Coordination compounds of titanium (IV) and 2-hydroxymethyl-phenol derivatives: Their synthesis, structure and catalytic activity in ethylene and 1-hexene polymerization

Article abstract of DOI:10.1016/j.jorganchem.2015.08.017

A series of titanium complexes LTiCl₂·(ⁱPrOH)₂12-18 and heterobimetallic complex L₂Ti·ⁱPrOLi·THF 19 bearing saligenin-type [O,O]^2- ligands 6-11 were synthesized in high yields from Cl₂

Full text of DOI:10.1016/j.jorganchem.2015.08.017

Journal of Organometallic Chemistry 797 (2015) 159e164
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Coordination compounds of titanium (IV) and 2-hydroxymethyl-
phenol derivatives: Their synthesis, structure and catalytic activity in
ethylene and 1-hexene polymerization
, b,
Vladislav A. Tuskaev a *, Svetlana Ch Gagieva a, Michail V. Solov'ev a,
,
Dmitrii A. Kurmaev a b, Nikolay A. Kolosov a, Ivan V. Fedyanin b, Boris M. Bulychev a
a Department of Chemistry, M. V. Lomonosov Moscow State University, 1 Leninskie Gory, 119991 Moscow, Russian Federation
b A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, ul. Vavilova 28, 119991 Moscow, Russian Federation
a r t i c l e i n f o
a b s t r a c t
A series of titanium complexes LTiCl2$(iPrOH)2 12-18 and heterobimetallic complex L2Ti$iPrOLi$THF 19
bearing saligenin-type [O,O]2- ligands 6-11 were synthesized in high yields from Cl2Ti(OiPr)2 or
LiTi(OiPr)5. X-ray structure analyses for 15 and 19 revealed that these complexes adopt a distorted oc-
tahedron or distorted tetragonal pyramid geometry. When activated by binary activator
{3Et2AlCl þ Bu2Mg}, complexes 12-19 exhibited moderate to high activities toward ethylene and 1-
hexene polymerization, giving high molecular weight polymers with broad molecular weight distribu-
tions. The results of this study show the unique ability of Li and Mg chlorides to improve the catalytic
ability of post-metallocene pre-catalysts.
Article history:
Received 11 July 2015
Received in revised form
19 August 2015
Accepted 20 August 2015
Available online 29 August 2015
Keywords:
Polymerization
Titanium
© 2015 Published by Elsevier B.V.
Magnesium
Polyolefin
ZieglereNatta
1. Introduction
2. Results and discussion
Achievements inpost-metallocene catalysis weresummarized in
several recent reviews [1e5]. It is generally recognized that the most
efficient post-metallocene catalysts are the group 4 metals coordi-
nation compounds stabilized by phenoxide ligands. Usually, those
ligands contain additional donor atoms, such as imine or amine ni-
trogen [6] (O,N ligands), or sulfur [7] (O,S ligands). There are sub-
stantially fewer examples of metal complexes with OO-type ligands
used as precatalysts for the olefin polymerization catalysis. And
among those saligenin-based complexes (where ligand structure
contain both phenol and alcohol hydroxyls) are indeed unique [8,9].
The purpose of present work was to synthesize the Ti (IV)
complexes with a variety of saligenin ligands, and to evaluate their
structure and catalytic activity in ethylene and 1-hexene poly-
merization reactions upon activation by different co-catalysts, as
well as the impact of non-transition metals salts (Li, Mg) in catalytic
activity.
2.1. Ligands and complexes synthesis
When choosing the saligenin benzylic carbon substituents, we
have originally favored the fluorine-containing moieties. We ex-
pected them to be similar to the phenoxyimines [6,10,11] and
TADDOLs complexes [12e14] where introduction of fluorine moiety
in ligand structure results in increase of Ti atom acidity and thus
improving the catalytic activity of resulting complex.
Ligands 6-9 were synthesized by reacting the 1-(3,5-di-tert-
butyl-2-hydroxyphenyl)-2,2,2-trifluoroethanone with respective
metal-organic derivatives (Scheme 1). Ligands without fluorine
moieties 10-11 were synthesized by lithiation of 2,4-di-tert-butyl-
6-bromo-phenol, with subsequent treatment of lithium derivative
with respective carbonyl compound.
Titanium complexes 12-18 were synthesized by direct interac-
tion of ligands 6-11 with one equivalent of TiCl2(O-iPr)2 in toluene
(Scheme 2, path a). The X-ray structure of representative complex
15 is presented on Fig. 1. In 15 titanium atom has a distorted octa-
hedron coordination formed by chlorine atoms, oxygens of original
ligand and isopropanol oxygens of leaving isopropoxy groups.
