Altering molecular weight distributions: Benzylphosphinimide titanium complexes as ethylene polymerization catalysts

Article abstract of DOI:10.1139/v04-062

The phosphines and corresponding phosphinimines R₂BnPNSiMe ₃ (R = t-Bu, Cy), p-C₆H₄(CH₂PR ₂)₂ (R = t-Bu (1), Cy (2)), and p-C₆H ₄(CH₂PR₂

Full text of DOI:10.1139/v04-062

1304
Altering molecular weight distributions: Benzyl–
phosphinimide titanium complexes as ethylene
polymerization catalysts
Emily Hollink, Pingrong Wei, and Douglas W. Stephan
Abstract: The phosphines and corresponding phosphinimines R2BnPNSiMe3 (R = t-Bu, Cy), p-C6H4(CH2PR2)2 (R =
t-Bu (1), Cy (2)), and p-C6H4(CH2PR2NSiMe3)2 (R = t-Bu (3), Cy (4)) were prepared in high yields. Subsequent reac-
tion with Ti precursors afforded (R2BnPN)TiCp*Cl2 (Cp* = η-C5Me5; R = t-Bu (5), Cy (6)), (R2BnPN)TiCpCl2 (Cp =
η-C5H5; R = t-Bu (7), Cy (8)), p-C6H4(CH2PR2NTiCp*Cl2)2 (R = t-Bu (9), Cy (10)), and p-C6H4(CH2PR2NTiCpCl2)2
(R = t-Bu (11), Cy (12)). Methylation of the above complexes gave (R2BnPN)TiCp*Me2 (R = t-Bu (13), Cy (14)),
(R2BnPN)TiCpMe2 (R = t-Bu (15), Cy (16)), p-C6H4(CH2PR2NTiCp*Me2)2 (R = t-Bu (17), Cy (18)), and p-
C6H4(CH2PR2NTiCpMe2)2 (R = t-Bu (19), Cy (20)). The activity of these species as catalyst precursors in ethylene
polymerization catalysis was evaluated using Schlenk line and Buchi reactor techniques using activation by
methylaluminoxane (MAO) or [Ph3C][B(C6F5)4]. All these catalysts showed good activities and yield polymers with rel-
atively broad molecular weight distributions. The bimodal polymers derived from catalysts generated using MAO are
proposed to result from additional active species, possibly as a result of reaction of MAO with the benzylic fragments.
X-ray data are reported for 1, 4–8, 10, 12–14, 16, and 18–20.
Key words: phosphinimides, polymerization, catalysis, polyethylene, titanium, polymer molecular weight distributions.
Résumé : On a préparé les phosphines et les phosphinimines correspondantes R2BnPNSMe3 (R = t-Bu, Cy),
p-C6H4(CH2PR2)2 (R = t-Bu (1), Cy (2)), et p-C6H4(CH2PR2NSiMe3)2 (R = t-Bu (3), Cy (4)) avec d’excellents rende-
ments. Les réactions subséquentes avec des précurseurs de Ti ont conduit à la formation des composés
(R2BnPN)TiCp*Cl2 (Cp* = η-C5Me5; R = t-Bu (5), Cy (6)), (R2BnPN)TiCpCl2 (Cp = η-C5H5; R = t-Bu (7), Cy (8)),
p-C6H4(CH2PR2NTiCp*Cl2)2 (R = t-Bu (9), Cy (10)), et p-C6H4(CH2PR2NTiCpCl2)2 (R = t-Bu (11), Cy (12)). Une mé-
thylation subséquente de ces complexes conduit à la formation des composés (R2BnPN)TiCp*Me2, (R = t-Bu (13), Cy
(14)), (R2BnPN)TiCpMe2 (R = t-Bu (15), Cy (16)), p-C6H4(CH2PR2NTiCp*Me2)2 (R = t-Bu (17), Cy (18)), et p-
C6H4(CH2PR2NTiCpMe2)2 (R = t-Bu (19), Cy (20)). On a évalué l’activité de ces espèces comme précurseurs de cata-
lyseurs pour la polymérisation de l’éthylène à l’aide d’une ligne de Schlenk et un réacteur de Büchi et d’une activation
par méthylaluminoxane (MAO) ou du [Ph3C][B(C6F5)4]. Tous ces catalyseurs présentent de bonnes activités et ils
conduisent à la formation de polymères ayant des distributions de poids moléculaires relativement larges. Il est suggéré
que les polymères à deux modes obtenus à l’aide de catalyseurs résultant d’une génération au MAO pourraient provenir
d’espèces actives additionnelles résultant possiblement d’une réaction du MAO avec les fragments benzyliques. On rap-
porte les données cristallographiques pour les composés 1, 4–8, 10, 12–14, 16 et 18–20.
Mots clés : phosphinimides, polymérisation, catalyse, polyéthylène, titane, distributions des poids moléculaires des po-
lymères.
[Traduit par la Rédaction] Hollink et al. 1313
Introduction
that contain bulky phosphinimide ligands. The family of
compounds of the form CpTi(NPR3)Cl2 (Cp = η-C5H5)
yield active ethylene polymerization catalysts upon activa-
tion by methylaluminoxane (MAO) (4–8). Similarly, upon
activation by B(C6F5)3 or Ph3C[B(C6F5)4], the species (t-
Bu3PN)2TiMe2 provides a remarkably active catalyst, pro-
ducing polyethylene of narrow polydispersity and relatively
high molecular weight (9).
Many of the developments in early-transition-metal chem-
istry in recent years have been prompted by attempts to
uncover effective new homogeneous olefin polymerization
catalysts. A number of studies have described non-metallocene
systems based on a variety of novel ancillary ligands (1–3).
Among such systems, we have described titanium catalysts
Narrow polydispersities are typically observed for single-
site or living polymerization catalysts; however, practical ap-
plications often require resins of broader molecular weight
distribution for effective processing and manipulation (10,
11). There are a variety of methods employed to alter both
the molecular weight and the molecular weight distributions
of resins derived from single-site catalysts. These include
controlled hydrogenolysis or hydrolysis of the polymeriza-
Received 31 December 2003. Published on the NRC Research
Press Web site at http://canjchem.nrc.ca on 2 November
2004.
E. Hollink, P. Wei, and D.W. Stephan.1 Department of
Chemistry & Biochemistry, University of Windsor, Windsor,
ON N9B 3P4, Canada.
1Corresponding author (e-mail: stephan@uwindsor.ca).
Can. J. Chem. 82: 1304–1313 (2004)
doi: 10.1139/V04-062
© 2004 NRC Canada

Hollink et al.
1305
Fig. 1. ORTEP drawings of (a) 5, (b) 8, and (c) 12. 30% ther-
Scheme 1.
mal ellipsoids are shown. Hydrogen atoms are omitted for clarity.
tion process (12, 13) or the use of sequential catalyst sys-
tems to produce the desired mixture of polymers (14–16).
Academic studies and industrial developments continue in
this area, with a particular emphasis on bimodal resins (7,
17–28). An alternative approach involves linking single-site
catalysts together (16, 29–31), affording differing catalyst
sites and thus broader molecular weight distributions (32).
Synthetic routes to bimetallic catalyst precursors such as
C6H4((Me3SiN)Zr(NMe2)2)2 (33), C6H4(OMCpX2)2 (M = Ti,
Zr; X = Cl, Me), and (CH2PPh2NCp*TiX2)2 and 2,6-
(C5H3N)(CH2PPh2NCp*TiX2)2 (Cp* = η-C5Me5; X = Cl,
Me) (34) have recently appeared, and some of these com-
pounds were tested for their catalytic activity upon activa-
tion with MAO. However, very poor catalytic activity was
observed, and thus the nature of the resulting polymers has
not been explored. In this paper, we describe the facile syn-
thesis of a series of bimetallic phosphinimide-based titanium
precatalysts and show that these systems provide effective
ethylene polymerization catalysts upon activation by MAO.
