Effect of ligand substituents in olefin polymerisation by half-sandwich titanium complexes containing monoanionic iminoimidazolidide ligands-MAO catalyst systems

Article abstract of DOI:10.1039/c1dt10467e

Various half-sandwich titanium complexes containing iminoimidazolidide ligands, CpTiCl₂[1,3-R₂(CH₂N)₂CN] (1a-d) [R = Ph (a), 2,6-Me₂C₆H₃ (b), cyclohexyl (c), ^tBu (d)], have been employed as the catalyst precursors for ethylene polymerisation, syndiospecific styrene polymerisation, and copolymerisation of ethylene with 1-hexene in the presence of MAO cocatalyst; 1d showed the highest catalytic activity for ethylene polymerisation whereas 1b showed the highest activity for syndiospecific styrene polymerisation.

Full text of DOI:10.1039/c1dt10467e

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PAPER
Effect of ligand substituents in olefin polymerisation by half-sandwich
titanium complexes containing monoanionic iminoimidazolidide
ligands–MAO catalyst systems†
Kotohiro Nomura,*a,b Hiroya Fukuda,b Shohei Katao,b Michiya Fujiki,b Hyun Joon Kim,c Dong-Hyun Kimc and
Shu Zhanga
Received 18th March 2011, Accepted 11th May 2011
DOI: 10.1039/c1dt10467e
Various half-sandwich titanium complexes containing iminoimidazolidide ligands,
CpTiCl2[1,3-R2(CH2N)2C N] (1a–d) [R = Ph (a), 2,6-Me2C6H3 (b), cyclohexyl (c), tBu (d)], have been
employed as the catalyst precursors for ethylene polymerisation, syndiospecific styrene polymerisation,
and copolymerisation of ethylene with 1-hexene in the presence of MAO cocatalyst; 1d showed the
highest catalytic activity for ethylene polymerisation whereas 1b showed the highest activity for
syndiospecific styrene polymerisation.
analogue also incorporated 1-hexene in copolymerisation of
Introduction
ethylene with 1-hexene,7 we thus have an interest to explore the
Design of efficient molecular catalysts for precise olefin polymeri-
details for preparation of various iminoimidazolidide analogues
sation attracts considerable attention in the field of organometallic
with different substituents as promising candidates as catalyst pre-
chemistry, catalysis, and of polymer chemistry.1–4 Half-sandwich
cursors in olefin polymerisation. Moreover, we previously reported
that CpTiCl2(N CtBu2) showed much higher catalytic activity
than CpTiCl2(N CPh2) in ethylene polymerisation in the pres-
ence of methylaluminoxane (MAO).11 Therefore, in this report,
we present syntheses and structural analyses of half-sandwich
titanium complexes containing various iminoimidazolidide lig-
ands with different substituents, CpTiCl2[1,3-R2(CH2N)2C N]
[R = Ph (1a), 2,6-Me2C6H3 (1b), cyclohexyl (1c), Bu (1d)], and
explored results for ethylene polymerisation, syndiospecific styrene
polymerisation, and ethylene/1-hexene copolymerisation.
titanium complexes containing anionic donor ligands of type,
Cp¢TiX2(Y) (Cp¢ = cyclopentadienyl group, X = halogen, alkyl,
Y = aryloxo, ketimide, phosphinimide etc.), are promising
candidates,3,5–10 especially in terms of syntheses of new polymers
by ethylene copolymerisations as demonstrated by the aryloxo
and the ketimide analogues.3b–d,5,8–10 We already demonstrated that
an efficient catalyst for the desired ethylene copolymerisations
with a-olefin,5b–d styrene,8,9 norbornene10 can be tuned by the
ligand modifications (Cp¢, Y).3b,c It was also demonstrated that the
anionic ligand (Y) strongly affects the comonomer incorporation
and the copolymerisation behavior.3b,c
It has been reported by Kretschmer and Hessen7 that
CpTi(CH2Ph)2[1,3-(2,6-Me2C6H3)2(CH2N)2C N] exhibited high
catalytic activity for ethylene polymerisation in the presence of
both B(C6F5)3 and partially hydrolysed tris(isobutyl)-aluminium,
and the activity was higher than those by the ketimide analogue,
CpTi(CH2Ph)2(N CtBu2), and the phosphinimide analogue,
CpTi(CH2Ph)2(N PtBu2). Since the above iminoimidazolidide
t
Results and Discussion
1. Syntheses, structural analyses of Cp-iminoimidazolidide
titanium(IV) dichloride complexes
Half-sandwich titanium complexes containing alkyl substituted
iminoimidazolidide ligands, CpTiCl2[1,3-R2(CH2N)2C N] (1c,d)
t
[R = cyclohexyl (c), Bu (d)], could be prepared from CpTiCl3
according to the previous report for syntheses of the aryl analogues
[R = Ph (a), 2,6-Me2C6H3 (b)],7 and the complexes (1c,d) were
identified by NMR spectra and elemental analysis. The cor-
responding lithium iminoimidazolidide, [1,3-R2(CH2N)2C N]Li
were prepared by the analogous procedure in the previous report
(Scheme 1).7,12
Yellow microcrystals of 1b–d that are suitable for X-ray
crystallographic analyses were grown from the chilled CH2Cl2
solution (-30 ◦C) layered by n-hexane, and their structures
are shown in Fig. 1. The selected bond distances and an-
gles are summarised in Table 1.13 These complexes fold a
aDepartment of Chemistry, Tokyo Metropolitan University, 1-1 Minami
Osawa, Hachioiji, Tokyo, 192-0397, Japan. E-mail: ktnomura@tmu.ac.jp;
Fax: +81-42-677-2547; Tel: +82-42-677-2547
bGraduate School of Materials Science, Nara Institute of Science and
Technology, 8916-5 Takayama, Ikoma, Nara, 630-0101, Japan
cKorea Institute of Industrial Technology, 35-3 Hongcheon-ri, Ipjang-myeon,
Seobuk-gu, Cheonan-si, Chungnam, 331-825, Korea
† Electronic supplementary information (ESI) available: Structural anal-
ysis reports including CIF files for CpTiCl2[1,3-R2(CH2N)2C N] [R =
t
2,6-Me2C6H3 (1b), cyclohexyl (1c), Bu (1d)]. CCDC reference numbers
817925-827927. For ESI and crystallographic data in CIF or other
electronic format see DOI: 10.1039/c1dt10467e
7842 | Dalton Trans., 2011, 40, 7842–7849
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Scheme 1 Syntheses of CpTiCl2[1,3-R2(CH2N)2C N] (1c,d) [R = cyclo-
hexyl (c), tBu (d)].
