Synthesis of unbridged bis(2-R-indenyl)zirconocenes containing functional groups and investigations in propylene polymerization

Article abstract of DOI:10.1021/om990083w

Five new indenyl zirconium metallocenes with 2-alkyl and 2-aryl substituents were synthesized and characterized. For the synthesis of the ligand the di-Grignard reagent 1,2-bis(magnesiomethyl)benzene dichloride was explored as a synthon to 2-substituted indenes. This procedure provides access to a variety of functionalized 2-indenylmetallocenes such as bis(2-ferrocenylindene)zirconium dichloride and bis(2-adamantylindenyl)zirconium dichloride. Crystallographic characterization of bis[2-(4-(dimethylamino)phenyl)indenyl] zirconium dichloride revealed an anti conformation with a coplanar orientation of the dimethylamino substituent to the aryl ring in the solid state. The polymerization behavior of all five zirconocene dichlorides in liquid propylene was studied in the presence of MAO at various temperatures, and the results were compared to those for the known catalyst system bis-(2-phenylindenyl)zirconium dichloride/MAO (M1/MAO). The productivity of the 2-arylindene metallocenes in propylene polymerization was on the order of 100-7000 kg of PP/((mol of Zr) h). In contrast, the (2-adamantylindenyl)metallocenes exhibited very low productivities of 6 kg PP/((mol of Zr) h) in propylene polymerization.

Full text of DOI:10.1021/om990083w

Organometallics 1999, 18, 4147-4155
4147
Syn th esis of Un br id ged Bis(2-R-in d en yl)zir con ocen es
Con ta in in g F u n ction a l Gr ou p s a n d In vestiga tion s in
P r op ylen e P olym er iza tion
Peter Witte, Tapan K. Lal, and Robert M. Waymouth*
Department of Chemistry, Stanford University, Stanford, California 94305
Received February 9, 1999
Five new indenyl zirconium metallocenes with 2-alkyl and 2-aryl substituents were
synthesized and characterized. For the synthesis of the ligand the di-Grignard reagent 1,2-
bis(magnesiomethyl)benzene dichloride was explored as a synthon to 2-substituted indenes.
This procedure provides access to a variety of functionalized 2-indenylmetallocenes such as
bis(2-ferrocenylindene)zirconium dichloride and bis(2-adamantylindenyl)zirconium dichloride.
Crystallographic characterization of bis[2-(4-(dimethylamino)phenyl)indenyl] zirconium
dichloride revealed an anti conformation with a coplanar orientation of the dimethylamino
substituent to the aryl ring in the solid state. The polymerization behavior of all five
zirconocene dichlorides in liquid propylene was studied in the presence of MAO at various
temperatures, and the results were compared to those for the known catalyst system bis-
(2-phenylindenyl)zirconium dichloride/MAO (M1/MAO). The productivity of the 2-arylindene
metallocenes in propylene polymerization was on the order of 100-7000 kg of PP/((mol of
Zr) h). In contrast, the (2-adamantylindenyl)metallocenes exhibited very low productivities
of 6 kg PP/((mol of Zr) h) in propylene polymerization.
In tr od u ction
Since the discovery that group 4 metallocenes could
be activated by methylaluminoxane (MAO) to polymer-
ize propylene, the field of metallocene design has
dramatically expanded.1-3 Group 4 metallocenes have
been developed to produce atactic, isotactic, hemiiso-
tactic, syndiotactic, and stereoblock polypropylene.3
The synthesis of elastomeric polypropylene using
metallocene catalysts was first reported by Chien and
co-workers with a stereorigid chiral ansa-titanocene.4-6
Collins has also developed a family of chiral metal-
locenes for the production of elastomeric polypropylene.7-9
We have been investigating a class of unbridged bis(2-
arylindene)metallocenes for the synthesis of stereoblock
elastomeric polypropylenes.10-17 These catalysts were
F igu r e 1. Proposed mechanism for formation of stereo-
block polypropylene.
designed to interconvert between chiral and achiral
torsional isomers18-20 on the time scale of the polym-
erization reaction in order to produce an isotactic and
atactic stereoblock structure (Figure 1). The nature of
the substituent in the 2-position of the indenyl ligand
is crucial; unbridged bis(indenyl)zirconium dichloride/
MAO and a variety of bis(2-alkylindenyl)zirconocenes
produce atactic polypropylenes.14,21-23
(1) Ewen, J . A. J . Am. Chem. Soc. 1984, 106, 6355-6364.
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P. Angew. Chem., Int. Ed. Engl 1985, 24, 507-508.
(3) Brintzinger, H. H.; Fischer, D.; Muelhaupt, R.; Rieger, B.;
Waymouth, R. M. Angew. Chem., Int. Ed. Engl. 1995, 34, 1143-1170.
(4) Mallin, D. T.; Rausch, M. D.; Lin, Y. G.; Dong, S.; Chien, J . C.
W. J . Am. Chem. Soc. 1990, 112, 2030-2031.
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1991, 113, 8570-8571.
(14) Petoff, J . L. M.; Bruce, M. D.; Waymouth, R. M.; Masood, A.;
Lal, T. K.; Quan, R. W. Organometallics 1997, 16, 5909-5916.
(15) Lin, S.; Hauptmann, E.; Lal, T. K.; Waymouth, R. M.; Quan,
R. W.; Ernst, A. B. J . Mol. Catal. A 1998, 136, 23-33.
(16) Petoff, J . L. M.; Waymouth, R. M. Polym. Prepr. 1998, 39(1),
212.
(17) Kravchenko, R.; Masood, A.; Waymouth, R. M.; Myers, C. L. J .
Am. Chem. Soc. 1998, 120, 2039-2046.
(18) Erker, G.; Nolte, R.; Krueger, C.; Schlund, R.; Benn, R.;
Grondey, H.; Mynott, R. J . Organomet. Chem. 1989, 364, 119-132.
(19) Erker, G.; Aulbach, M.; Knickmeier, M.; Wingbermuhle, D.;
Kruger, C.; Nolte, M.; Werner, S. J . Am. Chem. Soc. 1993, 115, 4590-
4601.
(6) Babu, G. N.; Newmark, R. A.; Cheng, H. N.; Llinas, G. H.; Chien,
J . Macromolecules 1992, 25, 7400-7402.
(7) Gauthier, W. J .; Corrigan, J . F.; Taylor, N. J .; Collins, S.
Macromolecules 1995, 28, 3771-3778.
(8) Gauthier, W. J .; Collins, S. Macromolecules 1995, 28, 3779-3786.
(9) Bravakis, A. M.; Bailey, L. E.; Pigeon, M.; Collins, S. Macromol-
ecules 1998, 31, 1000-1009.
(10) Coates, G. W.; Waymouth, R. M. Science 1995, 267(5195), 217-
219.
(11) Hauptman, E.; Waymouth, R. M.; Ziller, J . W. J . Am. Chem.
Soc. 1995, 117, 11586-11587.
(12) Kravchenko, R.; Masood, A.; Waymouth, R. M. Organometallics
1997, 16, 3635-3639.
(20) Knickmeier, M.; Erker, G.; Fox, T. J . Am. Chem. Soc. 1996,
118, 9623-9630.
(21) Resconi, L.; Abis, L.; Franciscono, G. Macromolecules 1992, 25,
6814-6817.
