Synthesis, characterisation and ethylene oligomerization behaviour of N-(2-substituted-5,6,7-trihydroquinolin-8-ylidene)arylaminonickel dichlorides

Article abstract of DOI:10.1039/c0nj00516a

A series of N-(2-substituted-5,6,7-trihydroquinolin-8-ylidene)- arylaminonickel(ii) dichlorides were synthesized by the one-pot stoichiometric reaction of nickel dichloride, 2-chloro- or 2-phenyl-substituted 5,6,7-trihydroquinolin-8-one, and the corresponding anilines. All nickel complexes were characterized by elemental and spectroscopic analysis. The molecular structures of representative nickel complexes, determined by the single-crystal X-ray diffraction, indicate the different coordination numbers around nickel either four with more bulky ligands or five with less bulky ligands. All nickel complexes, activated with ethylaluminium sesquichloride (Et₃Al₂Cl₃), showed high activities (up to 9.5 × 10⁶ g mol^-1 h^-1) in ethylene oligomerization for dimer and trimers. The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2011.

Full text of DOI:10.1039/c0nj00516a

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PAPER
Synthesis, characterisation and ethylene oligomerization behaviour of
N-(2-substituted-5,6,7-trihydroquinolin-8-ylidene)arylaminonickel
dichloridesw
Jiangang Yu,ac Xinquan Hu,b Yanning Zeng,c Liping Zhang,c Caihua Ni,*a
Xiang Haoc and Wen-Hua Sun*c
Received (in Montpellier, France) 2nd July 2010, Accepted 9th September 2010
DOI: 10.1039/c0nj00516a
A series of N-(2-substituted-5,6,7-trihydroquinolin-8-ylidene)-arylaminonickel(II) dichlorides were
synthesized by the one-pot stoichiometric reaction of nickel dichloride, 2-chloro- or 2-phenyl-
substituted 5,6,7-trihydroquinolin-8-one, and the corresponding anilines. All nickel complexes
were characterized by elemental and spectroscopic analysis. The molecular structures of
representative nickel complexes, determined by the single-crystal X-ray diffraction, indicate the
different coordination numbers around nickel either four with more bulky ligands or five with less
bulky ligands. All nickel complexes, activated with ethylaluminium sesquichloride (Et3Al2Cl3),
showed high activities (up to 9.5 Â 106 g molÀ1
h
À1) in ethylene oligomerization for dimer and
trimers.
In general, N,N-bidentate Ni(II) complexes are more attractive
Introduction
due to their easy syntheses and better catalytic performances.
Within N,N-bidentate Ni(II) complexes, the 2-iminopyridinyl
nickel halides (D) showed good activities in ethylene poly-
merization,5a,b and their derivatives showed activities for both
oligomerization and polymerization.5d,e However, there is no
research on the fused-cycloalkanonylpyridine for such
2-iminopyridines as ligands. In this work, the 2-chloro- and
2-phenyl-substituted 5,6,7-trihydroquinolin-8-ones12 are used
to form N-(2-substituted-5,6,7-trihydroquinolin-8-ylidene)-
arylaminonickel dichlorides. The molecular structures of
representative complexes are determined by single-crystal
X-ray crystallography analysis, and indicate that the five-
coordinated number is preferred for nickel complexes bearing
N-(2-chloro-5,6,7-trihydroquinolin-8-ylidene)arylamines,
whereas the four-coordinated number is found for nickel
complexes ligating N-(2-phenyl-5,6,7-trihydroquinolin-8-
ylidene)arylamines. All nickel catalysts are highly active in
ethylene oligomerization in the presence of ethylaluminium
sesquichloride (Et3Al2Cl3). Herein the synthesis and character-
isation of the title nickel complexes are reported along with
their performance in ethylene oligomerisation.
