Synthesis of zirconium(IV) monocyclopentadienyl-aryloxy complexes and their use in catalytic ethylene polymerization. X-ray structure of (η5-C5Me5)Zr{2,6-OC6H3(CH3)2}3

Article abstract of DOI:10.1021/om000209l

The complex Cp*Zr(2,6-OC₆H₃^tBu₂)Cl₂ (Cp* = η⁵-C₅Me₅) (1) has been prepared by the reaction of the starting material Cp*ZrCl₃ and 1 equiv of the lithium salt of the phenol compound. The reactions of 1 and the appropriate Grignard reagents afford the alkyl derivatives Cp*Zr(2,6-OC₆H₃^tBu₂)Me₂ (2) and Cp*Zr(2,6-OC₆H₃^tBu₂)(Bz)(Cl) (3). This and other dimethyl derivatives, namely, Cp*Zr(2,6-OC₆H₃Me₂)Me₂ (4), Cp*Zr(O-2-^tBu-6-MeC₆H₃)Me₂ (5), and Cp*Zr(O-2-C₃H₅-6-MeC₆H₃)Me₂ (6), can be obtained by reaction of Cp*ZrMe₃ and the corresponding phenol. When an excess of the less bulky 2,6-Me₂C₆H₃OH phenol was used, the completely substituted complex Cp*Zr(2,6-OC₆H₃Me₂)₃ (7) was obtained. The reactivity of Cp*Zr(2,6-OC₆H₃^tBu₂)Me₂ in the insertion process of isocyanide compounds was studied. In all cases, the corresponding η²-iminoacyl compounds, Cp*Zr(2,6-OC₆H₃^tBu₂)(η²-MeC double bond NR)(Me) [R = Xy (8); ⁿBu (9), Cy (10), TMB = 1,1,3,3-tetramethylbutyl (11)], were obtained. Similar reactivity was found for Cp*Zr(2,6-OC₆H₃^tBu₂)(Bz)(Cl) and Cp*Zr(O-2-^tBu-6-MeC₆H₃)Me₂. The complexes were characterized by spectroscopic methods, and in some cases, variable-temperature ¹H NMR spectroscopy studies were carried out. In addition, the molecular structure of Cp*Zr(2,6-OC₆H₃Me₂)₃ has been determined by X-ray diffraction methods. Finally, complexes Cp*Zr(2,6-OC₆H₃^tBu₂)Cl₂ and Cp*Zr(2,6-OC₆H₃Me₂)₃ were tested as ethylene polymerization catalysts in the presence of MAO as cocatalyst. While the former complex shows a high activity similar to that found for classical metallocene catalysts, the latter is much less active. The different activities found for these complexes can be explained in terms of the different activation processes.

Full text of DOI:10.1021/om000209l

Organometallics 2000, 19, 2837-2843
2837
Articles
Syn th esis of Zir con iu m (IV)
Mon ocyclop en ta d ien yl-Ar yloxy Com p lexes a n d Th eir
Use in Ca ta lytic Eth ylen e P olym er iza tion . X-r a y
Str u ctu r e of (η5-C5Me5)Zr {2,6-OC6H3(CH3)2}3
A. Antin˜olo,† F. Carrillo-Hermosilla,† A. Corrochano,† J . Ferna´ndez-Baeza,†
A. Lara-Sanchez,† M. R. Ribeiro,‡ M. Lanfranchi,§ A. Otero,*,† M. A. Pellinghelli,§
M. F. Portela,‡ and J . V. Santos‡
Departamento de Quı´mica Inorga´nica, Orga´nica y Bioquı´mica, Universidad de
Castilla-La Mancha, Campus de Ciudad Real, 13071-Ciudad Real, Spain, and Departamento
de Engenharia Quimica, Instituto Superior Tecnico de Lisboa, Avenue Rovisco Pais,
1096-Lisboa Codex, Portugal, and Dipartimento di Chimica Generale ed Inorganica, Chimica
Analitica, Chimica Fisica, Universita` degli Studi di Parma, Centro di Studio per la
Strutturistica Diffractometrica del CNR, Viale delle Scienze 78, 43100-Parma, Italy
Received March 6, 2000
t
The complex Cp*Zr(2,6-OC6H3 Bu2)Cl2 (Cp* ) η5-C5Me5) (1) has been prepared by the
reaction of the starting material Cp*ZrCl3 and 1 equiv of the lithium salt of the phenol
compound. The reactions of 1 and the appropriate Grignard reagents afford the alkyl
t
t
derivatives Cp*Zr(2,6-OC6H3 Bu2)Me2 (2) and Cp*Zr(2,6-OC6H3 Bu2)(Bz)(Cl) (3). This and
other dimethyl derivatives, namely, Cp*Zr(2,6-OC6H3Me2)Me2 (4), Cp*Zr(O-2-tBu-6-MeC6H3)-
Me2 (5), and Cp*Zr(O-2-C3H5-6-MeC6H3)Me2 (6), can be obtained by reaction of Cp*ZrMe3
and the corresponding phenol. When an excess of the less bulky 2,6-Me2C6H3OH phenol
was used, the completely substituted complex Cp*Zr(2,6-OC6H3Me2)3 (7) was obtained. The
t
reactivity of Cp*Zr(2,6-OC6H3 Bu2)Me2 in the insertion process of isocyanide compounds was
t
studied. In all cases, the corresponding η2-iminoacyl compounds, Cp*Zr(2,6-OC6H3 Bu2)(η2-
n
MeCdNR)(Me) [R ) Xy (8); Bu (9), Cy (10), TMB ) 1,1,3,3-tetramethylbutyl (11)], were
obtained. Similar reactivity was found for Cp*Zr(2,6-OC6H3 Bu2)(Bz)(Cl) and Cp*Zr(O-2-t-
t
Bu-6-MeC6H3)Me2. The complexes were characterized by spectroscopic methods, and in some
1
cases, variable-temperature H NMR spectroscopy studies were carried out. In addition, the
molecular structure of Cp*Zr(2,6-OC6H3Me2)3 has been determined by X-ray diffraction
t
methods. Finally, complexes Cp*Zr(2,6-OC6H3 Bu2)Cl2 and Cp*Zr(2,6-OC6H3Me2)3 were tested
as ethylene polymerization catalysts in the presence of MAO as cocatalyst. While the former
complex shows a high activity similar to that found for classical metallocene catalysts, the
latter is much less active. The different activities found for these complexes can be explained
in terms of the different activation processes.
In tr od u ction
of organometallic chemistry.2 There are many reports
regarding this chemistry that involve metallocene de-
rivatives, but few examples of monocyclopentadienyl
derivatives bearing aryloxy ligands3 have been reported
even though complexes containing titanium as the metal
center have been known for a number of years.3b
Recently, Nomura and co-workers4 described similar
Alkene polymerization by homogeneous metallocene
catalysts has been the object of both fundamental and
applied studies, especially after it was reported that the
presence of partially hydrolyzed trimethylaluminum
(MAO: methylalumoxane) has a favorable effect on the
process.1 Development of new “single-site” group 4
catalyst precursors for optimizing polymerization ca-
talysis is one of the most attractive subjects in the field
(2) Cornils, B., Herrmann, W. A., Eds. Applied Homogeneous
Catalysis with Organometallic Compounds; VCH: Weinheim, 1996.
