Syntheses, reactions, and ethylene polymerization of titanium complexes with [N,N,S] ligands

Article abstract of DOI:10.1039/c0dt01800g

Tridentate dianionic arylsulfide free ligands [ArNHCH₂C ₆H₄NHC₆H₄-2-SPh] (Ar = Ph (3a); Ar = 2,4,6-trimethylphenyl (3b); Ar = 2,6-diisopropylphenyl (3c)) have been prepared by reduction of the corresp

Full text of DOI:10.1039/c0dt01800g

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Volume 40 | Number 30 | 14 August 2011 | Pages 7653–7792
Themed issue: d0 organometallics in catalysis
ISSN 1477-9226
COVER ARTICLE
Jin et al.
Syntheses, reactions, and ethylene
polymerization of titanium complexes
with [N,N,S] ligands
1477-9226(2011)40:30;1-V

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PAPER
Syntheses, reactions, and ethylene polymerization of titanium complexes with
[N,N,S] ligands†
Ai-Quan Jia,a Jian-Qiang Wang,b Ping Hua and Guo-Xin Jin*a
Received 20th December 2010, Accepted 18th February 2011
DOI: 10.1039/c0dt01800g
Tridentate dianionic arylsulfide free ligands [ArNHCH2C6H4NHC6H4-2-SPh] (Ar = Ph (3a); Ar =
2,4,6-trimethylphenyl (3b); Ar = 2,6-diisopropylphenyl (3c)) have been prepared by reduction of the
corresponding imine compounds [ArN CHC6H4NHC6H4-2-SPh] (Ar = Ph (2a); Ar =
2,4,6-trimethylphenyl (2b); Ar = 2,6-diisopropylphenyl (2c)) with LiAlH4 in high yields. Reactions of
TiCl4 with the tridentate dianionic arylsulfide free ligands (3a–3c) afford five-coordinate and
2
four-coordinate titanium complexes [kS, k N-(ArNHCH2C6H4NHC6H4-2-SPh)TiCl2] (Ar = Ph (4a);
2
Ar = 2,4,6-trimethylphenyl (4b)] and [k N-(ArNHCH2C6H4NHC6H4-2-SPh)TiCl2] (Ar =
2,6-diisopropylphenyl (4c)], respectively. The molecular structures of compounds 2b, 2c, 3b and 3c·HCl
have been characterized by single crystal X-ray diffraction analyses. Complexes 2a–4c are characterized
by IR,1H-NMR spectra, and elemental analysis. EXAFS spectroscopy performed on complexes 4b and
4c reveals the expected different coordination geometry due to steric hindrance effect. When activated
by excess methylaluminoxane (MAO), 4a–4c can be used as catalysts for ethylene polymerization and
exhibit moderate to good activities.
104 gPE·mol-1Ti·h-1).8 The soft pendant donors in his paper are
Introduction
phosphorous and sulfur atoms, while the hard donors are nitrogen
Ever since the discovery of Ziegler–Natta catalysis,1 non-
and oxygen atoms. Wu reported the nickel complexes with sulfur-
metallocene molecular catalysts, including both early and late
containing tridentate monoanionic ligand have higher catalytic
transition metal complexes, have attracted great attention.2–4
activity than [N,N] bidentate anilido–imino nickel complexes to-
wards norbornene polymerization.9 Additionally, Okuda reported
that group 4 complexes with tetra-dentate ligand [SO-O-S] showed
good selectivity and activity towards polymerization of styrene.10
However, despite the extensive investigations of organometallic
complexes of chelating anilido-imine ligands and the utility of
monoanionic tridentate [N-NS] nickel and palladium complexes
in norbornene polymerization,9 few dianionic tridentate [N-N-S]
ligands of titanium(IV) complexes have been described and their
reaction chemistry is rarely developed. Previously, Our group have
reported Ni, Cu, Ir catalysts containing [NN-] ligands for ethylene
and norbornene polymerization.11 Furthermore, heterogeneous
Ti, Zr and Hf catalysts,12 as well as homogeneous Ti, Zr
catalysts containing [O-NO-] and [O-NS-] ligands,13 have also
been studied in our group. Herein, we describe the syntheses,
X-ray crystallographic characterizations, EXAFS spectroscopy
experiment, and ethylene polymerization chemistry of dianionic
tridentate arylsulfide [N-N-S] titanium(IV) complexes (Scheme 1).
