Alkylphenyl-substituted bis(salicylaldiminato) titanium catalysts in ethene polymerization

Article abstract of DOI:10.1021/om0610391

Titanium complexes bearing anionic [N,O^_] bidentate salicylaldiminato ligands were synthesized with excellent yields via one- or two-step processes. The common feature of these catalyst precursors is the presence of aliphatic substituents (adamantyl, benzyl, (CH₂) ₂Ph, (CH₂)₃Ph, and i-Pr) at the aldimino moieties. X-ray structure analysis of the benzyl-substituted complex revealed a distorted octahedral geometry, wherein nitrogen and chlorine atoms form the basal plane while the oxygen atoms of the phenoxy moieties complete the coordination sphere of the Ti center by occupying the axial positions. However, according to dynamic ¹H NMR measurements, these complexes can possess different structural isomers in solution, even at room temperature. After MAO activation, the catalysts displayed a range of catalytic activities [3-1700 kg_PE/(mol_Ti·h·bar)]. The complex with ethylphenyl substituents was the most active in the series. In general, the (CH₂)₂Ph- and (CH₂)₃Ph-substituted catalysts produce PE with unimodal molar mass distribution, while the benzyl-, adamantyl-, and isopropyl-substituted catalysts tend to produce high molar mass bimodal PE with low activity. Computational methods were used to interpret the polymerization results, particularly the catalytic activity.

Full text of DOI:10.1021/om0610391

3690
Organometallics 2007, 26, 3690-3698
Alkylphenyl-Substituted Bis(salicylaldiminato) Titanium Catalysts in
Ethene Polymerization
Antti Pa¨rssinen,† Tommi Luhtanen,‡ Martti Klinga,† Tapani Pakkanen,‡
Markku Leskela¨,† and Timo Repo*,†
Department of Chemistry, Laboratory of Inorganic Chemistry, UniVersity of Helsinki, P.O. Box 55,
FIN-00014 Helsinki, Finland, and Department of Chemistry, UniVersity of Joensuu, P.O. Box 111,
FIN-80101 Joensuu, Finland
ReceiVed NoVember 10, 2006
Titanium complexes bearing anionic [N,O-] bidentate salicylaldiminato ligands were synthesized with
excellent yields via one- or two-step processes. The common feature of these catalyst precursors is the
presence of aliphatic substituents (adamantyl, benzyl, (CH2)2Ph, (CH2)3Ph, and i-Pr) at the aldimino
moieties. X-ray structure analysis of the benzyl-substituted complex revealed a distorted octahedral
geometry, wherein nitrogen and chlorine atoms form the basal plane while the oxygen atoms of the
phenoxy moieties complete the coordination sphere of the Ti center by occupying the axial positions.
However, according to dynamic 1H NMR measurements, these complexes can possess different structural
isomers in solution, even at room temperature. After MAO activation, the catalysts displayed a range of
catalytic activities [3-1700 kgPE/(molTi‚h‚bar)]. The complex with ethylphenyl substituents was the most
active in the series. In general, the (CH2)2Ph- and (CH2)3Ph-substituted catalysts produce PE with unimodal
molar mass distribution, while the benzyl-, adamantyl-, and isopropyl-substituted catalysts tend to produce
high molar mass bimodal PE with low activity. Computational methods were used to interpret the
polymerization results, particularly the catalytic activity.
of phenoxyimine ligands to the metal, the chlorides adopt a cis
orientation,5e,6 which is generally considered to be a prerequisite
for efficient polymerization catalysts. In this context Fujita et
al. developed novel ligand combinations for group 4 metals and
reported the most efficient homogeneous nonmetallocene cata-
lysts for ethene polymerization to date. In these highly active
Ti complexes, fluorinated aromatic substituents at the imine
nitrogen together with either a t-Bu or cumyl group at the
3-position adjacent to the phenoxy oxygen are the distinctive
features.6b,7
Introduction
Only a few catalyst classes have appeared1 that possess
catalytic activities to challenge zirconium-based metallocenes2
in the area of homogeneous catalysts for ethene polymerization.
The discovery of competitive late transition metal catalysts based
on iron as well as nickel and palladium complexes bearing
tridentate 2,6-bis-imino(pyridine) or bidentate diimine ligands,
respectively, initiated intensive research on this topic more than
a decade ago.3 Schiff base group 4 metal complexes have been
known since the 1960s,4 but during the last 10 years they have
attracted considerable attention as possible catalyst precursors
for olefin polymerization.5 Phenoxyimine ligands are especially
attractive, as they are easily prepared via a classical imine
condensation reaction between a suitable salicylaldehyde and
any primary amine. The modification possibilities for these
ligands are, therefore, plentiful. In addition, upon coordination
One of the phenoxy-imine catalysts studied, bearing bulky
3,5-dicumyl substituents and unsubstituted phenyl at the imine
nitrogen, had unusual behavior. First it produced multimodal
(4) (a) Bradley, D. C.; Hursthouse, M. B.; Rendall, I. F. J. Chem. Soc.,
Chem. Commun. 1969, 12, 672-673. (b) Prashar, P.; Tandon, J. P. J. Less
Common Met. 1967, 13, 541-547. (c) Gupta, S. R.; Tandon, J. P. Z.
Naturforsch., B: Chem. Sci. 1970, 25, 1231-1234. (d) Gilli, G.; Cruick-
shank, D. W. J.; Beddoes, R. L.; Mills, O. S. Acta Crystallogr., Sect. C:
Cryst. Struct. Commun. 1972, B28, 1889-1893. (e) Pasquali, M.; Marchetti,
F.; Landi, A.; Floriani, C. Dalton Trans. 1978, 6, 545-549. (f) Dell’Amico,
G.; Marchetti, F.; Floriani, C. Dalton Trans. 1982, 11, 2197-2202. (g)
Solari, E.; Corazza, F.; Floriani, C.; Chiesi-Villa, A.; Guasti, C. Dalton
Trans. 1990, 4, 1345-1355. (h) Repo, T.; Klinga, M.; Leskela¨, M.;
Pietika¨inen, P.; Brunow, G. Acta Crystallogr., Sect. C: Cryst. Struct.
Commun. 1996, C52, 2742-2745.
* Corresponding author. Fax: +358-9-19150198. E-mail: timo.repo@
helsinki.fi.
† University of Helsinki.
‡ University of Joensuu.
(1) (a) Gibson, V. C.; Spitzmesser, S. K. Chem. ReV. 2003, 103, 283-
315. (b) Britovsek, G. J. P.; Gibson, V. C.; Wass, D. F. Angew. Chem., Int.
Ed. 1999, 38, 428-447.
(2) (a) Janiak, C. In Metallocenes; Togni, A., Haltermann, R. L., Eds.;
Wiley-VCH: Weinheim, 1998; Vols. 1 and 2. (b) Busico, V.; Cipullo, R.
Prog. Polym. Sci. 2001, 26, 443-533. (c) Resconi, L.; Cavallo, L.; Fait,
A.; Piemontesi, F. Chem. ReV. 2000, 100, 1253-1345. (d) Brintzinger, H.
H.; Fischer, D.; Mu¨lhaupt, R.; Rieger, B.; Waymouth, R. M. Angew. Chem.,
Int. Ed. Engl. 1995, 34, 1143-1170.
(3) (a) Johnson, L. K.; Killian, C. M.; Brookhart, M. J. Am. Chem. Soc.
1995, 117, 6414-6415. (b) Johnson, L. K.; Mecking, S.; Brookhart, M. J.
Am. Chem. Soc. 1996, 118, 267-268. (c) Britovsek, G. J. P.; Gibson, V.
C.; Kimberley, B. S.; Maddox, P. J.; McTavish, S. J.; Solan, G. A.; White,
A. J. P.; Williams, D. J. Chem. Commun. 1998, 7, 849-850. (d) Small, B.
L.; Brookhart, M.; Bennett, A. M. A. J. Am. Chem. Soc. 1998, 120, 4049-
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Organometallics 1995, 14, 371-386. (b) Repo, T.; Klinga, M.; Pietika¨inen,
P.; Leskela¨, M.; Uusitalo, A.-M.; Pakkanen, T.; Hakala, K.; Aaltonen, P.;
Lo¨fgren, B. Macromolecules 1997, 30, 171-175. (c) Bei, X.; Swenson, D.
C.; Jordan, R. F. Organometallics 1997, 16, 3282-3302. (d) Kim, I.;
Nishihara, Y.; Jordan, R. F.; Rogers, R. D.; Rheingold, A. L.; Yap, G. P.