(3) (a) Steven, J . C.; Neitlamer, D. R. U.S. Patent, 5064, 802, 1991.
(b) Go´mez-Sal, P.; Mart´ın, A.; Mena, M.; Royo, P.; Serrano, R. J .
Organomet. Chem. 1991, 419, 77. (c) Sarsfield, M. J .; Ewart, S. W.;
Tremblay, T. L.; Roszak, A.; Baird, M. C. J . Chem. Soc., Dalton Trans.
1997, 3097. (d) Firth, A. V.; Stephan, D. W. Inorg. Chem. 1998, 37,
4726. (e) Firth, A. V.; Stephan, D. W. Inorg. Chem. 1998, 37, 4732.
(4) Nomura, K.; Naga, N.; Miki, M.; Yanagi, K.; Imai, A. Organo-
metallics 1998, 17, 2152.
† Universidad de Castilla-La Mancha.
‡ Instituto Superior Tecnico de Lisboa.
§ Universita` degli Studi di Parma.
(1) Sinn, H.; Kaminsky, W. Adv. Organomet. Chem. 1980, 18, 99.
10.1021/om000209l CCC: $19.00 © 2000 American Chemical Society
Publication on Web 06/20/2000

2838 Organometallics, Vol. 19, No. 15, 2000
Antin˜olo et al.
Sch em e 2
monocyclopentadienyl derivatives of titanium-contain-
ing bulky disubstituted aryloxy ligands. These com-
plexes play an active role in the polymerization reaction
of R-olefins, such as ethylene, 1-hexene, or propylene,
using MAO as cocatalyst.
Furthermore, many alkyl or hydride derivatives of
group 4 metallocenes are involved in a number of
applications that are of great interest in organic syn-
thesis, including carbon monoxide or isocyanide inser-
tions into metal-hydride or metal-alkyl bonds.5 This
migratory insertion leads to acyl and iminoacyl func-
tions for most of the early d-block metals. In the case of
η2-iminoacyl derivatives, many examples are known
that are more stable than their oxygen counterparts,
especially for complexes that do not contain a Cp ligand.
In fact, alkyl- or aryloxides of the group 4 metals have
been reported6 to react with isocyanides, and such
reactions have enabled the isolation and characteriza-
tion of a large number of η2-iminoacyl derivatives.
In this paper we wish to extend this chemistry to
include the synthesis of zirconium analogues of the type
Cp*Zr(OAr)nX3-n (Cp* ) η5-C5Me5; OAr ) aryloxy
group; X ) halogen, alkyl; n ) 1, 3). The reactivity of
these compounds toward isocyanide insertion and their
use in the catalysis of ethylene polymerization, in the
presence of MAO as a cocatalyst, were also studied.
were isolated as off-white (2) or yellow (3) microcrys-
talline solids that are very air-sensitive. It is interesting
i
to note that the analogous complex Cp*Ti(2,6-OC6H3 -
Pr2)Me2 cannot be obtained by the same procedure
starting from Cp*Ti(2,6-OC6H3 Pr2)Cl2.3 Alternatively,
i
complex 2 could be obtained by the reaction of Cp*ZrMe3
t
with 2,6- Bu2C6H3OH in hexane. This procedure was
extended to other phenols. In this way (see Scheme 2),
complexes Cp*Zr(2,6-OC6H3Me2)Me2 (4), Cp*Zr(O-2-t-
Bu-6-MeC6H3)Me2 (5), and Cp*Zr(O-2-C3H5-6-MeC6H3)-
Me2 (6) were obtained in good yields by reacting 1 equiv
of Cp*ZrMe3 with 1 equiv of the corresponding phenol.
Only when an excess of the less bulky 2,6-Me2C6H3OH
phenol was used was the completely substituted com-
plex Cp*Zr(2,6-OC6H3Me2)3 (7) obtained.
Resu lts a n d Discu ssion
Due to its relative stability and ease of preparation,
complex 2 was chosen to study the reactivity toward
isocyanide insertion at the metal-carbon bonds. This
complex reacted smoothly with 1 equiv of different
isocyanides, namely, XyNC (Xy ) xylyl ) 2,6-Me2C6H3),
nBuNC, CyNC (Cy ) cyclohexyl), or TMBNC (TMB )
1,1,3,3-tetramethylbutyl), to give chiral η2-iminoacyl
derivatives (see below for characterization) Cp*Zr(2,6-
t
Syn th esis. Complex Cp*Zr(2,6-OC6H3 Bu2)Cl2 (1)
was prepared from Cp*ZrCl3 by adding 1 equiv of the
corresponding lithium phenoxide as a hexane/toluene
suspension (see Experimental Section) (Scheme 1).
Sch em e 1
OC6H3 Bu2)(η2-MeCdNR)(Me) [R ) Xy (8); nBu (9), Cy-
t
(10), TMB (11)] (see Scheme 3).
Sch em e 3
Compound 1 was obtained as an air-sensitive yellow
microcrystalline solid that is soluble in dichloromethane,
THF, or toluene, but is scarcely soluble in hexane.
This complex was used as the starting material for
the synthesis of new alkyl derivatives (see Scheme 1).
Thus, the reaction of complex 1 with 2 equiv of MeMgBr
In a similar fashion (see Scheme 3), complexes 3 and
5 reacted with XyNC to give the corresponding η2-
t
in diethyl ether afforded the complex Cp*Zr(2,6-OC6H3 -
Bu2)Me2 (2), whereas the reaction with one or more
t
iminoacyl compounds Cp*Zr(2,6-OC6H3 Bu2)(η2-BzCd
equivalents of BzMgCl afforded the monoalkyl deriva-
NXy)(Cl) (12) and Cp*Zr(O-2-tBu-6-MeC6H3)(η2-MeCd
NXy)(Me) (13). These complexes were synthesized in
order to evaluate the different reactivities of the methyl
(2) and benzyl (3) derivatives toward the insertion
process and also to assess the influence of an asym-
metric bulky aryloxy ligand (5) on the chirality of the
η2-iminoacyl compound.
t
tive Cp*Zr(2,6-OC6H3 Bu2)(Bz)(Cl) (3). The compounds
(5) (a) Collman, P.; Hegedus, L. S.; Norton, J . R.; Finke, R. B.
Principles and Applications of Organotransition Metal Chemistry;
University Science Books: Mill Valley, CA, 1987. (b) Wolczanski, P.
T.; Bercaw, J . E. J . Am. Chem. Soc. 1979, 101, 6450. (c) Evans, W. J .;
Meadows, J . H.; Hunter, E.; Atwood, J . L. Organometallics 1987, 6,
295.
(6) (a) McMullen, A. K.; Rothwell, I. P. J . Am. Chem. Soc. 1985,
107, 1072. (b) Durfee, L. D.; Hill, J . E.; Fanwich, P. E.; Rothwell, I. P.