Moreover, the influence of the nature of the precatalysts on
the resulting polymer molecular weight distributions is
probed. The implications and ramifications of these data are
discussed.
with these formulations. The X-ray data revealed that in the
solid state, 4 is centrosymmetric with typical P–N and Si–N
bond lengths averaging 1.542(2) and 1.663(3) Å, respec-
tively. The P–N–Si angle was found to range from 153.4(1)°
to 163.5(1)°, which falls within the range of P–N–Si angles
reported in a number of monodentate phosphinimines (37).
Subsequent thermal reaction of the above phosphinimines
with 1 or 2 equiv. of Cp*TiCl3 or CpTiCl3 resulted in the
high-yield formation of (R2BnPN)TiCp*Cl2 (R = t-Bu (5),
Cy (6)), (R2BnPN)TiCpCl2 (R = t-Bu (7), Cy (8)), p-
C6H4(CH2PR2NTiCp*Cl2)2 (R = t-Bu (9), Cy (10)), and p-
C6H4(CH2PR2NTiCpCl2)2 (R = t-Bu (11) or Cy (12)) upon
liberation of Me3SiCl (Scheme 1). While the compounds 9
and 11 were less soluble in benzene than the others, spectro-
scopic data in all cases were consistent with the formula-
tions. X-ray data (Table 1, Fig. 1) were also acquired for
5–8, 10, and 12. Key metric parameters are tabulated in Ta-
ble 2. In all cases, the Ti–N distances fall within the range of
1.764(3)–1.786(2) Å. The P–N–Ti angles in these com-
pounds are approximately linear, ranging from 157.1(3)° to
175.2(1)°. These values are similar to those of 155.4(2)° and
165.7(1)° reported for 2,6-(C5H3N)(CH2PPh2NTiCp*Cl2)2
and are typical of titanium complexes of phosphinimide de-
rivatives (5, 37). Variations in the metric parameters among
these species are consistent with the steric and electronic dif-
ferences between the Cp* and Cp ligands.
Results and discussion
The phosphines and corresponding phosphinimines
R2BnPNSiMe3 (R = t-Bu, Cy) were prepared via a modifica-
tion of a literature procedure (35). The related diphosphines
p-C6H4(CH2PR2)2 (R = t-Bu (1) or Cy (2)) were prepared by
a method analogous to that used for the related meta-
substituted isomers (36). Thus, treatment of p-C6H4(CH2Br)2
with HPR2 (R = t-Bu or Cy) followed by addition of the
base NEt3 afforded 1 and 2 in yields of 88% and 85%, re-
spectively. X-ray data for 1 confirmed the formulation.
These phosphines were oxidized in a conventional manner
with Me3SiN3 to give the species p-C6H4(CH2PR2NSiMe3)2
(R = t-Bu (3), Cy (4)), also in high yields. Spectroscopic
data, as well as X-ray data for compound 4, were consistent
Methylation of the above complexes proceeded in a facile
manner to give (R2BnPN)TiCp*Me2 (R = t-Bu (13), Cy
(14)), (R2BnPN)TiCpMe2 (R = t-Bu (15), Cy (16)), p-
C6H4(CH2PR2NTiCp*Me2)2 (R = t-Bu (17), Cy (18)), and
© 2004 NRC Canada

1306
Can. J. Chem. Vol. 82, 2004
Table 1 Crystallographic data.
1
4
5
6
7
8
10
Formula
C24H44P2
C38H70N2P2Si2 C25H40NCl2PTi C29H44Cl2NPTi C26H36Cl2NPTi C24H34Cl2NPTi C52H82N2Cl2P2Ti2
Formula wt.
a (Å)
b (Å)
c (Å)
α (°)
394.53
6.1600(2)
8.2564(3)
13.5269(6) 17.616(10)
80.1900(10) 106.248(11)
79.0530(10) 104.112(9)
71.0740(10) 103.764(11)
673.08
9.453(6)
14.566(8)
504.35
556.42
512.33
486.29
1034.74
9.743(6)
17.528(11)
16.130(10)
11.359(7)
16.383(10)
16.443(10)
12.3260(18)
11.6587(17)
19.500(5)
11.660(6)
13.481(7)
15.984(8)
15.218(9)
24.238(14)
15.996(9)
β (°)
γ (°))
98.567(12)
102.672(12)
101.975(11)
110.387(10)
Crystal system
Triclinic
634.54(4)
P1
1.032
1
Triclinic
2133(2)
P1
1.048
2
0.184
9172
6063
Monoclinic
2724(3)
P21/c
1.230
4
0.581
11 282
3860
Monoclinic
2985(3)
P21/c
1.238
4
0.537
12 502
4275
Monoclinic
2741.3(9)
P21/c
1.241
4
0.579
13 075
4767
Orthorhombic
2512(2)
P212121
1.286
Monoclinic
5530(5)
P21/c
1.243
4
0.574
22 618
7876
V (Å3)
Space group
δ(calcd.) (g cm–1
Z
µ(Mo Kα) (cm–1
)
4
)
0.177
3184
0.628
10 691
3567
Data collected
2
2
Data Fo > 3σ(Fo ) 2131
Variables
124
397
271
307
280
262
559
Ra
0.0674
0.2067
0.913
0.0372
0.0981
0.903
0.0394
0.1213
1.114
0.0330
0.0889
0.965
0.0361
0.0711
0.840
0.0233
0.0555
0.981
0.0546
0.1515
0.859
b
Rw
GOF
Note: All data collected at 24 °C with Mo Kα radiation (λ = 0.71069 Å).
aR = Σ (||Fo| – |Fc||)/ Σ|Fo|.
bRw = [Σ (ω(Fo2 – Fc2)2)/Σ (ω(Fo2)2)]1/2
.
p-C6H4(CH2PR2NTiCpMe2)2 (R = t-Bu (19), Cy (20)) in iso-
lated yields ranging from 46% to 83%. Each of these
dimethyl derivatives was characterized spectroscopically.
All of these species with the exception of compounds 15 and
17 were also characterized by crystallography (Table 2). In
these structures, the Ti–N distances are slightly elongated in
comparison to those in the corresponding dichloride deriva-
tives. This is consistent with the increased electron density
at the metal center as a result of methylation. The Ti–C bond
lengths are typical, ranging from 2.119(7) to 2.228(3) Å.
The remaining metric parameters of these compounds are
unexceptional.
low pressures of ethylene (1 atm or less) were used;
nonetheless, the data was reproducible within acceptable ex-
perimental errors. The activities reported (Table 3) are aver-
ages of (at least) duplicate runs; however, insufficient
saturation of the catalyst with ethylene may have resulted in
an underestimation of the activity. Nonetheless, in general,
the monometallic catalysts show higher activities, ranging
from 200 to 280 g mmol–1 h–1 atm–1. These activities fall
within the range of those reported previously for a series of
Ti–phosphinimide complexes (5). These values were signifi-
cantly higher than those seen for catalysts derived from the
previously reported bimetallic systems, where the activities
ranged from 20 to 150 g mmol–1 h–1 atm–1. In particular,
these systems stand in contrast to those derived from the re-
lated species (CH2PPh2NTiCp*Cl2)2, which was reported to
exhibit extremely low activities for polymerization (34). The
cause of such differences is not clear; however, the bimetal-
lic systems are much less soluble than the corresponding
monometallic systems. Similarly, this is true for systems in-
corporating Cp rather than Cp* ligands. It is also noteworthy
that in all pairs of analogs, incorporation of the more
sterically demanding substituents (Cp* in place of Cp or t-
Bu in place of Cy) afforded higher catalyst activity. This ob-
servation is consistent with the previously suggested notion
that steric protection of the phosphinimide N atom enhances
activity (4, 38–40).