Complexes containing chelating anilido-imine ligands are among
the typical examples due to their readily preparation as well as
versatile modification of the steric and electronic demands.5 It
has been widely known that zirconium complexes bearing b-
diketiminate ligands with electron-withdrawing groups displayed
high catalytic activities for ethylene polymerization (1.1 ¥ 107
gPE·mol-1Zr·h-1) and produced polyethylene with narrow molec-
ular weight distribution (PDI ~ 2.7).6 Wu and Huang reported
group 4 complexes with bis(b-diketiminate) ligands for ethylene
polymerization and copolymerization with norbornene.7
In 2004, Gibson reported that group 4 metal complexes
containing phenoxy-amide ligands bearing soft pendant donors
are shown to give more highly active ethylene polymerization
catalysts than the counterparts containing hard donors or systems
without a pendant donor (1.95 ¥ 107 gPE·mol-1Ti·h-1 vs. 9.6 ¥
aShanghai Key Laboratory of Molecular Catalysis and Innovative Ma-
terials, Department of Chemistry, and Key Lab of Molecular Engi-
neering of Polymers of Chinese Ministry of Education, Department of
Macromolecular Science, Fudan University, Shanghai, 200 433, China.
E-mail: gxjin@fudan.edu.cn; Fax: +86-21- 65641740; Tel: +86-21-
65643776
Results and discussion
bShanghai Synchrotron Radiation Facility, Shanghai Institute of Applied
Physics, Chinese Academy of Sciences, Shanghai, 201204, P. R. China
† CCDC reference numbers 805154–805157. For crystallographic data in
CIF or other electronic format see DOI: 10.1039/c0dt01800g
Syntheses and characterizations of the titanium complexes
Three [N,N,S] tridentate dianionic free ligands with various
sterically hindered substituents were synthesized. The synthetic
7730 | Dalton Trans., 2011, 40, 7730–7736
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The Royal Society of Chemistry 2011
©

Scheme 3 Acidification of free ligand 3c.
were further confirmed by single-crystal X-ray diffraction analysis
˚
(Fig. 1–4). In 2b, the C(7)–N(2) bond length is 1.259(3) A, for 3b,
˚
the C(7)–N(1) bond length is 1.471(3) A, which is typical of a
carbon-nitrogen single bond. For 2c, the C(7)–N(2) bond distance
˚
is 1.262(3) A, similar to that in 2b. In 3c·HCl, the C(19)–N(2)
˚
bond length is 1.517(4) A, longer than that in 3b, and much longer
˚
than the corresponding C(7)–N(2) bond in 2c (1.262(3) A). The
C(6)–C(7)–N(2) bond angle in 2b is 125.9 (3)◦, which is similar
to that in 2c (126.1(3)◦). In 3b, the C(1)–C(7)–N(1) bond angle is
111.2(2)◦, smaller than that in 2b, and similar to the bond angle of
C(14)–C(19)–N(2) in 3c·HCl (114.8(3)◦). In addition, the chloride
anion in 3c·HCl is nearer to N(2), as the Cl ◊ ◊ ◊ N(2) and Cl ◊ ◊ ◊ N(1)
Scheme 1 Synthesis of titanium complexes 4a–4c.
