Titanium pyridyl-phosphinimide complexes - Synthesis, structure, and ethylene polymerization catalysis

Article abstract of DOI:10.1139/V06-071

A series of Ti-pyridyl-phosphinimide complexes of the form Cp′TiX₂[NPR₂(2-CH₂Py)] (Cp′ = Cp, Cp*, R = i-Pr, t-Bu, X = Cl, Me) have been prepared and characterized. These complexes generate ethylene polymerization catalysts upon activation with MAO or B(C₆F₅)₃. The resulting polymers exhibit broad molecular weight distributions. The role of the pyridyl group is discussed in light of stoichiometric reactions of CpTiCl₂[NPR ₂(2-CH₂Py)] with B(C₆F₅) ₃.

Full text of DOI:10.1139/V06-071

755
Titanium pyridyl-phosphinimide complexes —
Synthesis, structure, and ethylene polymerization
catalysis
Chad Beddie, Pingrong Wei, and Douglas W. Stephan
Abstract: A series of Ti–pyridyl-phosphinimide complexes of the form Cp′TiX2[NPR2(2-CH2Py)] (Cp′ = Cp, Cp*, R =
i-Pr, t-Bu, X = Cl, Me) have been prepared and characterized. These complexes generate ethylene polymerization cata-
lysts upon activation with MAO or B(C6F5)3. The resulting polymers exhibit broad molecular weight distributions. The
role of the pyridyl group is discussed in light of stoichiometric reactions of CpTiCl2[NPR2(2-CH2Py)] with B(C6F5)3.
Key words: phosphinimide complexes, pyridyl-phosphinimides, olefin polymerization.
Résumé : On a préparé et caractérisé une série de complexes Ti–pyridyl-phosphinimide de la forme Cp′TiX2[NPR2(2-
CH2Py)] (Cp′ = Cp, Cp*, R = i-Pr, t-Bu, X = Cl, Me). Par activation avec du MAO ou du B(C6F5)3, ces complexes
peuvent générer des catalyseurs pour la polymérisation de l’éthylène. Les polymères ainsi obtenus présentent de larges
distributions de poids moléculaires. On discute du rôle du groupe pyridyle à la lumière des réactions stoechiométriques
du CpTiCl2[NPR2(2-CH2Py)] avec le B(C6F5)3.
Mots clés : complexe du phosphimide, pyridyl-phosphimides, polymérisation d’oléfines.
[Traduit par la Rédaction] Beddie et al. 761
Introduction
precursors that offer the possibility of generating several
single-site catalysts upon activation. To this end, we report
the synthesis and evaluation of Ti–phosphinimide complexes
that incorporate pendant pyridyl substituents. The notion
here is that these substituents may interact with the Lewis
acid activators in a reversible manner and thus afford the
possibility of two or more catalysts in solution. In this, our
first report employing this strategy, we describe the synthe-
sis and characterization of such compounds and evaluate
such species in ethylene polymerization catalysis. The effect
of the pyridyl group on the polymer molecular weight distri-
butions is considered and discussed.
The quest for new and effective homogeneous olefin poly-
merization catalysts have prompted much interest in early
transition metal chemistry over the last two decades. Studies
of non-metallocene systems have probed a wide variety of
novel ancillary ligands (1–3). In our own work we have de-
scribed titanium catalysts that contain bulky-phosphinimide
ligands. This family of compounds of the form
CpTi(NPR3)Cl2 yield active ethylene polymerization cata-
lysts upon activation by MAO (4–10), while activation of the
species Ti(t-Bu3PN)2Me2 by B(C6F5)3 or Ph3C[B(C6F5)4]
provides a remarkably active catalyst, producing polyethyl-
ene of narrow polydispersity and relatively high molecular
weight (7). Single-site or living polymerization catalysts typ-
ically afford narrow polydispersities (1.0–2.0), however, in
practical terms such resins prove difficult to process (11,
12). Thus, while single-site polymerization offers access to
unique polymers, such materials prompt other problems. A
number of methods can be employed to alter both the molec-
ular weight and the molecular weight distributions of result-
ing polymers. In some cases, controlled hydrogenolysis (13,
14) can be utilitzed to broaden the molecular weight distri-
butions. Alternatively, sequential catalysts can be employed
to produce bimodal resins (15–29). In attempting to address
this issue, we are examining potential single-site catalyst
Experimental
General data
All preparations were done under an atmosphere of dry,
O2-free N2 employing both Schlenk line techniques and a
MBraun inert atmosphere glovebox. Solvents were purified
employing a Grubbs’ type solvent purification system manu-
factured by Innovative Technology. All organic reagents
1
were purified by conventional methods. H, 31P{1H}, and
13C{1H} NMR spectra were recorded on Bruker Avance-300
and -500 spectrometers. All spectra were recorded in C6D6
at 25 °C unless otherwise noted. All chemical shifts are re-
ported in ppm. Trace amounts of protonated solvents were
used as references and chemical shifts are reported relative
to SiMe4. 31P{1H} NMR spectra were referenced to external
85% H3PO4. Combustion analyses were done in-house em-
ploying a PerkinElmer CHN analyzer. The compounds
PR2(2-CH2Py) (R = i-Pr (1), t-Bu (2)) (30, 31), and
Me3SiNP(i-Pr)2(2-CH2Py) (3) (32)) were prepared by litera-
ture methods. CpTiCl3, Cp*TiCl3 (Cp* = Me5Cp), and
Received 16 January 2006. Published on the NRC Research
Press Web site at http://canjchem.nrc.ca on 12 May 2006.
