Ancillary aryloxide ligands in ethylene polymerization catalyst precursors

Article abstract of DOI:10.1016/S0022-328X(99)00422-2

The compounds CpTiCl₂(OC₆H₃-i-Pr₂) (1), CpTiCl(OC₆H₃-i-Pr₂)₂ (2), CpTi(R)(OC₆H₃-i-Pr₂)₂ (R=t-Bu 3, s-Bu 4, n-Bu 5, Me 6) have been prepared and characterized. Compounds 1 or 2 in the presence of 500 equivalents of methylaluminoxane (MAO) act as catalyst precursors for ethylene polymerization. While the catalysts derived from the monocyclopentadienyl complexes are much less active that the metallocenes, there is a clear enhancement in the activity of about 40% as a result of the inclusion of a second aryloxide ligand. Reactions of 1 with AlMe₃ revealed stepwise formation of CpTi(Me)Cl(OC₆H₃-i-Pr₂) 7 and CpTi(Me)₂(OC₆H₃-i-Pr₂) 8, while subsequent addition of AlMe₃ afforded complete conversion to 8, with formation of the aluminum species [AlMe₂(OC₆H₃-i-Pr₂)]_n 9. In contrast, the catecholate complex CpTi(O₂C₆H₄)Cl 10 reacts with AlMe₃ yielding the paramagnetic species [CpTi(O₂(C₆H₄))·AlClMe₂] ₂ 11. Incorporation of aryloxide ligands in modified metallocenes was readily accomplished with the preparation of Cp₂ZrCl(OC₆H₃-i-Pr₂) 12, Cp₂ZrCl(OC₆H₅) 13, Cp₂ZrMe(OC₆H₅) 14 and Cp₂TiCl(OC₆H₃-i-Pr₂) 15. In combination with MAO, 12, 14 and 15 effect the polymerization of ethylene with an 11% increase in activity over the parent metallocenedichlorides. The implications of the increased activity are considered. Crystallographic data are reported for 2, 3, 6, 9, 11, 12 and 13.

Full text of DOI:10.1016/S0022-328X(99)00422-2

www.elsevier.nl/locate/jorganchem
Journal of Organometallic Chemistry 591 (1999) 185–193
Ancillary aryloxide ligands in ethylene polymerization catalyst
precursors
Andrea V. Firth, Jeffrey C. Stewart, Aaron J. Hoskin, Douglas W. Stephan *
School of Physical Sciences, Chemistry and Biochemistry, Uni6ersity of Windsor, Windsor, ON Canada N9B 3P4
Received 18 May 1999; accepted 7 July 1999
Abstract
The compounds CpTiCl2(OC6H3-i-Pr2) (1), CpTiCl(OC6H3-i-Pr2)2 (2), CpTi(R)(OC6H3-i-Pr2)2 (R=t-Bu 3, s-Bu 4, n-Bu 5, Me
6) have been prepared and characterized. Compounds 1 or 2 in the presence of 500 equivalents of methylaluminoxane (MAO) act
as catalyst precursors for ethylene polymerization. While the catalysts derived from the monocyclopentadienyl complexes are
much less active that the metallocenes, there is a clear enhancement in the activity of about 40% as a result of the inclusion of
a second aryloxide ligand. Reactions of 1 with AlMe3 revealed stepwise formation of CpTi(Me)Cl(OC6H3-i-Pr2) 7 and
CpTi(Me)2(OC6H3-i-Pr2) 8, while subsequent addition of AlMe3 afforded complete conversion to 8, with formation of the
aluminum species [AlMe2(OC6H3-i-Pr2)]n 9. In contrast, the catecholate complex CpTi(O2C6H4)Cl 10 reacts with AlMe3 yielding
the paramagnetic species [CpTi(O2(C6H4))·AlClMe2]2 11. Incorporation of aryloxide ligands in modified metallocenes was readily
accomplished with the preparation of Cp2ZrCl(OC6H3-i-Pr2) 12, Cp2ZrCl(OC6H5) 13, Cp2ZrMe(OC6H5) 14 and Cp2TiCl(OC6H3-
i-Pr2) 15. In combination with MAO, 12, 14 and 15 effect the polymerization of ethylene with an 11% increase in activity over
the parent metallocenedichlorides. The implications of the increased activity are considered. Crystallographic data are reported for
2, 3, 6, 9, 11, 12 and 13. © 1999 Elsevier Science S.A. All rights reserved.
Keywords: Cyclopentadienyl; Titanium; Aryloxide; Ethene polymerization
has received limited attention [20]. We have recently
described the chemistry of thiolate derivatives of Cp-
Ti(aryloxide) complexes [21–23]; however, it is only in
very recent work that Nomura et al. [24] and Repo et
al. [25] have examined the utility of some of these
species in olefin polymerization catalysis. In this paper,
we describe the synthesis, chemistry and olefin polymer-
ization catalysis for several related half-sandwich
derivatives containing aryloxide ligands. The lessons
learned from the studies of these systems are then
applied to metallocene derivatives to effect enhanced
catalytic activity.
1. Introduction
The utility of metallocenes in olefin polymerization
has spawned a variety of approaches to the develop-
ment of new catalysts. Many have studied metallocene
derivatives [1–9] or analogs [10–13], while others have
examined half-sandwich complexes such as the so-called
‘constrained geometry catalysts (CGC)’ of the form
(C5Me4SiR2NR)MX2 [14–16]. Still others have adopted
the approach based on new catalysts derived from
complexes not containing cyclopentadienyl ligands [17–
19]. One of our approaches involves the systematic
study of a series of less active compounds, with a view
to uncovering structural features that can be incorpo-
rated into known, highly active systems. In these efforts
we began with a focus on the inclusion of ancillary
aryloxide ligands. In general, the study of catalysts
based on half-sandwich complexes (other than CGC)
2. Experimental
2.1. General data
All preparations were done under an atmosphere of
dry, O2-free N2 employing both Schlenk line techniques
and an Innovative Technologies or Vacuum Atmo-
* Corresponding author. Fax: +1-519-9737098.
E-mail address: stephan@uwindsor.ca (D.W. Stephan)
0022-328X/99/$ - see front matter © 1999 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(99)00422-2

186
A.V. Firth et al. / Journal of Organometallic Chemistry 591 (1999) 185–193
spheres inert atmosphere glove box. Solvents were
reagent grade, distilled from the appropriate drying
agents under N2 and degassed by the freeze–thaw
method at least three times prior to use. 1H- and
13C{1H}-NMR spectra were recorded on a Bruker
Avance-300 and 500 operating at 300 and 500 MHz for
1H spectra, respectively. Trace amounts of protonated
solvents were used as references and chemical shifts are
reported relative to SiMe4. EPR spectra were recorded
employing a Bruker EPS 300e spectrometer equipped
with a nuclear magnetometer and a HP frequency
counter. Low- and high-resolution EI mass spectral
data were obtained employing a Kratos Profile mass
spectrometer outfitted with a N2 glove bag enclosure
for the inlet port. Galbraith Laboratories, Knoxville,
TN or Schwarzkopf Laboratories, Woodside, NY per-
formed combustion analyses. The compound CpTiCl3
was purchased from Strem Chemicals. The compounds
Cp2ZrMeCl [26], CpTiCl2Me [27], CpTiCl2(OC6H3-i-
Pr2) 1 [28] and CpTiCl(O2C6H4) 10 [29] were prepared
via known methods.
