Steric and electronic effects of R in (2-(4-R-C6H4)indenyl)2ZrCl2catalysts on the synthesis of elastomeric polypropylene

Article abstract of DOI:10.1016/S1381-1169(98)00006-5

Metallocene catalysts derived from bis(2-arylindenyl)zirconium dichloride catalysts yield elastomeric stereoblock polypropylene. A study of the steric and electronic effects of varying the 4-substituent of bis(2-(4-R-C₆ H₄)indenyl)zirconium dichloride [(1 R=H, 2 R=Me, 3 R=Et, 4 R=nBu, 5 R=tBu, 6 R=SiMe₃, 7 R=CF₃, 8 R=Cl)] on propylene polymerization at 25, 50, 75 psig and bulk propylene revealed that the polymerization behavior of these catalysts is not strongly influenced by the nature of the substituent in the 4-position of the 2-aryl substituent. Examinations of the microstructure of the elastomeric polypropylenes produced showed that for catalysts 2-8 the isotacticities varied over a small range and were similar to those produced by catalyst 1 (20% ≤ [mmmm] ≤ 44%). The catalyst productivities and molecular weights also showed the same trend. Complex 3 was crystallographically characterized and was found to crystallize in exclusively the meso conformation.

Full text of DOI:10.1016/S1381-1169(98)00006-5

Ž
.
Journal of Molecular Catalysis A: Chemical 136 1998 23–33
Steric and electronic effects of R in
ž ž
/
/
2- 4-R-C6 H4 indenyl 2 ZrCl2catalysts on the synthesis of
elastomeric polypropylene
a
a
a
a,)
Shirley Lin , Elisabeth Hauptman , Tapan K. Lal , Robert M. Waymouth
,
b
b
Roger W. Quan , Andreas B. Ernst
Department of Chemistry, Stanford UniÕersity, Stanford, CA 94305, USA
a
b
Amoco Chemicals DeÕelopment and DiÕersification, 150 West WarrenÕille Road, PO Box 3011, NaperÕille, IL 60566-7011, USA
Received 3 December 1997; accepted 23 December 1997
Abstract
Metallocene catalysts derived from bis 2-arylindenyl zirconium dichloride catalysts yield elastomeric stereoblock
Ž
.
Ž
Ž
.
.
polypropylene. A study of the steric and electronic effects of varying the 4-substituent of bis 2- 4-R-C6H4 indenyl zirconium
wŽ
.x
dichloride 1 R5H, 2 R5Me, 3 R5Et, 4 R5nBu, 5 R5tBu, 6 R5SiMe3, 7 R5CF3, 8 R5Cl on propylene
polymerization at 25, 50, 75 psig and bulk propylene revealed that the polymerization behavior of these catalysts is not
strongly influenced by the nature of the substituent in the 4-position of the 2-aryl substituent. Examinations of the
microstructure of the elastomeric polypropylenes produced showed that for catalysts 2–8 the isotacticities varied over a
Ž
w
x
.
small range and were similar to those produced by catalyst 1 20%F mmmm F44% . The catalyst productivities and
molecular weights also showed the same trend. Complex 3 was crystallographically characterized and was found to
crystallize in exclusively the meso conformation. q 1998 Elsevier Science B.V. All rights reserved.
Keywords: Elastomeric polypropylene; Metallocene; Electronic effects
1. Introduction
monomer insertion, but faster than the rate of
Ž
.
synthesis of a single polymer chain Fig. 1 . The
microstructure of polymers produced by these
catalysts is sensitive to experimental conditions
and to the ligand structure around the metal
Ž
Metallocene catalysts derived from bis 2-
w x
.
phenylindenyl zirconium dichloride catalysts 1
w
yield elastomeric stereoblock polypropylene 2–
x
w
x
10 . The proposed mechanism for stereoblock
1,11 . Specifically, variation of substituents at
Ž Ž
the 3,5-positions of the phenyl ring in 2- 3,5-
polymer formation involves interconversion be-
tween an aspecific and an isospecific state of
the catalysts at a rate slower than the rate of
.
.
R2-C6H3 indenyl ZrCl2 has been shown to
2
Ž
w
x.
have dramatic effects on the tacticity mmmm
of the polymers, as measured by 13C NMR: for
Ž
Ž
.
.
w
x
2- 3,5-R2-C6H3 indenyl ZrCl2 mmmm s
2 w
x
)
24% for R5CH3, whereas mmmm s73% for
Corresponding author.
1381-1169r98r$ - see front matter q 1998 Elsevier Science B.V. All rights reserved.
Ž
.
PII: S1381-1169 98 00006-5

(
)
24
S. Lin et al.rJournal of Molecular Catalysis A: Chemical 136 1998 23–33
Fig. 1. Proposed mechanism for formation of stereoblock
polypropylene.
Ž .
Fig. 3. ORTEP diagram and selected bond distances 8 and bond
Ž . Ž . Ž . Ž . Ž . Ž .
R5CF3. In this report, we report investigations
of the effects of substituents at the 4-position in
angles
8
for 3. Zr–C 1 2.475 2 , Zr–C 2 2.567 2 , Zr–C 3
Ž . Ž . Ž . Ž . Ž .
Ž .
Ž
.
2.527 2 , Zr–C 4 2.603 2 , Zr–C 9 2.550 2 , Zr–C 18 2.551 2 ,
Ž . Ž . Ž .
Ž
.
Ž
.
Ž .
Zr–C 19 2.508 2 , Zr–C 20 2.473 2 , Zr–C 21 2.94 2 , Zr–
Ž . Ž . Ž . Ž . Ž . Ž . Ž . Ž .
Ž
Ž
.
.
2- 4-R-C6H4 indenyl ZrCl2rMAO catalysts.
2
Ž
.
C 26 2.647 2 , Cl 1 –Zr 1 –Cl 2 97.55 2 , C 1 –C 2 –C 3
The family of catalysts studied is shown in Fig.