A. Organometallics 1997, 16, 3314-3323. (e) Matsui, S.; Tohi, Y.; Mitani,
M.; Saito, J.; Makio, H.; Tanaka, H.; Nitabaru, M.; Nakano, T.; Fujita, T.
Chem. Lett. 1999, 1065-1066. (f) Segal, S.; Goldberg, I.; Kol, M.
Organometallics 2005, 24, 200-202.
(6) See for example: (a) Fro¨hlich, R.; Saarenketo, P.; Strauch, J.; Warren,
T. H.; Erker, G. Inorg. Chim. Acta 2000, 300-302, 810-821. (b)
Matsukawa, N.; Matsui, S.; Mitani, M.; Saito, J.; Tsuru, K.; Kashiwa, N.;
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10.1021/om0610391 CCC: $37.00 © 2007 American Chemical Society
Publication on Web 06/14/2007

Bis(salicylaldiminato) Titanium Catalysts
Organometallics, Vol. 26, No. 15, 2007 3691
Scheme 1. Schematic Representation of Ligand Precursors
PE, and second the ratios of the different molar mass fractions
and polymerization activities alternated with reaction temper-
ature.8 A similar phenomenon was observed in our studies
concerning bis(phenoxyanilinato)titanium catalysts, where the
production of multimodal PE was frequent.9 Molecular modeling
of these bis(phenoxyanilinato)titanium catalysts revealed inter-
esting results, which correlate well with the experimental
polymerization data. According to ab initio calculations, the
relative stabilization energies of the structural isomers of these
complexes can change after activation. Therefore, the cationic
complex formed does not necessarily have to adopt the same
orientation with the salicylaldiminato ligands as that of the initial
dichloro complex.9 Such fluxional behavior is well known also
for neutral titanium dichloro complexes and is dependent on
the ligand substitution pattern.8
The observed multimodal polymerization behavior for bis-
(phenoxyanilinato)titanium catalysts may be due to changes in
the orientation of the salicylaldiminato ligands, leading to
simultaneous polymerization with different structural isomers.
Furthermore, according to calculations, a common feature of
the most active (phenoxyanilinato)titanium catalyst precursors
was their tendency to change their coordination sphere by
moving the imine nitrogens from cis to trans positions upon
activation.9 To gain further understanding of these fluxional
catalysts, we extended our studies toward alkylphenyl (Ph(CH2)n,
n ) 1, 2, and 3) substituted titanium complexes, which also
tend to change the orientation of their imino nitrogens from cis
to trans upon activation. In addition, the polymerization behavior
of these alkylphenyl-substituted titanium complexes was com-
pared with alkyl-substituted complexes bearing rather small
(isopropyl) as well as sterically bulky (adamantyl) imino
substituents.
1-7
L2Ti(NMe2)2 and the resulting dichloro derivatives were formed
with practically quantitative yields. The amido complexes
1
possessed sharp singlet resonances in the H NMR (CDCl3)
spectra for the imino protons, indicating the presence of the
C2-symmetric cis or trans isomer, solely. When converted to
their dichloro analogues, 1-Ti and 2-Ti according to the
calculations and crystallographic data obtain the cis-configu-
1
ration,11 while for 3-Ti, the H NMR spectra revealed three
singlets with the intensity ratio 1:4:1, indicating a mixture of
cis (singlet) and cis,cis (two singlets) isomers (2:1). After
purification of the complex at slightly higher temperatures, the
intensity ratio of cis and cis,cis isomers changed to 5:1 (NMR
measured at room temperature), indicating different temperature-
dependent stabilities for the isomers.
To gain a more detailed understanding of the fluxional
1
behavior of 3-Ti, dynamic H NMR (C6D5Br) measurements
were carried out. For these studies 3-Ti was isolated and purified
separately at low temperatures to increase the yield of the cis,-
cis isomer, the ratio now being 1:2 for cis and cis,cis isomers.
In the spectrum of 3-Ti at room temperature there are three
equal size resonances arising from CHdN ligand protons
together with an aromatic signal in the same region (7.65 ppm)
(Figure 1). The imine proton signals at 7.81 and 7.66 ppm can
be assigned to the cis,cis configuration (C1-symmetry), while
the third imino signal at 7.73 ppm can be assigned to the cis
configuration (C2-symmetry). When the temperature increases,
the signals due to the cis,cis imino protons shift closer to the
signal at 7.73 ppm (C2-symmetric complex), but the coalescence
point was not reached up to 75 °C, which was the highest
possible temperature for these measurements. However, in the
purification process the temperature of the solution was always
increased above 80 °C, leading to a higher yield of the cis isomer
at the expense of the cis,cis isomer. Although the coalescence
point was not reached in these measurements, it is clear that at
high temperatures there is a chance for the cis,cis isomer to be
converted to the cis isomer.
Results and Discussion
Ligands and Complexes. Imine ligands 1-7 were prepared
via a classical condensation reaction between aldehydes and
amines (Scheme 1). As reported previously,9 amines can be
efficiently converted to salicylaldimines by simple mixing of
salicylaldehyde and the corresponding aliphatic amine and
heating overnight at 110 °C in the absence of solvent. Crude
products from the syntheses were isolated with high yields as
1
bright yellow powders, and according to H NMR spectra, all
of these salicylaldimines were pure as such.
Titanium dichloro complexes (1-Ti, 2-Ti, and 3-Ti) (Scheme
2) were synthesized via direct metalation of the ligand precursors
1-3 with Ti(NMe2)4, followed by replacement of the amido
groups with chlorines using excess Me3SiCl.9,10 The intermediate
The titanium complexes bearing ligands 4, 5, and 7, i.e., those
without the tert-butyl substituent next to the phenol group, were
most efficiently synthesized via silylation of the ligand precur-
sors using 1,1,1,3,3,3-hexamethyldisilazane followed by reaction
with TiCl4. This method gave nearly quantitative yields of the
desired titanium complexes 4-Ti, 5-Ti, and 7-Ti (Scheme 2).9,12
These titanium complexes can also be prepared simply by the
(7) (a) Matsui, S.; Mitani, M.; Saito, J.; Tohi, Y.; Makio, H.; Matsukawa,
N.; Takagi, Y.; Tsuru, K.; Nitabaru, M.; Nakano, T.; Tanaka, H.; Kashiwa,
N.; Fujita, T. J. Am. Chem. Soc. 2001, 123, 6847-6856. (b) Tian, J.; Hustad,
P. D.; Coates, G. W. J. Am. Chem. Soc. 2001, 123, 5134-5135. (c) Saito,
J.; Mitani, M.; Mohri, J.-I.; Ishii, S.-I.; Yoshida, Y.; Matsugi, T.; Kojoh,
S.-I.; Kashiwa, N.; Fujita, T. Chem. Lett. 2001, 576-577. (d) Saito, J.;
Mitani, M.; Mohri, J.-I.; Yoshida, Y.; Matsui, S.; Ishii, S.-I.; Kojoh, S.-I.;
Kashiwa, N.; Fujita, T. Angew. Chem., Int. Ed. 2001, 40, 2918-2920. (e)
Mitani, M.; Mohri, J.-i.; Furuyama, R.; Ishii, S.; Fujita, T. Chem. Lett. 2003,
32, 238-239. (f) Mitani, M.; Mohri, J.-i.; Yoshida, Y.; Saito, J.; Ishii, S.;
Tsuru, K.; Matsui, S.; Furuyama, R.; Nakano, T.; Tanaka, H.; Kojoh, S.-i.;
Matsugi, T.; Kashiwa, N.; Fujita, T. J. Am. Chem. Soc. 2002, 124, 3327-
3336. (g) Mitani, M.; Saito, J.; Ishii, S.-I.; Nakayama, Y.; Makio H.;
Matsukawa N.; Matsui S.; Mohri, J.-I.; Furuyama, R.; Terao, H.; Bando,
H.; Tanaka, H.; Fujita, T. Chem. Rec. 2004, 4, 137-58.
(10) (a) McKnight, A. L.; Masood, M. A.; Waymouth, R. M. Organo-
metallics 1997, 16, 2879-2885. (b) Westmoreland, I.; Munslow, I.;
O’Shaughnessy, P.; Scott, P. Organometallics 2003, 22, 2972-2976.
