Dinuclear titanium complexes with methylphenylsilylene bridge between cyclopentadienyl rings. Synthesis, characterization and reactivity towards ethylene

Article abstract of DOI:10.1016/j.jorganchem.2010.01.037

The new ansa-titanocene dichloride [{(SiMePh)(η⁵-C₅H₄)₂}TiCl₂] (1) was prepared by one pot reaction, whereas synthesis of its methylated analogue [{(SiMePh)(η⁵-C₅Me₄)₂}TiCl₂] (3) was performed in two steps with isolation of corresponding silane intermediate SiMePh(HC₅Me₄)₂ (2). The reaction of 1 and 3 with TiCl₄ afforded the dinuclear complexes [(SiMePh){(η⁵-C₅R₄)TiCl₃}₂] (R = H (4) and R = Me (5)). The catalysts formed from 4 and 5 after their activation with excess MAO exhibited a modest activity in ethylene polymerization. The polymer products consisted of high molar mass linear polyethylenes with a broad molar mass distribution. The presence of three paramagnetic titanium species in the mixture 4/MAO was revealed by EPR spectroscopy. All new prepared compounds 1-5 were characterized by multinuclear NMR, EI-MS, IR, and solid-state structures of 1, 3 and 5 were determined by X-ray single crystal diffraction.

Full text of DOI:10.1016/j.jorganchem.2010.01.037

Journal of Organometallic Chemistry 695 (2010) 1425–1433
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Dinuclear titanium complexes with methylphenylsilylene bridge between
cyclopentadienyl rings. Synthesis, characterization and reactivity towards ethylene
a
b
c
a
a
a,
*
ˇ
ˇ
ˇ
Michal Horácek , Róbert Gyepes , Jan Merna , Jirí Kubišta , Karel Mach , Jirí Pinkas
a J. Heyrovsky´ Institute of Physical Chemistry of ASCR, v.v.i. Dolejškova 2155/3, 182 23 Prague 8, Czech Republic
b Department of Inorganic Chemistry, Charles University, Hlavova 2030, 128 40 Prague 2, Czech Republic
c Department of Polymers, Institute of Chemical Technology, Prague, Technická 5, 166 28 Prague 6, Czech Republic
a r t i c l e i n f o
a b s t r a c t
Article history:
The new ansa-titanocene dichloride [{(SiMePh)(
g
5-C5H4)2}TiCl2] (1) was prepared by one pot reaction,
5-C5Me4)2}TiCl2] (3) was performed in two
Received 30 November 2009
Received in revised form 26 January 2010
Accepted 31 January 2010
Available online 4 February 2010
whereas synthesis of its methylated analogue [{(SiMePh)(
steps with isolation of corresponding silane intermediate SiMePh(HC5Me4)2 (2). The reaction of 1 and
3 with TiCl4 afforded the dinuclear complexes [(SiMePh){(
5-C5R4)TiCl3}2] (R = H (4) and R = Me (5)).
The catalysts formed from 4 and 5 after their activation with excess MAO exhibited a modest activity
in ethylene polymerization. The polymer products consisted of high molar mass linear polyethylenes
with a broad molar mass distribution. The presence of three paramagnetic titanium species in the mix-
ture 4/MAO was revealed by EPR spectroscopy. All new prepared compounds 1–5 were characterized by
multinuclear NMR, EI-MS, IR, and solid-state structures of 1, 3 and 5 were determined by X-ray single
crystal diffraction.
g
g
Keywords:
Ansa-titanocene
Cyclopentadienyl
Dinuclear complexes
Ethylene polymerization
Crystal structure
Ó 2010 Elsevier B.V. All rights reserved.
1. Introduction
B(C6F5)3 or [Ph3C][B(C6F5)4] led to catalysts polymerizing ethylene
with activities in the range 8–30 kgPE molTiꢀ1 hꢀ1 atmꢀ1, while the
Monocyclopentadienyl titanium complexes in combination
with strong Lewis acids (methylaluminoxane (MAO) or B(C6F5)3)
form active species for polymerization of a wide range of olefins.
The most known applications are the polymerization of styrene
to syndiotactic polystyrene (sPS) [1,2] and the polymerization of
1,3-butadiene to highly cis-1,4-polybutadiene [3]. Another inter-
esting utilization was recently developed by Deckers et al. who
use of borate activator led to slightly higher activities in compari-
son to B(C6F5)3 [7,8]. The authors declared that the produced poly-
mers had high Mw (>300,000 g molꢀ1) and a linear microstructure.
In contrast, Pellechia et al. obtained the low molecular weight bu-
tyl branched (up to 50 branches/1000 carbons) polyethylene of
LLDPE type from a solely ethylene feed using the same catalytic
system [(C5Me5)TiMe3]/B(C6F5)3 [9]. Moreover, the formation of
high molar PE with isolated long chain branches (up to 25
branches/1000 carbons) was observed when the [(C5Me5)-
Ti(OBz)3]/mMAO (m denotes modified) system was used [10].
To our best present knowledge there is no study on the prepa-
ration of polyethylene using dinuclear monocyclopentadienyltita-
nium/MAO catalyst.
introduced the catalytic system [(g
5-C5H4CMe2Ar)TiCl3]/MAO
(where Ar = aryl) efficient with the selective ethylene trimerization
to 1-hexene [4]. The arene pendant group was proposed to behave
as a hemi-labile ligand, providing some stabilization for the reac-
tive metal center while still maintaining its accessibility to the
approaching ethylene molecule.
On the other hand, polymerization of ethylene catalyzed by
monocyclopentadienyl complexes lies outside the mainstream
due to their lower activity compared to group four metallocene
dichlorides [5]. Treatment of [(C5Me5)TiMe3] with B(C6F5)3 offered
the zwitterionic complex [(C5Me5)TiMe2][MeB(C6F5)3], which was
able to polymerize ethylene to a polymer with high Tm [6]. Extend-
ing the catalytic system to compounds of general formula
[(C5Me5)TiMe2E] (E = Me, C6F5, OC6F5, Cl) activated by either
Here, we present the preparation and characterization of new
ansa-titanocene dichlorides bearing methylphenylsilylene bridge
[{(SiMePh)(
the formation of dinuclear complexes
C5R4)TiCl3}2] (where R = H (4) and R = Me (5)) thereof. The reactiv-
ity of catalysts formed from 4 and 5 and [(SiMe2){(
5-C5H4)TiCl3}2]
g
5-C5R4)2}TiCl2] (where R = H (1) and R = Me (3)) and
[l -
-(SiMePh){(g5
g
(6) [11] by their activation with excess of MAO towards ethylene
has been tested. The impact of two titanium centers constrained
in close proximity along with the effect of a pendant phenyl group
residing at the silicon bridge on the catalytic performance will be
discussed.
