Titanium complexes with modifiable pyrazolonato and pyrazolonato-ketimine ligands: Synthesis, characterization and ethylene polymerization behavior

Article abstract of DOI:10.1016/j.jorganchem.2009.09.019

Six titanium complexes bearing pyrazolonato and pyrazolonato-ketimine ligands have been synthesized and characterized. It was found that the ligand structure of the synthesized complexes has a significant effect on the catalytic performance of the complexes. The synthesized complexes were activated with MAO and their activities varied from negligible to high (up to 612 kg_PE/(mol_Ti h bar). The pyrazolonato-ketimine complex with a phenyl substituent in the imine part was the most active in the series and it was the only one producing polyethylenes with relatively narrow molecular weight distribution (M_w/M_n from 1.6 to 2.2).

Full text of DOI:10.1016/j.jorganchem.2009.09.019

Journal of Organometallic Chemistry 695 (2010) 11–17
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Titanium complexes with modifiable pyrazolonato and pyrazolonato-ketimine
ligands: Synthesis, characterization and ethylene polymerization behavior
*
Pertti Elo, Antti Pärssinen, Sari Rautiainen, Martin Nieger, Markku Leskelä, Timo Repo
Department of Chemistry, Laboratory of Inorganic Chemistry, University of Helsinki, P.O. Box 55, 00014 Helsinki, Finland
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 16 July 2009
Received in revised form 4 September 2009
Accepted 10 September 2009
Available online 29 September 2009
Six titanium complexes bearing pyrazolonato and pyrazolonato-ketimine ligands have been synthesized
and characterized. It was found that the ligand structure of the synthesized complexes has a significant
effect on the catalytic performance of the complexes. The synthesized complexes were activated with
MAO and their activities varied from negligible to high (up to 612 kgPE/(molTi h bar). The pyrazolonato-
ketimine complex with a phenyl substituent in the imine part was the most active in the series and
it was the only one producing polyethylenes with relatively narrow molecular weight distribution
(Mw/Mn from 1.6 to 2.2).
Keywords:
Polymerization
Ethylene
Ó 2009 Elsevier B.V. All rights reserved.
Catalyst
Titanium
O,N-ligand
1. Introduction
Depending on the catalyst structure hyperbranched polyethylenes,
block copolymers, copolymers with polar monomers and polyole-
Since the successful introduction of chiral Group IV metallocene
catalyst to the polymerization of olefins, intensive research in this
area has led to exploration of various well-defined transition metal
catalyst systems [1–3]. Due to this extensive research of cyclopen-
tadienyl and indenyl bearing complexes, lately non-metallocene
complexes have attracted more interest [4–7]. Many successful
non-metallocene Group IV complexes bearing, for example, amide
[8–12], b-diketiminates [13,14], phosphine-imide [15], imine-pyr-
rolidines [16,17], imido [18,19], alkoxide [20–23] and enaminoke-
tonato [24,25] ligands have been reported. Some of these catalysts
have been shown to exhibit high activities, comparable to those of
metallocene catalysts [8,15,16,18]. In addition to Group IV metal
complexes, notable achievements have been established among
Ni, Pd, Fe and Co complexes with diimine and diimine-pyridine li-
gands [26–28].
The work done with phenoxy-imine-catalysts (FI-catalysts) and
diimine complexes have shown that small changes in the ligand
structure around the metal center can lead to profound changes
in the performance of the polymerization catalysts [26,29]. By
varying the steric and electronic properties of the ligand frame-
work it is not only possible to enhance the activity of the catalyst
but also promote synthesis of well-defined polymer structures.
fins with narrow PDI through living polymerization are achievable
[30–34].
