Mixed ligand metallocenes as catalysts for elastomeric polypropylene

Article abstract of DOI:10.1021/om9807957

A new synthesis of unbridged mixed ring zirconocenes was developed and a series of mixed ligand zirconocenes with substituted 2-arylindenyl and 1-methyl-2-arylindenyl ligands have been prepared. When activated with methylaluminoxane, the mixed ligand complexes catalyze the polymerization of propylene to give elastomeric polypropylene. The propylene polymerization behavior of the mixed ligand catalysts was compared to that of their bis-(indenyl) analogues to determine the relative contribution of each ligand to the activity and stereospecificity of the catalyst. The effects of 2-arylindenyl and 1-methyl-2-arylindenyl ligands on the stereospecificity of the catalysts are essentially additive; the stereospecificity of the mixed ring complex is intermediate to that of the bis(2-arylindene) analogues. However, the effect of 1-methyl substitution on catalyst productivity is not additive; the productivities exhibited by bis(2-arylindenyl)ZrCl₂/MAO and (1-methyl-2-arylindenyl)(2-arylindenyl)ZrCl₂/ MAO derived catalysts are similar and substantially higher than those of the bis(1-methyl-2-phenylindenyl)ZrCl₂/MAO catalysts.

Full text of DOI:10.1021/om9807957

380
Organometallics 1999, 18, 380-388
Mixed Liga n d Meta llocen es a s Ca ta lysts for Ela stom er ic
P olyp r op ylen e
Christopher D. Tagge, Raisa L. Kravchenko, Tappan K. Lal, and
Robert M. Waymouth*
Department of Chemistry, Stanford University, Stanford, California 94305
Received September 22, 1998
A new synthesis of unbridged mixed ring zirconocenes was developed and a series of mixed
ligand zirconocenes with substituted 2-arylindenyl and 1-methyl-2-arylindenyl ligands have
been prepared. When activated with methylaluminoxane, the mixed ligand complexes
catalyze the polymerization of propylene to give elastomeric polypropylene. The propylene
polymerization behavior of the mixed ligand catalysts was compared to that of their bis-
(indenyl) analogues to determine the relative contribution of each ligand to the activity and
stereospecificity of the catalyst. The effects of 2-arylindenyl and 1-methyl-2-arylindenyl
ligands on the stereospecificity of the catalysts are essentially additive; the stereospecificity
of the mixed ring complex is intermediate to that of the bis(2-arylindene) analogues. However,
the effect of 1-methyl substitution on catalyst productivity is not additive; the productivities
exhibited by bis(2-arylindenyl)ZrCl2/MAO and (1-methyl-2-arylindenyl)(2-arylindenyl)ZrCl2/
MAO derived catalysts are similar and substantially higher than those of the bis(1-methyl-
2-phenylindenyl)ZrCl2/MAO catalysts.
In tr od u ction
Furthermore, Chien and Collins have shown that ho-
mogeneous catalysts with well-defined structures are
also capable of producing elastomeric polypropylene.19-25
Recently, our group reported a new strategy for
producing elastomeric polypropylene.26-31 The approach
is based on a fluxional bis(2-arylindenyl)zirconium
homogeneous catalyst system that can isomerize be-
tween stereospecific chiral and aspecific achiral geom-
etries during the course of the polymerization (Scheme
1). Investigations of these systems have shown that the
Natta’s discovery of thermoplastic elastomeric polypro-
pylene in the late 1950s1 prompted both industrial and
academic interest in producing and studying this mate-
rial. To explain the intriguing elastomeric properties,
Natta proposed that the material had a stereoblock
microstructure, consisting of alternating segments of
isotactic and atactic sequences, which resulted from a
dynamic mechanism in which the catalyst active site
altered its stereospecificity several times during the
formation of the polymer chain.2 Unfortunately, the
heterogeneous nature of the catalysts frustrated efforts
to investigate the mechanism and optimize these po-
lymerization reactions. Nevertheless, a number of in-
dustrial efforts have made substantial progress for the
synthesis of elastomeric polypropylenes with a wide
range of structures and mechanical properties.3-18
(15) Pellon, B. J .; Allen, G. C. (Rexene) Eur. Pat. Appl. 0 475 306
A1, 1992.
(16) Schrage, A. (Rexall) US Patent 3,329,741, 1967.
(17) Smith, C. A. (Himont) Eur. Pat. Appl. 423786 A2, 1991.
(18) Tullock, C. W.; Mulhaupt, R.; Ittel, S. D. Makromol. Chem.,
Rapid Commun. 1989, 10, 19-23.
(19) Mallin, D. T.; Rausch, M. D.; Lin, Y. G.; Dong, S.; Chien, J . C.
W. J . Am. Chem. Soc. 1990, 112, 2030-2031.
(20) Chien, J . C. W.; Llinas, G. H.; Rausch, M. D.; Lin, Y. G.; Winter,
H. H.; Atwood, J . L.; Bott, S. G. J . Polym. Sci. Part A: Polym. Chem.
1992, 30, 2601-2617.
(1) Natta, G.; Mazzanti, G.; Crespi, G.; Moraglio, G. Chim. Ind.
(Milan) 1957, 39, 275-283.
(2) Natta, G. J . Polym. Sci. 1959, 34, 531-549.
(3) Tullock, C. W.; Tebbe, F. N.; Mulhaupt, R.; Ovenall, D. W.;
Setterquist, R. A.; Ittel, S. D. J . Polym. Sci., Part A: Polym. Chem.
1989, 27, 3063-3081.
(4) Arnold, M.; Schmidt, V.; Frank, W. Plaste Kautsch. 1991, 38,
73-77.
(5) Collette, J . W.; Tullock, C. W. (E. I. du Pont de Nemours) U.S.
Pat. 4,298,722, 1981.
(6) Collette, J . W.; Tullock, C. W. (E. I. du Pont de Nemours) U.S.
Pat. 4,335,225, 1982.
(7) Collette, J . W.; Tullock, C. W.; MacDonald, R. N.; Buck, W. H.;
Su, A. C. L.; Harrell, J . R.; Mulhaupt, R.; Anderson, B. C. Macromol-
ecules 1989, 22, 3851-3858.
(8) Collette, J . W.; Ovenall, D. W.; Buck, W. H.; Ferguson, R. C.
Macromolecules 1989, 22, 3858-3866.
(9) Gobran, R. (3M) U.S. Patent 3,784,502, 1974.
(10) J ob, R. C. (Shell Oil Co.) U.S. Patent 5,118,649, 1992.
(11) J ob, R. C. (Shell Oil Co.) U.S. Patent 5,118,767, 1992.
(12) Kontos, E. G. US Patent 3,378,606, 1968.
(13) Kontos, E. G. U.S. Patent 3,853,969, 1974.
(14) Pellon, B. J .; Allen, G. C. (Rexene) Eur. Pat. Appl. 0 475 307
A1, 1992.
(21) Chien, J . C. W.; Llinas, G. H.; Rausch, M. D.; Lin, G. Y.; Winter,
H. H.; Atwood, J . L.; Bott, S. G. J . Am. Chem. Soc. 1991, 113, 8569-
70.
(22) Chien, J . C. W.; Rieger, B.; Sugimoto, R.; Mallin, D. T.; Rausch,
M. D. Stud. Surf. Sci. Catal. 1990, 56, 535-574.
(23) Gauthier, W. J .; Collins, S. Macromolecules 1995, 28, 3779-
3786.
(24) Gauthier, W. J .; Corrigan, J . F.; Taylor, N. J .; Collins, S.
Macromolecules 1995, 28, 3771-3778.
(25) Bravakis, A. M.; Bailey, L. E.; Pigeon, M.; Collins, S. Macro-
molecules 1998, 31, 1000-1009.
(26) Coates, G. W.; Waymouth, R. M. Science 1995, 267, 217-219.
(27) Hauptman, E.; Waymouth, R. M.; Ziller, J . W. J . Am. Chem.
Soc. 1995, 117, 11586-11587.
(28) Bruce, M. D.; Coates, G. W.; Hauptman, E. H.; Waymouth, R.
M.; Ziller, J . W. J . Am. Chem. Soc. 1997, 119, 11174-11182.
(29) Maciejewski-Petoff, J . L.; Bruce, M. D.; Waymouth, R. M.;
Masood, A.; Lal, T. K.; Quan, R. W.; Behrend, S. J . Organometallics
1998, 16, 55909-5916.
(30) Kravchenko, R.; Masood, A.; Waymouth, R. M. Organometallics
1997, 16, 3635-3639.