* Corresponding author. Tel.: +420 2 8658 3735; fax: +420 2 8658 2307.
E-mail address: pinkas@jh-inst.cas.cz (J. Pinkas).
0022-328X/$ - see front matter Ó 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2010.01.037

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M. Horácek et al. / Journal of Organometallic Chemistry 695 (2010) 1425–1433
1426
its high solubility). The resulting white solid is exclusively 5,50-iso-
2. Results and discussion
mer as proved by NMR measurements of its CDCl3 solution (see
Section 4).
2.1. Synthesis of dinuclear titanium complexes
Ligand 2 was deprotonated with 2 equivalents of n-BuLi and the
dilithium salt formed in situ was treated with TiCl3(THF)3. The oxi-
dation of the intermediate ansa-titanocene monochloride was per-
formed by aqueous HCl. Complex 3 was obtained in the form of air-
and moisture-stable dark red crystals (directly suitable for single-
crystal X-ray diffraction) after crystallization of the crude product
from a CHCl3/MeOH mixture.
A general synthetic route to the dinuclear complexes 4 and 5
comprises of the respective synproportionation of 1 and 3 with
TiCl4 performed at elevated temperatures (Scheme 3). The reac-
tions were successfully conducted both in toluene solutions or in
neat TiCl4.
It should be noted that an acidolytic route to the
hexa(amido)dinuclear complex from the reaction of Ti(NMe2)4
and 2 was found to be unfeasible, as the reaction of ligand 2 with
2.1 molar equivalents of Ti(NMe2)4 failed to proceed even at
145 °C, apparently due to the low acidity of the ligand.
The preparation of titanocene dichloride 1 was accomplished as
depicted in Scheme 1. Although the preparation of the chelating
(C5Me4)2SiMePh ligand has already been published [12], our at-
tempt to reproduce the procedure led only to a low yield of the de-
sired ligand contaminated in addition by a variety of undefined
compounds. Therefore the synthesis of 1 was performed by
sequential addition of reagents in one-pot reaction arrangement.
Thus two equivalents of cyclopentadienylsodium solution in THF
were treated with dichloromethylphenylsilane in THF and the che-
lating ligand formed in situ was deprotonated by n-BuLi. The
dilithium salt was further reacted with TiCl4(THF)2 for 40 h and
after workup yielded complex 1 in a modest yield as air and mois-
ture stable reddish-brown fine crystals.
The synthesis of the permethylated analogue of 1 was carried
out in two steps with the isolation of the corresponding biscyclo-
pentadienylsilane 2 (Scheme 2). Dichloromethylphenylsilane was
reacted with two equivalents of tetramethylcyclopentadienyllithi-
um in THF, and after a short reflux, the mixture was treated with
one equivalent of hexamethylphosphoramide (HMPA). The use of
HMPA in the synthesis was found to be crucial, as the sole mixing
of dichloromethylphenylsilane with two equivalents of tetrame-
thylcyclopentadienyllithium led to the substitution of only one
chlorine atom on the silane even after a long reflux (6 days) in
THF. The 1H and 13C NMR spectra of the obtained chloromethyl-
phenyl(2,3,4,5-tetramethylcyclopentadienyl)silane agreed with lit-
erature data [13].
1H and 13C NMR spectra of the ansa-titanocene dichlorides
(1 and 3) and the dinuclear complexes (4 and 5) reflect an average
Cs molecular symmetry in solution. The 1H NMR spectra are consis-
tent with the presence of two equivalent cyclopentadienyl rings,
where each of them has four multiplet signals for the C5H4 protons
in 1 (dH in ppm: 5.96–6.00; 6.07–6.11; 7.20–7.24; 7.25–7.28) and
in 4 (dH in ppm: 6.18–6.22; 6.24–6.30; 6.48–6.53; 6.64–6.70). Sim-
ilarly, four singlet signals were observed for the C5Me4 methyls in 3
(dH in ppm: 1.53; 1.92; 2.07; 2.17) and three signals (due to the
overlap of two signals) in 5 (dH in ppm: 2.13; 2.31; 2.41). Both
the cyclopentadienyl protons in 1 and the methyl protons in 3 lo-
cated in vicinal positions to the bridging silicon atom showed
strong through space contacts with both phenyl CHortho protons
The ligand 2 was obtained predominantly as 5,50-isomer in a
purity about 92% (by GC–MS), and was used without any further
purification. Where it necessary, it could be purified by crystalliz-
ing from cold hexane (with a relatively low recoverability due to
(dH in ppm: CHortho/CH(C5H4): 7.85–7.90/5.96–6.00 in 1; CHortho
/
Scheme 1.
Scheme 2.

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M. Horácek et al. / Journal of Organometallic Chemistry 695 (2010) 1425–1433
1427
the presence of methyl substituents on the cyclopentadienyl rings.
The CE1–Ti–CE2 angle for 3 is as low as 132.34(3)° as opposed to
Scheme 3.
CMe(C5Me4): 7.88–7.94/1.53 in 3) and the methyl group bonded to
the bridging silicon atom (dH in ppm: SiMe/CH(C5H4): 0.88/6.07–
6.11 in 1; SiMe/CMe(C5Me4): 1.03/1.92 in 3). The latter effect is
however absent in the case of the dinuclear complexes 4 and 5
due to a free rotation around the Si–Cp bond.
The electron impact mass spectra of the ansa-titanocene dichlo-
rides show quite different features. While the molecular peak m/z
366 of 1 is a base peak, the molecular peak m/z 478 of 3 possesses
about half abundance of the base peak m/z 105. The molecular peak
of the dinuclear complexes has a low intensity, e.g. m/z 668 for 5 or
is absent for 4.
Fig. 1. Thermal ellipsoid plot (50% probability level) of 1. Hydrogen atoms omitted
for clarity.
The infrared spectra of all complexes display valence vibrations
of the phenyl C–H groups in the region 3037–3131 cmꢀ1
.
2.2. Crystal structure analyses and DFT studies
Compound 1 crystallized with an orthorhombic lattice (space
group Pnma). The molecule (Fig. 1) exhibits an exact Cs point group
symmetry as only one half of the formula unit is located in the
asymmetric part of the unit cell. The remaining part of the mole-
cule is generated by applying the mirror plane passing through
the central titanium atom and the two chlorine ligands; this plane
incorporates in addition the silicon atom together with the methyl
carbon atom and the whole phenyl substituent.
The coordination environment of the titanium atom is a distorted
tetrahedron consisting of two cyclopentadienyl rings and two chlo-
ride ligands. The effect of cyclopentadienyl bending caused by the
presence of the SiPhMe bridging group is manifested by the decrease
oftheCE(1)–Ti–CE(1)0 angle(CEandCE0 denotethetwoCpcentroids)
to 129.17° as compared with the values 130.72(4)° and 130.70(3)°
Fig. 2. Thermal ellipsoid plot (50% probability level) of 3. Hydrogen atoms omitted
for clarity.
for the two independent molecules of [(g
5-C5H5)2TiCl2] [14]. Other
structural features are within expected ranges; selected molecular
parameters are listed in Table 1 .