distorted tetrahedral geometry around the titanium, and the
˚
Ti–N bond distances [1.7650(16)–1.7918(17) A] are appar-
ently shorter than those in (1,3-Me2C5H3)TiCl2[N(2,6-Me2C6H3)-
14a
˚
(SiMe3)] [1.898(2) A], Cp*TiCl2[N(Me)(cyclohexyl)] [1.870(3)
14b
11
˚
˚
A], and in Cp*TiCl2(N CPh2) [1.827(2) A], and the distance
˚
is shorter than the estimated value (2.02 A) for a titanium-nitrogen
single bond according to Pauling’s covalent radii.15 These results
thus suggest that both the titanium and nitrogen form s-bonds in
addition to p-donation from the nitrogen, and the p-donation from
nitrogen to Ti would be strong compared to the complexes exem-
plified above.11,14 In contrast, the distances are close or longer than
those in half-sandwich titanium complexes containing imidazolin-
2-iminato ligands, CpTiCl2[N-1,3-R2N2C3H2], [1.765(3), 1.768(2),
t
i
i
6f
˚
and 1.778(2) A in R = Bu, Pr, 2,6- Pr2C6H3, respectively].
˚
˚
Moreover, the distances in 1b–d [1.7860(16) A in 1b, 1.7650(16) A
in 1c, 1.7823(18) A in 1d] are slightly or apparently shorter than
1a [1.7918(17) A] reported previously, suggesting that the bond
˚
7
˚
distances were influenced by the ligand substituents (R).
The Ti–Cl bond distances and the Cl(1)–Ti(1)–Cl(2) bond
◦
˚
angles in 1a–d [2.2902(7)–2.3124(5) A; 100.27(3)–105.14(2) ,
respectively] are close to those in the imidazolin-2-iminato
˚
analogues, CpTiCl2[N-1,3-R2N2C3H2] [2.2977(8)–2.3253(6) A:
◦
99.22(2)–100.49(3) ; R = Bu, iPr, 2,6-iPr2C6H3, respectively].6f In
one case, the angle in 1c [105.14(2)◦] is larger than the others,
although we have no appropriate explanation for the observed
difference at this moment. The Ti(1)–N(1)–C(6) bond angles
in 1a–c [152.92(16)–163.23(14)◦] are smaller than ◦those in the
imidazolin-2-iminato analogues [163.3(1)–175.8(1) ],6f and the
angle in 1d [172.08(17)◦] is larger than 1a–c and somewh◦at close to
that in CpTiCl2[N-1,3-(2,6-iPr2C6H3)N2C3H2] [175.8(1) ].6f Short
t
˚
Ti–N bond distance [1.7823(18) A] and almost linear Ti–N–C
bond angle [172.08(17)◦] are indicative of efficient ligand-to-metal
p-donation, as previously observed by Cp*TiCl2(O-2,6-iPr2C6H3)
◦
Fig.
1
Ortep drawings for CpTiCl2[1,3-R2(CH2N)2C N] [R
=
˚
[Ti–O: 1.772 A and Ti–O–C 173.0(3) ] which exhibit remarkable
t
2,6-Me2C6H3 (b, top), cyclohexyl (c, middle), Bu (d, bottom)]. Thermal
ellipsoids are drawn at 50% probability level, and H atoms were omitted
for clarity. The structural analysis reports including CIF files are shown in
the Electronic Supplementary Information (ESI†).13
catalytic activity in ethylene (co)polymerisation in the presence of
methylaluminoxane (MAO).5
2. Ethylene polymerisation and ethylene/1-hexene
copolymerisation using Cp-iminoimidazolidide titanium(IV)
dichloride complexes–MAO catalyst systems
white solid (d-MAO) prepared by removing AlMe3 and toluene
from the commercially available samples (PMAO-S, 6.8 wt% in
toluene, Tosoh Finechem Co.) was chosen in this study, because
it was effective in the preparation of high molecular weight
ethylene/a-olefin copolymers with unimodal molecular weight
Ethylene polymerisations using CpTiCl2[1,3-R2(CH2N)2C N]
t
[R = Ph (1a), 2,6-Me2C6H3 (1b), cyclohexyl (1c), Bu (1d)] were
conducted in toluene at 25 ◦C in the presence of MAO. MAO
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◦
Table 1 Selected bond distances (A), angles ( ) for CpTiCl2[1,3-R2(CH2N)2C N] [R = Ph (1a),7 2,6-Me2C6H3 (1b), cyclohexyl (1c), tBu (1d)]a
˚
CpTiCl2[1,3-R2(CH2N)2C N]
R = Ph (1a)b
R = 2,6-Me2C6H3) (1b)
R = cyclohexyl (1c)
R = tert-Bu (1d)
˚
Bond Distances (A)
Ti(1)–Cl(1), Ti(1)–Cl(2)
Ti(1)–N(1)
2.3045(7); 2.2902(7)
1.7918(17)
2.3088(7); 2.3106(7)
1.7860(15)
2.3093(7); 2.3177(7)
1.7650(16)
2.3124(5)c
1.7823(18)
N(1)–C(6)
1.305(3)
1.308(3)
1.325(2)
N(1)–C(4) 1.320(3)
2.340(3); 2.403(2)
N(2)–C(4) 1.354(2)
N(2)–C(5) 1.446(2)
C(5)–C(5)* 1.501(2)
Ti(1)–C(1), Ti(1)–C(3)
N(2)–C(6), N(3)–C(6)
N(2)–C(7), N(3)–C(8)
C(7)–C(8)
2.331(2); 2.360(2)
1.359(3); 1.362(3)
1.465(3); 1.467(4)
1.517(4)
2.406(2); 2.354(2)
1.362(3); 1.353(3)
1.468(3); 1.465(3)
1.531(4)
2.392(3); 2.350(2)
1.354(2); 1.346(2)
1.468(2); 1.480(3)
1.533(3)
Bond Angles (◦)
Cl(1)–Ti(1)–Cl(2)
Ti(1)–N(1)–C(6)
Cl(1)–Ti(1)–N(1),
Cl(2)–Ti(1)–N(1)
100.90(2)
152.92(16)
104.92(6); 105.55(6)
100.27(3)
163.23(14)
101.84(7); 106.80(6)
105.14(2)
159.82(15)
102.60(6); 103.64(6)
Cl(1)–Ti(1)–Cl(1)* 100.74(2)
Ti(1)–N(1)–C(4) 172.08(17)
104.20(3)c
a The structure reports including CIF file are shown in the Electronic Supplementary Information (ESI).13 b Cited from reference 7. c Symmetry operator,
see Fig. 1(bottom).