(31) Kravchenko, R. L.; Masood, M.; Waymouth, R. M.; Myers, C.
L. J . Am. Chem. Soc. 1998, 120, 2039-2046.
10.1021/om9807957 CCC: $18.00 © 1999 American Chemical Society
Publication on Web 12/31/1998

Mixed Ligand Metallocenes as Catalysts
Organometallics, Vol. 18, No. 3, 1999 381
Sch em e 1. P r op osed Mech a n ism for F or m a tion of
Ela stom er ic P olyp r op ylen e
solvents. However, the tribromide complexes 3b and 4b
exhibit sharp H NMR resonances, which are consistent
1
with a monomeric structure. Thus, relatively soluble
tribromides 3b and 4b were recrystallized from toluene
in good yield, while trichloride 3a and 4a could only be
purified by successive diethyl ether, toluene, and pen-
tane washes and were isolated in lower yields.
NMR analysis of 4 revealed residual signals from Me3-
Si and NMe2-containing impurities which could not be
removed by recrystallization. Nevertheless, the impuri-
ties did not have a detrimental effect on the subsequent
transformations of 4, and the complexes were used
without further purification.
productivity and stereospecificity of the catalysts (and
thus, the physical and mechanical properties of the
resulting polymers) can be significantly influenced by
utilizing different substituents in the 1- and 3′,5′-
positions of the 2-phenylindenyl ligand.27,30 To further
investigate the effects of ligand substituents on catalyst
behavior and produce a family of catalysts capable of
accessing a broader range of polypropylene structures,
we now report a new route to unbridged mixed ring
zirconocenes and describe the polymerization behavior
of mixed ring 2-arylindenyl zirconocenes.
Mixed ring zirconocene dihalide complexes were easily
prepared by reaction of half-sandwich zirconium triha-
lides 3 and 4 with the corresponding lithium 2-arylin-
denide in toluene. When optimized, the mixed ring
complexes were obtained in good yield (50-80%). To
identify the effect of the halogen ligands, bis(indenyl)
complexes (2PhInd)2ZrBr2 (5b) (2PhInd ) 2-phenylin-
denyl) and (BArf)2ZrBr2 (10b ) (BArf ) 2-(3′,5′-bistri-
fluoromethylphenyl)indenyl) were prepared from the
half-sandwich tribromides 3b and 4b, respectively. The
preparation of dichloride analogues 5a and 10a has been
previously described.26,27
Resu lts
All previously characterized bis(2-arylindenyl)zirco-
Syn th esis of Mixed Liga n d Bis(2-a r ylin d en yl)-
zir con iu m Com p lexes. The reaction of 2-arylindenes
with zirconium tetrakis(dimethylamide) eliminates 1
equiv of dimethylamine to produce 2-arylindenylzirco-
nium tris(dimethylamide) (1 and 2) (eq 1).32 The com-
plexes may be isolated by crystallization from hexane
or used without purification. Reaction of 1 or 2 with 3
equiv of trimethylsilylhalide in methylene chloride
results in the elimination of trimethylsilyl(dimethyl)-
amide and the formation of the corresponding 2-aryl-
indenylzirconium trihalide (3 and 4) (eq 2).33,34
nium dichloride precatalysts exhibit C2v symmetry in
solution (as judged by H NMR spectroscopy), which is
1
consistent with rapid rotation of the indenyl ligands.26-29
Similarly, 3′,5′-substituted mixed ligand catalysts ex-
hibited Cs symmetry in solution, and the ring rotation
could not be substantially slowed even at low temper-
atures (-80 °C). Introduction of a 1-Me substituent on
one of the ligands further decreased the symmetry of
complexes 8,9 and 12,13 to C1 and made the two
cyclopentadienyl-type protons on the second ligand
diastereotopic. A characteristic doublet-doublet-singlet
(J ≈ 2.5 Hz) pattern in the cyclopentadienyl proton
region was observed for the 1-Me-substituted mixed
ligand complexes.
In general, the chemical shifts of the cyclopentadienyl
protons of the mixed ligand complexes fell between those
of the parent bis(indenyl) complexes. This was particu-
larly evident for ligands having substantially different
electronic properties and chemical shifts. For example,
the chemical shift of the cyclopentadienyl protons of
(2PhInd)2ZrCl2 (5a ) and (BArf)2ZrCl2 (10a ) appear at δ
6.41 and 5.69, respectively. The corresponding reso-
nances of mixed ring complex 6a appear at δ 6.23 and
5.87; thus, the cyclopentadienyl protons of the 2-PhInd
and BArf ligands are shifted 0.18 ppm upfield and 0.18
downfield, respectively, from their analogous resonances
of 5a and 10a .
The identity of the halide substituent appears to
influence the properties of half-sandwich complexes 3
and 4 in solution. The trichloride complexes 3a and 4a
appear to exist primarily as oligomers as indicated by
broad NMR resonances and low solubilities in most
Dimethyl-substituted 7 has been characterized by X-
ray diffraction (Figure 1). Unlike 5a , in which both the
syn- and anti-rotamers are present in the asymmetric
unit cell,26 7 adopts only the syn-like structure in the
solid state, similar to that observed for (DMPInd)2ZrCl2
(14) (DMPInd ) 2-(3′,5′-dimethylphenyl)indenyl).27 Aside
from the difference in halogen bond lengths, mixed
ligand 7 is essentially isostructural to the syn-rotamer
of both 5a and 14. For example, the dihedral angles
between the phenyl and indenyl rings of 7 are 13° for
(32) Chandra, G.; Lappert, M. F. J . Chem. Soc. (A) 1968, 1940-
1945.
(33) J ordan, R. F.; Diamond, G. M.; Christopher, J . N.; Kim, I.
Polym. Prepr. 1996, 37, 256.
(34) Carpenetti, D. W.; Kloppenburg, L.; Kupec, J .; Peterson, J . L.
Organometallics 1996, 15, 1572-1581.

382 Organometallics, Vol. 18, No. 3, 1999
Tagge et al.
analogue 14/MAO ([mmmm] ) 23%) (Table 1, entries
8,9, and 1,2, respectively).
The productivities and molecular weights of polymers
produced by 3′,5′-substituted mixed ligand catalysts
were similar to those generally observed for bis(2-
arylindenyl)zirconium catalysts. The productivities
ranged from 1140 kg/(mol Zr‚h) for 6b/MAO to 2180 kg/
(mol Zr‚h) for 11/MAO.
P olym er iza tion Stu d ies: Effect of 1-Me Su bsti-
tu tion . The productivity trends for 9,12,13/MAO were
consistent with our previous observation that 1-methyl
substitution lowers propylene polymerization productiv-
ity of catalysts of this type (Table 1, entries 6, 7, 11,
12).30 Surprisingly, the productivity of 2PhInd/
1Me2PhInd 8/MAO (1Me2PhInd ) 1-methyl-2-phenyl-
indenyl) was somewhat higher than that found for
unsubstituted bis(2-phenylindenyl)zirconium dichloride
5a /MAO. Isotactic pentad contents of mixed ligand
catalysts ranged from 14% for 8/MAO to 47% for 13/
MAO and fell into the limits set by their correspond-
ingbis(indenyl) analogues meso-(1Me2PhInd)2ZrCl2 (m e-
so-15)/MAO (11%) at the lower end and (BArf)2ZrCl2/
MAO (10a , 68%) at the higher end (Table 1, entries 14,
11,12, and 5,6). Molecular weights (from 217 000 to
293 000) and molecular weight distributions (Mw/Mn )
3-7) observed for 8,9, 12,13/MAO are also in the range
typically observed for unbridged bis(2-arylindenyl) cata-
lysts.
F igu r e 1. X-ray crystal structure of the mixed ring
indenylmetallocene 7.
Ph-Ind and 11° for DMP-Ind) compared to 10° and 12°
for syn-5a .
P olym er iza t ion St u d ies: E ffect of H a lid e Lig-
a n d s. The nature of the halogen atom of (2-ArInd)2ZrCl2
does not appear to influence the stereospecificity, mea-
sured by isotactic pentad content ([mmmm]), or produc-
tivities of the catalysts produced by reaction with MAO
(Table 1, entries 1-6). The stereospecificities of the
dichloride 10a /MAO ([mmmm] ) 67%) and the dibro-
mide 10b/MAO ([mmmm] ) 69%) are identical within
experimental error (ca. 2%). The productivities for the
dichloride and dibromide derivatives are also quite
similar, as both unsubstitued 5a and 5b/MAO showed
productivities of 2500 kg(mol Zr‚h). Catalysts derived
from trifluoromethyl-substituted 10a and 10b/MAO
differ only slightly, having productivities of 3000 and
2700 kg(mol Zr‚h), respectively. However, the molecular
weight distributions of the polymers produced by dichlo-
ride complexes 5a , 6a , and 10a /MAO are slightly
broader than those produced by the analogous dibro-
mide catalysts.
