Titanium(4+) and zirconium(4+) dichloride complexes with pyridinedicarboxylic acid derivatives as ethylene polymerization catalysts

Article abstract of DOI:10.1134/S0036023611040255

Titanium(4+) and zirconium(4+) complexes with pyridinedicarboxylic acid derivatives have been synthesized. The composition and structure of the synthesized 2,6-bis(diphenylhydroxymethyl)pyridine complexes have been corroborated by NMR and IR spectroscopy,

Full text of DOI:10.1134/S0036023611040255

ISSN 0036ꢀ0236, Russian Journal of Inorganic Chemistry, 2011, Vol. 56, No. 4, pp. 555–557. © Pleiades Publishing, Ltd., 2011.
Original Russian Text © O.V. Smirnova, T.A. Sukhova, M.V. Solov’ev, S.S. Galibeev, S.Ch. Gagieva, V.A. Tuskaev, B.M. Bulychev, 2011, published in Zhurnal Neorganicheskoi
Khimii, 2011, Vol. 56, No. 4, pp. 595–598.
COORDINATION
COMPOUNDS
Titanium(4+) and Zirconium(4+) Dichloride Complexes
with Pyridinedicarboxylic Acid Derivatives as Ethylene
Polymerization Catalysts
b
O. V. Smirnovaa, T. A. Sukhova†, , M. V. Solov’evc, S. S. Galibeeva,
S. Ch. Gagievac, V. A. Tuskaevc, and B. M. Bulychevc
a OOO NIOST, Kuzovlevskii trakt 2, build. 270, Tomsk, 634067 Russia
b Institute of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka, Moscow oblast, 142432 Russia
c Faculty of Chemistry, Moscow State University, Moscow, 119991 Russia
Received March 29, 2010
Abstract—Titanium(4+) and zirconium(4+) complexes with pyridinedicarboxylic acid derivatives have been
synthesized. The composition and structure of the synthesized 2,6ꢀbis(diphenylhydroxymethyl)pyridine
complexes have been corroborated by NMR and IR spectroscopy, and elemental analysis. The complexes
activated with methylaluminoxane (MAO) are catalytically active in ethylene polymerization, Depending on
the Ti/AlMAO ratio, the catalytic activity of the complexes varies between 90 and 420 kg PE/mol Ti h atm.
DOI: 10.1134/S0036023611040255
†
At present, there is keen interest in homogeneous was distilled in an argon atmosphere. SiO2, boron
catalysis by coordination (postꢀmetallocene) cataꢀ nitride, Polysorbꢀ1, graphite, magnesium, and
lysts. These catalysts afford a still higher polymer outꢀ pyridinedicarboxylic acid were purchased from Fluka
put rate per mole of metal than the metallocenes. Furꢀ and were used as received. MAO (Witco) was used as
thermore, they have extended the area of application its 10% solution in toluene.
of the postꢀmetallocenes to the copolymerization of
polar and nonpolar monomers.
The NMR spectra of solutions in tolueneꢀd8 and
CDCl3 were recorded on Bruker WPꢀ300 and Bruker
AMXꢀ400 spectrometers; IR spectra, on a Nicolet
MagnaꢀIR 750 spectrophotometer. Elemental analyꢀ
ses were carried out on Carlo Erba 1106 and Carlo
Erba 1108 analyzers.
Synthesis of 2,6ꢀbis(diphenylhydroxymethyl)pyriꢀ
dine (1). A solution of dimethyl pyridineꢀ2,6ꢀdicarꢀ
boxylate (1.95 g, 0.01 mol) in diethyl ether was cooled
Olefin polymerization catalytic systems based on
iron(II)
and
cobalt(II)
complexes
with
bis(imino)pyridyl ligands and methylaluminoxane
(MAO) as the cocatalyst were reported for the first
time in 1995–1999 [1, 2]. Subsequent research in this
area has mainly been focused on the synthesis of amiꢀ
noimine (N,N,N) and oxoimine (N,O) ligands, their
use in complexation reactions, and testing of the
resulting complexes in ethylene and propylene polyꢀ
merization [3–6].
Here, we report the synthesis of a new group of
ONOꢀtype ligands based on pyridineꢀ2,6ꢀdicarboxyꢀ
lic acid, titanium and zirconium coordination comꢀ
pounds with this ligand, and the catalytic properties of
the new complexes in ethylene polymerization.
to
0 С, and a diethyl ether solution of PhMgBr
°
obtained from Mg (0.72 g, 0.03 mol) and bromobenꢀ
zene (4.75 g, 0.03 mol) was added in drops under stirꢀ
ring. After conducting the reaction for 2–3 h, the
reaction mixture was decomposed with a saturated
solution of ammonium chloride. The organic layer was
washed with water, dried with anhydrous Na2SO4, and
evaporated, and the product was recrystallized from
1
toluene. Yield: 3.02 g (69%); mp 189°C. H NMR
(CDCl3): 6.65 (s, 2H, OH), 7.17–7.70 (m, 23HAr).
For C31H25NO2 anal. calcd. (%): C, 83.95; H, 5.68;
N, 3.16. Found (%): C, 83.80; H, 5.09; N, 3.07.
EXPERIMENTAL
The complexes were synthesized in an argon atmoꢀ
sphere. Tetrahydrofuran, dichloromethane, diethyl
ether, toluene, hexane, and ethyl acetate (reagent
trade) were further purified by standard techniques
[7]. Dimethyl pyridineꢀ2,6ꢀdicarboxylate was syntheꢀ
sized via a procedure described in [8]. TiCl4 (Fluka)
Synthesis
of
2,6ꢀbis(diꢀ(pentafluorophenyl)ꢀ
hydroxymethyl)pyridine (2). Pentafluorobromobenꢀ
zene (1.25 mL, 10 mmol), dissolved in diethyl ether
(30 mL), was placed in a twoꢀneck flask predried by
slight heating and filled with argon. The flask was
cooled to –78°C, and butyllithium (8.92 mmol, 1 mL
of a 10 M solution in hexane) was added under stirring.
†
Deceased.
555