C. Beddie, P. Wei, and D.W. Stephan.1 Department of
Chemistry and Biochemistry, University of Windsor, Windsor,
ON N9B 3P4, Canada.
1Corresponding author (e-mail: stephan@uwindsor.ca).
Can. J. Chem. 84: 755–761 (2006)
doi:10.1139/V06-071
© 2006 NRC Canada

756
Can. J. Chem. Vol. 84, 2006
3
3
Me3SiN3 were purchased from Strem Chemical Co. and
Sigma-Aldrich Chemical Co., respectively, and employed
without further purification. MAO and Al(i-Bu)3, as well as
GPC analysis service, were generously provided by NOVA
Chemicals Corp.
3JH-H = 7 Hz, Me), 0.94 (dd, 6H, JP-H = 16 Hz, JH-H
=
7 Hz, Me). 13C{1H} NMR δ: 154.2 (d, JP-C = 7 Hz, Py,
(ipso-C)), 149.7 (s, Py), 135.8 (s, Py), 126.3 (s, Cp*), 126.2
2
1
(s, Py), 122.1 (s, Py), 35.1 (d, JP-C = 51 Hz, CH2), 27.6 (d,
1JP-C = 59 Hz, CH), 16.6 (d, JP-C = 2 Hz, Me), 16.3 (d, δ:
2
2JP-C = 2 Hz, Me), 13.5 (s, Cp*). Elemental anal. calcd.:
C 55.36, H 7.39, N 5.87; found: C 55.13, H 7.49, N 5.58.
31P{1H} NMR δ: 30.6 (s). X-ray quality crystals were ob-
tained via slow evaporation of a toluene solution. 8: Yield:
Synthesis of Me3SiNP-t-Bu2(2-CH2Py) (4)
To a solution of 2 (1.99 g, 8.38 mmol) in toluene (30 mL)
was added Me3SiN3 (2.24 mL, 16.9 mmol). The resulting
solution was heated at refluxing temperature for 48 h. The
volume of the solution was reduced to ca. 5 mL, and the so-
lution was filtered through Celite. The remaining solvent and
excess Me3SiN3 were removed under vacuum, resulting in a
1
3
0.561 g, 1.11 mmol, 72%. H NMR δ: 8.28 (d, 1H, JH-H
4 Hz, Py), 7.61 (d, 1H, JH-H = 6 Hz, Py), 7.16 (m, 1H, Py),
=
3
3
3
6.59 (dd, 1H, JH-H = 6 Hz, JH-H = 6 Hz, Py), 3.59 (d, 2H,
2JP-H = 14 Hz, CH2), 2.19 (s, 15H, Cp*), 1.17 (d, 18H,
3JP-H = 15 Hz, t-Bu). 13C{1H} NMR δ: 154.9 (d, JP-C
=
2
1
pale yellow oil. Yield: 2.06 g, 6.36 mmol, 76%. H NMR δ:
7 Hz, Py, (ipso-C)), 149.4 (s, Py), 136.7 (s, Py), 127.1 (d,
3JP-C = 4 Hz, Py), 126.2 (s, Cp*), 122.3 (s, Py), 39.5 (d,
1JP-C = 52 Hz, t-Bu), 35.7 (d, 1JP-C = 45 Hz, CH2), 28.1 (s, t-
Bu), 13.5 (s, Cp*). 31P{1H} NMR δ: 38.0 (s). Elemental
anal. calcd.: C 56.23, H 7.59, N 5.70; found: C 56.52,
H 7.75, N 5.65. X-ray quality crystals were obtained via
slow evaporation of a toluene solution.
3
8.41 (d, 1H, JH-H = 4 Hz, Py), 7.44 (m, 1H, Py), 7.17 (m,
1H, Py), 6.65 (m, 1H, Py), 3.14 (d, 2H, 2JP-H = 11 Hz, CH2),
3
1.04 (d, 18H, JP-H = 14 Hz, t-Bu), 0.30 (s, 9H, SiMe3).