(CH(CH3)2), 25.3 (CH(CH3)2), 33.5 (TiꢀC(CH3)3), 82.2
(TiꢀC(CH3)), 115.0 (Cp), 121.3 (Ar), 123.0 (Ar), 137.0
(o-Ar), 160.5 (ipso-Ar). HRMS for C33H48TiO2
524.3134; Found: 524.3155; Anal. Calc.: C: 75.55; H:
1
9.22; Found: C:75.29; H: 9.02. 4: Yield 40%, H-NMR
(C6D6, 25°C)l: 1.15–1.2 (m,27H, CH(CH3)2,
CH(CH2CH3)(CH3)3), 1.45 (d, 3H, ꢀJHꢀHꢀ=7 Hz,
CH(CH2CH3)(CH3), 2.10 (d of t, 2H, ꢀJHꢀHꢀ=7 Hz,
CH(CH2CH3)(CH3)), 2.61 (t of quart, 1H, ꢀJHꢀHꢀ=7
Hz, CH(CH2CH3)(CH3), 3.47 (sept, 2H, ꢀJHꢀHꢀ=7 Hz,
CH(CH3)2), 3.57 (sept, 2H, ꢀJHꢀHꢀ=7Hz, CH(CH3)2),
6.17 (s, 5H, Cp), 6.90–6.93 (m, 2H, Ar), 7.02–7.06 (m,
4H, Ar). 13C{1H}-NMR (C6D6, 25°C)l: 22.9
(CH(CH2CH3)(CH3)), 24.1 (CH(CH3)2), 24.2 (CH-
(CH3)2), 24.4 (CH(CH3)2), 24.5 (CH(CH3)2), 26.7
(CH(CH2CH3)(CH3)),
27.1
((CH(CH3)2)
(27.4,
CH(CH3)2, 33.9 (CH(CH2CH3)(CH3)), 87.3 (CH(CH2-
CH3)(CH3)), 115.0 (Cp), 119.0 (Ar), 122.2 (Ar), 138.1
(o-Ar), 163.3 (ipso-Ar). HRMS for C33H48TiO2:
524.3134, Found: 524.3138. 5: Yield 53%; 1H-NMR
(C6D6, 25°C) l: 1.23–1.25 (m, 29H, CH(CH3)2 and
CH2CH2CH2CH3) 1.98 (m, 4H, CH2CH2CH2CH3),
3.49 (sept, 4H, ꢀJHꢀHꢀ=7 Hz, CH(CH3)2), 6.05 (s, 5H,
Cp), 6.95 (t, 2H, ꢀJHꢀHꢀ=7 Hz, p-Ar), 7.07(d, 4H,
ꢀJHꢀHꢀ=7 Hz, m-Ar). 13C{1H}-NMR (C6D6, 25°C) l:
12.9 (CH2CH2CH2CH3), 23.2 (CH(CH3)2), 25.8
(CH(CH3)2), 27.1 (CH2CH2CH2CH3), 35.3 (CH2CH2-
CH2CH3), 72.7 (CH2CH2CH2CH3), 113.7 (Cp),
121.2(Ar), 122.8 (Ar), 136.7 (o-Ar), 160.4 (ipso-Ar).
HRMS for C33H48TiO2: 524.3134, Found: 524.3136. 6:
Yield 63%; 1H-NMR (C6D6, 25°C) l: 1.21 (d, 12H,
ꢀJHꢀHꢀ=7 Hz, CH(CH3)2), 1.22 (d, 12H, ꢀJHꢀHꢀ=7 Hz,
CH(CH3)2), 1.39 (s, 3H, TiꢀCH3), 3.50 (sept, 4H,
ꢀJHꢀHꢀ=7 Hz, CH(CH3)2), 6.03 (s, 5H, Cp), 6.95 (t, 2H,
ꢀJHꢀHꢀ=7 Hz, p-Ar), 7.07 (d, 4H, ꢀJHꢀHꢀ=7 Hz, m-Ar).
13C{1H}-NMR (C6D6, 25°C) l: 23.0 (CH(CH3)), 23.8
(CH(CH3)), 26.6 (CH(CH3)), 48.0 (TiꢀCH3), 114.6
(Cp), 122.0 (Ar), 123.3 (Ar), 137.4 (o-Ar), 161.4 (
2.2. Synthesis of CpTiCl(OC6H3-i-Pr2)2 (2)
To CpTiCl3(2.18 g, 10 mmol) suspended in benzene
was added HOC6H3-i-Pr2 (3.56 g, 20 mmol) and imida-
zole (1.26 g, 20 mmol). The reaction mixture was stirred
overnight, then filtered after which the solvent was
removed. Orange crystals were obtained in 86% yield
1
from hexane. H NMR (C6D6, 25oC) l: 1.22 (d, 12H,
ꢀJHꢀHꢀ=7 Hz, CH(CH3)2), 1.26(d, 12H, ꢀJHꢀHꢀ=7 Hz,
CH(CH3)2), 3.69 (sept, 4H, ꢀJHꢀHꢀ=7 Hz, CH(CH3)2),
6.19 (s, 5H, Cp), 6.96(t, 2H, ꢀJHꢀHꢀ=7 Hz, p-Ar), 7.05
(d, 4H, ꢀJH–Hꢀ=7 Hz, m-Ar). 13C{1H}-NMR (C6D6,
25°C) l: 22.9 (CH(CH3)2), 23.3 (CH(CH3)2),
25.9(CH(CH3)2), 117.8 (Cp), 122.7(Ar), 122.8(Ar),
137.0(o-Ar), 162.9(ipso-Ar). HRMS for C29H39TiO2Cl:
502.2118, Found: 502.2120; Anal. Calc.: C: 69.25; H:
7.82; C: 69.15; H: 7.69.
ipso-Ar).
HRMS
for
C30H42TiO2:
482.2664
Found:482.2663; Anal. Calc.: C: 74.67; H: 8.77; Found:
C: 74.55; H: 8.71.
2.3. Synthesis of CpTiR(OC6H3-i-Pr2)2, R=t-Bu 3,
s-Bu 4, n-Bu 5, Me 6
These compounds were prepared in a similar manner
and thus only one representative preparation is de-
scribed. To 2 (95 mg, 0.19 mmol) dissolved in hexane
was added t-BuLi drop wise (111.7 ml of a 1.7 M
solution, 0.19 mmol). The reaction mixture was stirred
for a few minutes, then filtered, after which the solvent
was reduced. Orange crystals were obtained in 40%
yield. 3: 1H-NMR (C6D6, 25°C)l: 1.19 (d, 12H,
ꢀJHꢀHꢀ=7 Hz, CH(CH3)2), 1.22 (d, 12H, ꢀJHꢀHꢀ=7 Hz,
CH(CH3)2), 1.48(s, 9H, TiꢀC(CH3)3), 3.67 (sept, 4H,
ꢀJHꢀHꢀ=7 Hz, CH(CH3)2), 6.18 (s, 5H, Cp), 6.96 (t, 2H,
ꢀJHꢀHꢀ=7Hz, p-Ar), 7.07 (d, 4H, ꢀJHꢀHꢀ=7 Hz, m-Ar).