(13) Bruce, M. D.; Coates, G. W.; Hauptman, E.; Waymouth, R. M.;
Ziller, J . W. J . Am. Chem. Soc. 1997, 119, 11174-11182.
10.1021/om990083w CCC: $15.00 © 1999 American Chemical Society
Publication on Web 09/01/1999

4148 Organometallics, Vol. 18, No. 20, 1999
Ta ble 1. Nu m ber in g Sch em e a n d Yield of Liga n d s a n d Zir con ocen e Dich lor id es
Witte et al.
Sch em e 1. Liga n d Syn th esis
As part of our investigations on the polymerization
behavior of unbridged indenylmetallocenes, we have
examined the effects of 1-substitution on the indene,12
the nature of the metal atom,13 the ligand aromaticity,14
and the steric and inductive effect of the aryl substitu-
ent11,15 on the polymerization behavior. We present here
a further study of the influence of the 2-substituent with
particular regard to aryl substituents containing het-
eroatoms and sterically demanding substituents such
as an adamantyl group. Five new 2-substituted inde-
nylzirconocenes have been synthesized (Table 1: M2-
M6), characterized, evaluated, and compared to bis(2-
phenylindenyl)zirconium dichloride (M1) in propylene
homopolymerization.
Sch em e 2. Meta llocen e Syn th esis
versatile way to synthesize a variety of 2-substituted
indenes in reasonable to good yields (Table 1). The
starting methyl esters, if not commercially available,
were synthesized by nucleophilic attack of the carboxylic
acid on iodomethane.27,28
The synthesis of the zirconocenes M2-M6 from the
corresponding indenes 2-6 was straightforward, through
deprotonation of the ligand with n-butyllithium and
reaction of the lithium salt of the ligand with zirconium
tetrachloride in toluene (Scheme 2, Table 1).
Crystallization of bis[2-(4-(dimethylamino)phenyl)-
indenyl]zirconium dichloride (M3) from methylene chlo-
ride/pentane at room temperature gave crystals suitable
for X-ray structural analysis. M3 crystallizes in a anti
conformation (Figure 2), and shows many similarities
to the structure of rac-bis(2-phenylindenyl)zirconium
dichloride29 (r a c-M1).10 The dihedral angle between the
Cp and the attached phenyl plane is small (11.16°); the
Cp-Zr-Cp angle is 133°, so that the dihedral angle
between the two phenyl planes is 24.68°. The dimethy-
lamino group is tilted by a very small angle (3.0-4.6°)
relative to the phenyl plane. Only one rotamer of the
Resu lts
Bis(2-phenylindenyl)zirconium dichloride (M1) was
synthesized according to a literature procedure.10,13 This
method involves nucleophilic attack of phenylmagne-
sium bromide on 2-indanone. A major drawback of this
method is the susceptibility of 2-indanone to enoliza-
tion.23 This is particularly troublesome for most orga-
nolithium nucleophiles as well as sterically demanding
nucleophiles. In our efforts to prepare 2-ferrocenylin-
dene24 (5) we searched for a complementary approach
that would accommodate the introduction of more
sterically demanding substituents at the 2-position. We
found that this could easily be realized by reaction of
the di-Grignard reagent 1,2-di(magnesiomethyl)benzene
dichloride, first reported by Lappert et al.,25 with the
corresponding methyl ester of the sterically demanding
substituent (Scheme 1). This method has been applied
by Ellis et al. for the synthesis of 2,2′-bis(indenyl)-
biphenyl.26 As shown below, this method proved a
(22) Kimura, K.; Takaishi, K.; Matsukawa, T.; Yoshimura, T.;
Yamazaki, H. Chem. Lett. 1998, 571-572.
(26) Ellis, W. W.; Hollis, T. K.; Odenkirk, W.; Whelan, J .; Ostrander,
R.; Rheingold, A. L.; Bosnich, B. Organometallics 1993, 12, 4391-4401.
(27) Moore, G. G.; Foglia, T. A.; McGahan, T. J . J . Org. Chem. 1979,
44, 2425-2429.
(23) Lee, G. Y.; Xue, M.; Kang, M. S.; Kwon, O. C.; Yoon, J .; Lee,
Y.; Kim, H. S.; Lee, H.; Lee, I. J . Organomet. Chem. 1998, 558, 11-
18.
(24) Plenio, H. Organometallics 1992, 11, 1856-1859.
(25) Lappert, M. F.; Martin, T. R.; Raston, C. L.; Skelton, B. W.;
White, A. H. J . Chem. Soc., Dalton Trans. 1982, 1959-1963.
(28) Ferrocenecarboxylic acid was synthesized from lithioferrocene
and dry ice.
(29) Coates, G. W. Ph.D. Thesis, Stanford University, 1994.

Unbridged Bis(2-R-indenyl)zirconocenes
Organometallics, Vol. 18, No. 20, 1999 4149
F igu r e 2. Perspective drawing of M3 with atom-numbering scheme.
Ta ble 2. Selected Bon d Len gth s (Å)a of M3
ride M1-M6 exhibit time-averaged C2 symmetry con-
sistent with rapid rotation of the indenyl ligands around
the indenylzirconium vector. M1 is known to show no
coalescence for the cyclopentadienyl protons down to
-100 °C.13 Although the Cp proton peaks begin to
broaden below -60 °C, no decoalescence was observed
for M2-M4 down to a temperature of -110 °C (500
MHz, methylene chloride-d2). At room temperature the
Cp protons of the adamantyl-substituted M6 appear as
a sharp single resonance at 5.86 ppm. This resonance
begins to broaden below -60 °C and disappears at -100
°C, indicating the onset of decoalescence near this
temperature.
Propylene polymerizations were carried out in the
presence of the zirconocene dichlorides M1-M6 and
MAO (Zr:Al ) 1:(1000 ( 150)) in toluene solution in
liquid propylene at several temperatures (Table 4).
Catalysts derived from metallocenes M1 and M4 exhibit
roughly comparable productivities; catalysts derived
from M2, M3, and M5 are 3-6 times less productive.31
Due to the very low productivity of M6 (6-7 kg of PP/
((mol of Zr) h), 20 °C), its polymerization behavior was
not investigated at different temperatures.
Zr-C1
Zr-C2
Zr-C3
Zr-C4
Zr-C5
av
2.614(3)
2.556(4)
2.562(3)
2.451(3)
2.517(3)
2.54
C13-N
N-C16
N-C17
Zr-Cl
1.385(4)
1.439(5)
1.446(6)
2.4252(9)
1.473(4)
C3-C10
a
Numbering scheme according to Figure 2.
Ta ble 3. Selected Bon d An glesa a n d Dih ed r a l
An gles (d eg) betw een Lea st-Squ a r es P la n esb for
M3 a n d r a c-M1
M3
rac-M110
Cl-Zr-Cl*
cp-Zr-cp′
C16-N-C17
96.70(5) Cl-Zr-Cl*
133c
cp-Zr-cp′
118.8(3)
95.44(4)
131c
plane 1-plane 2
11.16
plane 1-plane 2
plane 1*-plane 2*
plane 2-plane 2*
11.54
13.53
23.9
plane 2-plane 2*
24.7
Numbering scheme according to ORTEP of M3 and r a c-M1,10
a
b
respectively (Figure 2). Legend: plane 1 ) C1-C5, plane 1* )
C1*-C5*, plane 2 ) C10-C15, plane 2* ) C10*-C15*. c The angle
given is that between the centroids of the five-membered rings of
the indenyl ligands (cp ) plane 1, cp′ ) plane 1*) and the
zirconium atom.