Organometallics 1990, 9, 75.
These complexes were obtained as off-white (8, 11,
12) microcrystalline solids or as light brown oily materi-

Zr(IV) Monocyclopentadienyl-Aryloxy Complexes
Organometallics, Vol. 19, No. 15, 2000 2839
als (9, 10, 13), all of which are extremely air-sensitive.
A second insertion into the remaining zirconium methyl
group was not observed, even when stoichiometries
other than 1:1 were tested. When carbon monoxide was
used as the reagent in the insertion process, only an
intractable mixture of products was obtained.
Ch a r a cter iza tion . The complexes were character-
1
ized by H NMR, 13C NMR, and IR spectroscopy and
1
elemental analysis (see Experimental Section). The H
NMR spectra of 1 and 2 in CDCl3 show a single peak
near 1.4 ppm, which integrates for 18 protons and
corresponds to the tert-butyl groups of the aryloxy
ligand. A similar spectrum was found for compound 4,
which shows a single peak for the methyl group protons
of the phenoxy substituent. In addition, peaks corre-
sponding to the Cp* ligand and aromatic protons of the
aryloxy group were observed (see Experimental Section).
In contrast, complex 3 shows a very broad peak for the
t
methyl groups of the Bu substituents in its 1H NMR
spectrum at room temperature. This behavior indicates
that for complexes 1, 2, and 4 free rotation about the
O-C bond occurs, while this rotation is partially blocked
in compound 3. To study the dynamic behavior in
solution, variable-temperature 1H NMR experiments
were performed for these complexes. Complexes 1, 2,
F igu r e 1. ORTEP drawing of 7.
Ta ble 1. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for 7
Zr-O(11)
Zr-O(12)
Zr-O(13)
Zr-CEa
Zr-C(1)
Zr-C(2)
1.940(4)
1.947(4)
1.950(4)
2.220(7)
2.525(7)
2.541(7)
Zr-C(3)
2.531(6)
2.516(7)
2.523(7)
1.355(7)
1.359(6)
1.350(7)
Zr-C(4)
Zr-C(5)
t
and 4 show a single peak for the Bu or Me groups of
O(11)-C(11)
O(12)-C(12)
O(13)-C(13)
the aryloxy ligand, even at low temperatures. In con-
trast, complex 3 shows splitting of the broad signal at
low temperature, and this gives rise to two single peaks
at 223 K. When the temperature was raised to 373 K, a
single sharp peak was found for complex 3, indicating
that free rotation had been achieved. The coalescence
temperature (293 K) and the two site exchange equa-
O(11)-Zr-O(12)
O(11)-Zr-O(13)
O(12)-Zr-O(13)
O(11)-Zr-CE
103.29(16)
O(13)-Zr-CE
113.0(2)
167.5(4)
155.3(4)
166.1(5)
105.82(17)
103.54(16)
112.6(2)
C(11)-O(11)-Zr
C(12)-O(12)-Zr
C(13)-O(13)-Zr
O(12)-Zr-CE
117.4(2)
q
a
tions7 can be used to estimate the value of ∆Gc to be
CE is the centroid of the cyclopentadienyl ring
14.5 ( 0.2 kcal mol-1. It is noteworthy that both
complexes 5 and 6, which contain an asymmetric
phenoxy group, show a single peak for their zirconium-
a pseudo mirror plane passing through the Zr atom, the
centroid, and the C(2) and C(7) carbon atoms of the
cyclopentadienyl ring. The phenoxy ligand 2 is quasi-
orthogonal [83.2(3)°], and the other two ligands are
nearly parallel to the pentatomic ring [16.6(2)° and 22.3-
(2)° for 1 and 3, respectively]. The O(11)O(12)O(13)
plane is almost parallel to the Cp ring [2.4(2)°]. Owing
to the orientation of the three phenoxy ligands, an
enlargement of the O(11)-Zr-O(13) and CE-Zr-O(12)
bond angles is observed due to the existence of steric
hindrance between the C(71) and C(73), the C(82) and
C(9), and the C(82) and C(10) methyl carbon atoms. The
two phenoxy ligands related by the pseudo mirror plane
show a Zr-O-C bond angle of nearly 180° [167.5(4)°
and 166.1(5)° for 1 and 3, respectively], whereas for
phenoxy ligand 2 the bond angle is 155.3(4)°. Despite
the difference in the Zr-O-C bond angles, the Zr-O
bond distances are practically equal and are shorter
than those found in several [Cp2Zr(O-Ar)2] or [Cp*2Zr-
(O-Ar)2] complexes.8 As found in these latter complexes,
there is no correlation between the Zr-O bond lengths
and the Zr-O-C bond angles. Howard et al.8 proposed
that the M-O-Ar bond angles do not provide a good
indication of the extent of M-O π-interactions, and it
is most probable that the linearity at the oxygen atom
1
bonded methyl groups in their H NMR spectra over a
wide range of temperatures. This result is in accordance
with free rotation of the phenoxy groups even at low
temperature, a situation that has previously been
described for complexes 1, 2, and 4. Finally, the 1H NMR
spectrum of 7 in C6D6 shows a single peak at 2.24 ppm,
which integrates for 18 protons and can be assigned to
the six equivalent methyl groups of the aryloxy ligands.
This equivalence can again be explained in terms of the
free rotation of these aryloxy groups around the O-C
bonds, even though the metal center is in a more
crowded environment in this case. A single-crystal X-ray
analysis of compound 7 was carried out in order to
provide precise structural details of this compound.
The molecular structure of complex 7 is shown in
Figure 1 together with the atomic labeling scheme. The
second digit of the phenoxy labels refers to moiety 1, 2,
or 3 accordingly. Selected bond distances and angles are
summarized in Table 1. The Zr atom coordinates a Cp*
ring in a η5 and symmetric fashion, as well as three 2,6-
dimethylphenoxy oxygen atoms. The complex presents
a three-legged piano stool coordination and can also be
described as pseudo-tetrahedral if the centroid of the
Cp* ring is considered as occupying one coordination
site. The 2,6-dimethylphenoxy ligand 2 lies roughly on
(7) Abrahams, R. J .; Fisher, J .; Loftus, P. Introduction to NMR
Spectroscopy; J ohn Wiley and Sons: New York, 1988.
(8) Howard, W. A.; Trnka, T. M.; Parkin, G. Inorg. Chem. 1995, 34,
5900, and references therein.

2840 Organometallics, Vol. 19, No. 15, 2000
Antin˜olo et al.