Ž .
Ž
.
Ž
.
Ž
.
Ž .
107.3 2 , C 18 –C 19 –C 20 108.3 2 .
2.
1. The dihedral angle between the planes de-
fined by the indenyl ligands and the aryl rings is
2. Results
Ž
.
larger 15.38 and 15.68 for 3 than that observed
for 1 or the two 3,5-aryl substituted catalysts
Catalysts 2–7 were synthesized in a manner
analogous to 1 in low to moderate yields
Ž
.
w
x
F108 1,11 .
w
x
1,11,12 . Crystallization of catalyst 3 from
The results of solution polymerizations at 25,
toluenerpentane at 188C afforded crystals suit-
able for X-ray analysis. The molecular structure
and selected bond distances and angles for 3 are
given in Fig. 3. The structure of 3 resembles
that of the meso rotamer previously reported for
50, 75 psig propylene and liquid propylene
bulk for catalysts 1–8 activated with methyla-
Ž
.
Ž
.
luminoxane MAO are summarized in Table 1.
All polymerizations were conducted with the
same batch of MAO to minimize differences in
productivity, as well as fluctuations in molecu-
lar weight and tacticity of the polymers pro-
duced. Entries 20–22 are duplicate runs of cata-
lyst 5 in liquid propylene to insure reproducibil-
ity of the experiment.
As expected, productivity increased with
Ž
.
propylene pressure monomer concentration for
w
x
the catalyst series 13 . This trend has also been
observed for other propylene polymerization
catalysts. From Table 1, it is apparent that all
productivities are of the same magnitude for
each catalyst at similar monomer pressures.
The data in Table 1 also show an increase in
molecular weight with propylene pressure as
expected; Mw for a polymer made at a given
pressure is similar for catalysts 1–8. Polydis-
persities are higher than what is predicted
for homogeneous Ziegler–Natta catalysts
Ž
.
.
Fig. 2. Variation of substituents for 2-4-R-C6 H4 indenyl 2 ZrCl2
catalysts.

(
)
S. Lin et al.rJournal of Molecular Catalysis A: Chemical 136 1998 23–33
25
Table 1
Propylene polymerizations using catalysts 1–8 and MAO
a
c
Productivity kgPPrmol Zrrh Mwb kgrmol MwrMn m % mmmm %
Ž . Ž . w x w x
Ž
Ž
.
.
Ž
.
Entry Catalyst 2- 4-R PhInd 2 ZrCl2 Pressure psig
1
2
3
4
1
25
50
75
Bulk
863
1780
2679
2710
220
303
386
496
3.66
4.34
4.93
5.01
66
71
70
70
27
33
33
33
Ž
.
R5H
5
6
7
8
2
25
50
75
Bulk
842
1290
1474
2001
163
311
410
510
3.29
3.76
3.81
5.76
69
72
73
73
32
39
41
42
Ž
.
R5CH3
9
3
25
50
75
bulk
780
1544
2364
2390
211
343
406
505
3.58
4.15
5.10
4.42
69
73
72
74
31
37
38
39
Ž
.
10
11
12
R5Et
13
14
15
16
4
25
50
75
Bulk
697
1289
2322
2440
217
351
408
506
3.49
4.16
5.64
5.41
67
71
73
72
29
37
40
37
Ž
.
R5nBu
17
18
19
20
21
22
5
25
50
75
Bulk
Bulk
Bulk
578
1174
2019
2698
2356
2314
219
357
381
439
388
444
3.23
3.66
4.84
4.64
4.77
4.08
67
71
73
71
71
68
29
34
40
33
32
28
Ž
.
R5tBu
23
24
25
26
6
25
50
75
Bulk
786
1344
2269
2510
173
317
413
480
2.97
3.67
4.39
3.83
68
70
71
74
29
33
37
39
Ž
.
R5TMS
27
28
29
30
7
25
50
75
Bulk
775
1281
1704
2631
138
190
470
457
2.84
3.21
5.30
4.71
62
66
69
69
21
26
33
30
Ž
.
R5CF3
31
32
33
34
8
25
50
75
Bulk
331
689
1141
3333
102
149
328
490
3.60
4.00
4.70
4.00
60
66
67
76
20
27
27
44
Ž
.
R5Cl
aw
x
w x w x Ž .
M, Al r Zr s1000; 100 ml toluene total volume, 1 h, 208C solution runs ; 80 ml liquid propylene, 20 ml toluene,
y5
Zr s5=10
Ž
.
20–40 min, 208C bulk runs .
b Determined by high-temperature GPC vs. polypropylene standards.
13
c Pentad distribution determined from C NMR 300 MHz, tetrachloroethane, 1008C .
Ž
.
Ž
. w x
MwrMn f2.0 13 and follow no observable
We observed an increase in isotactic pentads,
w
x
trend with pressure.
mmmm , in solution polymerizations with in-
Ž
.
The microstructure of the polypropylenes
creasing monomer concentration pressure
which has been seen previously with this type
13
1
w
x
produced was determined by C NMR 13 .
2
w
x
of catalyst 1,12 . For a given catalyst, the
1 Pentad percentages have measured errors of approximately
"2%.
2 E. Hauptman, R.M. Waymouth, unpublished results.

(
)
26
S. Lin et al.rJournal of Molecular Catalysis A: Chemical 136 1998 23–33
isotacticity of polymers produced in bulk poly-
merizations was usually similar to that of the 75
psig solution polymerizations, the only excep-
tion being catalyst 8.
ring have little effect on productivities and
molecular weights for catalysts 1–8. For exam-
ple, comparable amounts of polymer are pro-
duced by catalysts 5 and 8, which have the most
Comparisons of polymer isotacticities for a
given pressure revealed that the polymerization
behavior of these catalysts is not strongly influ-
enced by the nature of the substituent in the
4-position of the 2-aryl substituent. Catalysts
derived from metallocenes 1–6 all yield poly-
mers of similar tacticity, molecular weight and
molecular weight distribution. Catalysts derived
from the trifluoromethyl and chloro-substituted
complexes 7 and 8 yield polymers with lower
isotacticities than catalysts 1–6, especially at
lower pressures. Although catalyst 8 produced
and least electron-donating substituents, respec-
3
w
x
tively
16,17 . Catalysts 1–8 also produced
polymers of similar molecular weights. For
bridged catalysts, a slight enhancement in Mw
is observed with increasing steric size and elec-
tron-donating capability of the substituent on
the ligand; this effect has been interpreted to be
due to the increased electron density at the
metal, which discourages conformations that
w
x
lead to b-H elimination 14,15 . Our results
show no such trend.