The weight-average molecular weights (Mw) of the
produced polypropylenes are in the range of Mw
)
two possible anti conformations was found in the crystal,
in contrast to M1, where anti and syn rotamers are
present in the unit cell.10,30 Table 2 contains selected
bond lengths of M3; Table 3 gives selected bond angles
and the dihedral angles between the cyclopentadienyl
and the phenyl planes.
100 000-860 000. All catalysts show a trend of lower
Mw with increasing polymerization temperature. The
molecular weight distributions of the polymers produced
from these catalysts are broad; the polymer derived from
M3 exhibited a very broad polydispersity (Mw/Mn
)
10.3) at 40 °C.32
The UV/vis absorption spectra of M1-M6 were mea-
sured in methylene chloride (Figure 3). A general
feature present in all spectra is the absorption at 280-
290 nm. While M1-M4 show a distinctive peak, M3 and
M5 exhibit the highest extinction coefficient (approxi-
mately ꢀmax ) 40 000 L/(mol cm). Most conspicuous is
the difference of the spectra of dimethylamino-substi-
tuted M3 relative to the other spectra with its intense
absorption at 330 nm (ꢀmax ) 37 980 L/(mol cm)) and
430 nm (ꢀmax ) 16 916 L/(mol cm)). The spectrum of M4
has a similar pattern with a less intense peak at 380
nm and a shoulder near 320 nm.
The isotacticity of the produced polymers was inves-
tigated by 13C NMR spectroscopy and is reported in
terms of the mole fractions of isotactic pentads
([mmmm]).33-35 The nature of the substituent in the
(31) The presence of some of the free ligand in the sample of
metallocene M3 may have resulted in an underestimation of the
productivity of this catalyst.
(32) The broad molecular weight distributions appear to be a general
trend for unbridged 2-arylindene catalysts that yield polymers of
intermediate isotacticity. For the polymers reported here, the GPC
traces are monomodal for all catalysts except M2, which shows a
shoulder on the high-molecular-weight end of the distribution. The
origin of these broad molecular weight distributions is not clear but is
the subject of ongoing investigations.
At room temperature, the 1H NMR (500 MHz) and
13C NMR (125 MHz) spectra of each zirconocene dichlo-
(33) For random (atactic) polypropylene, [mmmm] ) 6%; for pure
isotactic polypropylene, [mmmm] ) 100%.
(30) The preliminary X-ray structure of M4 indicates that it also
crystallizes in the rac conformation with both enantiomers in the unit
cell. Unfortunately, disorder in the crystal structure prevents a more
detailed comparison of the structures.
(34) Randall, J . C. Polymer Sequence Determination by the Carbon
13 NMR Method; Academic Press: New York, 1977.
(35) Koenig, J . L. Spectroscopy of Polymers; American Chemical
Society: Washington, DC, 1991.

4150 Organometallics, Vol. 18, No. 20, 1999
Witte et al.
F igu r e 3. UV/vis absorption spectra of M1-M6.
Ta ble 4. Su m m a r y of P olym er iza tion Beh a vior of M1-M6
productivity (kg of PP/
((mol of Zr) h)
e
entry
catalyst
temp (°C)
[mmmm]d (%)
[m] (%)
IR index
103Mw
Mw/Mn
1
M1
0
0
1850
3639
2496
2508
4165
4104
188
139
441
362
689
538
311
295
332
359
883
604
668
3180
2578
2643
6600
7158
763
667
885
783
607
476
6
38
39
39
39
29
30
75
75
71
70
62
61
44
43
53
51
53
48
84
85
77
76
73
72
37
37
40
38
37
38
20
21
72
74
73
73
67
69
90
89
87
87
83
82
76
74
79
79
77
74
95
95
93
92
91
91
79
80
76
75
73
74
54
55
0.41
0.37
0.34
0.35
0.30
0.31
0.80
0.84
0.77
0.74
0.70
0.62
0.56
0.45
0.55
0.45
0.60
0.53
0.83
0.78
0.74
0.72
0.77
0.79
0.40
0.40
0.34
0.32
0.37
0.36
c
461
651
539
518
169
157
691
514
423
509
199
189
372
368
243
209
140
108
451
718
731
661
418
462
451
521
278
264
107
106
c
2.8
2.9
4.7
3.3
3.4
3.3
8.7
5.9
8.5
7.4
12.0
8.0
4.0
3.7
5.9
5.2
10.6
10.4
3.9
3.3
3.3
3.0
4.6
3.7
4.5
2.9
3.0
3.2
2.6
2.7
c
2
3
20
20
40
40
0
4
5
6
7
M2
8
0
9
20
20
40
40
0
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
M3a
M4
0
20
20
40
40
0
0
20
20
40
40
0
M5b
0
20
20
40
40
20
20
M6
7
c
c
c
a
b
The metallocene fraction contained 0.415 mol of ligand/mol of metallocene. The metallocene fraction contained 0.585 mol of CH2Cl2/
mol of metallocene. c Not enough material for investigation. Determined by 13C NMR. e Determined by GPC versus polypropylene
d
standards.
2-position has a dramatic influence on the isotacticity
of the polymer. Metallocene M6 is the least stereospe-
cific of the unbridged catalysts investigated but pro-
duced so little polymer that the properties of these
materials could not be fully investigated. Metallocene
M5 exhibits behavior very similar to that of M1 at 0
and 20 °C but appears to exhibit less of a loss in
stereospecificity at 40 °C than does M1. The 3,5-aryl-
substituted metallocenes M2 and M4 produce a polymer
with a significantly higher isotactic pentad content (70-

Unbridged Bis(2-R-indenyl)zirconocenes
Organometallics, Vol. 18, No. 20, 1999 4151
80%). They also show the most obvious trend of lower
isotacticity with rising polymerization temperature. The
trends in the IR index (A998/A973), a measure of the
isotactic helical content,36-38 tracks the results obtained
from 13C NMR.
instance, introduction of methoxy or dimethylamino
groups onto the 2-aryl substituent does not dramatically
inhibit polymerization, although the productivity of the
bis-3,5-dimethoxy-substituted M2 is approximately 10
times less productive than the p-methoxy-substituted
M4. This difference might well be accounted for by the
shielding effect of the adjacent tert-butyl groups.
We had previously observed that the introduction of
a variety of substituents at the 4-positions of the 2-aryl
substituent had little influence on the stereospecificity
of unbridged (2-arylindenyl)metallocenes.15 The behav-
ior of metallocene M3 suggests that this may not be
general for substituents with strong π-donor abilities
such as the dimethylamino group. For example, while
the isotacticity of M3 is approximately equal to that of
M1 at a polymerization temperature of 0 °C, M3
exhibits a higher stereospecificity at both 20 and 40 °C
([mmmm] ) 53% relative to 39%). We had no means of
predicting the stereospecificity of the ferrocenyl-substi-
tuted metallocene M5. It is less productive but produces
a polymer with a tacticity similar to that produced by
the prototype metallocene M1.