Ethylene oligomerization is one of most important industrial
processes for producing linear alpha-olefins, in which a well-
known process is the Shell Higher Olefin Process (SHOP)
employing the nickel catalyst (A) (Scheme 1).1 The interest
in nickel catalysts for ethylene reactivity was resurrected with
the observation that highly active ethylene polymerization
catalyst of diiminonickel complexes (B)2 and self-activating
catalyst of neutral salicylaldiminonickel complexes (C).3 In the
past decade, papers of nickel complexes acting as catalysts in
ethylene oligomerization and polymerization have mush-
roomed with extensive works of nickel complexes bearing
bidentate ligands such as N^N,4,5 N^P,6 N^O,7 P^O,8 and
tridentate ligands such as N^N^N,4e,9 N^N^O,4e,5e,10 N^P^N.11
Scheme 1 Model catalysts.
a School of Chemical and Material Engineering, Jiangnan University,
Wuxi 214122, China. E-mail: nicaihua2000@163.com
Results and discussion
b College of Chemical Engineering and Materials Science,
Zhejiang University of Technology, Hangzhou 310014, China
c Key Laboratory of Engineering Plastics, Beijing National Laboratory
for Molecular Sciences, Institute of Chemistry, Chinese Academy of
Sciences, Beijing 100190, China. E-mail: whsun@iccas.ac.cn;
Fax: +86-10-62618239
Synthesis and characterisation
The reaction of 2-chloro/phenyl-5,6,7-trihydroquinolin-8-one
with anilines gave two compounds due to partial migration
of the double bonding of Schiff-base into inner cyclic 4,5-
dihydroquinolin-8-arylamines, therefore the stepwise procedure
w CCDC reference numbers 779268–779271. For crystallographic data
in CIF or other electronic format see DOI: 10.1039/c0nj00516a
c
178 New J. Chem., 2011, 35, 178–183
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Scheme 2 Synthetic procedure of bidentate nickel complexes.
of preparing ligands and then forming nickel complexes is not
suitable for the current work. To overcome the problem in
synthesizing unstable ligands11,13 or forming ligands in low
yields,14 one-pot reaction is an efficient methodology to form
metal complex due to cation-induced assembly. Therefore, the
title nickel complexes are formed in acceptable yields through
the one-pot reactions of 2-chloro- (or phenyl-)5,6,7-trihydro-
quinolin-8-one, the corresponding anilines and NiCl2Á6H2O in
acetic acid (Scheme 2). All complexes were consistent with
their elemental analyses, and their IR spectra with a strong
band in the range 1550–1600 cmÀ1 which can be ascribed to
the stretching vibration of CQN. The unambiguous molecular
structures of Ni2, Ni3, Ni8 and Ni10 are confirmed by single-
crystal X-ray crystallography.
Fig. 1 ORTEP drawing of complex Ni2 with thermal ellipsoids at
30% probability level. Hydrogen atoms have been omitted for clarity.
Molecular structures
Crystals of Ni2, Ni3, Ni8 and Ni10 suitable for single-crystal
X-ray crystallography have been obtained by laying diethyl
ether on their ethanol solution at room temperature. The
molecular structures indicate two kinds of coordination
numbers around nickel atoms. The five-coordination around
nickel atom is observed within complexes Ni2 and Ni3, which
are a chloro-bridged dimer or a monomeric nickel complex
Fig. 2 ORTEP drawing of complex Ni3 with thermal ellipsoids at
30% probability level. Hydrogen atoms have been omitted for clarity.
containing
a coordinated ethanol, respectively. Within
complexes Ni8 and Ni10, they adapt four-coordination numbers
with bidentate ligands and two chlorides. The coordination
numbers are dependent on the steric hindrances associated
with their ligands. The ligands with a bulky aryl group occupy
more space around nickel and induce the lower coordination
numbers for complexes Ni8 and Ni10; the ligands bearing
chloro-substituent form nickel complexes with five-coordination
number, forming the chloro-bridged dimeric Ni2 and monomer
Ni3 having an additional solvent. Such phenomena are
commonly observed within other nickel complexes in the
literature.15 The molecular structures of Ni2, Ni3, Ni8 and
Ni10 are shown in Fig. 1–4, and their selected bond lengths
and angles are listed in Table 1.
Fig. 3 ORTEP drawing of complex Ni8 with thermal ellipsoids at
30% probability level. Hydrogen atoms have been omitted for clarity.
