Novel titanium (IV) complexes with 1,2-diolate ligands: Synthesis, structure and catalytic activities in ultra-high molecular weight polyethylene production

Article abstract of DOI:10.1016/j.jorganchem.2018.09.014

A series of titanium (IV) complexes 3a-f stabilized by 1,2-diolate ligands 2 a-e have been synthesized. Structures of complexes 3d and 3e have been determined by X-ray diffraction. Titanium atoms in these complexes have a distorted square-pyramidal environment. All resulting complexes are highly active in ethylene polymerization in the presence of {3Et₂AlCl + MgBu₂} or {1.5Et₃Al₂Cl₃ + MgBu₂} binary co-catalysts. In the latter case, higher molecular weights of UHMWPE samples (up to 7.7 10⁶) are achieved. Obtained polymers are suitable for the modern processing methods – the solvent-free solid state formation of super high-strength (over 2.0 – 2.8 GPa) and high-modulus (up to 145 GPa) oriented film tapes.

Full text of DOI:10.1016/j.jorganchem.2018.09.014

Accepted Manuscript
Novel titanium (IV) complexes with 1,2-diolate ligands: Synthesis, structure and
catalytic activities in ultra-high molecular weight polyethylene production
Vladislav A. Tuskaev, Svetlana Ch Gagieva, Dmitrii A. Kurmaev, Victor N. Khrustalev,
Pavel V. Dorovatovskii, Elena S. Mikhaylik, Evgenii K. Golubev, Mikhail I. Buzin,
Sergey V. Zubkevich, Nikolay A. Kolosov, Galina G. Nikiforova, Viktor G. Vasil'ev,
Boris M. Bulychev
PII:
S0022-328X(18)30712-5
10.1016/j.jorganchem.2018.09.014
JOM 20571
DOI:
Reference:
To appear in: Journal of Organometallic Chemistry
Received Date: 11 August 2018
Revised Date: 17 September 2018
Accepted Date: 18 September 2018
Please cite this article as: V.A. Tuskaev, S.C. Gagieva, D.A. Kurmaev, V.N. Khrustalev, P.V.
Dorovatovskii, E.S. Mikhaylik, E.K. Golubev, M.I. Buzin, S.V. Zubkevich, N.A. Kolosov, G.G. Nikiforova,
V.G. Vasil'ev, B.M. Bulychev, Novel titanium (IV) complexes with 1,2-diolate ligands: Synthesis, structure
and catalytic activities in ultra-high molecular weight polyethylene production, Journal of Organometallic
Chemistry (2018), doi: https://doi.org/10.1016/j.jorganchem.2018.09.014.
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ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT
Novel titanium (IV) complexes with 1,2-diolate ligands: synthesis,
structure and catalytic activities in ultra-high molecular weight
polyethylene production
Vladislav A. Tuskaeva,b*, Svetlana Ch. Gagievaa,b, Dmitrii A. Kurmaev a, Victor
e
N. Khrustalev c, d, Pavel V. Dorovatovskii , Elena S. Mikhaylikb,e, Evgenii K.
Golubevb,e, Mikhail I. Buzinb, Sergey V. Zubkevicha, Nikolay A. Kolosova, Galina
G. Nikiforovab, Viktor G. Vasil’ev b, Boris M. Bulycheva
aDepartment of Chemistry, M. V. Lomonosov Moscow State University,1 Leninskie Gory, 119992
Moscow, Russian Federation
bA. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences,28 ul.
Vavilova, 119991 Moscow, Russian Federation
cInorganic Chemistry Department, Peoples’ Friendship University of Russia, 117198 Moscow,
Miklukho-Maklay St., 6, Russia
d National Research Center “Kurchatov Institute”, Moscow, Russia
e Enikolopov Institute of Synthetic Polymer Materials, Russian Academy of Sciences,
Profsoyuznaya Str., 70, 117393 Moscow, Russian Federation
KEYWORDS Ziegler-Natta Polymerization, Titanium, OO-ligands, UHMWPE
Corresponding Author *E-mail: tuskaev@yandex.ru.
ABSTRACT A series of titanium (IV) complexes 3a-f stabilized by 1,2-diolate ligands 2 a-e have
been synthesized. Structures of complexes 3d and 3e have been determined by X-ray diffraction.
Titanium atoms in these complexes have a distorted square-pyramidal environment. All resulting
complexes are highly active in ethylene polymerization in the presence of {3Et2AlCl + MgBu2}
or {1.5Et3Al2Cl3 + MgBu2} binary co-catalysts. In the latter case, higher molecular weights of
UHMWPE samples (up to 7.7 106) are achieved. Obtained polymers are suitable for the modern
processing methods – the solvent-free solid state formation of super high-strength (over 2.0 – 2.8
GPa) and high-modulus (up to 145 GPa) oriented film tapes.
1.
Introduction
Unique properties of UHMWPE make it one of the most promising modern construction
materials, however, the high viscosity of its melts makes it difficult to use conventional methods
(extrusion, injection molding, etc.) for its processing. In this regard, the development of new and
improvement of known technologies for the production of high-strength and high-modulus