Compound 3 (Fig. 2) crystallized with a triclinic lattice (space
ꢀ
group P1). The cyclopentadienyl ring bending in this molecule
caused by the SiPhMe bridge is more significant than in 1 due to
Table 1
Selected bond lengths [Å] and angles [°] for 1.
Ti(1)–Cl(1)
Ti(1)–Cl(2)
Ti(1)–C(1)
Ti(1)–C(2)
Ti(1)–C(3)
Ti(1)–C(4)
Ti(1)–C(5)
Si(1)–C(1)
Si(1)–C(6)
Si(1)–C(12)
Cl(1)–Ti(1)–Cl(2)
CE1–Ti(1)–CE(1)#1
C(1)–Si(1)–C(1)#1
C(12)–Si(1)–C(6)
2.3621(13)
2.3528(13)
2.376(3)
2.355(3)
2.430(3)
2.423(4)
2.363(3)
1.866(4)
1.868(5)
1.860(5)
96.95(5)
129.17
90.2(2)
111.8(2)
Fig. 3. Thermal ellipsoid plot (50% probability level) of 5. Hydrogen atoms omitted
for clarity.
Symmetry transformations used to generate equivalent atoms: #1x, ꢀy + 1/2, z.

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M. Horácek et al. / Journal of Organometallic Chemistry 695 (2010) 1425–1433
1428
g
5-C5Me4)TiCl3 moie-
Table 2
The dinuclear complex 5 consists of two (
ties interconnected by a SiMePh bridge. Due to their steric de-
mands, these two (
5-C5Me4)TiCl3 moieties are mutually rotated
Selected bond lengths [Å] and angles [°] for 3.
g
Ti(1)–Cl(1)
Ti(1)–Cl(2)
Ti(1)–C(1)
Ti(1)–C(2)
Ti(1)–C(3)
Ti(1)–C(4)
Ti(1)–C(5)
Ti(1)–C(10)
Ti(1)–C(11)
Ti(1)–C(12)
Ti(1)–C(13)
Ti(1)–C(14)
Si(1)–C(1)
Si(1)–C(10)
Si(1)–C(19)
Si(1)–C(20)
CE(1)–Ti(1)–CE(2)
Cl(1)–Ti(1)–Cl(2)
C(1)–Si(1)–C(10)
C(19)–Si(1)–C(20)
2.3191(5)
2.3385(5)
2.3660(17)
2.4260(17)
2.5495(18)
2.5422(17)
2.3842(17)
2.3767(17)
2.4178(18)
2.5277(18)
2.5082(18)
2.3869(18)
1.8725 (18)
1.8759(18)
1.8636(19)
1.8777(18)
132.34(3)°
96.89(2)
(Fig. 3). All molecular parameters (see Table 3) of 5 in solid-state
are comparable with those of the previously published molecule
[{(SiMe2)(
A notable feature of the solid-state packing of 5 is the presence
of the anion- interaction between the phenyl substituent and one
chloride ligand (Fig. 4) in solid-state, providing an explanation for
the absence of any significant interactions in the same struc-
ture. This anion- interaction is only present in the solid-state –
g
5-C5Me4)2}TiCl2] [16].
p
p-p
p
its nonexistence in solution is proved by NMR spectroscopy (vide
supra) suggestive of an unhindered rotation of both cyclopentadi-
enyl rings around the Si–CCp bonds. Since solid-state anion-
p inter-
actions can be either of electrostatic nature or of a weak
r
interaction [17–19], we have conducted some DFT studies on the
target molecule.
92.96(8)
102.41(8)
According to these DFT results, the anion –
p interaction is
purely of electrostatic nature in the structure of 5 (Fig. 4). The
Mayer bond orders [20] between the atoms involved were found
to be negligible. Natural Bond Analysis [21] results performed on
the Kohn–Sham orbitals suggested also the covalent contribution
to be negligible, due to the lack of any significant chlorine lone pair
delocalization into any phenyl C–C or C–H bonds.
Table 3
Selected bond lengths [Å] and angles [°] for 5.
Ti(1)–Cl(1)
2.2195(8)
2.2447(8)
2.2435(8)
2.328(2)
2.337(2)
2.375(2)
2.374(2)
2.360(2)
2.2202(8)
2.2496(8)
2.2310(8)
2.346(2)
2.352(2)
2.365(3)
2.373(3)
2.361(3)
1.908(3)
1.896(3)
1.862(3)
1.880(3)
103.62(3)
103.07(3)
102.08(3)
110.56(11)
110.17(11)
Ti(1)–Cl(2)
Ti(1)–Cl(3)
Ti(1)–C(1)
Ti(1)–C(2)
Ti(1)–C(3)
Ti(1)–C(4)
Ti(1)–C(5)
Ti(2)–Cl(4)
2.3. Catalytic ethene conversion
Complexes 4, 5 and [l-(SiMe2){(g
5-C5H4)TiCl3}2] (6) [11] were
activated by excess of MAO and tested in ethene polymerization
at different conditions (Table 4). All studied catalytic systems
showed a rather low activity in the range 2–20 kgPE molTi with
an increasing activity in order 5 < 4 < 6. The order of activity re-
flects lower Lewis acidity of Ti centers in 5 compared to 4 and 6
due to a substantial electron-donating character of methyl groups
bonded to cyclopentadienyl ring. The observed phenomenon is
quite unexpected as about 10 times higher activity in polymeriza-
ꢀ1
Ti(2)–Cl(5)
Ti(2)–Cl(6)
Ti(2)–C(10)
Ti(2)–C(11)
Ti(2)–C(12)
Ti(2)–C(13)
Ti(2)–C(14)
Si(1)–C(1)
Si(1)–C(10)
Si(1)–C(19)
Si(1)–C(20)
Cl(1)–Ti(1)–Cl(2)
Cl(1)–Ti(1)–Cl(3)
Cl(2)–Ti(1)–Cl(3)
C(1)–Si(1)–C(19)
C(10)–Si(1)–C(20)
tion was found for [(
g
5-C5Me5)TiCl3]/MAO (215 kgPE molTiꢀ1 hꢀ1
5-C5H5)TiCl3]/MAO (16–23 kgPE
barꢀ1
)
in comparison to [(
g
molTiꢀ1 hꢀ1 barꢀ1) imputed to higher stability of the former system
toward decomposition [5,22]. The activity lower by about a factor
of two of 4 compared with 6 could possibly be assigned to the com-
petition between the phenyl ring and the ethylene molecule during
the coordination to the active titanium center in 4.