13C{1H} NMR δ: 157.0 (d, 2JP-C = 7 Hz, Py, (ipso-C)), 149.4
(s, Py), 135.3 (s, Py), 126.1 (s, Py), 121.6 (s, Py), 37.5 (d,
1JP-C = 61 Hz, t-Bu), 34.8 (d, 1JP-C = 53 Hz, CH2), 27.8 (s, t-
Bu), 5.3 (s, SiMe3). 31P{1H} NMR δ: 25.9 (s).
Syntheses of CpTiCl2[NPR2(2-CH2Py)]·B(C6F5)3 (R = i-
Pr (9), t-Bu (10))
Syntheses of Cp′TiCl2[NPR2(2-CH2Py)] (Cp′ = Cp, i-Pr
(5), t-Bu (6), Cp′ = Cp*, R = i-Pr (7), t-Bu (8))
These complexes were prepared in similar fashions and
thus only one preparation is detailed. To a yellow slurry of
CpTiCl3 (0.370 g, 1.69 mmol) in toluene (40 mL) was added
a solution of 3 (0.501 g, 1.69 mmol) in toluene (10 mL). The
resulting solution was stirred for 12 h at room temperature.
The solvent and volatile products were removed under vac-
uum to cause the formation of a yellow crystalline solid,
which was washed with hexanes and dried under vacuum.
These complexes were prepared in similar fashions and
thus only one preparation is detailed. To a yellow solution of
CpTiCl2[NP(i-Pr)2(2-CH2Py)] (5) (0.020 g, 0.49 mmol) in
benzene (2 mL) was added a solution of B(C6F5)3 (0.025 g,
0.049 mmol) in benzene (2 mL). The resulting clear yellow
solution was stirred for 5 min. The solvent was removed un-
der vacuum to produce a yellow solid. Yield: 0.044 g,
0.48 mmol, 98%. 9: H NMR δ: 9.46 (d, 1H, JH-H = 8 Hz,
Py), 8.35 (m, 1H, Py), 7.53 (m, 1H, Py), 6.35 (m, 1H, Py),
6.24 (s, 5H, Cp), 3.43 (dd, 1H, 2JP-H = 12 Hz, 3JH-H = 16 Hz,
1
3
1
Yield: 0.641 g, 1.57 mmol, 93%. 5: H NMR δ: 8.25 (br,
1H, Py), 7.40 (m, 1H, Py), 7.15 (m, 1H, Py), 6.58 (m, 1H,
Py), 6.34 (s, 5H, Cp), 2.97 (d, 2H, 2JP-H = 13 Hz, CH2), 1.68
(d(sept), 2H, 3JP-H = 10 Hz, 3JH-H = 7 Hz, CH), 0.94 (dd, 6H,
2
3
CH2), 3.13 (dd, 1H, JP-H = 12 Hz, JH-H = 16 Hz, CH2),
1.69 (d(sept), 1H, JP-H = 9 Hz, 3JH-H = 7 Hz, CH), 0.94 (m,
1H, CH), 0.76 (dd, 3H, JP-H = 17 Hz, JH-H = 7 Hz, Me),
0.74 (dd, 3H, JP-H = 17 Hz, JH-H = 7 Hz, Me), 0.69 (dd,
2
3
3
3
3
3JP-H = 16 Hz, JH-H = 7 Hz, Me) 0.86 (dd, 6H, JP-H
=
17 Hz, JH-H = 7 Hz, Me). 13C{1H} NMR δ: 153.1 (d,
3
3
3
2JP-C = 7 Hz, Py (ipso-C)), 149.7 (s, Py), 135.6 (s, Py), 126.6
3H, JP-3H = 17 Hz, JH-H = 7 Hz, Me), 0.29 (dd, 3H, JP-H
=
3
3
3
1
(s, Py), 122.6 (s, Py), 115.5 (s, Cp), 33.8 (d, JP-C = 51 Hz,
17 Hz, JH-H = 7 Hz, Me). 13C{1H} NMR (partial, some res-
onances in the C6F5 rings could not be observed) δ: 153.4 (s,
1
2
CH2), 27.3 (d, JP-C = 59 Hz, CH), 16.1 (d, JP-C = 6 Hz,
Me). 31P{1H} NMR δ: 31.7 (s). Elemental anal. calcd.:
C 50.15, H 6.19, N 6.88; found: C 49.95, H 6.41, N 6.76. X-
ray quality crystals were obtained via slow evaporation of a
1