We had also previously observed that introduction of
trifluoromethyl groups at the 3′,5′-positions of the 2-aryl
substituent lead to much higher isotacticities while the
3′,5′-dimethylphenyl-substituted metallocene behaved
very similarly to the (2-phenylindenyl)metallocene
M1.11,13 The observation that both the dimethoxy-
substituted M2 and the di-tert-butyl-substituted M4
yield more highly tactic polymers ([mmmm] from 70 to
85%) suggests that the influence of substituents at this
position is largely steric in origin. That is, substituents
larger than methyl in the 3,5-positions lead to higher
tacticities for these unbridged 2-arylindene metal-
locenes.
The very low productivity observed for the 2-adaman-
tyl-substituted M6 (6 kg of PP/((mol of Zr) h)) can be
contrasted to that reported14 for the bis(2-cyclohexylin-
denyl)zirconium dichloride metallocene (2340 kg of PP/
((mol of Zr) h)) and suggests that the rigid and sterically
demanding adamantyl substituent inhibits polymeri-
zation. The stereospecificities of 2-adamantyl (M6,
[mmmm] ) 20%) and 2-cyclohexyl ([mmmm] ) 15%)14,23
are only slightly different under comparable polymer-
ization conditions.
We have previously proposed a mechanism (Figure
1) involving the interconversion of isospecific and as-
pecific forms of the catalysts by means of torsional
isomerism18-20 of the indenyl ligands.10 To obtain a
stereoblock structure in the polymer chain by this
mechanism, the forms of the active catalyst must be
close in energy and the rate of interconversion must be
slower than insertion of the olefin but faster than the
time it takes to construct a single polymer chain.45
Changing the nature of the ligands is likely to alter
several factors at once and renders predictions of the
polymerization behavior of a given metallocene very
difficult. Nevertheless, the studies reported here, in
Discu ssion
Polymerization catalysts derived from bis(2-arylin-
denyl)zirconium dihalides are known to produce elas-
tomeric polypropylene in the presence of MAO. The
elastomeric properties of these materials have been
interpreted in terms of a stereoblock microstructure of
alternating atactic and isotactic diasterosequences.10-17
A full exploration of the steric and electronic effects on
propylene polymerization performance requires access
to a wide variety of ligand substitution patterns. In this
paper, we report a synthetic procedure utilizing the di-
Grignard reagent 1,2-di(magnesiomethyl)benzene dichlo-
ride25,26 as a precursor to a family of 2-substituted
indenes. The variety of commercially available methyl
ester and carboxylic acids provides access to a wide
range of new indene ligands. Metallocenes M2-M4
contain ligands with electron-donating substituents on
the 2-aryl substituents and varying steric demand. M5
contains a electron-poor aryl substituent with high
steric demand. M6 was synthesized to study the effect
of a bulky substituent without aromaticity.
The solid-state structure of the (dimethylamino)-
phenyl-substituted metallocene M3 reveals a closely
coplanar arrangement of the dimethylamino group and
the planes defined by the aryl and the indene groups.
The dihedral angles between the indenyl and the phenyl
planes are on the order of 10-12°, and the small
torsional angles (C12-C13-N-C16 ) -4.6° and C14-
C13-N-C17 ) 3.0°) of the dimethylamino group are
indicative of some conjugation of the nitrogen lone pair
into the 2-arylindene ligand. The bond length between
the N-atom of the dimethylamino group and the C-atom
of the phenyl ring (1.385 Å) is between the bond lengths
found for the directly substituted bis[2-(dimethylamino)-
indenyl]zirconium dichloride (1.354 Å)39-41 and their
bridged ansa analogues (1.397-1.406 Å)39,41 and is
indicative of some double-bond character. The extended
conjugation engendered by the p-dimethylamino group
is further indicated by the UV absorption spectra of
metallocene M3, which exhibit absorption bands at 430
and 317 nm.
The polymerization behavior of (2-arylindene)metal-
locenes M2-M6 reveals that all but M6 are competent
propylene polymerization catalysts. It is becoming quite
clear that a variety of functional groups can be intro-
duced into appropriate positions of metallocene ligands
without significant loss in activity.39,42-44 In the present
(36) For highly isotactic polypropylene the IR index approaches
unity.
(37) Luongo, J . P. J . Appl. Sci. 1960, 3, 302-309.
(38) Collette, J . W.; Ovenall, D. W.; Buck, W. H.; Ferguson, R. C.
Macromolecules 1989, 22, 3858-66.
(39) Barsties, E.; Schaible, S.; Prosenc, M.-H.; Rief, U.; Roell, W.;
Weyand, O.; Dorer, B.; Brintzinger, H.-H. J . Organomet. Chem. 1996,
520, 63-68.
(43) Leino, R.; Luttikhedde, H. J . G.; Lehtonen, A.; Ekholm, P.;
Nasman, J . H. J . Organomet. Chem. 1998, 558, 181-188.
(44) Leino, R.; Luttikhedde, H. J . G.; Lehtonen, A.; Sillanpaa, R.;
Penninkangas, A.; Stranden, J .; Mattinen, J .; Nasman, J . H. J .
Organomet. Chem. 1998, 558, 171-179.
(40) Luttikhedde et al. report a structure with two different C-N
bond lengths for the same compound.41
(41) Luttikhedde, H. J . G.; Leino, R. P.; Wilen, C. E.; Naesmann, J .
H. Organometallics 1996, 15, 3092-3094.
(42) Luttikhedde, H. J . G.; Leino, R.; Ahlgren, M. J .; Pakkanen, T.
A.; Naesman, J . H. J . Organomet. Chem. 1998, 557, 227-230.
(45) Coleman, B. D.; Fox, T. G. J . Chem. Phys. 1963, 38, 1065-
1075.

4152 Organometallics, Vol. 18, No. 20, 1999
Witte et al.
charged with 4.00 g (21.07 mmol) of ferrocene and 0.30 g (2.67
mmol) potassium tert-butoxide, evacuated, and purged with
argon three times. THF (200 mL) was added and the mixture
stirred at room temperature until all solids were completely
dissolved. After the reaction mixture was cooled to -78 °C,
24.8 mL (42.15 mmol) of tert-butyllithium (1.7 M in pentane)
conjunction with our other observations on the ligand
effects of unbridged indenylmetallocenes,10-17 are begin-
ning to illuminate some of the basic structure/activity
relationships for this class of metallocene catalysts.
Con clu sion s
was added dropwise over
a period of 15 min, with the
temperature maintained below -70 °C. The mixture was
stirred at -78 °C for 60 min and then poured into a slurry of
dry ice (excess) and diethyl ether (not purified). The mixture
was warmed to room temperature and extracted with 0.75 M
sodium hydroxide solution (2 × 100 mL, 50 mL). The combined
aqueous layers were carefully neutralized with dilute hydro-
cloric acid (pH >4), and the resulting orange solid was
extracted with diethyl ether until the organic phase remained
colorless. The combined organic layers were filtered (to remove
traces of ferrocenedicarboxylic acid) and dried over magnesium
sulfate. The dried ether solution was concentrated, hexanes
was added, and the solution was again concentrated until the
acid precipitated. The orange solid was collected by filtration.
The concentration-filtering procedure was repeated several
A short and effective route to 2-substituted indenes
and their corresponding zirconocenes was developed.
Sterically demanding as well as functionalized aryl
substituents are easily introduced into the 2-position
of the indenyl ligand using a di-Grignard reagent as a
synthon.
Propylene polymerization studies reveal that methoxy
and dimethylamino substituents on the 2-arylindene
ligand do not dramatically inhibit the polymerization
activity and may exert some electronic influence on the
polymerization behavior of the metallocene catalysts.