route for these tridentate free ligands is shown in Scheme 2. Con-
densation of 2-fluorobenzaldehyde with various anilines afforded
imines 1a–1c in high yields. The reactions of 1a–1c with PhS-2-
C6H4NHLi proceeded completely under 40 ◦C. Pure products of
2a–2c were obtained as yellow crystals by initial chromatography
and then crystallization from ethanol, in about 50% yields. The
aniline–arylamido derivatives 3a–3c were readily prepared in high
yields by reduction of the corresponding aniline–arylimine 2a–2c
with excess LiAlH4 in cool diethyl ether. 3a and 3b were light
yellow powder, while 3c was somewhat oily. However, it is worth
noting that excess HCl in the workup would lead to acidification
of compouns 3a–3c. For example, when compound 3c combined
with one molecule of HCl, it became to be 3c·HCl (Scheme 3).
All of these free ligands were proved by 1H NMR and compared
with known compounds. The chemical shift of CH N protons
in compounds 2a–2c are 8.54, 8.22, and 8.27 ppm, respectively.
˚
distance are 3.081(4) and 3.230(3) A, respectively.
1
The signals disappeared in H NMR spectra of compounds 3a–
3c, while new signals appeared and identified as NH (3.51, 2.75,
2.90 ppm) and CH2 (4.08, 3.88, 4.19 ppm) protons, indicating the
CH N (imine) has been transformed to CH2NH (amine). The
IR spectra also verified the transformation of imine to amine,
for example, in the spectrum of 3a, there were two absorption
peaks at 3359 cm-1 and 3217 cm-1, indicating the existence of
two secondary amines. The structures of 2b, 2c, 3b and 3c·HCl
Fig. 1 Molecular structure of 2b with thermal ellipsoids drawn at the
30% level.
Scheme 2 Synthetic routes to free ligands 3a–3c.
The Royal Society of Chemistry 2011
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Dalton Trans., 2011, 40, 7730–7736 | 7731
©

Fig. 4 Molecular structure of 3c·HCl with thermal ellipsoids drawn at
the 30% level.
Fig. 2 Molecular structure of 2c with thermal ellipsoids drawn at the 30%
level.
obvious coordination of the two nitrogen atoms to the titanium
metal. Chemical shift of protons (NCH2) in complexes 4a–4c
were shifted downfield 0.11, 0.98, and 0.70 ppm compared to free
ligands, respectively. The absorption peaks of secondary amine in
IR spectra of 3a–3c were no longer observed for complexes 4a–4c.
The local atomic environment and charge state of Ti in compounds
4b and 4c were investigated by X-ray absorption spectroscopy,
including extended X-ray absorption fine structure (EXAFS) and
X-ray absorption near edge structure (XANES) (Fig. 5, 6). The
pre-edge at about 4970 eV in XANES spectra can be assigned
to 1s→3d electron transition. The observed differences in the
intensity of pre-edge peaks are consistent with the difference in
the coordinated model.14 The EXAFS spectra allows us to get
information on the environment around the metal center, which
has already been used for the characterization of Ti complexes for
ethylene polymerization.15 The fitting of the Ti–K-edge EXAFS
spectra (Table 1) of both investigated complexes was performed
using a two shell model, in which the first coordination shell
˚
at about 1.8 A consists of the two coordinating nitrogen atoms
of the diimine ligand group, the second shell of the chlorine
˚
and sulfur backscatterer at about 2.3–2.5 A. With the help of
Fig. 3 Molecular structure of 3b with thermal ellipsoids drawn at the
30% level.
The first attempt to synthesize complexes 4a–4c involved two
steps: (1) deprotonation of the free ligands with 2 equiv. nBuLi; (2)
reaction of the lithium salts with TiCl4 in toluene. However, the
reactions seemed to be more complicated than they were expected,
and the desired products were not isolated successfully. We tried to
prepare complexes 4a–4c based on our group’s previous work,13f by
the reaction of TiCl4 with 1 equiv. free ligand without any base in
toluene at low temperature for more than 12 h. Attempts to apply
the method to the preparation of 4a–4c proved to be accessible
(Scheme 1). The yellow solution turned to be red immediately,
when the reaction was complete, the suspension was filtered and
the precipitate was washed with toluene and hexane for three
times, sequentially. The complexes were fully characterized by
1H NMR and elemental analyses (see Experimental Section).
