Novel C1 symmetric zirconocenes containing substituted indenyl moieties for the stereoregular polymerization of propylene

Article abstract of DOI:10.1016/j.jorganchem.2003.08.040

The synthesis and polymerization behavior of four new asymmetric ansa -metallocenes containing a fluorenyl moiety and a substituted indenyl moiety is reported. The zirconocenes diphenylsilylene-(η ⁵-9-fluorenyl)-[η⁵-1-(3-t-butyl)indenyl]- zirconium dichloride (4), dimethylsilylene-(η⁵-9- fluorenyl)-[η⁵-1-(3-t-butyl)indenyl]-zirconium dichloride (5), ethylene-1-(η⁵-9-fluorenyl)-2-[η⁵-1- (3-t-butyl)indenyl]-zirconium dichloride (6), and diphenylsilylene- (η⁵-9-fluorenyl)-[η⁵-1-(2-methyl-4-phenyl) indenyl]-zirconium dichloride (8) were all found to be highly active for the polymerization of both ethylene and propylene when activated with excess methylaluminoxane. Compound 8 was found to produce highly isotactic polypropylene with an [mmmm] value of 83%.

Full text of DOI:10.1016/j.jorganchem.2003.08.040

Journal of Organometallic Chemistry 688 (2003) 153Á160
/
www.elsevier.com/locate/jorganchem
Novel C1 symmetric zirconocenes containing substituted indenyl
moieties for the stereoregular polymerization of propylene
John J. Esteb a, James C.W. Chien b, Marvin D. Rausch b,*
a Clowes Department of Chemistry, Butler University, Indianapolis, IN 46208, USA
b Department of Chemistry, University of Massachusetts, Amherst, MA 01003, USA
Received 8 May 2003; received in revised form 18 August 2003; accepted 18 August 2003
Abstract
The synthesis and polymerization behavior of four new asymmetric ansa-metallocenes containing a fluorenyl moiety and a
substituted indenyl moiety is reported. The zirconocenes diphenylsilylene-(h5-9-fluorenyl)-[h5-1-(3-t-butyl)indenyl]-zirconium
dichloride (4), dimethylsilylene-(h5-9-fluorenyl)-[h5-1-(3-t-butyl)indenyl]-zirconium dichloride (5), ethylene-1-(h5-9-fluorenyl)-2-
[h5-1-(3-t-butyl)indenyl]-zirconium dichloride (6), and diphenylsilylene-(h5-9-fluorenyl)-[h5-1-(2-methyl-4-phenyl)indenyl]-zirco-
nium dichloride (8) were all found to be highly active for the polymerization of both ethylene and propylene when activated with
excess methylaluminoxane. Compound 8 was found to produce highly isotactic polypropylene with an [mmmm] value of 83%.
# 2003 Elsevier B.V. All rights reserved.
Keywords: Zirconocenes; Asymmetric metallocenes; Isotactic polypropylene; Olefin polymerization
1. Introduction
The use of ZieglerÁ
production of highly isotactic polypropylene has at-
tracted a great deal of interest both academically and in
industrial settings. Chiral metallocene catalysts posses-
sing C2 symmetry have been widely studied in order to
optimize and to better understand their ability to
catalyze the stereoregular polymerization of propylene
metallocenes, C1 symmetric metallocenes possess no
direct relationship between the catalyst geometry and
the resulting polymer microstructure. C1 symmetric
catalysts have been shown to produce polyolefins with
a wide variety of microstructures ranging from atactic
[5] to syndiotactic [6] to stereoblock [7] to hemiisotactic
[8] to isotactic [9] depending on the electronic and steric
environment around the metal center.
/
Natta type metallocenes in the
For example, Razavi et al. [9a] demonstrated that by
replacing a methyl group with a tert-butyl group at the
3-position of the cyclopentadienyl moiety of the C1
[1Á3]. Spaleck et al. [4] have shown that substitution at
/
the 2- and 4-positions of the indenyl moiety are
necessary to achieve high Mw and high isotacticity in
propylene polymerizations using C2 symmetric catalysts.