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UHMWPE films and tapes are of special importance. At present, this problem is mainly solved
by using the gel-spinning method with subsequent orientation drawing [1]. The main
disadvantage of this method is the low solubility of the polymer, which determines the need for
large quantities of high-boiling solvents and the associated high costs for its regeneration. The
developed method of solid-phase processing of UHMWPE reactor powders in high-strength
films and tapes [2-4] certainly has a number of serious technological and economic advantages
in comparison with gel spinning. However, this method can be successfully used only for
processing of UHMWPE nascent reactor powders with a morphology close to that of single-
crystal mats [5].
It was established in [5-13] that the nascent reactor powders of the required quality can be
obtained on single-center post-metallocene catalysts, under mild conditions of polymerization
process (low concentrations of the catalysts, low temperature and pressure). In the overwhelming
majority of publications, phenoxyimine complexes of titanium (IV) are used as single-center
catalysts.
However, in [14] we showed the possibility of using more accessible titanium (IV)
diolate complexes (Compound A, Fig.1) in combination with aluminum alkyl chlorides and
organomagnesium compounds; the obtained UHMWPE powder was processed into orientated
film tapes with breaking strength over 2.3 GPa and elastic modulus over 150 GPa. However, the
geometry of 1,4-diolate ligands leading to the formation of unstable 7-membered metallocycles,
facilitated the formation of L3Ti2(OiPr)2 complexes (Compound B, Fig.1). It could be assumed
that the activation of such complexes by the organoaluminium compounds will lead to the
cleavage of ligands, which inevitably leads to the appearance of a set of catalytically active sites
and broadening of the MWD of polymers.
Despite the fact that 1,2-diols are able to form stable five-membered chelate rings, the
catalytic activity of such titanium complexes in olefin polymerization has been studied rather
poorly. The diolate complexes C and D (Fig. 1), activated with Et3Al2Cl3, catalyzed the
formation of low molecular weight PE [15]. It is known that pinacol derivatives form highly
stable titanium-containing Metal-Organic Framework (structure E, Fig. 1) [16], but their ability
to catalyze the polymerization of olefins has not been studied. With the increasing of steric
hindrance around hydroxyl groups, it becomes possible to obtain "individual" coordination
compounds (structures F and G in the crystalline state are dimers stabilized by O →Ti bonds)
[17-19].

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A
R=C6H5, C6F5;
C
B
D R=iPr, Et, Bu
R'=OiPr, OEt,OBu, Cl
X=Cl, OiPr;
Solv=iPrOH, thf
Complexes Active in the Polymerization of Ethylene
E
F
G
Fig. 1. Examples of Ti (IV) diolate complexes.
The present work aims to investigate the relationship between the structures of novel 5-
membered diolate titanium (IV) complexes and their activity in ethylene polymerization, and
mainly with their ability to catalyze the production of disentangled UHMWPE.
2. Results and discussion
2.1.Ligands and coordination compounds synthesis and structure.
It is known that the introduction of highly fluorinated fragments into the diol ligands
significantly increases their acidity. A larger steric hindrance, in comparison with non-
fluorinated analogs, as well as chemical inertness, in a number of cases makes it possible to
increase the stability of LTiX2 complexes. In the present work, we used fluorinated and non-
fluorinated 1,2-diols - commercially available pinacol and perfluoropinacol. Tetraphenylethane-
1,2-diol, 1,2-diphenyl-1,2-perfluorophenylethane-1,2-diol and tetrakis(pentafluorophenyl)
ethane-1,2-diol have been obtained by reductive dimerization of the corresponding carbonyl
compounds with zinc powder in THF/NH4Cl aq. [20].