In general ketimine complexes have attracted less attention
then their aldimine counterparts. The lack of interest given to
ketimine catalysts may partly be explained by the fact that the syn-
thesis of the desired ligand precursors is not always straightfor-
ward [35]. However, ketimine type catalysts may have enhanced
properties when compared to aldimine analogs. For example Chen
et al. synthesized phenoxy-ketimine complexes which proved to
be more active in ethylene polymerization than corresponding sali-
cyl aldimine catalysts [36]. Also in contrast to aldimine analogs, the
phenoxy-ketimine catalysts have been shown to polymerize ethyl-
ene in living manner, even without fluorinated phenyl ring in the
imino-moiety [37]. In addition Coates et al. have utilized phen-
oxy-ketimine complexes in the polymerization of multiblock iso-
tactic polypropylene copolymers [38].
As an augmentation to our previous catalyst development
[39,40], we report herein the synthesis of as series of pyrazolonato-
and pyrazolonato-ketimine titanium dichloride complexes and
their usage as catalyst precursors in ethylene polymerization.
Two of these complexes have been previously synthesized (1-Ti
and 2-Ti) [41] but to the best of our knowledge no polymerization
experiments have been carried out with these compounds. Our
interest towards these complexes arouse from the fact that their li-
gand structures offer many sites that can be altered and thus afford
possibilities to effect the catalytic performance of these complexes.
* Corresponding author. Fax: +358 919150198.
E-mail address: timo.repo@helsinki.fi (T. Repo).
0022-328X/$ - see front matter Ó 2009 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2009.09.019

12
P. Elo et al. / Journal of Organometallic Chemistry 695 (2010) 11–17
2. Results and discussion
2.1. Synthesis and characterization of Ti-complexes
A general synthetic route for the titanium complexes is pre-
sented in Scheme 1. Pyrazolonato ligand precursors 1–2 and corre-
sponding b-diketonato complexes 1-Ti and 2-Ti were prepared
according to known literature procedures [41,42]. To introduce
desirable imine function into the ligand back-bone, new pyrazolo-
nato-ketimine ligand precursors 3–6 were synthesized using an
autoclave method we have previously reported [35]. As classical
methods of using BuLi or sodium were unsuccessful, titanium com-
plexes 3-Ti–6-Ti bearing these ligands were synthesized with a
straightforward manner by first mixing Et3N with a ligand precur-
sor and then adding this mixture to a solution of TiCl4. By this
method the desired complexes were obtained with moderate
yields (23–29%) as dark red powders.
According to NMR studies the pyrazolone-ketimine ligand pre-
cursors 3–6 are in enol-form, indicated by the broad singlet attrib-
uted to the OH-group at low field. Crystals of compounds 3 and 5
suitable for X-ray analysis were grown from saturated toluene
solutions. The corresponding structures are displayed in Figs. 1
and 2. Selected bond distances and angles for the compounds are
listed in Table 1. Interestingly the X-ray analysis revealed that in
the solid state these ligand precursors adopt a betaine configura-
tion, which is clearly evident when comparing the significant bond
Fig. 1. Molecular structure of the ligand 3. Displacement parameters are drawn at
50% probability level. Hydrogen atoms (except H(N)) are omitted for clarity.
distances. Both compounds have
a distance between C1–O1
(1.247(5) and 1.249(2) Å) resembling that of anionic oxygen
(ꢀ1.25 Å) [43]. As expected for betaine structure also the C6–N7
bond is slightly shorter (1.344(6) and 1.320(8)) than expected for
amino configuration (1.353 Å) but still noticeably longer than the
ones reported for imino-type structures (1.279 Å) [43]. The X-ray
structures of compounds 1 and 2 also exhibit strong hydrogen
bond between H(N) and O1 forming a six-member ring [44]. In
addition, according to the X-ray structure the aryl-ring attached
Fig. 2. Molecular structure of the ligand 5. Displacement parameters are drawn at
50% probability level. Hydrogen atoms (except H(N)) are omitted for clarity.
to the N2 atom is in the same plane as the pyrazolone ring, while
the other phenyl rings are out of plane. This indicates that this aryl-
ring attached to N2 atom belongs to the same planar conjugated
system formed by the betaine moiety (O1, C1, N2, N3, C4, C5, C6,
and N7).