To date, the best metallocene catalyst, reported by
Spaleck et al., for the production of isotactic polypro-
symmetric
isopropylidene(3-methylcyclopentadienyl)
(fluorenyl)zirconium dichloride, a highly isotactic poly-
propylene could be produced whereas the methyl sub-
stituted parent system produced hemiisotactic
polypropylene. This observation was attributed to the
fact that the larger tert-butyl group better prevented the
polymer chain from occupying one of the two coordina-
tion sites. This in turn led to stereoselective monomer
coordination at one site, and a chain stationary insertion
mechanism was proposed.
pylene is dimethylsilyleneÁ
nyl]zirconium dichloride which produces i-PP with Mw
of 920 000 Daltons and [mmmm]ꢀ99%.
Recently, research efforts have increased in the area
of C1 symmetric metallocenes. Unlike C2 symmetric
/
bis[2-methyl-4-napthylinde-
/
To date, there have been only a few reports on the use
of C1 symmetric metallocenes for the production of
isotactic polypropylene, especially when compared to
the large number of C2 symmetric species that have been
* Corresponding author. Tel.: ꢁ
4490.
/
1-413-545-6085; fax: ꢁ1-413-545-
/
E-mail address: rausch@chem.umass.edu (M.D. Rausch).
0022-328X/03/$ - see front matter # 2003 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2003.08.040

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J.J. Esteb et al. / Journal of Organometallic Chemistry 688 (2003) 153Á160
/
studied. Most of the asymmetric catalyst systems known
have been employed to produce hemiisotactic or stereo-
block polypropylenes. However in 1994, Rieger et al.
[9b] published the synthesis of several new ethylene
bridged ansa-zirconocenes containing both an indenyl
and a fluorenyl moiety. The unsubstituted derivative
ethylene-1-(9-fluorenyl)-2-(1-indenyl) zirconium dichlor-
ide was shown to produce moderate isotacticity (64%) in
propylene polymerizations. Since that time both Tho-
mas et al. [10] and Rieger et al. [11] have synthesized
several highly active catalysts of this type for the
formation of highly isotactic polypropylene by placing
substituents at key locations around the ligand frame-
work. Both Thomas and Rieger have shown the 2- and
4-positions of the indenyl moiety to be important in
producing highly isotactic polypropylene with C1 sym-
metric catalysts [10,11].
Very recently, Resconi et al. [12] synthesized methyl-
ene-bis(3-t-butyl)-1-indenyl)zirconium dichloride. The
authors were able to demonstrate that with a sufficiently
bulky group in the 3-position (such as a tert-butyl
group), one could mimic the effect of substitution at the
2- and 4-positions and therefore catalyze the polymer-
ization of propylene to highly isotactic polypropylene
2.2. Synthesis of the t-butyl indenyl containing
zirconocenes
Synthesis of zirconocenes 4Á
double deprotonation of ligands 1Á
/
6 was accomplished by
3 in Et2O with two
/
equivalents of n-BuLi to initially produce the dilithium
salts. The dilithium salts were then reacted with one
equivalent of ZrCl4 in an Et2O solution to produce the
desired zirconocenes. The silylene-bridged derivatives, 4
and 5 were incredibly sensitive to air, moisture, and
solvents. The work up had to be done very rapidly to
prevent decomposition of the complexes. Furthermore,
once 4 and 5 were isolated as solids, exposure to solvent
would result in almost immediate decomposition of the
zirconocenes. This sensitivity is not uncommon for
silylene-bridged zirconocenes containing a fluorenyl
moiety. There are several reports of similar compounds
that possess the same instability [10b,11a,13]. The
observed instability is most likely due to ring slippage
of the metalÁ
fluorenyl bond from h5 to h3 to h1 and
/
finally to complete dissociation. The ethylene-bridged
derivative 6 possessed a much greater stability than its
silylene bridged counterparts.
([mmmm]ꢀ
/
98%) of high Mw (Mwꢀ780 000 Daltons).
/
We wish to report the results of our investigation into
the effect that a (3-t-butyl)indenyl moiety in C1 sym-
metric ansa-metallocenes has on the polymerization of
propylene to isotactic polypropylene.