The five-coordinated complexes Ni2 and Ni3 display the
distorted bipyramidal coordination environment around
nickel atom, whereas the four-coordinated complexes Ni8
and Ni10 adopt the distorted tetrahedral sphere. As shown
in Table 1, the ligands embrace nickel atoms stronger in
complexes Ni8 and Ni10 with shorter bond lengths of Ni–N
and larger bond angles of N1–Ni–N2 than the analogous
complexes Ni2 and Ni3 show. Regarding dimeric Ni2,
there is no direct bonding between two nickel atoms with
intramolecular distance 3.481 A, which is quite similar to the
data 3.475 A observed in the analogous di-m-chloro-
bis(2-iminopyridinyl)dinickel dichlorides.16
Ethylene oligomerization
Various alkylaluminiums such as MAO, MMAO, AlEt2Cl and
ethylaluminium sesquichloride (Et3Al2Cl3, EASC) have been
c
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New J. Chem., 2011, 35, 178–183 179

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EASC as cocatalyst exhibits highest activity (entry 4 in
Table 2), which is consistent to its analogues of iminopyridinyl-
nickel catalysts.17 Therefore, the EASC is used as activator for
selecting optimum reaction parameters such as ratios of
aluminium to nickel (entries 4–8 in Table 2), reaction
temperatures (entry 6, entries 9–11 in Table 2) and lifetime
of the active species (entry 6, entries 12–15 in Table 2).
The Ni3/EASC is studied with changing Al/Ni molar ratios
from 200 to 600 (entries 4–8 in Table 2) at 20 1C, shows best
value of 8.7 Â 106 g molÀ1(Ni) hÀ1 with the molar ratio of
Al/Ni = 400 : 1 (entry 6 in Table 2). The molar ratio of
Al/Ni = 400 : 1, both catalytic activity and a-olefin and
butuene selectivity are observed greatest at 20 1C (entry 6 in
Table 2); and the catalytic system behave a lower activity and
worse a-olefin selectivity along with increasing reaction
temperature (entries 9–11 in Table 2), such phenomena were
also observed by other nickel catalysts.4e,9b,18 Prolonging
reaction time (entries 6, 12–13 in Table 2), the activity is
slightly decreased meanwhile the amount of hexenes are
mainly increased. These results indicate no inducing period
of ethylene oligomerization, and the active species are
slowly deactivated. Therefore, other nickel procatalysts are
investigated at 20 1C with the molar ratio of Al/Ni = 400 : 1,
and all catalytic performances are tabulated in Table 3.
Even though the complex Ni2 is dinuclear as a solid, the
active species of all nickel catalysts are generally considered as
their monomeric species. Therefore, two series of active species
are formed regarding to the differences of their ligands with R1
substituent. Two sets of data are comparable on the base of
ligands with R1 substituent (chloro for the nickel complexes
Ni1–Ni5 and Ph for the nickel complexes Ni6–Ni10). Their
activities decrease in the order of 2,6-di(i-Pr) > 2,6-di(Et) >
2,6-di(Me) > 2,6-di(Et)-4-Me > 2,4,6-tri(Me) with R1 = Cl;
meanwhile, with R1 = Ph, the activities decrease in the order
of 2,6-di(i-Pr) > 2,6-di(Et) > 2,6-di(Me), and 2,6-di(Et)-4-Me >
2,4,6-tri(Me). Such phenomena are consistent with
observations in literature that bulky alkyl substituents help
solubility of procatalysts for better activity.18b,19 Interestingly,
catalysts Ni4 and Ni9 (R2 and R3 = Me) which showed the
Fig. 4 ORTEP drawing of complex Ni10 with thermal ellipsoids at
30% probability level. Hydrogen atoms have been omitted for clarity.
Table 1 Selected bond lengths (A) and angles (1) for complexes Ni2,