The two NH signals in 1H NMR spectra of 3a–3c (3.51 and
7.61 ppm for 3a; 2.75 and 8.02 ppm for 3b; 2.90 and 7.70 ppm
Fig. 5 Ti K-edge XANES spectra of sample for 4b. Inset: Fourier
transform of experimental data and fit for 4b.
1
for 3c) disappeared in the H NMR spetra of 4a–4c, indicating
7732 | Dalton Trans., 2011, 40, 7730–7736
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©

exhibited the highest activity about 1.5 ¥ 106 gPE·molTi-1·h-1. The
influence of polymerization temperature has also been studied.
As it demonstrates in Table 2, when the temperature goes up
from 20 to 60 ◦C, the activity of 4c firstly obviously increases
and then decreases a little. The highest activity appears at 40 ◦C.
Different ratio of Al/Ti also influences the catalytic behavior of
the catalysts, for example, in 4c/MAO system, the activity goes
up with the increased amount of MAO and achieves the highest
activity when the ratio of Al/Ti is 1000, but it decreases when
more MAO is added. The activity of complex 4c, having a bulky
iso-propyl group, is somewhat higher than that of complexes 4a
and 4b.
Table 1 Fit parameters of Ti EXAFS spectra for sample 4b and 4c
2
2
˚
Shell
N
R
s (10-3 A )
DE0 (eV)
4b
4c
Ti–N
Ti–Cl
Ti–S
Ti–N
Ti–Cl
1.7 0.2
1.8 0.3
0.9 0.1
2.1 0.3
2.3 0.2
1.84 0.02
2.32 0.02
2.46 0.02
1.84 0.02
2.32 0.02
8.1 1.8
3.7 0.7
15.0 3.5
4.1 0.6
9.3 0.9
-14.3 2.9
4.2 0.6
12.4 3.1
-4.2 0.7
7.1 2.0
The polymerization temperature and the ratio of Al/Ti has
little influence on the molecular weight of polyethylene, the Mv of
polymer was about 105–106 gmol-1.
Conclusions
A series of titanium complexes with tridentate dianionic arylsul-
fide ligands [NNSR]2- have been prepared. The routes employed
proved to be effective with preparation of both compounds 3a–
3c and complexes 4a–4c. The molecular structures of compounds
2b, 2c, 3b and 3c·HCl have been characterized by single X-ray
diffraction analysis. Under the guidance of EXAFS spectroscopy
analysis, it is found that when the substituent R1 is varied from H
i
2
Fig. 6 Ti K-edge XANES spectrum of sample for 4c. Inset: Fourier
transform of experimental data and fit for 4c.
to Pr, both five-coordinate [kS, k N-(ArNHCH2C6H4NHC6H4-
2-SPh)TiCl2] (Ar Ph (4a); Ar 2,4,6-trimethylphenyl
=
=
2
(4b)] and four-coordinate and [k N-(ArNHCH2C6H4NHC6H4-2-
SPh)TiCl2] (Ar = 2,6-diisopropylphenyl (4c)] titanium complexes
were synthesized, reflecting that the steric hindrance plays a
significant role on the geometry of complexes. When activated by
excess methylaluminoxane (MAO), these complexes can be used as
catalysts for ethylene polymerization. The activities of complexes
EXAFS analysis, the solid state structure of 4b and 4c were
found to be five coordinate and four coordinate titanium com-
2
plexes as [kS, k N-(ArNHCH2C6H4NHC6H4-2-SPh)TiCl2] (Ar =
2
2,4,6-trimethylphenyl (4b)] and [k N-(ArNHCH2C6H4NHC6H4-
2-SPh)TiCl2] (Ar = 2,6-diisopropylphenyl (4c)] (Fig. 5–6). It is
assumed that the iso-propyl was too crowded to form four-
coordinate complex 4c, as a result, we proposed 4a was a
i
4a–4c increase as the R1 group is replaced from H to Pr. The
highest activity can reach ca.106 gPE·molTi-1·h-1.