The nature of the substituent in the 4-position
appears to have little effect on polymer mi-
crostructure. Catalysts 1–8 differ little in
w
x
polymers with the highest mmmm content out
of all the catalysts studied in liquid propylene,
in the solution polymerizations it yielded poly-
mers of lower isotacticity than catalysts 1–6.
w
x
mmmm over the four monomer concentrations
despite the large differences in the steric and
electronic demands of the R-substituent. This
suggests either that the 4-substituent is not cor-
rectly positioned to influence monomer inser-
tion, or that the changes in steric bulk of the
substituents is not sufficient to affect the rate of
interconversion or the equilibrium between rac
and meso rotamers.
3. Discussion
The activities and stereospecificity of metal-
locene catalysts depend on steric and electronic
environment provided by the cyclopentadienyl
w
x
ligands 13–15 . In the bridged zirconocene sys-
tems electronic effects have been probed by
introducing substituents on the indenyl rings
sufficiently far away from the catalyst active
site such that their steric influence could largely
be discounted. For the unbridged catalysts, it is
more difficult to divorce steric factors from
electronic factors. The substituent R could influ-
ence not only monomer coordination and the
conformation of the growing polymer chain, but
also the rate of rotation of the indenyl rings and
the equilibrium constant between the rac-like
and meso-like rotamers. Electronic and steric
changes might also affect ion-pairing between
the active metal cation and the co-catalyst an-
ion, which may influence ligand rotation and
chain propagation rates.
Electronic effects are likewise difficult to
interpret in these unbridged systems, in that we
observe opposite trends for trifluoromethyl sub-
stituted 2-arylindene catalysts depending on
whether the trifluoromethyl substituent is substi-
tuted in the 3,5- or 4-position of the 2-aryl ring:
Ž
Ž
.
.
catalysts derived from 2- 3,5- CF3 2-C6H3 in-
.
denyl ZrCl2 yield polypropylenes with tactici-
ties as high as mmmm s74% 11 , whereas
catalysts derived from 2- 4-CF3C 6 H 4
2
w
x
w x
Ž
.
x
.
w
indenyl ZrCl2 7 yield polymers with mmmm
2
F33%.
3 Some indication of the variation in steric and electronic
properties in the 4-substituent can be taken from Es, the steric Taft
Ž
.
Ž
parameter, which changes from 1.24 for R5H to y1.54 for
The data in Table 1 show that steric and
electronic effects at the 4-position of the aryl
.
R5tBu , and s p, the para Hammett parameter which changes
Ž
.
Ž
.
from 0.54 for R5Cl to y0.20 for R5tBu .

(
)
S. Lin et al.rJournal of Molecular Catalysis A: Chemical 136 1998 23–33
27
4. Conclusions
Unity Plus 500 spectrometer. Elemental Analy-
ses were performed by Desert Analytics or Eq
R Microanalytics Laboratory.
The results of this study indicate that the
Ž
polymerization behavior of bis 2-arylin-
.
denyl zirconium dichloride catalyst family is
5.2. Polymer analysis
relatively insensitive to substitution at the 4-
position. This observation stands in contrast to
our previous results, which show that substitu-
tion at the 3,5-position of the 2-aryl substituent
can have significant effects on the polymeriza-
tion behavior of 2-arylindene metallocenes. The
insensitivity of the catalyst to the 4-substitutent
suggests that this position may be utilized as a
point of attachment of the complex to a surface
as an entry into heterogeneous polymerization
systems that produce elastomeric polypropy-
lene.
Solution 13C NMR spectra were run at 75
MHz on a Varian Anova-300 NMR spectrome-
ter equipped with a 10 mm broad-band probe.
Samples were run as solutions in C2 D2Cl4r
C2 H2Cl4 at 1008C. Qualitative spectra were
acquired with f500–1000 transients with no
delay between pulses. Decoupling was always
on during acquisition, so the nuclear Overhauser
enhancement was present. High-temperature
GPC measurements of polymers were per-
formed at Amoco Chemical using a Watts 150C
GPC at 1008C in dichlorobenzene and refer-
enced to polypropylene standards.
5. Experimental
(
)
5.3. Preparation of 2- 4-methyl-C6 H4 indene
5.1. General procedures
A 3-neck 500-ml round-bottomed flask fitted
with a condenser and an addition funnel was
All experiments involving air-sensitive com-
pounds were performed under nitrogen in a
Vacuum Atmospheres or Braun drybox or under
argon using standard Schlenk line techniques.
Hydrocarbon solvents, diethyl ether, tetrahydro-
furan, and benzene-d6 were distilled from
sodiumrbenzophenone ketyl. Methylene chlo-
ride was distilled from calcium hydride. Deuter-
ated solvents were obtained from Cambridge
Isotope Labs.