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Ti(OiPr)4,
toluene
Zn, THF/NH4Cl aq
R=R'=Ph;
2a
2b
R=R'=Ph;
1a
1b
R=R'=C F ;
R=R'=C F ;
6
5
6
5
R=R'=Ph;
R=R'=C F ;
R=Ph, R'=C F
3c
6 5
3a
3d
3b
R=Ph, R'=C F
2c
2d
2e
6
5
R=Ph, R'=C F
1c
6
5
6
5
R=R'=CH ;
R=R'=CF
3e
R=CH ;
3
3
3
R=CF
0.5 eq. Ti(OiPr)4,
toluene
3
3f
Scheme 1. Synthesis of Ti(IV) diolate complexes 3a-3f.
Alkoxo-titanium complexes have been obtained by the interaction of toluene solutions of
ligands 2a-e with titanium (IV) tetraisopropoxide at room temperature. The resultant complexes
1
3a-f have been identified on the basis of H, 13C and 19F NMR spectra, IR spectroscopy and
elemental analysis.
The structures of the complexes 3d and 3e have been unambiguously established by X-
ray diffraction study and are shown in Fig. 2A and B respectively, along with the atomic
numbering schemes. The pertinent bond lengths and angles are given in Table S1-S2.
A
B
Fig. 2. A. Molecular structure of complex 3d (A) and 3e (B). 50% ellipsoids, hydrogen atoms are
omitted for clarity.
The both titanium complexes are the centrosymmetrical dimers and, in the crystal,
occupy the special positions on the inversion centers. The dimers include the central four-
membered Ti2O2-ring formed by the two µ-bridging isopropoxy (in the case of 3e) or

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deprotonated pinacol (in the case of 3d) ligands, with the Ti⋅⋅⋅Ti separation of 3.1218(12) and
3.265(2) , respectively. The geometry around each titanium atom is distorted square-pyramidal,
with the basal planes consisting of the O1, O2, O4 and O4A oxygen atoms for 3e and the O2,
O2A, O3 and O4 oxygen atoms for 3d. The metal centers are tilted from these planes in the
direction of the apical oxygen atoms O3 (in the case of 3e) and O1 (in the case of 3d). The
chelate five-membered cycles adopt the envelope conformations. As expected, the µ-bridging
Ti─O bond distances are significantly longer than the terminal ones (Table 1).
Crystal packing of 3d and 3e is stacking along the crystallographic b and a axis,
respectively (Figures S1 and S2). The molecules are arranged at van-der-Waals distances.
It is quite obvious that the dissociation of the Ti←O bond of these complexes during the
activation by organoaluminum compounds will result in the formation of monomer complexes
with a coordinatively unsaturated tetrahedral titanium (IV) atom and two terminal and easily
substituted isopropoxy groups. This, in accordance with modern concepts of the Ziegler catalysis
mechanism, is of fundamental importance for the manifestation of catalytic activity for olefin
polymerization.
2.2. Catalytic properties of Ti diolate complexes.
All complexes reported herein have been tested for their ability to catalyze the ethylene
polymerization. The polymerization was carried out under the same conditions such as
temperature, Al/Ti ratio, solvent and ethylene pressure. The most relevant results of ethylene
polymerization using pre-catalysts 3a-f are shown in Table 1. It was observed that complexes 3a-
f in the presence of Et2AlCl or Et3Al2Cl3 as co-catalyst have demonstrated rather low catalytic
activity and yielded only the trace amounts of the polyethylene. Introduction of
dibutylmagnesium to the catalytic systems containing aluminum alkyl chlorides leads to a
significant increase in activity (up to 3029 kg of PE mol-1h-1 atm-1, run 14). The obtained results
are consistent with the works [21-22], in which a mixture of AlR2Cl/MgR2 was proposed as
universal cocatalysts for Ziegler–Natta catalytic systems.
Table 1.
Ethylene Polymerization by complexes 3a-d a
Bulk
density,
g/cm3
c
Comp-
lex
Cocatalyst,
Al/Mg
Мv,
106
Tm
Deg.of
Crystald %
Run
Ab
°С
Et2AlCl/ MgBu2
300/100
Et3Al2Cl3/MgBu2
300/100
Et2AlCl/MgBu2
300/100
1.58
7.73
1.08
139/136
142/136
136/132
67.5/48.9
78.5/49.7
65.0/51.6
3a
3a
3b
2629
2057
2457
0.035
0.056
0.035
1
2
3