2. Results and discussion
2.1. Synthesis of the t-butyl indenyl containing ligands
The synthesis of the ligands was accomplished via a
relatively straightforward procedure. Initially, 3-(t-bu-
tyl)indene was deprotonated with one equivalent of n-
BuLi to produce 1-(t-butyl)indenyllithium. The lithium
salt was then reacted with chlorodiphenylsilylfluorene,
chlorodimethylsilylfluorene, or bromoethylfluorene to
2.3. Synthesis of the 2-methyl-7-phenyl indenyl
containing ligand
Reports by Razavi et al. [14] have suggested that a
one atom bridge containing two phenyl substituents is
better than a dimethylsilylene- or ethylene- bridge in
producing a high molecular weight polymer. It is
suggested that the bulk provided by the phenyl groups
helps to inhibit backbiting of the growing polymer chain
which in turn leads to greater chain lengths. In an effort
to study the effect of a diphenylsilylene-bridge on
molecular weight, we wanted to study a stable C1
symmetric zirconocene. Thomas et al. [10b] have shown
that dimethylsilylene[(2-methyl-4-phenyl)-1-indenyl]-(9-
fluorenyl)zirconium dichloride is a highly stable and
active catalyst for the production of highly isotactic
polypropylene. We therefore decided to synthesize and
produce the ligands 1Á
/
3, respectively in 50Á64% yields.
/

J.J. Esteb et al. / Journal of Organometallic Chemistry 688 (2003) 153Á
/160
155
study the diphenylsilylene derivative of the aforemen-
tioned compound.
Compound 7 was synthesized in an analogous proce-
2.5. Ethylene polymerization
All of the complexes tested were highly active in
catalyzing the polymerization of ethylene when acti-
vated with MAO (Table 1). The activities obtained
dure to the synthesis of 1Á3. Initially, 2-methyl-7-
/
phenylindene was deprotonated with one equivalent of
n-BuLi. The resulting lithium salt was reacted with
chlorodiphenylsilylfluorene to produce ligand 7 in 64%
yield.
ranged from ca. 4ꢂ
/
106 to 9ꢂ107 depending on
/
polymerization temperature and catalyst structure. The
highest activity overall was obtained with complex 8
which is also the most stable complex. In general, for all
of the species tested, the activity was lowest at 0 8C and
greatest at 20 8C. There was a slight dip in activities as
the polymerization temperature was increased further to
2.4. Synthesis of the 2-methyl-4-phenyl indenyl
containing zirconocenes
Synthesis of 8 was accomplished by the double
deprotonation of 7 with two equivalents of n-BuLi.
The dilithium salt was then reacted with one equivalent
of ZrCl4 to produce the desired metallocene. The
stability and ease of handling of 8 relative to 4 and 5
was remarkable. Compound 8 was stable in solution for
several days and could be manipulated both in and out
of solution without significant decomposition.
50 8C, which could be attributed to a more facile
decomposition of the complex at elevated temperatures.
For complexes 4Á6, the maximum molecular weights
/
were obtained at low temperatures. Molecular weights
of the polymers decreased as the polymerization tem-
perature was increased. In general, the highest molecular
weights were obtained for the silylene-bridged catalysts
4 and 5 over the ethylene-bridged catalyst 6. This
follows the general trend that is observed for most
metallocene catalysts. Also of interest is that the
diphenylsilylene-bridged catalyst 4 produced a higher
molecular weight polymer than its dimethylsilylene
bridged counterpart 5. Lastly, 8 does not follow the
molecular weight pattern observed for 4Á6. For com-
/
pound 8, maximum molecular weight is achieved at
20 8C instead of at 0 8C. This anomaly may be
attributable to incomplete activation at lower tempera-
ture for 8.