Ž
.
charged with 2.66 g 0.11 mol of Mg turnings
and 20 ml of anhydrous Et2O. Slow addition of
Ž
.
a solution of 15.0 g 0.09 mol of 4-
Ž
.
bromotoluene in Et2O 100 ml , followed by
refluxing for 30 min, gave an orange solution of
the aryl Grignard reagent. The solution was
cooled to room temperature, filtered over a plug
of Celite, and the solvent was removed in vacuo
Ž
.
from the filtrate. Toluene 40 ml was added,
Butyllithium and 4-substituted aryl Grignards
were obtained from Aldrich and used as re-
ceived. 2-indanone was obtained from Aldrich
or Acros and depending on appearance, used as
received or purified by sublimation. ZrCl4 was
obtained from Fluka and used as received.
and the solution cooled to 08C, whereupon a
Ž
.
solution of 2-indanone 9.27 g, 0.07 mol in
Ž
.
toluene 70 ml was added dropwise to give an
orange slurry. This mixture was warmed to
room temperature and stirred for an additional 3
h. After cooling to 08C, it was quenched with
Ž
.
Ž
.
ZrCl4 THF was prepared according to litera-
150 ml of water. Hexane 150 ml was added,
and the reaction mixture neutralized with 5 M
HCl. The organic layer was separated, and the
aqueous layer was extracted with two 50-ml
portions of hexane. The combined organic lay-
ers were washed with two 50-ml portions of
2
ture procedures.
1H spectra were recorded on Varian Gemini
200, XL-400, or Varian Unity Plus 500 spec-
trometers while 13C NMR were recorded at 100
or 125 MHz on a Varian XL-400 or Varian

(
)
28
S. Lin et al.rJournal of Molecular Catalysis A: Chemical 136 1998 23–33
.
Ž
brine and dried over anhydrous magnesium sul-
fate. After filtration over Celite, the solvent was
Js6.8, 1H , 7.25–7.16 overlapping signals,
.
Ž
.
Ž
5H , 3.78 s, 2H, CH2 , 2.63 t, Js7.4, C H2-
CH 2CH 2CH 3 , 1.58 m, 2H, CH 2C H2-
Ž
.
.
Ž
removed in vacuo yielding 2- 4-methyl phenyl-
indanol as a solid.
.
.
Ž
CH 2 CH 3
,
1.58
m, 2H, CH 2 CH 2-
t, 3H, CH 2 CH 2-
Ž
Under argon, this alcohol and p-toluene-
C H 2 CH 3
,
0.94
13
Ž
.
Ä
4
Ž
sulfonic acid monohydrate 200 mg were dis-
CH2C H3.. C H NMR CDCl3, 198C 100
Ž
.
.
solved in benzene 200 ml , and the solution
was heated to reflux for 2 h. After cooling to
room temperature, the solvent was removed in
MHz : d 146.50, 145.55, 143.04, 142.50,
133.41, 128.73, 126.55, 125.63, 125.54, 125.23,
124.49, 123.59, 120.77, 38.99, 35.38, 33.57,
22.35, 13.97. C, H analysis: Anal. Found
Ž
.
vacuo and the product, 2- 4-methyl-C6H4 in-
Ž
.
Ž
.
Ž
.
dene, was recrystallized from Et2Orhexane.
Calcd : C, 91.31 91.88 , H, 8.08 8.12 .
1
Ž
.
Ž
Yield: 7.17 g 50% . H NMR CDCl3, 238C,
.
Ž
.
Ž
(
)
400 MHz : d 7.56 d, Js8 Hz, 2H ; 7.49 d,
5.6. Preparation of 2- 4-tert-butyl-C6 H4 indene
.
Ž
.
Js8 Hz, 1H ; 7.41 d, Js7 Hz, 1H ; 7.36–
Ž
.
7.14 overlapping signals integrating for 5H ;
Synthesis of this ligand was similar to that of
2- 4-methyl-C6H4 indene. Compound was re-
13
Ž
.
Ž
.
Ä 4
Ž
.
3.80 s, 2H, C H2 ; 2.40 s, 3H, C H3 . C H
NMR CDCl3, 238C, 100 MHz : d 146.5 s ,
145.5 s , 143.0 s , 137.4 s , 133.2 s , 129.4
Ž
.
Ž .
crystallized from diethyl etherrhexane at
1
Ž .
Ž .
Ž .
Ž .
Ž
y188C. Yields68%. H NMR CDCl3, 238C,
Ž .
Ž .
Ž .
Ž .
Ž .
.
Ž
.
Ž
s ; 126.6 s , 125.64 s , 125.57 s , 124.5 s ,
400 MHz : d 7.59 d, Js8.5 Hz, 2H , 7.47 d,
Ž .
Ž .
Ž
.
Ž
.
Ž
.
123.6 s , 120.8 s , 39.0 s, CH2 , 21.3 s,
CH3 . C, H analysis: Anal. Found Calcd. : C,
Js7 Hz, 1H , 7.42 d, Js8.5 Hz, 2H , 7.40
.
Ž
.
Ž
.
Ž
Ž
.
d, Js7 Hz, 1H , 7.28 dd, Js7 Hz, 1H ,
Ž
.
Ž
.
Ž
.
.
Ž
93.25 93.16 ; H, 7.00 6.84 .
7.20 s, 1H , 7.18 dd, Js7 Hz, 1H , 3.79 s,
t
13
.
Ž
.
.
Ž
2H , 1.36 s, 9H, Bu . C NMR CDCl3, 238C,
(
)
Ž .
Ž .
Ž .
5.4. Preparation of 2- 4-ethyl-C6 H4 indene
100 MHz : d 150.7 s , 146.4 s , 145.6 s ,
Ž .
Ž .
Ž
143.1 s , 133.2 s , 126.6 dd, JC – H s159 Hz,
2
Ž
.
.
Ž
.
Synthesis similar to 2- 4-methyl-C6H4 in-
dene. Recrystallized the yellow solid obtained
from ether to give white crystals, which were
JC – H s7 Hz , 125.8 d, JC – H s163 Hz , 125.6
2
Ž
.
Ž
dd, JC – H s157 Hz, JC – H s7 Hz , 125.4 dd,
JC – H s158 Hz, 2JC – H s7 Hz , 124.5 dd, JC – H
.
Ž
2
.