In spite of numerous attempts, no crystals suitable for X-ray
structure analysis were obtained for complexes 1-Ti–6-Ti. It can,
however, be concluded based on NMR spectra that complexes
1-Ti and 4-Ti–6-Ti are C2 symmetric ones in solution. However,
the structure of a compound attributed to a reaction intermediate,
Scheme 1. Synthetic route for the complexes 1-Ti–6-Ti.

P. Elo et al. / Journal of Organometallic Chemistry 695 (2010) 11–17
13
Table 1
except 3-Ti exhibited low activities in ethylene polymerizations.
Catalysts 1-Ti/MAO and 2-Ti/MAO with b-diketonato ligands gave
unimodal polyethylene as a product, although with broad molecu-
lar weight distributions. From the O,N-type complexes, 3-Ti/MAO
behaved as a single-site catalyst producing unimodal polyethyl-
enes with a relatively narrow molecular weight distribution
whereas catalyst 4-Ti/MAO produced unimodal polyethylenes with
broad molecular weight distribution. The catalysts 5-Ti/MAO and
6-Ti/MAO, with alkyl substituent in the imine-group, produced bi-
modal polyethylenes with extremely broad molecular weight
distributions.
Selected bond lengths [Å] for compounds 3, 5 and 3-Ti*.
Compound 3
O1–C1
C1–C5
C5–C6
C6–N7
1.247(5)
1.441(6)
1.395(6)
1.344(6)
0.94(5)
N7–H7
Compound 5
O1–C1
C1–C5
C5–C6
C6–N7
1.2492(15)
1.4410(18)
1.4034(18)
1.3207(17)
1.4648(17)
0.884(12)
The catalyst 1-Ti/MAO revealed polymerization activity of 20 kg
PE/(molTi h bar) at 40 °C carried out polymerization. It seemed to
possess low thermal stability and as a result upon increasing poly-
merization temperature to 80 °C activity was reduced to 2 kg PE/
N7–C8
N7–H7
*
Compound 3-Ti
O1–C1
C1–C5
C5–C6
C6–N7
1.283(5)
1.429(6)
1.419(7)
1.327(6)
0.871(19)
N7–H7
Ti1–Cl1
Ti1–Cl2
Ti1–O1
2.3604(12)
2.3184(12)
1.941(3)
O1–Ti1–O1A
O1–Ti1–Cl2
O1A–Ti1–Cl2
Cl1–Ti1–Cl1A
180.00
88.53(10)
91.47(10)
180.00
*
Ti-3 , (Scheme 2) was obtained from a toluene solution and is dis-
played in Fig. 3. Selected bond distances and angles for this com-
*
plex are listed in Table 1. Ti-3 is a tetragonal bipyramide
coordinated complex with the oxygen atoms in axial position to
*
the titanium atom. The X-ray analysis also revealed that 3-Ti
has a crystallographic Ci-symmetry. The bond between the tita-
nium center and the oxygen atoms resemble to anionic ones and
as such is notably shorter than, for example, the bond between
titanium and oxygen in the case of TiCl4Á2THF (2.105(1) Å com-
pared to 1.941(3) Å in Ti-3*) [45]. The strong hydrogen bond be-
tween N(H) and oxygen atom found in the ligand precursor is
preserved but weakened [44]. However, two new hydrogen bonds,
one weak and one strong, between N(H) and the Cl-atoms Cl1 and
Cl2 are formed [44]. The obtained structure for the reaction inter-
mediate correlates well with the one obtained for related salicylal-
diminato titanium complex prepared through similar synthesis
route [46].
2.2. Ethylene polymerization
The complexes were activated with MAO and used as catalysts
for ethylene polymerization. Results of these experiments are
listed in Table 2. In general, after MAO activation all the complexes
Fig. 3. Molecular structure of the reaction intermediate 3-Ti*. Displacement
parameters are drawn at 50% probability level. Hydrogen atoms (except H(N)) are
omitted for clarity. The molecule possesses crystallographic Ci-symmetry.