* Corresponding author. Department of Chemistry, M. V. Lomonosov Moscow
State University, 1 Leninskie Gory, 119991 Moscow, Russian Federation.
E-mail address: tuskaev@yandex.ru (V.A. Tuskaev).
http://dx.doi.org/10.1016/j.jorganchem.2015.08.017
0022-328X/© 2015 Published by Elsevier B.V.

160
V.A. Tuskaev et al. / Journal of Organometallic Chemistry 797 (2015) 159e164
possibility of such scenario we have studied the interaction of
saligenin-type ligand 6-(1,1,1,3,3,3-hexofluoro-2-hydroxypropane-
2-yl)-4,6-di-tert-butylphenol with LiTi(OiPr)5. The structure of
synthesized heterometallic complex L2Ti٠iPrOLi٠TGF (19) was
resolved by X-ray crystallography (Fig. 1, on the right).
b
a
Compound 19 co-crystallizes with a solvate methylene chloride
molecule. Ti atom coordination polyhedron is a distorted tetragonal
pyramid, where foundation is formed by ligands' oxygens, and the
top is formed by an isopropyl fragment oxygen. Lithium coordina-
tion polyhedron is a significantly distorted tetragonal pyramid,
where foundation is formed by alcohol oxygens O(2) and O(4) as
well as fluorine atoms of trifluoromethyl groups F(1) and F(7), and
the top is formed by O(1T) - a coordinated tetrahydrofuran oxygen.
Considering the synthetic method, complex 19 structure and
composition, serve as a proof of secondary complexation resulting
in a molecular heterometallic complex.
4
6
5
c
d
7 R = Me;
8 R = Ph;
9 R = C6F5
10 R = R' = Me
11 R = R' = Ph
2.2. Catalytic activity and polymer properties
a BuLi, CF3CO2Me; b NaBH4, MeOH; c RLi or RMgHal; d BuLi, R2CO
Scheme 1. Synthesis of ligands 6-11.
Catalytic properties of synthesized compounds in the reaction of
ethylene and 1-hexene polymerization are summarized in Tables 1
and 2. All compounds listed in Table 1 cannot be activated by such
common co-catalysts as methylalumoxide, trimethylaluminum or
diethylalumochloride (MAO, Me3Al or Et2AlCl, ratio of Ti/
Al ꢀ 1:500). However, they demonstrate moderate activity in
presence of {3Et2AlCl/MgBu2} binary co-catalyst [18,19].
For example, complex 3 containing two CF3 groups [9], dem-
onstrates the highest catalytic activity at [Al]/[Ti] ratio equal to 500
(Table 1, runs 1e2). Substitution of one CF3 group for hydrogen,
methyl, phenyl or pentafluorophenyl groups (compounds 12, 13,14,
15) leads to the notable increase of catalytic activity that does not
change significantly upon the decrease of [Al]/[Ti] ratio to 300.
The increase of catalytic activity in complexes with a single CF3
group compared to 3 was unexpected, as we anticipated a contrary
effect. Even more surprising was the high catalytic activity dis-
played by complexes lacking the CF3 groups altogether. Complex 16
containing two phenyl moieties in benzyl position has catalytic
activity that is twice of that for the 3 (Table 1, runs 1 and 13). This
difference decreases upon Al/Ti ratio increase to about 500 (Table 1,
run 16); and at ratio equal to 1000, the overall system catalytic
activity is notably decreased. The kinetics of ethylene catalytic
polymerization in presence of this catalyst is stable and the whole
system is reasonably thermostable. It is active at both 50 and 80 ꢁС,
albeit the increase of temperature results in 2 fold decrease of
catalytic activity and increase of the polydispersity index (runs 14
and 15).
Scheme 2. Synthesis of Ti (IV) complexes with saligenines.
In our previous reports [9,12,13,15e17] we have associated a
relatively high catalytic activity of OO- or ONO-type ligands Ti
complexes to the Li or Mg compounds involved in formation of
secondary complexes through ligands oxygens. To evaluate the
The most active compounds of the series were 17 with two
methyl groups in benzyl position and 18 that is based on 2,4-di-
Fig. 1. General view of 15 (on the left; only the major component of dis-ordered molecule is shown) and 19 (on the right) in thermal ellipsoid representation (p ¼ 50%). Hydrogen
atoms except those of coordinated isopropyl moieties are omitted for clarity.