2.6. Propylene polymerization
All of the complexes tested were also highly active in
catalyzing the polymerization of propylene when acti-
vated with MAO (Table 2). The activities obtained
ranged from ca. 2ꢂ
/
105 to 1.7ꢂ107 depending on
/
polymerization temperature and catalyst structure. The

156
J.J. Esteb et al. / Journal of Organometallic Chemistry 688 (2003) 153Á160
/
Table 1
Polymerization of ethylene with zirconocene complexes activated with MAO a
Catalyst
Temperature (8C)
Yield (g) b
10ꢃ7 A c
Tm (8C)
Mw
4
4
4
5
5
5
6
6
6
8
8
8
0
20
50
0
0.369
1.319
0.869
0.459
1.399
1.159
0.819
6.739
4.819
0.999
6.969
4.189
/
0.03
0.05
0.03
0.02
0.11
0.17
0.06
0.51
0.44
0.02
0.36
0.22
0.4
1.7
1.5
0.5
1.8
2.0
0.9
8.7
8.4
1.1
9.0
7.3
132
130
130
128
127
127
130
131
130
131
129
129
666 000
649 000
477 000
590 000
524 000
218 000
350 000
327 000
298 000
462 000
586 000
174 000
/
/
/
20
50
0
/
/
/
20
50
0
/
/
/
20
50
/
/
a
Polymerization conditions: [Zr]ꢀ
/
5 mM; Al/Zrꢀ
Yields are averages of duplicate runs.
Activityꢀg of PE/(mol Zr)(conc. of monomer)(h).
/
4000:1; reaction timeꢀ5 min.
/
b
c
/
highest activity was obtained with the ethylene-bridged
catalyst 6 at 50 8C. For similar catalyst systems, it has
been demonstrated that ethylene-bridged species are
usually more active than the silylene-bridged counter-
parts. This is the trend observed for our systems as well.
The silylene-bridged species 4 and 5 were so unstable
in the presence of propylene that visible decomposition
was immediately evident at polymerization temperatures
greater than 0 8C. The pink color normally attributable
to an active cationic species turned yellow almost
immediately and no polymer was obtained. At 0 8C,
decomposition was also observed but it occurred over a
ca. 10 min time period, which allowed the catalyst to
produce some isolable polymer. The activity measure-
ments obtained for 4 and 5 are therefore in question
since the polymerization was allowed to proceed for 1 h
at which time the catalyst had presumably been inactive
for about 50 min.
indenyl moiety as has been previously demonstrated by
Thomas et al. [10b]. The activities obtained for 8 were in
the 106 range as the activity increased as the polymer-
ization temperature increased reaching a maximum
activity of 2.9ꢂ
106 at 50 8C.
/
The highest molecular weights were obtained using
catalyst 4. A diphenylsilylene bridge afforded a two-fold
increase in molecular weight over the dimethylsilylene
analog 5. A molecular weight of 104 000 Daltons was
obtained using 4, which is among the highest Mw
polypropylene produced using a C1 catalyst of this
type. Unfortunately, the instability of 4 hinders its
usefulness in an industrial setting. Catalyst 8 also
exhibited a two-fold increase in molecular weight
(40 800 Daltons) over the previously published dimethyl-
silylene[(2-Me-4-Ph)-1-indenyl]-(9-fluorenyl)zirconium
dichloride analog which gave polypropylene with mole-
cular weights of ꢀ20 000 Daltons [10b].
/
Compound 8 was stable at all polymerization tem-
peratures despite the fact that it contained a silylene
bridge. This is attributable to the added stability gained
by placing substituents at the 2- and 4-positions of the
The isotacticity of the polypropylenes produced was
moderate. There was an increase in stereoregularity
using 4Á
/
6 reaching a maximum of 82% versus the
unsubstituted ethylene-1-(9-fluorenyl)-2-(1-indenyl) zir-
Table 2
Polymerization of propylene with zirconocene complexes activated with MAO a
Catalyst
Temperature (8C)
Yield (g) b
10ꢃ6 A c
Mw
[mmmm] (%)
4
5
6
6
6
8
8
8
0
0
0.259
0.179
1.359
4.249
6.649
0.459
0.839
0.429
/
0.02
0.02
0.07
0.25
0.32
0.04
0.05
0.03
0.22
0.15
1.2
104 000
56 300
72
69
82
79
75
80
83
83
/
0
/
n.d.
