Some new exo,exo-bis(isodicyclopentadienyl)titanium and -zirconium dichloride derivatives: Synthesis, characterization, and evaluation as propene polymerization catalysts

Article abstract of DOI:10.1021/om980542d

Exo,exo derivatives of the efficient catalyst precursors (diisodicyclopentadienyl)titanium and -zirconium dichloride substituted at the central position have been synthesized. These compounds have been characterized by solution NMR measurements, which als

Full text of DOI:10.1021/om980542d

Organometallics 1998, 17, 4897-4903
4897
Som e New exo,exo-Bis(isod icyclop en ta d ien yl)tita n iu m
a n d -zir con iu m Dich lor id e Der iva tives: Syn th esis,
Ch a r a cter iza tion , a n d Eva lu a tion a s P r op en e
P olym er iza tion Ca ta lysts
Olivier Gobley,† Philippe Meunier,† Bernard Gautheron,*,† J udith C. Gallucci,‡
Gerhard Erker,§ Marc Dahlmann,§ J effrey D. Schloss,‡ and Leo A. Paquette*,‡
Laboratoire de Synthe`se et d’Electrosynthe`se Organome´talliques Associe´ au CNRS, UMR 5632,
Universite´ de Bourgogne, BP 138, 21004 Dijon Cedex, France, Department of Chemistry,
The Ohio State University, Columbus, Ohio 43210, and Organisch-Chemisches Institut der
Westfa¨lischen Wilhelms-Universita¨t, Corrensstrasse 40, D-48149 Mu¨nster, Germany
Received J une 26, 1998
Exo,exo derivatives of the efficient catalyst precursors (diisodicyclopentadienyl)titanium
and -zirconium dichloride substituted at the central position have been synthesized. These
compounds have been characterized by solution NMR measurements, which also permitted
the calculation of rotational barriers. The solid-state structures of exo,exo-bis(3-diphen-
ylphosphinoisodicyclopentadienyl)titanium and -zirconium dichloride were determined by
X-ray crystallography. Unfortunately, after activation by methylalumoxane, these complexes
are shown to serve as poor catalysts for the polymerization of propene.
In tr od u ction
The rotational barrier of the analogous zirconium
dichloride complex is much lower (∼6 kcal mol-1). This
low energy may be the underlying reason for the lack
of stereoselectivity (even at low temperature) exhibited
by this catalyst in propene polymerization.
Homogeneous group 4 metallocene/methylalumoxane
Ziegler catalysts have played a very important role in
the formation of stereoregular R-olefin polymers.1 The
most common ligands found in titanocene and zir-
conocene complexes have planar structures as, for
example, the η5-cyclopentadienyl or indenyl systems.
For the isodicyclopentadienyl ligand, group 4 metals can
be selectively coordinated to the diastereotopic exo or
endo faces, respectively, by carefully selecting the
experimental conditions.2 In the presence of methyl-
alumoxane, some of these complexes exhibit interesting
activity and selectivity as homogeneous Ziegler-Natta
catalysts.3 It was demonstrated by dynamic NMR
spectroscopy3 that exo,exo-bis(isodicyclopentadienyl)-
titanium dichloride exhibits a chiral C2-symmetric
structure in solution that is characterized by a bis-
lateral (anti) orientation of the annulated bicyclo[2.2.1]-
heptene moieties at the bent-metallocene wedge. The
activation energy for the conformational inversion of
Since the preparation of ansa metallocenes derived
from isodicyclopentadienyl ligands has not been suc-
cessful, it was of interest to synthesize exo,exo-bis-
(isodicyclopentadienyl)titanium or -zirconium dichlo-
rides substituted in the central position and to make
the complexes as stereorigid as possible to enhance their
rotational barriers.
Resu lts a n d Discu ssion
Isodicyclopentadienide anion (1) was obtained by
conventional reaction of isodicyclopentadiene and n-
butyllithium in ether at -80 °C.4 When exposed to
various electrophilic reagents in THF solution, 1 gave
in each case a mixture of exo and endo isomers 2 and
5
2′ as defined by NMR analysis. The 3-substituted
that complex is ∆Gqrot(198 K) ) 9.8 ( 0.4 kcal mol-1
.
isodicyclopentadienide anions, generated by subsequent
treatment of 2 and 2′ with n-butyllithium in tetrahy-
drofuran, gave rise to metallocenes 4-9 in totally
† Universite´ de Bourgogne.
‡ The Ohio State University.
§ Institut der Westa¨lischen Wilhelms-Universita¨t.
(1) For example: (a) J ordan, R. F. Adv. Organomet. Chem. 1991,
32, 325. (b) Corradini, P.; Guerra, G. Prog. Polym. Sci. 1991, 16, 239.
(c) Mo¨hring, P. C.; Coville, N. J . J . Organomet. Chem. 1994, 479, 1.
(d) Kaminsky, W. Catal. Today 1994, 20, 257. (e) Gupta, V. K.; Satish,
S.; Bhardwaj, I. S. Rev. Macromol. Chem. Phys. 1994, C34 (3), 439. (f)
Brintzinger, H. H.; Fischer, D.; Mu¨lhaupt, R.; Rieger, B.; Waymouth,
R. Angew. Chem., Int. Ed. Engl. 1995, 34, 1143.
(2) (a) Paquette, L. A.; Moriarty, K. J .; Meunier, P.; Gautheron, B.;
Croq, V. Organometallics 1988, 7, 1873. (b) Paquette, L. A.; Moriarty,
K. J .; Meunier, P.; Gautheron, B.; Sornay, C.; Rogers, R. D.; Rheingold,
A. L. Organometallics 1989, 8, 2159. (c) Sornay, C.; Meunier, P.;
Gautheron, B.; O’Doherty, G. A.; Paquette, L. A. Organometallics 1991,
10, 2082. (d) Zaegel, F.; Gallucci, J . C.; Meunier, P.; Gautheron, B.;
Sivik, M. R.; Paquette, L. A. J . Am. Chem. Soc. 1994, 116, 6466.
(3) Fritze, C.; Knickmeier, M.; Erker, G.; Zaegel, F.; Gautheron, B.;
Meunier, P.; Paquette, L. A. Organometallics 1995, 14, 5446.
(4) Paquette, L. A.; Moriarty, K. J .; Meunier, P.; Gautheron, B.;
Sornay, C.; Rogers, R. D.; Rheingold, A. L. Organometallics 1989, 8,
2159.
(5) (a) Paquette, L. A.; Charumilind, P.; Kravetz, T. M.; Bo¨hm, M.
C.; Gleiter, R. J . Am. Chem. Soc. 1983, 105, 3126. (b) Paquette, L. A.;
Charumilind, P.; Gallucci, J . C. J . Am. Chem. Soc. 1983, 105, 7364.
(6) Gallucci, J . C.; Gautheron, B.; Gugelchuck, M.; Meunier, P.;
Paquette, L. A. Organometallics 1987, 6, 15.
(7) Ninoreille, S.; Broussier, R.; Amardeil, R.; Kubicki, M. M.;
Gautheron, B. Bull. Soc. Chim. Fr. 1995, 132, 128.
(8) (a) Knickmeier, M.; Erker, G.; Fox, T. J . Am. Chem. Soc. 1996,
118, 9623. (b) Erker, G.; Aulbach, M.; Knickmeier, M.; Wingbermu¨hle,
D.; Kru¨ger, C.; Nolte, M.; Werner, S. J . Am. Chem. Soc. 1993, 115,
4590. (c) Kru¨ger, C.; Lutz, F.; Nolte, M.; Erker, G.; Aulbach, M. J .
Organomet. Chem. 1993, 452, 79. (d) Benn, R.; Grondey, H.; Nolte, R.;
Erker, G. Organometallics 1988, 7, 777.
10.1021/om980542d CCC: $15.00 © 1998 American Chemical Society
Publication on Web 10/10/1998

4898 Organometallics, Vol. 17, No. 22, 1998
Ta ble 1. Com p a r a tive 200 MHz 1H NMR Sp ectr a l Da ta for 4-9 (d p p m /TMS; CDCl3 Solu tion a t 298 K)
compound peripheral bridgehead exo-ethano bridge endo-ethano bridge syn-methano bridge anti-methano bridge
Gobley et al.
R
4
5
5.82 (s)
5.65 (s)
3.29 (s)
3.30 (s)
1.80 (d; J ) 7.3 Hz) 1.06 (d; J ) 7.3 Hz) 1.25 (d; J ) 9.3 Hz) 0.82 (d; J ) 9.3 Hz) 2.15 (s)
1.80 (d; J ) 6.8 Hz) 1.05 (dd; J ) 7.3 Hz; 1.38 (d; J ) 8.9 Hz 1.05 (d; J ) 9.8 Hz) 2.16 (s)
J ) 2.4 Hz)
6
7
6.05 (s)
5.93 (s)
3.30 (s)
3.32 (s)
1.82 (d; J ) 7.3 Hz) 1.02 (d; J ) 7.3 Hz)
1.35 (s)
0.17 (s)
1.81 (d; J ) 6.8 Hz) 0.99 (dd; J ) 1.9 Hz; 1.54 (d; J ) 9.3 Hz) 1.43 (d; J ) 9.3 Hz) 0.17 (s)
J ) 7.3 Hz)
8
9
5.97 (s)
5.82 (s)
3.34 (s)
3.34 (s)
1.89 (d; J ) 7.8 Hz) 1.17 (d; J ) 6.3 Hz) 1.50 (s)
1.32 (d; J ) 9.8 Hz) 7.24-7.35 (m)
1.88 (d; J ) 7.3 Hz) 1.15 (d; J ) 7.3 Hz) 1.58 (d; J ) 9.3 Hz) 1.35 (d; J ) 9.8 Hz) 7.25-7.36 (m)
Ta ble 2. Com p a r a tive 50 MHz 13C NMR Sp ectr a l Da ta for 4-9 (δ p p m /TMS; CDCl3 Solu tion a t 298 K)
ipso
bridge- ethano
methano
bridge
compound quaternary cyclopentadienide
peripheral
109.4
104.3
112.3
109.3
111.6 (s l)
head
bridge
R
4
5
6
7
8
146.6
138.7
149.2
146.4
146.3
141.2
150.1
140.0
42.4
41.8
41.7
41.2
42.6
28.7
28.9
28.6
28.8
28.6
46.1
47.8
47.7
48.9
18.7
17.5
0.6
0.5
not visible 149.5 (d;
46.6 (d;
ipso: 137.9 (d; 1J C-P )13.4 Hz)
1J C-P )14.0 Hz)
J ) 11.6 Hz) ortho: 134.7 (d; 2J C-P ) 21.4 Hz)
me´ta: 128.5 (d; 3J C-P ) 7.3 Hz)
para: 129.0 (s)
9
144.5
138.4 (d;
1J C-P ) 15.9Hz)
108.1 (d;
41.9
29.0
48.1 (d;
J ) 7.9 Hz)
ipso: 137.9 (d; 1J C-P ) 13.4 Hz)
ortho: 134.5 (d; 2J C-P ) 21.3Hz)
me´ta: 128.4 (d; 3J C-P ) 7.9Hz)
para: 129.0 (s)
2J C-P ) 9.8Hz)
Sch em e 1
stereoselective π complexation processes when reacted
with the appropriate metal tri- or tetrahalide.
The 1H and 13C NMR parameters determined for 4-9
at ambient temperature are compiled in Tables 1 and
2. Assignment of signals to individual protons has been
facilitated by reference to similar molecules already
published.6 With regard to the 13C NMR spectra, the
reported values were obtained by the J -modulated
spin-echo program and the chemical shifts were identi-
fied by comparison to data for other known metallocene
However, this is likely to be the result of a fast
equilibrium between metallocene conformers of lower
symmetry on the NMR time scale. Decreasing the
temperature causes the respective diastereotopic pairs
of NMR signals of the less congested anti conformation
to separate in the 1H NMR spectrum below their
coalescence temperatures. In Table 3 are compiled the
results obtained from dynamic NMR experiments. It
is noteworthy that the rotational barrier of the substi-
tuted titanium complexes is approximately 2 kcal mol-1
higher than those of the corresponding bis(isodicyclo-
pentadienyl)titanium dichlorides. The rapid equilibra-
tion of conformations of complex 7 cannot be arrested
dichlorides.6,7 In accord with our earlier results,2 1
H
and 13C NMR chemical shifts of the aliphatic fragment
are characteristic of exo isomers. Those signals due to
the methano and ethano bridges are particularly well
resolved between 0.8 and 1.9 ppm.
As expected, the 13C chemical shifts are influenced
by the nature of the transition metal. For example,
when passing from the titanium complex to its zirco-
nium analogue, the carbons of the Cp ring are shielded
on the order of 2.8-11.1 ppm because of decreased
electronegativity on the part of the metal. For the
ethano and methano bridge carbons, the effect is
reversed and is most important for the methano bridge.