Bis(2-ferrocenylindenyl)metallocenes are competent pro-
pylene polymerization catalysts and produce polymers
similar to that of the parent bis(2-phenylindenyl)-
zirconocene.
1
times. Yield: 4.72 g (20.52 mmol, 97%). H NMR (DMSO-d6):
δ 4.20 (s, 5H), 4.30 (t, J ) 1.9 Hz, 2H), 4.69 (t, J ) 1.9 Hz,
2H). 13C NMR (DMSO-d6): δ 69.51, 69.90, 71.07, 172.18.
Meth yl F er r ocen ylca r boxyla te. Substrate: ferrocenecar-
boxylic acid (vide supra), 4.688 g (20.38 mmol). Reaction
conditions: 20 h reflux; flash chromatography on silica gel with
10% ether in hexanes, then recrystallization from hexanes.
Exp er im en ta l Section
Gen er a l Con sid er a tion s. All experiments involving air-
sensitive compounds were performed under nitrogen in a
Vacuum Atmospheres drybox or under argon using standard
Schlenk line techniques. Toluene was passed over a column
of activated alumina and a supported copper (Q5) catalyst and
then degassed and stored under argon. All other solvents were
distilled from appropriate drying agents under a nitrogen
atmosphere and stored in Strauss flasks under an argon
atmosphere, unless otherwise indicated. Diethyl ether and
tetrahydrofuran (THF) were distilled from sodium/benzophe-
none. Methylene chloride and chloroform were distilled from
calcium hydride. Pentane and hexanes were distilled from
lithium aluminum hydride. Acetone was dried and distilled
over calcium sulfate (Drierite). Dry methylene chloride-d2 was
bought in 0.5 mL ampules from Cambridge Isotope Labora-
tories; chloroform-d3 was refluxed over calcium hydride,
vacuum-transferred, and stored under nitrogen. Organo-
lithium reagents were transferred to Strauss flasks and stored
at 4 °C under an argon atmosphere. All other chemicals and
reagents were bought from Aldrich or Alfa Aesar and used
without further purification unless specified otherwise.
Methyl esters were prepared by a slightly modified litera-
ture procedure.27
1
Yield: 4.511 g of an orange solid (18.48 mmol, 90%). H NMR
(CDCl3): δ 3.78 (s, 3H), 4.18 (s, 5H), 4.37 (t, J ) 1.8 Hz, 2H),
4.78 (t, J ) 1.8 Hz, 2H). 13C NMR (CDCl3): δ 51.57, 69.70,
70.06, 71.25, 172.22.
Meth yl 1-Ad a m a n ta n ylca r boxyla te. Substrate: 1-ada-
mantanecarboxylic acid, 3.619 g (19.87 mmol). Reaction condi-
tions: 20 h reflux; isolation and purification of the ester by
recrystallyzation from hexanes. Yield: 3.058 g of colorless
crystals (15.74 mmol, 79%). 1H NMR (CDCl3): δ 1.65-1.73 (m,
6H), 1.86 (d, J ) 3.0 Hz, 6H), 1.99 (s br, 3H), 3.62 (s, 3H). 13C
NMR (CDCl3): δ 27.94, 36.51, 40.71, 51.59.
Meth yl 3,5-Di-ter t-bu tyl-4-m eth oxyben zoa te. In con-
trast to the general procedure, 5.584 g (40 mmol) potassium
carbonate and 6.3 mL (100 mmol) iodomethane were reacted
with 2.554 g (10 mmol) of 3,5-di-tert-butyl-4-hydroxybenzoic
acid. Also, the reaction mixture was heated only to 45 °C for
30 h. Flash chromatography of the crude product on silica gel
with 7.5% ether in hexanes and then recrystallization from
hexanes at -20 °C gave the product. Yield: 2.213 g (7.95 mmol,
1
80%). H NMR (CDCl3): δ 1.42 (s, 18H), 3.68 (s, 3H), 3.87 (s,
3H), 7.93 (s, 2H). 13C NMR (CDCl3): δ 31.91, 35.86, 51.93,
64.40, 124.35, 128.24, 144.01, 163.84, 167.45.
1H and 13C NMR spectra were recorded on a Varian Inova
500 MHz or Varian Gemini 400 MHz spectrometer, UV/vis
spectra were recorded on a HP 845X UV/vis spectrometer.
Elemental analyses were performed by E + R Microanalytical
Laboratory.
Gen er a l P r oced u r e for t h e Syn t h esis of In d en yl
Liga n d s fr om th e Cor r esp on d in g Meth yl Ester s. The di-
Grignard reagent of o-xylylene dichloride was prepared with
reference to the literature procedure.26,47 Magnesium powder
(50 mesh, 1.167 g, 48.00 mmol) was dried in a 500 mL three-
necked, round-bottomed flask equipped with a pressue-equal-
izing addition funnel by heating to 120 °C under vacuum (10-
20 mTorr) overnight. After the mixture was cooled to room
temperature, the apparatus was repressurized with argon.
THF (10 mL) and 0.25 mL (3.00 mmol) of 1,2-dibromoethane
were added, and the mixture was heated with a heat gun. The
heating was stopped 1 min after gas evolution occurred. All
volatiles were removed in vacuo. After the apparatus was
purged with argon, 10 mL of THF was added and 2.101 g
(12.00 mmol) of o-xylylene dichloride (purified by Kugelrohr
distillation prior to use) was dissolved in 125 mL of THF in
the addition funnel while purging the apparatus was purged
with argon. The solution in the addition funnel was added
P olym er An a lysis. Solution 13C NMR spectra were run at
75 MHz on a Varian Inova 300 MHz spectrometer equipped
with
a 10 mm broad-band probe. Samples were run as
solutions in 1,1,2,2-tetrachloroethane containing about 0.5 mL
of 1,1,2,2-tetrachloroethane-d2 at 100 °C and 500-2000 tran-
sients were collected per sample. IR spectra were obtained
from polypropylene films on a Perkin-Elmer 1600 series FTIR.
High-temperature GPC measurements of polymers were per-
fomed at Amoco Chemical using a Waters 150C GPC at 100
°C in 1,2,4-trichlorobenzene and referenced to polypropylene
standards.
F er r ocen eca r boxylic Acid . Lithioferrocene was prepared
according to a literature procedure.46 A Schlenk tube was
(46) Sanders, R.; Mueller-Westerhoff, U. T. J . Organomet. Chem.
1996, 512, 219-224.
(47) Wakefield, B. J . Organomagnesium Methods in Organic Syn-
thesis; Academic Press: San Diego, CA, 1995; p 34.

Unbridged Bis(2-R-indenyl)zirconocenes
Organometallics, Vol. 18, No. 20, 1999 4153
dropwise over a period of 3-4 h, and the reaction mixture was
stirred vigorously for 15 h at room temperature. The magne-
sium was filtered off using a Schlenk frit under argon to yield
a pale green solution. The receiving flask was equipped with
a pressure-equalizing addition funnel, and the apparatus was
purged with a vigorous argon flow for 15 min. The methyl ester
(8 mmol) was dissolved in 65 mL of THF in the addition funnel
and added to the di-Grignard solution at -78 °C over ap-
proximately 60 min, with the temperature consistently main-
tained below -70 °C during the addition. The reaction mixture
was warmed to 0 °C over 1-2 h, and 80 mL of distilled water
was added through the addition funnel over 15-30 min. After
the reaction mixture was warmed to room temperature, the
THF was removed completely from the reaction mixture. The
remaining suspension was acidified to pH 1 and extracted with
methylene chloride. The combined organic layers were dried
over magnesium sulfate and stirred with 0.300 mg (1.57 mmol)
of p-toluenesulfonic acid hydrate for 1 h at room temperature.