556
SMIRNOVA et al.
Zirconium(4+) tetraphenylꢀ2,6ꢀpyridinedimethoxiꢀ
de dichloride ( ): yield, 0.85 g (71%).
Q
sp, kg PE/mol Ti h atm
4
550
500
450
400
350
300
250
200
150
100
50
For C31H23NO2ZrCl2 anal. calcd. (%): C, 61.68; H,
3.84; Cl, 11.75; N, 2.32; Zr, 15.11. Found (%): C,
61.40; H, 3.69; Cl, 11.57; N, 2.25; Zr, 15.20.
1
IR,
Cl).
Titanium(4+) tetraperfluorophenylꢀ2,6ꢀpyridinediꢀ
methoxide dichloride ( ): yield, 1.13 g (62%).
ν
, cm–1: 498 (Zr–O), 430 (Zr–N), 349 (Zr–
1а
1b
1c
5
For C31H3NO2F20TiCl2 anal. calcd. (%): C, 40.47;
H, 0.33; Cl, 7.71; N, 1.52; Ti, 5.20. Found (%): C,
40.06; H, 0.52; Cl, 7.68; N, 1.47; Ti, 5.20.
IR,
, cm–1: 520 (Ti–O), 454 (Ti–N), 390 (Ti–Cl).
ν
1H NMR (tolueneꢀ
Zirconium(4+)
d
8): 7.38–7.50 (m, 3HAr).
0
10 20 30 40 50 60 70 80
, min
t
tetraperfluorophenylꢀ2,6ꢀ
pyridinedimethoxide dichloride (6): yield, 0.97 g (51%).
For C31H3O2NO2F20ZrCl2 anal. calcd. (%): C,
38.65; H, 0.31; Cl, 7.36; N, 1.45; Zr, 9.47. Found (%):
C, 38.06; H, 0.22; Cl, 7.23; N, 1.34; Zr, 9.17.
Polyethylene yield from ethylene polymerization per unit conꢀ
centration of the catalyst as a function of time on stream for
homogeneous catalyst
catalysts supported on (1a) graphite, (1b) Polysorbꢀ1, and (1c
1 and the corresponding heterogeneous
IR,
Cl).
1H NMR (tolueneꢀ
ν
, cm–1: 520 (Zr–O), 454 (Zr–N), 347 (Zr–
)
–5
boron nitride (30°C, [Ti] = 7
1050 mol/mol).
×
10 mol/L, Al
/Ti =
MAO
d8): 7.26–7.50 (m, 3HAr).
The finished precatalysts were transferred into
tubes, which were filled with argon and sealed for subꢀ
sequent use in the catalytic process.
Heterogenized catalysts were synthesized as folꢀ
lows. The support (SiO2, boron nitride, Polysorbꢀ1, or
graphite; 5 g) was placed in a Schlenk reactor, and the
reactor was pumped at 40–60°C for 3 h. Next, the
support was dispersed in 20 mL of dry toluene and a
After the mixture was stirred for 1 h, dimethyl pyriꢀ
dineꢀ2,6ꢀdicarboxylate (0.62 ml, 049 g, 2.5 mmol) was
added. The flask was gradually warmed to room temꢀ
perature, and the reaction mixture was stirred for 12 h.
Thereafter, the reaction mixture was neutralized with
a saturated solution of ammonium chloride and the
organic layer was separated and evaporated. The prodꢀ
uct was isolated by chromatographing on a
2 15 cm
×
solution of complex
3 (0.0002 mol, 0.089 g) was
SiO2ꢀpacked column with the diethyl ether : hexane =
1 : 5 eluent and was crystallized from toluene. Yield:
0.87 g (44%); mp 139°C. 1H NMR (CDCl3): 6.60 (s,
2H, OH), 7.3–7.55 (m, 3HAr).
For C31H5O2NF20 anal. calcd. (%): C, 46.35; H,
0.63; N, 1.74. Found (%): C, 46.05; H, 0.87; N, 1.36.
added. The slurry was stirred for 1 h at room temperaꢀ
ture, the toluene was pumped out, 2 mL of a toluene
solution of MAO was introduced into the reactor
(Al/Ti = 1000), the slurry was transferred into tubes,
and the tubes were sealed for subsequent use.
Ethylene polymerization was carried out in hepꢀ
tane in a 200ꢀcm3 steel reactor at an ethylene pressure
of 11 atm. Before the reaction, the reactor was pumped
Synthesis of titanium(4+) and zirconium(4+) comꢀ
plexes. The complexes were synthesized via the same
for 1 h at 90
ature. Heptane (60 mL), MAO (
°
С
and was then cooled to the preset temperꢀ
procedure. The ligand (1 or 2, 0.001 mol) and toluene
6
×
10–4 mol), and ethꢀ
(10 mL) were placed in a twoꢀneck flask with a magnetic
stirrer in an argon atmosphere, and 0.22 mL of 10 M
ylene were introduced into the reactor under stirring.
Polymerization was initiated 15–20 min after the
completion of the preparatory operations by breaking
the glass tube with the catalyst in the reactor. The reacꢀ
tion was terminated by adding a 10% HCl solution in
ethanol to the contents of the reactor. The polymer
was filtered, washed with ethanol and water, and dried
butyllithium (0.0022 mol) in
78 . Thereafter, the reaction mixture was slowly
brought to room temperature, was stirred for 4 h, and was
then cooled to –78 . Next, TiCl4 (0.11 mL, 0.001 mol)
nꢀhexane was added at
⎯
°
С
°
С
or ZrCl4 (0.23 g) was added and the mixture was stirred
for another 12 h. The inorganic substances were filꢀ
tered, the organic layer was evaporated, and the prodꢀ
uct was recrystallized from toluene.
to constant weight in vacuo at 50–60 С.
°
Titanium(4+)
pyridinedimethoxiꢀde dichloride (
(60%).
For C31H23NO2TiCl2 anal. calcd. (%): C, 66.45; H,
4.14; Cl, 12.66; N, 2.50; Ti, 8.54. Found (%): C,
66.02; H, 4.07; Cl, 12.29; N, 2.47; Ti, 8.50.
tetraphenylꢀ2,6ꢀ
3): yield, 0.68 g
RESULTS AND DISCUSSION
We demonstrated earlier that titanium complexes
with diol ligands are potent ethylene polymerization
catalysts [9]. In order to find new postꢀmetallocene
catalysts for olefin polymerization, we synthesized
titanium(4+) and zirconium(4+) compounds with triꢀ
IR, 1 and 2 by reacting dimethyl
, cm–1: 557 (Ti–O), 460 (Ti–N), 367 (Ti–Cl). dentate ONO ligands
ν
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 56 No. 4 2011