In the case of suitably substituted group 4 metal-
locenes, three different favored conformations may be
observed in solution.8 In the case of the diisodicyclo-
pentadienyltitanium and -zirconium complexes,3 these
could be described as follows: the rotamer characterized
by the localization of the two norbornyl groups outside
of the Cl-M-Cl angle is termed the bis-lateral (anti)
conformation and exhibits C2 symmetry. The bis-
central (syn) conformation with C2v symmetry is adopted
when each norbornane segment is inside of the Cl-M-
Cl angle. The last conformation of C1 symmetry,
characterized by a norbornyl group centered on the Cl-
M-Cl angle and the other one localized outside of this
region, is named lateral-central (gauche-like).
1
on the H NMR time scale.
The molecular structures of 8 and 9 were determined
by X-ray diffraction. Two ORTEP representations of 9
are shown in Figure 1. No drawing of the Ti complex
is displayed since 8 and 9 are isostructural. Selected
bond lengths and angles are reported in Tables 4 and
5. The labeling schemes used for both structures are
the same.
The molecular structures of 8 and 9 correspond to the
anti bent-metallocene conformer, which was observed
previously for the analogous exo,exo-bis(isodicyclopen-
tadienyl)titanium and -zirconium dichlorides.6 A pro-
jection of the substituted isodicyclopentadienyl ligands
onto the MCl2 plane shows a bis-lateral conformation
with the five-membered rings almost eclipsed. A pseudo
2-fold axis bisects the Cl-M-Cl angle for both struc-
tures.
Although all three conformations (Scheme 3) might
be present simultaneously in solution at room temper-
As observed for other pairs of (η5-RCp)2MCl2 com-
pounds with M ) Ti or Zr,6 the Zr-Cl distance is on
average 0.08 Å longer than the Ti-Cl bond. These
distances are slightly smaller than in the analogous
1
ature, the H and 13C NMR spectra of complexes 4-9
are in accord with an apparent C2v-symmetric situation.

Exo,Exo Derivaties of Catalyst Precursors
Organometallics, Vol. 17, No. 22, 1998 4899
Sch em e 2
Sch em e 3
about the bond common to the Cp ring and the norbor-
nane fragment. This bending can be described by the
dihedral angle between the least-squares planes through
atoms C1-C2-C3-C4-C5 and atoms C6-C5-C1-C9
(as an example). For the Ti and Zr structures, these
dihedral angles are 13.5(4)/14.1(4)° and 12.6(3)/13.0(3)°,
respectively. The bending is in the endo direction.
Complexes 4-9 were activated with methylalumox-
ane9 to give homogeneous Ziegler-type propene polym-
erization catalysts. The titanium complexes/MAO cata-
lysts produced atactic polypropylene in toluene solution
(2 bar propene pressure, 0 °C, activity a ≈ 7 g of polymer
(g of Ti)-1 h-1 bar-1 for 4, 6, and 8; -20 °C, a ≈ 40 g of
polymer (g of Ti)-1 h-1 bar-1 for 4, and a ≈ 11 g of
polymer in the same units for 6 and 8).
The corresponding zirconium/MAO catalysts are more
active and stereoselective. In the temperature range
of -50 to +10 °C, the 7/MAO catalyst exhibits a
maximum activity at -20 °C (activity (g of polymer (g
of Zr)-1 h-1 bar-1): a ≈ 286(-50 °C), 517(-40 °C), 633-
(-20 °C), 280(0 °C), 86(+10 °C)). The molecular weight
Mη decreases from ca. 234 600 to ca. 18 500 within this
temperature range. For the 5/MAO catalyst, the activity
is maximum at 0 °C (a ≈ 381 g of polymer (g of Zr)-1
h-1 bar-1) in the temperature range of -40 to +10 °C,
but atactic polypropylene is produced. The last catalyst
(9/MAO) is minimally active (maximum activity at -20
°C: 4 g of polymer (g of Zr)-1 h-1 bar-1).
Ta ble 3. Rota tion a l Activa tion En er gies (∆Gq
r ot
k ca l m ol-1
)
Tc
∆
∆Gq
signal
used
ν
rot
compound
(K) (Hz) (kcal mol-1
)
(isodiCpMe)2TiCl2, 4
(isodiCpMe)2ZrCl2, 5
262 105
231 165
(isodiCpSiMe3)2TiCl2, 6 198 247
(isodiCpSiMe3)2ZrCl2, 7
12.1 ( 0.4
10.4 ( 0.4
8.7 ( 0.4
CpH
CpH
bridgehead
(isodiCpPPh2)2TiCl2, 8
(isodiCpPPh2)2ZrCl2, 9
isodiCp2TiCl2
243
200
55
33
11.5 ( 0.4
9.6 ( 0.4
bridgehead
CpH
9.8 ( 0.4a
isodiCp2ZrCl2
<7a
a
From ref 3.
isodicyclopentadienyl compounds. The Zr-ring centroid
distance is on average 0.13 Å longer than the Ti-ring
centroid distance, and these distances are slightly larger
than in the analogous isodicyclopentadienyl complexes.
The angles about the metal atoms are in the expected
ranges with the ring centroid-Zr-ring centroid (129.02°)
and Cl-Zr-Cl (92.94°) angles slightly smaller and
larger than the respective angles in the titanium
structure (131.85° and 91.84°).
The metal-ring carbon distances are larger than in
the (isodicyclopentadienyl)2MCl2 (M ) Ti or Zr) struc-
tures and indicate that the metal-ring interaction is
asymmetric. These bond lengths are in the ranges of
2.391-2.449 and 2.375-2.452 Å for the titanium com-
pound and 2.514-2.551 and 2.501-2.559 Å for the
zirconium compound.
The stereochemistry of the polypropylenes obtained
at the catalysts derived from 5 and 7, respectively, is
exclusively determined by chain end control;10,11 thus,
the catalysts behave as if they were achiral. At low
temperature (-50 °C), a slightly isotactic polymer is
obtained for the 7/MAO catalyst in toluene (σ ) 0.75,
determined by 13C NMR pentad analysis). Increasing
the polymerization temperature results in rapid loss of
stereocontrol to give atactic material.
Con clu sion
One of the longer metal-ring carbon distances in-
volves the carbon atom bonded to the phosphido group.
In fact, for three out of the four rings in these two
structures, that is the longest metal-ring carbon dis-
tance observed. Like the other two carbon atom sub-
stituents on the Cp ring, the P atom lies significantly
out of the least-squares plane through the Cp ring and
in the direction away from the metal atom for both
structures.