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300/100
Et2AlCl/ MgBu2
300/100
Et3Al2Cl3/ MgBu2
300/100
Et3Al2Cl3/MgBu2
4.86
1.34
4.67
140/133
137/135
140/135
78.1/49.3
78.6/64.6
76.5/44.7
3b
3c
3c
2800
2629
2314
0.076
0.040
0.064
4
5
6
Et2AlCl/ MgBu2
300/100
2629
2514
1829
1829
2029
2114
2286
3029
2914
2971
2571
0.046
0.051
0.031
0.042
0.066
0.084
0.035
0.060
0.049
0.053
0.059
2.42
5.63
2.94
5.18
1.31
3.20
2.92
6.71
1.66
3.34
1.59
138/134
141/135
139/136
141/136
138/134
140/135
139/135
142/136
138/133
140/135
135/130
64.1/44.9
76.3/46.6
75.3/48.2
74.7/41.9
67.2/52.3
68.7/45.0
72.5/45.9
75.4/46.6
68.4/52.8
75.1/47.2
61.4/41.1
7
8
3d
3d
Et3Al2Cl3/MgBu2
300/100
Et2AlCl/ MgBu2
300/100
9
3e
Et3Al2Cl3/MgBu2
300/100
10
11e
12e
13
14
15
16
17
3e
Et2AlCl/ MgBu2
300/100
3e
Et3Al2Cl3/MgBu2
300/100
3e
Et2AlCl/ MgBu2
300/100
3f
Et3Al2Cl3/
MgBu2 300/100
3f
Et2AlCl/ MgBu2
300/100
Ti(OiPr)4
Ti(OiPr)4
Ti(OiPr)4
Et3Al2Cl3/MgBu2
300/100
Et2AlCl/ MgBu2
200/100
a Polymerizations carried out in 100 mL of toluene with 5 10-6 mol of catalyst at a constant 0.7 atm ethylene pressure for 30 min,
temperature 30 oC.
b Activity, kg of PE mol-1h-1 atm-1.
c Melting points were determined by DSC, the values for the first and second heating runs are given
d. Degree of crystallinity was calculated by use of value ∆Hm100% = 288 J/g [23]; the values for the first and second heating runs
are given.
e amount of catalyst - 1 10-5 mol.
From Table 1 it is apparent that the structure of pre-catalyst, as well as the nature of
organoaluminum activator, does not have a significant effect on the activity of the complexes,
which, ceteris paribus, is in the range 1829-3029 kg of PE mol-1h-1 atm-1. Unexpectedly the
maximum catalytic activity in this series was shown not by systems based on dimeric complexes,
capable of dissociation upon activation by aluminum and magnesium organics, but by a system
based on a spiro-complex 3f with covalent Ti-O bonds. Using the example of pre-catalyst 3e it
was shown that an increase in the catalyst amount from 5·10-6 to 1·10-5 moles is accompanied by
a slight increase in activity and a marked decrease in the viscosity-average molecular weights of
the polymers (runs 9 vs. 11 and 10 vs. 12).

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For all studied catalyst precursors, the replacement of Et2AlCl with Et3Al2Cl3 leads to a
significant increase in the molecular weight of the polymer (Table 1, Figure 3). A similar trend
was observed for titanium complexes stabilized with 1,4-diol ligands [14].
Fig. 3. Molecular weight of the obtained UHMWPE samples versus the nature of activators.
The production of low molecular weight PE (639-1036 g mol-1) on 1,2-diolate titanium
complexes activated with Et3Al2Cl3 [15] clearly indicates a significant rate of chain transfer
process on the organoaluminum compounds. Obviously, the introduction of the
organomagnesium compound in the catalyst system significantly retards the process. The
observed increase in the molecular weight of PE with the use of Et3Al2Cl3 instead of Et2AlCl is
difficult to explain solely by the nature of the organoaluminum compounds. Thus, for example,
the molecular weight of PE synthesized on Cp2TiCl2/Et2AlCl was 15-30% higher than the values
obtained using the Cp2TiCl2/Et3Al2Cl3 system [24]. It is more likely that the reason for such a
significant increase in the molecular weight of UHMWPE is in the composition of the interaction
products of the binary activator {Et3Al2Cl3 +Bu2Mg}, which, for example, can be formed by
reactions 1-2:
3Et2AlCl + Bu2Mg = MgCl2 + 2AlEt2Bu + AlEt2Cl
1
2
3Et3Al2Cl3 + 2Bu2Mg = 2MgCl2 + 2AlEt2Bu + AlEtBu2 + Et2AlCl + 2EtAlCl2 +….
The above equations are conditional and do not have full experimental confirmation.
They do not take into account the differences in the reactivity of alkyl aluminum chlorides,
possible symmetrization processes, exchange reactions, etc., but the established fact of the
magnesium chloride formation when combining the activator components indicates a significant
increase in the content of aluminum alkyl chlorides of various nature in the reaction media and,
accordingly, the formation of a set of active sites.