Volatiles from all experiments were analyzed by GC–MS to de-
tect the presence of low molar weight oligomers (mainly 1-hex-
ene). Nevertheless, 1-hexene (ca 20 mg) was produced only in
run 6 where the catalyst derived from 4 was used at a maximum
ethylene pressure with the productivity ca 0.2 kg1-hexene
137.45° for
are given in Table 2.
g
5-[(C5Me5)2TiCl2] [15]. Selected molecular parameters
Fig. 4. Isodensity surface (2%) color coded with the electrostatic potential (left) and orientation of the molecule within the isodensity surface (right) color legend of the
electrostatic potential: red <0.00, yellow = 0.05, green = 0.10, blue = 0.15, dark blue >0.20. (For interpretation of the references to color in this figure legend, the reader is
referred to the web version of this article.)

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M. Horácek et al. / Journal of Organometallic Chemistry 695 (2010) 1425–1433
1429
Table 4
Activity of 4–6/MAO in ethylene polymerization and characterization of prepared polyethylene samplesa.
Ab
Mw ꢁ 105
Mw/Mn (MWD)
Tm (°C)
Xc
c
d
e
Run
Cat.
Tpolym (°C)
p (bar)
mPE (g)
1
2
3
4
5
6
7
8
9
10
5
5
5
4
4
4
4
4
6
6
25
50
75
25
25
25
50
75
25
25
1
1
1
1
3
5
1
1
1
5
0.04
0.04
0.03
0.28
0.43
0.80
0.33
0.28
0.59
1.56
2
2
1
11
6
135.1
132.9
133.0
131.7
132.2
131.5
135.4
134.4
131.9
134.5
0.58
0.56
0.63
0.25
0.32
0.37
0.45
0.66
0.23
0.40
21.2
16.5
21.1
4.9
5.6
570.5
621.8
15.7
6
13
11
24
13
a
b
c
Polymerization conditions: [Ti] = 5 ꢁ 10ꢀ4 M, Ti/Al = 1/1000 (m/m), time 1 h, solvent toluene, total volume 50 ml, rpm 600.
Activity [kgPolymer molTiꢀ1 hꢀ1 barꢀ1].
Determined by GPC.
d
e
Determined by DSC.
Polymer crystallinity.
molTiꢀ1 hꢀ1 barꢀ1. The value obtained for the formation of 1-hex-
proximity by a short silicone bridge cannot be ruled out. Although
Ti(IV) species are more beneficial for ethylene polymerization [10],
the paramagnetic Ti(III) species formed (vide infra) could also con-
tribute to the activity of studied systems. DFT calculations pub-
ene is more close to the value obtained for [(
g
5-C5H5)TiCl3]/MAO
5-C5H4CMe3)TiCl3]/
(2 kg1-hexene molTiꢀ1 hꢀ1 barꢀ1)[23] and for [(
g
MAO (13 kg1-hexene molTiꢀ1 hꢀ1 barꢀ1)[4] than to the value of the
highly efficient 1-hexene producing catalyst [(
g
5-C5H4CMe2Ph)-
lished recently showed that the polymerization of ethylene on
TiCl3]/MAO (535 kg1-hexene molTiꢀ1 hꢀ1 barꢀ1) [24]. Therefore we
supposed that the role of a pendant phenyl group for ethylene tri-
merization in 4 is negligible. This observation is in accord with the
unfavourable Ti-arene coordination in the SiMe2-bridged species
CpTi(III)Et+Aꢀ (Aꢀ denote counteranionts CH3B(C6F5)3
or
ꢀ
B(C6F5)4ꢀ) is thermodynamically allowed although with a low
polymerization degree only [27].
generated from [(
[25].
g
5-C5H4SiMe2Ph)TiMe3] and [CPh3](B(C6F5)4]
2.4. EPR study of the 4/MAO system
The determination of microstructure of prepared PE matrices by
NMR spectroscopy was hampered by low samples solubility in
C2D2Cl4 even at 120 °C. Nevertheless, 1H NMR data indicate that
samples were highly linear (single resonance at 1.34 ppm). The lin-
earity of PE samples was further supported by 13C NMR spectra,
where only single signal at 30.00 ppm characteristic for methylene
unit of the main chain was observed. Melting temperatures deter-
mined by DSC (see Tm value in Table 4) of all prepared PE samples
are in the range 131.5–135.4 °C, typical for linear HDPE. Polymer
samples were also poorly soluble in 1,2,4-trichlorobenzene and
lack of solubility even at high temperatures precluded in some
cases determination of molecular weights by GPC. Polymers ob-
tained in runs 4–6 had high Mw in range 1.6–2.1 ꢁ 106 g/mol. At
higher reaction temperature (compare run 4 and 7, Table 4) Mw
was significantly lowered and molar weight distribution (MWD)
increased, reflecting increased extent of transfer reactions. Further-
more, MWD was dramatically broadened with increase of ethylene
pressure from 1 to 5 bar to extreme MWD values MWD = 570 at 3
bars (run 5) and MWD = 620 at 5 bars (run 6). Although MWD of
polyethylenes prepared by monocylopentadienyl titanium/MAO
Generally speaking, treating cyclopentadienyltitanium(IV) com-
plexes with various organoaluminium compounds leads to the for-
mation of paramagnetic species [28]. The formation of Ti(III)
species from 4 after adding MAO as potential active species was
therefore checked by EPR spectroscopy. The EPR spectrum of 4/
100 eq. MAO in toluene showed 3 singlet signals (Fig. 5) indicating
the formation of paramagnetic species with g values g = 1.9958
(
D
H = 0.318 mT), g = 1.9871
H = 1.381 mT). The last value is close to the one characteristic
-Cl(or Me))4Al2(Cl(or Me)4
(DH = 0.79 mT) and g = 1.9741
(D
for species of general formula CpTi(
l
arising from the reduction of Ti(IV) by free AlMe3 (see Section 4)
known to be contained in MAO [29]. Surprisingly, the formation
of Ti(III) hydrido species reported for the CpTiCl3/MAO mixture
yielding doublets in the EPR spectrum at g = 1.995 and g = 1.989
[30] was not observed for the case of the 4/MAO mixture.
catalysts varies from relatively narrow with MWD = 2.2 for [(g5
C5H5)TiCl3]/MAO [22], MWD = 2.3–2.5 for [(
5-C5H5)Ti(OBz)3]/
MAO (Bz = benzyl) [10], to broad one with MWD ca. 40 for [{(g5
-
g
-
C5H4(cyclohex-1,1-diyl)Ar}TiCl3]/MAO) [26], extra-high MWD val-
ues similar to those obtained from runs 5 and 6 are unexpected for
HDPE polymer prepared by metallocene/MAO system.