Ž
rinsed with hexanes and then dried. Yields
s159 Hz, JC – H s7 Hz , 123.6 dd, JC – H
s
1
2
Ž
.
.
Ž
32%. H NMR CDCl3, 208C, 200 MHz : d
158 Hz, JC – H s8 Hz , 120.8 dd, JC – H s159
2
Ž
Ž
.
.
Ž
.
.
Ž
7.56 d, Js8.2, 2H ; 7.46 d, Js7.2, 1H
Hz, JC – H s8 Hz , 39.0 td, JC – H s128 Hz,
2
Ž
.
Ž
Ž
. .
7.38 d, Js7.2, 1H , 7.25-7.16 overlapping
JC – H s 6 Hz, CH2 , 34.6 s, C CH3 3 ,
.
Ž
.
Ž
Ž
Ž
. .
signals, 5H , 3.77 s, 2H, C H2 , 2.63 q, Js
31.3. brq, JC – H s126 Hz, C CH3 3 . Anal.
.
Ž
.
Ž
.
Ž
.
Ž
.
7.2, C H2CH3 , 1.26 t, Js7.6, CH2C H3 .
found calcd. : C, 91.40 91.88 ; H, 7.98 8.12 .
13
Ä
4
Ž
.
C H NMR CDCl3, 198C, 100 MHz : d
146.48, 145.53, 143.81, 143.04, 133.47, 128.17,
126.55, 125.67, 125.63, 124.50, 123.60, 120.78,
38.99, 28.63, 15.54. C, H analysis: Anal. Found
(
5.7. Preparation of 2- 4-trimethylsilyl-
C6 H4 indene
)
Ž
.
Ž
.
Ž
.
Calcd : C, 92.68 92.68 , H, 7.35 7.31 .
A 3-neck round-bottom flask fitted with an
addition funnel was charged with 1,4-dibromo-
(
)
Ž
.
5.5. Preparation of 2- 4-n-butyl-C6 H4 indene
benzene 35.9 g, 0.152 mol under an N2 atmo-
sphere. After adding 150 ml of THF and cool-
Ž
Synthesis of this ligand was similar to that of
ing to y788C, n-butyllithium 100 ml, 0.16
2- 4-methyl-C6H4 indene. Yield s 28%. 1H
Ž
.
.
mol, 1.05 equivalents was added dropwise to
the reaction over 40 min to form a pale cream-
colored solution. After stirring for an additional
Ž
.
Ž
Ž
NMR CDCl3, 208C, 200 MHz : d 7.55 d,
.
Ž
.
Js8.2, 2H ; 7.46 d, Js8.2, 1H , 7.39 d,

(
)
S. Lin et al.rJournal of Molecular Catalysis A: Chemical 136 1998 23–33
29
Ž
Ž
.
10 min, trimethylchlorosilane 18.16 g, 0.167
125.7 dd, JC – H s161 Hz, JC – H s7 Hz , 125.6
.
Ž
.
Ž
mol, 1.10 equivalents was added over 15 min
to yield an olive-drab solution. The reaction was
warmed to y208C and quenched with 25 ml
MeOH. After washing with distilled water 3=
50 ml and drying over MgSO4, the crude prod-
uct was isolated by removing the solvent in
vacuo. Pure compound was obtained by distilla-
tion second fraction, 50–568Cr0.2 mmHg .
d, JC – H sca. 160 Hz , 125.5 d, JC – H sca.
.
Ž
.
.
160 Hz , 124.2 q, JC – F s272 Hz, CF3 , 123.8
Ž
Ž
dd, JC – H sca. 160 Hz, JC – H s9 Hz , 121.5
Ž
.
Ž
dd, JC – H s160 Hz, JC – H s9 Hz , 38.9 td,
2
.
.
JC – H s129 Hz, JC – H s7 Hz, CH2 . C, H
Ž
.
Ž
.
analysis: Anal. Found Calcd. : C, 74.05 73.84 ;
Ž
.
H, 4.15 4.26 .
Ž
.
Ž
.
(
)
Yields18.1 g 86% based on 2-indanone .
The indanol was formed and dehydrated in a
manner analogous to the other ligand syntheses
to yield 18 g of the crude indene. The product
was further purified by recrystallization from
5.9. Preparation of 2- 4-chloro-C6 H4 indene
Synthesis of this ligand was similar to that of
2- 4-methyl-C6H4 indene. Compound was re-
Ž
.
crystallized from diethyl ether at y188C. Over-
hexanes to yield 4.9 g 23.5% . 1H NMR
1
Ž
.
Ž
all yields32%. H NMR CDCl3, 208C, 200
Ž
.
Ž
.
.
Ž
.
Ž
Ž
CDCl3, 238C, 300 MHz : d 7.62 d, Js8.4
MHz : d 7.52 d, Js8.5, 2H ; 7.46 d, Js7.3,
.
Ž
Ž
.
.
Ž
.
Hz, 2H , 7.54 d, Js8.4 Hz, 2H , 7.48 d,
1H , 7.39 d, Js7.6, 1H , 7.33 d, Js8.6,
.
Ž
.
Ž
.
Ž
Js7 Hz, 2H , 7.40 d, Js7 Hz, 1H , 7.28
2H , 7.27 dd, Js7.32, 1H , 7.21–7.18 over-
Ž
.
Ž
.
Ž
Ž
Ä
.
.
Ž
dd, 2 Js7 Hz, 1H , 7.25 s, 1H , 7.18 dd,
lapping signals dd and singlet , 3H , 3.76 s,
13
.
Ž
.
Ž
.
4
Ž
2 Js7 Hz, 1H , 3.79 s, 2H , 0.287 s, 9H,
2H, C H2 . C H NMR CDCl3, 198C, 100
MHz : d 145.09, 145.05, 143.00, 134.44,
133.10, 128.80, 127.07, 126.78, 126.70, 124.99,
123.67, 121.09, 38.93. C, H analysis: Anal.
13
Ž
. .