Several compounds from the family of substituted
exo,exo-bis(isodicyclopentadienyl) transition metal com-
plexes have been prepared, and the X-ray structures of
two representative examples have been established. The
rotational barrier of the pentahapto ligands has in-
creased by comparison to the unsubstituted analogues,
(9) Sinn, H.; Kaminsky, W. Adv. Organomet. Chem. 1980, 18, 99.
(10) Erker, G.; Nolte, R.; Aul, R.; Wilker, S.; Kru¨ger, C.; Noe, R. J .
Am. Chem. Soc. 1991, 113, 7594.
As observed in previous structures involving the
isodiCp ligand,6 there is a slight bending of this ligand
(11) Ewen, J . A. J . Am. Chem. Soc. 1984, 106, 6355.

4900 Organometallics, Vol. 17, No. 22, 1998
Gobley et al.
F igu r e 1. Two ORTEP drawings for 9 with atoms drawn with 50% probability ellipsoids. Hydrogen atoms are omitted for
clarity. The view on the right is a projection onto the ZrCl2 plane.
Ta ble 4. Selected Bon d Len gth s (Å) for 8 a n d 9a
barriers were determined at the coalescence temperature of a
suitable pair of signals12 for each compound.
atom-
atom
8
9
atom-
atom
8
9
(M ) Ti) (M ) Zr)
(M ) Ti) (M ) Zr)
Propene polymerization reactions were carried in a Bu¨chi
glass autoclave at 2 bar of propene pressure in toluene,
following the procedure previously described in detail.10 The
molecular weights of the polymers were determined with an
Ubbelohde viscosimeter (Schott AVS 440) in Decalin solution
at 137 °C. The 13C NMR spectra of the polymers were recorded
in 1,2,4-trichlorobenzene/[d6]benzene (4:1) solution at 350 K.
The methyl pentad signals were integrated by a curve-fitting
procedure as previously described and then subjected to a
statistical treatment to determine the partition between
enantiomorphic site control (ω) and end chain stereocontrol
(1-ω), the isotacticity (σ), and the syndiotacticity (1-σ) of the
obtained polymer sample under chain end control.
M-Cl(1)
M-C(1)
2.342(1) 2.4285(8) M-Cl(2)
2.355(1) 2.4375(8)
2.418(4) 2.514(3) M(1)-C(23) 2.430(4) 2.508(3)
2.438(5) 2.517(3) M(1)-C(24) 2.444(4) 2.501(3)
2.449(4) 2.551(3) M(1)-C(25) 2.452(4) 2.554(3)
2.397(4) 2.548(3) M(1)-C(26) 2.375(4) 2.559(3)
2.391(4) 2.529(3) M(1)-C(27) 2.380(4) 2.544(3)
1.402(6) 1.414(4) C(23)-C(24) 1.407(6) 1.414(4)
1.396(6) 1.403(4) C(23)-C(27) 1.395(6) 1.406(4)
1.515(6) 1.517(4) C(23)-C(31) 1.509(6) 1.513(4)
1.414(6) 1.422(4) C(24)-C(25) 1.428(6) 1.428(4)
1.428(6) 1.428(4) C(25)-C(26) 1.415(6) 1.417(4)
1.415(6) 1.406(4) C(26)-C(27) 1.418(6) 1.418(4)
1.518(6) 1.519(4) C(27)-C(28) 1.515(6) 1.504(4)
1.559(7) 1.554(5) C(28)-C(29) 1.554(7) 1.560(5)
M-C(2)
M-C(3)
M-C(4)
M-C(5)
C(1)-C(2)
C(1)-C(5)
C(1)-C(9)
C(2)-C(3)
C(3)-C(4)
C(4)-C(5)
C(5)-C(6)
C(6)-C(7)
Mass spectra were determined with a KRATOS concept IS
instrument (Centre de Spectroscopie Mole´culaire de l’Universite´
de Bourgogne; electronic ionization 70 eV) and a KRATOS
MS.30 (Campus Chemical Instrumentation Center of The Ohio
State University).
C(6)-C(10) 1.539(7) 1.548(5) C(28)-C(32) 1.540(7) 1.539(5)
C(7)-C(8)
C(8)-C(9)
1.553(8) 1.549(6) C(29)-C(30) 1.550(8) 1.547(5)
1.552(7) 1.556(5) C(30)-C(31) 1.557(7) 1.556(5)
C(9)-C(10) 1.531(7) 1.537(5) C(31)-C(32) 1.536(7) 1.537(5)
M-RC(1)
2.100(2) 2.228(2) M-RC(2)
2.097(3) 2.228(2)
a
RC(1) is the ring centroid for the ring defined by the atoms
C1, C2, C3, C4, and C5. RC(2) is the ring centroid for the ring
defined by the atoms C23, C24, C25, C26, and C27. Estimated
standard deviations in the least significant figure are given in
parentheses.
exo,exo-Bis(3-m et h ylisod icyclop en t a d ien yl)t it a n iu m
Dich lor id e (4). A solution of 3-Me (0.94 g, 6.45 mmol) in
dry diethyl ether (20 mL) was prepared according to a previous
paper5a under argon and cooled at -78 °C. To the cold solution
was added 1.2 equiv of n-butyllithium (1.6 M in hexane) via a
syringe, and the mixture was warmed to room temperature
overnight. A white solid appeared. The reaction mixture was
cooled at -78 °C, filtered, and washed with diethyl ether (3 ×
5 mL). The white solid was dried and dissolved in dry
tetrahydrofuran (10 mL). A suspension of TiCl3‚3THF (1.18
g, 3.20 mmol) in dry THF (30 mL) was prepared on which the
solution of the lithium salt was transferred via cannula at
room temperature to give a green coloration. After 4 h of
stirring, carbon tetrachloride (3 mL) was added, affording a
reddish reaction mixture, which was diluted 1.5 h after
addition with methylene chloride/water 1:1 (10 mL). The
aqueous layer was extracted three times with methylene
chloride. The combined organic layers were washed with
water, dried over magnesium sulfate, and evaporated. The
red solid was recrystallized from methylene chloride: yield
0.30 g (23%); mp > 264 °C; MS, m/z (relative intensity), 408-
(68), 373 (12), 263 (28), 145 (100), 130 (18); 1H NMR (CD2Cl2,
599.9 MHz, T ) 263 K) δ ) 5.79 (br s, 4H, peripheral), 3.27
(br s, 4H, bridgehead), 2.11 (s, 6H, Me), 1.79 (br s, 4H, exo-
but this effect causes the catalytic activity of the
complexes in propene polymerization to decrease. This
eventuality may be due to the high steric congestion at
the metal center, which renders more difficult the
approach to the reaction center.