20
50
0
/
5.1
24 700
6600
/
17.0
0.4
/
45 000
40 800
6800
20
70
/
1.0
2.9
/
a
Polymerization conditions: [Zr]ꢀ
/
25 mM; Al/Zrꢀ
Yields are averages of duplicate runs.
Activityꢀg of PP/(mol of Zr)(conc. of monomer)(h).
/
4000:1; reaction timeꢀ
/1 h.
b
c
/

J.J. Esteb et al. / Journal of Organometallic Chemistry 688 (2003) 153Á
/160
157
conium dichloride, which exhibited an mmmm pentad of
64% [8b]. For 4 and 5 the mmmm pentad was 72 and
69%, respectively. Although these values are respectable,
producing a yellow suspension, which was hydrolyzed
with a saturated NH4Br (aq.) solution. The mixture was
separated and the aqueous layer was extracted with 2ꢂ
/
they do not approach the 95Á
/
98% obtained by Resconi
25 ml of CH2Cl2. The organic layers were combined,
dried over anhydr. MgSO4, filtered, and the solvent
removed yielding a yellow oil. The oil was dissolved in a
with his bis-[3(-t-butyl)indenyl]zirconium dichloride
catalysts [12]. The best overall stereoregularity was
obtained with the ethylene-bridged species 6. The
maximum isotacticity was obtained at 0 8C. The stereo-
regularity steadily decreased to 79% at 20 8C and finally
to 75% at 50 8C. Both Rieger et al. [9b,11] and Thomas
et al. [10] have observed the general trend of decreased
stereoregularity at elevated temperatures in similar
ethylene-bridged systems.
minimal amount of pentane and cooled to ꢃ20 8C to
/
produce a white precipitate. Recrystallization from
toluene gave 1.17 g (64.4%) of 1 as white crystals, m.p.
206Á
/
207 8C. Anal. Found: C, 87.80; H, 6.74 C38H34Si.
1
Anal. Calc.: C, 87.98; H, 6.61%. H-NMR (CDCl3): d
7.71Á
6.80 (m, 26H, aromatic H); 6.39 (d, 1H, sp2-H);
/
4.80 (s, 1H, Flu-C5-sp3); 4.41 (d, 1H, Ind-C5-sp3); 1.10
(s, 9H, C(CH3)3).
3. Experimental
3.2. (9-Fluorenyl)-1-[(3-t-butyl)indenyl]dimethylsilane
(2)
All reactions were carried out under an inert Ar
atmosphere using standard Schlenk techniques. The Ar
was purified by drying with phosphorus pentoxide,
calcium chloride and molecular sieves, and deoxyge-
nated with BTS catalyst. Toluene, hexane, Et2O, and
pentane were distilled from Na/K alloy under Ar.
Methylene chloride was distilled under Ar from CaH2.
Tetrahydrofuran (THF) was dried initially over sodium
wire, distilled from sodium/benzophenone under Ar,
and finally distilled from Na/K alloy under Ar.
To an Ar purged Schlenk tube equipped with a
magnetic stir bar was added 1.20 g (7.05 mmol) of 3-
(t-butyl)indene. The solid was dissolved in 50 ml of dry
Et2O and the solution was cooled to 0 8C. A 1.6 M
solution of n-BuLi in hexane (4.4 ml, 7.05 mmol) was
added dropwise via syringe producing a yellow solution.
The solution was allowed to warm to r.t. and was stirred
for 4 h. Next, 1.83 g (7.05 mmol) of chlorodimethylsilyl-
fluorene were dissolved in 25 ml of dry Et2O and
transferred slowly to the indenyl lithium solution via
cannula. The resulting solution was stirred overnight
producing a yellow suspension, which was hydrolyzed
with a saturated NH4Br (aq.) solution. The mixture was
Methylaluminoxane was purchased from Akzo No-
bel. Celite was purchased from Fisher Scientific. Chlor-
odiphenylsilylfluorene [15], chlorodimethylsilylfluorene
[15], bromoethylfluorene [10a], 3-(t-butylindene) [12],
and 2-methyl-7-phenylindene [3a] were synthesized by
literature procedures. All other reagents were purchased
from Aldrich and were used without further purifica-
separated and the aqueous layer was extracted with 2ꢂ
/
25 ml of CH2Cl2. The organic layers were combined,
dried over anhydr. MgSO4, filtered, and the solvent
removed yielding a yellow oil. The oil was dissolved in a
1
tion. H-NMR spectra were recorded on a Varian XL-
200 spectrometer using Me4Si as an internal standard.