Ta ble 3. Activity in Eth ylen e P olim er iza tion
Ta ble 2
δ
13C NMR (ppm) for
activity
quaternary iminoacyl
carbon atom
complex
Al/Zr T (°C) (kg PE/mol Zr‚h‚bar)
complex
ν(CdN) (cm-1
)
1a
499
503
505
29
40
58
29
29
40
40
25
25
25
25
35
50
25
24
60
2440
2930
2170
4260
4030
3910
2770
3260
28
25
27
34
74
8
9
10
11
12
13
1567
1580
1589
1580
1597
1585
246.55
240.62
238.39
237.84
242.37
239.62
1093
1504
1083
1509
1500
499
1537
1026
508
7b
is attributable mainly to steric interactions.9,10 A com-
parison with other Zr(IV) complexes containing only one
η5-coordinated Cp ring was not possible because, after
a bibliographic search on the Cambridge Structural
Database, we believe that compound 7 is the first
example of this type of complex to be structurally
characterized. In any case, on the basis of the short
Zr-O distances we can propose a strong interaction
between the metal center and the surrounding oxygen
atoms.
The migratory insertion of alkyl groups toward iso-
cyanide ligands allows the introduction of iminoacyl
groups, which are present in different coordination
modes. In fact, for high-valent oxophilic early transition
metals, the iminoacyl group typically adopts a η2-
coordination mode through both the nitrogen and the
carbon atoms.11 Similarly, a η2-coordination mode was
proposed for the iminoacyl ligand in complexes 8-13
on the basis of their IR and 13C NMR spectra. In fact,
these complexes show characteristic11 ν(CdN) stretching
vibrations at ca. 1580 cm-1. In addition, iminoacyl
quaternary carbon atoms resonate at ca. 240 ppm (see
Table 2).
508
2000
1500
c
Cp2ZrCl2
Cp*ZrCl3
5260
82
1240
d
Cp*Ti(Cl)2(O-2,6iPrC6H3)e 2000
a
Experimental conditions: P(ethylene) ) 3.5 bar; 300 mL of
b
toluene; t ) 2.5 min. Experimental conditions: P(ethylene) ) 3.5
bar; 300 mL of toluene; t ) 45 min. c Experimental conditions:
d
P(ethylene) ) 1 bar; 300 mL of toluene; t ) 8 min. Experimental
conditions: P(ethylene) ) 3.5 bar; 300 mL of toluene; t ) 45 min.
e From ref 4.
whereas in complexes 9 and 10 this rotation is free. To
1
confirm this behavior, a variable-temperature H NMR
study was carried out using toluene-d8 as the solvent.
Complexes 8 and 12 do not show any equivalence of the
tert-butyl groups even at 373 K. In contrast, complexes
9 and 10 show a single peak at temperatures as low as
183 K. Complex 11 shows, at 203 K, two peaks corre-
sponding to two inequivalent tBu groups. When the
temperature was raised to 273 K, the peaks coalesced,
q
and at 373 K, a single peak was observed. The ∆Gc
value for the rotation process was estimated to be 14.2
( 0.2 kcal mol-1, which is similar to that found previ-
ously for the blocked rotation of the phenoxy group in
complex 3 (see above). This blocked rotation could be
due to the steric hindrance caused by the bulky imino-
acyl nitrogen substituent (e.g., Xy, TMB) acting on the
aryloxy group.
These complexes contain a chiral center at the zirco-
nium atom, and this results in diastereotopic groups in
9-12, as shown by the NMR spectra (see Experimental
Section). In fact, the 1H NMR spectrum of 9 shows a
complex spin system for the hydrogen atoms of the n-Bu
group, of the type AA′BB′CC′X3; complex 10 shows broad
multiplets for the hydrogen atoms of the cyclohexyl
group; in complex 11 the methyl groups in position 1 of
the TMB group also appear to be diastereotopic, and
the -CH2- group in position 2 leads to a broad peak;
finally, in complex 12 the presence of a diastereotopic
group in the benzyl substituent of the iminoacyl ligand
is also observed.
A remarkable feature of the 1H NMR spectra of these
iminoacyl complexes at room temperature is the differ-
ence observed in the peaks assigned to the tert-butyl
groups of the aryloxy ligand. Whereas complexes 9 and
10 both show a single peak, integrating for 18 protons,
complexes 8 and 12 show two peaks, both of which
integrate for 9 protons, and complex 11 displays a very
broad peak in this region of the spectrum. In addition,
complexes 8 and 12 show two different peaks for the
methyl groups of the xylyl moiety. To explain these
features, we propose that in complexes 8, 11, and 12
the rotation of the phenoxy group about the O-C bond
is partially or totally blocked at room temperature,
As previously mentioned, the presence of a chiral
center allowed us to prepare an iminoacyl complex (13)
with a second center of asymmetry in the phenoxy
group. The aim of this was to observe the two possible
diastereoisomers in the NMR spectra. In fact, complex
13 has, in addition to the zirconium chiral center, a
phenoxy ligand with two different groups at the 2 and
6 positions. If the rotation of the phenoxy group is
blocked, as discussed for complexes 8 and 12, it would
be possible to detect two rotameric diasteroisomers.
Unfortunately, this rotation was not blocked even at 183
K, as was the case for the parent complex 5. However,
a broadening of the signals corresponding to the 2-tBu
and 6-Me substituents was observed at this tempera-
ture, indicating that the rotation is beginning to be
blocked, and thus the two isomers would be observable.
Ca ta lytic Activity in Eth ylen e P olym er iza tion
P r ocesses. The catalytic activity in ethylene polymer-
ization of the aryloxy derivatives 1 and 7, in association
with MAO, was studied, and the results are explained
in terms of the influence of the number of the substit-
uents on the activity. Polymerization reactions were
carried out in the temperature range 25-55 °C and at
several Al/Zr molar ratios. The results are summarized
in Table 3. For comparison, the results obtained by us
(9) (a) Adachi, T.; Hughes, D. L.; Ibrahim, S. K.; Okamoto, S.;
Pickett, C. J .; Yabanouchi, N.; Yoshida, T. J . Chem. Soc., Chem.
Commun. 1995, 1081. (b) Churchill, M. R.; Rotella, F. J . Inorg. Chem.
1978, 17, 668.
(10) Heyn, R. H.; Stephan, D. W. Inorg. Chem. 1995, 34, 2804.
(11) Durfee, L. D.; Rothwell, I. P. Chem. Rev. 1988, 88, 1059.

Zr(IV) Monocyclopentadienyl-Aryloxy Complexes
Organometallics, Vol. 19, No. 15, 2000 2841
isocyanides were purchased from Aldrich and Fluka, stored
over molecular sieves, and deoxygenated before use.
in the presence of the classical Cp2ZrCl2/MAO system
or the monocyclopentadienylzirconium precursor,
Cp*ZrCl3,12 under similar conditions are also reported.
The activity of both new catalytic systems depends
on the Al/Zr ratio, but this effect was much more
pronounced for the system based on complex 1. In this
case, the polymerization activity reaches a maximum
at an Al/Zr ratio near 1000 and then remains constant
or decreases slightly, depending of the reaction temper-
ature. It can be seen from the results in Table 3 that,
at a constant Al/Zr ratio, increasing the temperature
up to 40 °C leads to an increase in the polymerization
rate. This is due to the increase of the propagation rate
with temperature. At higher temperatures a decrease
in the activity was observed, and this is probably related
to the thermal instability of the active species. This is
common behavior for the metallocene systems, and the
optimal temperature for each system depends on the
balance between the propagation rate and the thermal
instability.