Table 2 Ethylene polymerisation by CpTiCl2[1,3-R2(CH2N)2C N] (1a–
Table 3 summarises results for ethylene/1-hexene copolymerisa-
tions using 1a–d–MAO catalyst systems under the optimised Al/Ti
molar ratios (for 1c,d, conducted for the ethylene polymerisation).
Copolymerisation by 1a,b were performed under various Al/Ti
molar ratios, because, as described below, the resultant polymers
possessed broad molecular weight distributions. The results us-
ing Cp*TiCl2(O-2,6-iPr2C6H3),5d CpTiCl2(N CtBu2)6e conducted
under similar conditions are also added for comparison.
t
d) [R = Ph (a), 2,6-Me2C6H3 (b), cyclohexyl (c), Bu (d)]–MAO catalyst
systemsa,b
Run
Complex (mmol)
MAO/mmol
Yield/mg
Activityc
1
2
3
4
5
6
7
8
1a (0.1)
3.0
3.0
0.5
1.0
2.0
3.0
4.0
5.0
0.05
0.10
0.25
0.5
1.0
2.0
2.0
3.0
43
37
26
34
53
69
53
54
69
106
84
113
37
34
9.5
16
2580
2220
780
1b (0.1)
1c (0.2)
1c (0.2)
1020
1590
2070
1590
1620
8280
12720
10080
6780
2220
2040
290
1c (0.2)
The catalytic activity in the copolymerisation increased in
the order: 30 kg-polymer/mol-Ti·h (1c) < 150 (1a) < 300
(1b) < 4620 (1d). In all cases, the observed activities in the
copolymerisations were lower than those in the ethylene homo
polymerisation. Moreover, the resultant polymers by 1a–c–MAO
catalyst systems possessed broad molecular weight distributions
(Mw/Mn = 4.39–68.3), suggesting that the several catalytically
active species were present in the reaction mixture under these
conditions. The fact by 1b–MAO catalyst system was somewhat
different from that conducted by using CpTi(CH2Ph)2[1,3-(2,6-
Me2C6H3)2(CH2N)2C N] – B(C6F5)3 catalyst system, which ex-
hibited high catalytic activity [3960 kg–polymer/mol-Ti·h; condi-
tions: Ti 10 mmol, B(C6F5)3 1.1 equiv., toluene 210 mL, 1-hexene
20 mL (0.71 M), ethylene 5 bar, 80 ◦C] to afford poly(ethylene-
co-1-hexene) with unimodal molecular weight distribution [Mw =
1.81 ¥ 105, Mw/Mn = 2.0, 1-hexene content 18 wt% (6.8 mol%)].
Although we are not sure why the resultant polymers prepared by
1b possessed broad molecular weight distributions, it seems likely
that 1b decomposed gradually by excessive MAO (runs 21–24).
1c (0.2)
1c (0.2)
1c (0.2)
9
1d (0.05)
1d (0.05)
1d (0.05)
1d (0.10)
1d (0.10)
1d (0.10)
CpTiCl3 (0.2)
CpTiCl3 (0.2)
10
11
12
13
14
15
16
490
a Conditions: toluene 30 mL, ethylene 6 atm, d-MAO (prepared by
removing toluene and AlMe3 from ordinary MAO), 25 ◦C, 10 min.
b The resultant polymers were linear polyethylene but GPC analysis in
o-dichlorobenzene vs. polystyrene standards at 140 ◦C failed (insoluble).
c Activity = kg-polymer/mol-Ti·h.
distributions when the Cp*TiCl2(O-2,6-iPr2C6H3) was used as the
catalyst precursor.5b The polymerisations by CpTiCl3 were also
conducted for comparison. The results are summarised in Table 2.
As expected from the crystallographic analysis results, the tert-
Bu analogue (1d) exhibited exceptionally high catalytic activity
(10080, 12720 kg-PE/mol-Ti·h, runs 10–11) under the optimised
Al/Ti molar ratios; the activity by 1d (under optimised Al/Ti
molar ratio) was much higher than those by 1a–c [2580 (1a),
2220 (1b), 2070 (1c), runs 1,2,6], suggesting that the activity was
affected by the substituent in the iminoimidazolidide ligand (R).
The resultant polymers were insoluble in hot o-dichlorobenzene
Fig.
2
shows 13C NMR spectrum (in 1,2,4-
trichlorobenzene/C6D6 at 110 ◦C) of the resultant poly(ethylene-
co-1-hexene) prepared by 1d–MAO catalyst system (run 26)
and Table 4 summarises the triad sequence distribution, the
dyads, rE, rH, and rE·rH values on the basis of microstructure
analysis estimated by the 13C NMR spectrum. The data by
Cp*TiCl2(O-2,6-iPr2C6H3),5d CpTiCl2(N CtBu2)6e conducted
under similar conditions are also added for comparison.
It is clear that the copolymerisation by 1d–MAO catalyst system
proceeded in a random manner (1-hexene incorporations were
random in these catalyses) due to that the rE·rH values being close
to 1. The rE value was 4.95, and the value was larger than that
by the Cp*-aryloxo analogue (2.70, run 27)5d but close to the
◦
for ordinary conditions by GPC analysis (140 C), probably due
to the resultant polymer possessing ultra high molecular weight.16
The information concerning the catalytically-active species was
thus not obtained.