Exp er im en ta l Section
All manipulations were conducted under an argon atmo-
sphere. The solvents were dried and distilled prior to use.
Elemental analyses were performed by the Service de Mi-
croanalyses du L.S.E.O. (Universite´ de Bourgogne). 1H, 13C,
and 31P NMR spectra were recorded with Bruker AC200 and
Varian Unity Plus 600 NMR spectrometers. The activation
(12) (a) Gu¨nther, H. La Spectroscopie de RMN; Masson: Paris,
France, 1993; pp 330-333. (b) Green, M. L. H.; Wong, L.-L. Organo-
metallics 1992, 11, 2660.

Exo,Exo Derivaties of Catalyst Precursors
Organometallics, Vol. 17, No. 22, 1998 4901
Ta ble 5. Selected Bon d An gles (d eg) for 8 a n d 9
angle
8 (M ) Ti)
9 (M ) Zr)
angle
8 (M ) Ti)
9 (M ) Zr)
C(2)-C(1)-C(5)
C(2)-C(1)-C(9)
C(5)-C(1)-C(9)
C(1)-C(2)-C(3)
C(2)-C(3)-C(4)
C(3)-C(4)-C(5)
C(1)-C(5)-C(4)
C(1)-C(5)-C(6)
C(4)-C(5)-C(6)
C(5)-C(6)-C(7)
C(5)-C(6)-C(10)
C(7)-C(6)-C(10)
C(6)-C(7)-C(8)
C(7)-C(8)-C(9)
C(1)-C(9)-C(8)
C(1)-C(9)-C(10)
C(8)-C(9)-C(10)
C(6)-C(10)-C(9)
Cl(1)-M-Cl(2)
108.8(4)
142.3(4)
107.1(4)
108.1(4)
107.3(4)
107.5(4)
108.2(4)
106.8(4)
142.3(4)
103.9(4)
99.9(4)
100.2(4)
103.6(4)
103.5(4)
103.3(4)
100.8(4)
100.2(4)
96.0(4)
108.3(3)
142.8(3)
106.6(3)
107.5(3)
107.9(3)
107.3(3)
109.0(3)
107.1(3)
142.3(3)
103.7(3)
100.3(3)
100.0(3)
103.9(3)
103.4(3)
105.0(3)
100.1(3)
100.5(3)
95.5(3)
C(24)-C(23)-C(27)
C(24)-C(23)-C(31)
C(27)-C(23)-C(31)
C(23)-C(24)-C(25)
C(24)-C(25)-C(26)
C(25)-C(26)-C(27)
C(23)-C(27)-C(26)
C(23)-C(27)-C(28)
C(26)-C(27)-C(28)
C(27)-C(28)-C(29)
C(27)-C(28)-C(32)
C(29)-C(28)-C(32)
C(28)-C(29)-C(30)
C(29)-C(30)-C(31)
C(23)-C(31)-C(30)
C(23)-C(31)-C(32)
C(30)-C(31)-C(32)
C(28)-C(32)-C(31)
RC(1)-M-RC(2)
109.1(4)
141.7(4)
107.6(4)
107.4(4)
107.4(4)
108.0(4)
107.9(4)
106.8(4)
142.2(4)
104.1(4)
99.9(4)
108.3(3)
142.7(3)
106.5(3)
107.7(3)
107.8(3)
107.7(3)
108.5(3)
107.2(3)
142.6(3)
104.1(3)
100.8(3)
99.2(3)
103.9(3)
103.4(3)
104.4(3)
100.1(3)
100.3(3)
95.8(3)
99.8(4)
103.7(4)
103.8(4)
103.3(4)
100.7(4)
99.1(4)
96.3(4)
131.85(9)
91.84(5)
92.94(3)
129.02(5)
2
3
ethano bridge), 1.24 (dt, J HH ) 9.2 Hz, J HH ) 1.5 Hz, 2H,
mixture became brown. After 1.5 h of stirring, the solvent was
evaporated and the solid residue was extracted with toluene
(3 × 10 mL) and washed with pentane (3 × 10 mL). Evapora-
tion of the solvents afforded a solid which was crystallized from
methylene chloride to give 0.40 g (25%) of a brown powder:
mp 263 °C; MS, m/z (relative intensity), 524 (14), 509 (7), 321
(100), 306 (38), 203 (34), 175 (18), 160 (28), 145 (56); 1H NMR
(CD2Cl2, 599.9 MHz, T ) 233 K) δ ) 6.01 (s, 4H, peripheral),
syn-methano bridge), 1.04 (br s, 4H, endo-ethano bridge), 0.74
2
3
(dt, J HH ) 9.2 Hz, J HH ) 1.4 Hz, 2H, anti-methano bridge)
ppm; 1H NMR (CD2Cl2, 599.9 MHz, T ) 243 K) δ ) 5.87, 5.69
(each br s, each 2H, peripheral), 3.34, 3.15 (each br s, each
2H, bridgehead), 2.11 (s, 6H, Me), 1.76 (br s, 4H, exo-ethano
bridge), 1.23 (dt, J HH ) 9.1 Hz, J HH ) 1.5 Hz, 2H, syn-
methano bridge), 1.05, 0.99 (each br s, each 2H, endo-ethano
2
3
2
2
bridge), 0.70 (br d, J HH ) 9.1 Hz, 2H, anti-methano bridge)
3.25 (br s, 4H, bridgehead), 1.79 (d, J HH ) 7.4 Hz, 4H, exo-
2
3
ppm. Coalescence of cyclopentadienyl-H is reached at 262 K,
ethano bridge), 1.30 (dt, J HH ) 9.2 Hz, J HH ) 1.3 Hz, 2H,
∆ν(243 K) ) 105 Hz, ∆Gq(262 K) ) 12.1 ( 0.4 kcal mol-1. Anal.
syn-methano bridge), 1.11 (d, 2J HH ) 9.2 Hz, 2H, anti-methano
bridge), 0.98 (dd, J HH ) 7.4 Hz, J HH ) 2.2 Hz, 4H, endo-
2
3
Calcd for
C
22H26TiCl2 + 0.25CH2Cl2: C, 62.08; H, 6.25.
Found: C, 61.92; H, 6.25.