After extraction with distilled water and drying over magne-
sium sulfate, the crude product was transferred to silica gel
and purified by flash chromatography.
2-F er r ocen ylin d en e (5). Substrate: Methyl ferrocenyl-
carboxylate, 3.851 g (15.78 mmol). Flash chromatography on
silica gel with hexanes. Yield: 3.229 g of amber crystals (10.76
mmol, 68%). 1H NMR (CD2Cl2): δ 3.67 (s, 2H), 4.09 (s, 5H),
4.33 (t, J ) 1.8 Hz, 2H), 4.58 (t, J ) 1.8 Hz, 2H), 6.82 (s, 1H),
7.12 (td, J ) 7.3 Hz, J ) 1.2 Hz, 1H), 7.22 (t, J ) 7.3 Hz, 1H),
7.29 (d, J ) 7.4 Hz, 1H), 7.43 (d, J ) 7.3 Hz, 1H). 13C NMR
(CD2Cl2): δ 40.16, 66.80, 69.44, 69.76, 81.23, 120.09, 123.79,
123.96, 124.00, 126.82, 143.11, 146.39, 147.80.
organic layer was dried over magnesium sulfate, and the
toluene was removed. The crude product was purified by flash
chromatography on silica gel with hexanes. Yield: 1.164 g of
brilliant white solid (4.65 mmol, 56%). 1H NMR (CD2Cl2): δ
1.75 (dt br, J ) 11.5 Hz, J ) 3.0 Hz, 3H),1.79 (dr br, J ) 12
Hz, J ) 3.0 Hz, 3H), 1.86 (d, J ) 3 Hz, 6H), 2.05 (s br, 3H),
3.72 (t, J ) 0.8 Hz, 2H), 6.49 (sx, J ) 0.5 Hz, 1H), 7.07 (td, J
) 7.5 Hz, J ) 1.0 Hz, 1H), 7.19 (td, J ) 7.5 Hz, J ) 0.5 Hz,
1H), 7.26 (d, J ) 7.0 Hz, 1H), 7.38 (dq, J ) 7.5 Hz, J ) 0.8 Hz,
1H). 13C NMR (CD2Cl2): δ 29.19, 35.79, 37.04, 37.25, 43.14,
120.31, 123.15, 123.76, 123.79, 126.43, 143.36, 145.92, 161.29.
Gen er a l P r oced u r e for th e Syn th esis of th e In d e-
n ylzir con iu m Dich lor id es th r ou gh th e Rea ction of th e
Lith iu m Sa lt w ith Zir con iu m Tetr a ch lor id e. The ligand
(1.5 mmol) was dissolved in 30-50 mL of diethyl ether. The
solution was cooled to 0 °CC, and 0.6 mL (1.5 mmol) of
n-butyllithium (2.5 M in hexanes) was added via syringe
dropwise. After the addition the cooling bath was removed and
the mixture was stirred at ambient temperature for 10 h. All
volatiles were removed in vacuo, and the evacuated reaction
flask was brought into a nitrogen glovebox. Zirconium tetra-
chloride (175 mg, 0.75 mmol) was added. Outside the box, 60-
100 mL of toluene was added via cannula and the reaction
mixture stirred vigorously at room temperature for 3 days.
Again, all volatiles were removed in vacuo and 50 mL of
methylene chloride was added. The suspension was filtered
over Celite through a Schlenk frit under argon. The Celite was
washed with methylene chloride until the filtered liquid
remained colorless. The resulting clear solution’s volume was
reduced to one-fourth to one-fifth its original volume, and a
layer of pentane, hexanes, or diethyl ether was applied
carefully. The layered solution was stored at room temperature
or -80 °C for crystallization of the product. After crystalliza-
tion, the liquid was filtered off via cannula and the remaining
solid was dried in vacuo. The filtrate was eventually concen-
trated to obtain a second crop. Alternately, all volatiles of the
filtrate were removed in vacuo, the solid was redissolved in a
small amount of methylene chloride, and the solution was
filtered via cannula and layered again.
2-(3,5-Dim eth oxyp h en yl)in d en e (2). Substrate: Methyl
3,5-dimethoxybenzoate, 1.568 g (8.00 mmol). Flash chroma-
tography on silica gel with 5% ether in hexanes. Yield: 0.899
g of brilliant white needlelike crystals (3.56 mmol, 45%). 1H
NMR (CD2Cl2): δ 3.78 (s, 2H), 3.83 (s, 6H), 6.40 (t, J ) 2.2
Hz, 1H), 6.80 (d, J ) 2.3 Hz, 2H), 7.18 (td, J ) 7.4 Hz, J ) 1.2
Hz, 1H), 7.25 (s, 1H), 7.26 (t, J ) 7.0 Hz, 1H), 7.40 (d, J ) 7.4
Hz, 1H), 7.48 (d, J ) 7.3 Hz, 1H). 13C NMR (CD2Cl2): δ 39.48,
55.68, 99.81, 104.14, 121.30, 123.98, 125.22, 126.90, 127.35,
129.57, 138.42, 143.57, 146.76, 161.39.
Bis[2-(3,5-dim eth oxyph en yl)in den yl]zir con iu m Dich lo-
r id e (M2). Ligand: 2-(3,5-dimethoxyphenyl)indene, 524 mg
(2.08 mmol). Yield: 336 mg (0.51 mmol, 50%), dark yellow
2-[4-(Dim et h yla m in o)p h en yl]in d en e (3). Substrate:
Methyl 4-(dimethylamino)benzoate, 1.707 g (9.33 mmol). Flash
chromatography on silica gel with 50% methylene chloride in
hexanes. Yield: 1.638 g of a pearl-colored solid (6.96 mmol,
1
solid. H NMR (CD2Cl2): δ 3.86 (s, 12H), 6.53 (t, J ) 2.5 Hz,
2H), 6.62 (s, 4H), 6.73 (d, J ) 2.5 Hz, 4H), 7.11-7.15 (m, 4H),
7.18-7.21 (m, 4H). 13C NMR (CD2Cl2): δ 55.82, 101.00, 104.89,
105.41, 125.14, 127.18, 128.78, 132.20, 135.23, 161.62. Anal.
Calcd for C34H30Cl2O4Zr: C, 61.43; H, 4.55. Found: C, 61.18;
H, 4.44.
1
75%). H NMR (CD2Cl2): δ 2.98 (s, 6H), 3.75 (s, 2H), 6.73 (dt,
J ) 9.0 Hz, J ) 2.5 Hz, 2H), 7.02 (d, J ) 0.5 Hz, 1H), 7.10 (td,
J ) 7.5 Hz, J ) 1.0 Hz, 1H), 7.22 (tt, J ) 7.5 Hz, J ) 0.5 Hz,
1H), 7.32 (d, J ) 7.5 Hz, 1H), 7.43 (dd, J ) 7.5 Hz, J ) 1.0 Hz,
1H), 7.53 (dt, J ) 9.0 Hz, J ) 2.5 Hz, 2H). 13C NMR (CD2Cl2):
δ 39.72, 40.56, 112.58, 120.39, 122.69, 123.77, 124.08, 124.48,
126.78, 126.92, 143.17, 146.52, 147.44, 150.55.