13C{1H}-NMR (C6D6, 25°C)l: 23.6 (CH(CH3)2), 23.9
2.4. Synthesis of CpTi(Me)Cl(OC6H3-i-Pr2) (7)
(i) To a solution of CpTiCl2Me (90 mg, 0.45 mmol)
in benzene was added Li(OC6H3-2,6-i-Pr2) (85 mg, 0.45
mmol). The reaction was stirred for 1 h at 25°C and
then filtered. The benzene was removed and a yellow
solid was crystallised from hexane. (ii) An alternative
synthesis of 7 is achieved via the reaction of 1 (200 mg,
0.51 mmol) with ZnMe2 (140 ml of a 2 M solution, 0.28
mmol) in benzene (0.5 ml). The mixture was stirred at
25°C overnight and the solvent removed. The residue
was extracted into hexane, filtered and the solvent
removed to give the yellow solid in 80% yield. 1H-NMR

A.V. Firth et al. / Journal of Organometallic Chemistry 591 (1999) 185–193
187
(C6D6, 25°C)l: 1.17(d, 6H, ꢀJHꢀHꢀ=7 Hz, CH(CH3)2),
1.23 (d, 6H, ꢀJHꢀHꢀ=7 Hz CH(CH3)2), 1.48 (s, 3H,
TiCH3), 3.28 (sept, 2H, ꢀJHꢀHꢀ=7 Hz, CH(CH3)2), 5.93
(s, 5H, Cp), 6.8–6.95 (m, br, 3H, Ar). 13C{1H}-NMR
(C6D6, 25°C) l: 23.4 (CH(CH3)2), 23.5 (CH(CH3)2),
26.9 (CH(CH3)2), 61.6 (TiꢀCH3) 116.2 (Cp), 123.3
(Ar), 123.4 (Ar), 137.9 (o-Ar), 162.1 (ipso-Ar). Anal.
Calc. for C18H25ClOTi: C: 63.45; H: 7.40; Found: C:
63.25; H: 7.19.
[CpTi(OC6H4O)·AlClMe2]2 were isolated in 73% yield.
EPR (C6H6): g=1.979. HRMS for C26H30Ti2O4Cl2Al2:
594.0212, Found: 594.0239. Calc.: C:49.79; H:4.82;
Found: C: 49.59; H: 4.73.
2.9. Synthesis of Cp2ZrCl(OC6H3-i-Pr2) (12) and
Cp2ZrCl(OC6H5) (13)
These compounds were prepared in a similar fashion
and thus one representative preparation is presented.
To Cp2ZrHCl (100 mg 0.39 mmol) in benzene was
added HOC6H3-i-Pr2 (89 mg, 0.5 mmol). Gas evolution
was apparent immediately. After 2 h, the solvent vol-
ume was reduced and white crystals of 12 were ob-
tained. 12: 1H-NMR (C6D8, 25°C) l: 1.26 (d, 12H,
ꢀJHꢀHꢀ=7 Hz, CH(CH3)2), 3.30 (sept, 2H, ꢀJHꢀHꢀ=7
Hz, CH(CH3)2), 5.97 (s, 10, Cp), 7.03 (m, 3H, Ar).
13C{1H}-NMR (C6D8, 25°C) l: 24.3 (CH(CH3)2), 30.4
(CH(CH3)2), 113.5 (Cp), 121.0 (Ar), 123.9 (Ar), 136.3
(o-Ar), 160.0 (ipso-Ar). Calc. for C22H27ClOZr; C:
2.5. Generation of CpTiMe2(OC6H3-i-Pr2) (8)
To 1 (100 mg, 0.26 mmol) suspended in hexane was
added MeMgBr (367 ml of a 1.4 M solution in THF,
0.52 mmol). The reaction mixture was stirred
overnight, then filtered, after which the solvent was
evaporated. 1H-NMR (C6D6, 25°C) l: 1.08 (s, 6H,
Tiꢀ(CH3)2), 1.20 (d, 12H, ꢀJHꢀHꢀ=7 Hz, CH(CH3)2),
3.33 (sept, 2H, ꢀJHꢀHꢀ=7 Hz, CH(CH3)2), 5.90 (s, 5H,
Cp), 6.98 (t, 1H, ꢀJHꢀHꢀ=7 Hz, p-Ar), 7.10 (d, 2H,
ꢀJHꢀHꢀ=7 Hz, m-Ar). 13C{1H}-NMR (C6D6, 25°C) l:
23.5 (CH(CH3)2), 26.9 (CH(CH3)2), 54.0 (Tiꢀ(CH3)2),
113.7 (Cp), 122.2 (Ar), 123.2 (Ar), 137.8 (o-Ar), 161.0
(ipso-Ar).
1
60.87; H:6.27; Found: C: 60.64; H: 6.17. 13: H-NMR
(C6D6, 25°C, l): 7.19 (t, 2H, ꢀJHꢀHꢀ=7 Hz, Ar), 6.85
(t, 1H, ꢀJHꢀHꢀ=7 Hz, Ar), 6.68 (d, 2H, ꢀJHꢀHꢀ=7 Hz,
Ar), 5.93 (s, 10H, Cp).
2.6. Reactions of 1, 2, 6, 7 with AlMe3
2.10. Synthesis of Cp2ZrMe(OC6H5) (14)
These reactions were prepared in a similar manner
and thus only one representative preparation is de-
scribed. 2 (25 mg, 0.05 mmol) dissolved in C6D6 was
added AlMe3 (25 ml (2 M in toluene), 0.05 mmol). The
reaction was allowed to stir at 25°C for 12 h and then
monitored by NMR spectroscopy.
To an off-white mixture of 85 mg (0.335 mmol)
Cp2ZrMeCl in benzene was added a bright white sus-
pension of 34 mg (0.340 mmol) LiOC6H5 in benzene.
The mixture was stirred for 15 h and filtered. The
straw-yellow filtrate was evaporated to give an off-
1
white oily solid in 74% yield. H-NMR (C6D6, 25°C,
l): 7.19 (t, 2H, ꢀJHꢀHꢀ=7 Hz, Ar), 6.84 (t, 1H,
ꢀJHꢀHꢀ=7 Hz, Ar), 6.58 (d, 2H, ꢀJHꢀHꢀ=7 Hz, Ar), 5.75
(s, 10H, Cp), 0.46 (s, 3H, Me). 13C{1H}-NMR (C6D6,
25°C, l): 165.4 (ipso-Ar), 129.6 (Ar), 119.5 (Ar), 118.2
(Ar), 111.2 (Cp), 22.4 (Me).