Scheme 2. Formation of intermediate in the synthesis of complex 3-Ti.

14
P. Elo et al. / Journal of Organometallic Chemistry 695 (2010) 11–17
Table 2
plied here the steric bulk around the metal center was increased
by introducing isopropyl (iPr) groups to the 2 and 6 positions of
the imino-phenyl ring. This did not, however, improve the catalytic
performance but instead lead to significant decrease in polymeri-
zation activity. Similar decrease in activity has been observed for
some related Group IV metal complexes [49]. No clear effect of
monomer pressure was observed with catalyst 4Ti/MAO and also
an increase in polymerization temperature led to only a slight in-
crease in activity. The Mw of the polymers was found to be rela-
tively independent of the polymerization conditions.
The catalyst precursors were further modified by replacing the
aromatic group with a benzyl and an ethylphenyl moiety. FI-cata-
lysts with corresponding imino-groups, which we have previously
studied [50], displayed interesting properties in ethene polymer-
izations. The polymer obtained with catalyst 5Ti/MAO, bearing a
benzyl substituent in the imino group, was clearly bimodal and
the intensities of molecular weight fractions were found to be de-
pended on the polymerization temperature. With increasing tem-
perature the higher molecular weight fraction became more
dominant and correspondingly the intensity of the lower molecu-
lar weight fraction was decreased. The polymerization tempera-
ture also had a marked effect on the activity of the catalyst,
maximum activity being observed at 60 °C followed by a decrease
in higher temperatures. No clear effect of monomer pressure was
observed.
Formation of bimodal polymer was observed also when the
benzyl group was replaced with an ethylphenyl one. As with the
catalyst 5Ti/MAO, catalyst 6Ti/MAO produced bimodal polyethyl-
ene with the ratios of low- and high-molecular weight parts de-
pended on the polymerization temperature. Once again the
higher molecular weight fraction became dominant when poly-
merization was performed at elevated temperatures. However,
contradictory to behavior of 5Ti/MAO in the case of 6Ti/MAO also
the monomer pressure had an effect to molecular weight, increase
in pressure lead to increase in the intensity of the higher molecular
weight part. In general the benzyl substituted catalyst 5Ti/MAO
produced polymers with higher Mw then the ethylephenyl analog
6Ti/MAO.
The polymerization behavior of 5Ti/MAO mimics the one re-
ported for the FI-catalyst bearing benzyl substituent [50]. The
low activity of the analogous FI-catalyst was explained by the
benzyl substituent partially blocking the active polymerization
site. The formation of bimodal PEs was also attributed to this phe-
nomenon. However, interestingly 6Ti/MAO does not show similar
behavior as its FI-analog which exhibited high activity in ethene
polymerization and produced monomodal PE with narrow
MWD. At the moment the reason for the polymerization behavior
of these alkyl-substituted pyrazolonato-ketimine catalysts is not
clear.
Selected ethylene polymerization results with MAO activated complexes 1-Ti–6-Ti.