1
ethano bridge), 0.11 (s, 18H, SiMe3) ppm; H NMR (CD2Cl2,
599.9 MHz, T ) 183 K) δ ) 6.14, 5.83 (each s, each 2H,
exo,exo-Bis(3-m eth ylisod icyclop en ta d ien yl)zir con iu m
Dich lor id e (5). Methylisodicyclopentadienyllithium prepared
as for the titanium complex from 1.45 g (9.91 mmol) of 3-Me
and dissolved in 15 mL of dimethoxyethane (DME) was slowly
added to a suspension of ZrCl4 (1.15 g, 4.93 mmol) in 20 mL
of DME cooled at -20 °C. The mixture was allowed to warm
gradually to room temperature and was refluxed for 48 h. The
solvent was evaporated, and the solid reaction mixture was
extracted with toluene (3 × 10 mL) and washed with pentane
(3 × 10 mL). Evaporation of the solvent gave a brown solid.
Recrystallization from methylene chloride afforded 0.84 g
(19%) of yellow crystals: mp >264 °C; MS, m/z (relative
intensity), 450 (55), 414 (60), 386 (100), 305 (30), 269 (35), 241
(51), 145 (19); 1H NMR (CD2Cl2, 200 MHz, T ) 233 K) δ )
5.85 (s, 4H, peripheral), 3.38 (s, 4H, bridgehead), 2.42 (s, 6H,
peripheral), 3.42, 3.01 (each br s, each 2H, bridgehead), 1.80,
2
1.70 (each br s, each 2H, exo-ethano bridge), 1.26 (d, J HH
)
8.3 Hz, 2H, syn-methano bridge), 0.96 (br s, 4H, endo-ethano
bridge), 0.92 (br s, 2H, anti-methano bridge), 0.05 (br s, 18H,
SiMe3) ppm. Coalescence of bridgehead-H is reached at 198
K, ∆ν(183 K) ) 247 Hz, ∆Gq(198 K) ) 8.7 ( 0.4 kcal mol-1
.
Anal. Calcd for C26H38Si2TiCl2 + 0.25CH2Cl2: C, 57.66; H,
7.10. Found: C, 57.57; H, 6.95.
exo,exo-Bis(3-tr im eth ylsilylisod icyclop en ta d ien yl)zir -
con iu m Dich lor id e (7). Trimethylsilylisodicyclopentadien-
yllithium was prepared as for titanium complex from 1.26 g
(6.17 mmol) of 3-SiMe3 in 40 mL of DME. The solution was
cooled at -40 °C and treated gradually with zirconium
tetrachloride (0.87 g, 3.73 mmol). The mixture was allowed
to warm to room temperature and stirred for 36 h. After this
time, the solvent was evaporated and the residue was ex-
tracted with toluene (3 × 10 mL). Evaporation of the solvent
gave an orange solid. Recrystallization from methylene chlo-
ride afforded 0.55 g (31%) of yellow crystals: decomposition
at 150 °C; MS, m/z (relative intensity), 566 (23), 551 (79), 363
(61), 348 (27), 315 (13), 145 (48). No coalescence is reached
at 183 K. Anal. Calcd for C26H38Si2ZrCl2 + 0.25CH2Cl2: C,
53.43; H, 6.57. Found: C, 53.29; H, 6.59.
2
Me), 1.79 (d, exo-ethano bridge, 4H, J HH ) 7.3 Hz), 1.26 (d,
syn-methano bridge, 2H, 2J HH ) 10.2 Hz), 1.10 (d, endo-ethano
2
bridge, 4H, J HH ) 7.3 Hz), 0.75 (d, anti-methano bridge, 2H,
1
2J HH ) 9.3 Hz) ppm; H NMR (CD2Cl2, 200 MHz, T ) 213 K)
δ ) 6.28, 5.46 (each s, each 2H, peripheral), 3.44, 3.32 (each
s, each 2H, bridgehead), 2.41 (s, 6H, Me), 1.80 (br s, 4H, exo-
2
ethano bridge), 1.26 (d, J HH ) 10.8 Hz, 2H, syn-methano
2
bridge), 1.09 (d, J HH ) 7.3 Hz, 4H, endo-ethano bridge), 0.71
(d, 2J HH ) 9.7 Hz, 2H, anti-methano bridge) ppm. Coalescence
of cyclopentadienyl-H is reached at 231 K, ∆ν(213 K) ) 165
exo,exo-Bis(3-d ip h en ylp h osp h in oisod icyclop en ta d ien -
yl)tita n iu m Dich lor id e (8). A solution of the lithium salt
diphenylphosphinoisodicyclopentadienyllithium (prepared as
for methylisodicyclopentadienyllithium from 0.94 g (2.99
mmol) of 3-P P h 2) in dry THF (10 mL) was transferred via a
cannula at room temperature to a suspension of TiCl3‚3THF
(0.56 g, 1.51 mmol) in dry THF (20 mL) giving a green mixture.
After overnight stirring, carbon tetrachloride (3 mL) was
added, changing the reaction mixture to dark red. After 1.5
h of stirring, the solvent was evaporated and the residue was
extracted with toluene (3 × 10 mL) and then washed with
pentane (3 × 10 mL). Evaporation of the solvents gave a pink
powder. Recrystallization from methylene chloride afforded
Hz, ∆Gq(231 K) ) 10.4 ( 0.4 kcal mol-1
. Anal. Calcd for
C22H26ZrCl2 + 0.25CH2Cl2: C, 56.40; H, 5.64. Found: C, 56.36;
H, 5.80.
exo,exo-Bis(3-tr im eth ylsilylisodicyclopen tadien yl)titan -
iu m Dich lor id e (6). A solution of 3-SiMe3 in dry diethyl
ether (20 mL) was prepared as previously described.5b
A
solution of the lithium salt trimethylsilylisodicyclopenta-
dienyllithium (obtained from 1.26 g (6.17 mmol) of 3-SiMe3)
in dry THF (10 mL) was slowly added at room temperature to
a suspension of TiCl3‚3THF (1.23 g, 3.33 mmol) in dry THF
(30 mL) to give a dark green mixture. After overnight stirring,
carbon tetrachloride (3 mL) was added and the reaction

4902 Organometallics, Vol. 17, No. 22, 1998
Gobley et al.