2.7. Synthesis of [AlMe2(OC6H3-i-Pr2)]2 (9)
To AlMe3 (25 ml, (2 M in toluene), 0.5 mmol) in
benzene was added HOC6H3-i-Pr2 (89 mg, 0.5 mmol).
Gas evolution was apparent immediately. The solvent
was then reduced and white crystals of (AlMe2(OR*))2
2.11. Synthesis of Cp2TiCl(OC6H3-i-Pr2) (15)
1
were observed within 7 days. H-NMR (C6D8, 25°C) l:
−0.34 (s, 12H, AlꢀCH3), 1.26 (d, 24H, CH(CH3)2),
3.77 (sept, 4H, ꢀJHꢀHꢀ=7 Hz, CH(CH3)2), 7.03 (br, 6H,
Ar). 13C{1H}-NMR (C6D8, 25°C) l: −0.04 (AlꢀCH3),
25.7 (CH(CH3)2), 26.9 (CH(CH3)2), 125.6 (Ar), 125.8
(Ar), 141.3 (o-Ar), 154.1 (ipso-Ar). HRMS for
C28H46O2Al2: 468.3128, Found: 468.3143. Anal. Calc.;
C: 71.76; H: 9.89; C: 71.66; H: 9.79.
To Cp2TiCl2 (100 mg 0.18 mmol) in benzene was
added HOC6H3-i-Pr2 (32.1 mg, 0.18 mmol) and NEt3
(35 ml, 0.25 mmol). The mixture was allowed to stir for
12 h, then filtered. After the solvent was removed,
an orange solid was obtained in 62% yield. 1H-
NMR (C6D8, 0°C) l: 1.23 (d, 6H, ꢀJHꢀHꢀ=7 Hz,
CH(CH3)2), 1.61 (d, 6H, ꢀJHꢀHꢀ=7 Hz, CH(CH3)2),
2.90 (sept, 2H, ꢀJHꢀHꢀ=7 Hz, CH(CH3)2), 4.82 (sept,
2H, ꢀJHꢀHꢀ=7 Hz, CH(CH3)2) 6.00 (s, 10H, Cp), 7.04–
7.12 (3t, 3H, Ar). 13C{1H}-NMR (C6D8, 25°C) l: 23.0
(CH(CH3)2), 25.3 (CH(CH3)2), 110.3 (Cp), 118.9 (Ar),
122.4 (Ar), 134.6 (o-Ar), 164.1 (ipso-Ar). Calc. for
C22H27ClOTi; C: 67.61; H:6.96; Found: C: 67.49; H:
6.89.
2.8. Synthesis of [CpTi(O2C6H4)·AlClMe2]2 (11)
To 10 (100 mg, 0.39 mmol) dissolved in benzene was
added AlMe3 (196 ml of a 2 M in toluene, 0.39 mmol).
The reaction was allowed to stir at 25°C for 12 h. The
solvent was reduced and bright blue crystals of

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A.V. Firth et al. / Journal of Organometallic Chemistry 591 (1999) 185–193
2.12. X-ray data collection and reduction
nals. The reflections with F2o\3|Fo2 were used in the
refinements.
X-ray-quality crystals of 2, 3, 6, 9, 11–13 were
obtained directly from the preparations described
above. The crystals were manipulated and mounted in
capillaries in a glove box, thus maintaining a dry,
O2-free environment for each crystal. Diffraction exper-
iments were performed on a Rigaku AFC6 diffractome-
ter equipped with graphite-monochromatized Mo–Ka
radiation. The initial orientation matrices were ob-
tained from 20 machine-centered reflections selected by
an automated peak search routine. These data were
used to determine the crystal systems. Automated Laue
system check routines around each axis were consistent
with the crystal system. Ultimately, 25 reflections (20B
2qB25°) were used to obtain the final lattice parame-
ters and the orientation matrices. Crystal data are
summarized in Table 1. The observed extinctions were
consistent with the space groups in each case. The data
sets were collected in three shells (4.5B2qB45–50.0°)
and three standard reflections were recorded every 197
reflections. Fixed scan rates were employed. Up to four
repetitive scans of each reflection at the respective scan
rates were averaged to insure meaningful statistics. The
number of scans of each reflection was determined by
the intensity. The intensities of the standards showed
no statistically significant change over the duration of
the data collections. The data were processed using the
TEXSAN crystal solution package operating on an SGI
Challenge mainframe computer with remote X-termi-
2.13. Structure solution and refinement
Non-hydrogen atomic scattering factors were taken
from the literature tabulations [30,31]. The heavy atom
positions were determined using direct methods em-
ploying either the SHELX-86 or Mithril direct methods
routines. The remaining non-hydrogen atoms were lo-
cated from successive difference Fourier map calcula-
tions. The refinements were carried out by using
full-matrix least squares techniques on F, minimizing
the function ꢀ(ꢀ Fo ꢀ−ꢀ Fc ꢀ)2 where the weight ꢀ is
defined as 4F2o/2|(Fo2) and Fo and Fc are the observed
and calculated structure factor amplitudes. In the final
cycles of each refinement, the number of non-hydrogen
atoms assigned anisotropic temperature factors was
determined so as to maintain a reasonable data:variable
ratio. The remaining atoms were assigned isotropic
temperature factors. In some instances the geometries
of the cyclopentadienyl and phenyl rings were also
constrained to maintain a statistically meaningful
data:variable ratio. Where appropriate, empirical ab-
sorption corrections were applied to the data sets based
on psi-scan data and employing the software resident in
the TEXSAN package. Hydrogen atom positions were
calculated and allowed to ride on the carbon to which
they are bonded assuming a CꢀH bond length of 0.95
,
A. Hydrogen atom temperature factors were fixed at
Table 1
Crystallographic parameters a
2
3
6
9
11
12
13
Formula
Formula weight
C29H39O2TiCl
502.98
10.364(3)
16.245(3)
9.786(3)
100.49(2)
117.93(2)
84.36(2)
1431.2(7)
P-1
1.167
2
0.414
8.0
5364
4.5–50
1627
213
4.50
C33H48O2Ti C30H42O2Ti C28H46O2Al2 C26H30O4Al2Cl2Ti2 C22H27ClOZr
C16H15ClOZr
350.0
14.514(5)
14.217(4)
15.201(9)
524.64
482.56
468.63
621.04
434.0
,
a (A)
17.725(9)
11.039(4)
19.761(8)
12.264(2)
22.128(4)
10.471(2)
17.536(7)
9.606(3)
18.061(3)
16.540(4)
21.237(2)
8.470(2)
10.621(3)
17.994(7)
11.186(3)
,
b (A)
,
c (A)
h (°)
i (°)
k (°)
125.35(3)
93.23(2)
90.38(2)
105.36(3)
3
,
V (A )
3153(2)
Cc
1.105
4
2841.8(9)
Pnma
1.128
4
3037(1)
P21/a
1.025
4
2975(1)
Pbca
1.387
8
2137(1)
P21/n
1.349
4
3024(2)
P21/a
1.537
8
0.892
16
5808
4.5–50.0
825
Space group
Dcalc. (g cm−1
Z
)
v (mm−1
)
0.296
16.0
3055
4.5–50
704
0.318
32.0
2872
4.5–50
732
0.115
16.0
1476
4.5–50
1446
169
0.804
32.0
3000
4.5–45
1099
163
0.637
32.0
4141
4.5–50
1271
116
Scan speed (° min−1
Data collected
2q/index ranges
Data F2o\3|(F2o)
Variables
)
115
81
97
R (%) b
5.90
9.60
2.63
9.80
9.77
2.76
5.40
8.40
2.28
3.33
4.90
1.50
5.90
7.90
2.16
7.50
8.50
1.90
wR (%) b
6.80
1.77
Goodness-of-fit
a All data collected at 24°C with Mo–Ka radiation (u=0.71069 A), a scan range of 1.0 above Ka and 1.0 below Ka , with a background to
,
1
1
scan ratio of 0.5.