Run Complex p (bar)a Tp (°C)b Mw (kg/mol) Mw/Mn Activityc Tm (°C)d
1
2
3
4
5
6
7
8
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
4-Ti
4-Ti
4-Ti
4-Ti
5-Ti
5-Ti
5-Ti
5-Ti
5-Ti
6-Ti
6-Ti
6-Ti
6-Ti
6-Ti
4
4
4
2
6
4
4
4
2
6
4
4
4
2
6
4
4
4
2
6
4
4
4
2
6
4
4
4
2
6
40
60
80
60
60
40
60
80
60
60
40
60
80
60
60
40
60
80
60
60
40
60
80
60
60
40
60
80
60
60
1020
960
980
820
1080
600
620
890
950
760
1620
1020
690
1050
1450
650
630
600
670
610
1410/60
1200/50
1150/50
1170/50
1030/50
490/10
470/11
440/9
490/10
480/8
3.1
4.7
6.6
4.7
4.9
3.8
5.2
4.8
4.1
5.3
1.6
1.6
2.2
1.9
1.9
7.1
7.9
3.5
5.2
4.6
Broade
17
18
2
5
11
2
18
2
5
12
342
612
564
229
590
22
25
35
24
32
7
135
135
136
137
135
135
135
136
135
137
136
138
137
138
137
135
138
137
137
137
136
137
137
136
137
135
135
136
136
135
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
Broade 26
Broade
Broade 37
5
Broade
Broade
Broade
Broade
Broade
Broade
4
8
8
3
5
8
a
b
c
Monomer pressure.
Polymerization temperature.
Activity in kg PE/(molTi h bar).
Onset melting temperature of polyethylene.
Bi-modal molar mass distribution.
d
e
(molTi h bar). Increase in polymerization temperature led also to
broader molecular weight distributions. Seemingly the catalyst is
not stable at higher temperatures and that partial decomposition
of the complex structure may occur at elevated temperatures.
Increasing the monomer concentration did not lead to noticeable
changes in polymerization behavior with this catalyst. The other
O,O-type catalyst system 2-Ti/MAO behaved similarly with its
methyl analog 1-Ti/MAO in the terms of activity and molecular
weight distributions. It exhibited highest activity of 18 kg
PE/(molTi h bar) at 60 °C followed by activity decrease and broad-
ening of molecular weight distributions values at 80 °C. The molec-
ular weight values of the produced polyethylenes were lower than
achieved with corresponding catalyst 1-Ti/MAO revealing values of
600 000 to 950 000 g/mol.
Catalyst 3-Ti/MAO with an unsubstituted phenyl group in the
imine-part of the complex revealed the highest activities within
the studied catalyst precursors. The highest activity of 612 kg PE/
(molTi h bar) was achieved in 60 °C. The polymerization activity
was slightly decreased, to 564 kg PE/(molTi h bar), when the tem-
perature was increased to 80 °C. The molecular weight of the
formed polyethylene also depended on the polymerization tem-
perature, increased temperature lead to decreased molecular
weight values. The changes in molecular weight distribution values
with the changes in the polymerization temperature mimic the
behavior of a single-site catalyst. Also a slight broadening of
MWD can be seen upon temperature increase. Increasing the
monomer pressure from 2 bar to 4 bar lead to increased activity
while further increase to 6 bar did not enhance the activity of the
catalyst anymore.
3. Conclusions
Four new (3-Ti–6-Ti) and two previously known (1-Ti and 2-Ti)
titanium complexes bearing pyrazolonato and pyrazolonato-keti-
mine ligands have been synthesized and characterized. It was
shown that the ligand framework had a significant effect on both
the polymerization activity and on the molecular weight distribu-
tions of the resulting polymer product. Complexes were activated
with MAO and activities of the catalysts in ethylene polymerization
varied from 2 to 612 kg molÀ1 hÀ1 barÀ1. Moreover the GPC results
revealed that the most active catalyst 3-Ti was the only one that
behaved like a single-site catalyst and produced polymer with a
narrow molecular weight distribution. The rest of catalysts
revealed low polymerization activities despite the dramatic
changes in ligand environment from O,O to O,N. The polymeriza-
Using sterically bulky substituents in the imine-moiety is
known to enhance the catalytic activity of late transition metal
catalysts [47–48]. To investigate if the same concept could be ap-

P. Elo et al. / Journal of Organometallic Chemistry 695 (2010) 11–17
15
tion behavior bears a resemblance to related phenyl and alkylphe-
nyl substituted FI-catalysts [49,50]. The remarkable increase in
activity can be possibly observed when the ligand environment
of complex 3-Ti is modified by using fluorinated phenyl substitu-
ent instead of plain phenyl ring [28,51].