Py (ipso-C)), 148.9 (s, Py), 148.2 (br d, JC-F ~ 240 Hz,
1
C6F5), 143.8 (s, Py), 138.1 (br d, JC-F ~ 230 Hz, C6F5),
131.6 (s, Py), 124.2 (s, Py), 116.3 (s, Cp), 28.3 (d, JP-C
51 Hz, CH2), 28.2 (d, JP-C = 60 Hz, CH), 28.1 (d, JP-C
1
=
=
1
1
1
toluene solution. 6: Yield: 0.320 g, 0.735 mmol, 75%. H
3
3
2
NMR δ: 8.32 (d, 1H, JH-H = 5 Hz, Py), 7.65 (d, 1H, JH-H
=
59 Hz, CH), 16.2 (s, Me), 15.8 (d, JP-C = 3 Hz, Me), 15.3
3
2
8 Hz, Py), 7.26 (m, 1H, Py), 6.63 (dd, 1H, JH-H = 6 Hz,
(s, Me), 15.2 (d, JP-C = 3 Hz, Me). 11B{1H} NMR δ: –3.4
3JH-H = 6 Hz, Py), 6.26 (s, 5H, Cp), 3.06 (d, 2H, JP-H
=
(s). 19F NMR δ: –126.4 (dd, 1F, JF-F = 25 Hz, JF-F
=
2
3
3
11 Hz, CH2), 1.07 (d, 18H, JP-H = 15 Hz, t-Bu). 13C{1H}
25 Hz), –127.0 (br, 1F), –130.4 (d, 1F, JF-F = 23 Hz),
3
3
2
3
3
NMR δ: 153.7 (d, JP-C = 8 Hz, Py, (ipso-C)), 149.6 (s, Py),
136.7 (s, Py), 127.7 (d, JP-C = 3 Hz, Py), 122.6 (s, Py),
–132.6 (br, 2F), –135.2 (dd, 1F, JF-F = 25 Hz, JF-F =
3
25 Hz), –153.7 (dd, 1F, 3JF-F = 21 Hz, 3JF-F = 21 Hz), –154.1
1
1
115.7 (s, Cp), 39.5 (d, JP-C = 51 Hz, t-Bu), 33.0 (d, JP-C
=
(dd, 1F, 3JF-F = 21 Hz, 3JF-F = 21 Hz), –155.8 (dd, 1F, 3JF-F
=
46 Hz, CH2), 27.4 (s, t-Bu). 31P{1H} NMR δ: 36.6 (s). Ele-
mental anal. calcd.: C 52.44, H 6.72, N 6.44; found: C
52.34, H 6.69, N 6.33. X-ray quality crystals were obtained
via slow evaporation of a toluene solution. 7: Yield: 0.748 g,
1.57 mmol, 92%. 1H NMR δ: 8.24 (d, 1H, 3JH-H = 4 Hz, Py),
21 Hz, JF-F = 21 Hz), –160.8 (m, 1F), –162.0 (m, 1F),
–162.1 (m, 1F), –162.6 (m, 1F), –163.3 (m, 1F), –164.0 (m,
1F). 31P{1H} NMR δ: 30.2 (s). Elemental anal. calcd.:
C 45.74, H 2.74, N 3.05; found: C 45.33, H 3.04, N 2.93.
10: Yield: 0.037 g, 0.39 mmol, 85%. H NMR δ: 9.63 (d,
1H, JH-H = 8 Hz, Py), 8.42 (m, 1H, Py), 7.52 (m, 1H, Py),
3
1
3
3
7.18 (d, 1H, JH-H = 6 Hz, Py), 7.06 (m, 1H, Py), 6.55 (dd,
1H, JH-H = 6 Hz, JH-H = 6 Hz, Py), 3.39 (d, 2H, JP-H
15 Hz, CH2), 2.18 (s, 15H, Cp*), 1.93 (d(sept), 2H, JP-H
10 Hz, JH-H = 7 Hz, CH), 1.07 (dd, 6H, JP-H = 16 Hz,
3
3
2
2
=
=
6.37 (m, 1H, Py), 6.30 (s, 5H, Cp), 3.59 (dd, 1H, JP-H
=
3
3
2
13 Hz, JH-H = 18 Hz, CH2), 2.88 (dd, 1H, JP-H = 9 Hz,
3
3
3
3JH-H = 18 Hz, CH2), 0.85 (d, 9H, JP-H = 15 Hz, t-Bu), 0.68
© 2006 NRC Canada

Beddie et al.
757
3
(d, 9H, JP-H = 16 Hz, t-Bu). 13C{1H} NMR (partial): 153.8
8 mL of toluene was injected. In the case of 11, 1, 2, and
10 equiv. of B(C6F5)3 were used as the cocatalyst, while
20 equiv. of Al(i-Bu)3 was used as a scavenger. Catalyst
concentrations of 20 µmol/L were employed, thus
0.012 mmol of catalyst in 4 mL of toluene was injected.
These polymerization experiments were conducted for 10 min.