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Apart from increasing the molecular weight, a replacement of Et2AlCl with Et3Al2Cl3
leads to a marked increase in the crystallinity degree and melting temperature of UHMWPE
samples at the first heating. During the second heating run, these values are leveled, which
indirectly indicates a high degree of disentanglement of nascent reactor powders.
2.1.Mechanical properties of synthesized UHMWPE
The processing of reactor powders of UHMWPE obtained on complexes 3a-f into
high-modulus oriented films was carried out by preparing monolithic samples under pressure
and shear deformation at an elevated temperature below polymer melting point with
subsequent uniaxial drawing [5]. Criteria for the quality of the resulting oriented film tapes
were: homogeneity of the resulting filament along the width and homogeneity of the samples
masses within one multiplicity at one length. For comparison, the mechanical properties of
film tapes drawn from the UHMWPE reactor powder obtained on the Ti(OiPr)4/Et3Al2Cl3
(run 16) are given in the table 2. As can be seen, the maximum drawing ratio in this case did
not exceed 20 at rather mediocre mechanical characteristics of the filaments.
Table 2.
Mechanical properties of UHMWPE oriented film tapes
E,
Catalytic system b
3a/ Et3Al2Cl3/MgBu2
3b/ Et3Al2Cl3/MgBu2
3c/ Et3Al2Cl3/MgBu2
3d/ Et3Al2Cl3/MgBu2
3e/ Et2AlCl/MgBu2
σ,
ε, e
%
Run a
Draw ratio
GPa
135
95
GPa
2.56
2.75
24
28
2.88
2.56
2.41
2.48
2
4
140
140
40
44
2.77
2.72
36
36
20
32
36
28
20
2.82
2.74
2.09
2.72
2.47
2.41
1.99
145
130
75
2.46
2.55
3.28
2.37
2.71
2.27
2.12
6
8
9
3e/ Et3Al2Cl3/MgBu2
3f/ Et2AlCl/MgBu2
10
13
14
16
140
120
105
105
3f/ Et3Al2Cl3/MgBu2
Ti(OiPr)4/Et3Al2Cl3/MgBu2
a Numbering corresponds to Table 1.
b Molar ratio [Ti]:[Al]:[Mg] = 1:300:100.

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Most of the reactor powders produced on catalytic systems with Et2AlCl proved to be
unsuitable for solid-phase processing, with the exception of the powders synthesized on
complexes 3e and 3f stabilized by perfluoropinacol (Table 2, runs 9 and 13).
Practically all of the rector powders synthesized using Et3Al2Cl2 have been
successfully processed into high-strength, high-modulus materials. Reactor powders obtained
in the present work allowed to achieve maximal drawing ratios (up to 44), among the samples
obtained on titanium complexes with OO-type ligands [14, 25-26].
As can be seen from Table 2, the best mechanical characteristics were demonstrated
by films obtained on complexes with fluorinated ligands. Among the complexes 3a-c
stabilized by the ligands with aromatic substituents, the maximum strength characteristics -
2.82 GPa was obtained on an "asymmetric" pre-catalyst 3c (elastic modulus 145 GPa at draw
ratio = 36, run 6). For the pre-catalysts 3d-f with aliphatic ligands, the positive effect of the
presence of fluorine manifests itself to a lesser degree. Interestingly, the mechanical
characteristics of the film from UHMWPE obtained on the spiro-complex 3f activated with
Et2AlCl surpassed the analog obtained from 3f/Et3Al2Cl2. The maximum achievable drawing
ratio of the film from the UHMWPE powder obtained on Ti(OiPr)4/Et3Al2Cl2 system did not
exceed 20. The mechanical characteristics of this film are also very mediocre.
It is well known [27] that drawability of UHMWPE highly depends on its supramolecular
structure. To examine the morphologies of these powders, SEM observations have been made
(Figure 4). All of these micrographs are of the same magnification for comparative purposes. As
can be seen from the scanning electron micrographs at low magnification, the polymer particles
have the irregular shape and porous structure, that determines the low bulk density (0.031-0.084
g/cm3) of the obtained samples.