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Table 3 Copolymerisation of ethylene with 1-hexene by CpTiCl2[1,3-R2(CH2N)2C N] (1a–d) [R = Ph (a), 2,6-Me2C6H3 (b), cyclohexyl (c), tBu (d)]–MAO
catalyst systemsa
e
e
run/mg
complex (mmol)
MAO/mmol
yield
activityd
Mn ¥10-3
Mw/Mn
content.f/mol (%)
17
18
19
20
21
22
23
24
25
26
27
28
1a (3.0)
1.0
2.0
3.0
4.0
2.0
3.0
4.0
5.0
3.0
0.10
2.1
3.0
33
50
74
70
81
100
94
61
21
70
100
150
140
240
300
280
180
2.09
1.79
1.16
1.05
68.0
66.2
62.5
26.7
17.3
947
68.3
55.6
54.0
49.5
5.12
4.39
4.50
8.38g
12.6
1.72
1.82
2.40
1a (3.0)
1a (3.0)
1a (3.0)
1b (2.0)
1b (2.0)
1b (2.0)
1b (2.0)
1c (4.0)
30
1d (0.1)
77
1267
190
4620
181000
114000
28.6
37.3
26.9
Cp*-OArb (0.07)
Cp-Ketc (0.01)
295
704
a Conditions: toluene 25 mL, 1-hexene 5 mL (1.34 M), ethylene 6 atm, d-MAO (prepared by removing toluene and AlMe3 from ordinary MAO), 25 ◦C,
10 min. b Cited from reference 5d, Cp*-OAr = Cp*TiCl2(O-2,6-iPr2C6H3), conditions: 1-hexene 1.45 M, toluene and 1-hexene total 55 mL. c Cited from
reference 6e, Cp-Ket = CpTiCl2(N CtBu2), conditions: 1-hexene 1.00 M, toluene and 1-hexene total 55 mL. d Activity = kg-polymer/mol-Ti·h. e GPC
data in o-dichlorobenzene vs. polystyrene standards. f 1-Hexene content (mol%) estimated by 13C NMR spectra. g Low molecular weight shoulder was
observed in small amount in the GPC trace.
Table 4 Monomer sequence distributions of poly(ethylene-co-1-hexene)s prepared by copolymerisation of ethylene (E) with 1-hexene (H) by CpTiCl2[1,3-
tBu2(CH2N)2C N] (1d)–MAO catalyst systema
Triad sequence distributiond (%)
Dyade
Content.c/
mol (%)
f
g
g
Run Complex
EEE EEH+HEE HEH
EHE
HHE+EHH HHH EE
EH+HE HH rE·rH
rE
rH
26
27
28
1d
28.6
26.9
37.4
41.4
34.5
18.9
24.4
30.7
29.1
5.6
7.9
14.6
14.8
20.5
23.9
13.8
5.2
11.8
—
1.2
1.7
53.6
49.9
33.5
39.5
46.4
58.9
6.9
3.8
7.6
0.94
0.35
0.29
4.95 0.19
4.5 0.08
2.70 0.11
Cp-Ketb
Cp*-OArc
a For detailed polymerisation conditions, see Table 3. b Cited from reference 5d. c Cited from reference 6e. d 1-Hexene content (mol%) estimated by 13C
NMR spectra. e Determined by 13C NMR spectra. f [EE] = [EEE]+1/2[EEH+HEE], [EH] = [HEH]+[EHE]+1/2{[EEH+HEE]+[HHE+EHH]}, [HH] =
[HHH]+1/2[HHE+EHH]. g rE¥rH = 4[EE][HH]/[EH+HE]2. hrE = [H]0/[E]0¥2[EE]/[EH+HE], rH = [E]0/[H]0¥2[HH]/[EH+HE], [E]0 and [H]0 are the
initial monomer concentrations.
3. Syndiospecific styrene polymerisation using
Cp-iminoimidazolidide titanium(IV) dichloride complexes–MAO
catalyst systems
We previously demonstrated in the Cp¢-aryloxo,9a,17 –amide14b and
the pyrazolato18 analogues that efficient catalyst precursors for
the syndiospecific styrene polymerisation can be tuned from the
efficient catalyst precursors for the ethylene polymerisation by
ligand modification. For example, Cp*TiCl2(O-2,6-iPr2C6H3) is
the effective catalyst precursor for the ethylene polymerisation,
whereas (tert-BuC5H4)TiCl2(O-2,6-iPr2C6H3) is the effective cat-
alyst precursor for the syndiospecific styrene polymerisation.9a
We thus conducted styrene polymerisation using CpTiCl2[1,3-
R2(CH2N)2C N] [R = Ph (1a), 2,6-Me2C6H3 (1b), cyclohexyl
(1c), tBu (1d)] in the presence of MAO (at 25 ◦C), and the results
conducted under certain Al/Ti molar ratios are summarised in
Table 5.
Fig. 2 13C NMR spectrum (in 1,2,4-trichlorobenzene/C6D6 at 110 ◦C)
of the resultant poly(ethylene-co-1-hexene) prepared by 1d–MAO catalyst
system (run 26).
In contrast to the result in the ethylene polymerisation, 1d
showed the lowest catalytic activity. The activity increased in the
Cp¢-ketimide analogue (4.5, run 28).6e These results thus suggest
that 1d showed rather efficient 1-hexene incorporations, and that
a precise modification of the anionic donor ligand plays an
important role for the copolymerisation to proceed with uniform
catalytically active species as well as with moderate comonomer
incorporation.
order: 50 sPS/mol-Ti·h (1d, R = tert-Bu) < 80 (1a, R = Ph) < 200
(1c, R = cyclohexyl) < 260 (1b, R = 2,6-Me2C6H3). Although
the observed activities by 1b were much lower than those by
the CpTiCl2(O-2,6-iPr2C6H3) or CpTiCl3–MAO catalysts,17 the
activity was affected by the substituents in the iminoimidazolidide
ligand. The resultant polymers were syndiotactic polystyrene
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t
Table 5 Syndiospecific styrene polymerisation by CpTiCl2[1,3-R2(CH2N)2C N] (1a–d) [R = Ph (a), 2,6-Me2C6H3 (b), cyclohexyl (c), Bu (d)]–MAO
catalyst systemsa
d
d
Run
Complex (mmol)
MAO/mmol
Yieldb/mg
Activityc
Mn ¥10-4
Mw/Mn
29
30
31
32
1a (5.0)
1b (3.0)
1c (2.0)
1d (2.0)
3.0
3.0
3.0
0.10
69
130
67
80
1.95
2.28
1.90
4.06
2.84
2.58
2.27
4.09
260
200
50
17
a Conditions: toluene 1 mL, styrene 10 mL, d-MAO (prepared by removing toluene and AlMe3 from ordinary MAO), 25 ◦C, 10 min. b Polymer yield based
on acetone insoluble fraction (syndiotactic polystyrene, sPS). c Activity = kg-sPS/mol-Ti·h. d GPC data in o-dichlorobenzene vs. polystyrene standards.