(s, Py, (ipso-C)), 149.4 (s, Py), 143.6 (s, Py), 137.8 (br d,
1JC-F ~ 260 Hz, C6F5), 131.8 (s, Py), 124.1 (s, Py), 116.5 (s,
1
1
Cp), 40.3 (d, JP-C = 53 Hz, C(CH3)3), 39.6 (d, JP-C
=
=
1
53 Hz, t-Bu), 26.9 (s, t-Bu), 26.6 (s, t-Bu), 26.1 (d, JP-C
41 Hz, CH2). 11B{1H} NMR δ: –3.4 (s). 19F NMR δ: –125.8
3
3
(dd, 1F, JF-F = 25 Hz, JF-F = 25 Hz), –126.6 (br, 1F),
3
–130.9 (d, 1F, JF-F = 25 Hz), –131.7 (br, 1F), –132.8 (m,
1F), −135.5 (m, 1F), –153.6 (dd, 1F, JF-F = 20 Hz, JF-F
X-ray data collection and reduction
3
3
=
Crystals were manipulated and mounted in capillaries in a
glovebox, thus maintaining a dry, O2-free environment for
each crystal. Diffraction experiments were performed on a
Siemens SMART System CCD diffractometer. The data
were collected in a hemisphere of data in 1329 frames with
10 s exposure times. The observed extinctions were consis-
tent with the space groups in each case. The data sets were
collected (4.5° < 2θ < 45–50.0°). A measure of decay was
obtained by recollecting the first 50 frames of each data set.
The intensities of reflections within these frames showed no
statistically significant change over the duration of the data
collections. The data were processed using the SAINT and
XPREP processing packages. An empirical absorption cor-
rection based on redundant data was applied to each data set.
Subsequent solution and refinement was performed using the
SHELXTL solution package operating on a Pentium com-
puter.
3
3
20 Hz), −154.6 (dd, 1F, JF-F = 20 Hz, JF-F = 20 Hz), –155.8
(dd, 1F, 3JF-F = 20 Hz, 3JF-F = 20 Hz), –160.8 (m, 1F), −160.8
(m, 1F), –161.7 (m, 1F), –162.4 (m, 2F), –162.8 (m, 1F),
−163.6 (m, 1F). 31P{1H} NMR δ: 36.3 (s). Elemental anal.
calcd.: C 46.92, H 3.09, N 2.96; found: C 47.33, H 2.94,
N 2.70.
Synthesis of Cp*TiMe2[NP-t-Bu2(2-CH2Py)] (11)
To a yellow suspension of 8 (0.306 g, 0.605 mmol) in a
mixture of diethyl ether (30 mL) and toluene (50 mL) cooled
to –78 °C was added 3.0 mol/L MeMgCl in THF (0.38 mL,
1.14 mmol). The resulting yellow suspension was stirred at
–78 °C for ~20 min and then was slowly warmed to room
temperature over a period of 1.5 h. The solvent was removed
under vacuum, and the crude residue was extracted with
hexanes. The suspension was filtered through Celite and the
solvent was removed under vacuum to yield a crude brown
solid. Subsequent recrystallization attempts from hexanes
produced a yellow solid that was 95% pure by NMR analy-
Structure solution and refinement
Non-hydrogen atomic scattering factors were taken from
the literature tabulations (33). The heavy atom positions
were determined using direct methods employing the
SHELXTL direct-methods routine. The remaining non-
hydrogen atoms were located from successive difference
Fourier map calculations. The refinements were carried out
by using full-matrix least-squares techniques on F, minimiz-
ing the function ω(|Fo| – |Fc|)2, where the weight (ω) is de-
1
sis. Yield: 0.155 g, 0.336 mmol, 59%. H NMR δ: 8.39 (d,
1H, JH-H = 4 Hz, Py), 7.61 (d, 1H, JH-H = 6 Hz, Py), 7.16
3
3
2
(m, 1H, Py), 6.63 (m, 1H, Py), 3.35 (d, 2H, JP-H = 12 Hz,
CH2), 2.04 (s, 15H, Cp*), 1.21 (d, 18H, 3JP-H = 14 Hz, t-Bu),
0.41 (s, 6H, TiMe2). 13C{1H} NMR δ: 156.2 (d, JP-C
=
2
6 Hz, Py, (ipso-C)), 149.6 (s, Py), 135.9 (s, Py), 127.1 (s,
Py), 122.0 (s, Py), 118.8 (s, Cp*), 44.5 (s, TiMe2, 39.4 (d,
1JP-C = 54 Hz, t-Bu), 36.1 (d, 1JP-C = 45 Hz, CH2), 28.2 (s, t-
Bu), 12.6 (s, Cp*). 31P{1H} NMR δ: 22.9 (s). Elemental
anal. calcd.: C 67.23, H 9.76, N 6.03; found: C 66.16,
H 9.97, N 6.25.