V.A. Tuskaev et al. / Journal of Organometallic Chemistry 797 (2015) 159e164
161
Table 1
Ethylene Polymerization by LTiCl2*(iPrOH)2-(Et2AlCl:Bu2Mg) Catalyst Systems.a
Run
Pre-catalyst
[Al]/[Ti]
Weight of PE, g
Activityb
Tgc, (ꢁC)
Mw
Mn
Mw/Mn
1
2
3
4
5
6
7
8
3
3
300
500
100
200
300
500
300
500
300
500
300
500
300
300
300
500
1000
300
500
300
500
300
500
2.3
3.7
0
1315
2140
142.7
144.8
1.21 ꢃ 106
2.11 ꢃ 105
5.73
Ins. in TCB
3d
3e
0
12
12
13
13
14
14
15
15
16
16f
16g
16
16
17
17
18
18
19
19
4.9
5.0
4.5
4.9
2.9
4.1
4.6
4.6
4.4
1.9
2.1
4.5
3.7
3.9
5.7
4.7
5.2
0.4
1.8
2800
2850
2570
2800
1660
2340
2630
2630
2515
1115
1230
2570
2115
2170
3170
2690
2970
230
145.7
141.4
147.0
140.0
142.0
146.9
140.0
142.0
146.2
141.7
142.5
144.2
Ins. in TCB
1.05 ꢃ 106
Ins. in TCB
1.66 ꢃ 105
7.89 ꢃ 104
6.32
8.08
9
6.39 ꢃ 105
Ins. in TCB
9.40 ꢃ 105
0.82 ꢃ 106
Ins. in TCB
1.28 ꢃ 106
1.39 ꢃ 106
Ins. in TCB
4.02 ꢃ 105
1.23 ꢃ 106
1.25 ꢃ 106
1.10 ꢃ 106
0.91 ꢃ 106
10
11
12
13
14
15
16
17
18
19
20
21
22
23
1.57 ꢃ 105
1.21 ꢃ 105
5.99
6.78
1.99 ꢃ 105
1.21 ꢃ 105
6.45
11.49
7.30 ꢃ 104
4.90 ꢃ 105
1.84 ꢃ 105
1.42 ꢃ 105
1.10 ꢃ 105
5.48
2.51
6.79
7.75
8.10
141.5
143.0
139.1
140.4
142.0
140.3
1030
1.27 ꢃ 106
1.68 ꢃ 105
7.56
a
Polymerizations carried out in 50 mL of toluene with 5
Kg of PE (mol of Ti atm)ꢂ1 hꢂ1
Melting temperatures determined by DSC at second heating of PE samples.
[Et2AlCl]/[Bu2Mg] ¼ 1:1.
[Et2AlCl]/[Bu2Mg] ¼ 2:1.
Temperature 50 ꢁC.
Temperature 80 ꢁC.
m
mol of catalyst at a constant 0.7 atm ethylene pressure for 30 min, temperature 30 ꢁC, [Et2AlCl]/[Bu2Mg] ¼ 3:1.
b
c
d
e
f
.
g
tert-butyl-saligenin. In terms of catalytic activity, either of them
surpasses the prototype compound 3. It is apparent that for this
series of post-metallocene complexes, neither the bulk of a benzyl
atom substituent nor its acceptor capacity impact the catalytic ac-
tivity of the resulting system.
Mixing complex 12 with preformed MgCl2 (Bu2Mg þ HCl)
regardless of the origin of the latter does not improve the system
activity. It appears that catalytic activity of the system increases
only when all components are formed simultaneously in statu
nascendi.
Heterometallic complex 19 demonstrates only the traces of ac-
tivity at [Al]/[Ti] ¼ 300. However, once the activation concentration
reaches 500 equivalents, activity of 19 increases about 4.5 times,
reaching 1030 kg of PE (mol of Ti atm)ꢂ1 hꢂ1. It is possible, that 19
demonstrates such mediocre activity due to two of it bulky bidental
ligands that hinder ethylene molecule binding to the catalytic
center. Unlike 19; compounds 3, 12-18 have octahedral central
atom surrounding - they are coordination saturated, but this
saturation is achieved through binding of two isopropanol mole-
cules. Those molecules can be relatively easily removed from the
coordination environment when the complex is treated with
alumo- or magnesium-organic compounds.
The polyethylene samples obtained in the above experiments
have a high molecular mass as most of them insoluble in tri-
chlorobenzene at 135 ꢁC. The IR spectra of those samples are
lacking the 1378 cmꢂ1 band attributed to the deformational vi-
brations of methyl groups, which means lack of chain branching
[20]. Respectively, all samples demonstrate high melting temper-
atures (139e147ꢁС).