Extremely broad MWD could be explained by the presence of
more than one type of active species in the polymerization system.
In addition to fully alkylated dicationic species of general formula
[X{Cp0TiMe2}+
]
also partly alkylated species [X{Cp’TiMeCl}+
]
2
2
(where X = SiMePh or SiMe2; Cp0 =
g g
5-C5H5, 5-C5Me5) and their
combination [{Cp0TiMe2}+X{Cp’TiMeCl}+] should be considered.
The activity of mononuclear cationic monocyclopentadienyltitani-
um methylchloride species [(g
5-C5Me5)TiMeCl]+ in polymerization
of both ethylene or propylene was proved by Ewart et al. [7,8].
Likewise, other active species (e.g. monocationic dinuclear species)
arising from a mutual interaction of both metals forced to a close
Fig. 5. EPR spectrum of the system 4/MAO ([Ti] = 4.49 mM; Ti/Al = 1/100 (m/m)) in
toluene.

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M. Horácek et al. / Journal of Organometallic Chemistry 695 (2010) 1425–1433
1430
DFT studies have been carried out at the fermi cluster at the J.
3. Conclusions
´
Heyrovsky Institute of Physical Chemistry, Academy of Sciences
of Czech Republic, using Gaussian 03, Revision E.01 [34]. The calcu-
lations used the Becke exchange [35] and Perdew/Wang 91 corre-
lational [36] functionals. The input geometry was the one obtained
from X-ray single crystal diffraction. Calculations were done as sin-
gle-point using the 6–31+G(d,p) basis set [37] employed for all
atoms. After veryfing the internal stability of the final wavefunc-
tion [38], Mayer Bond Order [20] studies have been carried out.
Natural Bonding Analysis [21] was done by the NBO 5.G program
[39]. Visualization and examination of molecular orbitals and the
distribution of the electrostatic potential was accomplished by
Molden [40].
The dinuclear complexes 4 and 5 were readily prepared from
the corresponding ansa-titanocene dichlorides 1 and 3 via synpro-
portionation with TiCl4. Complexes 4 and 5 activated by excess
MAO exhibited a moderate to low activity in the polymerization
of ethylene producing high molecular weight linear polyethylene
with a broad MWD.
4. Experimental
All operations with air and moisture sensitive compounds were
performed using standard Schlenk techniques under atmosphere
of argon. THF, diethylether, hexane, and toluene were dried by dis-
tillation from sodium/benzophenone and stored over sodium mir-
ror. Dichloromethane was dried by distillation from CaH2 and
stored over molecular sieves (4 Å).
4.1. Preparation of [{(SiMePh)(g
5-C5H4)2}TiCl2] (1)
Neat Cl2SiMePh (5.9 g, 31 mmol) was added in several portions
to a cold (ꢀ80 °C) solution of cyclopentadienylsodium (31 ml, 2 M,
62 mmol) in THF (80 ml). The reaction mixture was warmed to
room temperature and then stirred for additional 5 h. The resulting
red-brown mixture was cooled to 0 °C, and n-BuLi (24.8 ml,.2.5 M,
62 mmol) was dropped. The mixture was stirred for 2 h at room
temperature and then transferred to a suspension of TiCl4(THF)2
(prepared in situ by reaction of TiCl4 (3.5 ml, 31 mmol) with 5 ml
of THF) in 80 ml of toluene. The mixture was stirred for 40 h, evap-
orated almost to dryness and the crude product was precipitated
by hexane (200 ml), washed several times with hexane and dried
on air. The light brown solid was washed with boiling hexane for
8 h in Soxhlet extractor and then extracted with boiling dichloro-
methane for 30 h. The product crystallized from dichloromethane
solution at ꢀ28 °C. The resulting red-brown microcrystals were
separated, washed with dichloromethane/hexane (1/1, v/v)
(20 ml), hexane (3 ꢁ 30 ml) and dried on air. Yield 1.8 g (16%).
n-BuLi (n-butyllithium) (1.6 M solution in hexane), dichlorom-
ethylphenylsilane and cyclopentadienylsodium (2 M in THF) were
obtained from Sigma Aldrich and used as received. Methylalumi-
noxane (10 wt% in toluene) was obtained from Sigma Aldrich and
the amount of free AlMe3 (15%) was estimated on the basis of 1H
NMR measurements [31]. TiCl4 was distilled from copper turnings
prior to use. HMPA (hexamethylphosphoramide) was distilled
from sodium and stored over 4A molecular sieves (WARNING!
HMPA is a carcinogenic reagent). Tetramethylcyclopentadiene (a
mixture of isomers) [32], TiCl3(THF)3 [33] and [l -
-(SiMe2){(g5
C5H4)TiCl3}2] (6) [11] were prepared by published procedures. 1H
(300.0 MHz), 13C (75.4 MHz) 29Si(59.6 MHz) NMR spectra of li-
gands and organometallic species were recorded on a Varian Mer-
cury 300 spectrometer in CDCl3 solutions at 293 K. Chemical shifts
(d/ppm) are given relative tetramethylsilane as internal standard.
1H and 13C NMR spectra of PE samples were measured in CD2Cl4
at 105 °C on a Bruker Avance 500 MHz spectrometer and are refer-
enced to residual solvent signal (5.99 ppm) for 1H and to the signal
of main PE chain at 30.00 ppm for 13C. EPR spectra were measured
on an ERS-220 spectrometer (Center for Production of Scientific
Instruments, Academy of Sciences of GDR, Berlin, Germany) oper-
ated by a CU-3 unit (Magnettech, Berlin, Germany) in the X-band.
g values were determined using an Mn2+ standard at g = 1.9860
(MI = ꢀ½line). EI-MS spectra were obtained on a VG-7070E mass
spectrometer at 70 eV. Crystalline samples in sealed capillaries
were opened and inserted into the direct inlet under argon. GC–
MS measurements were performed on a Thermo Focus DSQ using
the capillary column Thermo TR-5MS (15 m ꢁ 0.25 mm
ID ꢁ 0.25 mm). IR spectra of air sensitive samples were taken in
an air-protecting cuvette on a Nicolet Avatar FTIR spectrometer
in the range 400–4000 cmꢀ1. KBr pellets were prepared in a glove-
box Labmaster 130 (mBraun) under purified nitrogen. Melting
points were measured on a Koffler block (air sensitive compounds
were measured in sealed capillaries) and were uncorrected. SEC
data were measured on PL GPC 220 high-temperature chromato-
graph equipped with PL-220DRI and VISKOTEL 220R detectors.