2
2
fined as 4Fo /2σ(Fo ) and Fo and Fc are the observed and
calculated structure factor amplitudes, respectively. In the fi-
nal cycles of each refinement, all non-hydrogen atoms were
assigned anisotropic temperature factors in the absence of
disorder or insufficient data. In the latter cases, atoms were
treated isotropically. C-H atom positions were calculated and
allowed to ride on the carbon to which they are bonded, as-
suming a C—H bond length of 0.95 Å. H-atom temperature
factors were fixed at 1.10 times the isotropic temperature
factor of the C-atom to which they are bonded. The H-atom
contributions were calculated, but not refined. The locations
of the largest peaks in the final difference Fourier map cal-
culation, as well as the magnitude of the residual electron
densities in each case, were of no chemical significance. Ad-
ditional details are provided in the supplementary data.2
Polymerization protocol
Polymerization experiments were performed using a glass
Büchi polymerization reactor. Toluene (600 mL) was trans-
ferred into the reactor, heated to 30 °C
2 °C, and
presaturated with ethylene prior to injection of catalyst and
cocatalyst. The solution was stirred at 1000 rpm for the du-
ration of the polymerization experiment. At the end of the
experiments, the polymer was collected and treated as previ-
ously described (9). For the catalyst precursors (5–10), poly-
merization experiments were conducted for 30 min
employing MAO as the cocatalyst. In these polymerizations,
500 equiv. of MAO was injected into the reactor and the so-
lution was stirred for 5 min prior to injecting a toluene solu-
tion of the precatalyst. Catalyst concentrations of
100 µmol/L were employed, thus 0.060 mmol of catalyst in
Results and discussion
The phosphinimine ligands, Me3SiNPR2(2-CH2Py) (R = i-
Pr (3) (32), t-Bu (4)), were prepared in conventional fashion
2 Supplementary data for this article are available on the journal Web site (http://canjchem.nrc.ca) or may be purchased from the Depository
of Unpublished Data, Document Delivery, CISTI, National Research Council Canada, Ottawa, ON K1A 0R6, Canada. DUD 5031. For more
information on obtaining material refer to http://cisti-icist.nrc-cnrc.gc.ca/irm/unpub_e.shtml. CCDC 233404–233407 contain the crys-
tallographic data for this manuscript. These data can be obtained, free of charge, via http://www.ccdc.cam.ac.uk/conts/retrieving.html
(Or from the Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax +44 1223 336033; or
deposit@ccdc.cam.ac.uk).
© 2006 NRC Canada

758
Can. J. Chem. Vol. 84, 2006
Scheme 1.
Table 1. Crystallographic data for 5–8.
5
6
7
8
Formula
C17H25Cl2N2PTi
C19H29Cl2N2PTi
C22H35Cl2N2PTi
C24H39Cl2N2PTi
Formula weight
a (Å)
b (Å)
c (Å)
β (°)
Crystal system
Space group
Volume (Å3)
Dcalcd (g cm–3)
407.16
435.21
477.29
505.34
26.51(1)
8.170(4)
18.58(1)
97.87(1)
Monoclinic
C2/c
9.745(6)
12.713(8)
17.94(1)
98.34(1)
Monoclinic
P21/n
20.41(1)
7.769(4)
16.455(9)
102.29(1)
Monoclinic
P21/c
9.773(5)
17.010(9)
16.414(9)
99.04(1)
Monoclinic
P21/c
3987(4)
1.357
2199(2)
1.314
2549(2)
1.244
2695(3)
1.246
Z
8
4
4
4
Abs. coeff. (µ, mm–1)
θ Range (°)
Total reflections
0.778
2.21–23.29
8193
0.710
1.97–23.24
9012
0.618
2.04–23.38
10 674
3676
0.589
1.74–23.23
11 234
3839
2
2
Data Fo > 3σ(Fo )
2839
3138
Parameters
R (%)
Rw (%)
208
0.0312
0.0849
226
0.0351
0.0909
253
0.0554
0.1270
271
0.0349
0.0895
Goodness-of-fit
1.010
1.026
0.859
1.031
Note: Data collected at 20 °C; Mo Kα radiation (λ = 0.710 69 Å); R = Σ||Fo| – |Fc||/Σ|Fo|; Rw = [Σ(|Fo| – |Fc|)2/Σ|Fo|2]1/2
.
from reaction of the precursor phosphines (30) with Me3SiN3
in toluene at refluxing temperatures. These products were
Cp*TiCl3, respectively (Scheme 1). Similar preparative
methods for species of the form Cp′Ti(NPR3)Cl2 have been
previously described (9). Spectroscopic data for 5–8 were as
expected and elemental analyses were consistent with the
formulations. Single crystal X-ray data were also obtained
for these complexes (Table 1) (Fig. 1). All of these com-
plexes are monomeric as expected, with pseudo-tetrahedral
geometries at Ti with the coordination sphere comprised of a
η5-bound Cp or Cp* ligand, an N-bound phosphinimide, and
1
characterized by H, 31P{1H}, and 13C{1H} NMR spectros-
copy, and all data were consistent with the proposed formu-
lation. The corresponding Ti complexes, Cp′TiCl2[NPR2(2-
CH2Py)] (Cp′ = Cp, R = i-Pr (5), t-Bu (6); Cp′ = Cp*, R =
i-Pr (7), t-Bu (8)), were prepared via reaction of the
phosphinimine ligands, Me3SiNPR2(2-CH2Py) (R = i-Pr (3)
(32), R = t-Bu (4)), with the precursors CpTiCl3 and
© 2006 NRC Canada

Beddie et al.