2 0.5
b R=SꢀꢀFoꢀ−ꢀFcꢀꢀ/SꢀFoꢀ, wR=[S(ꢀFoꢀ−ꢀFcꢀ)2ꢀ/SꢀFoꢀ ]
.

A.V. Firth et al. / Journal of Organometallic Chemistry 591 (1999) 185–193
189
1.10 times the isotropic temperature factor of the car-
bon atom to which they are bonded. The hydrogen
atom contributions were calculated, but not refined.
Inversion and refinement of the model confirmed where
appropriate the correct enantiomorph of the models.
The final values of R, wR and the goodness of fit in the
final cycles of the refinements are given in Table 1. The
locations of the largest peaks in the final difference
Fourier map calculation as well as the magnitude of the
residual electron densities in each case were of no
chemical significance. CIF tables have been deposited
as supplementary material.
Fig. 1. ORTEP drawing of 2; 30% thermal ellipsoids are shown and
,
hydrogen atoms are omitted for clarity. Ti(1)ꢀCl(1) 2.292(3) A;
,
,
,
Ti(1)ꢀO(1) 1.793(5) A; Ti(1)ꢀO(2) 1.809(6) A; O(1)ꢀC(6) 1.365(9) A;
,
O(2)ꢀC(18) 1.357(9) A; Cl(1)ꢀTi(1)ꢀO(1) 102.2(2)°; Cl(1)ꢀTi(1)ꢀO(2)
103.2(2)°; O(1)ꢀTi(1)ꢀO(2) 103.0(3)°; Ti(1)ꢀO(1)ꢀC(6) 170.3(6)°;
Ti(1)ꢀO(2)ꢀC(18) 149.3(6)°.
2.14. Ethylene polymerization
A solution of 6–10 mmol of catalyst in 2.0 ml of dry
toluene was added to a flask containing 2.0 ml of dry
toluene. 500 equivalents of a 10% by weight toluene
solution of methylaluminoxane (MAO) was added to
the flask. The flask was attached to a Schlenk line with
cold trap, a stopwatch was started and the flask was
three times evacuated for five seconds and refilled with
pre-dried 99.9% ethylene gas. The solution was rapidly
stirred under 1 atmosphere of ethylene at room temper-
ature. The polymerization was stopped by the injection
of a 1.0 M HCl+methanol solution and total reaction
time was noted. The polymer was filtered and washed
with copious amounts of water and placed on a drying
oven for subsequent weighing.
Scheme 1.
3. Results and discussion
The compounds CpTiCl2(OC6H3-i-Pr2)2) (1) was pre-
pared by known methods [24] while CpTiCl(OC6H3-i-
Pr2)2 (2) was obtained by a modification of the known
route. Spectroscopic characterizations of both 1 and 2
were as expected. Crystallographic data confirmed the
formulations and revealed little variation in the TiꢀO
bond distances or in the TiꢀOꢀC angles (Fig. 1). The
two TiꢀO distances for 2 are similar (1.793(5) and
Fig. 2. ORTEP drawing of 3; 30% thermal ellipsoids are shown and
,
hydrogen atoms are omitted for clarity. Ti(1)ꢀO(1) 1.79(2) A;
,
,
,
Ti(1)ꢀO(2) 1.79(2) A; Ti(1)ꢀC(30) 1.97(4) A; Ti(1)ꢀC(31) 2.66(4) A;
,
,
O(1)ꢀC(6) 1.42(2) A; O(2)ꢀC(18) 1.34(2) A; O(1)ꢀTi(1)ꢀO(2)
107.7(9)°; O(1)ꢀTi(1)ꢀC(30) 115(1)°; O(1)ꢀTi(1)ꢀC(31) 94(1)°;
O(2)ꢀTi(1)ꢀC(30) 108(1)°; O(2)ꢀTi(1)ꢀC(31) 89(1)°; Ti(1)ꢀO(1)ꢀC(6)
153(1)°; Ti(1)ꢀO(2)ꢀC(18) 156(1)°; Ti(1)ꢀC(30)ꢀC(31) 96(2)°;
Ti(1)ꢀC(31)ꢀC(30) 47(1)°.
,
1.809(6) A) and yet the TiꢀOꢀC angles differ substan-
tially at 170.3(6) and 149.3(6)°. Although it is tempting
to suggest this difference may result from differing
degrees of p-donation from the phenoxide ligands to
the metal center, one cannot dismiss simple steric
crowding as the cause.
The TiꢀO distance and TiꢀOꢀC angle are similar to
those in 1 and 2. The Ti(1)ꢀC(30) and Ti(1)ꢀC(31)
,
distances of 1.97(4) and 2.66(4) A suggest an agostic
interaction of the Lewis acidic metal center with a CꢀH
bond. Nonetheless, the crystallographic data did not
confirm this as the methyl hydrogen atoms could not be
located. Moreover, no evidence of such an agostic
interaction was evident in the NMR spectral data even
at −80°C.
In analogous reactions of 2 with s-BuLi, n-BuLi and
MeLi, the species CpTi(s-Bu)(OC6H3-i-Pr2)2 4 CpTi(n-
Bu)(OC6H3-i-Pr2)2 5 and CpTi(Me)(OC6H3-i-Pr2)2 6 re-
spectively were obtained. X-ray crystallographic
Alkylation of 2 is achieved via treatment with a
variety of alkyl lithium reagents (Scheme 1). This is in
contrast to the reaction of 1 with BuLi which results in
reduction to what is presumed to be a Ti(III) species.
Treating 2 with t-BuLi yielded the orange crystalline
1
solid 3 in 40% yield. H- and 13C{1H}-NMR spectral
data included resonances at 1.48 and 82.8 ppm. respec-
tively. X-ray crystallographic analysis of 3 confirmed
the formulation as CpTi(t-Bu)(OC6H3-i-Pr2)2 (Fig. 2).