Ni3, Ni8 and Ni10
Ni2
Ni3
Ni8
Ni10
˚
Bond lengths/A
Ni1–N1
Ni1–N2
Ni1–Cl1
Ni1–Cl2
N2–C9
N2–C10
N1–C1
N1–C5
Ni1–O1
2.077(5)
2.030(4)
2.2766(16) 2.278(3)
2.3789(17) 2.324(3)
1.289(7)
1.464(7)
1.327(7)
1.352(7)
—
2.077(9)
2.054(8)
2.044(6)
2.012(6)
2.202(3)
2.234(2)
1.293(9)
1.451(9)
1.367(10)
1.362(10)
—
2.018(5)
2.011(5)
2.2166(17)
2.1992(18)
1.276(7)
1.440(7)
1.345(8)
1.360(8)
—
1.292(13)
1.460(13)
1.327(13)
1.379(12)
2.038(8)
Bond angles (1)
N2–Ni1–N1
N2–Ni1–Cl1
N1–Ni1–Cl1
N2–Ni1–Cl2
N1–Ni1–Cl2
79.10(18) 79.8(3)
110.73(14) 102.5(3)
81.6(3) 82.0(2)
106.79(19) 104.65(15)
93.77(13)
97.11(14)
171.25(13) 89.6(2)
89.4(3)
137.8(2)
110.2(2)
96.68(19)
123.12(14)
112.34(14)
100.04(14)
107.6(3)
Cl1–Ni1–Cl2 94.95(6)
149.20(12) 117.29(13) 126.21(7)
O1–Ni1–N2
O1–Ni1–N1
O1–Ni1–Cl1
—
—
—
99.0(3)
176.1(3)
87.3(2)
—
—
—
—
—
—
evaluated as activators to activate the complex Ni3 in ethylene
oligomerization (entries 1–4 in Table 2). The system employing
Table 2 Ethylene oligomerization by Ni3 with various alkylaluminiumsa
Product distribution (%)c
P
P
C4/
a-C4/C4
C6/
Entry
Cocatalyst
Al/Ni
T/1C
t/min
Activityb
1
2
3
4
5
6
7
8
MAO
1000
1000
200
200
300
400
500
600
400
400
400
400
400
400
400
20
20
20
20
20
20
20
20
40
60
80
20
20
20
20
30
30
30
30
30
30
30
30
30
30
30
10
20
40
50
0.31
0.93
0.94
4.54
5.1
8.7
5.9
5.4
7.6
6.5
5.8
9.5
9.0
5.8
4.7
87.1
86.9
84.3
92.5
89.4
89.6
88.0
85.1
77.9
81.2
73.9
91.5
86.7
87.5
86.8
98.0
89.0
84.3
>99.0
97.1
>99.0
>99.0
>99.0
94.2
87.4
76.7
12.9
13.1
15.7
7.5
MMAO
AlEt2Cl
EASC
EASC
EASC
EASC
EASC
EASC
EASC
EASC
EASC
EASC
EASC
EASC
10.6
10.4
12.0
14.9
22.1
18.8
26.1
8.5
9
10
11
12
13
14
15
>99.0
>99.0
>99.0
>99.0
13.3
12.5
13.2
P
a
b
c
Reaction conditions: 5 mmol of Ni; 10 atm of ethylene; 100 mL of toluene. Activity, 106 g molÀ1(Ni) hÀ1
total amount of oligomers.
.
Determined by GC. donates the
c
180 New J. Chem., 2011, 35, 178–183
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Table 3 Oligomerization of ethylene with all nickel procatalysts/
EASCa
(nCQN), 1488, 1409, 1341, 1239, 1123, 1028, 866, 783, 675,
616, 502, 403. Anal. calcd for C17H17Cl3N2Ni(414): C, 49.27;
H, 4.14; N, 6.76%. Found: C, 49.21; H, 4.41; N, 6.49%.
MS-ESI: calcd for C17H17Cl3N2Ni m/z 411.9, found m/z
377.0 (M À Cl)+.
Product distribution (%)c
P
P
Entry
Cat.
Activityb
C4/
a-C4/C4
C6/
[2,6-Diethyl-N-(2-chloro-5,6,7-trihydroquinolin-8-ylidene)
phenylamino]nickel(II) dichloride (Ni2) was obtained as green
powder in 55.0% yield. IR (KBr; cmÀ1): 3049, 2963, 2930,
2875, 1581 (nCQN), 1449, 1262, 1237, 1190, 1156, 1124, 864,
817, 781, 676, 641, 521. Anal. calcd for C19H21Cl3N2Ni(442):
C, 51.58; H, 4.78; N, 6.33%. Found: C, 51.53; H, 5.12; N,
6.05%. MS-ESI: calcd for C19H21Cl3N2Ni m/z 440.0, found
m/z 405.0 (M À Cl)+.
1
2
3
4
5
6
7
8
9
10
Ni1
Ni2
Ni3
Ni4
Ni5
Ni6
Ni7
Ni8
Ni9
Ni10
3.7
7.1
8.7
2.4
2.5
3.1
3.4
4.1
2.5
4.0
88.5
87.0
89.6
79.3
89.1
84.5
84.5
85.8
79.5
87.7
98.0
90.1
>99.0
>99.0
94.4
90.2
87.1
85.6
89.7
11.5
13.0
10.4
20.7
10.9
15.5
15.5
14.2
20.5
12.3
83.1
a
[2,6-Bis(1-methylethyl)-N-(2-chloro-5,6,7-trihydroquinolin-
8-ylidene)phenylamino]nickel(II) dichloride (Ni3) was obtained as
green powder in 62.9% yield. IR (KBr; cmÀ1): 3350, 2961,
2927, 2867, 1618, 1581 (nCQN), 1453, 1268, 1238, 1189, 1127,
1038, 928, 877, 816, 779, 550. Anal. calcd for
C21H25Cl3N2Ni(470): C, 53.61; H, 5.36; N, 5.95%. Found:
C, 53.25; H, 5.21; N, 6.03%. MS-ESI: calcd for
C21H25Cl3N2Ni m/z 468.0, found m/z 433.0 (M À Cl)+.