P olym er iza tion Stu d ies: 3′,5′-Su bstitu ted Mixed
Liga n d Com p lexes. All mixed ligand zirconocenes in
combination with MAO were active propylene polym-
erization catalysts (Table 1). The isotacticity of the
polymers produced by the 3′,5′-substituted mixed ligand
complexes ranged from 21% for DMPInd/2PhInd-ligated
7/MAO to 54% for DMPInd/BArf-substituted 11/MAO
(Table 1, entries 7, 8). In general, the isospecificities of
the mixed ligand catalysts fell between the extremes
defined by their respective bis(indenyl) analogues. This
behavior was particularly evident when the bis(indenyl)
complexes had widely different isospecificities. For
example, (DMPInd)2ZrCl2 (14)/MAO produces a polymer
with a relatively low isotacticity ([mmmm] ) 23%),
while (BArf)2ZrX2 (10)/MAO derived catalysts are highly
isospecific ([mmmm] ) 67-69%, Table 1, entries 9 and
5,6). The corresponding mixed ligand catalyst 11/MAO
shows an intermediate isospecificity of [mmmm] ) 54%
(Table 1, entry 7). Similarly, the isotacticity of polymers
produced by mixed ligand 6/MAO ([mmmm] ) 33-35%)
falls between those exhibited by its bis(indenyl) ana-
logues (2PhInd)2ZrX2 (5)/MAO ([mmmm] ) 28%) and
10/MAO ([mmmm] ) 67-69%) (Table 1, entries 1-6).
The single exception was dimethyl-substituted 7/MAO,
which produced a polymer having essentially the same
isotacticity ([mmmm] ) 21%) as that of its homo ligand
Discu ssion
Syn th esis. In general, L2ZrCl2 complexes (L ) cy-
clopentadienyl or indenyl-type ligand) are easily made
from the corresponding alkali cyclopentadienide or
indenide and zirconium tetrachloride. However, due to
the difficulties in preparing the intermediate half-
sandwhich zirconium complexes (LZrCl3), very few
mixed ring zirconocenes (L′L′′ZrCl2) have been prepared.
Apparently, the high reactivity of alkali cyclopentadi-
enides and trimethylsilylcyclopentadienes, combined
with the relative solubility of LZrCl3 compared to ZrCl4,
precludes single substitution for all but sterically de-
manding ligands.35-37 Alternatively, routes involving
free radical chlorination of commercially available Cp2-
ZrCl2 were needed to prepare CpZrCl3.38,39
Recently, Morris and co-workers reported that the
reaction of indenyltrialkyltin with ZrCl4 generated
IndZrCl3 in good yields.40 While we found that 3a could
be successfully produced by the tin-mediated synthesis,
we have found the following method to be much more
convenient and efficient to prepare 2-arylindenyl half-
sandwich complexes. The reaction of 2-arylindenes with
zirconium tetrakis(dimethylamide) allows the introduc-
tion of only a single ligand, presumably due to steric
constraints (eq 1).32 The half-sandwich trihalide complex
can then be prepared simply by the addition of 3 equiv
(35) Winter, C. H.; Zhou, X.-X.; Dobbs, D. A.; Heeg, M. J . Organo-
metallics 1991, 10, 210-214.
(36) Wolczanski, P. T.; Bercaw, J . E. Organometallics 1982, 1, 793-
799.
(37) Shafiq, F. A.; Richardson, D. E.; Boncella, J . M. J . Organomet.
Chem. 1998, 555, 1-4.
(38) Wells, N. J .; Huffman, J . C.; Caulton, K. G. J . Organomet.
Chem. 1981, 213, C17-C20.
(39) Erker, G. J . Organomet. Chem. 1990, 400, 185-203.
(40) Shaw, S. L.; Morris, R. J .; Huffman, J . C. J . Organomet. Chem.
1995, 489, C4-C6.

Mixed Ligand Metallocenes as Catalysts
Organometallics, Vol. 18, No. 3, 1999 383
Ta ble 1. P r op ylen e P olym er iza tion w ith F lu xion a l Hom ogen eou s Ca ta lysts (L1L2Zr X2)a
d
entry no.
catalyst
ligand 1
ligand 2
X
prodb
[mmmm]c
[m]c
Mw
MWD
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
5a
5b
6a
6b
10a
10b
11
7
14
12
13
8
2PhInd
2PhInd
2PhInd
2PhInd
BArf
BArf
BArf
2PhInd
DMPInd
BArf
2PhInd
2PhInd
BArf
BArf
BArf
Cl
Br
Cl
Br
Cl
Br
Br
Br
Cl
Cl
Cl
Cl
Cl
Cl
Cl
2480
2490
1440
1140
3000
2740
2180
1470
780
1810
1030
2800
1350
140
28
28
35
33
69
67
54
21
23
24
47
14
31
11
16
67
67
72
73
88
88
81
64
65
65
78
59
67
459
393
348
306
505
538
249
313
240
262
270
293
217
69
3.7
3.2
3.3
2.8
5.7
5.2
4.4
2.9
3.0
3.7
6.5
3.8
4.4
8.6
15.3
BArf
DMPInd
DMPInd
DMPInd
1Me2PInd
1MeBarf
1Me2PInd
1MeBarf
1Me2PInd
1Me2PInd
BArf
2PhInd
2PhInd
1Me2PInd
1Me2PInd
9
m eso-15
r a c-15
250
56
a
b
d
Polymerization conditions: 100 mL propylene/20 mL toluene, 20 °C, [Zr] ) 5 × 10-5 M, [Al]/[Zr] )1000. kg/(mol Zr‚h). c (%). (×
1000).
F igu r e 2. (a) Syn- and anti-rotamers of a 3′,5′-substituted mixed 2-arylindenyl catalyst. (b) Rotamers that result from
1-Me- and 3′,5′-substituted mixed 2-arylindenyl catalyst.
of the desired trimethylsilyl halide (eq 2).33,34 The half-
sandwich tribromides are more easily isolable due to
their enhanced solubility relative to the trichlorides.
Str u ctu r e. The proposed polymerization mechanism
by which the bis(2-arylindenyl) catalysts produce ster-
eoblock polypropylene involves an equilibrium between
the syn- and anti-rotameric forms of the active catalyst.
Rappe´ has calculated that π-stacking interactions be-
tween ligands stabilize both rotameric forms of bis(2-
arylindenyl)zirconium dichloride complexes in the solid
state.41 Favorable π-stacking interactions might be
anticipated to result from increased electrostatic attrac-
tions between the differently substituted phenyl rings
of mixed ring complexes 6, 7, and 11. However, the
chemical shifts in the solution NMR provide no evidence
for such intramolecular interactions in solution. Com-
plexes 6, 7, and 11 all exhibit C2v symmetry in solution
(consistent with rapid rotation of the indenyl ligands),
even at low temperatures (-80 °C). In the solid state,
mixed ligand complex 7 adopts a syn-like structure
similar to that observed for its homoleptic analogue 14.
P olym er iza tion Beh a vior : Effect of Ha lid e Lig-
a n d s. During the preparation of zirconium half-sand-
wich trihalides, we discovered that the half-sandwich
tribromides 3b and 4b could be isolated in higher yield
than analogous trichlorides 3a and 4b. Since much
recent work has shown that polymerization occurs at
the zirconium cationic species, the active site derived
from either halogen complex should be similar (eq 5).42
However, several researchers have noted that the
identity of the anion can have an effect on the properties
(including stereospecificity and productivity) of the
catalyst43-48 particularly for strongly coordinating an-
ions.49 Thus it is possible that the nature of anion might
influence the stereospecificity and activity of the cata-
lyst. To test for possible contributions from the bromide
ligands, we prepared bis(indenyl) dibromides 5b and
(41) Pietsch, M. A.; Rappe´, A. K. J . Am. Chem. Soc. 1996, 118,
10908-10909.
(42) J ordan, R. F. Adv. Organomet. Chem. 1991, 32, 325-387.

384 Organometallics, Vol. 18, No. 3, 1999
Tagge et al.