(11) NOE measurements were carried out with complex 1-Ti to find
out whether the singlet imine resonance is arising from the cis or trans
isomer. In both isomers there is a NOE effect between the benzyl CH2
group and the phenoxy tert-butyl group. According to the modeling, in the
cis isomer the distance for the NOE is shorter (∼2.5 Å) than for the trans
isomer (∼3.2 Å). The NOE effect with two mixing time (300 and 500 ms)
values gave a distance close to 2.4 Å, which supports the cis configuration.
(8) (a) Tohi, Y.; Makio, H.; Matsui, S.; Onda, M.; Fujita, T. Macro-
molecules 2003, 36, 523-525. (b) Makio, H.; Fujita, T. Macromol. Symp.
2004, 213, 221-233.
(9) Pa¨rssinen, A.; Luhtanen, T.; Klinga, M.; Pakkanen, T.; Leskela¨, M.;
Repo, T. Eur. J. Inorg. Chem. 2005, 11, 2100-2109.

3692 Organometallics, Vol. 26, No. 15, 2007
Scheme 2. Schematic Representation of the Catalyst Precursors Studied Hereina
Pa¨rssinen et al.
a
Complexes having nitrogens in a cis configuration (1-Ti-4-Ti) and complexes having a trans configuration (5-Ti-7-Ti) according to HF
calculations (Table 3) are shown.
Table 1. Crystallographic Data for Complex 1-Ti
chemical formula
fw
space group
a, Å
b, Å
c, Å
C36H40Cl2N2O2Ti
651.50
P21/c
10.238(2)
13.299(1)
24.412(4)
90
90.371(8)
90
3323.8(9)
1.302
R, deg
â, deg
γ, deg
V, Å3
d
calc, g cm-3
Z
4
µ, mm-1
λ, Å
T, K
Ra
0.452
0.71073
173(2)
0.0544
0.1012
Figure 1. 1H NMR spectrum of complex 3-Ti shown at ambient
and higher temperatures.
b
Rw
a R ) ∑||Fo| - |Fc||/∑|Fo| for observed reflections [I > 2σ(I)]. b Rw
)
2
2
2
{∑[w(Fo - Fc )]/∑[w(Fo )2]}1/2 for all data.
Table 2. Selected Structural Parameters for Complex 1-Ti
bond lengths, Å (exptl) bond angles, deg (exptl)
Ti-Cl1
2.311(1)
2.303(1)
2.187(2)
2.247(2)
1.873(2)
1.850(2)
1.499(3)
1.339(3)
1.348(3)
1.299(4)
1.489(4)
1.296(3)
O-Ti-O
168.48(7)
81.37(8)
88.06(8)
92.35(8)
82.01(8)
91.25(5)
93.20(6)
89.96(6)
171.80(6)
84.38(7)
89.42(5)
170.97(6)
96.85(3)
Ti-Cl2
Ti-N1
O2-Ti-N2
O1-Ti-N2
O2-Ti-N1
O1-Ti-N1
O1-Ti-Cl1
O2-Ti-Cl1
N1-Ti-Cl2
N2-Ti-Cl2
N-Ti-N
Ti-N2
Ti-O1
Ti-O2
N2-C32
O1-C1
O2-C21
N1-C11
N1-C12
N2-C31
N2-Ti-Cl1
N1-Ti-Cl1
Cl-Ti-Cl
Figure 2. ORTEP plot of 1-Ti with thermal ellipsoids drawn at
the 50% probability level. All hydrogen atoms are removed for
clarity.
and angles resemble the ones earlier reported for bis[N-(3-tert-
butylsalicylidene)-2,3,4,5,6-pentafluoroanilinato]titanium(IV)
dichloride.7g
combination of 2 molar equiv of the neutral salicylaldimines
with titanium tetrachloride. This method was especially ap-
plicable for the most sterically bulky ligand 6, and the complex
6-Ti was quantitatively formed (Scheme 2). The solubility of
complexes 4-Ti-7-Ti in common deuterated solvents was very
poor, and as a result 13C spectra with satisfactory resolution
could not be obtained.
Correlation between Complex Structure and Polymeri-
zation Behavior. There are five different possible coordination
geometries for bis(salicylaldiminato)titanium dichloride com-
plexes, three of which have chlorides in cis positions and are
therefore considered as suitable catalyst precursors for olefin
polymerization.5e,6b In the first of these catalytically active
conformations, the imine nitrogens are in cis positions, while
the oxygens have trans orientations (Scheme 3, cis). In another
conformation both the nitrogens and the oxygens have cis
orientations (Scheme 3, cis,cis), while in the third the nitrogens
occupy trans positions and the oxygens occupy cis positions
(Scheme 3, trans). All of these isomers have been previously
observed in X-ray studies for (phenoxyimino)2TiCl2 com-
plexes.6,13 The remaining two geometries are related to com-
plexes having a large Cl-Ti-Cl angle (close to 180°) and are
Red crystals of complex 1-Ti suitable for X-ray determination
were grown at room temperature from a saturated toluene
solution (Figure 2). The X-ray data showed that the titanium
center is located in the plane of the N2Cl2 core, and the trans
orientation of the phenoxy oxygens with the O-Ti-O bond
angle of 168.48° (Table 1 and Table 2) leads to a distorted
octahedral coordination. The chlorides have a cis orientation
with a Cl-Ti-Cl bond angle of 96.85° and almost equivalent
bond lengths (2.30 and 2.31 Å). In general, the bond distances
(12) Anwander, R.; Eppinger, J.; Nagl, I.; Scherer, W.; Tafipolsky, M.;
Sirsch, P. Inorg. Chem. 2000, 39, 4713-4720.
(13) Cherian, A. E.; Lobkovsky, E. B.; Coates G. W. Macromolecules
2005, 38, 6259-6268.

Bis(salicylaldiminato) Titanium Catalysts
Organometallics, Vol. 26, No. 15, 2007 3693
Scheme 3. Schematic Representation of Different
Coordination Geometries for Octahedral Dichloro
Complexes Having Chlorides in cis Forma
Scheme 4. Schematic Representation of the Activation
Procedure of the Bis(salicylaldiminato) Titanium Dichloride
Complex Starting from a cis Orientation and Ending with
the Cationic Complex with a trans Orientation (1-Ti-3-Ti)
In the cis isomer the imino nitrogens are in a cis while the phenoxy
oxygens are in a trans configuration. In cis,cis both the nitrogens and
the oxygens have a cis orientation, and in the trans isomer the nitrogens
are in a trans while the oxygens are in a cis configuration.
coordination geometries as predicted by ab initio calculations:
complexes 1-Ti-4-Ti have cis while complexes 5-Ti, 6-Ti, and
7-Ti have trans configurations.
Table 3. Relative Stabilization Energies (ERel) in kJ/mol of
the Dichloro Complexes (1-Ti-7-Ti), ERel(Cl2), and Their
Cationic Forms, ERel(Ti+Me), Including Different Isomeric
Structuresa
Observations in previous work have shown that knowledge
of the geometry of the dichloro complex for aryl-substituted
bis(salicylaldiminato)titanium catalysts does not necessarily
allow ethene polymerization behavior for the corresponding
catalysts to be reliably predicted.9 According to these studies,
the relative stabilization energies of the different isomers are
changed markedly when the complexes are activated. This may
lead to a change in the stability order for the isomers. The
alkylphenyl-substituted catalyst precursors (1-3)-Ti have a
tendency to change their coordination sphere by moving the
imine nitrogens from the cis to the trans position upon activation
(Scheme 4), as was the case for the most active bis(phenoxya-
nilinato)titanium catalysts.9 Since the geometry of the neutral
complexes has a tendency to change upon MAO activation, the
structure of the cationic species is required before any detailed
structure-polymerization correlations can be made.
The benzyl group as a substituent at the imine nitrogen is
interesting, as it is capable of rotation and therefore can provide
substantial steric shielding.14 However, as shown with unbridged
metallocene catalysts, benzyl substitution can retard the catalytic
activity via coordination from the ortho-carbon of the phenyl
ring to the cationic metal center.15 The solid-state structure of
1-Ti shows that the benzyl substituents point outward from the
titanium center as a result of the cis geometry (Figure 2).
According to calculations, the trans geometry is very close in
energy to cis geometry (Table 3) and structural transformation
from cis to trans brings the benzyl substituents into the vicinity
of the titanium center, as shown in Figure 3. When activated,
the trans conformer is the most stable and it gives the benzyl
groups an opportunity to interact with the catalytically active,
cationic metal center (Table 3). As a consequence, MAO-
activated 1-Ti revealed low activities in ethene polymerizations,
giving a maximum of 40 kgPE/(molTi‚h‚bar) at 80 °C (Table 4).