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A
B
C
D

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E
F
J
H
Fig. 4. Scanning electron micrographs of a series of nascent reactor powders, prepared on
3a/Et2AlCl (A-B), 3a/Et3Al2Cl3 (C-D), 3c/Et2AlCl (E-F), 3c/Et3Al2Cl3 (J-H).
The high magnification micrographs clearly show that all catalytic systems, regardless of
the nature of the organoaluminum activator, were found to produce polymers with nodular type
microstructures. The main morphological difference between UHMWPE powders obtained on
3a-e /Et3Al2Cl3, and samples obtained on 3a-e/Et2AlCl, and unsuitable for orientational drawing
is the irregular shape of microparticles - nodes. It is known that polymeric powders having
irregular, spongy particles compacted better than those consisting of spherical, dense particles
[28].

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In general, the morphology of the polymers obtained using various activators (Et2AlCl or
Et3Al2Cl3) differs insignificantly. Obviously, in this case, the factors determining the possibility
of solid-phase processing are significantly higher values of Mv and crystallinity of the polymers
obtained with Et3Al2Cl3.
3. Conclusion
•
•
•
In summary, a series of titanium (IV) complexes bearing 1,2-diolate ligands have been
synthesized in high yields. Structures of complexes 3d-e have been established by X-ray
diffraction.
All complexes in the presence of a binary co-catalysts {3Et2AlCl + Bu2Mg} or
{1.5Et3Al2Cl3 + Bu2Mg} exhibited moderate to high activities towards ethylene
polymerization (1829-3029 kg of PE mol-1h-1 atm-1).
It should be noted that the spiro-complex 3f unexpectedly showed high catalytic activity,
despite its activation, in our opinion, is more difficult compared with the complexes
having the composition LTi(OiPr)2.
•
•
All investigated pre-catalysts produced ultra-high-molecular-weight polyethylene
(viscosity-average molecular weights were in the range 1.1-7.7 106).
The complexes activated with Et3Al2Cl3 produce polymers with significantly higher
values of Mv, crystallinity and melting point on first heating run. This may be due to
differences in the composition of the reaction products {3Et2AlCl + Bu2Mg} or
{1.5Et3Al2Cl3 + Bu2Mg}.
•
•
•
All UHMWPE reactor powders obtained with Et3Al2Cl3 were processed into oriented
films with a strength of 2.0 - 2.8 GPa and an elasticity coefficient up to 145 GPa.
The best mechanical properties were exhibited by films obtained on complexes with
polyfluorinated ligands;
The properties of the produced films, and especially the drawing ratios, are superior to
materials previously obtained on titanium complexes with 1,4-diol ligands.
4. Experimental section
All manipulations with air-sensitive materials were performed with rigorous exclusion of
oxygen and moisture in oven-dried Schlenk glassware on a dual manifold Schlenk line,
interfaced to a high-vacuum line. Argon and ethylene of special-purity grade (Linde gas) were
dried by purging through a Super Clean™ Gas Filters.
NMR spectra were recorded on Bruker AMX-400 instrument. Deuterated solvents
(CDCl3, THF-d8) were degassed by freeze-pump-thaw vacuum cycles and stored over 3 Å