759
Table 2. Metric parameters (bond lengths and angles) for 5–8.
Fig. 1. ORTEP diagrams (30% probability ellipsoids) of (a) 5,
(b) 6, (c) 7, (d) 8. Hydrogen atoms have been omitted for clarity.
5
6
7
8
Bond lengths (Å)
Ti1—N1
N1—P1
Ti1—Cl1
Ti1—Cl2
1.768(2)
1.761(2)
1.609(2)
2.315(1)
2.331(1)
1.775(4)
1.599(4)
2.307(2)
2.319(2)
1.792(2)
1.597(2)
2.330(1)
2.323(1)
1.607(2)
2.337(1)
2.320(1)
Bond angles (°)
Ti1-N1-P1
N1-Ti1-Cl1
N1-Ti1-Cl2
Cl1-Ti1-Cl2
173.8(1)
170.9(2)
165.2(3)
166.5(2)
104.18(9)
101.47(8)
103.12(8) 103.24(8) 102.8(1)
102.70(7) 104.23(8) 103.0(2)
101.48(3)
99.54(6) 101.31(9) 100.70(4)
Table 3. Ethylene polymerization data and MAO activation.
Activity
(g mmol–1 h–1 atm–1)
Mn
23 700
37 700
22 500
81 400
112 400
67 000
Mw
Precat.
PDI
5
6
7
8
9
10
635 400
417 300
229 300
323 000
556 900
534 800
26.8
11.1
10.2
4
5
8
19
5.6
3
0.89
7.7
2
Note: Conditions for polymerization: ethylene pressure = 2 atm, T =
30 °C, toluene, [catalyst] = 100 µmol/L, 500 equiv. MAO.
pounds 5 and 6 (1.607(2) and 1.609(2) Å) are longer than
those for 7 and 8 (1.600(4) and 1.597(2) Å). The orientation
of the pyridyl substituent of the phosphinimide ligands var-
ies. In 5 and 6, this substituent is oriented in the general di-
rection of the Cp ligand, while in 7 and 8, it projects away
from the Cp* ligand. This is presumably a steric effect. No
preferred orientation of the nitrogen atom of the pyridyl
group is observed and there is no intra- or inter-molecular
interactions of this donor atom with the Lewis acidic Ti cen-
ter.
Polymerization
The complexes 5–8 were tested as ethylene polymeriza-
tion precatalysts using a Büchi polymerization reactor at
30 °C for 30 min in toluene, under an atmosphere of 2 atm
of ethylene (1 atm = 101.325 kPa). A precatalyst concentra-
tion of 100 µmol/L was used and 500 equiv. of MAO was
used as cocatalyst (Table 3). The resulting polymers have
molecular weight (Mw) ranges from approximately 200 000
to 600 000 g/mol with polydispersity indices (PDI) varying
from 4 to 26. These relatively high molecular weights to-
gether with high PDIs suggest that there may be several ac-
tive catalyst species generated in solution. Certainly, these
species do not behave as single site catalysts, nonetheless,
such systems are of interest as they may provide polymers
with desirable processability. In terms of activities, complex
5 displayed moderate activity (18 g mmol–1 h–1 atm–1), while
complexes 6–8 showed low activity. These results stand in
contrast to previous results that demonstrated a high activity
catalyst was derived from CpTiCl2(NP-t-Bu3) under similar
conditions (4, 9). These data also contrast the polymeriza-
tion activity observed for Cp*TiCl2[NP(t-Bu)2(CH2Ph)] un-
der similar conditions (142 g mmol–1 h–1 atm–1) (38). Clearly,
two chloride ligands. Metric parameters (Table 2) are similar
to those reported for related compounds (4, 9, 34–37). The
P-N-Ti bond angles for complexes 5–8 are approximately
linear at 173.8(1)°, 170.9(2)°, 165.0(3)°, and 166.5(2)°,
respectively, and are within the range of 158.7(1)° to
178.38(11)° for related titanium phosphinimide compounds
(34, 37). The smaller P-N-Ti angles for 7 and 8 are attribut-
able to the greater electron donation and steric demand of
the Cp* ligand. This view is also consistent with the longer
Ti—N distances for complexes 7 and 8 (1.775(4) and
1.792(2) Å) compared with those in 5 and 6 (1.768(2) and
1.761(2) Å). Similarly, the P—N bond lengths for com-
© 2006 NRC Canada

760
Can. J. Chem. Vol. 84, 2006
Scheme 2.
Table 4. Ethylene polymerization data and B(C6F5)3 activation.
the only structural difference between 8 and Cp*TiCl2[NP(t-
Bu)2(CH2Ph)] is the N atom of the pyridine ring, and thus
efforts to query the role of this atom were undertaken.