The activities of studied catalysts in reaction of 1-hexene poly-
merization are generally substantially slower than the ones in
ethylene reaction. For that reason for activation we have used the
most effective co-catalyst - {3Et2AlCl þ MgBu2}. The results of these
studies are summarized in Table 2. As evident from Table 2 data, the
Table 2
1-Hexene polymerization by LTiCl2$(iPrOH)2-(3Et2AlCl/Bu2Mg) Catalyst Systems.a
Run
Pre-catalyst
[Al]/[Ti]
Conversion, (%)
Degree of isotacticity (mmmm) %b (mm, mr, rr) [21,22]
Mwc
Mnc
Mw/Mn
1
2
3
4
5
6
7
8
3
3
300
500
300
300
300
300
300
300
500
300
300
300
68
100
96
89
82
95
19
74
60
61 (0.76, 0.11, 0.13)
54 (0.65, 0.12, 0.23)
74 (0.83, 0.14, 0.03)
28 (0.56, 0.12, 0.28)
36 (0.53, 0.18, 0.29)
75 (0.84, 0.12, 0.05)
31 (0.53, 0.22, 0.25)
52 (0.60, 0.13, 0.27)
45 (0.55, 0.11, 0.34)
64 (0.71, 0.10, 0.19)
70 (0.78, 0.10, 0.12)
6.57 ꢃ 105
5.94 ꢃ 105
8.20 ꢃ 105
5.82 ꢃ 105
4.54 ꢃ 105
6.98 ꢃ 105
5.23 ꢃ 105
5.72 ꢃ 105
4.84 ꢃ 105
7.20 ꢃ 105
4.90 ꢃ 105
9.97 ꢃ 104
7.25 ꢃ 104
9.8 ꢃ 104
6.6
8.2
8.4
6.1
6.5
5.2
7.7
8.2
6.7
8.1
7.3
12
13
14
15
16
16
16
17
18
19
9.54 ꢃ 104
6.99 ꢃ 104
1.35 ꢃ 104
6.82 ꢃ 104
6.94 ꢃ 104
7.20 ꢃ 104
8.91 ꢃ 104
6.70 ꢃ 104
9
10
11
12
98
96
Traces
a
Polymerizations carried out in 2 mL of toluene, 6 ml of 1-hexene with 5
Determined by 13C NMR [21,22].
Determined from GPC in 1,2,4-trichlorobenzene using narrow polystyrene standards.
m
mol of catalyst for 24 h, temperature 5 ꢁC, [Et2AlCl]/[Bu2Mg] ¼ 3:1.
b
c

162
V.A. Tuskaev et al. / Journal of Organometallic Chemistry 797 (2015) 159e164
increase of [Al]/[Til] ratio with 3 increases the degree of monomer
conversion, that reaches 100% at 500 equivalents. However, this
change also causes the growth of polymer chain errors, resulting in
a decrease of isotacticity from 61% (mm - 0.76) (at 300 equivalents)
to about 54% (mm - 0.65). Since in case of 1-hexene resulting
polymer stereoregularity is a more essential parameter, the rest of
the experiments were carried out with Al/Ti ratio of 300.
Comparison of the results for 3 and 13 demonstrates that sub-
stitution of CF3 for methyl one results in significant decrease of
isotacticity. Compounds 14 and 15 that contain phenyl and per-
fluorophenyl substituents demonstrate good degree of conversion,
but significant stereospecificity can only be achieved with per-
fluorophenyl moiety (15, run 6). Compound 16 lacking the per-
fluorophenyl moiety has demonstrated very modest results in 1-
hexene polymerization. Thus, the most efficient catalyst was 15,
which demonstrated the degree of 1-hexene conversion of 95% and
high level of isotacticity (75%, mm - 0.84). It should be noted as well
that all investigated co-catalysts form multi-center systems which
is evident from the PDI values of resulting polyhexene samples.
Overall, there are no observed similarities between the poly-
merization processes for ethylene and 1-hexene in presence of
above catalysts.
Dichlorodiisopropoxytitanium and LiTi(O-i-Pr)5 were prepared
following literature procedures [23,24]. Ligand 11, 2,4-di-tert-butyl-
6-(hydroxydiphenyl-methyl)phenol, was synthesized as described
[25], its 1H and 13C NMR spectra were found to match the published
data.
NMR spectra were recorded on Bruker AMX-400 instrument.