In 3 bar ethene pressure two separable molar mass areas
appeared in the GPC chromatograph, the lower of which
decreases with increasing monomer concentration. We assume
that this particular phenomenon is linked to the benzyl substit-
complex
E
Rel(Cl2)
ERel(Ti+Me)
1-Ti_cis
-4
-1
0
-3
2
0
-1
4
0
-17
-49
0
-22
-45
0
1-Ti_cis,cis
1-Ti_trans
2-Ti_cis
2-Ti_cis,cis
2-Ti_trans
3-Ti_cis
3-Ti_cis,cis
3-Ti_trans
4-Ti_cis
4-Ti_cis,cis
4-Ti_trans
5-Ti_cis
5-Ti_cis,cis
5-Ti_trans
6-Ti_cis
6-Ti_cis,cis
6-Ti_trans
7-Ti_cis
7
0
-16
-2
21
0
17
39
0
8
9
0
3
0
47
2
0
82
0
-5
2
0
0
7-Ti_cis,cis
7-Ti_trans
14
0
61
0
a The most stable isomer has been marked. In calculations the trans
isomer of each catalyst precursor has been chosen as a point of reference.
See Scheme 3 for the definition of different coordination geometries.
known for complexes bearing salen-type Schiff base ligands.4,5b
The presence of this large Cl-Ti-Cl angle is apparently
accountable for the low activities of catalysts with these
geometries in R-olefin polymerization, and hence they have been
omitted from the ab initio calculations.
Geometry prediction of aryl-substituted phenoxyimino com-
plexes using HF calculations has been successfully utilized in
earlier studies.9 Similar stabilization energy values for the
different isomers can be obtained using DFT; however the
structures calculated using HF are finalized faster. HF calcula-
tions are important for resolution of the geometries of the
complexes synthesized herein, as only one of them (complex
1-Ti) could be determined by single-crystal X-ray measure-
ments. The geometry of the X-ray crystal structure obtained
for complex 1-Ti is in good agreement with the HF-calculated
one (Table 3). It can be seen from the calculated data that the
stabilization energies of the three different isomers of complex
1-Ti are quite close to each other (Table 3), the cis configuration
being only 3 kJ/mol more stable than the corresponding cis,cis
geometry. In the case of complex 3-Ti, which possesses more
than one geometry in solution, the calculated energy difference
between the cis and trans isomers was only 1 kJ/mol. The
structures of the titanium dichloro complexes studied herein (1-
Ti-7-Ti) can be divided into two groups according to their
(14) Lorber, C.; Donnadieu, B.; Choukroun, R. Organometallics 2000,
19, 1963-1966.
(15) (a) Bu¨hl, M.; Sassmannshausen, J. J. Chem. Soc., Dalton Trans.
2001, 1, 79-84. (b) Bochmann, M.; Green, M. L. H.; Powell, A. K.;
Sassmannshausen, J.; Triller, M. U.; Wocadlo, S. J. Chem. Soc., Dalton
Trans. 1999, 43-49. (c) Doerrer, L.; Green, M. L. H.; Hau¨ssinger, D.;
Sassmannshausen, J. Dalton Trans. 1999, 2111-2118. (d) Aitola, E.;
Surakka, M.; Repo, T.; Linnolahti, M.; Lappalainen, K.; Kervinen, K.;
Klinga, M.; Pakkanen, T.; Leskela¨, M. J. Organomet. Chem. 2005, 690,
773-783. (e) Jany, G.; Gustafsson, M.; Repo, T.; Aitola, E.; Dobado, J.
A.; Klinga, M.; Leskela¨, M. J. Organomet. Chem. 1998, 553, 173-178. (f)
Lorber, C.; Donnadieu, B.; Choukroun, R. Organometallics 2000, 19, 1963-
1966.

3694 Organometallics, Vol. 26, No. 15, 2007
Pa¨rssinen et al.
Figure 3. Cis (left) and trans (right) geometries of complex 1-Ti calculated by the HF-method at the 3-21G* level.
Table 4. Selected Ethene Polymerization Results with Catalysts (1-Ti-7-Ti) after MAO Activationa
run
complex
cat. (µmol)
m (g)
Tp (°C)b
p (bar)c
activityd
M
w (kg/mol)
Mw/Mn
T
m (°C)e
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
1-Ti
1-Ti
1-Ti
1-Ti
1-Ti
2-Ti
2-Ti
2-Ti
2-Ti
2-Ti
3-Ti
3-Ti
3-Ti
3-Ti
3-Ti
4-Ti
5-Ti
6-Ti
7-Ti
7-Ti
7-Ti
7-Ti
7-Ti
10
10
10
10
10
5
5
5
5
2.5
5
5
5
5
5
20
10
10
10
10
10
10
10
0.03
0.16
0.155
1.58
0.45
5.58
5.81
9.52
10.33
7.25
4.94
4.51
7.39
1.87
7.05
1.28
5.03
1.09
0.06
0.08
0.11
0.30
0.38
60
40
60
80
60
60
40
60
80
60
60
40
60
80
60
60
60
60
60
40
60
80
60
3
5
5
5
10
3
5
5
5
10
3
5
5
5
10
5
5
5
3
5
1
4
4
40
6
1120
700
1140
1240
1740
990
540
890
220
850
20
600/8
45
740/10
230/4
790/6
520
580
435
375
220
160
160
95
120
140
400
710
950
2.1/1.7
1.8
2.2/1.4
1.9/2.0
2.0/2.4
2.1
2.2
2.2
1.9
2.0
135
135
137
139
135
136
137
136
136
136
137
138
136
135
134
137
135
140
141
143
140
138
143
2.1
2.1
2.8
2.1
2.0
21.8
20.9
3.5
4.3
4.7
3.3
3.5
3.4
130
30
3
2
3
605
630
560
1130
720
5
5
10
8
5
a Polymerization conditions: [Al]/[Ti] ) 2000, 200 mL of toluene, polymerization times 2-Ti and 3-Ti, 20 min; runs 10 and 15, 10 min; and 1-Ti and
4-Ti-7-Ti, 45 min. b Polymerization temperature. c Monomer pressure. d Activity in (kg PE)/(mol‚[Ti]‚h‚bar). e Onset melting temperatures of the polyethenes
after heating the samples to 230 °C and cooling again to 30 °C (cooling and heating rate 20 °C/min).
uents, which tend to block the active site at lower pressures. At
higher ethene concentrations this trend fades away.
activity. Average activities recorded for 3-Ti/MAO bearing
propylphenyl imino substituents were in the range 220-1100
kgPE/(molTi‚h‚bar) and were dependent on the polymerization
temperature. This catalyst also produced unimodal PE with
narrow polydispersities, as is typical for single-center catalysts.
A series of alkyl-substituted complexes bearing either steri-
cally bulky adamantyl or small isopropyl groups at the imine
fragment were studied in order to illustrate the effect of alkyl
phenyl substitution on the activity of the catalysts 2-Ti and 3-Ti.
The adamantyl group was chosen to investigate whether bulky
alkyl substituents have a major effect on the activity of these
catalysts. Unlike the alkylphenyl-substituted complexes, 6-Ti
(adamantyl substituents) favors the trans geometry for the
dichloro complex, while the cis geometry is preferred for its
methyl cation (Table 2). In ethene polymerizations 6-Ti/MAO
showed low activities (below 10 kgPE/(molTi‚h‚bar) in conjunc-
tion with broad molar mass distribution (MMD) values (3.4-
4.7), indicating the multicenter behavior of the catalyst (Table
The catalyst 2-Ti/MAO possesses an ethyl group that acts as
a link between the phenyl group and the imine nitrogen. As
shown in Figure 4, the energetically favored anti-staggered ethyl
spacers force the phenyl rings away from the cationic metal
center, thus reducing the possibility for metal-phenyl interac-
tions. This small change in the ligand structure has a dramatic
influence on catalytic activity. Activities as high as 1700 kgPE/
(molTi‚h‚bar) were observed, and the polymerization properties
of the catalyst resemble those typical of single-center catalysts,
e.g., metallocenes. The polydispersity values were around 2,
and the molar mass obtained varied between 200 and 600 kg/
mol. Catalytic activities were increased at elevated temperatures
and pressures. A small decrease in molar mass was observed
when the temperature was raised from 40 to 80 °C (Table 4).