Separation was performed at 160 °C on set of three PL gel columns
4.1.1. M.p. 230 °C (decomp.)
1H NMR (300 MHz, CDCl3): 0.88 (s, 3H, SiMe); 5.96–6.00 (m, 2H,
C(5)H, C5H4); 6.07–6.11 (m, 2H, C(2)H, C5H4); 7.20–7.24 (m, 2H,
C(3)H, C5H4); 7.25–7.28 (m, 2H, C(4)H, C5H4); 7.50–7.63 (m, 3H,
CHmeta and CHpara, SiPh); 7.85–7.90 (m, 2H, CHortho, SiPh). 13C
{1H}(CDCl3): ꢀ5.20 (SiMe); 105.17 (C(1), C5H4); 118.41, 121.29,
133.48, 137.88 (CH, C5H4); 129.03, 131.54, 134.63 (CH, Ph)
130.42 (Cipso, Ph). 29Si {1H}(CDCl3): ꢀ17.98 (SiMePh). EI-MS, m/z
(relative abundance): 369 (23), 368 (72), 367 (36), 366 (MÅ+,
100), 365 (13), 364 (11), 333 (13), 332 (15), 331 ([MꢀCl]+, 29),
330 ([MꢀHCl]+, 19), 329 (7), 295 (7), 294 ([Mꢀ2HCl]+, 18), 178
(6), 177 (12), 176 ([C10H8Ti]+, 58), 175 (8), 174 (9), 157 (13), 156
(6), 155 (39), 105 (18), 83 (13), 69 (14), 53 (13), 49 (13), 43 (9).
IR (KBr; cmꢀ1): 3131 (m); 3101 (s); 3090 (s); 3071 (vs); 3016
(m); 2896 (m); 1663 (vw); 1587 (w); 1483 (vw); 1453 (vw);
1428 (m); 1401 (s); 1372 (w); 1363 (vw); 1323 (w); 1263 (m);
1207 (vw); 1171 (s); 1115 (vs); 1078 (w); 1060 (m); 1042 (m);
998 (vw); 900 (vw); 852 (w); 835 (vs); 802 (vs); 743 (vs); 702
(s); 688 (w); 667 (m); 623 (w); 492 (vs); 436 (m); 405 (m). EA Anal.
Calc. for C17H16Cl2SiTi (367.18): C 55.61, H 4.39. Found C 55.47, H
4.35%.
(10
l
m MIXED-B, 300 ꢁ 7.5 mm) in 1,2,4-trichlorobenzene stabi-
lized by 0.025% of Santonox R at flow rate 1 ml minꢀ1. Polyethylene
molecular weights and distributions were evaluated on the basis of
PS calibration (23 standards 3 k–6 M) and corrected using univer-
sal calibration method (Viscotek TriSEC software). All the results
are averages of two measurements. Thermal behaviour of PE was
investigated by DSC (TA Instruments Q100) with both heating
and cooling rate 10 °C minꢀ1under nitrogen (50 cm3 minꢀ1). Melt-
ing temperatures and heats of fusion were obtained from second
heating run. Degree of crystallinity (Xc) was calculated based on
the value of heat of fusion 292 J gꢀ1 for a 100% crystalline PE.
4.2. Preparation of (methyl)(phenyl)bis(2,3,4,5-
tetramethylcyclopenta-2,4-dien-1-yl)silane (2)
A hexane solution of n-BuLi (1.6 M, 75 ml, 120 mmol) was
slowly dropped into a solution of tetramethylcyclopentadiene
(14.5 g, 119 mmol) in THF (500 ml). The resulting white suspen-
sion was stirred for 15 h, Cl2SiMePh (10.5 g, 55 mmol) was added
in one portion, and the mixture was refluxed for 16 h. Then, the
mixture was cooled to ꢀ78 °C and HMPA (9.9 g, 55 mmol) was
drop-wise added. The mixture was heated to 60 °C and stirred

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M. Horácek et al. / Journal of Organometallic Chemistry 695 (2010) 1425–1433
1431
for 4 h, causing the transformation of suspension to a yellowish
4.4. Preparation of [-(SiMePh){(g
5-C5H4)TiCl3}2] (4)
solution. The solution was cooled to room temperature and all vol-
atiles were removed in vacuum. The oily residue was shaken with
150 ml of water and the product was extracted in diethyl ether
(2 ꢁ 200 ml). Collected organic phases were washed by brine
(2 ꢁ 50 ml), water (50 ml) and dried over Na2SO4. Diethyl ether
was removed on a rotary evaporator and a yellow oily residue
was heated to 60 °C in vacuum (0.1 mm Hg) for 10 h to remove
unreacted tetramethylcyclopentadiene. The resulting yellow oily
liquid has a satisfactory purity (>92% by GC–MS). Yield 17.1 g
(85%). The storage of the product in a refrigerator at 5 °C led to
its solidification. The analytically pure sample was obtained by
recrystallization from hexane as a white solid.
An excess of TiCl4 (1.00 ml, 9.00 mmol) was added to a suspen-
sion of 1 (0.88 g, 2.39 mmol) in toluene (30 ml). The mixture was
heated to reflux for 17 h, causing gradual color change from red
to yellow-brown. All volatiles were removed in vacuum, the resi-
due was washed with hexane (10 ml), and repeatedly extracted
with toluene. Concentration and cooling of the toluene solution
gave 4 as yellow crystals. Yield 0.95 g (71%).
4.4.1. M.p. 150 °C
1H NMR (300 MHz, C6D6): 1.00 (s, 3H, SiMe); 6.18–6.22, 6.24–
6.30 (2 ꢁ m, 2 ꢁ 2H, C(3)H and C(4)H, C5H4); 6.48–6.53, 6.64–
6.70 (2 ꢁ m, 2 ꢁ 2H, C(2)H and C(5)H, C5H4); 7.11–7.23 (m, 3H,
CHmeta and CHpara, SiPh); 7.30–7.36 (m, 2H, CHortho, SiPh). 13C
{1H}(C6D6): ꢀ3.67 (SiMe); 126.72, 126.74, 130.06, 130.33 (CH,
C5H4); 128.53, 131.08, 135.49 (CH, SiPh); 131.32 (Cipso, SiPh);
134.33 (Cipso, C5H4). 29Si {1H}(C6D6): ꢀ18.11 (SiMePh). EI-MS, m/z
(relative abundance): 556 (MÅ+, not observed), 543 (8), 541
(MꢀMe]+, 9), 504 (15), 502 (25), 500 (20), 486 ([Mꢀ2Cl]+, 16),
425 (7), 423 (6), 368 (71), 367 (36), 366 ([MꢀTiCl4]+, 92), 365
(14), 333 (46), 332 (42), 331 ([MꢀTiCl4ꢀCl]+, 100), 330 (28), 297
(25), 296 ([MꢀTiCl4ꢀ2Cl]+, 85), 295 (20), 294 (33), 252 (18), 250
(11), 177 (14), 176 ([C10H8Ti]+, 62), 175 (12), 174 (15), 157 (27),
156 (15), 155 (71), 105 ([C6H5Si]+, 54), 85 (16), 83 ([TiCl]+, 40),
53 (24). IR (KBr; cmꢀ1): 3103 (m), 3068 (w), 3037 (w), 2963 (w),
2914 (w), 2843 (vw), 1589 9 (vw), 1484 (vw), 1429 (w), 1409
(m), 1369 (vw), 1312 (vw), 1259 (w), 1180 (w), 1112 (m), 1069
(w), 1048 (s), 919 (vw), 889 (vw), 842 (s), 796 (vs), 738 (m), 700
(w), 686 (vw), 633 (vw), 502 (w), 475 (m), 460 (m), 446 (w), 414
(vs). EA Anal. Calc. for C17H16Cl6SiTi2 (566.88): C 36.67, H 2.90.