B(C6F5)3
(equiv.)
Activity
Precat.
(g mmol–1 h–1 atm–1)
1
2
10
47
120
75
11
11
11
B(C6F5)3 adducts
In an attempt to sequester any potential interference of the
pyridyl group in the polymerization process, the complexes
5 and 6 were treated with B(C6F5)3 producing donor–
Note: Conditions for polymerization: ethylene pressure = 2 atm, T =
30 °C, toluene, [catalyst] = 20 µmol/L, [TiBAl] = 400 µmol/L, 10 min.
acceptor
complexes
of
the
general
formula,
CpTiCl2[NPR2(2-CH2Py)]·B(C6F5)3 (R = i-Pr (9), t-Bu (10)
Reaction of MeMgX with 5–7 resulted in mixtures of
products that could not be separated despite exhaustive at-
tempts to effect extraction, selective precipitation, or crystal-
lization. These difficulties are thought to arise from the known
acidity of the methylene protons of the pyridyl-phosphinimide
ligand. For example, it is known that reaction of n-BuLi with
3 results in the formation of Li(THF)2[Me3SiNP(i-Pr)2(2-
CHPy)] (32). Nonetheless, the species Cp*TiMe2[NP(t-
Bu)2(2-CH2Py)] (11) (Scheme 1) was successfully produced
from reaction of MeMgCl with 8, although multiple extrac-
tions with hexanes and subsequent reprecipitations were re-
quired to effect adequate purification.
Ethylene polymerization catalysis were examined using
11 and 1, 2, and 10 equiv. of B(C6F5)3 as a cocatalyst (Ta-
ble 4). These data reveal that 11–B(C6F5)3 is a much more
active catalyst system than those derived from 8–MAO. In-
terestingly, increasing the amount of borane from 1 to
2 equiv. prompted an increase in the polymerization activity
from 47 to 120 g mmol–1 h–1 atm–1. In the presence of a
larger excess of B(C6F5)3, i.e., 10 equiv., a polymerization
activity of 75 g mmol–1 h–1 atm–1 was observed. Molecular
weight distributions (GPC analysis) in these polymerizations
were precluded by solubility problems, presumably a result
of polymer molecular weights exceeding the limit of the in-
strumentation (i.e., >1 000 000 g mol–1). It is noteworthy
1
(Scheme 1). 31P{1H}, H, 19F, and 13C{1H} NMR data were
consistent with the formulation. In particular, the 19F{1H}
NMR spectra revealed 15 resonances for both 9 and 10, indi-
cating complexation and the inequivalence of all F atoms in
1
the B(C6F5)3 fragment. The downfield H NMR shifts of the
protons ortho to N in 5 and 6 upon reaction with the borane
were greater than 1 ppm, consistent with B—N donor–
acceptor bond formation. It is a noteworthy comparison that
no reaction is observed between CpTiCl2(NP-t-Bu3) and
B(C6F5)3 at 25 °C (39). The proposed structures of 9 and 10
were not confirmed crystallographically, despite numerous
attempts to acquire suitable crystals.
The species 9 and 10 were evaluated as precatalysts for
ethylene polymerization activity. Aliquots of the freshly pre-
pared solutions were employed. The polymerization experi-
ments were conducted in an identical fashion to those
described previously (Table 3). The resulting activities of the
catalysts derived from 9 and 10 were significantly lower
than those derived from 5 and 6, respectively. However, the
causes of these observations remain unclear. It is likely that
MAO competes with B(C6F5)3 for coordination to the
pyridyl N. Thus, the notion that one might use of coordina-
tion of borane to the pyridyl group to provide a sterically
crowded phosphinimide ligand in situ is clearly simplistic.
© 2006 NRC Canada

Beddie et al.
761
12. R.B. Wilson, Jr. PCT Int. Application, WO 5892079, 1999.
13. M.S.A. Kunzel, F.-Q. Liu, H.W. Roesky, M. Noltemeyer, H.-G.
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has previously been shown to give rise to high molecular
weight polymers in comparison to the similar systems in
which MAO was employed as the activator (4–10).
The above polymerization data show that increasing from
1 to 2 equiv. of borane appears to increase the concentration
of the active catalyst, while further increases in cocatalyst
concentration reduce the observed activity. This suggests the
involvement of several equilibria governing the concentra-
tion of the active catalyst(s). While the precise nature of
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exhibit the exceptional activity of previously reported Ti–
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distributions. While the cause of this effect is the subject of
speculation, the potential of a substituent modification ap-
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Acknowledgements
Financial support from the Natural Sciences and Engi-
neering Research Council of Canada (NSERC), NOVA
Chemicals Corporation, and the Ontario Research and De-
velopment Challenge Fund (ORDCF) is gratefully acknowl-
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© 2006 NRC Canada