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molecular sieves. Chemical shifts are reported in ppm vs. SiMe4 and were determined by
reference to the residual solvent peaks. All coupling constants are given in Hertz. Air-sensitive
NMR spectra were taken in J. Young tubes with Teflon valve plugs. IR spectra were recorded on
a Magna-IR 750 spectrophotometer. Elemental analysis was performed by the microanalytical
laboratory at A. N. Nesmeyanov Institute of Organoelement Compounds.
Toluene was distilled over Na/benzophenone ketyl and the water content was periodically
controlled by Karl-Fischer coulometry by using a Methrom 756 KF apparatus. Diethylaluminum
chloride, ethylaluminum sesquichloride and di-n-butylmagnesium (Aldrich) were used as 1.0 M
solution in heptane. Decafluorobenzophenone and perfluoropinacol were obtained from SIA
"P&M-Invest" Ltd., Moscow
4.1. Ligands 3a-c were obtained using general procedure [20].
Zn powder (4 mmol, 0.26 g) and carbonyl compound (2 mmol) were slurried in 3 cm3
saturated aqueous NH4Cl and 5 cm3 THF. The mixture was stirred at room temperature. The
temperature rose, and the Zn powder had disappeared. The solvents were evaporated to dryness,
and the product was extracted with diethyl ether. The etheral layer was separated and evaporated
to dryness to afford the pure pinacol.
4.2. (1,1,2,2-Tetraphenylethane-1,2-diyloxy)bis(isopropoxy)titanium (3a)
Compound 3a (3.66 g, 10 mmol) and toluene (20 mL) were placed into a Schlenk tube equipped
with a magnetic stirrer under argon atmosphere, followed by the addition of Ti(OiPr)4 (3.0 ml,
10 mmol) at r.t. The resulting suspension was heated until all solids dissolved. After 10 h at r. t.
the formed crystals were collected by filtration and dried in vacuo. Yield 8.7 g (65.7 %).
Calculated (%) for C65H72O8Ti2 (1076): C, 72.49; H, 6.74; Ti, 8.89. Found (%): C, 72.41; H,
1
6.68; Ti, 8.83. H NMR (CDC13): δ = 1.22-1.24 (d, J = 6.1 Hz, 24 H, CH3), 4.04 (m, 4H, СH),
6.80-7.34 (m, 40H, Ar). l3C NMR (101 MHz, CDCl3) δ 144.25, 132.83, 132.44, 131.81, 130.29,
130.07, 129.66, 129.21, 128.91, 128.64, 128.37, 128.28, 127.24, 127.12, 126.90, 126.72, 126.55,
126.20, 125.78, 125.50, 83.04, 80.50, 64.51, 25.86, 25.73, 25.58, 25.30, 22.90. FT-IR (KBr):
662, 554 cm-1 ν(Ti-O).
Using this general procedure, the following compound have been isolated:
4.3. (1,1,2,2-tetrakis(pentafluorophenyl)-ethane-1,2-diyloxy)bis(isopropoxy)titanium (3b)
Yield 54.9 %. Calculated (%) for C65H32 F40O8Ti2 (1760): C, 43.45; H, 1.80; Ti, 5.33. Found
(%): C, 43.38; H, 1.72; Ti, 5.26. 1H NMR (CDC13): δ =1.26-1.27 (d, J = 6.1 Hz, 24 H, CH3),
4.51 (m, 4H, СH). l9F NMR (300 MHz, CDCl3) δ 140.78, 148.43, 160.22. FT-IR (KBr): 623, 552
cm-1 ν(Ti-O).

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4.4. 1,2-bis(pentafluorophenyl)-1,2-diphenylethane-1,2-diyloxy)bis(isopropoxy)titanium
(3c) Yield 42.9 %. Calculated (%) for C65H52 F20O8Ti2 (1436): C, 54.34; H, 3.65; Ti, 6.66. Found
(%): C, 54.27; H, 3.58; Ti, 6.49. 1H NMR (CDC13): δ =1.77 (m, 24 H, CH3), 3.65 (m, 4H, СH),
7.13-7.27 (m, 20H, Ar). FT-IR (KBr): 613, 552 cm-1 ν(Ti-O).
4.5. (2,3-dimethyl-butane-2,3-diyloxy)bis(isopropoxy)titanium (3d). Yield 61.5 %.
Calculated (%) for C25H56 O8Ti2 (580): C, 51.73; H, 9.72; Ti, 16.49. Found (%): C, 51.68; H,
1
9.69; Ti, 16.45. H NMR (CDC13): δ =1.13-1.16 (m, 48 H, CH3), 3.93 (m, 4H, СH). FT-IR
(KBr): 613, 552 cm-1 ν(Ti-O).
4.6. (1,1,1,4,4,4-hexafluoro-2,3-bis(trifluoromethyl)-butane-2,3-diyloxy)-bis(isopropoxy)-
titanium (3e). Yield 62.9 %. Calculated (%) for C25H56 F24O8Ti2 (1012): C, 29.66; H, 3.19; Ti,
9.46. Found (%): C, 29.51; H, 3.11; Ti, 9.39. 1H NMR (CDC13): δ =1.23-1.29 (m, 24 H, CH3),
4.43 (m, 2H, СH), 4.81 (m, 2H, CH). l9F NMR (300 MHz, CDCl3) δ 71.19, 71.53. FT-IR (KBr):
666, 575 cm-1 ν(Ti-O).
4.7. Bis-(1,1,1,4,4,4-hexafluoro-2,3-bis(trifluoromethyl)-butane-2,3-diyloxy)
titanium
.
(3f). Yield 48.3 %. Calculated (%) for C12F24O4Ti C3H8O (772): C, 23.34; H, 1.04; Ti, 6.20.
Found (%): C, 23.27; H, 0.91; Ti, 6.17. 1H NMR (CDC13): δ =1.35 (b-c, 6 H, CH3), 4.80 (m, 1H,
СH). l9F NMR (300 MHz, CDCl3) δ 70.73, 71.53. FT-IR (KBr): 666, 575 cm-1 ν(Ti-O).
4.8. X-ray crystal structure determination.
The single-crystal X-ray diffraction data for 3e and 3d were collected on the ‘Belok’
beamline of the Kurchatov Synchrotron Radiation Source (National Research Center ‘Kurchatov
Institute’, Moscow, Russian Federation) using a Rayonix SX165 CCD detector at λ = 0.80246 Å.
A total of 720 images for two different orientations in the case of each crystal were collected
using an oscillation range of 1.0° and
ϕ scanning mode. The data were indexed and integrated
using the utility iMOSFLM from the CCP4 program suite [29] and then scaled and corrected for
absorption using the Scala program [30]. For details, see Table 2. The structures were
determined by direct methods and refined by full-matrix least square technique on F2 in
anisotropic approximation for non-hydrogen atoms. In the crystal of 2, two different isomers are
arranged in the same positions with the occupancies of 0.75:0.25. The hydrogen atoms in 3e and
3d were placed in calculated positions and refined within the riding model with fixed isotropic
displacement parameters [Uiso(H) = 1.5Ueq(C) for the methyl groups and 1.2Ueq(C) for the other
groups]. All calculations were carried out using the SHELXTL program suite [31].
Crystallographic data for 3e and 3d have been deposited with the Cambridge Crystallographic
Data Center, CCDC 1855966 and CCDC 1855965. The supplementary crystallographic data can
be obtained free of charge from the Cambridge Crystallographic Data Centre via