Bis[2-(4-(d im et h yla m in o)p h en yl)in d en yl]zir con iu m
Dich lor id e (M3). Ligand: 2-[4-(dimethylamino)phenyl]in-
dene, 512 mg (2.18 mmol). In contrast to the general procedure,
the lithium salt was prepared in 60 mL of toluene with 0.78
mL of n-butyllithium (2.5 M in hexanes, 1.95 mmol). After the
mixture was stirred for 10 h at room temperature, the toluene
was removed in vacuo, the evacuated Schlenk tube was
brought into a nitrogen glovebox,and 232 mg (1.00 mmol) of
zirconium tetrachloride was added. Outside the box, 80 mL of
toluene was added via cannula and the reaction mixture
stirred at room temperature resulting in a very cloudy brown-
ish orange solution. The toluene was filtered off via cannula,
the orange residue was washed with 20 mL of pentane, 80 mL
of methylene chloride was added, and this solution was filtered
over Celite under argon through a Schlenk frit. The Celite was
washed with 60 mL of methylene chloride. The volume of the
golden orange filtrate was reduced to one-fourth, during which
time a yellow precipitate was produced. The cloudy solution
was filtered via cannula but became cloudy after 5 min of
standing again. The cloudy solution was stored at room
temperature until the yellow precipitate settled to the bottom
of the Schlenk tube and a layer of pentane (50 mL) was applied
on the clear orange solution. After 7 days of standing at room
2-(3,5-Di-ter t-bu tyl-4-m eth oxyp h en yl)in d en e (4). Sub-
strate: Methyl 3,5-di-tert-butyl-4-methoxybenzoate, 2.245 g
(8.06 mmol). Flash chromatography on silica gel with hexanes.
1
Yield: 2.346 g of white oil (7.01 mmol, 87%). H NMR (CD2-
Cl2): δ 1.47 (s, 18H), 3.71 (s, 3H), 3.79 (s, 2H), 7.14 (s, 1H),
7.15 (td, J ) 7.0 Hz, J ) 0.8 Hz), 1H), 7.25 (t, J ) 7.5 Hz, 1H),
7.37 (d, J ) 7.5 Hz, 1H), 7.62 (d, J ) 7.5 Hz, 1H), 7.54 (s, 2H).
13C NMR (CD2Cl2): δ 32.18, 36.09, 39.47, 64.65, 120.88, 123.89,
124.41, 124.68, 125.36, 126.87, 130.67, 143.53, 144.24, 146.05,
147.55, 159.94.
2-(1-Ad a m a n ta n yl)in d en e (6). Substrate: Methyl 1-ada-
mantanylcarboxylate, 1.603 g (8.25 mmol). In contrast to the
general procedure, after the removal of the THF the reaction
mixture was not extracted with methylene chloride but with
diethyl ether. After drying with magnesium sulfate, the ether
was removed in vacuo. Toluene and 0.300 g (1.5 mmol) of
p-toluenesulfonic acid were added, and the mixture was heated
to 110 °C for 120 min with a Dean-Stark trap to remove the
produced water. After it was cooled to room temperature, the
reaction mixture was washed with water, the separated

4154 Organometallics, Vol. 18, No. 20, 1999
Witte et al.
Ta ble 5. Su m m a r y of Cr ysta llogr a p h ic Da ta a n d
P a r a m eter s for C34H32N2Cl2Zr
temperature, orange, needlelike crystals grew from the glass
wall into the solution at the original phase border. Unfortu-
nately we were not able to isolate these crystals without some
yellow solid on their surface. Yield: 153 mg orange crystals
with yellow impurities. Orange crystals were identified as M3
by X-ray. The mixture of the orange crystals and the yellow
solid was identified by 1H NMR as M3 containing the free
ligand 3 in a ratio of 0.415 mol of ligand/mol of M3. To 110
mg of the isolated material in a Schlenk tube with a small
magnetic stirrbar under argon was added 20 mL of toluene,
and the mixture was stirred for 10 min. The solution was
filtered off, and again 20 mL of toluene was added. After a
second stirring period of 5 min, the solution was filtered off
again and the remaining crystals were dried in vacuo. Yield:
64 mg (0.101 mmol, 10%) of orange crystals. 1H NMR
(CDCl3): δ 3.07 (s, 12H), 6.53 (s, 4H), 6.77 (d br, J ) 8 Hz,
4H), 7.04-7.07 (m, 4H), 7.12-7.14 (m, 4H), 7.42-7.46 (m, 4H).
13C NMR (CDCl3): δ 40.35, 102.02, 112.11, 121.10, 124.68,
formula
C34H32N2Cl2Zr
fw
630.77
temp (K)
space group
cell constantsa,b
a (Å)
178
I/2a (No. 15); monoclinic
22.6416(6)
6.8214(1)
b (Å)
c (Å)
18.9410(5)
90.000(1)
104.175(1)
90.000(1)
R (deg)
â (deg)
γ (deg)
V (Å3)
2836.3(1)
Z
4
0.01
1296.00
1.48
abs coeff, µcalcd (cm-3
F000
)
dcalcdc (g cm-3
)
cryst size (mm)
radiation (λ, Å)
monochromator
diffractometer
rflns measd
0.32 × 0.16 × 0.05
Mo KR (0.710 69)
highly oriented graphite
Siemens SMART
0 e h e 26, -7 e k e 7,
-22 e l e 20
2.52 e 2θ e 49.40
ω
126.05, 126.47, 127.94, 133.78, 150.53. Anal. Calcd for C34H32
-
Cl2N2Zr: C, 64.74; H, 5.11. Found: C, 64.55; H, 5.43.
Bis[2-(3,5-ter t-b u t yl-4-m et h oxyp h en yl)in d en yl]zir co-
n iu m Dich lor id e (M4). Ligand: 2-(3,5-tert-butyl-4-methox-
yphenyl)indene, 655 mg (1.96 mmol). Yield: 293 mg (0.353
2θ range (deg)
scan type
scan width (deg)
scan speed
1
mmol, 36%), yellow solid. H NMR (CD2Cl2): δ 1.56 (s, 36H),
0.3
3.82 (s, 6H),), 6.64-6.68 (m, 4H), 6.72 (s, 4H), 6.98-7.01 (m,
4H), 7.63 (s, 4H). 13C NMR (CD2Cl2): δ 32.16, 36.13, 64.67,
104.50, 124.32, 125.48, 126.11, 126.40, 127.03, 129.51, 144.65,
160.45. Anal. Calcd for C48H58Cl2O2Zr: C, 69.54; H, 7.05.
Found: C, 69.41; H, 7.24.
10 s frame exposure
6542
no. of rflns collected
no. of unique rflns
no. of rflns with Fo > 3σ(Fo
no. of variables
2600 (Rint ) 0.042)
2
2
)
1703
177
param to variable ratio
9:62
0.031 (0.037)
+0.39; -0.38
Bis(2-fer r ocen ylin d en yl)zir con iu m Dich lor id e (M5).