Deuterated solvents (toluene-d8, CD2Cl2, CDCl3) were degassed by
freezeethawevacuum cycles and stored over 3 Å 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.
IR spectra were recorded on a Magna-IR 750 spectrophotometer.
Elemental analysis was performed by the microanalytical labora-
tory at A. N. Nesmeyanov Institute of Organoelement Compounds.
Gel permeation chromatography (GPC) of polymer samples was
carried out in 1,2,4-trichlorobenzene at 135 ꢁC on a Waters GPCV-
2000 chromatograph with the use of a PLgel 5 mm MIXED-C col-
umn. Molecular masses were estimated using the universal cali-
bration curve plotted relative to polystyrene standards.
The thermogravimetric analysis of samples was performed on a
NETZSCHSTA-Jupiter449 C instrument. Measurements were carried
out in a flow of argon (100 ml/min) in the temperature range
40e300 ꢁC. The heating rate was 5 ꢁC/min.
3. Conclusions
4.1. 2,4-Di-tert-buthyl-6-(2,2,2-trifluoro-1-hydroxyethyl)-phenol
In summary, a series of titanium complexes (12-18) and heter-
obimetallic (TieLi) complex 19 bearing saligenin-type [O,O]2ꢂ li-
gands (6-11) were synthesized in high yields from Cl2Ti(OiPr)2 or
LiTi(OiPr)5 with corresponding ligands in toluene. The X-ray solid
state diffraction study of complexes 15 and 19 was presented. Pre-
catalysts 12-19 are completely inactive in presence of MAO, Me3Al
or Et2AlCl. When activated by binary activator {3Et2AlCl þ Bu2Mg},
these complexes exhibited moderate to high activities toward
ethylene and 1-hexene polymerization, giving high molecular
weight polymers with broad molecular weight distributions. We
speculate that observed ability of magnesium chloride (which ap-
pears in the catalytic system as the result of the interaction of
MgBu2 with 2AlEt2Cl) to promote the catalytic process is due to the
products of secondary coordination.
Introducing fluorine-containing substituents in benzyl-position
of ligands wasn't resulted in significant change on catalytic activ-
ities. No notable effect of the steric and electronic parameters of
substituents in benzyl-position on the polymerization behavior
was revealed. Further modification of these systems to enhance
their catalytic performance is underway and will be reported in due
course.
(6)
An excess of NaBH4 was added to a stirred solution of 2.2 g
(7.2 mmol) of 5 in 10 mL of methanol, after which the reaction was
monitored by TLC. Upon completion of the reaction, water was
added and the product was extracted by methylene chloride. The
combined organic phase was washed with water, and dried over
MgSO4, after which the solvent was removed under reduced
pressure. The crude product was recrystallized from toluene -
hexane to give 1.62 g (73%) of a white solid. Anal. Calcd for
C
16H23F3O2 (304.35): C, 63.14; H, 7.62; F 18.73. Found: C, 62.98; H,
7.56; F 18.61. 1H NMR (400 MHz, CDCl3,
): 7.52 (1H, s), 7.05 (1H, s),
5.21 (2H, q, 7.2 Hz), 3.25 (1H, br), 1.44 (9H, s), 1.33 (9H, s). 19F NMR
(400 MHz, CDCl3,
): - 78.32 (d, 7.6 Hz). 13C NMR (400 MHz, CDCl3,
): 152.54, 141.62, 136.88, 125.98, 124.50, 116.78, 35.12, 34.33, 31.27,
29.56.
d
d
d
4.2. 2,4-Di-tert-butyl-6-(1,1,1-trifluoro-2-hydroxy-propan-2-yl)-
phenol (7)
To a solution of MeMgI (10 mmol) in Et2O, prepared from
magnesium (0.29 g, 12 mmol) and MeI (0.62 ml,10 mmol) was
added dropwise an ethereal solution of 1-(2,4-di-tert-buthyl-
phenyl)-2,2,2-trifluoromethylethanone-1 (1.08 g; 3.6 mmol) at 0ꢁС.
The reaction mixture allowed to slowly warm to room temperature,
stirred overnight, quenched with HCl (1 M, 5 ml) and then and the
product was extracted by diethyl ether. The combined organic
phase was dried over Na2SO4, and the solvent was removed under
reduced pressure. Recrystallization of the crude product from
hexane gave 0.8 g (70%) of a colorless solid. 1H NMR (CDCl3, 25 ꢁC)
1.28 (s, 9Н), 1.42 (s, 9Н), 1.90 (s, 3Н), 3.09 (s, 1Н) 7.00e7.04 (m, 1Н),
7.34 (d, 1Н, J ¼ 2.3 Hz) 8.56 (s, 1Н). 19F NMR (CDCl3, 25 ꢁC) 3.54 (s).