1H and 13C NMR spectra were obtained on a 300 Unity
Varian spectrometer. Trace amounts of protonated solvents
were used as references, and chemical shifts are reported in
parts per million relative to SiMe4. IR spectra of iminoacyl
derivatives were obtained in the region 500-4000 cm-1 using
an FT-IR Nicolet Magna Spectra spectrophotometer.
Syn th esis of Cp *Zr (OC6H3(C(CH3)3)2)Cl2 (1). To a solu-
tion of 2,6-di-tert-butylphenol (3.10 g, 15.02 mmol) in 50 mL
of hexane was added a 1.6 M solution of nBuLi in hexane (9.38
mL, 15.02 mmol). A cloudy white precipitate was obtained
immediately. After 2 h of reaction, the liquor was decanted
and the precipitate was filtered off, washed with 50 mL of
hexane, and dried in vacuo. The solid was mixed with Cp*ZrCl3
(5.00 g, 15.02 mmol), and the mixture was suspended in
hexane/toluene (1:1) and stirred, at room temperature, for 4
h. The yellow suspension obtained was dried in vacuo, and
the residue was extracted with 250 mL of hexane. The volume
of the solution was reduced to 25 mL, and it was cooled to
-20 °C for 24 h. Complex 1 was obtained as a light yellow
microcrystalline solid (50%). 1H NMR (300 MHz, C6D6): δ 1.41
(s, 18H, tBu), 2.09 (s, 15H, Cp*), 6.87 (t, J ) 7.93 Hz, 1H, H4),
7.21 (d, J ) 7.93 Hz, 2H, H3 and H5). 13C{1H} NMR (75 MHz,
C6D6): δ 12.57 (Cp*), 31.85 (C(CH3)3), 35.27 (C(CH3)3), 120.98
(C4), 124.83 (C3 and C5), 127.78 (Cp*), 139.23 (C2 and C6),
160.76 (C1). Anal. Calcd for C24H36O3Cl2Zr: C, 57.35; H, 7.22.
Found: C, 57.60; H, 7.46.
For instance, the polymerization activity of the system
based on complex 7 was still increasing at the highest
temperature used (i.e., 50 °C).
In any case, it was also found that polymerization
activity of complex 1 was much higher than that
observed for complex 7 (almost 100 times) and also than
that of the previously described analogous titanium
compound,4 Cp*TiCl2(O-2,6-iPr2C6H3), or the precursor,
Cp*ZrCl3. In contrast, the activity was on the same
order as that of the known Cp2ZrCl2/MAO system (see
Table 3).
The stability of complex 7 could explain the different
deactivation rate found and the decrease of activity
observed for the more thermally unstable system based
on complex 1.
Syn th esis of Cp*Zr (OC6H3(C(CH3)3)2)(CH3)2 (2). Meth od
A. To a solution of Cp*ZrMe3 (0.30 g, 1.10 mmol) in 10 mL of
hexane was added a solution of 2,6-di-tert-butylphenol (0.19
g, 0.94 mmol) in 5 mL of hexane at room temperature. After
stirring for 4 h, the solvent was removed in vacuo and the
residue was extracted with 10 mL of pentane and cooled at
-30 °C for 24 h. Complex 2 was obtained as a white micro-
crystalline solid (91% yield).
t
Meth od B. To a solution of Cp*Zr(OC6H3 Bu2)Cl2 (0.29 g,
0.57 mmol) in 25 mL of diethyl ether, at -80 °C, was added
0.38 mL (1.14 mmol) of a solution of MeMgBr in diethyl ether.
The mixture was stirred for 6 h at room temperature. The
solvent was removed under vacuum, the residue was extracted
with 30 mL of hexane, and, after filtration, the solvent was
Con clu sion s
1
evaporated to afford a white solid (95% yield). H NMR (300
Monocyclopentadienyl-aryloxy derivatives of zirco-
nium can be easily prepared by the reaction of the
appropriate monocyclopentadienyl zirconium trichloride
or trialkyl precursors and lithium phenoxide or phenol.
Alkyl derivatives undergo insertion of one isocyanide
molecule into a zirconium-carbon bond, giving rise to
the corresponding chiral η2-iminoacyl compounds. Simi-
lar reactivity was found for methyl or benzyl zirconium
derivatives. The dynamic behavior of some of these
complexes was studied by means of variable-tempera-
ture 1H NMR studies. The dichloride and triphenoxy
complexes 1 and 7 catalyze ethylene polymerization in
the presence of MAO as cocatalyst. Complex 1, Cp*Zr-
(O-2,6-tBu2C6H3)Cl2, was found to be more active by 100
times than the trisubstituted complex 7, Cp*Zr(O-2,6-
Me2C6H3)3, and 10 times more active than similar
titanium complexes described previously.
t
MHz, C6D6): δ 0.39 (s, 6H, ZrMe), 1.42 (s, 18H, Bu), 1.75 (s,
15H, Cp*), 6.89 (t, 1H, J ) 7.81 Hz, H4), 7.29 (d, 2H, J ) 7.81
Hz, H3 and H5). 13C{1H} NMR (75 MHz, C6D6): δ 11.60 (Cp*),
31.71 (C(CH3)3), 35.22 (C(CH3)3), 45.37 (ZrMe), 120.19 (C3 and
C5), 120.66 (C4), 125.20 (Cp*), 139.11 (C2 and C6), 161.62 (C1).
Anal. Calcd for C26H42OZr: C, 67.62; H, 9.17. Found: C, 67.18;
H, 9.87.
Syn th esis of Cp *Zr (OC6H3(C(CH3)3)2)(CH2P h )(Cl) (3).
To a solution of Cp*Zr(OC6H3(C(CH3)3)2)Cl2 (0.34 g, 0.68 mmol)
in 25 mL of diethyl ether, at -80 °C, was added 0.68 mL (0.68
mmol) of a solution of PhCH2MgCl in diethyl ether. The
mixture was allowed to react at 25 °C for 6 h. The solvent was
removed under vacuum, and the yellow oily residue was
extracted with 40 mL of hexane. After filtration, the solution
was concentrated to 10 mL and cooled at -30 °C overnight to
afford complex 3 as a yellow microcrystalline solid (81% yield).
t
1H NMR (300 MHz, C6D6): δ 1.40 (br s, 18H, Bu), 1.74 (s,
15H, Cp*), 2.55 (AB spin system, 2H, J AB)11.95 Hz, CH2Ph),
6.84 (t, 1H, J ) 7.70 Hz, H4), 7.20 (m, 5H, CH2Ph), 7.38 (d,
2H, J ) 7.70 Hz, H3 and H5). 13C{1H} NMR (75 MHz, C6D6):
δ 12.07 (Cp*), 32.40 (C(CH3)3), 35.60 (C(CH3)3), 72.41 (CH2-
Exp er im en ta l Section
t
Gen er a l P r oced u r es. All reactions were carried out using
Schlenk techniques or a glovebox (model VAC HE-2). Solvents
were distilled from the appropriate drying agents and deoxy-
genated prior to use. Complexes Cp*ZrCl3 and Cp*ZrMe3 were
prepared by literature procedures.12 Different phenols and
Ph), 120.84 (C3 and C5, from C6H3 Bu2), 122.47 (C4, from
t
C6H3 Bu2), 124.37 (C4, from CH2Ph), 125.41 (Cp*), 128.79,
128.94 (C2, C6, C3, C5, from CH2Ph), 138.60 (C1, from CH2Ph),
t
t
145.20 (C2, C6, from C6H3 Bu2), 161.28 (C1, from C6H3 Bu2).