[2,4,6-Trimethyl-N-(2-chloro-5,6,7-trihydroquinolin-8-ylidene)
phenylamino]nickel(II) dichloride (Ni4) was obtained as green
powder in 65.2.0% yield. IR (KBr; cmÀ1): 2923, 1575
(nCQN), 1412, 1235, 1210, 1122, 1035, 1011, 817, 680, 562,
505. Anal. calcd for C18H19Cl3N2Ni(428): C, 50.46; H, 4.47;
N, 6.54%. Found: C, 50.34; H, 4.76; N, 6.91%. MS-ESI: calcd
for C18H19Cl3N2Ni m/z 426.0, found m/z 391.0 (M À Cl)+.
[2,6-Diethyl-4-methyl-N-(2-chloro-5,6,7-trihydroquinolin-
Reaction conditions: 5 mmol of Ni; Al/Ni = 400; 10 atm of ethylene;
30 min; 20 1C; 100 mL of toluene. Activity, 106 g molÀ1(Ni) hÀ1
.
b
P
c
Determined by GC.
donates the total amount of oligomers.
lowest activities with producing more hexene. This phenomena
were caused by the various substituents of R1 and R2. As
shown in Table 3, the activities by Ni6–Ni10 (R1 = Ph, entries
6–10 in Table 3) were much smaller than those by Ni1–Ni5
(R1 = Cl, entries 1–5 in Table 3) due to steric influence of R1
around nickel centre.20
Experimental
General considerations
All manipulations of air and/or moisture sensitive compounds
were performed under nitrogen atmosphere using standard
Schlenk techniques. All solvents were routinely purified and
distilled before use. Methylaluminoxane (MAO, 1.46 M
solution in toluene) and modified methylaluminoxane
(MMAO, 1.93 M in heptane, 3A) were purchased from Akzo
Nobel Corp. Diethylaluminium chloride (Et2AlCl2, 0.79 M in
toluene) and ethylaluminium sesquinochroride (EASC,
0.87 M in toluene) were purchased from Beijing Yansan
Petrochemical Co. Elemental analysis is conducted on a Flash
EA 1112 microanalyzer. IR spectra are recorded on a
Perkin-Elmer System 2000 FT-IR spectrometer using KBr
discs in the range 4000–400 cmÀ1. Gas chromatography
(GC) analysis was performed with a VARIAN CP-3800 gas
chromatograph equipped with a flame ionization detector and
a 30 m (0.2 mm i.d., 0.25 mm film thickness).
8-ylidene)phenylamino]nickel(II)
dichloride
(Ni5)
was
obtained as green powder in 71.0% yield. IR (KBr; cmÀ1):
2956, 2933, 2872, 2854, 1626, 1578 (nCQN), 1444, 1341, 1243,
1142, 1121, 922, 858, 646, 501. Anal. calcd for
C20H23Cl3N2Ni(456): C, 52.63; H, 5.08; N, 6.14%. Found:
C, 52.38; H, 5.29; N, 6.02%. MS-ESI: calcd for
C20H23Cl3N2Ni m/z 454.0, found m/z 419.0 (M À Cl)+.
[2,6-Dimethyl-N-(2-phenyl-5,6,7-trihydroquinolin-8-ylidene)
phenylamino]nickel(II) dichloride (Ni6) was obtained as green
powder in 60.5% yield. IR (KBr; cmÀ1): 3272, 2928, 1558
(nCQN), 1401, 1341, 1162, 1122, 1034, 1009, 815, 763, 679,
614, 482. Anal. calcd for C23H22Cl2N2Ni(456): C, 60.58; H,
4.86; N, 6.14%. Found: 60.76; H, 5.02; N, 6.33%. MS-ESI:
calcd for C23H22Cl2N2Ni m/z 454.0, found m/z 419.0
(M À Cl)+.