190
A.V. Firth et al. / Journal of Organometallic Chemistry 591 (1999) 185–193
Fig. 3. ORTEP drawing of 6; 30% thermal ellipsoids are shown and
,
hydrogen atoms are omitted for clarity. Ti(1)ꢀO(1) 1.817(9) A;
,
,
Ti(1)ꢀC(16) 2.08(3) A; O(1)ꢀC(1) 1.40(2) A; O(1)ꢀTi(1)ꢀO(1)%
109.0(5)°; O(1)ꢀTi(1)ꢀC(16) 100.5(5)°.
Scheme 2.
analysis of 6 confirmed the formulation (Fig. 3). Inter-
estingly, in this case the two Ti-phenoxide fragments
are identical as this molecule sits on a crystallographic
second aryloxide ligand in the catalyst precursor 2. The
GPC data also indicate significant differences in molec-
ular weight of the resulting polymers. For example,
while Cp2ZrCl2 affords polymer of molecular weight
(Mw) of approximately 100 000, a polymer of Mw
300 000 is obtained from 1. Despite this difference, the
polydispersities of the polymers obtained are essentially
unchanged.
In an effort to model the catalytic system, stoichio-
metric reactions with AlMe3 were examined. Monitor-
ing of the reactions of 1 with 1, 2 and excess equivalents
of AlMe3 revealed the stepwise formation of Cp-
Ti(Me)Cl(OC6H3-i-Pr2) (7) and CpTi(Me)2(OC6H3-i-
Pr2) (8) with the by-product AlMe2Cl (Scheme 2). This
was confirmed by the synthesis of authentic samples of
7 and 8. The analogous reactions of 2 also lead initially
to a mixture of 6, 7 and 8 as confirmed by NMR data.
It appears that the initial reaction of 2 has two viable
pathways, methyl-halide exchange and aryloxide ab-
straction. Addition of a second equivalent of AlMe3
afforded conversion of 6 and 7 to 8.
,
mirror. The TiꢀC distance (2.00(3) A) is within the
experimental error of that seen in 3.
Compounds 1 or 2 in the presence of 500 equivalents
of MAO act as catalyst precursors for ethylene poly-
merization (Table 2). In our experiments, 5–10 mmol of
catalyst precusor were dissolved in 4.0 ml of toluene
and 500 equivalents of MAO were added under an N2
atmosphere. Ethylene was introduced via three succes-
sive pump (5 s)–fill cycles. Following the final fill cycle
the solution was allowed to stir under the ethylene
atmosphere. After 3 min, the catalysis was quenched
via addition of a solution of 1 M aqueous HCl+
methanol. The reaction times were limited to preclude
catalyst entrapment in the polyethylene. The resulting
polyethylene was isolated via filtration, washed with
water, dried to constant weight, and subsequently char-
acterized by GPC. In order to ensure experimental
consistency, catalyst activities were measured in dupli-
cate and standardized against the activity of Cp2ZrCl2
(1 min). These data revealed that the catalysts derived
from the monocyclopentadienyl complexes are much
less active than the metallocenes. As well, these activi-
ties are significantly lower than Nomura et al. [24]
observed under higher pressures of ethylene. Nonethe-
less, the present results show a clear enhancement in the
activity of about 40% as a result of the inclusion of a
The course of aryloxide group transfer was confirmed
via an independent synthesis of the aluminum species
[AlMe2(OC6H3-i-Pr2)]n 9. This was achieved via treat-
ment of AlMe3 with one equivalent of HOC6H3-i-Pr2.
The colorless solid 9 was isolated following the evapo-
ration of the solvent. 1H- and 13C{1H}-NMR spectra of
9 were consistent with the empirical formulation and
Table 2
Polymerization results
Catalyst
Related activity a
Time (min)
Mw (Daltons)
Mw/Mn
CpTiCl2(OC6H3-i-Pr2) (1)
CpTiCl(OC6H3-i-Pr2)2 (2)
CpTi(Me)(OC6H3-i-Pr2)2 (6)
Cp2ZrCl2
Cp2ZrCl(OC6H3-i-Pr2) (12)
Cp2ZrMe(OC6H5) (14)
Cp2TiCl2
0.11
0.16
0.16
1.00
1.11
1.11
0.77
0.85
3
3
3
1
1
1
1
1
336 866
110 000
160 300
116 353
23 200
–
2.65
2.20
2.18
2.84
2.48
–
69 500
40 700
6.88
3.99
Cp2TiCl(OC6H3-i-Pr2) (15)
a Catalyst activities are reported relative to that observed for Cp2ZrCl2 in the presence of 500 equivalents of MAO at 25oC and 1 atm of
ethylene. Under these conditions the activity of Cp2ZrCl2/MAO was 795 g of PE/mmol of catalyst/h.

A.V. Firth et al. / Journal of Organometallic Chemistry 591 (1999) 185–193
191
crystallographic analysis confirmed the dimeric nature
(Fig. 4), in which two aluminum centers are bridged by
two phenoxide oxygen atoms. The AlꢀO and AlꢀC
distances were similar to those seen in the analogous
species [AlMe2(m-OC6H2-2,4,6-t-Bu3)]2 [32]. Compound
9 is the sole aluminum product in the reactions of 2
with AlMe3.
The related catecholate complex CpTi(O2C6H4)Cl 10
was prepared as described in the literature [26]. This
species is a structural relative of 2 although the chelat-
ing nature of the catechol ligand was expected to alter
the reaction pathway with AlMe3. Treatment of 9 with
one equivalent of AlMe3 resulted in a dark solution
over a period of several days. Blue crystals of the
Fig. 5. ORTEP drawing of 11; 30% thermal ellipsoids are shown and
,
hydrogen atoms are omitted for clarity. Ti(1)ꢀCl(1) 2.541(3) A;
Ti(1)ꢀO(1) 2.079(5) A; Ti(1)ꢀO(2) 2.059(4) A; Ti(1)ꢀO(2) 2.063(5) A;
,
,
,
,
,
Cl(1)ꢀAl(1) 2.275(3) A; Al(1)ꢀO(1) 1.842(5) A; Al(1)ꢀC(12) 1.948(9)
A; Al(1)ꢀC(13) 1.934(8) A; O(1)ꢀC(1) 1.387(7) A; O(2)ꢀC(2) 1.371(7)
,
,
,
,
A;
Cl(1)ꢀTi(1)ꢀO(1)
75.2(2)°;
Cl(1)ꢀTi(1)ꢀO(2)
128.1(1)°;
Cl(1)ꢀTi(1)ꢀO(2) 89.4(2)°; O(1)ꢀTi(1)ꢀO(2) 76.1(2)°; O(1)ꢀTi(1)ꢀO(2)
127.4(2)°; O(2)ꢀTi(1)ꢀO(2) 75.2(2)°; Ti(1)ꢀCl(1)ꢀAl(1) 85.3(1)°;
Cl(1)ꢀAl(1)ꢀO(1) 86.7(2)°; Cl(1)ꢀAl(1)ꢀC(12) 109.5(3)°; Cl(1)ꢀ
Al(1)ꢀC(13) 110.3(3)°; O(1)ꢀAl(1)ꢀC(12) 110.0(3)°; O(1)ꢀAl(1)ꢀC(13)
111.2(4)°; C(12)ꢀAl(1)ꢀC(13) 123.2(4)°; Ti(1)ꢀO(1)ꢀAl(1) 112.8(3)°;
Ti(1)ꢀO(1)ꢀC(1) 113.2(4)°; Al(1)ꢀO(1)ꢀC(1) 128.2(5)°; Ti(1)ꢀO(2)ꢀ
Ti(1) 104.8(2)°; Ti(1)ꢀO(2)ꢀC(2) 115.2(4)°; Ti(1)ꢀO(2)ꢀC(2) 133.7(4)°.