Further lengthening of the spacer between the imino nitrogen
and the phenyl ring has a slightly deteriorating effect on catalytic

Bis(salicylaldiminato) Titanium Catalysts
Organometallics, Vol. 26, No. 15, 2007 3695
series (below 130 kgPE/(molTi‚h‚bar) and produced clearly
bimodal PE. The isopropyl group, as a model for small alkyl
substituents at the imine nitrogen, was also studied. This
catalyst 7-Ti showed low activities (less than 30 kgPE/(molTi‚
h‚bar)) and produced multimodal MMD at all polymerization
conditions. Polymerization activities for (1-7)-Ti as a function
of temperature and monomer pressure are summarized in
Figure 5.
Conclusions
Upon activation with MAO, the alkyl-substituted bis(salicy-
laldiminato) catalysts 1-Ti-7-Ti displayed a range of catalytic
activities [3-1700 kgPE/(molTi‚h‚bar)] in ethene polymerization.
The polymerization results strongly suggest that alkyl substitu-
tion at the imino nitrogen atoms has an essential role in
determining the catalytic properties. The most active catalysts
were 2-Ti and 3-Ti, both of which contain alkylphenyl substit-
uents. When activated, these bis(salicylaldiminato)TiCl2 com-
plexes tend to change the relative coordination of the phenox-
yimine ligands from cis to trans, as seen previously with
moderately active phenyl-substituted bis(salicylaldiminato) cata-
lysts.9 Even though there is no unambiguous explanation for
the observed structure-activity relationship, the trans config-
uration of imine nitrogens leads to an arrangement of imine
substituents that provides improved steric protection for the
cationic metal center, which in turn might lead to increased
activities. Although the cation of 7-Ti may adopt the trans
configuration, the presence of sterically small imine substituents
increases the likelihood of side-reactions16 detrimental for
catalytic activities. According to HF calculations, catalysts
bearing sterically bulky adamantyl substituents (4-Ti, 5-Ti, and
6-Ti) do not undergo the cis-to-trans transformation, which was
observed with the alkylphenyl-substituted catalysts 1-Ti-3-Ti.
These may be the reasons for the observed lower activities of
4-Ti-7-Ti. The alkylphenyl substituents introduced here appear
to possess both the geometry and steric properties that lead to
highly active and thermally stable alkyl-substituted bis(salicy-
laldiminato) catalysts.
Figure 4. Calculated structure of the trans isomer of complex 2-Ti.
The most favorable conformer of the staggered ethyl linker forces
the phenyl rings away from the metal center, thus reducing possible
metal-phenyl interactions and increasing the steric protection of
the cationic metal center.
Experimental Section
General Comments. All organometallic syntheses were per-
formed under argon atmosphere using Schlenk techniques. Toluene
(HPLC grade) was dried and purified by refluxing over sodium
and benzophenone followed by distillation under an argon atmo-
sphere. Dichloromethane (CH2Cl2) was dried and purified over
CaH2 by refluxing for 4 h followed by distillation. Toluene was
stored over sodium flakes under an argon atmosphere. Salicylal-
dehyde (Fluka), 3-fluorosalicylaldehyde (Aldrich), 3-tertbutylsali-
cylaldehyde (Aldrich), benzylamine (Aldrich), 2-phenylethylamine
(Aldrich), 3-phenyl-1-propylamine (Aldrich), adamantylamine (Al-
drich), 1,1,1,3,3,3-hexamethyldisilazane (Aldrich), tetrakis(dim-
ethylamino)titanium (Aldrich), and TiCl4 (Riedel-de Hae¨n) were
used as received, methylaluminoxane (MAO, 30 wt % solution in
toluene) was purchased from Borealis Polymers Oy (Finland).
1H and 13C NMR spectra were collected on a Varian Gemini
2000 (200 MHz). Chemical shifts were referenced with respect to
CHCl3. EI mass spectra were acquired using a JEOL-SX102
instrument. DSC measurements (melting point) were performed
Figure 5. (a) Activities of the catalysts (1-Ti-7-Ti)/MAO at
different temperatures in ethene polymerization at 5 bar. (b)
Activities of the catalysts (1-Ti-7-Ti)/MAO at different pressures
in ethene polymerization at 60 °C.
4). To reduce the steric hindrance around the catalytic metal
center, the tert-butyl group at the 3-position of the phenoxy
group was replaced by an electron-withdrawing fluorine sub-
stituent. As a result of this change 5-Ti favors the trans
geometry, both in the dichloro as well as in the cationic form.
However, the average polymerization activities are only slightly
improved, being below 40 kgPE/(molTi‚h‚bar) at all polymeri-
zation conditions. The catalyst 4-Ti, without a substituent at
the 3-position, gave the highest activities in the adamantyl
(16) Possible side-reactions of the activated species in polymerization
conditions are extensively studied for metallocene catalysts. (a) Ziegler
Catalysts; Fink, G., Mu¨lhaupt, R., Brintzinger, H.-H., Eds.; Springer-
Verlag: Berlin, 1995. (b) Bryliakov, K. P.; Kravtsov, E. A.; Pennington,
D. A.; Lancaster, S. J.; Bochmann, M.; Brintzinger, H.-H.; Talsi, E. P.
Organometallics 2005, 24, 5660-5664. For reviews see refs 2b-d.

3696 Organometallics, Vol. 26, No. 15, 2007
Pa¨rssinen et al.
using a Perkin-Elmer DSC-2, calibrated with indium (temperature
scanning 20 °C/min). The scan area was from 25 to 232 °C. Mass
average molar mass (Mw), number average molar mass (Mn), and
molar mass distribution (MMD, Mw/Mn) of the polyethylene samples
were determined by GPC (Waters Alliance GPCV 2000, high-
temperature gel chromatographic device). The GPC had HMW7,
2*HMWGE, and HMW2 Waters Styrogel columns. Measurements
were carried out in 1,2,4-trichlorobenzene (TCB) at 160 °C relative
to polyethylene (PE) standards. 2,6-Di-tert-butyl-4-methylphenol
was used as a stabilizer.
g, 7.138 mmol) and 1-adamantylamine (1.08 g, 7.138 mmol) were
mixed to obtain 5 (1.85 g, 95%). Anal. Calcd for C17H20FNO: C,
1
74.70; H, 7.37; N, 5.12. Found: C, 74.88; H, 7.79; N, 4.89. H
NMR (200 MHz, CDCl3, 29 °C): δ 15.17 (s, OH), 8.26 (s, CNH),
7.24-6.59 (H-Ar), 2.20 (w, 3H, CH), 1.89 (w, 6H, CH2), 1.76 (w,
6H, CH2). 13C{1H} NMR (50.3 MHz, CDCl3, 29 °C): δC 159.21
(CF), 137.75 (Ar), 129.24 (Ar), 128.43 (Ar), 126.78 (Ar), 126.71
(Ar), 118.62 (Ar), 118.27 (Ar), 118.27 (Ar), 115.78 (Ar), 115.65
(Ar), 57.14 (CN), 42.98 (CH2), 36.31 (CH), 29.46 (CH). MS(EI)
m/z: 273 with appropriate isotope ratio for C17H20FNO+.
Synthesis of Compounds 1-7. Benzyl-N-(3-tert-butylsalicy-
laldimine) (1). tert-Butylsalicylaldehyde (2.5 mL, 0.0146 mol) and
benzylamine (1.59 mL, 0.0146 mol) were mixed in a 100 mL round-
bottom flask. The reaction mixture was heated to 120 °C and stirred
over night. The crude product (yellow powder) was recrystallized
from propanol (3.82 g, 98%). Anal. Calcd for C18H21NO: C, 80.86;
Adamantyl-N-(3-tert-butylsalicylaldimine) (6) was prepared by
a similar method to that described for 1. 3-tert-Butylsalicylaldehyde
(2.5 mL, 0.0146 mol) and 1-adamantylamine (2.21 g, 0.0146 mol)
were mixed to obtain 6 (4.54 g, 100%). Anal. Calcd for C21H29-
NO: C, 80.98; H, 9.38; N, 4.50. Found: C, 80.62; H, 9.83; N,
1
4.27. H NMR (200 MHz, CDCl3, 29 °C): δ 14.85 (s, OH), 8.35
1
H, 7.92; N, 5.24. Found: C, 81.00; H, 7.02; N, 5.09. H NMR
(s, NCH), 7.29, 7.24 (d, 1H, H-Ar), 7.13, 7.10 (d, 1H, H-Ar), 6.79
(t, 2H, H-Ar), 2.20 (w, 3H, CH), 1.89 (w, 6H, CH2), 1.76 (w, 6H,
CH2), 1.46 (s, 9H, CH3). 13C{1H} NMR (50.3 MHz, CDCl3,
29 °C): δC 161.66 (COH), 160.09 (CNH), 137.75 (Ar), 129.88
(Ar), 129.12 (Ar), 118.97 (Ar), 117.42 (Ar), 57.20 (CN), 43.25
(CH2), 36.59 (CH2), 35.03 (CH), 29.65 (CH3), 29.58 (CH). MS-
(EI) m/z: 311 with appropriate isotope ratio for C21H29NO+.