Anal. Calcd for C31H43OClZr: C, 66.69; H, 7.76. Found: C,
66.37; H, 7.52.
(12) Wolczanski, P. T.; Bercaw, J . E. Organometallics 1982, 1, 793.
Syn th esis of Cp *Zr (OC6H3RR′)(CH3)2 [RR′ ) (CH3)2 (4);

2842 Organometallics, Vol. 19, No. 15, 2000
Antin˜olo et al.
R ) CH3, R ′ ) C(CH3)3 (5); R ) CH3, R ′ ) C3H7 (6)].
Complexes 4-6 were synthesized using the method described
for complex 2 (method A) with the corresponding phenol.
ZrMe), 0.80 (t, 3H, J ) 7.30 Hz, CH3(δ), from nBu), 1.15 (m,
n
2H, CH2(γ), from Bu), 1.43 (s, 18H, tBu2), 1.60 (m, 2H, CH2(â),
from nBu), 1.81 (s, 15H, Cp*), 2.16 (s, 3H, MeCdN), 3.46 (m,
2H, CH2(R), from nBu), 6.81 (t, 1H, J ) 7.80 Hz, H4), 7.25 (d,
2H, J ) 7.80 Hz, H3 and H5). 13C{1H} NMR (75 MHz, C6D6):
δ 11.56 (Cp*), 13.89 (CH3(δ)), 19.12 (MeCdN), 20.96 (CH2(γ)),
30.25 (ZrMe), 31.56 (C(CH3)3), 31.68 (CH2(â)), 35.34 (C(CH3)3),
48.02 (CH2(R)), 117.66 (Cp*), 118.82 (C4), 124.93 (C3 and C5),
138.49 (C2 and C6), 162.06 (C1), 240.62 (CdN). Anal. Calcd
for C31H61NOZr: C, 68.32; H, 9.43; N, 2.57. Found: C, 68.77;
H, 9.28; N, 2.69.
1
4: light brown solid, 95% yield. H NMR (300 MHz, C6D6):
δ 0.26 (s, 6H, ZrMe), 1.76 (s, 15H, Cp*), 2.19 (s, 6H, C6H3Me2),
6.82 (t, 1H, J ) 7.61 Hz, H4), 7.10 (d, 2H, J ) 7.61 Hz, H3
and H5). 13C{1H} NMR (75 MHz, C6D6): δ 10.92 (Cp*), 17.54
(C6H3Me2), 38.40 (ZrMe), 119.69 (C3 and C5), 120.46 (C4),
120.69 (Cp*), 128.32 (C2 and C6), 159.10 (C1). Anal. Calcd for
C
20H30OZr: C, 63.60; H, 8.01. Found: C, 63.25; H, 8.45.
1
5: white solid, 95 yield. H NMR (300 MHz, C6D6): δ 0.33
10: 90% yield. 1H NMR (300 MHz, C6D6): δ 0.67 (s, 3H,
ZrMe), 1.10 (m, 2H, CH2(4), from Cy), 1.44 (s, 18H, tBu2), 1.62
(br s, 4H, CH2(3) and CH2(5), from Cy), 1.72 (br s, 2H, CH2(2)
or CH2(6), from Cy), 1.83 (s, 15H, Cp*), 2.01 (br s, 2H, CH2(2)
or CH2(6), from Cy), 2.18 (s, 3H, MeCdN), 3.81 (s, 1H, CH(1),
from Cy), 6.83 (t, 1H, J ) 7.80 Hz, H4), 7.27 (d, 2H, J ) 7.80
Hz, H3 and H4). 13C{1H} NMR (75 MHz, C6D6): δ 11.64 (Cp*),
18.90 (MeCdN), 24.91 (CH2(4)), 25.20, 25.24 (CH2(3) and CH2-
(5)), 29.91 (ZrMe), 31.15 (C(CH3)3), 32.07, 32.95 (CH2(2) and
CH2(6)), 35.36 (C(CH3)3), 60.28 (CH(1)), 117.74 (Cp*), 118.86
(C4), 124.92 (C3 and C5), 138.54 (C2 and C6), 162.07 (C1),
238.39 (CdN). Anal. Calcd for C33H53NOZr: C, 69.41; H, 9.36;
N, 2.45. Found: C, 68.95; H, 9.44; N, 2.72.
t
(s, 6H, ZrMe), 1.49 (s, 9H, Bu), 1.79 (s, 15H, Cp*), 2.10 (s,
3H, Me), 6.87 (pt, 1H, J ) 7.77 Hz, J ) 7.33 Hz, H4), 7.05 (d,
1H, J ) 7.77 Hz, H3 or H5), 7.25 (d, 1H, J ) 7.33 Hz, H3 or
H5). 13C{1H} NMR (75 MHz, C6D6): δ 11.23 (Cp*), 19.09 (Me),
30.47 (C(CH3)3), 34.93 (C(CH3)3), 41.26 (ZrMe), 120.04 (C3 or
C5), 120.63 (C3 or C5), 124.96 (Cp*), 128.74 (C4), 128.78 (C2
or C6), 137.52 (C2 or C6), 159.80 (C1). Anal. Calcd for C23H26
-
OZr: C, 65.81; H, 8.64. Found: C, 65.47; H, 8.31.
1
6: brown oil, 95% yield. H NMR (300 MHz, C6D6): δ 0.25
(s, 6H, ZrMe), 1.77 (s, 15H, Cp*), 2.17 (s, 3H, Me), 3.39 (d,
2H, J ) 6.31, CH2CHdCH2), 5.09 (m, 2H, CH2CHdCH2), 6.06
(m, 1H, CH2CH)CH2), 6.84 (pt, 1H, J ) 7.93 Hz, J ) 7.40 Hz,
H4), 7.01 (d,1H, J ) 7.93 Hz, H3 or H5), 7.07 (d, 1H, J ) 7.40
Hz, H3 or H5). 13C{1H} NMR (75 MHz, C6D6): δ 10.97 (Cp*),
17.79 (Me), 34.91 (CH2CHdCH2), 39.25 (ZrMe), 115.77, 119.73
(C3 and C5), 120.85 (Cp*), 127.28 (CH2CHdCH2), 127.80 (C4),
128.31 (CH2CHdCH2), 128.87, 137.36 (C2 and C6), 158.45
(C1). Anal. Calcd for C22H32OZr: C, 65.45; H, 7.99. Found: C,
65.50; H, 7.67.