13C{1H} NMR (CDCl3, 50.3 MHz, 302 K): d = 21.57 (CH3), 25.32
(CH3) 28.76 (CH, iPr), 98.66 (CH), 119.66 (CH), 123.29 (Ar),
123.29 (Ar), 124.60 (Ar), 127.06 (Ar), 127.29 (Ar), 128.36 (Ar),
128.65 (Ar), 128.73 (Ar), 129.20 (Ar), 129.65 (Ar), 129.95 (Ar)
131.86 (Ar), 133.57 (Ar), 138.97 (Ar), 145.22 (Ar), 151.16 (Ar),
165.66(C@N), 166.33 (C@N).
Anal. Calc. for C34H33N3O: C, 81.73; H, 6.66; N, 8.41. Found:
81.75; H 6.69; N, 8.39%.
4. Experimental
Complexes 1-Ti and 2-Ti have been previously published and
they were prepared according to known literature procedure
[36,37].
All complex syntheses and polymerization experiments were
performed under an argon atmosphere using standard Schlenk
techniques. Toluene was dried over sodium flakes and distilled be-
fore use. Triethylamine was dried over calcium hydride and dis-
tilled before use. TiCl4 was purchased from Fluka and used as
received. Other reagents of high purity grade were purchased from
commercial sources and used as received. MAO (30% in toluene)
was obtained from Borealis Polymers Ltd.
Polymerization experiments were conducted in 1-L Büchi steel
autoclave. Autoclave was charged with 200 mL of dry toluene,
cocatalyst (MAO) and heated to desired temperature. Autoclave
was saturated with ethylene and polymerization was initiated by
addition of precatalyst solution. The monomer pressure, tempera-
ture and monomer consumption were controlled by real-time
monitoring. Polymerization was quenched with 10% HCl solution
in methanol, polymer was precipitated quantitatively by pouring
the solution into methanol (400 mL), acidified with a small amount
of HCl. Obtained polymer was washed several times with methanol
and water followed by drying at 60 °C.
NMR spectras were recorded in CDCl3 at 25 °C on a Varian
Gemini 200 spectrometer operating at 200 MHz (1H NMR) and
50.286 MHz (13C NMR). Elemental analyses were performed with
an EA 1110 CHNS-O CE instrument. EI mass spectra were acquired
using a JEOL-SX102 instrument. DSC measurements (melting
point) were performed using a Perkin–Elmer DSC-2, calibrated
with indium (temperature scanning 10 °C/min). The scan area
was from 25 to 232 °C. Molar masses and molar mass distributions
of polyethylene samples were determined with a Waters Alliance
GPCV 2000 high temperature gel chromatographic device having
HMW7, 2*HMWGE, and HMW2 Waters Styrogel columns. Mea-
surements were performed in 1,2,4-trichlorobentzene (TCB) at
160 °C relative to polyethylene standards, and 2,6-di-tert-butyl-4-
methylphenol was used as a stabilizer. Chromatograms were cali-
brated using linear polystyrene standards.
4.2. {1,3-diphenyl-4-[phenyl(phenylimino)methyl]-pyrazolone-5}TiCl2
(3-Ti)
3 (2.0 g, 4.81 mmol) was dissolved in 75 ml toluene, cooled
down to À78 °C and 5 equivalents (2.44 g, 24.07 mmol) of Et3N
was added to solution. The solution was added to a pre-cooled
(À78 °C) solution of TiCl4 (0.45 g, 2.4 mmol of TiCl4 in 40 ml of tol-
uene). The resulting mixture was allowed to warm to room tem-
perature and stirred for 48 h. The solution was then filtered
through Celite and solvent was removed in vacuo. To remove
Et3N residues, product was kept under vacuum in 40 °C for 20 h.
The crude product was recrystallized from saturated toluene solu-
tion with yield of 28%.