Olefin polymerization studies
Preliminary evaluation of these compounds as ethylene
polymerization catalysts was performed in 50 mL of toluene
in a Schlenk flask at 25 °C under 1 atm of ethylene and em-
ploying 1000 equiv. of MAO as co-catalyst. These experi-
ments were allowed to run 30 min prior to quenching. The
preliminary Schlenk screenings provided an indication of the
relative polymerization activity (Table 3), revealing that
among the bimetallic systems, precatalyst 19 afforded the
best polymerization activity. While the activities were repro-
ducible, the characteristics of the resulting polyethylene
(MW and polydipersity index (PDI)) differed from those ob-
tained subsequently, under the more controlled conditions in
the Buchi reactor. Such inconsistencies were attributed to the
effects of the heat of polymerization within the small vol-
ume of the Schlenk flask.
The monometallic catalysts derived from 5, 7, and 13 de-
scribed herein yield polyethylene of molecular weights rang-
ing from 239 800 to 628 400 g mmol–1 h–1 atm–1 with PDIs
of 2.8–3.2 in the Buchi reactor. The corresponding bimetal-
lic catalysts, in contrast, provided PE of molecular weights
ranging from 143 300 to 1 416 000 g mmol–1 h–1 atm–1
depending on the precatalyst. These polymers showed
broader bimodal molecular weight distributions (Fig. 2). The
Subsequently, catalysts were tested in a 1-L Buchi reactor
equipped with a temperature control bath and a stirring
mechanism. The conditions in this case included 500 mL of
toluene, 30 °C ( 2 °C) and a much lower concentration of
precatalyst (50 µmol/L). In initial screening experiments,
© 2004 NRC Canada

Hollink et al.
1307
12
13
14
16
18
19
20
C42H62N2Cl4P2Ti2 (2CH2Cl2) C27H46NPTi
C31H50NPTi
C26H40NPTi
C56H94N2P2Ti2@2C6H6
C38H66N2P2Ti2
C52H80N2P2Ti2
1064.32
8.974(5)
11.490(6)
14.905(8)
96.092(10)
105.085(9)
112.201(11)
Triclinic
1337.4(12)
P1
463.52
515.59
445.46
1109.29
708.67
890.92
8.794(5)
9.772(5)
16.678(9)
77.211(10)
79.909(10)
68.500(9)
Triclinic
1293.4(12)
P1
10.037(5)
19.055(10)
15.059(8)
11.613(6)
16.468(8)
16.287(8)
11.729(7)
13.616(8)
16.206(9)
16.526(10)
17.114(10)
24.453(14)
16.290(9)
16.455(9)
15.594(8)
104.047(10)
102.618(9)
106.280(10)
100.865(10)
Monoclinic
2794(3)
P21/c
1.102
4
Monoclinic
3040(3)
P21/c
1.127
4
Orthorhombic
2588(3)
P212121
1.143
Monoclinic
6639(7)
P21/c
1.110
4
Monoclinic
4105(4)
P21/c
1.147
4
1.322
1
1.144
1
4
0.789
5717
3790
0.376
11 755
3986
0.352
12 862
4376
0.404
10 620
3656
0.327
27 145
9431
0.493
17 348
5861
0.404
5554
3672
262
271
307
262
667
397
262
0.0461
0.1317
1.062
0.0408
0.1209
1.056
0.0414
0.1248
0.570
0.0595
0.1196
1.199
0.0510
0.1084
0.693
0.0378
0.1081
1.008
0.0379
0.1080
1.033
Table 2. Selected metric parameters from X-ray structures.
Compd.
Ti—X (X = Cl, Me) (Å)
Ti—N (Å)
N—P (Å)
Ti–N–P (°)
5
6
7
8
10
2.322(1), 2.324(1)
2.317(1), 2.309(1)
2.3072(9), 2.3091(8)
2.313(1), 2.314(1)
2.312(2), 2.328(2)
2.305(2), 2.317(2)
2.303(2), 2.323(1)
2.165(3), 2.228(3)
2.136(3), 2.152(3)
2.131(6), 2.130(6)
2.119(7), 2.145(6)
2.160(6), 2.155(6)
2.137(3), 2.143(3)
2.124(3), 2.130(4)
2.160(3), 2.191(3)
1.786(2)
1.776(2)
1.760(2)
1.765(2)
1.786(5)
1.768(5)
1.764(3)
1.830(2)
1.811(2)
1.804(4)
1.829(5)
1.813(5)
1.806(2)
1.802(2)
1.806(2)
1.598(2)
1.594(2)
1.599(2)
1.607(2)
1.589(5)
1.602(5)
1.608(3)
1.580(2)
1.570(2)
1.579(4)
1.573(5)
1.582(5)
1.582(2)
1.581(2)
1.580(2)
167.6(1)
157.3(1)
175.2(1)
168.4(1)
157.1(3)
162.6(3)
172.7(2)
172.6(2)
162.8(2)
168.1(3)
163.4(4)
161.5(4)
171.0(1)
173.9(2)
167.9(1)
12
13
14
16
18
19
20
separation of the peak molecular weights and the relative in-
tensities of the two modes were catalyst and condition
dependent. For example, the polymer derived from the pre-
catalyst 9 (Fig. 2a) exhibited a bimodal distribution that was
fit with two Gaussian curves of peak molecular weights
98 600 and 447 700 g mmol–1. In contrast, the catalyst de-
rived from 19 (Fig. 2b) gave rise to a polymer with clearly
separated peaks at 19 700 and 537 000 g mmol–1. These
results stand in marked contrast to previous reports regard-
ing compounds of the form (R3PN)TiCpCl2, which upon ac-
tivation by MAO, behave as single-site catalysts providing
polyethylene of high molecular weight with narrow polydis-
persities (5).
(Table 4), polymer with a broaden molecular weight distri-
bution in which a lower molecular weight polymer fraction
is similar to that derived from 9 (Fig. 3) was produced. This
observation seemed to counter the notion that a bimodal
polymer was a direct result of the bimetallic catalysts. Moni-
toring the polymerizations using 5 and 13 over 10-min inter-
vals revealed the initial appearance of a higher molecular
weight fraction that accumulated over time (Fig. 4). This
suggests that the active catalyst undergoes some sort of
transformation during the course of the polymerization, pos-
sibly via reaction of the benzylic protons. It is noteworthy
that Bochmann and co-workers have observed metallation of
the methylene protons of (CH2PPh2NTiCp*Cl2)2 (34).
Related tests done using the monometallic catalyst precur-
sor 5 showed that under 2 atm of constant ethylene pressure
Using similar increased pressure conditions, activation of
the bimetallic catalyst precursors 18 and 20 with 1, 2, or
© 2004 NRC Canada

1308
Can. J. Chem. Vol. 82, 2004
Table 3. Ethylene polymerization data.
Catalyst concn.