Mass spectrometry was performed by the Mass Spectro-
metry Center, University of Massachusetts, Amherst.
Microanalyses were performed by the Microanalytical
Laboratory, University of Massachusetts, Amherst,
MA.
minimal amount of pentane and cooled to ꢃ20 8C to
produce a white precipitate. Recrystallization from
hexane gave 1.51 g (55%) of 2 as white crystals, m.p.
/
123Á
Anal. Calc.: C, 85.22; H, 7.66%. H-NMR (CDCl3): d
7.93 (d, 2H, aromatic H); 7.66Á7.02 (m, 10H, aromatic
H); 5.84 (d, 1H, sp2-H); 4.08 (s, 1H, Flu-C5-sp3); 3.37 (d,
1H, Ind-C5-sp3); 1.31 (s, 9H, C(CH3)3); ꢃ
0.14 (s, 3H,
CH3SiCH3); ꢃ0.51 (s, 3H, CH3SiCH3).
/
124 8C. Anal. Found: C, 85.49; H, 7.56 C28H30Si.
1
/
3.1. (9-Fluorenyl)-1-[(3-t-butyl)indenyl]diphenylsilane
/
(1)
/
To an Ar purged Schlenk tube equipped with a
magnetic stir bar was added 0.60 g (3.52 mmol) of 3-
(t-butyl)indene. The solid was dissolved in 25 ml of dry
Et2O and the solution was cooled to 0 8C. A 1.6 M
solution of n-BuLi in hexane (2.2 ml, 3.52 mmol) was
added dropwise via syringe producing a yellow solution.
The solution was allowed to warm to r.t. and was stirred
for 4 h. Next, 1.35 g (3.52 mmol) of chlorodiphenylsilyl-
fluorene were dissolved in 20 ml of dry Et2O and
transferred slowly to the indenyl lithium solution via
cannula. The resulting solution was stirred overnight
3.3. 1-(9-Fluorenyl)-2-[(3-t-butyl)indenyl]ethane (3)
To an Ar purged Schlenk tube equipped with a
magnetic stir bar was added 1.87 g (11.0 mmol) of 3-
(t-butyl)indene. The solid was dissolved in 80 ml of dry
THF and the solution was cooled to 0 8C. A 1.6 M
solution of n-BuLi in hexane (6.9 ml, 11.0 mmol) was
added dropwise via syringe producing an orange solu-
tion. The solution was allowed to warm to r.t. and was
stirred for 4 h. Next, 3.0 g (11.0 mmol) of bromoethyl-
fluorene were added as a solid. The resulting solution

158
J.J. Esteb et al. / Journal of Organometallic Chemistry 688 (2003) 153Á160
/
was stirred overnight and was hydrolyzed with a
saturated NH4Br (aq.) solution. The mixture was
separated and the aqueous layer was extracted with
solution with a white suspension. Filtration of the
suspension followed by concentration of the solution
to 5 ml and cooling to ꢃ20 8C produced an orange
/
2ꢂ
/
25 ml of Et2O. The organic layers were combined,
solid. The solid was filtered and dried in vacuo to give
0.399 g (22.8%) of 5. MS (EI) Calc. for C28H28Cl2SiZr:
dried over anhydr. MgSO4, filtered, and the solvent
removed yielding a yellow oil. The oil was dissolved in a
1
554; Found: 554. H-NMR (CDCl3): d 8.01Á
/
6.82 (m,
minimal amount of EtOH and cooled to ꢃ
/
20 8C to
12H, aromatic H); 5.72 (s, 1H, Ind-C5); 1.50 (s, 3H,
CH3SiCH3); 1.36 (s, 9H, C(CH3)3); 1.24 (s, 3H,
CH3SiCH3).