1H NMR (CDCl3, 200 MHz, 302 K): d = 6.74–7.40 (m, 36H, Ar),
8.12 (m, 4H, H–Ar).
13C{1H} NMR (CDCl3, 50.3 MHz, 302 K): d = 100.10, 119.52,
124.26, 124.70, 125.97, 127.28, 127.31, 127.90, 128.43, 128.68,
128.84, 129.35, 130.04, 130.13, 133.40, 137.42, 138.90, 151.26,
162.72 (C@N), 165.89 (C@N).
Anal. Calc. for C56H40Cl2N6O2Ti: C 70.97; H, 4.25; N, 8.87. Found:
71.08; H 4.31; N 8.79%.
MS(EI) m/z: 912 (M–Cl) 876 (M–2Cl) 462 (M–2Cl–L) (L = ligand).
4.3. 4-[(2,6di-isopropylphenylimino)(phenyl)methyl]-1,3-diphenyl-
pyrazolone-5} TiCl2 (4-Ti)
Complex 4-Ti was prepared by a similar method to that de-
scribed for 3-Ti with a yield of 26%.
1H NMR (CDCl3, 200 MHz, 302 K): d = 0.98 (d, 3JHH = 6.0 Hz, 12H,
3
CH3), 1.16 (d, JHH = 6.1 Hz, 12H, CH3), 3.18 (m, 4H, CH), 6.72–7.27
(m, 28H, H–Ar) 7.38–7.46 (m, 4H, H–Ar) 8.15 (m, 4H, H–Ar).
13C{1H} NMR (CDCl3, 50.3 MHz, 302 K): d = 21.63 (CH3), 25.36
(CH3) 28.94 (CH, iPr), 98.03 (CH), 119.87 (CH), 123.28 (Ar),
123.30 (Ar), 124.63 (Ar), 127.11 (Ar), 127.28 (Ar), 128.35 (Ar),
128.66 (Ar), 128.73 (Ar)x, 129.22 (Ar), 129.68 (Ar), 129.98 (Ar)
131.93 (Ar), 133.60 (Ar), 139.01 (Ar), 145.20 (Ar), 151.19 (Ar),
165.74(C@N), 166.45 (C@N).
The ligand precursors 1–2 and corresponding complexes 1-Ti
and 2-Ti were synthesized according to known literature proce-
dure [41,42]. The synthesis of precursors 3 and 5–6 we have re-
ported previously [35]. Ligand precursor 4 was synthesized in a
similar manner as precursors 3 and 5–6 with the following
conditions.
Anal. Calc. for C68H64Cl2N6O2Ti: C, 73.18; H, 5.78; N, 7.53.
Found: C, 73.24; H, 5.85; N, 7.49%.
4.1. 4-[(2,6di-isopropylphenylimino)(phenyl)methyl]-1,3-diphenyl-
pyrazolone-5} (4)
MS(EI) m/z: 1116(M), 1081 (M–Cl), 1045 (M–2Cl), 546 (M–2Cl–
L), 499 (L) (L = ligand).
1-Phenyl-3-phenyl-4-benzoyl-pyrazolone-5 (1.50 g, 3.61 mmol)
was dissolved in 25 ml of MeOH in a test tube. 2,6 Di-isopropylan-
iline (0.64 g, 3.61 mmol), Na2SO4 (2.60 g, 18.05 mmol) and a cata-
lytic amount of formic acid were added to solution. Test tube
was placed on steel autoclave and heated to 200 °C, as a result
pressure increased to 20 bars. The reaction mixture was vigorously
stirred for 16 h. Product was extracted from sodium sulfate with
Et2O and the solvents were removed under reduced pressure. Com-
pound 4 was purified by recrystallization from propanol. Yield 38%.
4.4. {4-[(benzylimino)(phenyl)methyl]-1,3-diphenyl-pyrazolone-
5}TiCl2 (5-Ti)
Complex 5-Ti was prepared by a similar method to that de-
scribed for 3-Ti with a yield of 23%.
