Wang Z, et al. Sci China Chem August (2014) Vol.57 No.8
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structures were solved by direct methods and refined on F2
by full-matrix least squares techniques with anisotropic
thermal parameters for non-hydrogen atoms. Hydrogen at-
oms were placed at the calculated positions and were in-
cluded in the structure calculation without further refine-
ment of the parameters. All calculations were carried out
using the SHELXS-97 program.
Scheme 1 Activity comparison between complexes bearing –OPh (1a)
and –SPh (1b) side-arm [26].
2.2 Synthesis of the ligands and complexes
(E)-2,4-di-tert-butyl-6-((2-(phenylsulfinyl)phenylimino)meth-
yl)phenol (7a)
A mixture of the aniline 6a (6.2 g, 28.5 mmol) and
3,5-di-tert-butylsalicylaldehyde (6.7 g, 28.5 mmol) in etha-
nol (50 mL) in the presence of a catalytic amount of acetic
acid (3 mL) was refluxed until the reaction was complete.
The mixture was cooled to room temperature and the col-
lected yellow solid was washed with cool ethanol to give
Figure 1 Molecular structures of complexes 1a and 1b.
1
pure product. Yield: 8.72 g (71%). H NMR (300 MHz,
CDCl3, ppm): δ 12.81 (s, 1 H), 8.45 (s, 1 H), 8.16–8.17 (m,
1H), 7.68–7.12 (m, 10 H), 1.50 (s, 9 H), 1.31 (s, 9 H). 13C
NMR (300 MHz, CDCl3): δ 165.1, 158.0, 145.7, 145.0,
140.9, 138.9, 137.2, 131.9, 131.1, 129.1, 129.1, 127.4,
127.4, 126.0, 124.5, 118.0, 117.8, 35.1, 34.1, 31.4, 29.3.
Anal. calcd. for C27H31NO2S: C 74.79, H 7.21, N 3.23.
Found: C 74.40, H 7.22, N 3.01.
In this work, we designed and synthesized ligand 7a- and
7b-bearing sulfoxide groups to further elaborate the influ-
ence of the electronic and steric properties of the pendant
group on the catalyst behaviors during ethylene polymeriza-
tion. The corresponding titanium complexes of 7b showed
good activity even at 120 °C upon activation with modified
methyl aluminominato (MMAO). 1-Hexene and norbornene
(NBE) could incorporate into polyethylene in more than 30
mol%.
(E)-2,4-di-tert-butyl-6-((2-(2,6-diisopropylphenylsulfinyl)ph-
enylimino)methyl)phenol (7b)
Using a similar procedure to 7a, pure 7b was obtained.
Yield: 2.82 g (67%). 1H NMR (300 MHz, CDCl3, δ ppm): δ
11.91 (s, 1 H), 7.96–7.98 (m, 2 H), 7.27–7.45 (m, 3 H),
7.00–7.09 (m, 2H), 6.85–6.91 (m, 2 H), 3.75–3.70 (m, 2 H),
1.42 (s, 9 H), 1.30 (s, 9 H), 0.96 (d, J = 6.6 Hz, 12 H). 13C
NMR (75 MHz, CDCl3): δ 166.7, 157.7, 150.7, 147.8, 140.6,
136.9, 137.0, 132.0, 131.1, 128.6, 127.3, 126.4, 125.7,
124.7, 120.6, 117.9, 35.0, 34.0, 31.3, 29.4, 28.6, 24.4, 23.2.
Anal. calcd. for C33H43NO2S: C 76.55, H 8.37, N 2.71.
Found: C 76.58, H 8.29, N 2.71.
2 Experimental
2.1 General information
All manipulations were carried out using standard Schlenk
technique or glove-box under nitrogen or argon. Toluene,
THF, hexane, and dichloromethane were purified by an MB
SPS-800 (MBRAUN Company, Germany) prior to use.
Modified methylaluminoxane (MMAO) was purchased
from Akzo Chemical (Holland) as heptane solution (1.88
M). Molecular weights (Mw and Mn) and molecular-weight
distributions (Mw/Mn) of polymers were determined using a
Waters Alliance GPC 2000 series (WATERS, USA) at
135 °C (using polystyrene calibration, 1,2,4-trichloroben-
zene as solvent at a flow rate of 0.92 mL/min). 1H NMR and
13C NMR spectra were recorded on a Varian XL-300 MHz
and Varian XL-400 MHz spectrometer (VARIAN, USA).
Elemental analysis was performed by the Analytical Labor-
atory of Shanghai Institute of Organic Chemistry (CAS).
13C NMR data for polymers were obtained using CDCl3 as
the solvent at 25 °C. X-ray crystallographic data were col-
lected at 20 °C on a Bruker SMART diffractometer with
graphite-monochromated Mo-Kα radiation ( = 0.71073 Å).
The SADABS absorption correction was applied. The
[(E)-2,4-di-tert-butyl-6-((2-(phenylsulfinyl)phenylimino)-
methyl) phenol] Ti(IV)Cl3 (8a)
To a solution of TiCl4 (0.56 mL, 5.0 mmol) in toluene (30 mL)
was added dropwise a solution of 7a (2.0 g, 4.6 mmol) in tolu-
ene (30 mL) over 10 min at 78 ºC. The resulting mixture was
allowed to warm to room temperature and stirred for 3 h. The
generated dark-red solids were collected and washed with tol-
uene (3 × 20 mL). Pure product was recrystallized in toluene at
1
30 ºC. Yield: 2.0 g (74%). H NMR (400 MHz, CDCl3, δ
ppm): 8.46 (s, 1 H), 7.99–7.24 (m, 10 H), 6.48–6.46 (m, 1H),
1.61 (s, 9 H), 1.36 (s, 9 H) ppm. 13C NMR (100 MHz, CDCl3,
δ ppm): δ 168.1, 161.1, 150.1, 146.4, 137.0, 135.4, 134.5,
133.2, 133.1, 131.9, 130.6, 129.6, 128.2, 127.3, 126.1, 125.0,
35.4, 34.7, 31.2, 31.1, 29.8. Anal. calcd. for C27H30Cl3NO2STi: