Makromol. Chem., Rapid Commun. 9
Ž
.
1988 457.
w
w
x
x
Ž
.
14 K. Heiland, W. Kamninsky, Makromol. Chem. 193 1992 601.
15 W. Kamninsky, R. Engehausen, K. Zoumis, W. Spaleck, J.
Ž
.
Rohrmann, Makromol. Chem. 193 1992 1643.
Acknowledgements
w
w
w
x
Ž
.
16 J. Koivumaki, Polym. Bull. 34 1995 413.
17 W. Kaminsky, Macromol. Chem. Phys. 197 1996 3907.
18 A. Fries, T. Mise, A. Matsumoto, H. Ohmori, Y. Wakatsuki,
¨
x
Ž
.
Ž
.
x
We are obliged to Arja Lehtinen GPC , Markku R.
Ž
.
Chem. Commun. 1996 783.
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Sundberg for assistance in performing theoretical cal-
w
x
19 H.G. Alt, W. Milius, S.J. Palackal, J. Organomet. Chem. 472
.
Ž
.
culations and Ulf Dietrich elementary analysis . Gen-
eral support from Borealis Polymers Oy is gratefully
acknowledged. This work has been partially funded by
the Academy of Finland, Technology Development
Centre TEKES and the Center for International Mobil-
ity CIMO . G.J. extends his thanks to N. Ogre, C. Key
and D.R. Goettel.
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.
1994 113.
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20 H.G. Alt, Russ. Chem. Bull. 44 1995 1.
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