Ligand: 2-ferrocenylindene, 1.014 g (3.38 mmol). After the
toluene was removed in vacuo, 80 mL of methylene chloride
was added and the solution filtered over Celite under argon
through a Schlenk frit. The Celite was washed with an
additional 20 mL of methylene chloride. All liquid of the filtrate
was removed in vacuo, leaving a reddish brown solid, which
was a 2:1 mixture of complex to ligand according to the 1H
NMR spectrum. To this solid was added 40 mL of methylene
chloride, and the solution was filtered via cannula. The filtered,
dark red solution was layered with diethyl ether and stored
at -45 °C for 2 weeks. The liquid over the dark red-brown
precipitate was filtered off and added to the remaining solid
from the first filtration. The precipitate was dried in vacuo
overnight: 353 mg of dark red-brown solid, identified as M5
and containing 0.560 mol of methylene chloride/mol of M5 and
0.275 mol of diethyl ether/mol of M5 according to 1H NMR
(25% yield with regard to the amount of included solvents).
The liquid from the filtrate was removed in vacuo, 50 mL of
methylene chloride was added, the solution was filtered via
cannula, and the filtered solution was layered with 50 mL of
toluene and stored at -45 °C for 6 weeks. The remaining solid
from the filtration was washed with pentane and dried in
vacuo overnight. This solid (reddish brown), yield 88 mg (0.109
mmol, 6.5% with regard to the solvent content), was identified
R (Rw)d
e
final diff Fmax (e Å-3
)
a
Unit cell parameters and their esd’s were derived by a least-
squares fitting of 3494 reflections with I > 10σ(I) and 2θ between
b
2.52 and 49.40°. The esd’s of all parameters are given in
parentheses. c The density of the crystal was not measured. The
d
unweighted and weighted agreement factors in the least-squares
refinements were R ) ∑||Fo| - |Fc||/∑|Fo| and Rw ) [∑w([|Fo| -
2
|Fc|)2/∑wFo
]
1/2, where w ) 4Fo2/s2(Fo2), s2(Fo2) ) S2(C + R2B) +
(pFo2)2/Lp2, S ) scan rate, C ) total integrated peak count, R )
ratio of scan time to background counting time, B ) total
background count, Lp ) Lorentz-polarization factor, and p ) p
factor (0.03). e Maximum negative and positive difference peaks.
7.23 (m, 4H). 13C NMR (CDCl3): δ 28.56, 36.69, 36.75, 41.80,
101.64, 125.89, 126.60, 156.37. Anal. Calcd for C38H42Cl2Zr:
C, 69.06; H, 6.41. Found: C, 68.73; H, 6.20.
P olym er iza t ion s. Toluene and liquid propylene were
passed over towers containing Q5 and alumina prior to use.
Methylaluminoxane (MAO type 4) was obtained from Akzo
Nobel as a toluene solution and was dried in vacuo to give a
white solid before use. Polymerizations were carried out in a
300 mL Parr reactor equipped with a mechanical stirrer. The
temperature was maintained with an inside ethylene glycol/
water cooling loop (20 °C) and additional outside ice/water bath
(0 °C) or an aluminum heating block (40 °C). The reactor
bottom was baked in an oven (100 °C) for at least 1 h and
assembled while still hot. After evacuation to 30 mTorr and
purging with argon three times, leaving the reactor under a
argon pressure of 10 psi, liquid propylene (100 mL) was
introduced into the reactor and equilibrated to the designated
temperature. Catalyst solutions were prepared in the N2
drybox by dissolving 1000 equiv of MAO (294 mg for 5 × 10-6
mol of metallocene) in toluene. An aliquot of a metallocene
solution in toluene was added so that the total volume was 25
mL. The activated catalyst solution was injected under argon
pressure. The polymerization was allowed to proceed for 10-
60 min and then quenched with 15 mL of methanol injected
under argon pressure.
1
by H NMR to contain 0.585 mol of methylene chloride/mol of
metallocene.48 1H NMR (CDCl3): δ 3.95 (s, 10H),), 4.41 (t, J )
2.0 Hz, 4H), 4.55 (t, J ) 2.0 Hz, 4H), 3.82 (s, 6H), 6.27 (s, 4H),
7.07-7.11 (m, 4H), 7.20-7.23 (m, 4H). 13C NMR (CDCl3): δ
67.31, 69.62, 69.71, 78.82, 102.87, 124.67, 126.02, 126.05,
133.44. HRMS: m/z calcd 763.9506, 762.9520, 761.9487,
760.9474, 759.9473, 758.9504, 757.9470; found 763.9498,
762.9504, 761.9489, 760.9485, 759.9472, 758.9516, 757.9470.
Bis[2-(1-adam an tyl)in den yl]zir con iu m Dich lor ide (M6).
Ligand: 2-(1-adamantyl)indene, 375 mg (1.5 mmol). Yield: 144
mg (0.22 mmol, 29%) of yellow crystals. A second crop was
not obtainable because the mother liquor decomposed after the
crystals were filtered off. 1H NMR (CDCl3): δ 1.56-1.66 (m
br, 24H), 1.90 (s br, 6H), 5.86 (s, 4H), 7.18-7.22 (m, 4H), 7.69-
The polymers were collected and precipitated into acidified
methanol (5% HCl). After being stirred overnight, the polymers
were dried in a vacuum oven at 40 °C.
(48) Because the remaining solvent in the isolated solid could not
be removed in vacuo, elemental analyses were off in carbon about 3%.

Unbridged Bis(2-R-indenyl)zirconocenes
Organometallics, Vol. 18, No. 20, 1999 4155
X-r a y Diffr a ction Stu d y. Bis[2-(4-(d im eth yla m in o)-
p h en yl)in d en yl]zir con iu m Dich lor id e (M3). A crystal of
atoms. All calculations were performed using the teXsan52
crystallographic software package of Molecular Structure Corp.
Crystal data and details of data collection and structure
analysis are summarized in Table 5.
C
34H32N2Cl2Zr with approximate dimensions 0.32 × 0.16 ×
0.05 mm3 grown from a solution of dichloromethane/pentane
was mounted on a glass fiber in Paratone oil at -80 °C using
an improvised cold stage. All measurements were made on a
Siemens SMART49 diffractometer with graphite-monochro-
mated Mo KR radiation. The structure was solved by direct
methods50 and expanded using Fourier techniques.51 All non-
hydrogen atoms were refined anisotropically. Hydrogen atoms
were included at idealized positions, 0.95 Å from their parent
Ack n ow led gm en t. Financial support from Amoco
Chemical and the DAAD is gratefully acknowledged. We
thank J ennifer Petoff, Shirley Lin, Dr. Michael S.
Driver, and Dr. Udo Stehling for helpful discussions.
We thank Amoco Chemical Co. for GPC analyses.
Su p p or tin g In for m a tion Ava ila ble: Tables and figures
giving additional information on the X-ray crystallographic
determination of M3. This material is available free of charge
via the Internet at http://pubs.acs.org.
(49) SMART: Area-Detector Software Package; Siemens Industrial
Automation, Inc., Madison, WI, 1995.
(50) Sheldrick, G. SHELXS-86, 1986.
(51) DIRDIF92: Beurskens, P. T.; Admiraal, G.; Beurskens, G.;
Bosman, W. P.; Garcia-Granda, S.; Gould, R. O.; Smits, J . M. M.;
Smykalla, C. The DIRDIF program system; Technical Report of the
Crystallography Laboratory; University of Nijmegen, The Netherlands,
1992.
OM990083W
(52) teXsan: Crystal Structure Analysis Package; Molecular Struc-
ture Corp., The Woodlands, TX, 1985, 1992.