N-Isopropylsalicylaldimine (7) was prepared according to the
literature procedure.18
(200 MHz, CDCl3, 29 °C): δH 13.96 (s, OH), 8.46 (s, CNH), 7.42-
7.13 (m, 7H, H-Ar), 7.17, 7.13 (d, 1H, H-Ar), 6.83 (t, 1H, H-Ar),
4.81 (2H, CH2), 1.44 (s, 9H, CH3). 13C{1H} NMR (50.3 MHz,
CDCl3, 29 °C): δC 166.47 (CNH), 160.61 (COH), 138.44 (Ar),
137.62 (Ar), 129.99 (Ar), 129.69 (Ar), 128.84 (Ar), 128.09 (Ar),
127.52 (Ar), 118.89 (Ar), 118.05 (Ar), 63.38 (CH2), 35.04 (CH),
29.55 (CH3). MS(EI) m/z: 267 with appropriate isotope ratio for
C14H13NO+.
2-Phenylethyl-N-(3-tert-butylsalicylaldimine) (2) was prepared
by a similar method to that described for 1. tert-Butylsalicylaldehyde
(2.5 mL, 0.0146 mol) and 2-phenylethylamine (1.84 mL, 0.0146
mol) were used to obtain 2 (4.02 g, 98%). Anal. Calcd for C19H23-
NO: C, 81.10; H, 8.24; N, 4.98. Found: C, 80.18; H, 8.44; N,
4.76. 1H NMR (200 MHz, CDCl3, 29 °C): δH 14.08 (s, OH), 8.26
(s, CNH), 7.38-7.22 (m, 6H, H-Ar), 7.09, 7.05 (d, 1H, H-Ar), 6.80
(t, 1H, H-Ar), 3.84 (t, 2H, NCH2), 3.04 (t, 2H, Ar-CH2), 1.46 (s,
9H, CH3). 13C{1H} NMR (50.3 MHz, CDCl3, 29 °C): δC 165.98
(CNH), 160.71 (COH), 139.52 (Ar), 137.58 (Ar), 129.76 (Ar),
129.47 (Ar), 129.09 (Ar), 128.69 (Ar), 126.54 (Ar), 118.80 (Ar),
117.88 (Ar), 61.18 (NCH2), 37.73 (CMe3) 35.04 (Ar-CH2), 29.55
(CH3). MS(EI) m/z: 281 with appropriate isotope ratio for C15H15-
NO+.
Synthesis of Complexes (1-7)-Ti. Bis(κN,κO-N-benzyl-3-tert-
butylsalicylaldiminato)TiCl2 (1-Ti). A precooled (-78 °C) toluene
solution (40 mL) of 1 (2.67 g, 0.010 mol) was slowly added via a
syringe to a precooled toluene solution (40 mL) of Ti(NMe2)4 (1.2
mL, 5 mmol). The reaction mixture was warmed to ambient
temperature and stirred overnight. Quantitative formation of bis-
(κN,κO-N-benzyl-3-tert-butylsalicylaldiminato)Ti(NMe2)2 was ob-
served. 1H NMR (200 MHz, CDCl3, 29 °C): δH 7.70 (s, 2H, CNH),
7.44-7.17 (m, 12H, H-Ar), 6.95-6.90 (m, 2H, H-Ar), 6.67 (t, 2H,
H-Ar), 4.41, 4.00 (d, 4H, CH2), 3.36 (s, 12H, NCH3), 1.60 (s, 18H,
CH3). MS (EI) m/z: 668 with appropriate isotope ratio for
C40H52N4O2Ti+. The amount of solvent was reduced to 40 mL, and
an excess of trimethylsilylchloride (12.7 mL, 0.1 mol, 20 equiv)
was added at ambient temperature. The reaction mixture was stirred
overnight followed by refluxing for 2 h in toluene and removal of
side-product residues at 70 °C under vacuum (3.25 g, 100%). Anal.
Calcd for C36H40Cl2 N2O2Ti: C, 66.37; H, 6.19; N, 4.30. Found:
3-Phenylpropyl-N-(3-tert-butylsalicylaldimine) (3) was pre-
pared by a similar method to that described for 1. tert-Butylsali-
cylaldehyde (2.5 mL, 0.0146 mol) and 3-phenylpropylamine (2.08
mL, 0.0146 mol) were used to obtain 3 (4.22 g, 98%). Anal. Calcd
for C20H25NO: C, 81.36; H, 8.53; N, 4.74. Found: C, 81.58; H,
1
C, 66.55; H, 6.61; N, 3.96. H NMR (200 MHz, CDCl3, 29 °C):
δH 7.74 (s, 2H, CNH), 7.74-6.85 (m, 16H, H-Ar), 5.00, 4.65 (d,
4H, CH2). 13C{1H} NMR (50.3 MHz, C6D6, 29 °C): δC 167.22
(CNH), 162.18 (CO), 139.60 (Ar), 138.23 (Ar), 136.52 (Ar), 134.15
(Ar), 133.30 (Ar), 130.92 (Ar), 129.66 (Ar), 129.54 (Ar), 129.10
(Ar), 128.69 (Ar), 126.03 (Ar), 125.48 (Ar), 121.33 (Ar), 63.95
(CH2), 35.77 (CH), 30.37 (CH3). MS (EI) m/z: 651 with appropriate
isotope ratio for C36H40Cl2N2O2Ti+.
1
8.73; N, 4.44. H NMR (200 MHz, CDCl3, 29 °C): δH 14.15 (s,
OH), 8.34 (s, NCNH), 7.33-7.07 (m, 7H, H-Ar), 6.82 (t, 1H, H-Ar),
3.61 (t, 2H, CNH), 2.76 (t, 2H, Ar-CH2), 2.07 (sept, 2H, CCH2C),
1.46 (s, 9H, CH3). 13C{1H} NMR (50.3 MHz, CDCl3, 29 °C): δC
165.84 (CNH), 160.78 (COH), 141.74 (Ar), 137.61 (Ar), 129.70
(Ar), 129.43 (Ar), 128.69 (Ar), 128.62 (Ar), 126.14 (Ar), 118.87
(Ar), 117.89 (Ar), 58.89 (CNH2), 35.05 (CMe3) 35.04 (Ar-CH2),
32.49 (CH2CCH2), 29.55 (CH3). MS(EI) m/z: 295 with appropriate
isotope ratio for C16H17NO+.
Bis(κN,κO-(2-phenylethyl)-N-3-tert-butylsalicylaldiminato)-
TiCl2 (2-Ti) was prepared by a similar method to that described
for 1-Ti. 2 (2.81 g, 0.010 mol) Ti(NMe2)4 (1.2 mL, 5 mmol) were
used. Bis(κN,κO-2-phenylethyl-N-3-tert-butylsalicylaldiminato)Ti-
(NMe2)2: 1H NMR (200 MHz, CDCl3, 29 °C): δH 7.95 (s, 2H,
CNH), 7.52, 7.48 (d, 2H, H-Ar), 7.30-7.02 (m, 12H, H-Ar), 6.79
(t, 2H, H-Ar), 3.28 (s, 12H, NCH3), 3.9-3.2 (m, 8H, CH2), 1.55
(s, 18H, CH3) ppm. Complex 2: 3.39 g, 100%. Anal. Calcd for
C36H40Cl2 N2O2Ti: C, 67.16; H, 6.53; N, 4.12; Found: C, 66.97;
Adamantylsalicylaldimine (4) preparation has been described
in the literature17 and was prepared here with high yield by the
method described for 1. Salicylaldehyde (2.5 mL, 1.146 g/mL,
0.0235 mol) and 1-adamantylamine (3.55 g, 0.0235 mol) were
mixed to obtain 4 (5.9 g, 98%). Anal. Calcd for C17H21NO: C,
1
79.96; H, 8.29; N, 5.49. Found: C, 80.27; H, 8.72; N, 5.26. H
1
NMR (200 MHz, CDCl3, 29 °C): δH 14.52 (s, OH), 8.32 (s, CNH),
7.21-7.32 (m, 2H, H-Ar), 6.79-7.32 (m, 2H, H-Ar), 2.18 (w, 3H,
CH), 1.83 (w, 6H, CH2), 1.73 (w, 6H, CH2). MS(EI) m/z: 255
with appropriate isotope ratio for C17H21NO+.