10b for comparison. We also prepared both dihalide
derivatives of mixed ligand 6. The identity of the
halogen atom did not affect the stereospecificity or
productivity of the catalysts.
mixed ligand complexes 8,9 and 12,13.30 Thus, a single
1-Me substituent does not significantly affect the be-
havior of the catalyst.
P olym er iza tion Stu d ies: Mixed Liga n d Com -
p lexes. Fluxional 2-arylindenyl catalysts were designed
to interconvert between the achiral, aspecific syn and
chiral, isospecific anti geometries during the formation
of a polymer chain to produce a stereoblock structure
(Scheme 1). The overall similarity of the resulting
polymer properties suggests that the mixed and homo
ligand 2-arylindenyl catalysts operate by a similar
mechanism (Figure 2a). We have shown that the iso-
specificity of bis(2-arylindenyl) catalysts is strongly
dependent on the nature of the 3′,5′-substituents.27 We
now find that mixed ligand complexes have an isospec-
ificity intermediate to that of their bis(indenyl) ana-
logues. However, the isospecificity of the mixed ligand
complex is not the weighted average of the homoleptic
congeners. For example, BArf/DMPInd-ligated 11 has
a much higher isospecificity ([mmmm] ) 54%) than
BArf/2PhInd-substituted 6/MAO ([mmmm] ) 33-
35%), despite the fact that bis(indenyl) complexes
(DMPInd)2ZrCl2 (11/MAO) and (2PhInd)2ZrCl2 (5/MAO)
are quite similar ([mmmm] ) 23 and 28, respectively).
This may be indicative of some subtle steric or electronic
effects between ligands for the 2-arylindenyl catalysts.
Nevertheless, as the properties of the mixed ring
complexes consistently fall between those of their bis-
(indenyl) analogues, we conclude that the effects of each
ligand on the attributes of the catalysts are primarily
additive.
1-Substituted 8,9 and 12,13 are completely devoid of
symmetry elements, which leads to a greater number
of possible rotamers and thus further complicates the
interpretation of the behavior of these catalysts (Figure
2b). Furthermore, the 1-Me substituent is very close to
the active site and should thus have a much larger steric
influence on the behavior of the catalyst than the
relatively distant 3′,5′-substituents. Nevertheless, as
was observed for 3′,5′-substitution, the stereospecificities
and polymer molecular weights and molecular weight
distributions of the 1-Me-substituted mixed ring cata-
lysts consistently fall between the two extremes set by
their bis(indenyl) analogues. However, the contributions
of 1-Me-substituted ligands on the productivities and
molecular weights of mixed ring complexes are not
strictly additive. For example, the productivities and
molecular weights of both r a c- and m eso-15 are an
order of magnitude lower and the molecular weight
distributions much higher (indicating decreased rate of
rotamer interconversion) than those of bis(2-arylinde-
nyl) catalysts without 1-Me substituents as well as
Con clu sion s
We have developed a new and convenient route to
generate mixed ligand zirconium complexes and have
examined the polymerization behavior of several flux-
ional, mixed ligand 2-arylindenyl complexes having
substituents in the 1- and/or 3′,5′-positions. While the
effects of the substituents on the dynamic behavior are
complex, it is clear that the mixed ligand catalysts
generally have properties intermediate to those ob-
served for their bis(indenyl) analogues.
Exp er im en ta l Section
Gen er a l Con sid er a tion s. All organometallic reactions
were conducted using standard Schlenk and drybox tech-
niques. Elemental analyses were performed by E&R Mi-
croanalytical Laboratory and Desert Analytics. Unless other-
wise specified all reagents were purchased from commercial
suppliers and used without further purification. 1-Methyl-2-
phenylindene, 2-(3′,5′-bis(trifluoromethyl)phenyl)indene, 2-(3′,5′-
dimethylphenyl)indene, bis(2-phenylindenyl)zirconium dichlo-
ride (5a ), bis((3′,5′-bistrifluoromethylphenyl)indenyl)zirconium
dichloride (10a ), and rac-bis(1-methyl-2-phenylindenyl)zirco-
nium dichloride were prepared according to literature proce-
dures.27,28,30 Hexane, pentane, and methylene chloride were
distilled from calcium hydride under nitrogen. Tetrahydrofu-
ran was distilled from sodium/benzophenone under nitrogen.
Toluene was passed through two purification columns packed
with activated alumina and supported copper catalyst and
collected under argon. Methylene dichloride-d2 and chloroform-
d3 were vacuum transferred from calcium hydride. Benzene-
d6 was vacuum transferred from sodium/benzophenone.
(2-(3′,5′-Bis(t r iflu or om e t h yl)p h e n yl)in d e n yl)zir co-
n iu m Tr is(d im eth yla m id e) (2). A 250 mL Schlenk flask was
charged with 2-(3′,5′-bis(trifluoromethyl)phenyl)indene (0.356
g, 1.08 mmol), zirconium tetrakis(dimethylamide) (0.283 g,
1.07 mmol), and toluene (25 mL). The yellow mixture was
stirred at room temperature for 100 min and then evaporated
to dryness. The off-white residue was dissolved in hexane (25
mL) and filtered by cannula. The yellow solution was concen-
trated to a volume of 10 mL and stored at -20 °C for 16 h and
then -50 °C for 2 days. Decantation of the solvent by cannula
and drying in vacuo afforded 2-(3′,5′-bis(trifluromethyl)phe-
nyl)indenylzirconium tris(dimethylamide) as yellow crystals
(0.477 g, 81%). 1H NMR (C6D6, 400 MHz, 296 K): δ 2.50 (s, 18
H), 6.14 (s, 2 H), 6.92 (dd, 2 H), 7.45 (dd, 2 H), 7.67 (s, 1 H),
7.91 (s, 2 H).
2-P h en ylin d en ylzir con iu m Tr ich lor id e (3a ). A 100 mL
Schlenk tube was charged with 2-phenylindene (0.460 g, 2.40
mmol), zirconium tetrakis(dimethylamide) (0.506 g, 1.89 mmol),
and toluene (15 mL). The yellow solution was stirred for 3 h
at room temperature and then evaporated to dryness. The
residue was extracted with hexane (10 mL), filtered by
cannula, and then evaporated to dryness to give (2-PhInd)Zr-
(NMe2)3 (1). The residue was dissolved in methylene chloride
(10 mL), and the light yellow solution was cooled to 0 °C.
Chlorotrimethylsilane (0.80 mL, 6.3 mmol) was added by
syringe. The solution immediately became colorless and then
gradually turned bright yellow. The solution was warmed to
20 °C, stirred for 1 h, and then evaporated to dryness. The
orange foam was dissolved in toluene (20 mL) and stirred.
Within 10 min a bright yellow powder began to precipitate.
The slurry was stirred for 12 h, and the mixture was filtered
by cannula. The bright yellow powder was washed with toluene
(43) Chien, J . C. W.; Song, W.; Rausch, M. D. Macromolecules 1993,
26, 3239-3240.
(44) Eisch, J . J .; Pombrik, S. I.; Zheng, G.-X. Organometallics 1993,
12, 3856-3863.
(45) J ia, L.; Yang, X.; Ishihara, A.; Marks, T. J . Organometallics
1995, 14, 3135-3137.
(46) J ia, L.; Yang, X.; Stern, C.; Marks, T. J . Organometallics 1997,
16, 842-857.
(47) Naga, N.; Mizunuma, K. Marcomol. Rapid Commun. 1997, 18,
581-589.
(48) Yang, X.; Stern, C. L.; Marks, T. J . J . Am. Chem. Soc. 1994,
116, 10015-10031.
(49) Chen, Y.-X.; Metz, M. V.; Li, L.; Stern, C. L.; Marks, T. J . J .
Am. Chem. Soc. 1998, 120, 6287-6305.
1
(5 mL) and dried in vacuo (two crops, 0.137 g, 41%). H NMR

Mixed Ligand Metallocenes as Catalysts
Organometallics, Vol. 18, No. 3, 1999 385
(C6D6, sparingly soluble, 400 MHz, 296 K): δ 6.60 (s, 2 H),
6.90 (dd, J ) 3, 3 Hz, 2 H), 7.06 (d, J ) 7 Hz, 1 H), 7.12
(obscured), 7.22 (dd, J ) 3, 3 Hz, 2 H), 7.51 (d, J ) 7 Hz, 2 H).
1H NMR (CD2Cl2, 400 MHz, 296 K), a mixture of monomer
and oligomers: δ 6.87 (sharp s, 2 H), 7.19 (sharp dd), 7.30
(broad s), 7.40 (broad m), 7.46 (broad m), 7.60 (sharp dd), 7.70-
7.90 (broad m). Anal. Calcd for C15H11Cl3Zr: C, 46.34; H, 2.85.