Ta ble 6. Cr ysta llogr a p h ic Deta ils for 8 a n d 9
0.40 g (36%) of pink crystals: mp 264 °C; MS, m/z (M+) calcd
748.1462, obsd 748.1461, m/z (relative intensity), 713 (76), 433
(17), 398 (32), 315 (100), 185 (43), 108 (46); 31P NMR (81 MHz,
CDCl3) -10.8 ppm; 1H NMR (CD2Cl2, 599.9 MHz, T ) 263 K)
δ ) 7.6-7.0 (m, 20H, Ph), 5.95 (s, 4H, peripheral), 3.32 (s, 4H,
8
9
formula
fw
C44H40Cl2P2Ti‚CH2Cl2 C44H40Cl2P2Zr‚CH2Cl2
834.49
877.81
space group
a, Å
b, Å
P1h (No. 2)
11.126(2)
11.321(2)
18.628(2)
84.73(1)
76.33(1)
62.58(1)
2023.4(5)
2
P1h (No. 2)
11.230(2)
11.337(2)
18.751(1)
84.41(1)
76.008(8)
63.00(1)
2063.8(5)
2
2
bridgehead), 1.90 (d, J HH ) 7.8 Hz, 4H, exo-ethano bridge),
2
1.45 (br s, 2H, syn-methano bridge), 1.30 (d, J HH ) 9.5 Hz,
2
3
c, Å
2H, anti-methano bridge), 1.19 (dd, J HH ) 7.8 Hz, J HH ) 2.2
Hz, 4H, endo-ethano bridge) ppm; 1H NMR (CD2Cl2, 599.9
MHz, T ) 213 K) δ ) 7.49 (4H), 7.29 (12H), 7.04 (4H) (each
m, Ph), 5.94, 5.92 (each s, each 2H, peripheral), 3.36, 3.27 (each
s, each 2H, bridgehead), 1.90 (m, 4H, anti + syn-methano
bridge), 1.33 (m, 4H, exo-ethano bridge), 1.20 (m, 4H, endo-
ethano bridge) ppm. Coalescence of bridgehead-H is reached
at 243 K, ∆ν(213 K) ) 55 Hz, ∆Gq(243 K) ) 11.5 ( 0.4 kcal
mol-1. Anal. Calcd for C44H40P2TiCl2 + 0.5CH2Cl2: C, 67.49;
H, 5.22. Found: C, 67.45; H, 5.33.
R, deg
â, deg
γ, deg
V, Å3
Z
temp, °C
cryst size, mm
density, g/cm-3
(calcd)
23
23
0.15 × 0.15 × 0.42
0.19 × 0.31 × 0.35
1.37
1.41
µ, cm-1
5.84
0.92-1.0
4° e 2θ e 55°
+h, (k, (l
9349 (Rint ) 0.036)
6.34
0.95-1.0
4° e 2θ e 55°
+h, (k, (l
9551 (Rint ) 0.019)
7138
trans factors
2θ limits
data collected
no. of unique data
exo,exo-Bis(3-d ip h en ylp h osp h in oisod icyclop en ta d ien -
yl)zir con iu m Dich lor id e (9). Diphenylphosphinoisodicy-
clopentadienyllithium was prepared as for titanium complex
from 1.89 g (5.97 mmol) of 3-P P h 2 in 40 mL of DME. The
solution was cooled at -40 °C and treated gradually with
zirconium tetrachloride (0.72 g, 3.09 mmol). The reaction
mixture was allowed to warm to room temperature and stirred
for 39 h. After that, the solvent was evaporated and the
residue was extracted with methylene chloride (3 × 10 mL).
The solution so obtained was concentrated to give yellow
crystals: yield 0.80 mg (34%), mp 233 °C; MS, m/z (relative
intensity), 475 (94), 315 (8), 287 (30), 133 (12), 185 (23), 108
(37), 102 (11); 31P NMR (81 MHz, CDCl3) -14.1 ppm; 1H NMR
(CD2Cl2, 200 MHz, T ) 202 K) δ ) 7.27 (br s, 20H, Ph), 5.78
(br s, 4H, peripheral), 3.32 (br s, 4H, bridgehead), 1.88 (br s,
4H, exo-ethano bridge), 1.41 (br s, 4H, anti + syn-methano
bridge), 1.17 (br s, 4H, endo-ethano bridge) ppm; 1H NMR (CD2-
Cl2, 200 MHz, T ) 183 K) δ ) 6.98 (4H), 7.23 (6H), 7.30 (6H),
7.43 (4H) (each br s, Ph), 5.70, 5.87 (each s, each 2H,
peripheral), 3.30, 3.36 (each s, each 2H, bridgehead), 1.87 (br
s, 4H, exo-ethano bridge), 1.42 (br s, 4H, anti + syn-methano
no. of unique data, 5655
with I > 1σ(I)
no. of variables
469
0.066; 0.058
1.83
474
0.042; 0.042
1.65
R(F); Rw(F)a
goodness of fit
R(F) ) ∑||Fo| - |Fc||/∑|Fo| and Rw(F) ) [∑w(|Fo| - |Fc|)2/
a
2
∑w|Fo| ]1/2, with w ) 1/σ2(Fo).
based on the 5655 intensities with I > 1σ(I) and 469 variables
and resulted in final agreement factors of R ) 0.066 and Rw
) 0.058. The final difference electron density map contains
maximum and minimum peaks of 0.75 and -0.66 e/Å3. The
maximum peak is in the vicinity of the solvent molecule. For
both structures neutral atom scattering factors were used16
and include terms for anomalous dispersion.17
X-r a y Cr ysta llogr a p h ic An a lysis of 9. The data collec-
tion crystal was a yellow chunk. Unit cell constants were
obtained by a least-squares fit of the setting angles for 25
reflections in the 2θ range 21-30° (λ(KR1) ) 0.709 30 Å). Of
the six standard reflections measured during the course of data
collection, four decreased slightly in intensity while the other
two increased slightly. Data reduction was done with the
teXsan package,13 and no correction was made for the changes
observed in the standard reflections. A total of 10 041 reflec-
tions were measured by the ω-2θ scan method.
The Zr atom was located by the Patterson method in P1h
(No. 2) using SHELXS-86.14 Phasing on the Zr atom in
DIRDIF18 revealed the remaining non-hydrogen atoms. Full-
matrix least-squares refinements based on F were performed
in teXsan.13 An empirical Ψ-scan absorption correction was
applied to the data.15 There is a disordered solvent molecule
of dichloromethane present in the asymmetric unit. The
disorder was modeled in terms of two positions for the carbon
atom (C(45) and C(46)) and two positions for one of the chlorine
atoms (Cl(4) and Cl(5)). The other chlorine atom, Cl(3),
appears to be ordered. While Cl(4) is considered to be bonded
to C(45) or C(46) in that it makes a reasonable angle with Cl-
(3) and either carbon atom, Cl(5) is only bonded to C(46). The
occupancy factors for C(45) and C(46) were restricted to add
to 1.0, as were those for Cl(4) and Cl(5). Atoms Cl(5), C(45),
and C(46) were refined isotropically, while Cl(3) and Cl(4) were
refined anisotropically. All of the hydrogen atoms were fixed
at calculated positions with C-H ) 0.98 Å. Only one set of
disordered hydrogen atoms was added to dichloromethane.