produce 2.0 g (50%) of 3 as a yellow precipitate which
melted upon warming to r.t. Anal. Found: C, 92.24; H,
1
7.58 C28H28. Anal. Calc.: C, 92.26; H, 7.74%. H-NMR
(CDCl3): d 7.85 (d, 2H, aromatic H); 7.54Á
10H, aromatic H); 6.06 (d, 1H, sp2-H); 3.96 (t, 1H, Flu-
C5-sp3); 3.24 (m, 1H, Ind-C5-sp3); 2.42Á
1.55 (m, 4H,
CH2CH2 bridge); 1.33 (s, 9H, C(CH3)3).
/
7.03 (m,
3.6. Ethylene-1-(h5-9-fluorenyl)-2-[h5-1-(3-t-
butyl)indenyl]-zirconium dichloride (6)
/
To an Ar purged Schlenk tube equipped with a
magnetic stir bar was added 0.509 g (1.4 mmol) of 3.
The solid was dissolved in 20 ml of dry Et2O and the
solution was cooled to 0 8C. A 1.6 M solution of n-BuLi
in hexane (1.75 ml, 2.8 mmol) was added dropwise via
3.4. Diphenylsilylene-(h5-9-fluorenyl)-[h5-1-(3-t-
butyl)indenyl]-zirconium dichloride (4)
To an Ar purged Schlenk tube equipped with a
magnetic stir bar was added 0.237 g (0.46 mmol) of 1.
The solid was dissolved in 20 ml of dry Et2O and the
solution was cooled to 0 8C. A 1.6 M solution of n-BuLi
in hexane (0.571 ml, 0.92 mmol) was added dropwise via
syringe producing a yellowÁorange solution. The solu-
/
tion was allowed to warm to r.t. and was stirred for 8 h.
The solution was cooled again to 0 8C and 0.326 g (1.4
mmol) of ZrCl4 was added directly to the dianion
solution as a solid. The resulting suspension was stirred
syringe producing a yellowÁ
/
orange solution. The solu-
overnight at r.t. yielding a bright redÁorange precipi-
/
tion was allowed to warm to r.t. and was stirred for 8 h.
The solution was cooled again to 0 8C and 0.106 g (0.46
mmol) of ZrCl4 was added directly to the dianion
solution as a solid. The resulting suspension was stirred
tate. Filtration of the Et2O solution followed by
extraction of the residue in CH2Cl2 produced a red
solution with a white suspension. Filtration of the
suspension followed by concentration of the solution
overnight at r.t. yielding a bright redÁ/orange precipi-
to 5 ml and cooling to ꢃ20 8C produced an orange
/
tate. Filtration of the Et2O solution followed by
extraction of the residue in CH2Cl2 produced a red
solution with a white suspension. Filtration of the
suspension followed by concentration of the solution
solid. The solid was filtered and dried in vacuo to give
0.114 g (15.6%) of 6. Anal. Found: C, 62.21; H, 5.23.
Anal. Calc.: C, 64.10; H, 5.00%. MS (EI) Calc. for
C28H26Cl2Zr: 524; Found: 524. 1H-NMR (CDCl3): d
to 5 ml and cooling to ꢃ
/
20 8C produced an orange
7.95Á/7.03 (m, 12H, aromatic H); 6.36 (s, 1H, Ind-C5);
solid. The solid was filtered and dried in vacuo to give
0.083 g (26.8%) of 4. MS (EI) Calc. for C38H32Cl2SiZr:
4.66Á
/
3.82 (m, 4H, bridge); 1.27 (s, 9H, C(CH3)3).
1
677; Found: 677. H-NMR (CDCl3): d 7.78Á
/6.82 (m,
3.7. (9-Fluorenyl)-1-[(2-methyl-4-
phenyl)indenyl]diphenylsilane (7)
22H, aromatic H); 6.31 (s, 1H, Ind-C5); 1.17 (s, 9H,
C(CH3)3).