(sPS, as acetone insoluble fraction) in all cases. The molecular
weight distribution in the resultant polymer prepared by 1d–MAO
catalyst was broad (Mw/Mn = 4.09, run 32), whereas the polymers
prepared by 1a–c–MAO catalyst systems possessed unimodal
molecular weight distributions (Mw/Mn = 2.27–2.84, runs 29–31),
suggesting the catalytically active species in the reaction mixture
were uniform. The results presented here are in unique contrast
to those observed in the ethylene/1-hexene copolymerisations.
The results emphasise the unique characteristics demonstrated by
the half-sandwich titanium complexes containing anionic donor
ligands of this type, showing that efficient catalysts for the desired
(co)polymerisation can be tuned by the ligand modification.3b–d
On the basis of the results in Table 5, preliminary experiments
for copolymerisation of ethylene with styrene using 1b,c which
showed moderate catalytic activities for syndiospecific styrene
polymerisation were conducted [conditions: toluene 25 mL,
styrene 5 mL (1.45 M), ethylene 4 atm, d-MAO 3.0 mmol,
25 ◦C, 10 min; 1b 5.0 mmol, 1c 10.0 mmol].20 However, 1c showed
low catalytic activity (10 kg-polymer/mol-Ti·h), and 1b showed
moderate activity (120 kg-polymer/mol-Ti·h) affording a mixture
of polyethylene and poly(ethylene-co-styrene) estimated by both
the 1H NMR spectrum and differential scanning calorimetric
(DSC) thermogram [melting temperature (Tm): 124.8. 42.5 ◦C]
with bimodal molecular weight distributions [Mn = 1.28 ¥ 106,
Mw/Mn = 1.49; Mn = 2.30 ¥ 104, Mw/Mn = 1.88; by GPC
data in o-dichlorobenzene at 140 ◦C vs. polystyrene standards].
The fact is also different from that conducted by the diben-
zyl analogue, CpTi(CH2Ph)2[1,3-(2,6-Me2C6H3)2(CH2N)2C N]
– B(C6F5)3 catalyst system [conditions: Ti 10 mmol, B(C6F5)3
1.1 equiv., toluene 210 mL, styrene 20 mL (0.76 M), ethylene
5 bar, 80 ◦C], which afforded poly(ethylene-co-styrene) with
unimodal molecular weight distribution [1960 kg–polymer/mol-
Ti·h, Mw = 1.79 ¥ 105, Mw/Mn = 2.1, styrene content 10 wt% (2.9
mol%)].7 Although we do not have an appropriate explanation
for the observed difference, it seems likely that at least two
catalytically-active species were generated from 1b in the presence
of MAO. We are still exploring the (co)polymerisation behaviour
under various conditions including syntheses of various Cp¢-
iminoimidazolidide titanium(IV) dichloride analogues, especially
with different cyclopentadienyl fragments.
syndiospecific styrene polymerisation, and copolymerisation of
ethylene with 1-hexene in the presence of MAO cocatalyst.
Complexes 1c,d have been prepared and identified, and structures
for 1b–d were determined by X-ray crystallography. The tert-
butyl analogue (1d), CpTiCl2[1,3-tBu2(CH2N)2C N], showed
exceptionally high catalytic activity for ethylene polymerisation
in the presence of MAO, and 1d was also found be effective
for ethylene/1-hexene copolymerisation affording poly(ethylene-
co-1-hexene) with efficient 1-hexene incorporation. Although
1d showed low catalytic activity for syndiospecific styrene
polymerisation, the diemethylphenyl analogue, CpTiCl2[1,3-(2,6-
Me2C6H3)2(CH2N)2C N] (1b), showed higher catalytic activity,
suggesting that an effective catalyst precursor for the desired
polymerisation can be tuned by the ligand modification, as demon-
strated previously.3b–d On the basis of these results described above,
we will now focus on preparing a series of half-sandwich titanium
complexes containing iminoimidazolidide ligands especially with
different cyclopentadienyl fragments (substituents on Cp¢). The
detailed results will be reported in the near future.
Experimental Section
General Procedures
All experiments were carried out under a nitrogen atmosphere
in a Vacuum Atmospheres drybox unless otherwise specified. All
chemicals used were of reagent grade and were purified by the
standard purification procedures. Anhydrous grade tetrahydrofu-
ran, diethyl ether, n-hexane, dichloromethane, and toluene (Kanto
Chemical Co., Inc.) were transferred into bottles containing
˚
˚
molecular sieves (mixture of 3 A 1/16 and 4 A 1/8, and 13X
1/16) under a nitrogen stream in the drybox and were used with-
out further purification. CpTiCl2[1,3-Ph2(CH2N)2C N] (1a) and
CpTiCl2[1,3-(2,6-Me2C6H3)2(CH2N)2C N] (1b) were prepared
according to the reported procedure.7 Ethylene for polymerisation
was of polymerisation grade (purity >99.9%, Sumitomo Seika Co.,
Ltd.) and was used as received. Elemental analyses were performed
by using a PE2400II Series (Perkin-Elmer Co.).