2
five-coordinate complex as [kS, k N-(PhNHCH2C6H4NHC6H4-
2-SPh)TiCl2].
Experimental
Ethylene polymerization. The prepared complexes were briefly
investigated in ethylene polymerization. Titanium complexes 4a–
4c showed moderate to good activities under the initiation of
MAO. The results are summarized in Table 2.
General considerations
All the operations were carried out under pure argon atmosphere
using standard Schlenk techniques. Tetrahydrofuran (THF),
hexane, and toluene were distilled from sodium-benzophenone.
Dichloromethane was distilled from calcium hydride. Com-
mercial reagents, namely, TiCl4, methylaluminoxane (MAO),
LiAlH4, nBuLi, 2-fluorobenzaldehyde, aniline, 2,4,6- trimethylben-
zenamine and 2,6-diisopropylbenzenamine were purchased from
ACROS Co. The free ligands 3a–3c were prepared according to
the modified literature.9
In the 4a–4c/MAO systems, the red mixture turned into
transparent yellow immediately as MAO was charged, indicating
the active species had better solubility in toluene. Ethylene con-
sumption continued during 30 min of polymerization. Complex 4c
Table 2 Ethylene polymerization results with titanium complexes 4a–4ca
Entry Catalyst Al/Ti ratio T/◦C Time/min Activityb Mvc ¥ 10-4
1H (400 MHz) NMR measurements were obtained on a Bruker
AC400 spectrometer in CDCl3 solution. Elemental analyses for C
and H were carried out on an Elementar III Vario EI analyzer.
1
2
3
4
5
6
7
8
4a
4b
4c
4c
4c
4c
4c
4c
1000
1000
500
1000
1500
2000
1000
1000
20
20
20
20
20
20
40
60
30
30
30
30
30
30
30
60
250
600
700
1250
1100
700
1500
1300
192
262
96
194
361
364
124
153
2a–2c. A solution of n-butyllithium (12.5 mL, 20.0 mmol) was
added slowly to a solution of 2-(phenylthio)aniline (4.02 g, 20.0
mmol) in THF (40 mL) at - 78 ◦C, and the reaction mixture
was warmed to room temperature and stirred overnight. This pale
suspension was added to a solution of 1a–1c (20.0 mmol) in THF
(20 mL) at room temperature. After stirring for 12 h at 40 ◦C,
the red transparent solution was quenched with H2O (20 mL)
a Conditions: [Ti] 10 mmol, toluene = 50 mL, ethylene pressure = 1 atm. b 103
gPE·molTi-1·h-1. c Mv measured by the Ubbelohde calibrated viscosimeter
technique.
This journal is
The Royal Society of Chemistry 2011
Dalton Trans., 2011, 40, 7730–7736 | 7733
©

and extracted with n-hexane. The organic phase was combined
and evaporated to dryness in vacuo to give the crude product
as yellow oil. Pure product was obtained as yellow crystals by
recrystallization from ethanol in about 50% yield.
6H, Ar–H), 7.36–7.45 (m, 3H, Ar–H), 7.78 (d, 1H, Ar–H), 8.66
(d, 2H, Ar–H). IR (KBr): n = 2917, 1716, 1624, 1583, 1460, 1377,
1300, 1153, 723 cm-1. Anal. Calc. for C28H26N2SCl2Ti: C, 62.12;
H, 4.84; N, 5.17; Found: C, 62.23; H, 4.89; N, 5.14.