Found: C, 46.00; H, 2.82.
2-P h en ylin d en ylzir con iu m Tr ibr om id e (3b). A 250 mL
Schlenk flask was charged with 2-phenylindene (0.700 g, 3.59
mmol), zirconium tetrakis(dimethylamide) (0.930 g, 3.51 mmol),
and ether (100 mL). The yellow solution was stirred for 16 h
at room temperature and then evaporated to dryness to give
(2-PhInd)Zr(NMe2)3 (1). Powdery 1 was dissolved in toluene
(120 mL), and bromotrimethylsilane (1.6 mL, 12 mmol) was
added by syringe. The yellow solution was stirred for 16 h.
An orange precipitate had formed. The mixture was stirred
for an additional 20 h. The yellow solution was filtered by
cannula into a 500 mL Schlenk flask, concentrated to a volume
of 100 mL, and stored at -20 °C for 2 days to afford (2-PhInd)-
ZrBr3‚0.3 toluene (3b) as yellow blocks (two crops, 1.51 g, 78%).
1H NMR (C6D6, 400 MHz, 296 K): δ 6.71 (s, 2 H), 6.87 (dd, J
) 3, 3 Hz, 2 H), 7.06 (d, J ) 7 Hz, 1 H), 7.11 (dd, J ) 7, 7 Hz,
2 H), 7.23 (dd, J ) 3, 3 Hz, 2 H), 7.54 (d, J ) 7 Hz, 2 H). 13C
NMR (CD2Cl2, 100 MHz, 296 K): δ 103.13, 126.85, 127.46,
128.51, 129.03, 129.31, 129.54, 130.04, 130.60. Anal. Calcd for
(Barf)ZrBr3 (4b) was contaminated by what appeared to be
residual Me3SiNMe2 and Me3SiBr. As the attempted removal
of these impurities resulted in severely reduced yield and the
impurities had little or no detrimental effect on the subsequent
reactions of the complex, the powder was used without further
purification. The yield calculated for 2b‚0.5Me3SiNMe2‚0.5Me3-
1
SiBr was 63%. H NMR (C6D6, 400 MHz, 296 K): δ 6.34 (s, 2
H), 6.93 (m, 2 H), 7.33 (m, 2 H), 7.65 (s, 1 H), 7.97 (s, 2 H).
Broad peaks in the aromatic region appear to indicate the
presence of dimerized or oligomerized forms of (Barf)ZrBr3.
(2-P h en ylin d en yl)(2-(3,5-bis(tr iflu or om eth yl)p h en yl)-
in d en yl)zir con iu m Dich lor id e (6a ). A 50 mL Schlenk tube
was charged with 2-(3,5-bis(trifluoromethyl)phenyl)indene
(0.113 g, 0.344 mmol) and ether (10 mL). The solution was
cooled to -78 °C, and butyllithium (2 M in hexane, 0.19 mL,
0.38 mmol) was added by syringe. The mixture was warmed
to room temperature and stirred for 10 min. The green-orange
solution was cooled to -78 °C, and the slurry was transferred
by cannula to a 100 mL Schlenk tube containing 3a (0.123 g,
0.316 mmol) in toluene (25 mL) at 0 °C. The green slurry was
allowed to warm to room temperature, and after stirring for 6
h, the solution was orange. The mixture was stirred for an
additional 16 h and then was evaporated to dryness. The
orange powder was extracted with toluene (25 mL) and filtered
through Celite. The Celite was washed with toluene (10 mL).
The combined filtrates were concentrated to a volume of 5 mL,
and the solution was stored at -20 °C for 16 h to give a yellow-
orange powder. Recrystallization from ether (8 mL) afforded
6a as yellow microcrystals (0.092 g, 42%). 1H NMR (C6D6, 400
MHz, 296 K): δ 5.87 (s, 2 H), 6.23 (s, 2 H), 6.88 (m, 4 H), 7.06
(dd, 2 H, J ) 3, 3 Hz), 7.08-7.15 (m, 3 H) 7.24 (dd, 2H, J ) 3,
3 Hz), 7.29 (m, 2 H), 7.62 (br s, 2 H), 7.67 (br s, 1 H). Anal.
Calcd for C32H20Cl2F6Zr: C, 56.47; H, 2.96. Found: C, 56.46;
H, 2.86.
(2-P h en ylin d en yl)(2-(3,5-bis(tr iflu or om eth yl)p h en yl)-
in d en yl)zir con iu m Dibr om id e (6b). A 50 mL Schlenk tube
was charged with 2-(3,5-bis(trifluoromethyl)phenyl)indene
(0.175 g, 0.53 mmol) and ether (10 mL). The solution was
cooled to -78 °C, and butyllithium (1.6 M in hexane, 0.34 mL,
0.54 mmol) was added by syringe. The mixture was warmed
to room temperature and stirred for 10 min. The green-orange
solution was cooled to -78 °C, and the slurry was transferred
by cannula to a 100 mL Schlenk tube containing 3b (0.270 g,
0.517 mmol) in toluene (15 mL) at -78 °C. The orange slurry
was stirred at -78 °C for 20 min and then allowed to warm to
room temperature and was stirred for 16 h. The orange
solution was evaporated to dryness. The orange powder was
extracted with toluene (15 mL) and filtered through Celite.
The Celite was washed with toluene until the fitrates were
colorless. The combined filtrates were evaporated to dryness.
Recrystallization from ether (8 mL) afforded 6b as orange
needles (three crops, 0.153 g, 39%). 1H NMR (CD2Cl2, 400 MHz,
296 K): δ 6.53 (s, 2 H), 6.64 (s, 2 H), 7.21 (dd, J ) 3, 3 Hz, 2
H), 7.28 (dd, J ) 3, 3 Hz, 2 H), 7.35 (dd, J ) 3, 3 Hz, 2 H),
7.45 (m, 3 H), 7.55 (m, 4 H), 7.82 (br s, 2 H), 7.85 (br s, 1 H).
13C NMR (CD2Cl2, 100 MHz, 296 K): δ 104.06, 104.39, 122.16
(septuplet, J C-F ) 4 Hz), 123.70 (q, J C-F ) 271 Hz), 125.97,
126.05, 126.86, 127.04, 127.14, 127.08, 127.32, 127.48, 129.31,
129.54, 131.89 (q, J C-F ) 33 Hz), 132.18, 133.26, 133.72,
136.19. Anal. Calcd for C32H20Br2F6Zr: C, 49.95; H, 2.62.
Found: C, 49.82; H, 2.66.
C
15H11Br3Zr: C, 34.50; H, 2.12. Found: C, 34.21; H, 2.21.
2-(3′,5′-B is (t r iflu o r o m e t h y l)p h e n y l)in d e n y lzir c o -
n iu m Tr ich lor id e (4a ). A 100 mL Schlenk tube was charged
with Zr(NMe2)4 (1.260 g, 4.713 mmol), 1-methyl-2-(3′,5′-bis-
(trifluoromethyl)phenyl)indene (1.505 g, 4.58 mmol), and
toluene (30 mL). The green-brown solution was stirred at room
temperature under slightly reduced pressure for 2.5 h and then
was evaporated to dryness. The green-brown solid was ex-
tracted with pentane (30 mL) and filtered through a cannula
fitted with a double layer of filter paper. The resulting pentane
solution was concentrated to a volume of 8 mL and stored at
-50 °C overnight. The resulting green-brown crystals (2) were
isolated, dried in vacuo, and redissolved in CH2Cl2 (20 mL).
The solution was cooled to 0 °C and chlorotrimethylsilane (2
mL, 15.8 mmol) was added by syringe. The turbid yellow
solution was allowed to warm to room temperature, stirred
for 1 h, and then concentrated to a volume of 1 mL. The
solution was diluted with toluene (30 mL), and the resulting
suspension was stirred for 24 h to afford a lemon yellow
powdery solid (1.390 g). 1H NMR spectroscopic analysis
revealed that the desired (Barf)ZrCl3 (4a ) was contaminated
by what appeared to be residual Me3SiNMe2. As the attempted
removal of these impurities resulted in severely reduced yield
and the impurities had little or no detrimental effect on the
subsequent reactions of the complex, the powder was used
1
without further purification. H NMR (CDCl3, 400 MHz, 296
K): δ 8.19-8.17 (br, 1 H), 8.10 (br, 2 H), 7.99 (br, 1 H), 7.83
(br, 1 H), 7.77 (br, 1 H), 7.61 (br, 2 H), 7.53 (appears as poorly
resolved dd, 2 H), 7.44-7.38 (br, 1 H), 7.30 (br, 2 H), 7.20 (m,
1 H), 7.03 (br, 2 H), 6.95 (s, 1 H), 6.83 (br, 1 H), 2.45 (br, 6 H),
0.41 (s, 9 H). Broad peaks in the aromatic region appear to
indicate the presence of dimerized or oligomerized forms of
(Barf)ZrCl3.