All 1H and 13C NMR spectra were recorded on a JEOL
JNMLA400 spectrometer (399.65 MHz, 1H; 100.40 MHz, 13C). All
deuterated NMR solvents were stored over molecular sieves under
a nitrogen atmosphere, and all chemical shifts are given in ppm
and are referenced to residual solvent peaks. Molecular weights
and molecular weight distributions for the polyethylene samples
were measured by gel permeation chromatography (Tosoh HLC-
8121GPC/HT) using a RI-8022 detector (for high temperature,
Tosoh Co.) with a polystyrene gel column (TSK gel GMHHR-H
HT ¥ 2, 30 cm ¥ 7.8 mm i.d.), ranging from <102 to <2.8 ¥ 108
Concluding Remarks
A series of half-sandwich titanium complexes containing iminoim-
idazolidide ligands, CpTiCl2[1,3-R2(CH2N)2C N] (1a–d) [R =
Ph (a), 2,6-Me2C6H3 (b), cyclohexyl (c), tBu (d)], have been
employed as the catalyst precursors for ethylene polymerisation,
7846 | Dalton Trans., 2011, 40, 7842–7849
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Table 6 Crystal data and collection parameters of CpTiCl2[1,3-R2(CH2N)2C N] [R = 2,6-Me2C6H3 (1b), cyclohexyl (1c), tBu (1d)]
1b
1c
1d
Formula
C24H27Cl2N3Ti
476.30
C20H31Cl2N3Ti
432.29
C16H27Cl2N3Ti
380.22
Formula weight
Crystal color, habit
Crystal size/mm
Crystal system
Space group
yellow, block
0.45 ¥ 0.45 ¥ 0.12
Triclinic
yellow, block
0.32 ¥ 0.20 ¥ 0.18
Orthorhombic
P212121 (#19)
9.0816(3)
yellow, block
0.48 ¥ 0.16 ¥ 0.16
Orthorhombic
Pnma (#62)
12.8021(3)
¯
P1 (#2)
˚
a/A
8.2728(3)
9.4651(4)
16.8992(6)
80.281(1)
82.631(1)
62.550(1)
1155.48(7)
2
˚
b/A
12.7130(5)
18.7394(7)
17.5227(4)
8.7440(2)
˚
c/A
a (◦)
b (◦)
g (◦)
3
˚
V/A
2163.54(13)
4
1.327
912.00
123
6.513
21288
4941
1961.53(8)
4
1.287
800.00
123
7.086
18393
2310
Z value
Dc/g cm-3
1.369
496.00
123
6.173
11559
5250
295
0.0333
0.0997
1.112
F000
T/K
m(Mo-Ka)/cm-1
No. of Reflections Measured
No. of Observations (I > 2.00s(I))
No. of Variables
R1(I > 2.00s(I))
wR2 (I > 2.00s(I))
Goodness of fit
237
107
0.0352
0.0854
1.072
0.0369
0.0993
1.070
aThe structure reports including CIF files are shown in the Supporting Information.13
◦
MW) at 140 C using o-dichlorobenzene containing 0.05 wt/v%
2,6-di-tert-butyl-p-cresol. The molecular weight was calculated
by a standard procedure based on the calibration with standard
polystyrene samples.
(CDCl3): d 26.0 (NCHC2H4C3H6), 30.9 (NCHC2H4C3H6), 40.1
(NCH2CH2N), 53.6 (NCHC5H10), 115.4 (C5H5), 154.2 (N2CN).
Anal. Calcd. for C20H31Cl2N3Ti: C, 55.57; H, 7.23; N, 9.72%.
Found: C, 55.57; H, 7.45; N, 9.53%.
Synthesis of HN = 2,5-(cyclo-C6H13)2C3N2H4, and HN =
Synthesis of CpTiCl2(N = 2,5-tBu2C3N2H4) (1d)
2,5-tBu2C3N2H4
The synthetic procedure of 1d was the same as that for 1a except
that Li(N = 2,5-tBu2C3N2H4) (165 mg, 0.81 mmol) was used
in place of Li(N = 2,5-Cy2C3N2H4). Yield 189 mg (64.2%). H
NMR (C6D6): d 1.22 (s, 18H, NCMe3), 2.44 (s, 4H, NCH2CH2N),
6.45 (s, 1H, C5H5). 13C NMR (CDCl3): d 29.1 (NCMe3), 42.7
(NCH2CH2N), 55.8 (NCMe3), 116.4 (C5H5), 157.3 (CNH). Anal.
Calcd. for C16H27Cl2N3Ti: C, 50.55; H, 7.16; N, 11.05%. Found:
C, 50.60; H, 6.98; N, 11.07%.
Syntheses of HN = 2,5-(cyclo-C6H13)2C3N2H4, and HN = 2,5-
tBu2C3N2H4 were performed by the analogous procedure (shown
in Scheme 1) reported previously12 for syntheses of HN = 2,5-
Ph2C3N2H4, HN = 2,5-(2,6-Me2C6H3)2C3N2H4, except that tert-
butyl amine or cyclohexylamine was used in place of aniline
or 2,6-dimethylaniline. Total yields: 26.0% [HN = 2,5-(cyclo-
C6H13)2C3N2H4], 9.9% [HN = 2,5-tBu2C3N2H4]. HN = 2,5-(cyclo-
1
1
C6H13)2C3N2H4: H NMR (CDCl3): d 1.89 (m, 22H, NC6H11),
3.16 (s, 4H, NCH2CH2N), 3.55 (s, 1H, CNH). 13C NMR
(CDCl3): d 26.2 (NCHC2H4C3H6), 30.0 (NCHC2H4C3H6), 40.6
(NCH2CH2N), 53.1 (NCHC5H10), 160.3 (CNH). HN = 2,5-
Crystallographic analysis
Yellow block microcrystals which are suited for the crystallo-
graphic analysis were grown from the chilled CH2Cl2 solution
layered by n-hexane (-30 ◦C). All measurements were made
on a Rigaku RAXIS-RAPID Imaging Plate diffractometer with
graphite monochromated Mo-Ka radiation. The selected crystal
collection parameters are listed in Table 6, and the detailed results
were described in the reports in the Electronic Supplementary
Information (ESI†). All structures were solved by direct methods20
and expanded using Fourier techniques (except for 1b),21 and the
non-hydrogen atoms were refined anisotropically. Hydrogen atoms
were included but not refined. All calculations were performed
using the Crystal Structure22 crystallographic software package
except for refinement, which was performed using SHELXL-
97.23 Detailed analysis data including the collection parameters,
CIF files, and the structure reports are shown in the Electronic
Supplementary Information (ESI†). CCDC reference numbers for
1
tBu2C3N2H4: H NMR (CDCl3): d 1.36 (s, 18H, NCMe3), 3.09
(s, 4H, NCH2CH2N), 4.84 (s, 1H, CNH). 13C NMR (CDCl3): d
28.1 (NCMe3), 42.8 (NCH2CH2N), 53.4 (NCMe3), 162.3 (CNH).
Synthesis of CpTiCl2(N = 2,5-(cyclo-C6H13)2C3N2H4) (1c)
Into a THF solution (10 mL) containing CpTiCl3 (400 mg, 1.83
mmol), Li[N = 2,5-(cyclo-C6H13)2C3N2H4] (470 mg, 1.83 mmol)
was added at -30 ◦C. The reaction mixture was stirred for 3 h at
25 ◦C, and the solution was concentrated, was then extracted by
hot toluene. The toluene extracts were concentrated in vacuo, and
placed in a freezer. Yellow microcrystals were obtained from the
chilled solution (-30 ◦C). Yield 619 mg (77.3%). 1H NMR (C6D6):
d 1.23 (m, 20H, NCHC5H10), 2.58 (s, 4H, NCH2CH2N), 3.96
(t, 2H, J = 11.6 Hz, NCHC5H10), 6.43 (s, 1H, C5H5). 13C NMR
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CpTiCl2[1,3-R2(CH2N)2C N] [R = 2,6-Me2C6H3 (1b), cyclohexyl
(1c), tBu (1d)] are 817925–827927, respectively.