Mw
MWc
a
Precatalyst
T (°C)
(µmol L–1)
Activity
(g mol–1)
131 100
—
15 200
—
234 100
138 700
PDIa,b
5.4
(g mol–1)
9
10
11
12
5
17
18
19
36
<1
20
<1
42
93
55
100
11
170
200
25
25
25
25
25
25
25
25
25
25
25
350
350
350
350
350
350
350
350
350
350
350
—
—
—
—
—
—
—
—
—
—
—
d
d
—
4.8
d
d
—
4.35
1.6
e
e
—
—
38 100
536 500
117 400
35 600
2.2
2.0
2.02
2.5
20
13
ZrCp2Cl2
9
10
11
12
5
17
18
19
30
30
30
30
30
30
30
30
30
30
30
50
50
50
50
50
50
50
50
50
50
50
150
85
50
319 200
—
143 300
1 104 000
239 800
3.2
—
98 600, 447 700
—
34 300, 653 100
684 200, 1 407 700
e
e
4.8
1.9
2.8
1.9
25
200
100
92
60
20
—
468 600
299 200, 1 425 600
—
19 700, 537 000
522 400, 1 710 000
—
—
e
e
—
—
195 200
1 416 000
628 400
10.0
3.4
3.2
20
13
ZrCp2Cl2
280
610
340 800
2.1
Note: Ti:Al ratio of 1:500, toluene solvent, 30 min, 1 atm ethylene Activities are in units of g mmol–1 h–1 atm–1.
Limited ethylene supply may result in an underestimation of the activity.
aValues are overall averages observed.
bPDI, polydispersity index.
cPeak molecular weight from nonlinear Gaussian fit.
dToo little polymer to analyze.
ePolymer would not dissolve in solvent.
Table 4. Ethylene polymerization data.
Mn
(g mol–1)
Mw
(g mol–1)
Precatalyst
T (°C)
Co-catalysta
Activity
PDIb
5
5
5
13
13
13
13
10
15
20
10
15
20
30
10
MAO
MAO
MAO
MAO
MAO
MAO
MAO
MAO
1510
1190
1050
1580
1260
1140
780
ZrCp2Me2
1880
ZrCp2Cl2
10
MAO
2030
18
18
18
20
20
20
10
10
10
10
10
10
10
TB (1 equiv)
TB (2 equiv)
TB (4 equiv)
TB (1 equiv)
TB (2 equiv)
TB (4 equiv)
TB (2 equiv)
630
895
525
10
95
126
1030
213 600
126 300
252 200
50 300
628 900
157 500
171 000
566 400
382 300
718 000
206 700
1 270 000
491 000
334 800
2.7
3.0
2.9
4.1
2.0
3.1
1.9
c
ZrCp2Me2
Note: Toluene solvent, 30 °C, 1.82 atm ethylene (constant). Activities are in units of g mmol–1 h–1 atm–1.
aFor MAO activation, Ti:Al or Zr:Al ratio of 1:500; for TB ([Ph3C][B(C6F5)4]), Al(i-Pr)3 scrubber, Ti:Al ratio of 1:5.
bPDI, polydispersity index.
cZr:Al ratio of 1:20.
© 2004 NRC Canada

Hollink et al.
1309
Fig. 2. Observed and two-Gaussian fit of GPC of polyethylene
derived from the precatalysts (a) 9 and (b) 19.
Fig. 3. GPC of polyethylene from catalysts derived from 9 (——)
and derivative 5 (– – –).
Fig. 4. GPC of polyethylene from catalysts derived from 5 as a
function of time.
4 equiv. of [Ph3C][B(C6F5)4] resulted in the efficient poly-
merization of ethylene (Table 4). In general, with an in-
crease in the amount of activator from 1 to 2 equiv.,
polymerization activities also increased. The bulkier Cp* de-
rivative showed 4 times the activity of the Cp analog when 4
equiv. of [Ph3C][B(C6F5)4] were used, and ca. 60 times the
activity when only 1 equiv. of activator was employed. The
resulting polymers showed monodisperse GPC traces with
PDI values less than 4. This is in contrast to the results ob-
tained when MAO was used as an activator.
investigating strategies to other modified catalyst systems in
an effort to understand the relationship between catalyst
structure and polymer properties in more detail.
In conclusion, MAO or [Ph3C][B(C6F5)4] activation of the
monometallic and bimetallic benzyl-phosphinimide catalysts
produced polyethylene with good activities. While all these
catalyst systems gave relatively broad molecular weight dis-
tributions, catalysts generated using MAO gave bimodal
polymers. Given that previous studies have shown that other
phosphinimide catalysts give single-site activity, the present
observations infer that MAO reacts with the present cata-
lysts, probably at the benzylic fragment, to modify the active
species, resulting in two (or more) catalyst sites. While this
postulate remains unconfirmed, it is noteworthy that in re-
lated systems, Bochmann and co-workers (34) have ob-
served metallation of methylene groups in phosphinimide
ligands. While the precise cause remains a subject of investi-
gation, it is clear that modification of the catalyst structure
alters the nature of the resulting polymer. We are currently
Experimental
General data
The syntheses were performed under an atmosphere of
dry, oxygen-free nitrogen in a Vacuum Atmospheres (Haw-
thorne, Calif.) inert atmosphere glove box or by standard
Schlenk techniques. Proton NMR data were acquired on a
Bruker Avance 500-MHz spectrometer, and 13C{1H} and
31P{1H} NMR data on a Bruker Avance 300-MHz spectrom-
eter. Proton and 13C NMR chemical shifts are listed
downfield from SiMe4 in parts per million and were refer-
enced to the residual proton or carbon peak of the solvent.
Phosphorus-31 NMR data were referenced using an external
standard relative to 85% H3PO4. All NMR spectra were
recorded in C6D6 unless otherwise stated. Combustion analy-
ses were performed by Galbraith Laboratories Inc. or in-
© 2004 NRC Canada

1310
Can. J. Chem. Vol. 82, 2004
house elemental analysis services. In a very few cases,
despite repeated analyses and the use of added oxidant, C
analyses yielded deviations from calculated values. We at-
tribute this to partial formation of Ti–C during combustion
of the Ti-organometallic derivatives. Gel permeation chro-
matography (GPC) was performed employing a Waters
150C GPC using 1,2,4-trichlorobenzene as the mobile phase
at 140 °C at NOVA Research and Technology Centre (Cal-
gary, Alta.). The samples were prepared for GPC analyses
by dissolving the polymer in the mobile-phase solvent in an
external oven at 0.1% (w/v) and were filtered before injec-
tion. Molecular weights are expressed as polyethylene
equivalents with a relative standard deviation of 2.9% and
5.0% for Mn and Mw, respectively. Reagent-grade solvents
and NEt3 were purchased from Aldrich Chemical Co. Ben-
zene, toluene, and Et2O were dried over Na, MeOH was
dried over Mg, and NEt3 was dried over KOH prior to distil-
lation. C6D6 and CD2Cl2 were purchased from Cambridge
Isotopes Laboratories (Andover, Mass.) and degassed by at
least 4 freeze/pump/thaw cycles before storing over 4Å mo-
lecular sieves. The compounds R2BnP and R2BnPNSiMe3
(Bn = benzyl; R = t-Bu, Cy) (35) and CpTiCl3 (41) were
prepared according to literature methods, and the phosphines
were prepared via a modification of a literature procedure
(36). The reagents MeMgBr, Me3SiN3, and p-C6H4(CH2Br)2
were purchased from Aldrich Chemical Co., and HP(t-Bu)2,
HPCy2, and Cp*TiCl3 were purchased from Strem Chemical
Co. (Newburyport, Mass.); all were used without further pu-
rification.
pared in a similar manner, and one sample preparation is de-
tailed. Solid 1 (0.69 g, 1.7 mmol) and Me3SiN3 (1.00 g,
8.7 mmol) were combined to generate a slurry. The mixture
was heated at reflux for 15 h, after which time the excess
Me3SiN3 was removed in vacuo. The beige solid was
crushed with a mortar and pestle into a fine powder, washed
with hexanes (3 × 10 mL), and dried in vacuo for an addi-
tional 5 h. Compound 3: Yield 0.88 g, 88%. Crystals suit-
able for X-ray diffraction were grown by slow evaporation
1
from hexanes. H NMR: 7.39 (s, 4H, C6H4), 2.73 (d, 4H,
JP–H = 10 Hz, CH2), 0.99 (d, 36H, JP–H = 13 Hz, t-Bu), 0.35
(s, 18H, Me). 13C{1H} NMR: 133.4 (s, C6H4), 130.4 (s,
C6H4), 37.1 (d, JP–C = 60 Hz, CH2), 30.1 (d, JP–C = 57 Hz,
CH2), 27.6 (s, t-Bu), 1.4 (s, Me3). 31P{1H} NMR: 24.6 (s).