Adamantyl-N-(3-fluorosalicylaldimine) (5) was prepared by a
similar method to that described for 1. 3-Fluorosalicylaldehyde (1.0
H, 6.66; N, 4.02. H NMR (200 MHz, CDCl3, 29 °C): δH 7.64,
7.61 (d, 2H, H-Ar), 7.49 (s, 2H CNH), 7.40-6.80 (m, 14H, H-Ar),
4.00-3.90 (m, 4H, NCH2), 3.60-3.40 (m, 4H, NCH2), 3.15-2.95
(m, 4H, Ar-CH2), 2.90-2.70 (m, 4H, Ar-CH2), 1.63 (s, 18H, CH3).
13C{1H} NMR (50.3 MHz, CDCl3, 29 °C): δC 166.26 (CNH),
161.13 (CO), 139.53 (Ar), 138.24 (Ar), 137.84 (Ar), 134.10 (Ar),
(17) Zhao, G.-L.; Feng, Y.-L.; Hu, X.-C.; Kong, L.-C. Yingyong Huaxue
2003, 20, 806-808.
(18) Singh, R. V.; Tandon, J. P. Monatsh. Chem. 1980, 111, 1391-
1398.

Bis(salicylaldiminato) Titanium Catalysts
Organometallics, Vol. 26, No. 15, 2007 3697
132.61 (Ar), 129.51 (Ar), 128.91 (Ar), 128.80 (Ar), 126.89 (Ar),
124.64 (Ar), 121.46 (Ar), 63.15 (NCH2), 36.83 (Ar-CH2) 35.41
(CMe3), 30.13 (CH3). MS(EI) m/z: 679 with appropriate isotope
ratio for C38H44Cl2 N2O2Ti+.
Bis(κN,κO-N-adamantyl-3-tert-butylsalicylaldiminato)TiCl2 (6-
Ti). A precooled (-78 °C) solution of 6 (3.15 g, 0.010 mol) in
toluene (40 mL) was slowly added via syringe to a solution of TiCl4
(5 mmol, 0.55 mL) precooled (-78 °C) in toluene (40 mL). The
reaction mixture was warmed to ambient temperature and stirred
overnight. The product precipitated out and was isolated from the
liquid phase (3.69 g, 100%). Anal. Calcd for C42H56Cl2N2O2Ti: C,
Bis(κN,κO-(3-phenylpropyl)-N-(-3-tert-butyl-salicylaldimina-
to)TiCl2 (3-Ti) was prepared by a similar method to that described
for 1-Ti. 3 (2.95 g, 0.010 mol) and Ti(NMe2)4 (1.2 mL, 5 mmol)
were used. Bis(κN,κO-3-phenyl-1-propyl-N-3-tert-butylsalicylaldi-
minato)Ti(NMe2)2: 1H NMR (200 MHz, CDCl3, 29 °C): δH 7.98
(s, 2H, CNH), 7.53, 7.49 (d, 2H, H-Ar), 7.26-7.09 (m, 12H, H-Ar),
6.96, 6.93 (d, 2H, H-Ar), 6.80 (t, 2H, H-Ar) 3.26 (s, 12H, NCH3),
2.95-1.2 (m, 12H, CH2), 1.63 (s, 18H, CH3). The complex 3-Ti
(3.53 g, 100%): Anal. Calcd for C40H48Cl2 N2O2Ti: C, 67.90; H,
1
68.02; H, 7.63; N, 3.79. Found: C, 67.36; H, 7.63; N, 3.80. H
NMR (200 MHz, CDCl3, 29 °C): δ 8.50 (s, 2H, CNH), 8.02, 7.97
(d, 2H, H-Ar), 7.63-7.00 (m, 4H, H-Ar), 2.02 (b, 6H, CH), 1.82
(s, 12H, CH2), 1.58 (b, 12H, CH2), 1.46 (s, 18H, CH3). MS(EI)
m/z: 738 with appropriate isotope ratio for C42H56Cl2N2O2Ti+.
Bis(κN,κO-N-isopropylsalicylaldiminato)TiCl2 (7-Ti)19 was
prepared by a similar method to that described for 4-Ti. Hexam-
ethylsilazane (3.0 mL, 14.22 mmol), 7 (1.73 g, 10.60 mmol) (2.49
g, 100%), and TiCl4 (0.58 mL, 5.30 mmol) were used. The silylated
compound 7 (2.7 g, 10.60 mmol): 1H NMR (200 MHz, CDCl3,
29 °C): δ 8.69 (s, CNH), 7.914, 7.91 (d, H-Ar), 7.28, 7.72 (d,
H-Ar), 6.99 (t, H-Ar), 6.83, 6.79 (d, H-Ar), 3.54 (s, Me2CH), 1.28,
1.25 (d, 6H, CH3), 0.29 (s, 9H, SiMe3) ppm. MS(EI) m/z: 235
with appropriate isotope ratio for C13H21NOSi+. Complex 7-Ti:
2.34 g, 100%. Anal. Calcd for C38H44N2O2TiCl2: C, 54.20; H, 5.46;
1
6.84, N 3.96. Found: C, 68.09; H, 7.19, N 3.79. H NMR (200
MHz, CDCl3, 29 °C): δ (cis,cis) 8.20 (s, CNH), (cis) 8.02 (s, CNH),
(cis,cis) 7.84 (s, CNH), 7.65, 7.62 (d, 2H, H-Ar), 7.30-7.11 (m,
10H, H-Ar), 7.02 (t, 2H, H-Ar), 6.86, 6.83 (d, 2H, H-Ar), 3.70-
3.50 (m, 4H, NCH2), 2.45-2.20 (m, 4H, Ar-CH2), 1.9-1.7 (m,
4H, CCH2C), 1.63 (s, 18H, CH3) ppm. 13C{1H} NMR (50.3 MHz,
CDCl3, 29 °C): δC 169.37 (CNH), 166.76 (CNH), 166.55 (CNH),
162.45 (CO), 162.30 (CO), 161.71 (CO), 142.11 (Ar), 141.27 (Ar),
141.10 (Ar), 139.92 (Ar), 138.48 (Ar), 138.43 (Ar), 134.66 (Ar),
133.74 (Ar), 133.68 (Ar), 133.35 (Ar), 133.33 (Ar), 132.80 (Ar),
129.80 (Ar), 129.41 (Ar), 129.24 (Ar), 129.21 (Ar), 129.18 (Ar),
129.16 (Ar), 129.06 (Ar), 128.99 (Ar), 128.93 (Ar), 128.90 (Ar),
126.96 (Ar), 126.80 (Ar), 126.66 (Ar), 126.59 (Ar), 125.54 (Ar),
124.88 (Ar), 122.59 (Ar), 122.08 (Ar), 65.57 (NCH2), 62.02
(NCH2), 61.93 (NCH2), 35.92 (CMe3), 35.75 (CMe3), 35.66 (CMe3)
34.10 (Ar-CH2), 33.98 (Ar-CH2), 33.80 (Ar-CH2), 33.64 (CH2-
CCH2), 33.26 (CH2CCH2), 33.02 (CH2CCH2), 30.60 (CH3), 30.46
(CH3), 30.32 (CH3). MS(EI) m/z: 706 with appropriate isotope ratio
for C40H48Cl2 N2O2Ti+.
N, 6.32. Found: C, 54.05; H, 5.79; N, 6.46. MS(EI) m/z: 443 with
+
appropriate isotope ratio for C20H24N2O2TiCl2
.
Polymerization Experiments. Polymerizations were performed
in a Bu¨chi 1.0 L stainless steel autoclave equipped with Julabo
ATS-3 and Lauda RK 20 temperature-controlling units. Toluene
(200 mL) and the cocatalyst (MAO) were introduced to the argon-
purged autoclave reactor. Once the polymerization temperature was
reached, the reactor was charged with ethylene to the appropriate
pressure. Polymerizations were initiated by injecting 20 mL of the
catalyst precursor solution (2.5-20 µmol solution in toluene) into
the reactor. Mechanical stirring was applied at a speed of 800 rpm.