Anal. Calcd for C17H25F3O2 (318.38): C, 64.13; H, 7.91; F, 17.90.
Found: C, 64.86; H, 8.23; F, 17.24.
4. Experimental section
All manipulations of 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.
Toluene, n-hexane, diethyl ether, and tetrahydrofuran were
distilled over Na/benzophenone ketyl. Dichloromethane was
distilled over calcium hydride. The water contents of these solvents
were periodically controlled by Karl-Fischer coulometry by using a
Methrom 756 KF apparatus.
Benzene-d6 was stored over Na/K alloy and was degassed by
freezeepumpethaw cycles before being vacuum transferred
directly. CDCl3 was stored over 4 Å sieves. Unless otherwise noted,
all reagents were purchased from SigmaeAldrich. Poly-
methylaluminoxane (Witco) was used as a 10% solutions in toluene.
4.3. 2,4-Di-tert-buthyl-6-(2,2,2-trifluoro-1-hydroxy-1-phenyl-
ethyl)-phenol (8)
To a stirred solution of PhMgBr (25 mmol) in ether (50 mL) was
added dropwise a solution of 1-(2,4-di-tert-buthylphenyl)-2,2,2-

V.A. Tuskaev et al. / Journal of Organometallic Chemistry 797 (2015) 159e164
163
trifluoromethylethanone-1 (2.17 g, 7.2 mmol) in ether (25 mL) at
ꢁС in 1 h. After completion of the addition, the mixture was
for 12:
0
allowed to stand at room temperature overnight. The resulting
mixture was poured into an aqueous NH4Cl solution and extracted
with ether. The organic layer was removed, dried (Na2S04) and
evaporated under reduced pressure. Recrystallization of the crude
product from hexane gave 2.21 g (81%) of a colorless solid. 1H NMR
4.7. {2-[a-methyl-a-trifluoromethyl-methanolato]-4,6-di-tert-
butyl-phenolato}dichlorodi(propan-2-ol)titanium (13)
Yield e 0.8 g (70%). Anal. Calcd for C23H39Cl2F3O4Ti (555.32): C,
49.75; H, 7.08; Cl, 12.77; F, 10.26; Ti, 8.62. Found: C, 49.59; H, 6.87;
Cl, 12.64; F, 10.11; Ti, 8.76. 1H NMR (CDCl3): 1.28 (s, 9Н), 1.42 (s, 9Н),
1.67 (s, 9Н), 1.99 (s, 12Н), 3.09 (s, 2Н), 4.12 (br.s, 2H), 7.00e7.04 (m,
1Н), 7.34 (d, 1Н, J ¼ 2.3 Hz). 19F NMR (CDCl3): - 3.76 (s).
(CDCl3,
d
) 1.26 (s, 9Н), 1.37 (s, 9Н), 3.49 (s, 1Н) 7.03e7.10 (m, 1Н),
7.31e7.43 (m, 4Н) 7.44e7.56 (m, 3Н). 19F NMR (CDCl3,
d), 3.00 (s).
Anal. Calcd for C22H27F3O2 (380.44): C, 69.46; H, 7.15; F, 14.98.
Found: C, 69.85; H, 7.41; F, 14.57.
4.8. {2-[a-phenyl-a-trifluoromethyl-methanolato]-4,6-di-tert-
4.4. 2,4-Di-tert-buthyl-6-(2,2,2-trifluoro-1-hydroxy-1-
pentafluorophenyl-ethyl)-phenol (9)
butyl-phenolato}dichlorodi(propan-2-ol)titanium (14)
Yield - 0.13 г (42%). Anal. Calcd for C28H41Cl2F3O4Ti (617.39): C,
54.47; H, 6.69; Cl, 11.48; F, 9.23; Ti, 7.75. Found: C, 54.29; H, 6.56; Cl,
11.37; F, 9.12; Ti, 7.43. 1H NMR (toluene-d8, 25 ꢁC): 0.96 (br. s, 9H),
1.17 (s, 9H), 1.67 (s, 12H), 3.42 (br. s, 2H), 4.20 (s, 2H), 6.95e7.08 (m,
5H), 7.26 (s,1H), 7.50 (d,1H, J ¼ 2.3 Hz). 19F NMR (toluene-d8, 25 ꢁC):
- 71.96 (s).