2-(3′,5′-B is (t r iflu o r o m e t h y l)p h e n y l)in d e n y lzir c o -
n iu m Tr ibr om id e (4b). A 100 mL Schlenk tube was charged
with 2 (0.385 g, 0.70 mmol) and CH2Cl2 (20 mL). The yellow
solution was cooled to 0 °C, and bromotrimethylsilane was
added by syringe. The solution turned bright yellow and was
stirred at 0 °C for 30 min. The mixture was warmed to room
temperature, stirred for an additional 2 h, and then evaporated
to dryness. The yellow powder was extracted with toluene (25
mL) and filtered by cannula. The yellow solution was stored
at -20 °C for 10 h. The solution was filtered by cannula, and
the resulting bright yellow powder was dried in vacuo (0.350
(2-P h en ylin d en yl)(2-(3,5-d im eth ylp h en yl)in d en yl)zir -
con iu m Dibr om id e (7). A 50 mL Schlenk tube was charged
with 2-(3,5-dimethylphenyl)indene (0.315 g, 1.43 mmol) and
ether (10 mL). The solution was cooled to -78 °C, and
butyllithium (1.6 M in hexane, 0.94 mL, 1.5 mmol) was added
by syringe. The mixture was warmed to room temperature and
stirred for 1 h. The yellow-orange solution was cooled to -78
°C, and the slurry was transferred by cannula to a 100 mL
Schlenk tube containing 1 (0.700 g, 1.34 mmol) in toluene (15
mL) at -78 °C. The orange slurry was stirred at -78 °C for
1
g). H NMR spectroscopic analysis revealed that the desired

386 Organometallics, Vol. 18, No. 3, 1999
Tagge et al.
1
20 min and then allowed to warm to room temperature and
was stirred for 16 h. The orange solution was evaporated to
dryness. The orange powder was extracted with toluene and
filtered through Celite. The Celite was washed with toluene
until the fitrates were colorless. The combined filtrates were
evaporated to dryness. Recrystallization from methylene chlo-
ride (8 mL)/ether (8 mL) afforded 7 as orange blocks (three
greenish in color. No changes in the H NMR spectrum were
detected upon the color change.
B is (2-(3′,5′-b is (t r iflu o r o m e t h y l)p h e n y l)in d e n y l)-
zir con iu m Dibr om id e (10b). A 50 mL Schlenk tube was
charged with 2-(3′,5′-bis(trifluoromethyl)phenyl)indene. The
tube was removed form the box and charged with Et2O (10
mL) and cooled to -40 °C. Butyllithium was added dropwise
by syringe, and the yellow solution was stirred at - 40 °C for
15 min. The mixture was allowed to warm to room tempera-
ture over 20 min and then was transferred by cannula to a
100 mL Schlenk tube containing 4b in Et2O at -40 °C. The
tube was allowed to warm to room temperature, and the
mixture became homogeneous. The orange mixture was stirred
at room temperature for 3 h and then was evaporated to
dryness. The orange solid was dissolved in toluene (4 mL) and
filtered through sintered glass filter paper by cannula into a
50 mL Schlenk tube. Crystallization from toluene at -50 °C
afforded 10b as yellow microcrystals in 61% yield (3 crops).
1H NMR (C6D6, 400 MHz, 296 K): δ 5.78 (s, 4H), 6.87 (dd, 4H,
J ) 3, 3.5 Hz), 7.17 (dd, 4H, J ) 3, 3.5 Hz), 7.61 (br s, 4H),
7.66 (br s, 2H). Anal. Calcd for C34H18Br2F12Zr: C, 45.10; H,
1
crops, 0.56 g, 63%). H NMR (C6D6, 400 MHz, 296 K): δ 2.21
(s, 6 H), 6.51 (s, 2 H), 6.52 (s, 2 H), 6.80 (br s, 1 H), 6.91 (m, 4
H), 7.0-7.2 (m, partially obscured by solvent resonance), 7.43
(m, 2 H). 13C NMR (CD2Cl2, 100 MHz, 296 K): δ 21.57, 104.59,
104.65, 125.06, 125.72, 125.74, 126.86, 126.90, 127.11, 127.14,
127.22, 129.12, 129.23, 130.89, 132.85, 132.89, 133.37, 133.63,
139.06. Anal. Calcd for
Found: C, 58.05; H, 3.91.
C32H26Br2Zr: C, 58.10; H, 3.96.
(2-P h en ylin d en yl)(1-m eth yl-2-p h en ylin d en yl)zir con i-
u m Dich lor id e (8). Butyllithium (2.5 M in hexanes, 0.43 mL,
1.08 mmol) was added by syringe to a solution of 1-methyl-2-
phenylindene (0.212 g, 1.029 mmol) in diethyl ether (25 mL)
at -78 °C. The light yellow solution was allowed to warm to
room temperature, stirred for an additional 30 min, and then
evaporated to dryness. The white powdery solid was combined
with 3a (0.400 g, 1.029 mmol) and toluene (50 mL). The
resulting suspension was stirred for 24 h at room temperature
and gradually became a turbid yellow solution. The mixture
was filtered through a glass frit packed with Celite and then
evaporated to dryness. The resulting yellow solid was recrys-
tallized from CH2Cl2 (10 mL) layered with pentane (30 mL)
at -50 °C to afford 8 (0.181 g, 31%). 1H NMR (C6D6, 400 MHz,
296 K): δ 7.41 (d, 2 H, J ) 11.2 Hz), 7.30 (d, 2 H, J ) 10.8
Hz), 7.24-6.80 (m, 13 H), 6.73 (d, 1 H, J ) 11.2 Hz), 6.50 (d,
1 H, J ) 3.2 Hz), 6.26 (d, 1 H, J ) 3.3 Hz), 5.98 (s, 1 H), 2.42
(s, 3 H). 13C NMR (CDCl3, 125 MHz, 296 K): δ 133.75 (C),
133.10 (C), 132.38 (C), 131.41 (C), 129.54 (C), 129.06 (C-H),
128.90 (C-H), 128.70 (C-H), 128.67 (C-H), 128.14 (C-H),
126.95 (C), 126.72 (C-H), 126.58 (C-H), 126.56 (C-H), 126.43
(C-H), 126.26 (C-H), 125.58 (C-H), 125.05 (C), 124.90 (CH),
124.56 (C), 124.35 (C-H), 123.68 (C-H), 121.43 (C), 104.34
(C-H, Cp), 100.70 (C-H, Cp), 99.00 (C-H, Cp), 12.54 (CH3).
Anal. Calcd for C31H24Cl2Zr: C, 66.65; H, 4.33. Found: C,
66.92; H, 4.36.
2.00. Found: C, 44.17; H, 1.91. HRMS (EI). m/e calcd for
91
C
34H18Br2F12Zr: 901.863070 (79Br290Zr); 902.864006 (79Br2
-
Zr); 903.861024 (79Br81Br90Zr); 904.861960 (79Br81Br91Zr);
905.858978
(
81Br290Zr). Found: 901.864656; 902.862248;
903.860369; 904.862783; 905.858306.