2a. 1H NMR (CDCl3, 400 MHz): d 6.83 (t, 1H, Ar–H), 6.98–
7.43 (m, 16H, Ar–H), 7.61 (d, 1H, Ar–H), 8.54 (s, 1H, CH N),
11.45 (s, 1H, NH).
4c. This complex was prepared as described above for 4a,
starting from 3c (0.47 g, 1.0 mmol), and TiCl4 (1.0 mL, 1.0 mmol).
Workup afforded 4c (0.21 g, 78%) as purple red powder. 4c H
1
NMR (CDCl3, 400 MHz): d 1.08 (d, 12H, CH(CH3)2), 2.78 (hept,
2H, CH(CH3)2),, 4.56 (s, 2H, CH2), 6.10 (s, 1H, Ar–H), 6.38 (d,
1H, Ar–H), 6.80 (d, 1H, Ar–H), 6.90 (t, 1H, Ar–H), 7.15–7.55 (m,
10H, Ar–H), 8.90 (s, 2H, Ar–H). IR (KBr): n = 2857, 1716, 1460,
1376, 1301, 1254, 1112, 726 cm-1. Anal. Calc. for C31H34N2SCl2Ti:
C, 63.82; H, 5.53; N, 4.80; Found: C, 63.85; H, 5.59; N, 4.75.
2b. 1H NMR (CDCl3, 400 MHz): d 2.05 (s, 6H, o-Me), 2.28 (s,
3H, p-Me), 6.84 (m, 3H, Ar–H), 6.98–7.09 (m, 6H, Ar–H), 7.28–
7.38 (m, 5H, Ar–H), 7.62 (d, 1H, Ar–H), 8.22 (s, 1H, CH N),
11.19 (s, 1H, NH).
2c. 1H NMR (CDCl3, 400 MHz): d 1.12 (d, 12H, CH(CH3)2),
3.06 (hept, 2H, CH(CH3)2), 6.82–6.88 (m, 1H, Ar–H), 6.98–7.29
(m, 13H, Ar–H) 7.36 (d, 1H, Ar–H), 7.58 (d, 1H, Ar–H), 8.27 (s,
1H, CH N), 11.09 (brs, 1H, NH).
Single-crystal X-ray structure determination of compounds 2b,
2c, 3b and 3c·HCl. For compounds 2b, 2c, 3b and 3c·HCl, a
single crystal suitable for X-ray analysis was sealed into a glass
capillary, all the intensity data of the single crystal were collected
on the CCD-Bruker Smart APEX system. All determinations of
the unit cell and intensity data were performed with graphite-
3a–3c. To a suspension of LiAlH4 (0.76 g, 20.0 mmol) in ether
(20 mL) was slowly added a solution of ligand 2a–2c (5.0 mmol) in
ethyl ether (30 mL). After the mixture was stirred for 2 h at room
temperature, water (13 mL) and HCl (20%; 20 mL) aqueous were
added sequentially at 0 ◦C. The organic phase was separated and
washed with water (15 mL ¥ 3). The organic layers were dried with
anhydrous MgSO4. The solvent was removed under vacuum, and
the pure product 3a–3c was obtained as yellow solid in about 90%
yield.
˚
monochromated Mo-Ka radiation (l = 0.71073 A). All data were
collected at room temperature using the w-scan technique. These
structures were solved by direct methods, using Fourier techniques,
and refined on F2 by a full-matrix least-squares method. All
the non-hydrogen atoms were refined anisotropically, and all the
hydrogen atoms were included but not refined. Crystallographic
data are summarized in Table 3.
Crystallography data (excluding structure factors) for the
structures reported in this paper have been deposited with the
Cambridge Crystallographic Data Centre, CCDC 805154 (2a),
CCDC 805155 (2b), 805156 (3b) and 805157 (3c·HCl).† Copies
of these data can be obtained free of charge on application
to the Director, CCDC, 12 Union Road, Cambridge CB2
IEZ, UK (fax: +44-1223-336033; e-mail: deposit@ccdc.ac.uk or
http://www.ccdc.cam.ac.hk).