3
1H NMR (CDCl3, 200 MHz, 302 K): d = 4.92 (d, JHH = 6.2 Hz, 4H,
3
CH2), 6.93–7.56 (m, 36 H, H–Ar), 8.13 (d, 4H, JHH = 8.2 Hz, H–Ar).
13C{1H} NMR (CDCl3, 50.3 MHz, 302 K): d = 48.89 (CH2), 98.08
(CH), 99.95 (CH), 119.67 (Ar), 127.16 (Ar), 127.89 (Ar), 126.87
(Ar), 128.09 (Ar),128.07 (Ar), 128.49 (Ar), 128.53 (Ar), 128.65 (Ar),
128.98 (Ar), 129.72 (Ar), 131.95 (Ar), 133.21 (Ar), 136.69 (Ar),
139.19 (Ar), 151.23 (Ar), 166.03 (C@N), 166.69 (C@N).
3
1H NMR (CDCl3, 200 MHz, 302 K): d = 0.95 (d, JHH = 6.1 Hz, 6H,
3
CH3), 1.14 (d, JHH = 6.1 Hz, 6H, CH3), 3.07 (m, 2H, CH), 6.74–7.23
(m, 14H, H–Ar), 7.38–7.42 (m, 2H, H–Ar)), 8.14 (m, 2H, H–Ar),
13.19 (s, 1H, OH).

16
P. Elo et al. / Journal of Organometallic Chemistry 695 (2010) 11–17
Anal. Calc. for C58H44Cl2N6O2Ti: C, 71.39; H, 4.55; N, 8.61.
5. Supplementary material
Found: 71.49; H, 4.60; N, 8.57%.
MS(EI) m/z: 940 (M–Cl) 905 (M–2Cl) 476 (M–2Cl–L) 429 (L)
(L = ligand).
CCDC 738034, 738035 and 738036 contain the Supplementary
crystallographic data for compounds 3, 5 and 3-Ti*. These data
can be obtained free of charge from The Cambridge Crystallo-
graphic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
4.5. {4-[(phenethylimino)(phenyl)methyl]-1,3-diphenyl-pyrazolone-
5} TiCl2 (6-Ti)
Acknowledgements
Complex 6-Ti was prepared by a similar method to that de-
scribed for 3-Ti with a yield of 29%.
Financial support for this work from Academy of Finland, pro-
jects 209739 and 123248 is greatly acknowledged. Warm thanks
to Sami Lipponen for the help with GPC measurements of the poly-
mer products.
3
1H NMR (CDCl3, 200 MHz, 302 K): d = 2.91 (t, JHH = 7.4 Hz) 4H,
3
CH2), 3.47 (t, JHH = 7.1 Hz, 4H, CH2), 6.80–7.57 (m, 36, H–Ar),
3
8.14 (d, JHH = 8.8 Hz, 4H, H–Ar).
13C{1H} NMR (CDCl3, 50.3 MHz, 302 K): d = 37.25 (CH2), 47.02
(CH2), 98.76 (CH), 120.28 (CH), 124.56 (Ar), 126.87 (Ar), 127.05
(Ar), 127.22 (Ar), 127.90 (Ar), 128.36 (Ar), 128.48 (Ar), 128.69
(Ar), 128.98 (Ar), 129.83 (Ar), 129.94 (Ar), 134.12 (Ar), 137.45
(Ar), 139.23 (Ar), 151.28 (Ar), 165.94 (C@N), 167.13 (C@N).
Anal. Calc. for C60H48Cl2N6O2Ti: C, 71.79; H, 4.82; N, 8.37;
Found: C, 71.83; H, 4.84; N, 8.34%.
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Yellow crystals, C28H21N3O, M = 415.48, crystal size 0.48 Â
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4.6.2. Compound 5
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21881 reflexes
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= 0.076 mmÀ1
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1.231 Mg mÀ3
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,
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