A solution of 1.0 ml (8.1 mmol) of C6F5Br in 20 mL of Et2O was
cooled to ꢂ78 ꢁC, and 3.24 mL of nBuLi (2.5 M solution in hexane,
8.1 mmol) was added dropwise. The reaction mixture was stirred
at ꢂ78 ꢁC for 30 min, and then a solution of 1-(2,4-di-tert-buthyl-
phenyl)-2,2,2-trifluoromethylethanone-1 (1.1 g, 3.64 mmol) in
diethyl ether was added dropwise. The resultant solution was
stirred overnight at room temperature, cooled to 0 ꢁC, and then
quenched with an aqueous NH4Cl solution (50 mL) and extracted
with ether. The combined organic phase was dried over Na2SO4,
and the solvent was removed under reduced pressure. Recrystal-
lization of the crude product from hexane gave 2.99 g (82%) of a
colorless solid; mp 149e150 ꢁC. 1H NMR (300 MHz, CDCl3): 1.30 (s,
9Н), 1.37 (s, 9Н), 4.43 (t, 1Н, J ¼ 4.2 Hz), 6.76 (s, 1Н), 7.22e7.28 (m,
1Н), 7.38 (d, 1Н, J ¼ 2.2 Hz). 19F NMR (CDCl3) 1.39 (br. s,
3F), ꢂ59.84e60.05 (m, 2F), ꢂ73.21 to ꢂ73.26 (m, 1F), ꢂ82.96e83.13
(m, 2F). Anal. Calcd for C22H22F8O2 (470.41): C, 56.17; H, 4.71; F,
32.31. Found: C, 56.72; H, 4.95; F, 31.67.
4.9. {2-[a-pentafluorophenyl-a-trifluoromethyl-methanolato]-4,6-
di-tert-butyl-phenolato}dichlorodi(propan-2-ol)titanium (15)
Yield e 2.18 g (62%). Anal. Calcd for C28H36Cl2F8O4Ti (707.34): C,
47.54; H, 5.13; Cl, 10.02; F, 21.49; Ti, 6.77. Found: C, 47.31; H, 4.97; Cl,
9.95; Ti, 6.54. 1H NMR (CD2Cl2): 1.21 (s, 9H), 1.35 (d, J ¼ 6.2 Hz, 12H),
1.50 (s, 9H), 3.60 (br. s, 2Н), 6.93 (s, 1H), 7.40 (d, J ¼ 1H, 2.3 Hz). 19
F
NMR (CD2Cl2): - 75.15 (s, 3F), - 134.10 (br.s, 2F), - 152.58e152.68 (m,
1F), ꢂ161.42e161.64 (m, 2F).
4.10. {2-[a,a-diphenylmethanolato]-4,6-di-tert-butyl-phenolato}
dichlorodi(propan-2-ol)titanium (16)
4.5. 2,4-Di-tert-buthyl-6-(1-hydroxy-1-methyl-ethyl)-phenol (10)
Anal. Calcd for C33H46Cl2O4Ti (625.49): C, 63.37; H, 7.41; Cl,
11.34; Ti, 7.65. Found: C, 63.19; H, 7.20; Cl, 11.19; Ti, 7.83. 1H NMR
A solution of 2-bromo-4,6-di-tert-butylphenol (2.86 g,10 mmol)
in Et2O (20 ml) was added dropwise to a solution of nBuLi
(20 mmol) in Et2O (20 ml) at ꢂ78 ꢁC. The mixture was slowly
warmed to room temperature and stirred overnight. The solution
was cooled to ꢂ78 ꢁC, and a solution of acetone (1.47 ml, 20 mmol)
in Et2O (10 ml) was added dropwise. The reaction mixture was
stirred overnight at room temperature and then quenched with
30 ml of saturated NH4Cl (aq). The organic layer was separated,
dried over Na2SO4, filtered, and concentrated by distillation under
reduced pressure. Pure product (1.48 g, 56%) was obtained by col-
umn chromatography over silica (hexanes) as white solid. Anal.
Calcd for C17H28O2 (264.40): C, 77.22; H, 10.67; O, 12.10. Found: C,
77.13; H, 10.51. 1H NMR (300 MHz, CDCl3): 1.35 (s, 9Н), 1.42 (s, 9Н),
1.87 (s, 6Н), 5.70 (s, 2Н), 7.28 (s, 1Н), 7.43(s, 1Н).