To an Ar purged Schlenk tube equipped with a
magnetic stir bar was added 1.0 g (4.85 mmol) of 2-
methyl-7-phenyl indene. The solid was dissolved in 50
ml of dry Et2O and the solution was cooled to 0 8C. A
1.6 M solution of n-BuLi in hexane (3.0 ml, 4.85 mmol)
was added dropwise via syringe producing a yellow
solution. The solution was allowed to warm to r.t. and
was stirred for 4 h. Next, 1.89 g (4.85 mmol) of
chlorodiphenylsilylfluorene was dissolved in 25 ml of
dry Et2O and transferred slowly to the indenyl lithium
solution via cannula. The resulting solution was stirred
overnight producing a yellow suspension, which was
hydrolyzed with a saturated NH4Br (aq.) solution. The
mixture was separated and the aqueous layer was
3.5. Dimethylsilylene-(h5-9-fluorenyl)-[h5-1-(3-t-
butyl)indenyl]-zirconium dichloride (5)
To an Ar purged Schlenk tube equipped with a
magnetic stir bar was added 1.24 g (3.16 mmol) of 2.
The solid was dissolved in 50 ml of dry Et2O and the
solution was cooled to 0 8C. A 1.6 M solution of n-BuLi
in hexane (3.95 ml, 6.32 mmol) was added dropwise via
syringe producing a yellowÁorange solution. The solu-
/
tion was allowed to warm to r.t. and was stirred for 8 h.
The solution was cooled again to 0 8C and 0.736 g (3.16
mmol) of ZrCl4 was added directly to the dianion
solution as a solid. The resulting suspension was stirred
overnight at r.t. yielding a bright redÁ/orange precipi-
extracted with 2ꢂ25 ml of CH2Cl2. The organic layers
/
tate. Filtration of the Et2O solution followed by
extraction of the residue in CH2Cl2 produced a red
were combined, dried over anhydr. MgSO4, filtered, and
the solvent removed yielding a yellow oil. The oil was

J.J. Esteb et al. / Journal of Organometallic Chemistry 688 (2003) 153Á
/160
159
dissolved in a minimal amount of pentane and cooled to
20 8C to produce a white precipitate. Recrystalliza-
tion from toluene gave 1.70 g (64%) of 7 as white
500 spectrometer. Molecular weights were determined
by high temperature GPC in 1,2,4-trichlorobenzene at
135 8C.
ꢃ
/
crystals, m.p. 193Á195 8C. Anal. Found: C, 89.39; H,
/
5.88 C41H32Si. Anal. Calc.: C, 89.08; H, 5.84%. 1H-
NMR (CDCl3): d 8.05 (d, 1H, aromatic H); 7.83 (t, 1H,
Acknowledgements
aromatic H); 7.55Á6.71 (m, 24H, aromatic H); 6.29 (s,
/
1H, sp2-H); 4.98 (s, 1H, Flu-C5-sp3); 4.55 (s, 1H, Ind-
C5-sp3); 1.99 (s, 3H, CH3).
We would like to thank Dr. G. Dabkowski for
microanalyses and Dr. L.C. Dickinson for assistance
with 13C-NMR. Mass spectral data were obtained at the
University of Massachusetts Mass Spectrometry Facil-
ity, which is supported, in part, by the National Science
Foundation. We would also like to thank SOLVAY
Polyolefins Europe-Belgium for their financial support
of this research program.
3.8. Diphenylsilylene-(h5-9-fluorenyl)-[h5-1-(2-methyl-
4-phenyl)indenyl]-zirconium dichloride (8)
To an Ar purged Schlenk tube equipped with a
magnetic stir bar was added 0.400 g (0.73 mmol) of 7.
The solid was dissolved in 20 ml of dry Et2O and the
solution was cooled to 0 8C. A 1.6 M solution of n-BuLi
in hexane (0.91 ml, 1.45 mmol) was added dropwise via
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The solution was cooled again to 0 8C and 0.169 g (0.73
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solution as a solid. The resulting suspension was stirred
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J.J. Esteb et al. / Journal of Organometallic Chemistry 688 (2003) 153Á160
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