(2-(3′5′-Bis(t r iflu or om et h yl)p h en yl)in d en yl)(2-(3′,5′-
d im eth ylp h en yl)in d en yl)zir con iu m Dibr om id e (11). A 50
mL Schlenk tube was charged with 2-(3′,5′-dimethylphenyl)-
indene and Et2O (10 mL), and the mixture was cooled to -40
°C. Butyllithium was added dropwise by syringe, and the
orange solution was allowed to warm to room temperature over
a period of 20 min. The solution was transferred by cannula
to a 100 mL Schlenk tube containing 4b in Et2O (20 mL) at
-40 °C. The mixture immediately turned green. As the
mixture was allowed to warm to room temperature (20 min),
it turned orange and became homogeneous. The solution was
stirred for 1 h at room temperature and then was evaporated
to dryness. The orange solid was dissolved in toluene (15 mL)
and filtered through sintered glass filter paper by cannula into
a 50 mL Schlenk tube. Successive crystallization from toluene
afforded 11 as red crystals in 45% yield. As the 1H NMR
spectrum showed that 11 was contaminated with 0.05 equiv
of bis(2-(3′,5′-dimethylphenyl)indenyl)zirconium dibromide, the
fraction was recrystallized. The resulting red crystals (0.035
g, 16%) were still contaminated with 0.02 equiv of bis(2-(3′,5′-
dimethylphenyl)indenyl)zirconium dibromide (as judged by
NMR). However, since further purification would have resulted
in a substantial reduction in yield, the impurity was small,
and the catalytic behavior of the impurity was known, the
effect of the contaminant on the catalytic results of 11 was
judged to be insignificant. Thus, the material was used without
further purification. 1H NMR (CD2Cl2, 400 MHz, 296 K): δ
2.38 (s, 6 H), 6.59 (s, 2 H), 6.63 (s, 2 H), 7.06 (s, 1 H), 7.18 (dd,
2 H, J ) 3, 3 Hz), 7.20 (s, 2 H), 7.29 (m, 4 H), 7.52 (dd, 2 H),
7.84 (br s, 3 H). 13C NMR (CD2Cl2, 100 MHz, 296 K): δ 21.40,
104.30, 104.50, 122.10 (br), 124.92, 125.87, 125.99, 126.90,
(2-P h en ylin den yl)(1-m eth yl-2-(3′,5′-bis(tr iflu r om eth yl)-
p h en yl)in d en yl)zir con iu m Dich lor id e (9). Butyllithium
(2.5 M in hexanes, 0.43 mL, 1.08 mmol) was added by syringe
to a pale yellow solution of 1-methyl-2-(3′,5′-bis(trifluorom-
ethyl)phenyl)indene (0.352 g, 1.029 mmol) in diethyl ether (20
mL) at -78 °C. The yellow solution was allowed to warm to
room temperature, stirred for an additional 30 min, and then
evaporated to dryness. The resulting pale yellow solid was
washed with pentane (20 mL) and then combined with 3a
(0.400 g, 1.029 mmol) and toluene (50 mL). The suspension
was stirred for 24 h at room temperature and gradually
became a turbid yellow solution. The mixture was filtered
through a glass frit packed with Celite and then evaporated
to dryness. The yellow solid was recrystallized from CH2Cl2
layered with pentane at -50 °C to afford 9‚1/6‚CH2Cl2 (0.245
1
g, 34%). H NMR (C6D6, 400 MHz, 296 K): δ 7.67 (s, br, 1 H),
127.21, 127.32 (br), 127.42, 131.29, 131.66, 131.91 (q, J CF
)
7.64 (s, br, 2 H), 7.30-6.78 (m, 13 H), 6.43 (d, 1 H, J ) 2.4
33 Hz), 133.00, 133.81, 136.27, 139.02, 149.48. HRMS(EI). m/e
calcd for C34H24Br2F6Zr: 793.919601 (79Br290Zr); 794.920537
Hz), 6.19 (d, 1 H, J ) 2.4 Hz), 5.59 (s, 1 H), 5.32 (s, 1/3 H,
CH2Cl2), 2.24 (s, 3 H). 13C NMR (CDCl3, 125 MHz, 296 K): δ
(79Br291Zr); 795.917555 (79Br81Br90Zr); 796.918491(79Br81Br91
-
2
135.91 (C-H), 133.59 (C), 132.58 (C), 131.47 (C-CF3, J CF
)
Zr); 797.915508 (81Br290Zr). Found: 793.919335; 794.912828;
795.914997; 796.917847; 797.914606.
33 Hz), 130.76 (C), 130.51 (C), 129.02 (C-H), 128.98 (C-H),
128.80 (C-H), 126.87 (C-H), 126.81 (C-H), 126.77 (C-H),
126.62 (C-H), 126.52 (C-H), 126.25 (C-H), 126.21 (C), 125.34
(C-H), 125.05 (C), 124.09 (C-H), 123.86 (C), 123.23 (CF3, J CF
) 273 Hz), 123.17 (C), 121.24 (C-H, br), 119.25 (C), 102.70
(C-H, Cp), 101.76 (C-H, Cp), 99.30 (C-H, Cp), 12.12 (CH3).
Anal. Calcd for C33H22F6ZrCl2‚1/6‚CH2Cl2: C, 55.86; H, 3.37.
Found: C, 56.20; H, 3.18. After having been stored for 3-4
weeks in the drybox in a clear vial the yellow compound turned
1-Meth yl-2-(3′,5′-bis(tr iflu or om eth yl)ph en yl)in den e an d
3-Meth yl-2-(3′,5′-bis(tr iflu or om eth yl)ph en yl)in den e (1Me-
Ba r f). A solution of 2-(3′,5′-bis(trifluoromethyl)phenyl)indene
(1.819 g, 5.54 mmol) in tetrahydrofuran (30 mL) was cooled
to -78 °C, and butyllithium (2.5 M in hexanes, 2.33 mL, 5.82
mmol) was added dropwise. The resulting orange-brown
solution was allowed to warm to room temperature and stirred
for an additional 30 min. Iodomethane (1.20 mL, 19 mmol)

Mixed Ligand Metallocenes as Catalysts
Organometallics, Vol. 18, No. 3, 1999 387
was added by syringe; the green reaction mixture was stirred
for 20 h at room temperature. Methanol (20 mL) was added
to quench excess organometallic reagents, and the mixture was
evaporated to dryness. The resulting brown solid was extracted
with toluene (30 mL) and filtered through a glass frit packed
with Celite. The solution was extracted with H2O (2 × 10 mL)
and saturated NaCl solution (2 × 10 mL), dried over MgSO4,
and then evaporated to dryness. Crystallization from hexanes
homogeneous. The yellow solution was added by pipet to a 30
mL jar containing MAO (0.360 g; Akzo Type 4 previously
evaporated to dryness) in toluene (15 mL). The mixture turned
orange and was aged for 5 min. The solution was transferred
by pipet to a 50 mL pressure tube and pressurized to 250 psi
with argon. The catalyst solution was injected into a 300 mL
stainless steel Parr reactor containing 100 mL of liquid
propylene at 16 °C. The temperature immediately climbed to
22 °C, but stabilized at 20 °C within 1 min. The mixture was
stirred at 20 °C for 20 min and then quenched with methanol
(15 mL). The white polymer was precipitated with acidified
methanol and dried in vacuo at 40 °C to constant weight (2.832
g, 1.4 kg/(mol(Zr)‚h)). 13C NMR (C2H2Cl4/C2D2Cl4 (4/1), 100
MHz, 373 K): [mmmm] 21%.
1
afforded yellow crystals of 1Me-Barf (1.073 g, 73%). H NMR
(CDCl3, 400 MHz, 296 K): δ 7.87 (s, 2 H), 7.75 (s, 1 H), 7.49
(d, 1 H, J ) 7.3 Hz), 7.42 (d, 1 H, J ) 7.5 Hz), 7.37 (t, 1 H, J
) 7.3 Hz), 7.26 (td, 1 H, J ) 7.3, 1.1 Hz), 3.78 (s, 2 H), 2.33 (s,
3 H). Anal. Calcd for C18H12F6: C, 63.16; H, 3.53. Found: C,
63.12; H, 3.62. Repeated crystallization from hexanes gave a
mixture of 1Me-Barf and 3Me-Barf (309 mg) in 4:1 ratio. 3Me-
Barf was identified from its characteristic pattern in the
aliphatic region of the 1H NMR spectrum: 3.14 (q, 1 H, J )
7.0 Hz), 0.87 (d, 3 H, 7.1 Hz). 1Me-Barf and 3Me-Barf form
the same product upon deprotonation.
X-r a y Cr ysta llogr a p h ic An a lysis of (2P h In d )(DMP In -
d )Zr Br 2 (7). An orange rectangular crystal of 7 with ap-
proximate dimensions of 0.13 × 0.13 × 0.05 mm3, grown from
a solution of toluene, was mounted on a glass fiber in paratone
oil at -80 °C using an improvised cold stage. All measure-
ments were made on a Siemens SMART diffractometer with
graphite-monochromated Mo KR radiation. Cell constants and
an orientation matrix for data collection obtained from a least-
squares refinement using the setting angles of 4627 carefully
centered reflections with I > 10σ(I) in the range 2.8l° < 2θ <
52.00° corresponded to a primitive monoclinic cell with dimen-
sions a ) 13.030(1) Å, b ) 14.499(1) Å, â ) 112.164(1)°, c )
14.774(1) Å, and d ) 2584.9(3) Å3. For Z ) 4 and fw ) 769.53,
the calculated density is 1.98 g/cm3. The intensities of sym-
metry-equivalent reflections demonstrated a Laue class of 2/m.