TITANIUM(4+) AND ZIRCONIUM(4+) DICHLORIDE COMPLEXES
557
pyridineꢀ2,6ꢀdicarboxylate with the corresponding
organometallic compounds (scheme). The introducꢀ
tion of bulky, functionalized, aromatic substituents
into the ligand changes the molecular geometry of the
complex. The electronꢀwithdrawing properties and
volume of the substituents were regulated by introducꢀ
ing fluorine atoms into the aromatic moiety of the
ligand.
The complexes were obtained by metalating the
ligands with butyllithium in hexane followed by comꢀ
bining the resulting salts with 1 equiv of TiCl4 or ZrCl4
(scheme). The formation of a coordination compound
was indicated by the appearance of M–O and M–Cl
stretching bands in the IR spectrum ((Zr–O) 520 cm–1,
(Zr–N) 454 cm–1, (Zr–Cl) 347 cm–1).
PhMgBr, Et O
2
or C F Li
R
1. BuLi, C H CH
3
6
2. TiCl or ZrCl
5
R
R
R
6
5
4
4
R
N
O
O
R
R
N
N
R
O
O
M
O
O
OH
OH
Cl
Cl
1
2
R = C6H5
R = C6F5
3
4
5
6
R = C6H5, M = Ti
R = C6H5, M = Zr
R = C6F5, M = Ti
R = C6F5, M = Zr
Scheme
Testing of the precatalysts demonstrated that
the zirconium complexes are inactive in ethylene
polymerization. The titanium complexes in the
presence of MAO show a catalytic activity of 360–
420 kg PE/mol Ti h atm at Ti : AlMAO = 1 : 200. The
polymerization rate is temperatureꢀdependent, and
ACKNOWLEDGMENTS
This work was supported by the Russian Foundaꢀ
tion for Basic Research (grant nos. 08ꢀ03ꢀ12134, 09ꢀ
03ꢀ01060, and 09ꢀ03ꢀ12265ꢀofi_m).
the highest rate is observed at 30
activity of 450 kg PE/mol Ti h atm. As the temperature
is raised to 50 , the catalytic activity falls to 270 kg
°
С, with a catalytic
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