During the polymerizations the partial pressure of ethylene and the
temperature were maintained constant. Ethylene consumption was
measured using a calibrated mass flow meter and monitored together
with the autoclave temperature and pressure. The polymerization
reaction was terminated by pouring the contents of the reactor into
methanol, which was then acidified with a small amount of
concentrated hydrochloride acid. The solid polyethylene was
collected by filtration, washed with methanol, and dried overnight
at 70 °C.
Bis(κN,κO-N-adamantylsalicylaldiminato)TiCl2 (4-Ti). Hex-
amethylsilazane (3.0 mL, 14.22 mmol) was added to solution of 4
(2.7 g, 10.60 mmol) in dry CH2Cl2 (30 mL) via a syringe. The
reaction mixture was stirred overnight. The silylated phenoxyimine
was isolated as yellow, viscose liquid. The excess of hexamethyl-
silazane and byproducts were evaporated under vacuum at 50 °C.
1
The silylated compound 4: 3.47 g, 100%. H NMR (200 MHz,
CDCl3, 29 °C): δ 8.61 (s, CNH), 7.96, 7.92 (d, H-Ar), 7.28, 7.27
(d, H-Ar), 7.00 (t, H-Ar), 6.83, 6.79 (d, H-Ar), 2.18 (w, 3H, CH),
1.81 (w, 6H, CH2), 1.75 (w, 6H, CH2), 0.29 (s, 9H, SiMe3) ppm.
The precooled (-78 °C) silylated 4 (3.47 g, 10.60 mmol) in toluene
(40 mL) was slowly added via syringe to a precooled solution of
toluene (20 mL) and TiCl4 (0.58 mL, 5.30 mmol). The reaction
mixture was warmed to ambient temperature and stirred overnight.
Both toluene and the trimethylsilylchloride formed were removed
under vacuum at 50 °C. Complex 4-Ti: 3.32 g, 100%. Anal. Calcd
for C34H40Cl2 N2O2Ti: C, 65.08; H, 6.43; N, 4.46. Found: C, 65.21;
X-ray Crystallographic Study. Crystallographic data of com-
pound 1-Ti were collected with a Nonius KappaCCD area-detector
diffractometer at 173(2) K using Mo KR radiation (graphite
(19) Boveda Fontan, M. D.; Romero, J.; Sousa, A.; Gayoso, M. Acta
Cient. Compos. 1981, 18, 155-162.
(20) (a) Nonius. COLLECT; Nonius BV: Delft, The Netherlands, 2002.
(b) Sheldrick, G. M. SADABS; University of Go¨ttingen: Germany, 1996.
(c) Burla, M. C.; Camalli, M.; Carrozzini, G. L.; Cascarano, G.; Giacovazzo,
C.; Polidori, G.; Spagna, R. J. Appl. Crystallogr. 2003, 36, 1103. (d)
Sheldrick, G. M. SHELX-97; University of Go¨ttingen: Germany, 1997. (e)
Sheldrick, G. M. SHELXTL, Version 5.10; Bruker AXS Inc.: Madison,
WI, 1997.
1
H, 6.54; N, 4.31. H NMR (200 MHz, CDCl3, 29 °C): δ 8.05 (s,
2H, CNH), 7.60-6.80 (m, 8H, H-Ar), 2.45-1.40 (m, 30H,
adamantyl) ppm. MS(EI) m/z: 626 with approppriate isotope ratio
for C34H40Cl2N2O2Ti+.
Bis(κN,κO-N-adamantyl-3-fluorosalicylaldiminato)TiCl2 (5-
Ti) was prepared by a similar method to that described for 4-Ti.
Hexamethylsilazane (3.0 mL, 14.22 mmol), 5 (2.89 g, 10.60 mmol),
and TiCl4 (0.58 mL, 5.30 mmol) were used. The silylated compound
5 (3.66 g, 100%): 1H NMR (200 MHz, CDCl3, 29 °C): δ 8.61 (s,
CNH), 7.96, 7.92 (d, H-Ar), 7.28, 7.27 (d, H-Ar), 7.00 (t, H-Ar),
7.75-6.85 (m, 3H, H-Ar), 2.18 (w, 3H, CH), 1.81 (w, 6H, CH2),
1.75 (w, 6H, CH2), 0.29 (s, 9H, CH3) ppm. Complex 5-Ti: 3.16 g,
90%. Anal. Calcd for C34H38Cl2F2 N2O2Ti: C, 61.55; H, 5.77; N,
(21) Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.; Robb,
M. A.; Cheeseman, J. R.; Montgomery, J. A.; Vreven, T., Jr.; Kudin, K.
N.; Burant, J. C.; Millam, J. M.; Iyengar, S. S.; Tomasi, J.; Barone, V.;
Mennucci, B.; Cossi, M.; Scalmani, G.; Rega, N.; Petersson, G. A.;
Nakatsuji, H.; Hada, M.; Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa, J.;
Ishida, M.; Nakajima, T.; Honda, Y.; Kitao, O.; Nakai, H.; Klene, M.; Li,
X.; Knox, J. E.; Hratchian, H. P.; Cross, J. B.; Adamo, C.; Jaramillo, J.;
Gomperts, R.; Stratmann, R. E.; Yazyev, O.; Austin, A. J.; Cammi, R.;
Pomelli, C.; Ochterski, J. W.; Ayala, P. Y.; Morokuma, K.; Voth, G. A.;
Salvador, P.; Dannenberg, J. J.; Zakrzewski, V. G.; Dapprich, S.; Daniels,
A. D.; Strain, M. C.; Farkas, O.; Malick, D. K.; Rabuck, A. D.;
Raghavachari, K.; Foresman, J. B.; Ortiz, J. V.; Cui, Q.; Baboul, A. G.;
Clifford, S.; Cioslowski, J.; Stefanov, B. B.; Liu, G.; Liashenko, A.; Piskorz,
P.; Komaromi, I.; Martin, R. L.; Fox, D. J.; Keith, T.; Al-Laham, M. A.;
Peng, C. Y.; Nanayakkara, A.; Challacombe, M.; Gill, P. M. W.; Johnson,
B.; Chen, W.; Wong, M. W.; Gonzalez, C.; Pople, J. A. Gaussian 03;
Gaussian, Inc.: Pittsburgh, PA, 2003.
1
4.22. Found: C, 61.19; H, 5.46; N, 4.06. H NMR (200 MHz,
CDCl3, 29 °C): δ 8.63 (s, 2H, CNH), 7.10-6.80 (m, 6H, H-Ar),
2.46 (w, 6H, CH), 2.24 (w, 12H, CH2), 1.74 (w, 12H, CH2) ppm.
MS(EI) m/z: 662 with appropriate isotope ratio for C34H38Cl2F2
N2O2Ti+.

3698 Organometallics, Vol. 26, No. 15, 2007
Pa¨rssinen et al.
monochromator), 0.71073 Å. Data reduction: COLLECT.20a Ab-
sorption correction: SADABS.20b Structure solution: SIR 2002.20c
Refinement: SHELX-97.20d Graphics: SHELXTL.20e All non-
hydrogen atoms were refined anisotropically. Hydrogen atoms were
refined to calculated positions.
Theoretical Calculations. Geometry optimizations were per-
formed at the HF/3-21G* level, which has been shown to provide
reliable structures for group 4 transition metal complexes, especially
for titanium-based complexes.21,22 On the basis of earlier studies,
neither increasing the size of the basis set nor inclusion of electron
correlation at the MP2 level has a significant influence on the
geometries; however these would certainly increase calculation
times. Single-point MP2 calculations were performed to confirm
the relative stabilization order of conformations of the studied
titanium complexes. For single-point calculations, the basis set
6-31G* for C, H, O, and N and a generated basis set of equal level
for Ti were used. The stabilization orders produced by both methods
were generally in good agreement with each other. Geometry
minima were confirmed by frequency calculations. All calculations
were carried out by the Gaussian 03 program package.
Supporting Information Available: This material is available
free of charge via the Internet at http://pubs.acs.org.
(22) (a) Linnolahti, M.; Pakkanen, T. A. Macromolecules 2000, 33,
9205-9214. (b) Linnolahti, M.; Hirva, P.; Pakkanen, T. A. J. Comput.
Chem. 2000, 22, 51-64.
OM0610391