The systematic absence of h0l, h+ l * 2n, and 0k0, k * 2n,
uniquely determines the space group to be P2l/n. Wilson
statistics supported a centric space group. The data were
collected at a temperature of - 112 ( 1 °C using the ω scan
technique to a maximum 2θ value of 52.0°.
(1Me-2-P h In d )(Ba r f)zir con iu m Dich lor id e (12). Butyl-
lithium (2.5 M in hexanes, 0.55 mL, 1.38 mmol) was added by
syringe to a solution of 1-methyl-2-phenylindenyl (0.277 g, 1.31
mmol) in diethyl ether (25 mL) at -78 °C. The light yellow
solution was allowed to warm to room temperature and stirred
for an additional 15 min. The mixture was evaporated to
dryness to yield a white powdery solid, which was then
combined with 4a (0.695 g, ca. 1.31 mmol) and toluene (40 mL)
at 0 °C. The resulting dark green solution was allowed to warm
to room temperature and stirred for 40 h, during which time
the solution gradually became lemon yellow. The turbid
solution was filtered through a glass frit packed with Celite
and then evaporated to dryness. Recrystallization from a CH2-
Cl2 (5 mL)/pentane (5 mL) solution at -50 °C afforded 12‚1/
1
6‚CH2Cl2 as orange crystals (0.200 g, 28%). H NMR (CDCl3,
500 MHz, 296 K): δ 7.84 (s, 2 H, br), 7.82 (s, 1 H, br), 7.52 (t,
2 H, J ) 7.5 Hz), 7.43 (m, 3 H), 7.36 (m, 2 H), 7.29 (m, 2 H),
7.20 (t, 1 H, J ) 6.0 Hz), 7.08 (q, 2 H, J ) 7.0 Hz), 6.68 (d, 1
H, J ) 2 Hz), 6.38 (d, 1 H, J ) 2 Hz), 5.99 (s, 1 H), 5.32 (s, 1/3
H, CH2Cl2), 2.53 (s, 3 H). 13C NMR (CD2Cl2, 125 MHz, 296 K):
δ 135.48 (C), 133.20 (C), 132.23 (C), 132.20 (C), 131.62 (C-
Data were integrated using the program SAINT with a 1.6
× 1.6 × 0.6° box. A total of 12 337 reflections were collected.
A correction for decay was deemed unnecessary. An empirical
absorption correction, XPREP, was applied, which resulted in
transmission factors ranging from 0.744 to 0.963. The data
were corrected for Lorentz and polarization effects. The linear
2
CF3, J C-F ) 34 Hz), 130.23 (C), 129.03 (CH), 128.61 (CH),
absorption coefficient, µ, for Mo KR radiation is 35.93 cm-1
.
128.44 (C-H), 126.87 (C-H), 126.71 (C-H), 126.70 (C-H),
126.54 (C-H), 126.45 (C-H), 126.24 (C-H), 125.90 (C), 125.17
(C-H), 125.01 (C), 124.43 (C), 124.15 (C-H), 124.13 (C-H),
123.22 (CF3, J C-F ) 272 Hz), 121.70 (C-H, br), 102.09 (C-H,
Cp), 101.20 (C-H, Cp), 98.51 (C-H, Cp), 12.39 (CH3). Anal.
Symmetry-equivalent, non-Friedel reflections were averaged
to produce 4740 unique reflections (Rint ) 0.048).
The structure was solved by direct methods and expanded
using Fourier techniques. All non-hydrogen atoms were refined
anisotropically. The maximum and minimum peaks on the
final difference Fourier map corresponded to 0.67 and -0.97
e/Å3, respectively. Hydrogen atoms were included at idealized
positions, 0.95 Å from their parent atoms. The final cycle of
full -matrix least-squares refinement was based on 2492
observed reflections (I > 3σ(I)) and 316 variable parameters
and converged (largest parameter shift was 0.041 times its esd)
with unweighted and weighted agreement factors of R ) 0.037
and Rw ) 0.045.
Calcd for
Found: C, 56.11; H, 3.09.
C33H22Cl2F6Zr‚1/6‚CH2Cl2: C, 56.20; H, 3.18.
(Ba r f)(1Me-Ba r f)zir con iu m Dich lor id e (13). Butyllith-
ium (2.5 M in hexanes, 0.40 mL, 1.00 mmol) was added by
syringe to the solution of 1Me-Barf (0.328 g, 0.958 mmol) in
diethyl ether (30 mL) at -78 °C. The light yellow solution was
allowed to warm to room temperature and stirred for an
additional 2.5 h. The mixture was evaporated to dryness to
yield a gray powdery solid, which was washed with pentane,
filtered, and then dried in vacuo. The solid was combined with
solid 4a and toluene (50 mL), and the mixture was stirred for
40 h at room temperature. The turbid yellow solution was
filtered through a glass frit packed with Celite and then
evaporated to dryness. Precipitation from CH2Cl2 (10 mL) at
-50 °C afforded 13 as a yellow powder (0.100 g, 13%). 1H NMR
(CDCl3, 500 MHz, 296 K): δ 7.56 (s, 2 H, br), 7.48 (s, 2 H, br),
7.29 (d, 1 H, J ) 8.5 Hz), 7.08 (m, 2 H), 6.90 (m, 2 H), 6.83 (t,
2 H, J ) 7.0 Hz), 6.66 (t, 1 H, J ) 7.5 Hz), 6.00 (d, 1 H, J )
2.5 Hz), 5.73 (d, 1 H, J ) 2.5 Hz), 5.48 (s, 1 H), 2.14 (s, 3 H).
19F NMR (C6D6, 282 MHz, 296 K): δ 63.65 (s, 3F), 63.57 (s,
3F). Anal. Calcd for C34H20Cl2F6Zr: C, 50.61; H, 2.43. Found:
C, 50.90; H, 2.72.
The standard deviation of an observation of unit weight was
1.43. The weighting scheme was based on counting statistics
and included a factor (p ) 0.03) to downweight the intense
reflections. Plots of ∑w(|Fo| - |Fc|)2 versus |Fo|, reflection order
in data collection, sin θ/λ, and various classes of indices showed
no unusual trends. Neutral atom scattering factors were taken
from Cromer and Waber.50 Anomalous dispersion effects were
51
included in Fcalc
;
the values for Df′ and Df′′ were those of
Creagh and MeAuley.52 The values for the mass attenuation
(50) Cromer, D. T.; Waber, J . T. International Tables for Crystal-
lography; The Kynoch Press: Birmingham, England, 1974; Vol. IV,
Table 2.2 A.
(51) Ibers, J . A.; Hamilton, W. C. Acta Crystallogr. 1964, 17, 781.
(52) Creagh, D. C.; McAuley, W. J . In International Tables for
Crystallography; Wilson, A. J . C., Ed.; Kluwer Academic Publishers:
Boston, 1992; Vol. C.; pp 219-222.
Rep r esen ta tive P olym er iza tion P r oced u r e (7/MAO). In
the drybox a 5 mL volumetric flask was charged with 7 (0.0041
g, 0.0062 mmol) and toluene. The solution was stirred until

388 Organometallics, Vol. 18, No. 3, 1999
Tagge et al.
coefficients were those of Creagh and Hubbel.53 All calculations
were performed using the teXsan crystallographic software
package of the Molecular Structure Corporation.
dation (CHE-9615699) and by Amoco Chemical Com-
pany. C.D.T. thanks the National Institutes of Health
for NationalResearch Service Award No. 5, F32GM17850-
02. R.M.W. acknowledges support from the NSF’s Alan
T. Waterman Award.
Ack n ow led gm en t. The structural data was col-
lected by Dr. R. E. Powers and Dr. F. J . Hollander,
director of the U.C. Berkeley X-ray Diffraction facility
(CHEXRAY), and solved by Dr. T. K. Lal. We thank Dr.
E. J . Moore of Amoco for helpful discussions. This
research was supported by the National Science Foun-
Su p p or tin g In for m a tion Ava ila ble: Tables of crystal,
data collection, positional parameters, bond distances and
angles, and polymer NMR data (12 pages). See any current
masthead page for ordering and Internet access instruc-
tions.
(53) Creagh, D. C.; Hubbell, J . H. In International Tables for
Crystallography; Wilson, A. J . C., Ed.; Kluwer Academic Publishers:
Boston, 1992; Vol. C.; pp 200-206.
OM9807957