Synth. Catal., 2005, 347, 355; (c) G. J. Domski, J. M. Rose, G. W. Coates,
A. D. Bolig and M. Brookhart, Prog. Polym. Sci., 2007, 32, 30.
2 Special issues, see: (a) Frontiers in Metal-Catalysed Polymerisation
(special issue); ed. J. A. Gladysz, Chem. Rev., 2000, 100(4), 1167;
(b) Metallocene complexes as catalysts for olefin polymerisation (special
issue); ed. H. G. Alt, Coord. Chem. Rev., 2006, 250(1–2), 1; (c) Metal-
catalysed Polymerisation (special issue); ed. B. Milani and C. Claver,
Dalton Trans., 2009, 8769.
3 Reviewing articles, accounts for half-metallocenes, see: (a) D. W.
Stephan, Organometallics, 2005, 24, 2548; (b) K. Nomura, J. Liu,
S. Padmanabhan and B. Kitiyanan, J. Mol. Catal. A: Chem., 2007,
267, 1; (c) K. Nomura, Dalton Trans., 2009, 8811; (d) K. Nomura
and J. Liu, Dalton Trans., in press (web released on March 15, DOI:
10.1039/C1DT10086F). Related references were cited therein.
4 Recent examples for syndiotactic polystyrene and the related chemistry,
see: (a) J. Schellenberg, Prog. Polym. Sci., 2009, 34, 688; (b) Syndiotactic
Polystyrene - Synthesis, Characterization, Processing, and Applications,
J. Schellenberg, Ed., John Wiley & Sons, Inc., New Jersey, 2010.
5 (a) K. Nomura, N. Naga, M. Miki, K. Yanagi and A. Imai,
Organometallics, 1998, 17, 2152; (b) K. Nomura, N. Naga, M. Miki
and K. Yanagi, Macromolecules, 1998, 31, 7588; (c) K. Nomura, K.
Oya, T. Komatsu and Y. Imanishi, Macromolecules, 2000, 33, 3187;
(d) K. Nomura, T. Komatsu and Y. Imanishi, J. Mol. Catal. A: Chem.,
2000, 159, 127.
6 Selected (initial) examples for nonbridged half-sandwich titanium com-
plexes containing mono anionic (monodentate) donor ligands,3c,d(a) D.
W. Stephan, J. C. Stewart, F. Gue´rin, R. E. v. H. Spence, W. Xu and
D. G. Harrison, Organometallics, 1999, 18, 1116; (b) D. W. Stephan,
J. C. Stewart, S. J. Brown, J. W. Swabey and Q. Wang, EP881233 A1
(1998); (c) J. McMeeking, X. Gao, R. E. v. H. Spence, S. J. Brown and
D. Jerermic, USP 6114481 (2000); (d) D. W. Stephan, J. C. Stewart, F.
Gue´rin, S. Courtenay, J. Kickham, E. Hollink, C. Beddie, A. Hoskin,
T. Graham, P. Wei, R. E. v. H. Spence, W. Xu, L. Koch, X. Gao
and D. G. Harrison, Organometallics, 2003, 22, 1937; (e) K. Nomura,
K. Fujita and M. Fujiki, J. Mol. Catal. A: Chem., 2004, 220, 133;
(f) A. R. Dias, M. T. Duarte, A. C. Fernandes, S. Fernandes, M.
M. Marques, A. M. Martins, J. F. da Silva and S. S. Rodrigues, J.
Organomet. Chem., 2004, 689, 203; (g) C. Beddie, E. Hollink, P. Wei,
J. Gauld and D. W. Stephan, Organometallics, 2004, 23, 5240; (h) E.
G. Ijpeij, P. J. H. Windmuller, H. J. Arts, F. Van Der Burgt, G. H. J.
van Doremaele and M. A. Zuideveld, WO, 2005090418, 2005; (i) H.
Ishino, S. Takemoto, K. Hirata, Y. Kanaizuka, M. Hidai, M. Nabika, Y.
Seki, T. Miyatake and N. Suzuki, Organometallics, 2004, 23, 454; (j) M.
Tamm, S. Randoll, E. Herdtweck, N. Kleigrewe, G. Kehr, G. Erker and
B. Rieger, Dalton Trans., 2006, 459; (k) E. G. Ijpeij, M. A. Zuideveld, H.
J. Arts, F. Van Der Burgt and G. H. J. van Doremaele, WO, 2007031295,
2007.
Ethylene polymerisation, ethylene/1-hexene copolymerisation
Ethylene polymerisations were conducted in toluene by using a
100 mL scale autoclave. Solvent (29.0 mL) and prescribed amount
of d-MAO white solid, prepared by removing toluene and AlMe3
from commercially available MAO (PMAO-S, Tosoh Finechem
Co.), were charged into the autoclave in the drybox, and the
apparatus was placed under ethylene atmosphere (1 atm). After
the addition of a toluene solution (1.0 mL) containing a prescribed
amount of complex via a syringe, the reaction apparatus was
pressurized to 5 atm (total 6 atm), and the mixture was stirred
magnetically for 10 min. After the above procedure, ethylene was
purged, and the mixture was then poured into MeOH (150 mL)
containing HCl (10 mL). The resultant polymer was collected
on a filter paper by filtration and was adequately washed with
MeOH and then dried in vacuo. Experimental procedures for the
ethylene/1-hexene copolymerisations were the same as those for
the ethylene polymerisations except that a prescribed amount of
1-hexene (5.0 mL) was charged and the total volume of toluene
and 1-hexene was set to 30 mL.
Syndiospecific styrene polymerisation
Styrene (10 mL) and the prescribed amount of MAO solid
were added into the round bottom flask in the drybox at room
temperature (25 ◦C). A toluene solution (1.0 mL) containing the
prescribed amount of complex was then added into the autoclave,
and the mixture was magnetically stirred for 10 min. The mixture
was then taken out from the drybox, and was quickly terminated
by adding EtOH (ca. 3 mL). The mixture was then poured into
EtOH (50 mL) containing HCl (5 mL). The resultant polymer was
collected on filter paper by filtration, and was adequately washed
with EtOH, and was then dried in vacuo. According to the previous
report,9a the resultant polymer mixture was separated into two
fractions, and atactic polystyrene prepared only by MAO itself
was extracted with acetone; syndiotactic polystyrene prepared
by titanium complexes–MAO catalyst system was isolated as the
acetone insoluble fraction.