Ä 4 Ž
C H NMR CDCl3, 198C, 100
.
Si CH3 3
.
.
MHz : d 146.43, 145.35, 143.18, 139.87,
136.29, 133.71, 126.74, 126.61, 124.90, 124.78,
123.66, 121.00, 38.90, y1.14. C, H analysis:
Ž
.
Ž
.
Ž
.
Found Calcd : C 79.47 79.48 , H 4.82 4.89 .
Ž
.
Ž
.
Anal. Found Calcd : C, 82.03 81.77 , H, 7.69
Ž
.
( (
)
7.62 .
5.10. Preparation of bis 2- 4-methyl-C6 H4 in-
denyl zirconium dichloride 2
)
( )
(
5.8. Preparation of 2- 4-trifluoromethyl-
)
Ž
C6 H4 indene
N-Butyllithium 1.6 M in hexanes, 4.2 ml,
.
6.7 mmol was added dropwise to a solution of
Ž
.
Ž
.
Synthesis of this ligand was similar to that of
2- 4-methyl-C6H4 indene 1.323 g, 6.4 mmol
Ž
.
Ž
.
2- 4-methyl-C6H4 indene. Caution: Fluori-
in Et2O 20 ml . The red-orange solution was
stirred at ambient temperature for 30 min, after
which time the solvent was removed in vacuo.
In a drybox, to the resulting solid was added
ZrCl4 0.754 g, 3.2 mmol . The solids were
cooled to y788C and methylene chloride 60
ml was slowly added. The solution was warmed
to room temperature and kept there overnight.
The resulting yellow-orange turbid solution was
then filtered over a plug of Celite and the Celite
was washed with CH2Cl2 until the washings
were colorless ca. 60 ml . The product was
recrystallized from CH2Cl2rhexane at y188C.
Yield: 577 mg 31% . H NMR C6D6, 238C,
nated phenyl Grignards can be explosive
w
x
when concentrated 18 . Compound was re-
Ž
crystallized from diethyl ether at y188C 5.59
1
.
Ž
.
Ž
.
g, 65% . H NMR CDCl3, 238C, 400 MHz : d
Ž
AB pattern centered at 7.68 ppm and integrating
Ž
.
Ž
.
for 4H, 7.51 d, Js7 Hz, 1H , 7.45 d, Js7
.
Ž
.
Ž
Hz, 1H , 7.35 s, 1H , 7.32 dd, 2 Js7 Hz,
.
Ž
Ž
.
Ž
.
1H , 7.25 dd, 2 Js7 Hz, 1H , 3.81 s, 2H .
13
.
C NMR CDCl3, 238C, 100 MHz : d 144.8
Ž .
Ž .
Ž .
Ž .
s , 144.7 s , 143.2 s , 139.3 s , one quater-
nary carbon is either masked by the aromatic
region, or is coincidental with the signal at
Ž
.
1
Ž
.
Ž
Ž
.
Ž
139.3 somewhat broad , 128.8 d, JC – H s168
.
Ž
.
.
Ž
.
Ž
Hz , 126.8 dd, JC – H s168 Hz, JC – H s7 Hz ,
400 MHz : d 7.36 d, Js8 Hz, 4H ; 7.11 m,

(
)
30
S. Lin et al.rJournal of Molecular Catalysis A: Chemical 136 1998 23–33
.
Ž
.
Ž
.
4H ; 7.02 d, Js8 Hz, 4H ; 6.92 m, 4H ; 6.43
133.46, 131.76, 128.65, 127.59, 127.18, 126.77,
125.8, 103.59, 29.17, 15.82. C, H analysis:
s, 4H, Cp–H ; 2.17 s, 6H, CH3 . 13C NMR
Ž
Ž
.
Ž
.
.
Ž
.
Ž
.
Ž
.
CD2Cl2, 238C, 100 MHz : d 139.3 m, qC ,
Anal. Found Calcd. : C 67.98 67.98 , H 5.06
Ž
.
Ž
.
Ž
Ž
.
134.0 m, qC , 130.5 qC , 129.9 dm, Js159
5.03 .
.
Ž
.
Ž
Hz, ArC–H , 127.0 brs, qC , 127.0 dd, Js
.
Ž
( (
)
159 Hz, Js7 Hz, ArC–H , 126.7 dd, Js162
5.12. Preparation of bis 2- 4-n-butyl-C6 H4 in-
.
Ž
)
( )
Hz, Js8 Hz, ArC–H , 125.2 dd, Js172 Hz,
denyl zirconium dichloride 4
.
Ž
Js5 Hz, ArC–H , 103.4 dd, Js176 Hz,
.
Ž
Js7 Hz, CpC–H , 21.5 qd, Js127 Hz, Js4
Synthesis of this complex was similar to that
.
Ž
Ž .
Hz, CH3 . C, H analysis crystallizes with 1r2
of 3 . Orange crystals were isolated with yield
Ž .
s16%. H NMR C6D6, 208C, 400 MHz : d
1
.
Ž
.
CH2Cl2 : Anal. Found Calcd. : C, 63.21
Ž
.
Ž
.
Ž . Ž
7.44 d, Js8.0 Hz, 4H ; 7.13 d, Js8.0 Hz,
63.46 ; H, 4.41 4.42 .
.
Ž
.
Ž
4H , 7.06 dd, Js6.4, 3.2, 4H , 6.92 dd,
( (
( )
)
.
Ž
.
Ž
5.11. Preparation of bis 2- 4-ethyl-C6 H4 inde-
Js6.4, 3.2, 4H , 6.47 s, 4H, Cp–H , 2.54 t,
)
.
Ž
nyl zirconium dichloride 3
Js7.6 Hz, C H2CH2CH2CH3, 2H , 1.57 m,
.