These were the hydrogens bonded to C(45), and their oc-
cupancy factors were restricted accordingly. The final refine-
ment cycle was based on the 7138 intensities with I > 1σ(I)
2
bridge), 1.18 (d, J HH ) 7.8 Hz, 4H, endo-ethano bridge) ppm.
Coalescence of cyclopentadienyl-H is reached at 200 K, ∆ν-
(183 K) ) 33 Hz, ∆Gq(200 K) ) (9.6 ( 0.4) kcal‚mol-1. Anal.
Calcd for C44H40P2ZrCl2 + 0.85 CH2Cl2: C, 62.27; H, 4.86.
Found: C, 62.20; H, 4.94.
X-r a y Cr ysta llogr a p h ic An a lysis of 8. Data sets for 8
and 9 were measured on a Rigaku AFC5S diffractometer
equipped with graphite-monochromated Mo KR radiation. The
data collection crystal was a dark red rod. Unit cell constants
were obtained by a least-squares fit of the setting angles for
25 reflections in the 2θ range 21-30° (λ(KR1) ) 0.709 30 Å).
During data collection six standard reflections were measured
after every 150 reflections and indicated that the crystal was
stable. Data reduction was done with the teXsan package.13
A total of 9832 reflections were measured by the ω-2θ scan
method.
The structure was solved in P1h (No. 2) by the direct methods
procedure of SHELXS-86.14 Full-matrix least-squares refine-
ments based on F were performed in teXsan.13 An empirical
Ψ-scan absorption correction was applied to the data.15 One
solvent molecule of dichloromethane is present in the asym-
metric unit. The hydrogen atoms were fixed at calculated
positions with C-H ) 0.98 Å. The final refinement cycle was
(13) teXsan, Crystal Structure Analysis Package, version 1.7-2;
Molecular Structure Corporation: The Woodlands, TX, 1995.
(14) SHELXS86: Sheldrick, G. M. Acta Crystallogr. 1990, A46, 467-
473.
(15) North, A. C. T.; Phillips, D. C.; Mathews, F. S. Acta Crystallogr.
1968, A24, 351-359.
(16) Scattering factors for the non-hydrogen atoms are from: Cromer,
D. T.; Waber, J . T. International Tables for X-ray Crystallography; The
Kynoch Press: Birmingham, England, 1974; Vol. IV, Table 2.2A.
Scattering factors for the hydrogen atom: Stewart, R. F.; Davidson,
E. R.; Simpson, W. T. J . Chem. Phys. 1965, 42, 3175-3187.
(17) Creagh, D. C.; McAuley, W. J . International Tables for Crystal-
lography; Kluwer Academic Publishers: Boston, 1992; Vol. C, Table
4.2.6.8.
(18) DIRDIF: Parthasarathi, V.; Beurskens, P. T., Slot, H. J . B. Acta
Crystallogr. 1983, A39, 860-864.

Exo,Exo Derivaties of Catalyst Precursors
Organometallics, Vol. 17, No. 22, 1998 4903
Ta ble 7. Deta ils of th e P olym er iza tion Rea ction s
reaction
temperature
(°C)
duration of the
polymerization
reaction (min)
activity: g of polymer
(g of Zr or Ti)-1
h-1 bar-1
mmol of
catalyst
MAO/Zr
(Ti) ratio
pressure
(bar)
g of polymer
recovered
catalyst
Mη
4
0.046
0.081
0.022
0.024
0.022
0.022
0.029
0.038
0.059
0.017
0.021
0.016
0.019
0.023
0.027
0.043
0.011
0.019
0.013
794
451
872
799
872
872
661
962
619
1128
913
1199
1010
834
1354
850
1744
1010
1476
2
1
2
2
1
1
1
2
1
2
2
2
1
1
2
1
2
2
1
0
-20
+10
0
-20
-40
-50
0
-20
+10
0
-20
-40
-50
0
225
198
180
220
180
157
312
225
192
180
230
180
180
300
210
318
210
155
236
0.121
0.512
2.293
5.626
0.274
0.239
0.249
0.100
0.104
2.693
1.265
5.486
2.734
2.979
0.067
0.122
0.052
0.036
0.065
7
40
211
381
50
50
19
7
11
280
86
633
517
286
7
5
164 000
219 000
6
7
18 500
21 000
47 000
169 000
233 000
8
9
-20
+10
0
11
7
4
-20
14
and 474 variables and resulted in final agreement factors of
R ) 0.042 and Rw ) 0.042. The final difference electron
density map contains maximum and minimum peaks of 0.66
and -0.58 e/Å3. The top six peaks in this map are in the
immediate vicinity of the disordered dichloromethane mol-
ecule. Additional crystallographic details are given in Table
6.
P r op en e P olym er iza tion Rea ction s (Gen er a l P r oce-
d u r e). Rea ction s a t 2 ba r P r op en e P r essu r e. In the
autocave, 20 mL of methylalumoxane (10 wt % in toluene) was
added to 300 mL of dry toluene under argon. The solution
was brought to the desired temperature, and propene was
added to the solution until 2 bar pressure. When the tem-
perature was stable, a solution of the catalyst (10-30 mg) in
toluene (5 mL) was added. After about 3 h of stirring, the
polymerization was stopped by slowly introducing a mixture
of aqueous hydrogene chloride/methanol, 1:1. Stirring was
maintained for 30 min to destroy the excess of reagents. After
several extractions with toluene, the organic layer was washed
with water and the solvent evaporated. The residue was
finally dried under vacuum for 1 day.
P r op en e P olym er iza tion u n d er 1 ba r a t a Tem p er a -
t u r e b elow -20 °C. The experimental procedure was the
same for these polymerizations as it was described above,
excepted that 40-50 mL of propene was condensed into the
autoclave. Details of the polymerization reactions are given
in Table 7.
Su p p or tin g In for m a tion Ava ila ble: Tables of bond
lengths and angles, least-squares planes, positional param-
eters, anisotropic displacement parameters, and calculated
positional parameters for the hydrogen atoms for 8 and 9,
along with one ORTEP drawing for 8 (27 pages). Ordering
information is given on any current masthead page.
OM980542D