Found C 36.49, H 2.85%.
4.2.1. M.p. 74 °C
1H NMR (300 MHz, CDCl3): 0.01 (s, 3H, SiMe); 1.69, 1.76, 1.88,
2.13 (4 ꢁ s, 4 ꢁ 6H, C5Me4H); 3.56 (br s, 2H, CH, C5Me4H); 7.16–
7.48 (m, 5H, SiPh). 13C {1H}(CDCl3): ꢀ9.61 (SiMe); 11.11, 11.20,
15.14, 15.25 (C5Me4H); 52.41 (CH, C5Me4H); 126.10, 128.77,
133.90 (CH, SiPh); 132.55, 132.83, 137.20, 137.26 (Cq, C5Me4H);
133.60 (Cipso, SiPh). 29Si {1H}(CDCl3): ꢀ2.75 (SiMePh). GC–MS, m/z
(relative abundance): 362 (M+Å; 4), 243 (6), 242 (26), 241
([MꢀC5Me4H]+; 100), 240 (10), 163 (12), 135 (27), 122 (7), 121
([C5Me4H]+; 52), 119 (10), 105 ([PhSi]+, 13), 91 (5), 59 (10). EA Anal.
Calc. for C25H34Si (362.63): C 82.80, H 9.45. Found C 83.07, H 9.57%.
4.3. Preparation of [{(SiMePh)(g
5-C5Me4)2}TiCl2] (3)
To a solution of the ligand 2 (4.03 g, 11.1 mmol) in THF (300 ml)
previously precooled to ꢀ50 °C was dropped n-BuLi (13.9 ml,
1.6 M, 22.2 mmol). The obtained orange solution vas allow to
warm to room temperature, stirred for 4 h and then TiCl3(THF)3
(4.12 g, 11.1 mmol) was gradually added. The resulting brown mix-
ture was refluxed for 33 h. The volume of the solution was reduced
to ca. 100 ml and then 200 ml of aqueous HCl was added at room
temperature. The separated waxy solid was washed by methanol
and crystallized from chloroform solution over layered by metha-
nol. The formed intense red crystals (suitable for X-ray analysis)
were isolated, washed with mixture chloroform/methanol (1:5, v/
v), methanol and dried on air. The second crop of crystals was ob-
tained from mother solution. Total yield 0.85 g (16%).
4.5. Preparation of [-(SiMePh){(g
5-C5Me4)TiCl3}2] (5)
An excess of TiCl4 (1.0 ml, 9.0 mmol) was added to solid titano-
cene dichloride 3 (0.12 g, 0.25 mmol). The mixture was heated to
135 °C with stirring for 21 h. After cooling to room temperature,
all volatiles were removed in vacuum and the product was ex-
tracted with 10 ml of CH2Cl2. The volume of orange solution was
concentrated to ca. 4 ml, and the solution was layered with hexane
(ca. 10 ml). After four days the grey-yellow precipitate was formed,
and was filtered off. The mother liquor was again concentrated and
stored in a freezer (ꢀ28 °C) for several days. Formed orange micro-
crystals were isolated, washed with hexane (2 ꢁ 4 ml) and dried in
vacuum. The combined hexane washings gave after several days a
second crop of crystals. Overall yield 0.14 g (84%).
4.3.1. M.p. 260 °C
1H NMR (300 MHz, CDCl3): 1.03 (s, 3H, SiMe); 1.53 (s, 6H,
C(5)Me, C5Me4); 1.92 (s, 6H, C(2)Me, C5Me4); 2.07 (s, 6H, C(4)Me,
C5Me4); 2.17 (s, 6H, C(3)Me, C5Me4); 7.43–7.51 (m, 3H, CHmeta
and CHpara, SiPh); 7.88–7.94 (m, 2H, CHortho, SiPh). 13C {1H}(CDCl3):
5.06 (SiMe); 13.73, 14.01, 16.26, 17.50 (C5Me4); 91.68 (C(1),
C5Me4); 128.42, 130.14, 134.25 (CH, Ph); 129.36 (C(5)); 131.44
4.5.1. M.p. 210 °C
1H NMR (300 MHz, C6D6): 1.46 (s, 3H, SiMe); 2.13 (s, 3H, C5Me4);
2.31 (s, 6H, C5Me4); 2.41 (s, 3H, C5Me4); 7.29–7.36 (m, 2H, SiPh);
7.38–7.45 (m, 3H, SiPh). 13C {1H}(C6D6): 2.18 (SiMe); 14.49, 14.77,
(C(2)); 137.85 (Cipso
,
Ph); 142.86 (C(3)); 144.94 (C(4)). 29Si
{1H}(CDCl3): ꢀ16.37 (SiMePh). EI-MS, m/z (relative abundance):
481 (15), 480 (40), 479 (23), 478 (MÅ+, 49), 445 (15), 444 (32),
443 ([MꢀCl]+, 34), 442 ([MꢀHCl]+, 55), 441 (10), 428 (18), 428
(16), 427 ([MꢀHClꢀMe]+, 35), 358 ([MꢀC5Me4]+, 10), 344 (13),
321 (16), 240 (18), 239 (68), 223 (19), 209 (18), 179 (17), 161
(18), 159 (26), 145 (27), 121 (58), 120 (37), 119 (42), 107 (15),
106 (13), 105 (100), 91 (43), 79 (17), 77 (23), 59 (29), 43 (31). IR
(KBr; cmꢀ1): 3065 (w); 3054 (vw); 3014 (w); 3004 (vw); 2951
(w); 2909 (m); 2869 (vw); 1558 (vw); 1541 (vw); 1507 (w);
1489 (vw); 1458 (w); 1428 (m); 1405 (w); 1378 (s); 1353 (w);
1327 (m); 1258 (w); 1134 (w); 1107 (s); 1019 (w); 829 (w); 801
(s); 785 (m); 765 (w); 743 (w); 708 (vs); 684 (m); 669 (w); 655
(m); 560 (vw); 495 (m); 479 (w); 457 (vs); 419 (vw). EA Anal. Calc.
for C25H32Cl2SiTi (479.40): C 62.64, H 6.73. Found C 62.55, H 6.70%.