3a. 1H NMR (CDCl3, 400 MHz): d 3.51 (s, 1H, NH), 4.08 (s,
2H, CH2), 6.55 (d, 2H, Ar–H), 6.75 (t, 1H, Ar–H), 6.82–6.86 (m,
1H, Ar–H), 6.96–7.05 (m, 4H, Ar–H), 7.09–7.16 (m, 4H, Ar–H),
7.22–7.32 (m, 4H, Ar–H), 7.39 (d, 1H, Ar–H), 7.53–7.55 (m, 1H,
Ar–H), 7.61 (s, 1H, NH).
3b. 1H NMR (CDCl3, 400 MHz): d 2.16 (s, 6H, o-Me), 2.23
(s, 3H, p-Me), 2.75 (brs, 1H, NH), 3.88 (s, 2H, CH2), 6.81 (s, 2H,
Ar–H), 6.85–6.95 (m, 2H, Ar–H), 7.03–7.10 (m, 5H, Ar–H), 7.21
(d, 2H, Ar–H), 7.27 (m, 2H, Ar–H), 7.34 (d, 1H, Ar–H), 7.51 (d,
1H, Ar–H), 8.02 (s, 1H, NH).
XAFS data collection. The X-ray absorption data at the Ti
K-edge of the sample were measured in the fluorescent mode with
Lytle fluorescence detector on beam line BL14W1 of the Shanghai
Synchrotron Radiation Facility (SSRF), China. The station was
operated with a double crystal monochromator, Si(111), detuned
to 40% intensity to minimize the presence of higher harmonics.
All measurements were done in transmission or fluorescent mode
using ion chambers filled with a mixture of He and N2 to have
an X-ray absorbance of 20% in the first and 80% in the second
chamber. Data processing and analysis were performed using the
program ATHENA.16 All fits to the EXAFS data were performed
using the program ARTEMIS.16
3c. 1H NMR (CDCl3, 400 MHz): d 1.15 (d, 12H, CH(CH3)2),
2.90 (brs, 1H, NH), 3.21 (hept, 2H, CH(CH3)2), 3.86 (s, 2H, CH2),
6.85–6.88 (m, 1H, Ar–H), 6.96–7.04 (m, 2H, Ar–H), 7.07–7.29 (m,
12H, Ar–H), 7.52 (d, 1H, Ar–H), 7.70 (brs, 1H, NH).
4a. To a stirred suspension of TiCl4 (1.0 mL, 1.0 mmol) in
10 mL of toluene was added 3a (0.38 g, 1.0 mmol) in 20 mL
toluene dropwise at - 78 ◦C. Stirring was maintained for 12 h
at room temperature, and the precipitate was filtered and washed
by toluene and hexane sequentially, affording 4a (0.40 g, 80%) as
brown red powder. 4a 1H NMR (CDCl3, 400 MHz): d 4.19 (s, 2H,
CH2), 6.31 (d, 1H, Ar–H), 6.79 (t, 1H, Ar–H), 6.96 (d, 1H, Ar–
H), 7.09–7.18 (m, 13H, Ar–H), 7.47 (d, 1H, Ar–H), 7.85 (d, 1H,
Ar–H). IR (KBr): n = 2851, 1714, 1578, 1464, 1376, 1303, 1262,
1157, 726 cm-1. Anal. Calc. for C25H20N2SCl2Ti: C, 60.14; H, 4.04;
N, 5.61; Found: C, 60.23; H, 4.09; N, 5.54.
Ethylene polymerization. A 100 mL flask was equipped with
an ethylene inlet, a magnetic stirrer, and a vacuum line. The
flask was filled with 30 mL of freshly distilled toluene, MAO
(10 wt% in toluene) was added, and the flask was placed in a
bath at the desired polymerization temperature for 10 min. The
polymerization reaction was started by adding a toluene solution
of the catalyst precursor (0.010 mmol) with a syringe. Then the
solvent toluene was added to make the total volume of the solution
50 mL. The polymerization was carried out for the desired time and
then quenched with 3% HCl in ethanol (250 mL). The precipitated
4b. This complex was prepared as described above for 4a,
starting from 3b (0.21 g, 0.5 mmol), and TiCl4 (0.5 mL, 0.5 mmol).