paramagnetic complex 11 (g=1.197) were isolated in
73% yield. This species was subsequently characterized
as [CpTi(O2(C6H4))·AlClMe2]2 11 by crystallographic
methods (Scheme 3, Fig. 5). Complex 11 is a bimetallic
bridged species in which one of the oxygen atoms of
each catecholate ligands bridge the two Ti(III) centers
forming a Ti2O2 core. The average TiꢀO distances
,
within this core is 2.069(5) A. The second oxygen atom
of the catecholates, as well as a chloride atom, bridge
the titanium and aluminum centers. These TiꢀO dis-
Fig. 4. ORTEP drawing of 9; 30% thermal ellipsoids are shown and
,
tances of 2.063(5) A are indistinguishable from those in
,
hydrogen atoms are omitted for clarity. Al(1)ꢀO(1) 1.862(7) A;
Al(1)ꢀO(2) 1.852(7) A; Al(1)ꢀC(25) 1.93(1) A; Al(1)ꢀC(26) 1.95(1) A;
,
the core. The TiꢀCl distance of 2.541(2) A is quite long
,
,
,
,
,
,
Al(2)ꢀO(1) 1.861(7) A; Al(2)ꢀO(2) 1.877(7) A; Al(2)ꢀC(27) 1.93(1) A;
,
compared to those of CpTiCl3, (2.25 A), consistent with
,
,
,
Al(2)ꢀC(28) 1.95(1) A; O(1)ꢀC(1) 1.40(1) A; O(2)ꢀC(13) 1.43(1) A;
O(1)ꢀAl(1)ꢀO(2) 80.2(3)°; O(1)ꢀAl(1)ꢀC(25) 115.4(5)°; O(1)ꢀAl(1)
ꢀC(26) 113.8(5)°; O(2)ꢀAl(1)ꢀC(25) 117.5(5)°; O(2)ꢀAl(1)ꢀC(26)
111.4(4)°; C(25)ꢀAl(1)ꢀC(26) 114.3(6)°; O(1)ꢀAl(2)ꢀO(2) 79.6(3)°;
O(1)ꢀAl(2)ꢀC(27) 113.0(4)°; O(1)ꢀAl(2)ꢀC(28) 115.8(4)°; O(2)ꢀAl(2)ꢀ
C(27) 113.7(4)°; O(2)ꢀAl(2)ꢀC(28) 115.1(5)°; C(27)ꢀAl(2)ꢀC(28)
114.9(5)°; Al(1)ꢀO(1)ꢀAl(2) 99.8(4)°; Al(1)ꢀO(1)ꢀC(1) 130.0(6)°;
Al(2)ꢀO(1)ꢀC(1) 130.2(6)°; Al(1)ꢀO(2)ꢀAl(2) 99.6(4)°; Al(1)ꢀO(2)ꢀ
C(13) 132.7(6)°; Al(2)ꢀO(2)ꢀC(13) 127.7(6)°.
an AlCl2Me adduct of the Ti(III) centers. The relative
disposition of the cyclopentadienyl ligands in the Ti2Al2
species is transoid. The mechanism by which 10 is
reduced is unknown. Speculation suggests a process in
which association of 10 with AlMe3 is followed by a
bimetallic reductive elimination of ethane.
The above observations create a picture in which
initial association of aluminum reagents with aryloxide
ligands promotes ligand abstraction. This, of course, is
subverted by the chelate effect in the case of 10. For the
aryloxide complexes this process occurs for both stoi-
chiometric and catalytic reaction conditions. The in-
crease in catalytic activity of 2 over 1 prompts the
question as to whether such ligand incorporation will
have the same effect in catalysts where the activity is in
a higher regime. This prompted us to prepare modified
metallocenes. An alternative synthesis of the known
species Cp2ZrCl(OC6H3-i-Pr2) 12 [25] was derived from
Scheme 3.

192
A.V. Firth et al. / Journal of Organometallic Chemistry 591 (1999) 185–193
treating Cp2ZrHCl with HOC6H3-i-Pr2 (Scheme 4).
Subsequent solvent removal afforded colorless crystals
of 12. NMR data were consistent with the formulation
of 12 as Cp2ZrCl(OC6H3-i-Pr2). X-ray crystallography
confirmed this formulation (Fig. 6). The ZrꢀO of
,
1.97(1) A and the ZrꢀOꢀC angle of 172(1)° are typical,
suggesting some p-interaction between Zr and O. The
analogous compounds Cp2ZrCl(OC6H5) 13 was pre-
pared in an similar manner. X-ray data for 13 (Fig. 7)
,
revealed that the ZrꢀO distance in 13 (1.99(3) A) was
similar to that seen in 12 despite the fact that the
ZrOꢀC angle is diminished to 150(2)°.
While 13 was prepared and characterized, attempts
to prepare this compound for catalysis testing were
hindered by difficulties in the separation from small
amounts of Cp2Zr(OC6H5)2 and Cp2ZrCl2. In contrast,
the species Cp2ZrMe(OC6H5) 14 was readily and
cleanly prepared from Cp2ZrMeCl and LiOPh. In addi-
tion, the titanium complex Cp2TiCl(OC6H3-i-Pr2) (15)
was prepared from Cp2TiCl2 with HOC6H3-i-Pr2 and
base (Scheme 4). The 1H-NMR spectra of 15 at reduced
temperatures show two resonances attributable to the
cyclopentadienyl groups as well as two AX6 patterns
attributable to the protons of the isopropyl groups.
These observations suggest a bent geometry at oxygen
and restricted rotation about the TiꢀO bond at lower
temperatures.
Scheme 4.
Ethylene polymerizations were performed employing
12, 14 and 15 with MAO as described above. The
results confirm an 11% increase in activity for these
aryloxide derivatives compared to the parent metal-
locenedichlorides. In addition, Repo et al. [25] have
recently shown that the activity of Cp2ZrCl(OC6H3-t-
Bu2) is strongly dependent on the reaction condition.
Comparing activities at 30°C and 2 bar ethylene to that
at 80°C and 10 bar ethylene, an increase of 30% in
activity was observed.
Fig. 6. ORTEP drawing of 12; 30% thermal ellipsoids are shown and
,
hydrogen atoms are omitted for clarity. Zr(1)ꢀCl(1) 2.468(4) A;
Zr(1)ꢀO(1) 1.97(1) A; O(1)ꢀC(11) 1.33(2)°; Cl(1)ꢀZr(1)ꢀO(1) 99.6(3)°;
,
Zr(1)ꢀO(1)ꢀC(11) 172(1)°.