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www.ccdc.cam.ac.uk/data_request/cif.
4.9. Polymerization of ethylene
The ethylene polymerization was performed in a 300-ml reactor (Parr Instrument Co.) equipped
with a magnetic stirrer and inlets for loading components of catalytic systems and ethylene at a
total pressure of ethylene and toluene vapours of 0.7 atm. Toluene (100 ml) and the necessary
amount of a co-catalyst (Et2AlCl/Bu2Mg or Et3Al2Cl3/Bu2Mg) were loaded in the reactor. The
reactor was heated to a specified temperature, and the reaction mixture was saturated with
ethylene. Polymerization was started by the addition of pre-catalyst to the reaction mixture. The
pressure of ethylene was maintained constant during polymerization. Polymerization was
stopped through the addition of 10% HCl solution in ethanol to the reactor. The polymer was
filtered off, washed several times with water-ethanol mixture, and dried under vacuum at 50-60
ºC until a constant weight was achieved.
4.10. Polymer evaluation methods
DSC was performed by a differential scanning calorimeter DSC-822e (Mettler-Toledo,
Switzerland) at a heating rate 10 ºC/min in air.
Viscosity-average molecular weight of synthesized UHMWPE samples was calculated with
the Mark-Houwink equation: Mv = 5.37·104 [η]1.37 [1], where: Mv = viscosity-average
molecular weight (g/mol); [η] = intrinsic viscosity in decalin at 135°C (dl/g); [η] = (2ηsp -
2lnηr )1/2/0.056 (ηsp - specific viscosity decalin at 135°C; ηr - relative viscosity in decalin at
135°C; ηr = ηsp +1.
The mechanical characteristics of the oriented materials prepared with the synthesized
polymers were evaluated on the oriented tapes obtained by a solid state processing of UHMWPE
nascent reactor powders. The uniform over the entire length monolithic tapes (100 mm in
thickness and 10 mm in width) were formed at a pressure and shear deformation below the
polymer melting point (124-126 ºC). The tapes were subjected to uniaxial drawing while using a
Spinline Daca equipment. The drawing temperature was set 4 ºC below the polymer melting
point. The mechanical characteristics of the tapes were measured with a Hounsfield H1KS
machine at the gauge length of the tested samples 120 mm with 2 mm/min initial deformation
rate. The reported values were the average of at least 8 samples.
Acknowledgments
This work was financially supported by the Russian Science Foundation (Project No 16-13-
10502). Synchrotron radiation-based single-crystal X-ray diffraction measurements were
performed at the unique scientific facility Kurchatov Synchrotron Radiation Source supported

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by the Ministry of Education and Science of the Russian Federation (project code
RFMEFI61917X0007) and the RUDN University Program “5-100”.
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Highlights
Novel titanium complexes bearing 1,2-diolate ligands were synthesized and fully
characterized.
Complexes in the presence of {Et2AlCl+Bu2Mg} produced high molecular weight
polyethylene
The replacement of Et2AlCl with Et3Al2Cl3 leads to a significant increase in Mv (up to 7.7
106) and the crystallinity of UHMWPE samples.
Polymers are suitable for the solvent-free formation of high-strength (up 2.8 GPa) and high-
modulus (up to 145 GPa) oriented film tapes.