Anal. Calcd. for C30H62N2P2Si2: C 63.33, H 10.98, N 4.92;
found: C 63.34, H 10.36, N 4.93. Compound 4: Yield 2.77 g,
94%. 1H NMR: 7.34 (s, 4H, C6H4), 2.67 (d, 4H, JP–H
=
12 Hz, CH2P), 1.78–1.58 (m, 18H, Cy), 1.45–1.07 (m, 26H,
Cy), 0.41 (s, 18H, Me). 13C{1H} NMR: 132.9 (s, C6H4),
130.1 (s, C6H4), 37.6 (d, JP–C = 65 Hz, Cy), 33.7 (d, JP–C
=
60 Hz, CH2P), 27.2 (d, JP–C = 13 Hz, Cy), 26.5 (s, Cy), 26.2
(s, Cy), 5.2 (s, Me3). 31P{1H} NMR: 13.5 (s). Anal. Calcd.
for C38H70N2P2Si2: C 67.81, H 10.48, N 4.16; found: C
68.08, H 10.85, N 3.89.
Synthesis of (R2BnPN)Cp′TiCl2 (Cp′ = Cp*, Cp; R = t-
Bu, Cy)
Compounds 5 (Cp′ = Cp*; R = t-Bu), 6 (Cp′ = Cp*; R =
Cy), 7 (Cp′ = Cp; R = t-Bu), and 8 (Cp′ = Cp; R = Cy) were
all prepared in a similar manner, and thus only one prepara-
tion is detailed. Solid Cp*TiCl3 (1.12 g, 3.8 mmol) was dis-
solved in toluene (100 mL) to give a clear, red solution.
Liquid (t-Bu)2BnPNSiMe3 (1.24 g, 3.8 mmol) was added
dropwise at 25 °C, and the mixture was stirred for 24 h. The
volatile products were removed in vacuo, and the bright or-
ange solid was washed with hexanes (3 × 10 mL) and dried.
Synthesis of p-C6H4(CH2PR2)2 (R = t-Bu, Cy)
Compounds 1 (R = t-Bu) and 2 (R = Cy) were prepared in
a similar manner to a literature method for the related meta-
substituted analogs (36). p-C6H4(CH2Br)2 (0.88 g,
3.3 mmol) was slurried in MeOH, and HP(t-Bu)2 (1.08 g,
7.3 mmol) was added via syringe. The mixture was stirred at
25 °C for 16 h, during which time the mixture became a ho-
mogeneous solution. NEt3 (0.74 g, 7.3 mmol) was added via
syringe, and a fine white solid precipitated from solution.
The solid was washed with MeOH (3 × 20 mL) and dried in
vacuo for 5 h. A second crop was obtained by concentrating
the mother liquor and precipitating the product with de-
gassed water; no degradation in purity was evidenced by the
1H NMR spectrum. Compound 1: White solid. Yield 1.16 g
(88%). 1H NMR: 7.38 (s, 4H, C6H4), 2.73 (s, 4H, CH2), 1.06
(d, 36H, JP–H = 10 Hz, t-Bu). 13C{1H} NMR: 138.4 (s,
C6H4), 130.1 (s, C6H4), 32.1 (d, JP–C = 54 Hz, t-Bu), 30.1 (s,
t-Bu), 29.0 (d, JP–C = 48 Hz, CH2). 31P{1H} NMR: 33.4 (s).
Crystals suitable for X-ray diffraction were grown by slow
evaporation from benzene. Anal. Calcd. for C24H44P2: C
73.06, H 11.24; found: C 72.36, H 11.05. Compound 2:
White solid. Yield 4.23 g, 85%. 1H NMR: 7.33 (s, 4H,
C6H4), 2.72 (s, 4H, CH2P), 1.80–1.51 (m, 18H, Cy), 1.25–
1.12 (m, 26H, Cy). 13C{1H} NMR: 137.9 (s, C6H4), 129.7
(s, C6H4), 34.0 (d, JP–C = 17 Hz, Cy), 30.3 (d, JP–C = 14 Hz,
CH2P), 29.7 (d, JP–C = 10 Hz, Cy), 27.6 (s, Cy), 26.9 (s, Cy).
31P{1H} NMR: 1.2 (s). Anal. Calcd. for C32H52P2: C 77.07,
H 10.51; found: C 76.42, H 10.68.
1
Compound 5: Yield 1.73 g, 91%. H NMR: 7.39 (d, 2H,
JH–H = 8 Hz, C6H5), 7.19 (t, 2H, JH–H = 8 Hz, Ph), 7.08 (t,
1H, JH–H = 8 Hz, Ph), 2.92 (d, 2H, JP–H = 12 Hz, CH2), 2.21
(s, 15H, Cp*), 1.10 (d, 18H, JP–H = 14 Hz, Pt-Bu2). 13C{1H}
NMR: 140.8 (s, Ph), 131.2 (s, Ph), 128.7 (s, Ph), 127.1 (s,
Ph), 125.9 (s, Cp*), 39.6 (d, JP–C = 52 Hz, t-Bu), 30.9 (d,
JP–C = 48 Hz, CH2), 27.8 (s, t-Bu), 13.1 (s, Cp*). 31P{1H}
NMR: 35.3 (s). Anal. Calcd. for C25H40Cl2NPTi: C 59.54, H
7.99, N 2.78; found: C 59.74, H 7.88, N 2.95. Crystals suit-
able for X-ray diffraction were grown by slow evaporation
from benzene. Compound 6: Bright orange solid. Yield
1
3
580 mg, 93%. H NMR δ: 7.20 (d, 2H, JH–H = 8 Hz, Ph (o-
3
H)), 7.15 (dd, 2H, JH–H = 8 Hz, Ph (m-H)), 7.04 (t, 1H,
3JH–H = 8 Hz, Ph (p-H)), 3.01 (d, 2H, JP–H = 14 Hz, CH2P),
2
2.20 (s, 15H, Cp*), 1.71–0.96 (m, 22H, Cy). 13C{1H} NMR
2
3
δ: 132.6 (d, JP–C = 7 Hz, Ph (ipso-C)), 130.5 (d, JP–C
=
5 Hz, Ph (o-C)), 128.9 (s, Ph (m-C)), 127.2 (s, Ph (p-C)),
125.9 (s, Cp*), 37.2 (d, 1JP–C = 59 Hz, Cy (ipso-C)), 32.2 (d,
1JP–C = 52 Hz, CH2P), 26.8 (d, JP–C = 12 Hz, Cy (o-C)),
2
2
26.7 (d, JP–C = 12 Hz, Cy (o-C)), 26.1 (s, Cy (m-C)), 26.0
(s, Cy (p-C)), 13.2 (s, Cp*). 31P{1H} NMR δ: 23.0 (s). Anal.