(CD2Cl2,
3.78 (s, 2H), 4.55 (br.s, 2H), 4.67 (s, 2H), 6.76 (s, 1H), 7.39e7.16 (m,
11H). 13C NMR (CD2Cl2,
): 24.23, 30.07, 31.02, 34.40, 35.48, 70.64,
122.69, 126.21, 127.62, 128.52, 129.09, 131.86, 134.29, 144.51, 146.25.
d, J/Hz): 1.14 (s, 9H) 1.34 (d, J ¼ 5.9 Hz, 12H), 1.47 (s, 9H),
d
4.11. {2-[a,a-dimethylmethanolato]-4,6-di-tert-butyl-phenolato}
dichlorodi(propan-2-ol)titanium (17)
Anal. Calcd for C23H42Cl2O4Ti (501.35): C, 55.10; H, 8.44; Cl,
14.14; Ti, 9.55. Found: C, 54.87; H, 8.29; Cl, 14.02; Ti, 9.38. 1H NMR
(CDCl3): 1.41 (s, 9Н), 1.46 (s, 9Н), 1.85 (s, 12Н), 1.99 (s, 6Н), 3.09 (s,
2Н), 7.34 (m, 1Н), 7.64 (s, 1Н).
4.12. {2-[methanolato]-4,6-di-tert-butyl-phenolato}
4.6. {2-[a-trifluoromethyl-methanolato]-4,6-di-tert-butyl-
dichlorodi(propan-2-ol)titanium (18)
phenolato}dichlorodi(propan-2-ol)titanium (12)
Anal. Calcd for C21H38Cl2O4Ti (473.30): C, 53.29; H, 8.09; Cl,
14.98; Ti, 10.11. Found: C, 53.04; H, 7.91; Cl, 14.73; Ti, 10.00. 1H NMR
(CDCl3): 1.76 (s, 9Н), 1.85 (s, 9Н), 1.97 (s, 12Н), 3.09 (s, 2Н), 4.26 (br.s,
2H), 4.58 (m, 2Н), 7.76 (s, 1Н), 7.96 (s, 1Н).
To a stirred solution of 6 (0.304 g, 1 mmol) in 10 ml of dried
toluene a solution of Ti(O-iPr)2Cl2 (0.237 g, 1 mmol) in 10 ml of
toluene was added dropwise over 5 min. After the formation of a
dark purple precipitate, the mixture was heated to homogeniza-
tion. On cooling, the dark purple crystals that formed were filtered
off and washed with cold toluene. Yield e 0.188 г (36%). Anal. Calcd
for C22H37Cl2F3O4Ti (541.29): C, 48.82; H, 6.89; Cl, 13.10; F, 10.53; Ti,
8.84. Found: C, 48.65; H, 6.73; Cl, 12.87; F, 10.35; Ti, 8.92. 1H NMR
(CDCl3, 25 ꢁC) 1.40 (s, 9Н), 1.52 (s, 9Н), 1.98 (s, 12Н), 3.12 (s, 2Н), 3.89
(br.s, 2H), 5.05 (m, 1Н), 7.20 (s, 1Н), 7.38 (s, 1Н). 19F NMR (CDCl3,
25 ꢁC) 3.98 (s).
4.13. L2TiLi(OiPr)thf (19)
To
a
stirred solution of 2,4-Di-tert-butyl-6-(1,1,1,3,3,3-
hexafluoro-2-hydroxypropan-2-yl)phenol (0.372 g, 1 mmol) in
10 ml of dried THF a solution of TiLi(O-iPr)5 (0.35 g, 1 mmol) in
10 ml of THF was added dropwise over 5 min. After the formation of
a white precipitate, the mixture was heated to homogenization. On
cooling, the crystals were filtered off, washed with cold toluene and
Complexes 13-18 were prepared via a procedure similar to that

164
V.A. Tuskaev et al. / Journal of Organometallic Chemistry 797 (2015) 159e164
recrystallized from dichloromethane to give crystals suitable for X-
ray analysis. Yield e 0.111 g (24%). Anal. Calcd for C41H55F12LiO6Ti
(926.66): C, 53.14; H, 5.98; F, 24.60; Li, 0.75; Ti, 5.17. Found: C, 52.89;
H, 5.77; F, 24.47. 1H NMR (CDCl3): 1.70 (s, 18Н), 1.82 (s, 18Н), 1.88 (s,
6Н), 2.78 (s, 1Н), 4.20 (br.s, 1H), 4.62e4.69 (m, 8Н), 7.25e7.64 (m,
4Н).
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Acknowledgment
Financial support from the Russian Foundation of Basic Re-
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Appendix A. Supplementary data
Supplementary data related to this article can be found at http://
dx.doi.org/10.1016/j.jorganchem.2015.08.017.