Ž
m ,
C H C H 2 C H C H , 4H , 1.31
2
2
3
Ž
. Ž
CH2CH2C H2CH3, 4H , 0.91 t, J s 7.6,
13
CH2C H3, 6H . C H NMR C6D6, 208C, 100
The corresponding indene 1.00 g, 4.54
mmol was slurried in dry diethyl ether in a 100
ml Schlenk flask under Ar. The solution was
cooled to y788C and n-butyllithium 2.18 ml,
5.45 mmol, 1.2 eq was added dropwise slowly.
The flask was brought to room temperature and
stirred for another hour, upon which the orange
solution was evaporated to give a reddish solid.
This solid was washed with 10 ml dry hexanes
and the now off-white solid isolated and dried.
After slurrying the lithium salt in 50 ml toluene
.
.
Ä
4
Ž
.
MHz : d 143.48 132.94, 129.03, 127.30, 126.93,
Ž
126.59, 126.04, 125.12, 124.8, 103.66, 35.95,
.
Ž .
34.01, 22.89, 14.38. Anal. Found Calcd. : C,
Ž
.
Ž
.
69.09 69.49 ; H, 5.81 5.89 .
( (
5.13. Preparation of bis 2- 4-tert-butyl-
)
)
( )
C6 H4 indenyl zirconium dichloride 5
Synthesis of this compound to similar to that
Ž
Ž .
and cooling to y788C, a slurry of ZrCl4 0.528
of 2 . Orange crystals were obtained by recrys-
1
.
g, 2.27 mmol in 20 ml toluene was cannula
tallization from toluene. Yields61%. H NMR
C6D6, 238C, 400 MHz : d AB pattern centered
at 7.42 ppm and integrating for 4H, AB pattern
centered at 6.96 ppm and integrating for 4H,
Ž
.
transferred into the flask. The reaction was
warmed to room temperature, during which is
turned from yellow to dark brown and became
turbid with salts. As the reaction progressed, the
insoluble lithium indenyl disappeared. Stirred
overnight at room temperature under Ar. Fol-
lowing filtration through a plug of Celite and
consequent washing of the Celite with 2=5 ml
toluene, the solution was concentrated down to
15–20 ml, and then placed in the y788C freezer
t
13
Ž
.
Ž
.
Ä 4
6.56 s, 4H, Cp–H , 1.30 s, 9H, Bu . C H
Ž
.
NMR C6D6, 238C, 100 MHz : d 151.7, 132.6,
130.9, 127.2, 126.8, 126.9, 126.6, 125.9, 125.1,
103.5, 34.7, 31.4. Anal. found calcd. crystal-
Ž
. Ž
.
Ž
.
lizes with 1r2 toluene : C, 71.11 71.12 ; H,
Ž
.
6.09 5.75 .
( (
5.14. Preparation of bis 2- 4-trimethylsilyl-
C6 H4 indenyl zirconium dichloride 6
for recrystallization. First recrystallization yield
1
Ž
.
Ž
Ž
)
)
( )
s482 mg 35% . H NMR C6D6, 208C, 400
.
.
Ž
MHz : d 7.14 d, Js8.4 Hz, 4H ; 7.08 d,
.
Ž
Ž
.
Ž
Js8 Hz, 4H , 6.92 m, 4H , 6.47 s, 4H,
Synthesis of this compound is similar to that
.
.
Ž .
Cp–H , 2.51 q, Js7.6 Hz, C H2CH3, 2H ,
of 2 except that the lithium salt and the cata-
13
Ž
.
Ä 4
1.15 t, Js7.6, CH2C H3, 3H . C H NMR
lyst were synthesized in toluene. The product
was extracted with CH2Cl2 and precipitated
Ž
.
C6D6, 208C, 100 MHz : d 151.49, 149.99,

(
)
S. Lin et al.rJournal of Molecular Catalysis A: Chemical 136 1998 23–33
31
from pentane. Further recrystallizations were
temperature during which is turned to a cloudy
straw-yellow and was stirred overnight under
Ar. The solvent was removed in vacuo and a
few milliliters of pentane were added which
were once again removed in vacuo. The yellow
solid was then extracted in 15 ml toluene and
filtered over a bed of celite. The toluene solu-
tion was then concentrated and placed in a
y188C freezer. Due to the low solubility of the
compound in toluene, methylene chloride was
used in further extractions of the solid left on
the frit. The methylene chloride washings were
collected, concentrated, and placed in y188C
freezer. The resulting solids were redissolved in
1
Ž
done in toluene. Yields78%. H NMR C6D6,
.
Ž
.
238C, 500 MHz : d 7.55 d, Js8.0 Hz, 4H ;
Ž
.
Ž
7.47 d, Js8.0 Hz, 4H , 7.06 dd, Js6.5, 3.0,
.
Ž
.
.
Ž
4H , 6.90 dd, Js6.5, 3.0, 4H , 6.53 s, 4H,
13
.
Ž
Ž
. .
Ä 4
Cp–H , 0.26 s, 9H, Si C H3 3
C H NMR
C6D6, 238C, 125 MHz : d 134.0, 128.3, 127.9,
126.9, 126.6, 125.4, 125.1 124.0, 103.6, 1.38.
Ž
.
Ž
.
Ž
.
Anal. found calcd. : C, 62.60 62.76 ; H, 5.72
Ž
.
5.56 .
( (
5.15. Preparation of bis 2- 4-trifluoromethyl-
)
)
( )
C6 H4 indenyl zirconium dichloride 7
Synthesis of this compound to similar to that
toluene and re-filtered to remove any residual
1
Ž .
Ž
.
Ž
of 2 . The product was recrystallized from
salts. Yields0.020 g 2% . H NMR C6D6,
Ž
.
. Ž
208C, 400 MHz : d 7.12 overlapping signals
toluene at y188C. Yield: 471 mg 35% . Note:
the compound is extremely insoluble. H NMR
1
. Ž .
consisting of a doublet and a multiplet m, 8H ,
7.02 d, Js8.6, 4H , 6.86 dd, Js6.5, 3.0,
4H , 6.17 s, 4H, Cp–H . C H NMR C6D6,
Ž
.