Calcd. for C29H44Cl2NPTi: C 62.60, H 7.97, N 2.52; found:
C 62.29, H 8.27, N 2.45. Orange crystals suitable for X-ray
diffraction were grown by slow diffusion of pentanes/hexanes
into benzene. Compound 7: Bright yellow solid. Yield
Synthesis of p-C6H4(CH2PR2NSiMe3)2 (R = t-Bu, Cy)
Compounds 3 (R = t-Bu) and 4 (R = Cy) were both pre-
© 2004 NRC Canada

Hollink et al.
1311
1
3
0.390 g, 77%. H NMR δ: 7.26 (d, 2H, JH–H = 8 Hz, Ph),
C 51.67, H 6.89, N 3.54; found: C 52.65, H 7.64, N 3.45.
Compound 12: Light yellow solid. Yield 1.36 g, 95%. H
3
3
1
7.20 (t, 2H, JH–H = 8 Hz, Ph), 7.07 (t, 1H, JH–H = 8 Hz,
Ph), 6.22 (s, 5H, Cp), 2.61 (d, 2H, 2JP–H = 10 Hz, CH2), 1.04
NMR: 7.46 (s, 4H, C6H4), 6.39 (s, 10H, Cp), 3.21 (d, 4H,
JP–H = 12 Hz, CH2P), 1.96–1.27 (m, 44H, Cy). 13C{1H}
NMR: 131.8 (s, C6H4), 131.5 (s, C6H4), 115.7 (s, Cp), 37.1
(d, JP–C = 58 Hz, Cy), 31.1 (d, JP–C = 53 Hz, CH2P), 27.0 (d,
JP–C = 13 Hz, Cy), 26.3 (s, Cy), 26.3 (s, Cy). 31P{1H} NMR:
27.0 (s). Anal. Calcd. for C42H62Cl4N2P2Ti2: C 56.40, H
6.99, N 3.13; found: C 56.23, H 7.00, N 3.36. Crystals suit-
able for X-ray diffraction were grown by slow evaporation
from CH2Cl2.
(d, 18H, JP–H = 15 Hz, t-Bu). 13C{1H} NMR δ: 131.5 (d,
3
2JP–C = 5 Hz, (ipso-C)), 128.7 (d, 3JP–C = 5 Hz, (o-C)), 128.6
1
(s, Ph), 128.3 (s, Ph), 115.5 (s, Cp), 39.3 (d, JP–C = 51 Hz,
1
t-Bu), 28.9 (d, JP–C = 47 Hz, CH2), 27.2 (s, t-Bu). 31P{1H}
NMR δ: 34.9 (s). Anal. Calcd. for C20H30Cl2NPTi: C 55.32,
H, 6.96, N 3.23; found: C 55.49, H, 7.14, N 3.19. Crystals
suitable for X-ray diffraction were grown by slow evapora-
tion from benzene. Compound 8: Bright yellow solid. Yield
1
3
685 mg, 92%. H NMR δ: 7.27 (d, 2H, JH–H = 8 Hz, Ph (o-
3
H)), 7.18 (dd, 2H, JH–H = 8 Hz, Ph (m-H)), 7.06 (t, 1H,
3JH–H = 8 Hz, Ph (p-H)), 6.38 (s, 5H, Cp), 2.65 (d, 2H,
2JP–H = 13 Hz, CH2P), 1.74–0.84 (m, 22H, Cy). 13C{1H}
Synthesis of (R2BnPN)TiCp′Me2 (Cp′ = Cp*, Cp; R = t-
Bu, Cy)
NMR δ: 131.6 (d, 2JP–C = 8 Hz, Ph (ipso-C)), 130.8 (d, 3JP–C
=
Compounds 13 (Cp′ = Cp*; R = t-Bu), 14 (Cp′ = Cp*; R =
Cy), 15 (Cp′ = Cp; R = t-Bu), and 16 (Cp′ = Cp; R = Cy)
were all prepared in a similar manner, and thus only the
preparation of 13 is detailed. Compound 5 (160 mg,
0.32 mmol) was slurried in Et2O (15 mL), and a 3.0 mol L–1
solution of MeMgBr in the same solvent (2.24 mL,
0.67 mmol) was added dropwise via syringe at 25 °C. The
heterogeneous solution was stirred for 15 h, after which time
the solvent was removed in vacuo. Extraction with hexanes
(3 × 10 mL) and filtration through Hyflo Super Cel® (Beaver
Chemicals, Burlington, Ont.) afforded a bright yellow solu-
tion. Subsequent removal of the solvent in vacuo generated
bright yellow crystals of 13. Yield 122 mg, 83%. 1H NMR δ:
5 Hz, Ph (o-C)), 128.9 (s, Ph (m-C)), 128.5 (s, Ph (p-C)),
1
115.2 (s, Cp), 36.6 (d, JP–C = 58 Hz, Cy (ipso-C)), 30.9 (d,
1JP–C = 52 Hz, CH2P), 26.6 (d, JP–C = 13 Hz, Cy (o-C)),
2
25.9 (s, Cy (m-C)), 25.7 (s, Cy (p-C)). 31P{1H} NMR δ: 24.3
(s). Anal. Calcd. for C24H34Cl2NPTi: C 59.27, H 7.05, N
2.88; found: C 59.68, H 7.28, N 2.82. Yellow crystals suit-
able for X-ray diffraction were grown by slow diffusion of
pentanes/hexanes into benzene.
Synthesis of p-C6H4(CH2PR2NTiCp′Cl2)2 (Cp′ = Cp*,
Cp; R = t-Bu, Cy)
3
3
Compounds 9 (Cp′ = Cp*; R = t-Bu), 10 (Cp′ = Cp*; R =
Cy), 11 (Cp′ = Cp; R = t-Bu), and 12 (Cp′ = Cp; R = Cy)
were all prepared in a similar manner, and only one sample
preparation is detailed. Compound 3 (0.81 g, 1.2 mmol) and
Cp*TiCl3 (0.70 g, 2.4 mmol) were slurried in toluene
(80 mL) to afford a bright orange, foggy solution. The mix-
ture was heated at reflux for 15 h, after which time it was
filtered. The filtrate was concentrated to ca. 20 mL, and the
bright orange powder that precipitated was filtered, washed
with benzene (3 × 15 mL), and dried in vacuo. Compound
10: Yield 2.34 g, 95%. 1H NMR (CD2Cl2): 7.48 (s, 4H,
C6H4), 3.38 (d, 4H, JP–H = 12 Hz, CH2), 2.14 (s, 30H, Cp*),
1.34 (d, 36H, JP–H = 15 Hz, t-Bu). 13C{1H} NMR (CD2Cl2):
133.4 (s, C6H4), 131.5 (s, C6H4), 123.2 (s, Cp*), 40.6 (s,
CH2), 39.8 (d, JP–C = 55 Hz, t-Bu), 28.3 (s, t-Bu), 8.9 (s,
Cp*). 31P{1H} NMR (CD2Cl2): 37.2 (s). Anal. Calcd. for
C44H74Cl4N2P2Ti2: C 56.79, H 8.02, N 3.01; found: C 54.92,
H 8.16, N 3.35. Compound 10: Bright orange solid. Yield
7.38 (d, 2H, JH–H = 8 Hz, Ph (o-H)), 7.15 (dd, 2H, JH–H =
3
8 Hz, Ph (m-H)), 7.08 (t, 1H, JH–H = 8 Hz, Ph (p-H)), 2.90
2
(d, 2H, JP–H = 12 Hz, CH2), 2.03 (s, 15H, Cp*), 1.16 (d,