7 W. P. Kretschmer, C. Dijkhuis, A. Meetsma, B. Hessen and J. H.
Teuben, Chem. Commun., 2002, 608. Catalytic activity for ethylene
polymerisation by CpTi(CH2Ph)2[1,3-(2,6-Me2C6H3)2(CH2N)2C N]
in the presence of B(C6F5)3 and partially hydrolysed tris(isobutyl)-
aluminium [8000 kg-PE/mol-Ti·h; conditions: Ti 10 mmol, B(C6F5)3
1.1 equiv., toluene 210 mL, ethylene
5
bar, 80 ◦C, 15 min].
The activity was higher than those by the ketimide analogue,
CpTi(CH2Ph)2(N CtBu2) (2320 kg-PE/mol-Ti·h), and the phosphin-
imide analogue, CpTi(CH2Ph)2(N PtBu2) (5450 kg-PE/mol-Ti·h)
under the same conditions.
8 (a) K. Nomura, in Syndiotactic Polystyrene - Synthesis, Characteriza-
tion, Processing, and Applications, ed. J. Schellenberg, John Wiley &
Sons, Inc., New Jersey, 2010, p. 60; (b) K. Nomura, Catal. Surv. Asia,
2010, 14, 33.
9 (a) K. Nomura, T. Komatsu and Y. Imanishi, Macromolecules, 2000,
33, 8122; (b) K. Nomura, H. Okumura, T. Komatsu and N. Naga,
Macromolecules, 2002, 35, 5388; (c) H. Zhang and K. Nomura, J.
Am. Chem. Soc., 2005, 127, 9364; (d) H. Zhang and K. Nomura,
Macromolecules, 2006, 39, 5266; (e) H. Zhang, D.-J. Byun and K.
Nomura, Dalton Trans., 2007, 1802.
10 (a) K. Nomura, M. Tsubota and M. Fujiki, Macromolecules, 2003, 36,
3797; (b) W. Wang, T. Tanaka, M. Tsubota, M. Fujiki, S. Yamanaka
and K. Nomura, Adv. Synth. Catal., 2005, 347, 433; (c) K. Nomura, W.
Wang, M. Fujiki and J. Liu, Chem. Commun., 2006, 2659.
11 K. Nomura, J. Yamada, W. Wang and J. Liu, J. Organomet. Chem.,
2007, 692, 4675.
Acknowledgements
The present research is partly supported by Grant-in-Aid for
Scientific Research (B) from the Japan Society for the Promotion
of Science (JSPS, No.21350054). K.N., H.F. and S.Z. express their
thanks to Tosoh Finechem Co. for donating MAO (PMAO-S), and
S.Z. expresses his thanks to the JSPS for a postdoctoral fellowship
(P08361). Part of the present research is also supported by a
grant from the Fundamental R&D Program for Core Technology
of Materials funded by the Ministry of Knowledge Economy,
Republic of Korea. The authors thank Mr. Atsushi Igarashi
(Tokyo Metropolitan University) for his experimental assistance
(polymerisation data by CpTiCl3).
Notes and references
12 L. Toldy, M. Ku¨rti and I. Scha¨fer, Ger. Pat., DE 2916140, 1979 (Egyt
Gyo. Gyar.).
1 (1) Recent selected reviews, see: (a) V. C. Gibson and S. K. Spitzmesser,
Chem. Rev., 2003, 103, 283; (b) P. D. Bolton and P. Mountford, Adv.
7848 | Dalton Trans., 2011, 40, 7842–7849
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13 Structure reports including CIF files for CpTiCl2[1,3-R2(CH2N)2C N]
(1b–d) [R = 2,6-Me2C6H3 (b), cyclohexyl (c), tBu (d)] are shown in the
Electronic Supplementary Information (ESI).
volume was set to 30 mL. According to the previous report,7 the
resultant polymer mixture in the copolymerisation might be separated
into three fractions, and atactic polystyrene which was prepared only
by MAO was extracted with acetone.
14 (a) K. Nomura and K. Fujii, Organometallics, 2002, 21, 3042; (b) K.
Nomura and K. Fujii, Macromolecules, 2003, 36, 2633.
20 SIR92: A. Altomare, G. Cascarano, C. Giacovazzo, A. Guagliardi, M.
Burla, G. Polidori and M. Camalli, J. Appl. Cryst., 1994, 27, 435.
21 DIRDIF99: P. T. Beurskens, G. Admiraal, G. Beurskens, W. P. Bosman,
R. de Gelder, R. Israel and J. M. M. Smits, (1999), The DIRDIF-99
program system, Technical Report of the Crystallography Laboratory,
University of Nijmegen, The Netherlands.
22 (a) CrystalStructure 4.0: Crystal Structure Analysis Package, Rigaku
Corporation (2000-2010). Tokyo 196-8666, Japan.; (b) CrystalStructure
3.8: Crystal Structure Analysis Package, Rigaku and Rigaku Americas
(2000–2007). 9009 New Trails Dr The Woodlands TX 77381 USA.
23 SHELX97: G. M. Sheldrick, Acta Crystallogr., Sect. A: Found.
Crystallogr., 2007, 64, 112.
15 L. Pauling, The Nature of the Chemical Bond, 3rd ed., Cornell
University Press, Ithaca, NY, 1960.
16 Syntheses of ultra high molecular weight polyethyelenes, W. Wang and
K. Nomura, Adv. Synth. Catal., 2006, 348, 743.
17 D-J. Byun, A. Fudo, A. Tanaka, M. Fujiki and K. Nomura, Macro-
molecules, 2004, 37, 5520.
18 K. Nomura, H. Fukuda, S. Katao, M. Fujiki, H.-J. Kim, D.-H. Kim
and I. Saeed, Macromolecules, 2011, 44, 1986.
19 Experimental procedures for the ethylene/styrene copolymerisations
were the same as those for the ethylene polymerisations except that
a prescribed amount of styrene (5.0 mL) was charged and the total
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The Royal Society of Chemistry 2011
Dalton Trans., 2011, 40, 7842–7849 | 7849
©