11: 90% yield. 1H NMR (300 MHz, C6D6): δ 0.64 (s, 3H,
t
ZrMe), 1.44 (br s, 18H, Bu2), 1.60 (s, 3H, N-C(CH3)2-), 1.83
(s, 15H, Cp*), 1.76 (s, 2H, -CH2-), 2.48 (s, 3H, MeCdN), 6.83
(t, 1H, J ) 7.69 Hz, H4), 7.27 (d, 2H, J ) 7.69 Hz, H3 and
H5). 13C{1H} NMR (75 MHz, C6D6): δ 11.57 (Cp*), 21.96
(MeCdN), 29.75, 30.58 (N-C(CH3)2-), 31.20 (ZrMe), 31.75
(-CH2C(CH3)3), 31.82 (C(CH3)3), 31.89 (-CH2C(CH3)3), 35.32
(C(CH3)3), 54.19 (-CH2-), 68.35 (N-C(CH3)2-), 117.73 (Cp*),
118.72 (C4), 124.91 (C3 and C5), 138.38 (C2 and C6), 162.07
(C1), 237.84 (CdN). Anal. Calcd for C35H59NOZr: C, 69.94;
H, 9.89; N, 2.33. Found: C, 69.53; H, 9.65; N, 2.25.
Syn th esis of Cp *Zr (OC6H3(CH3)2)3 (7). To a solution of
Cp*ZrMe3 (0.15 g, 0.55 mmol) in 10 mL of hexane was added
2,6-dimethylphenol (0.20 g, 1.66 mmol) in 10 mL of hexane.
The mixture was stirred for 3 h to afford a yellow precipitate.
The solid was filtered off, washed with 15 mL of hexane, and
recrystallized from CH2Cl2/hexane to afford complex 7 as a
12: 85% yield. 1H NMR (300 MHz, C6D6): δ 1.41 (s, 9H,
1
t
white microcrystalline solid (87% yield). H NMR (300 MHz,
tBu), 1.61 (s, 9H, Bu), 1.76 (s, 3H, Me from Xy), 1.89 (s, 15H,
C6D6): δ 1.93 (s, 15H, Cp*), 2.24 (s, 18H, OC6H3Me2), 6.75 (t,
3H, J ) 7.33 Hz, H4), 6.93 (d, 6H, J ) 7.33 Hz, H3 and H5).
13C{1H} NMR (75 MHz, C6D6): δ 11.56 (Cp*), 18.30 (OC6H3Me2),
120.88 (C3 and C5), 122.94 (C4), 126.99 (Cp*), 129.42 (C2 and
C6), 159.81 (C1). Anal. Calcd for C34H42O3Zr: C, 69.22; H, 7.18.
Found: C, 69.74; H, 7.08.
Cp*), 2.02 (s, 3H, Me from Xy), 3.97 (AB spin system, 2H, J AB
) 14.65 Hz, CH2Ph), 7.27 (m, 2H, H4). 13C{1H} NMR (75 MHz,
C6D6): δ 11.92 (Cp*), 19.39, 19.42 (Me from Xy), 32.32, 32.77
(C(CH3)3), 35.66, 35.74 (C(CH3)3), 44.82 (CH2Ph), 120.10,
122.64, 125.05, 125.44, 126.00, 127.22, 128.61 (C3, C4, C5 from
t
C6H3 Bu2 and Xy, and from Cp*), 122.84 (C4, CH2Ph), 128.10,
128.40 (C2 or C6, C3 or C5, CH2Ph), 134.40 (C1, CH2Ph),
129.76, 130.49 (C2 and C6, Xy), 138.60, 139.90 (C2 and C6,
Syn th esis of Cp *Zr (OC6H3RR′)(R′′CdNX)(Y) [R ) R′ )
tBu , X ) Y ) Me, R′′ ) Xy (8), n Bu (9), Cy (10), TMB (11);
t
t
t
t
C6H3 Bu2), 144.37 (C1, Xy), 161,63 (C1, C6H3 Bu2), 242.37 (Cd
N). Anal. Calcd for C40H52NOClZr: C, 69.68; H, 7.60; N, 2.03.
Found: C, 69.30; H, 7.44; N, 1.98.
R ) R′ ) Bu , X ) CH2P h , Y ) Cl, R′′ ) Xy (12); R ) Bu ,
R′ ) Me, X ) Y ) Me, R′′ ) TMB (13)]. To a solution of
Cp*Zr(OC6H3RR′)(X)(Y) (0.60 mmol) in 5 mL of hexane was
added a solution of the corresponding isocyanide, RNC (0.60
mmol), in 5 mL of hexane. The solution was stirred at room
temperature for 5 h, and the solvent was removed under
vacuum. Complexes 8, 11, and 12 were obtained as off-white
solids after recrystallization from pentane. Complexes 9, 10,
and 13 were obtained as spectroscopically pure light-brown
oily materials after several attempts at recrystallization.
8: 90% yield. 1H NMR (300 MHz, C6D6): δ 0.53 (s, 3H,
ZrMe), 1.42 (s, 9H, tBu), 1.52 (s, 9H, tBu), 1.62 (s, 3H, Me from
Xy), 1.86 (s, 15H, Cp*), 2.09 (s, 3H, Me from Xy), 2.0.11 (s,
13: 90% yield. 1H NMR (300 MHz, C6D6): δ 0.51 (s, 3H,
ZrMe), 0.89 (s, 9H, -CH2C(CH3)2), 1.40 (s, 3H, N-C(CH3)2-),
t
1.46 (s, 3H, N-C(CH3)2-), 1.51 (s, 9H, Bu), 1.73 (AB spin
system, 2H, J AB ) 14.65 Hz, -CH2-), 1.96 (s, 15H, Cp*), 2.14
t
(s, 3H, C6H3 Bu2), 2.55 (s, 3H, MeCdN), 6.79 (pt, 1H, J ) 7.81
Hz, J ) 7.33 Hz, H4), 7.04 (d, 1H, J ) 7.33 Hz, H3 or H5),
7.21 (d, 1H, J ) 7.81 Hz, H3 and H5). 13C{1H} NMR (75 MHz,
t
C6D6): δ 11.36 (Cp*), 19.29 (C6H3 Bu2), 22.04 (MeCdN), 27.91
(ZrMe), 30.51, 30.81 (N-C(CH3)2-), 31.61 (C(CH3)3), 31.90
(-CH2C(CH3)2), 32.06 (-CH2C(CH3)3), 35.02 (C(CH3)3), 53.74
(-CH2-), 67.80 (N-C(CH3)2-), 117.46 (Cp*), 118.99, 124.78 (C3
and C5), 127.17 (C4), 128.63, 136.93 (C2 and C6), 160.54 (C1),
239.62 (CdN). Anal. Calcd for C32H50NOZr: C, 68.76; H, 9.56;
N, 2.51. Found: C, 68.36; H, 9.73; N, 2.38.
t
3H, MeCdN), 6.90 (m, 4H, H3 and H5, from C6H3 Bu2 and
t
Xy), 7.26 (dd, 1H, J ) 5.10 Hz, J ) 4.40 Hz, H4 from C6H3 -
Bu2 or Xy), 7.30 (dd, 1H, J ) 4.80 Hz, H)5.60 Hz, H4 from
C6H3 Bu2 or Xy). 13C{1H} NMR (75 MHz, C6D6): δ 11.92 (Cp*),
t
18.91, 19.09 (Me from Xy), 22.10 (MeCdN), 32.79 (ZrMe),
Sin gle-Cr ysta l X-r a y Diffr a ction Exp er im en ta l Da ta .