Workup afforded 4b (0.21 g, 78%) as orange red powder. 1H NMR
(CDCl3, 400 MHz): d 2.01 (s, 6H, o-Me), 2.18 (s, 3H, p-Me), 4.86
(s, 2H, CH2), 6.48 (s, 1H, Ar–H), 6.70 (s, 2H, Ar–H), 6.86–7.23 (m,
7734 | Dalton Trans., 2011, 40, 7730–7736
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The Royal Society of Chemistry 2011
©

Table 3 Summary of crystallographic data for 2b, 2c, 3b, 3c·HCl
2b
2c
3b
3c·HCl
Formula
fw
T/K
C28H26N2S
422.57
293(2)
C31H32N2S
464.65
293(2)
C28H28N2S
424.58
293(2)
C31H35ClN2S
503.12
293(2)
Cryst syst
Space group
Monoclinic
C2/c
35.541(8)
8.540(2)
16.126(4)
90
108.397(4)
90
4644.6(19)
8
1.209
0.157
1792
0.15 ¥ 0.12 ¥ 0.10
2.42–25.01
9343/4089
[R(int) = 0.0984]
4089/0/287
0.752
R1 = 0.1565
wR2 = 0.0794
0.144 and -0.169
Monoclinic
P21/c
14.352(6)
38.303(15
10.056(4)
90
107.106(6)
90
5284(34)
8
Monoclinic
P21/n
15.068(6)
7.717(3)
20.796(9)
90
99.169(6)
90
2387.3(17)
4
Monoclinic
P21/n
11.802(5)
10.335(5)
23.884(11)
90
103.704(7)
90
2830(2)
˚
a/A
˚
b/A
˚
c/A
a (◦)
b (◦)
g (◦)
3
˚
V/A
Z
4
D
calc/Mg m-3
1.168
0.143
1984
1.181
0.153
904
1.181
0.230
1072
m/mm-1
F(000)
Cryst size/mm
0.20 ¥ 0.10 ¥ 0.10
1.48–27.01
25507/11211
[R(int) = 0.0828]
11211/0/629
0.753
R1 = 0.1767
wR2 = 0.1310
0.315 and -0.254
0.20 ¥ 0.18 ¥ 0.16
1.56–26.99
11132/5115
[R(int) = 0.0648]
5115/0/291
0.967
R1 = 0.0914
wR2 = 0.1740
0.558 and -0.337
0.16 ¥ 0.12 ¥ 0.08
1.76–26.01
12465/5508
[R(int) = 0.0836]
5508/0/332
0.872
R1 = 0.1496
wR2 = 0.1650
0.467 and -0.245
2q range (◦)
no. of reflns collected/unique
no. of data/restraints/params
goodness of fit on F2
Final R indices [I > 2s(I)]a
-3
˚
lgst diff peak and hole/e A
ꢀ
ꢀ
ꢀ
a R1 = ꢀFo| - |Fcꢀ/ |Fo|; wR2 = [ w(|Fo2| - |Fc2|)2/ w|Fo2|2]1/2
.
polymer was filtered and then dried overnight in a vacuum oven
at 80 ◦C.
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This work was supported by the Shanghai Science and Technology
Committee (08DZ2270500, 08DJ1400103), Shanghai Leading
Academic Discipline Project (B108), the National Basic Research
Program of China (2009CB825300, 2010DFA41160), and the
National Science Foundation of China (21001112). The authors
thank beamline BL14W1 (Shanghai Synchrotron Radiation Fa-
cility) for providing the beam time.
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