Ž
Ž .
Ž
Ä
C6D6, 238C, 400 MHz : d 7.36 d, Js8 Hz,
13
.
Ž
.
.
Ž
.
4
Ž
4H ; 7.12 dd, Js6.5 Hz, Js3.1 Hz, 4H ;
Ž
.
Ž
.
7.09 d, Js8 Hz, 4H ; 6.86 dd, Js6.4 Hz,
188C, 100 MHz : d 151.51, 134.83, 132.05,
13
.
Ž
.
Ä 4
Js3 Hz, 4H ; 6.21 s, 4H, Cp–H . C H
129.21, 128.60, 127.69, 127.20, 126.74, 125.37,
Ž
.
Ž .
NMR CD2Cl2, 238C, 100 MHz : d 136.7,
103.07. C, H analysis: Anal. Found Calc : C
Ž
.
Ž
.
Ž
.
132.7, 130.4 q, JC – F s33 Hz , 129.2, 127.3,
58.63 58.73 , H 3.47 3.28 .
Ž
.
Ž
127.2, 125.9 m , 125.4, 124.4 q, JC – F s272
.
Ž
.
Hz, CF3 , 103.7 Cp C–H . C, H analysis:
Ž
.
Ž
.
Anal. Found Calcd. : C, 56.42 56.47 ; H, 3.00
6. General procedure for solution poly-
merization of propylene
Ž
.
2.96 .
( (
)
5.16. Preparation of bis 2- 4-chloro-C6 H4 in-
y
5
w x
Zr s5=10
w
x w x
M, Al r Zr s1000, Poly-
)
( )
denyl zirconium dichloride 8
merization temps208C, Final volumes100 ml
75 ml toluene, 25 ml catalyst solution .
Ž
.
Ž
The corresponding indene 0.750 g, 3.31
mmol was slurried in ;10 ml dry tetrahydro-
furan in a 50 ml Schlenk flask under Ar. The
.
6.1. Catalyst solution
solution was cooled to y788C and added drop-
Ž
wise to a slurry of potassium hydride 0.077 g,
In a nitrogen dry box, catalyst stock solution
in toluene is prepared in a 25 ml volumetric
.
4.76 mmol, 1.4 eq in ;20 ml tetrahydrofuran.
6
The flask was brought to room temperature and
stirred for another 2 1r2 h upon which the dark
yellow solution was filtered via cannula into a
flask and an aliquot containing 5=10y mol
removed and diluted to 10 ml in a volumetric
Ž
. Ž
flask. Methylaluminoxane Akzo, Type IV 275
Ž
.
Ž
.
flask containing ZrCl4 THF
0.620 g, 1.64
mg is dissolved in 10 ml toluene. The catalyst
2
.
mmol, 0.49 eq in ;30 ml THF at y788C.
Another few milliliters of THF were added to
the excess KH to insure complete transfer of the
indene salt. The reaction was warmed to room
solution is added to the MAO solution, produc-
ing an orange-gold color almost immediately.
This solution is stirred for several minutes and
then introduced to a stainless steel, double-ended

(
)
32
S. Lin et al.rJournal of Molecular Catalysis A: Chemical 136 1998 23–33
Ž
Ž
.
injection tube containing 5 ml toluene final
injection tube final volume 20 ml . The tube is
brought out of the box and pressure with Ar to
prevent any air from being introduced.
.
volume 25 ml .
6.2. Polymerization
7.2. Polymerization
A 300-ml stainless steel Parr reactor was
purged several times with propylene by pressur-
izing and then venting. The regulator attached
to the reactor was set to the desired propylene
A 300-ml stainless steel Parr reactor is dried
and evacuated overnight. After filling with Ar
and then flushing with gaseous propylene at
least three times, 80 ml of liquid propylene is
introduced to the reactor. The contents are
maintained at 18–198C using a cooling
bathrcooling coil and allowed to remain at that
temperature for at least 10 min with stirring
Ž
pressure, the 75 ml toluene loaded in a stain-
.
less steel tube in the box was injected, and the
temperature set to 208C. This toluene solution
was allowed to equilibrate for at least 10 min at
the set pressure and temperature. Then the auto-
clave was vented until the pressure was 10 psig
less than the regulator pressure setting. The
catalyst solution was injected under propylene
pressure and the polymerization temperature
kept to 208C. After 1 h, the polymerization was
stopped by injection of 20 ml methanol and the
reactor slowly vented. The polymer was precipi-
Ž
.
usually Ps124–126 psig . A single-ended in-
jection tube containing 20 ml of catalystrMAO
solution in toluene is pressured to 200–250 psig
with Ar and the solution injected into the reac-
tor. The temperature is quickly brought to 208C
and kept there through the reaction. The pres-
sure drops initially, then stabilizes around 110–
113 psig. The reaction is quenched using 10 ml
of MeOH under Ar pressure when the pressure
Ž
tated by adding 200 ml acidified methanol 5%
.
HClrMeOH vrv and collected by filtration.
After drying in the vacuum oven for 18 h, it
Ž
has dropped 2–4 psig 20–40 min depending on
was weighed and analyzed by 13C NMR.
.
the catalyst and the reactor slowly vented. The
polymer is removed and stirred in 5% acidic
MeOH for several hours or overnight. It is then
dried overnight at 408C in a vacuum oven and
weighed.
7. General procedure for liquid propylene
polymerization
MX Al r Zr s1000, Poly-
x w x
y
5
w x
Zr s5=10
w
merization temps208C, Final volumes100 ml
80 ml liquid propylene, 20 ml catalyst solution .
Acknowledgements
Ž
.
This research was supported by Amoco
Chemical.
7.1. Catalyst solution
In a nitrogen dry box, catalyst stock solution
in toluene is prepared in a 25-ml volumetric
6
flask and an aliquot containing 5=10y mol
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Ž
.
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w x
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.
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.
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)
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.
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.
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Ž
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