Details of the crystal data and a summary of data collection
parameters for compound 7 are given in Table 4. Data were
collected on a Philips PW 1100 diffractometer using graphite-
monochromated Mo KR radiation. A set of 24 carefully centered
reflections in the range 7.0° < θ < 12.4° was used for
determining the lattice constants. No decay was observed
during the data collection. The data were corrected for Lorentz
and polarization effects. The structure was solved by direct
31.81, 32.45 (C(CH3)3), 35.40, 35.52 (C(CH3)3), 118.50, 119.34,
t
125.30, 125.40, 125.73, 128.19, 128.31 (C3, C4, C5 from C6H3 -
Bu2 and Xy, and from Cp*), 129.03, 131.14 (C2 and C6 from
t
Xy), 138.51, 139.02 (C2 and C6 from C6H3 Bu2), 144.72 (C1
t
from Xy), 161.73 (C1 from C6H3 Bu2), 246.55 (CdN). Anal.
Calcd for C35H51NOZr: C, 70.89; H, 8.67; N, 2.36. Found: C,
69.42; H, 9.15; N, 2.33.
9: 90% yield. 1H NMR (300 MHz, C6D6): δ 0.56 (s, 3H,

Zr(IV) Monocyclopentadienyl-Aryloxy Complexes
Organometallics, Vol. 19, No. 15, 2000 2843
Ta ble 4. Cr ysta l Da ta a n d Str u ctu r e Refin em en t
for 7
was used without further purification as received from Witco
GmbH. Ethylene polymerizations were carried out in a 1 L
glass autoclave reactor. Toluene was used as solvent, and the
reaction time, monomer pressure, and the amount of catalyst
introduced were chosen carefully in order to avoid mass
transfer limitations. In a typical procedure, ethylene was first
introduced into the reactor at the polymerization temperature
until saturation of toluene was achieved. The prescribed
amount of zirconium complex precatalyst and MAO were first
mixed and allowed to react during 15 min. The mixture was
then introduced into the reaction vessel, in a nitrogen stream,
and the polymerization was started. Ethylene pressure and
temperature were recorded at different polymerization times.
The polymerization rate was calculated by measuring the
pressure drop. The use of an ethylene reservoir (14 L volume)
ensured a final ethylene pressure drop of less than 5% in order
to maintain a constant monomer concentration.
empirical formula
fw
C34H42O3Zr
589.90
temperature
293(2) K
wavelength
0.71073 Å
cryst syst, space group
unit cell dimens
monoclinic, P21/ n
a ) 15.935(5) Å
b ) 22.262(8) Å
c ) 8.645(3) Å
â ) 91.44(2)°
volume
Z, calcd density
abs coeff
3066(2) Å3
4, 1.278 Mg/m3
0.389 mm-1
F(000)
1240
cryst size
θ range for data collection
index ranges
0.18 × 0.25 × 0.28 mm
3.03-24.00°
-18 e h e 18, 0 e k e 25,
0 e l e 9
The tests were performed twice, and the results were in well
agreement, with differences less than 5%. The average values
were showed in Table 3.
no. of reflns collected/unique
refinement method
5134/4791 [R(int) ) 0.0943]
full-matrix least-squares on F2
4791/0/354
no. of data/restraints/params
goodness-of-fit on F2a
0.705
Ack n ow led gm en t. A.A.G., F.C.H., A.C., J .F.B., and
A.O. gratefully acknowledge financial support from the
Acciones Integradas Hispano-Portuguesas, Spain (HP
97-0036) and the Direccio´n General de Ensen˜anza
Superior e Investigacio´n Cient´ıfica, Spain (Grant No.
PB95-0023-C01-02). M.R.R., J .V.S., and M.F.P. grate-
fully acknowledge financial support from the Conselho
de Reitores Universidades Portuguesas (Acc¸o˜es Integra-
das Luso-Espanholas LE-25/98), Fundac¸a˜o para a Cien-
cia e Tecnologia (Project Praxis PCEX/C/QUI/75/96), and
the sub-Programa Cieˆncia e Tecnologia do 2° Quadro
Comunita´rio de Apoio for Grant BD13551/97. M.L. and
M.A.P. gratefully acknowledge financial support from
the Ministero dell’Universita` e della Ricerca Scientifica
e Tecnologica (MURST) and Consiglio Nazionale delle
Ricerche (CNR, Rome, Italy).
final R indices [I > 2σ(I)]
R indices (all data)
largest diff peak and hole
R1 ) 0.0392, wR2 ) 0.0427
R1 ) 0.2111, wR2 ) 0.0731
0.313 and -0.399 e‚Å-3
GOOF ) [∑[w(Fo2 - Fc2)2]/(n - p)]1/2, R1 ) ∑||Fo| - |Fc||/∑|Fo|,
a
wR2 ) [∑[w(Fo - Fc2)2]/∑[w(Fo2)2]]1/2, w ) 1/[σ2(Fo2) + (aP)2
+
2
bP], where P ) [max(Fo2,0) + 2Fc2]/3.
methods (SIR-92)13 and refined anisotropically for all non-
hydrogen atoms by full-matrix least-squares on F2 using the
SHELXL-97 program.14 All the hydrogen atoms were geo-
metrically fixed using the riding model. All calculations were
carried out on the Digital AlphaStation 255 of the “Centro di
Studio per la Strutturistica Diffrattometrica” del CNR, Parma.
The programs PARST15 and ORTEP16 were also used.
P olym er iza tion Test. Reactions were carried out under a
controlled atmosphere. High-purity ethylene (Air Liquide) was
purified over 3A and 13A molecular sieves. Methylalumoxane
Su p p or tin g In for m a tion Ava ila ble: Crystal structure
data for 7, including tables of atomic positional parameters,
anisotropic thermal parameters, full listing of bond dis-
tances and angles, and hydrogen atomic coordinates. The
material is available free of charge via the Internet at
http://www.pubs.acs.org.
(13) Altomare, A.; Cascarano, G.; Giacovazzo, C.; Gualiardi, A.;
Burla, M. C.; Polidori, G.; Camalli, M. J . Appl. Crystallogr. 1994, 27,
435.
(14) Sheldrick, G. M., SHELXL-97, Program for the refinement of
crystal structures; University of Go¨ttingen, 1997.
(15) Nardelli, M. Comput. Chem. 1983, 7, 95.
(16) Zolnai, L.; Pritzkow, H. ZORTEP. ORTEP original program
modified for PC, University of Heidelberg, 1994.
OM000209L