In model reactions of 12 with one equivalent of
AlMe3, 1H-NMR data confirm that 12 is converted
quantitatively to Cp2ZrMe(OC6H3-i-Pr2) while addition
of a further equivalent of AlMe3 results in the clean
conversion to the known complex Cp2ZrMe2. The alu-
minum byproduct 9 was also observed by NMR spec-
troscopy. These model reactions again suggest that
alkylation and aryloxide abstraction in the catalytic
system generate similar Zr centers.
The increased activity for the aryloxide derivatives
suggests that generation of active sites via aryloxide
abstraction is more efficient than alkyl abstraction.
Alternatively, it may be that transfer of the bulky
aryloxide to aluminum enhances charge separation of
the active metal-based cationic center from the corre-
sponding counter-anion. It is also interesting to note
that while activity is increased, the Mw of the resulting
polyethylene is decreased significantly. Although the
increased activity may reflect the leaving ability of
aryloxide versus halide, the decrease in Mw suggests
that aryloxide ligation promotes chain transfer to alu-
minum and thus premature termination of the polymer.
Fig. 7. ORTEP drawing of 13; 30% thermal ellipsoids are shown and
,
hydrogen atoms are omitted for clarity. Zr(1)ꢀCl(1) 2.47(1) A;
,
,
,
Zr(1)ꢀO(1) 1.98(3) A; Zr(2)ꢀCl(2) 2.45(1) A; Zr(2)ꢀO(2) 2.01(3) A;
Cl(1)ꢀZr(1)ꢀO(1) 95.6(9)°; Cl(2)ꢀZr(2)ꢀO(2) 97.8(8)°; Zr(1)ꢀO(1)ꢀ
C(11) 149(1)°; Zr(2)ꢀO(2)ꢀC(27) 150(2)°.

A.V. Firth et al. / Journal of Organometallic Chemistry 591 (1999) 185–193
193
[9] M.K. Leclerc, H.H. Brintzinger, J. Am. Chem. Soc. 118 (1996)
9024.
4. Supplementary information
[10] G.C. Bazan, S.J. Donnelly, G. Ridriguez, J. Am. Chem. Soc. 117
(1995) 2671.
Crystallographic data in CIF format have been de-
posited with the Cambridge Crystallographic database.
(CCDC nos. 121660 to CCDC 121666, inclusive).
Copies of this information may be obtained free of
charge from: The Director, CCDC, 12 Union Road,
Cambridge, CB2 1EZ, UK (Fax: +44-1223-336-033;
email: deposit@ccdc.cam.ac.uk or www: http://www.
ccdc.cam.ac.uk).
[11] G.C. Bazan, G. Ridriguez, J. Am. Chem. Soc. 118 (1996) 2291.
[12] G. Rodriguez, G.C. Bazan, J. Am. Chem. Soc. 119 (1997) 343.
[13] G.C. Bazan, G. Rodriguez, Organometallics 16 (1997) 2492.
[14] T.K. Woo, P.M. Margl, J.C.W. Lohrenz, P.E. Blochl, T. Ziegler,
J. Am. Chem. Soc. 118 (1996) 13021.
[15] X.Y. Chen, C.L.Y. Stern, T.J. Marks, J. Am. Chem. Soc. 118
(1996) 12451.
[16] Y. Sun, R.E.V.H. Spence, W.E. Piers, M. Parvez, G.P.A. Yap, J.
Am. Chem. Soc. 119 (1997) 5132.
[17] S. Fokken, T.P. Spaniol, H.-C. Kang, W. Massa, J. Okunda,
Organometallics 15 (1995) 5069.
[18] D.P. Long, P.A. Bianconi, J. Am.Chem. Soc. 118 (1996) 12453.
[19] T. Tsukahara, D.C. Swenson, R.F. Jordan, Organometallics 16
(1997) 3303.
Acknowledgements
Financial support from the NSERC of Canada is
gratefully acknowledged. Bayer Rubber Inc., Sarnia
and Nova Chemicals, Calgary are thanked for supply-
ing GPC data.
[20] T.L. Tremblay, S.W. Ewart, M.J. Sarsfield, M.C. Baird, Chem.
Commun. (Cambridge) (1997) 831.
[21] A.V. Firth, D.W. Stephan, Organometallics 16 (1997) 2183.
[22] A.V. Firth, D.W. Stephan, Inorg. Chem. 37 (1998) 4726.
[23] A.V. Firth, D.W. Stephan, Inorg. Chem. 37 (1998) 4732.
[24] K. Nomura, N. Naga, M. Miki, K. Yanagi, A. Imai,
Organometallics 17 (1998) 2152.
References
[25] T. Repo, G. Jany, M. Salo, M. Polamo, M. Leskela, J.
Organomet. Chem. 541 (1997) 363.
[1] M. Bochmann, J. Chem. Soc. Dalton Trans. (1996) 255.
[2] Y.-X. Chen, C.L. Stern, T.J. Marks, J. Am. Chem. Soc. 119
(1997) 2582.
[3] P.A. Deck, T.J. Marks, J. Am. Chem. Soc. 117 (1995) 6128.
[4] P.A. Deck, C.L. Beswick, T.J. Marks, J. Am. Chem. Soc. 120
(1998) 1772.
[5] J.P. Mitchell, S. Hajela, S.K. Brookhart, K.I. Hardcastle, L.M.
Henling, J.E. Bercaw, J. Am. Chem. Soc. 118 (1996) 1045.
[6] J.H. Gilchrist, J.E. Bercaw, J. Am. Chem. Soc. 118 (1996) 12021.
[7] C. Fritze, M.K. Knickmeier, G. Erker, F. Zaegel, B. Gautheron,
P. Meunier, L.A. Paquette, Organometallics 14 (1995) 5446.
[8] M. Knickmeier, G. Erker, T. Fox, J. Am. Chem. Soc. 118 (1996)
40.
[26] J.R. Strauss, J. Chem. Soc. Chem. Commun. (1965) 567.
[27] G.J. Erskine, G.J.B. Hurst, E.L. Weinberg, B.K. Hunter, J.D.
McCowan, J. Organomet. Chem. 267 (1984) 265.
[28] I.M.M. Fussing, D. Pletcher, R. Whitby, J. Organomet. Chem.
470 (1994) 109.
[29] D.M. Healy, J.W. Ziller, A. Barron, J. Am. Chem. Soc. 112
(1990) 2949.
[30] D.T. Cromer, J.B. Mann, Acta Crystallogr. Sect. A Crystallogr.
Phys. Theor. Gen. Crystallogr. A 24 (1968) 324.
[31] D.T. Cromer, J.B. Mann, Acta Crystallogr. Sect. A Crystallogr.
Phys. Theor. Gen. Crystallogr. A 24 (1968) 390.
[32] B. Cetinkaya, P.B. Hitchcock, H.A. Jasim, M.F. Lappert, H.D.
Williams, Polyhedron 9 (1990) 239.
.