18H, JP–H = 14 Hz, t-Bu), 0.39 (s, 6H, TiMe). 13C{1H}
3
2
NMR δ: 135.0 (d, JP–C = 7 Hz, Ph (ipso-C)), 130.9 (d,
3JP–C = 5 Hz, Ph (o-C)), 128.3 (s, Ph (m-C)), 126.7 (s, Ph (p-
C)), 118.5 (s, Cp*), 44.4 (s, TiMe), 39.0 (d, 1JP–C = 54 Hz, t-
1
Bu), 31.6 (d, JP–C = 48 Hz, CH2), 28.0 (s, t-Bu), 12.2 (s,
Cp*). 31P{1H} NMR δ: 21.4 (s). Anal. Calcd. for
C27H46NPTi: C 69.96, H 10.00, N 3.02; found: C 69.59, H
10.03, N 3.02. Yellow crystals suitable for X-ray diffraction
were grown by slow evaporation from hexanes. Compound
1
14: Light yellow solid. Yield 100 mg, 47%. H NMR δ: 7.28
3
3
(d, 2H, JH–H = 8 Hz, Ph (o-H)), 7.17 (dd, 2H, JH–H = 8 Hz,
Ph (m-H)), 7.06 (t, 1H, 3JH–H = 8 Hz, Ph (p-H)), 2.93 (d, 2H,
2JP–H = 13 Hz, CH2P), 2.08 (s, 15H, Cp*), 1.91–1.03 (m,
22H, Cy), 0.45 (s, 6H, TiMe). 13C{1H} NMR δ: 134.2 (d,
2JP–C = 7 Hz, Ph (ipso-C)), 130.3 (d, JP–C = 5 Hz, Ph (o-
3
1
0.98 g, 79%. H NMR: 7.36 (s, 4H, C6H4), 3.01 (d, 4H,
C)), 128.6 (s, Ph (m-C)), 126.8 (s, Ph (p-C)), 118.5 (s, Cp*),
1
1
JP–H = 13 Hz, CH2P), 2.24 (s, 30H, Cp*), 1.71–1.45 (m,
42.6 (s, TiMe), 38.1 (d, JP–C = 60 Hz, Cy), 34.4 (d, JP–C
=
=
18H, Cy), 1.18–1.03 (m, 26H, Cy). 13C{1H} NMR: 137.4 (s,
52 Hz, CH2P), 27.0 (d, JP–C = 3 Hz, Cy), 26.8 (d, JP–C
2
2
C6H4), 131.0 (s, C6H4), 125.8 (s, Cp*), 37.2 (d, JP–C
59 Hz, Cy), 31.9 (d, JP–C = 52 Hz, CH2P), 26.8 (d, JP–C
=
=
3 Hz, Cy), 26.4 (s, Cy), 26.3 (s, Cy), 12.3 (s, Cp*). 31P{1H}
NMR δ: 8.4 (s). Anal. Calcd. for C31H50NPTi: C 72.22, H,
9.77, N 2.72; found: C 71.93, H, 10.10, N 2.52. Yellow–
orange crystals suitable for X-ray diffraction were grown by
slow evaporation from pentanes. Compound 15: Beige solid.
Yield 74 mg, 78%. 1H NMR δ: 7.32 (d, 2H, 3JH–H = 7 Hz, Ph
12 Hz, Cy), 26.1 (s, Cy (m-C)), 26.1 (s, Cy), 13.2 (s, Cp*).
31P{1H} NMR: 22.4 (s). Anal. Calcd. for C52H82Cl4N2P2Ti2:
C 60.36, H 7.99, N 2.71; found: C 60.20, H 8.19, N 2.76.
Crystals suitable for X-ray diffraction were grown by slow
evaporation from toluene. Compound 11: Yellow solid.
3
(o-H)), 7.16 (dd, 2H, JH–H = 7 Hz, Ph (m-H)), 7.05 (t, 1H,
1
Yield 2.34 g, 95%. H NMR (CD2Cl2): 7.54 (s, 4H, C6H4),
3JH–H = 7 Hz, Ph (p-H)), 6.08 (s, 5H, Cp), 2.74 (d, 2H,
3
6.29 (s, 10H, C5H5), 3.31 (d, 4H, JP–H = 10 Hz, CH2), 1.40
(d, 36H, JP–H = 13 Hz, t-Bu). 13C{1H} NMR (CD2Cl2):
132.7 (s, C6H4), 132.0 (s, C6H4), 116.0 (s, Cp), 46.4 (s,
CH2), 40.0 (d, JP–C = 51 Hz, t-Bu), 27.8 (s, t-Bu). 31P{1H}
NMR (CD2Cl2): 38.7 (s). Anal. Calcd. for C34H54Cl4N2P2Ti2:
2JP–H = 11 Hz, CH2), 1.06 (d, 18H, JP–H = 14 Hz, t-Bu),
0.70 (s, 6H, TiMe). 13C{1H} NMR δ: 134.0 (s, Ph (ipso-C)),
131.1 (d, 3JP–C = 4 Hz, Ph (o-C)), 128.4 (s, Ph (m-C)), 126.8
1
(s, Ph (p-C)), 111.1 (s, Cp), 41.4 (s, TiMe), 38.5 (d, JP–C
54 Hz, t-Bu), 30.2 (d, JP–C = 48 Hz, CH2), 27.5 (s, t-Bu).
=
1
© 2004 NRC Canada

1312
Can. J. Chem. Vol. 82, 2004
31P{1H} NMR (121.5 MHz, C6D6) δ: 21.6 (s). Anal. Calcd.
for C22H36NPTi: C 67.17, H 9.22, N 3.56; found: C 67.09, H
9.03, N 3.02. Compound 16: Beige solid. Yield 230 mg,
Cy), 32.4 (d, JP–C = 53 Hz, CH2P), 26.9 (d, JP–C = 12 Hz,
Cy), 26.3 (s, Cy), 26.1 (s, Cy). 31P{1H} NMR: 10.1 (s).
Anal. Calcd. for C52H80N2P2Ti2: C 70.10, H 9.05, N 3.14;
found: C 70.30, H 9.45, N 3.06. Crystals suitable for X-ray
diffraction were grown by slow evaporation from benzene.
1
3
46%. H NMR δ: 7.33 (d, 2H, JH–H = 8 Hz, Ph (o-H)), 7.18
3
3
(dd, 2H, JH–H = 8 Hz, Ph (m-H)), 7.06 (t, 1H, JH–H = 8 Hz,
2
Ph (p-H)), 6.18 (s, 5H, Cp), 2.71 (d, 2H, JP–H = 13 Hz,
CH2P), 1.62–0.98 (m, 22H, Cy), 0.73 (s, 6H, TiMe).
Polymerization protocol
2
13C{1H} NMR δ: 133.5 (d, JP–C = 7 Hz, Ph (ipso-C)), 130.5
Two protocols were employed. In the first, a Schlenk flask
was charged with toluene (50 mL) and MAO (1000 equiv.,
10% in toluene), and the solution was presaturated with the
monomer by briefly evacuating/backfilling (4×) and then
stirring under an atmosphere of C2H4 for 5 min. A toluene,
solution of the catalyst precursor (350 µmol) was injected,
and the mixture was stirred at 25 °C for 30 min. The reac-
tion was quenched with 1 mol/L HCl in MeOH, and the pre-
cipitated polymer was subsequently washed with HCl,
HCl/MeOH, and toluene before drying at 50 °C for at least
48 h prior to weighing. In the second protocol, a 1-L Buchi
reactor was dried in vacuo (10–2 mm Hg (1 mm Hg =
133.322 Pa)) for several hours. Toluene (500 mL) was trans-
ferred into the vessel under a positive pressure of N2 and
was heated to 30°C. The temperature was controlled (to ca.