18.01, 18.41 (C5Me4); 128.08, 130.55 (CH, Ph); 133.58 (Cipso
,
C5Me4); 136.45 (CH, Ph); 136.91 (Cipso Ph); 143.00, 143.30,
,
144.05, 144.44 (C5Me4). 29Si {1H}(C6D6): ꢀ19.29 (SiMePh). EI-MS,
m/z (relative abundance):670 (20), 669 (13), 668 (MÅ+, 22), 666
(12), 480 (43), 479 (34), 478 ([MꢀTiCl4]+, 60), 477 (21), 464 (28),
462 (35), 444 (23), 443 ([MꢀTiCl4ꢀCl]+, 30), 442 ([MꢀTiCl4ꢀHCl]+,
47), 441 (9), 428 (16), 427 ([Mꢀ2HClꢀMe]+, 25), 360 (21), 358 (34),
240 (30), 239 (100), 223 (30), 209 (25), 169 (42), 159 (30), 145 (33),
121 (65), 120 (19), 59 (42). IR (KBr): 3063 (vw), 3042 (vw), 2971
(w), 2920 (m), 2843 (w), 1588 (vw), 1471 (w), 1428 (m), 1383
(m), 1324 (m), 1255 (w), 1127 (w), 1103 (w), 1022 (w), 999
(vw), 827 (w), 792 (s), 739 (m), 717 (w), 702 (w), 681 (vw), 559
(vw), 490 (m), 471 (s), 406 (vs). EA Alal. Calc. for C25H32Cl6SiTi2
(669.09): C 44.88, H 4.82. Found C 44.83, H 4.81%.

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M. Horácek et al. / Journal of Organometallic Chemistry 695 (2010) 1425–1433
1432
Table 5
Crystal data and structure refinement for 1, 3 and 5.
1
3
5
Formula
C17H16Cl2SiTi
C25H32Cl2SiTi
C25H32Cl6SiTi2
Rel. Mol. Weight
Temperature (K)
Crystal system
Space group
a (Å)
367.19
200(1)
479.40
150(1)
triclinic
669.10
150(1)
orthorhombic
Pnma (No. 62)
26.0143(13)
8.1182(4)
7.4846(3)
90
monoclinic
P21/c (No. 14)
16.0334(5)
12.3749(4)
17.8280(4)
90
120.1791(18)
90
3057.83(15)
4
ꢀ
P1 (No. 2)
8.5266(2)
9.3937(2)
15.2355(4)
99.1190(14)
105.2732(15)
93.4474(16)
1155.66(5)
2
b (Å)
c (Å)
a
(°)
b (°)
90
90
c
(°)
V (Å3)
Z
1580.67(13)
4
1.543
D (g cmꢀ3
l
)
1.378
0.663
1.453
1.100
(mmꢀ1
)
0.944
F(0 0 0)
Crystal size (mm3)
Hmax (°)
h range
k range
752
504
1368
0.45 ꢁ 0.18 ꢁ 0.03
2.83; 27.50
ꢀ33/33
ꢀ10/10
ꢀ9/9
0.60 ꢁ 0.30 ꢁ 0.25
1.41; 27.57
ꢀ11/11
0.68 ꢁ 0.33 ꢁ 0.12
1.47; 27.49
ꢀ20/20
Hmin
;
ꢀ12/12
ꢀ16/12
‘ range
ꢀ19/19
ꢀ23/23
Reflections collected/unique
Data/restraints/parameters
Goodness-of-fit F
6697/1896
1896/2/117
1.145
18749/5284
5284/0/271
1.021
21076/6995
6995/0/316
1.036
R (I > 2
wR2 on all data (%)
(e Åꢀ3
r
(I)) (%)
4.85
12.00
1.190; ꢀ0.51
3.84
10.15
0.358; ꢀ0.605
3.95
9.52
0.547; ꢀ0.353
D
q
)
4.6. Catalytic reactions of dinuclear complexes with ethene
was solved by SIR-97 [41] and the structures were refined by the
least-squares method using the SHELXL-97 [42] program. All heavy
atoms were refined anisotropically; hydrogen atoms were put into
their theoretical positions and refined isotropically.
Crystal data and structure refinement details for 1, 3 and 5 are
given in Table 5.
The catalytic transformation of ethene was performed in a
semi-bath mode (the ethene pressure was keep constant during
process) in a 250 ml Büchi glass double jacked autoclave equipped
with a magnetic stirrer. The hot autoclave was evacuated and filled
with argon three times, then toluene, 0.5 g of decane (as an inter-
nal standard) and the solution of methylaluminoxane (10 wt% in
toluene; Ti/Al = 1/1000 (m/m)) were consequently injected. The
autoclave was thermostated to desired temperature and the tem-
perature was maintained by the external Pt100 sensor connected
to Julabo F31-C bath.
The argon atmosphere was replaced with ethene by cyclic pres-
suring and venting. The polymerization was started by injecting of
a desired amount of stock catalyst solution (final volume of poly-
merization solution was 50 ml and [Ti] = 5 ꢁ 10ꢀ4 M for all exper-
iments), followed by pressuring autoclave to the desired pressure.
After 1 h, the autoclave was vented, and a sample (ca 2 ml) was ta-
ken from a clear solution to analyze soluble components by GC–
MS. The residual mixture in autoclave was quenched with 10%
HCl in ethanol (80 ml). A precipitated polymer was stirred in acid-
ified ethanol for 1 h, filtered, washed with ethanol, acetone and
dried in vacuum to constant weight.
Acknowledgements
The financial support from the Grant Agency of the Academy of
Sciences of the Czech Republic (project KJB400400602), Ministry of
Industry and Trade of the Czech Republic (project No. FT-TA3/078)
and Ministry of Education, Youth and Sports (research programmes
MSM6046137302
acknowledged.
and
MSM0021620857)
is
gratefully
Appendix A. Supplementary material
CCDC 751822, 751823 and 751824 contain the supplementary
crystallographic data for compounds 1, 3 and 5, respectively. These
data can be obtained free of charge from The Cambridge Crystallo-
graphic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
Supplementary data associated with this article can be found, in
the online version, at doi:10.1016/j.jorganchem.2010.01.037.
4.7. Reaction of 4 with MAO
References
A Schlenk flask directly connected to an EPR tube was filled
with toluene solution of methylaluminoxane (10 wt% in toluene;
1.7 ml, 2.6 mmol) and a stock solution of 4 in toluene (4.49 mM,
2.8 ml, 13 lmol; Ti/Al = 1/100 (m/m)) was added. The resulting
brown-violet mixture was transferred into the EPR tube and mea-
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