2 °C) with an external heating/cooling bath and was moni-
tored by a thermocouple that extended into the polymeriza-
tion vessel. The vessel was vented of N2 and then
pressurized with C2H4 (12 psig) while the solvent stirred at a
rate of 150 rpm. A solution of MAO (1000 equiv., 10% in
toluene) was injected and the mixture was stirred for 5 min.
A toluene solution, of the precatalyst (50 µmol) was in-
jected, the rate of stirring was increased to 1000 rpm, and
the solution was stirred for 30 min. Any recorded exotherm
was within the allowed temperature differential of the
heating/cooling system. The quenching of the reaction and
the collection/treatment of the polymer were as described
above.
(d, 3JP–C = 5 Hz, Ph (o-C)), 128.5 (s, Ph (m-C)), 127.0 (s, Ph
1
(p-C)), 110.8 (s, Cp), 40.7 (s, TiMe), 37.6 (d, JP–C = 60 Hz,
Cy (ipso-C)), 32.9 (d, 1JP–C = 53 Hz, CH2P), 26.8 (d, 2JP–C
=
3
12 Hz, Cy (o-C)), 26.3 (s, Cy (p-C)), 26.0 (d, JP–C = 8 Hz,
Cy (m-C)). 31P{1H} NMR δ: 10.2 (s). Anal. Calcd. for
C26H40NPTi: C 70.11, H 9.05, N 3.14; found: C 69.03, H
9.20, N 3.08. Yellow crystals suitable for X-ray diffraction
were grown by slow evaporation from pentanes.
Synthesis of p-C6H4(CH2PR2NTiCp′Me2)2 (Cp′ = Cp*,
Cp; R = t-Bu, Cy)
Compounds 17 (Cp′ = Cp*; R = t-Bu), 18 (Cp′ = Cp*; R =
Cy), 19 (Cp′ = Cp; R = t-Bu), and 20 (Cp′ = Cp; R = Cy)
were all prepared in a similar manner and one sample prepa-
ration is detailed. Compound 5 (0.21 g, 0.27 mmol) was
slurried in Et2O (25 mL), and a solution of MeMgBr in the
same solvent (1.4 mmol) was added dropwise via syringe at
25 °C. The heterogeneous solution was stirred for 15 h, after
which time the solvent was removed in vacuo. Extraction
with hexanes (3 × 10 mL) and filtration through Hyflo Super
Cel® afforded a colorless liquid. Removal of the solvent in
vacuo generated a white solid. The yield increased when ex-
traction was performed with toluene. Compound 17: Yield
1
0.23 g, 77%. H NMR: 7.50 (s, 4H, C6H4), 2.96 (d, 4H,
JP–H = 11 Hz, CH2), 2.12 (s, 30H, Cp*), 1.17 (d, 36H, JP–H
=
14 Hz, t-Bu), 0.46 (s, 12H, TiMe). 13C{1H} NMR: 133.4 (s,
C6H4), 130.8 (s, C6H4), 118.4 (s, Cp*), 44.4 (s, TiMe), 38.9
(d, JP–C = 54 Hz, t-Bu), 31.6 (d, JP–C = 48 Hz, CH2), 28.0 (s,
t-Bu), 12.3 (s, Cp*). 31P{1H} NMR: 22.0 (s). Anal. Calcd.
for C48H86N2P2Ti2: C 67.91, H 10.21, N 3.30; found: 67.51,
X-ray data collection and reduction
Crystals were manipulated and mounted in capillaries in a
glove box, 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 re-collecting 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 (Bruker AXS, Madison, Wis.).
An empirical absorption correction based on redundant data
was applied to each data set. Subsequent solution and refine-
ment was performed using the SHELXTL solution package
(Bruker AXS, Madison, Wis.).
H 9.96, N. 2.95. Compound 18: White solid. Yield 0.41 g,
1
73%. H NMR: 7.35 (s, 4H, C6H4), 2.92 (d, 4H, JP–H
=
13 Hz, CH2P), 2.10 (s, 30H, Cp*), 1.81–1.10 (m, 44H, Cy),
0.43 (s, 12H, TiMe). 13C{1H} NMR: 132.5 (s, C6H4), 130.5
(s, C6H4), 122.3 (s, Cp*), 42.7 (s, TiMe), 38.2 (d, JP–C
61 Hz, Cy), 34.0 (d, JP–C = 52 Hz, CH2P), 27.1 (d, JP–C
=
=
12 Hz, Cy), 26.5 (d, JP–C = 6 Hz, Cy), 26.4 (s, Cy), 11.9 (s,
Cp*). 31P{1H} NMR: 8.0 (s). Anal. Calcd. for
C54H94N2P2Ti2: C 69.81, H, 10.20, N 3.02; found: 69.56, H,
9.94, N 2.94. 19: Colorless block crystals. Yield 0.16 g,
1
83%. H NMR: 7.48 (s, 4H, C6H4), 6.18 (s, 10H, Cp), 2.80
(d, 4H, JP–H = 10 Hz, CH2P), 1.06 (d, 36H, JP–H = 14 Hz, t-
Bu), 0.72 (s, 12H, TiMe). 13C{1H} NMR: 132.5 (s, C6H4),
130.8 (s, C6H4), 110.9 (s, Cp), 41.3 (s, CH2P), 38.4 (d,
JP–C = 54 Hz, t-Bu), 31.7 (s, TiMe), 27.4 (s, t-Bu). 31P{1H}
NMR: 22.6 (s). Anal. Calcd. for C38H66N2P2Ti2: C 64.41, H
9.39, N 3.95; found: C 64.15, H 9.39, N 3.47. Crystals suit-
able for X-ray diffraction were grown by slow evaporation
from toluene. Compound 20: White solid. Yield 0.45 g,
77%. 1H NMR δ: 7.48 (s, 4H, C6H4), 6.22 (s, 10H, Cp), 2.70
(d, 4H, JP–H = 12 Hz, CH2P), 1.65–1.06 (m, 44H, Cy), 0.74
(s, 12H, TiMe). 13C{1H} NMR: 132.1 (s, C6H4), 130.6 (s,
C6H4), 110.8 (s, Cp), 40.8 (s, TiMe), 37.6 (d, JP–C = 60 Hz,
Structure solution and refinement
Non-hydrogen atomic scattering factors were taken from
the literature tabulations (42). 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
© 2004 NRC Canada

Hollink et al.
1313
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2
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insufficient data. In the latter cases, atoms were treated iso-
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drogens were allowed to ride on the carbon to which they
are bonded assuming 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 the hydrogens are
bonded. The H-atom contributions were calculated but not
refined. The locations of the largest peaks in the final differ-
ence Fourier map calculation as well as the magnitude of the
residual electron densities in each case were of no chemical
significance. Details are provided in Table 1 and the supple-
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Acknowledgements
Financial support from the Natural Sciences and Engi-
neering Research Council of Canada (NSERC) and NOVA
Chemicals Corporation is gratefully acknowledged. EH is
grateful for the award of an Ontario Graduate Scholarship.
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Supplementary data may be purchased form the Deposi-
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tional Research Council Canada, Ottawa, ON K1A OS2,
Canada (http://www.nrc.ca/cisti/irm/unpub_e.shtml for infor-
mation on obtaining electronically). CCDC 223337–223350
contain the supplementary crystallographic data for this paper.
These data can be obtained, free of charge, via www.ccdc.
cam.ac.uk/conts/retrieving.html (or from the Cambridge
Crystallographic Data Centre, 12 Union Road, Cambridge
CB2 1EZ, UK; fax: +44 1233 336033; or deposit@ccdc.
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© 2004 NRC Canada