[2,6-Diethyl-N-(2-phenyl-5,6,7-trihydroquinolin-8-ylidene)
phenylamino]nickel(II) dichloride (Ni7) was obtained as green
powder in 66.9% yield. IR (KBr; cmÀ1): 3272, 2933, 1555
(nCQN), 1400, 1341, 1166, 1122, 1034, 1009, 679, 614, 494.
Anal. calcd for C25H26Cl2N2Ni(484): C, 62.03; H, 5.41; N,
5.79%. Found: 62.21; H, 5.64; N, 5.91%. MS-ESI: calcd for
C25H26Cl2N2Ni m/z 482.0, found m/z 447.1 (M À Cl)+.
[2,6-Bis(1-methylethyl)-N-(2-phenyl-5,6,7-trihydroquinolin-
Synthesis and characterisation of complexes Ni1–Ni10
All nickel complexes are prepared in the same manner. In
typically synthesizing the complex Ni1, the mixture of
2-chloro-5,6,7-trihydroquinolin-8-one (1.0 mmol), 2,6-di-
methylaniline (1.0 mmol) and NiCl2Á6H2O (1.0 mmol) in
glacial acetic acid (10 mL) is refluxed for 3 h. Acid was
removed under reduced pressure, and the residue was
dissolved in 10 mL methanol. Unreacted NiCl2 was removed
by filtration. 50 mL of diethyl ether was added to precipitate
Ni1. After filtrated and washed with diethyl ether (3 Â 5 mL),
the collected solid was dried under vacuum.
8-ylidene)phenylamino]nickel(II)
dichloride
(Ni8)
was
obtained as green powder in 71.0% yield. IR (KBr; cmÀ1):
3358, 2969, 1557 (nCQN), 1406, 1341, 1027, 762, 677, 616,
508, 403. Anal. calcd for C27H30Cl2N2Ni(442): C, 63.32; H,
5.90; N, 5.47%. Found: C, 63.63; H, 5.97; N, 5.54%. MS-ESI:
calcd for C27H30Cl2N2Ni m/z 510.1, found m/z 475.1.1
(M À Cl)+.
[2,6-Dimethyl-N-(2-chloro-5,6,7-trihydroquinolin-8-ylidene)
phenylamino]nickel(II) dichloride (Ni1) was obtained as green
powder in 51.1% yield. IR (KBr; cmÀ1): 3345, 2931, 1567
c
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Table 4 Crystal data and structure refinement for Ni2, Ni3ÁCH2CH3OH, Ni8 and Ni10
2Ni2
Ni3ÁCH2CH3OH
Ni8
Ni10
Empirical formula
Formula weight
T/K
C38H42Cl6N4Ni2
884.88
173(2)
C23H31Cl3N2NiO
516.56
173(2)
C27H30Cl2N2Ni
512.14
293(2)
C26H28Cl2N2Ni
498.11
173(2)
Wavelength/A
Crystal system
Space group
a/A
b/A
c/A
0.71073
Monoclinic
P21/n
9.4118(19)
18.517(4)
11.063(2)
90
0.71073
Monoclinic
P21/c
11.597(2)
17.402(4)
12.326(3)
90
0.71073
Orthorhombic
Pbca
15.896(3)
16.770(3)
18.790(4)
90
0.71073
Monoclinic
C2/c
31.488(6)
10.033(2)
15.549(3)
90
a (1)
b (1)
93.02(3)
90
1925.3(2)
2
1.526
95.83(3)
90
2450.9(9)
4
1.400
90
90
102.20(3)
90
4801.2(17)
8
1.378
g (1)
V/A3
5009.0(18)
8
1.358
1.005
2144
Z
Dcalcd/g cmÀ3
m/mmÀ1
F(000)
1.428
912
1.136
1080
1.047
2080
Crystal size/mm
y range [1]
Limiting indices
0.30 Â 0.20 Â 0.04
2.15–27.47
À12 r h r 11
À24 r k r 19
À14 r l r 14
15 557
4403 (0.0672)
262
99.8%
0.30 Â 0.13 Â 0.08
1. 78–27.42
À15 r h r 12
À22 r k r 22
À12 r l r 15
19 496
5525 (0.0983)
303
99.1%
0.20 Â 0.24 Â 0.10
2.07–27.44
À18 r h r 20
À21 r h r 17
À24 r h r 24
37 551
5709(0.0906)
289
99.8%
0.17 Â 0.13 Â 0.07
2.13–25.50
À38 r h r 38
À12 r k r 12
À18 r l r 18
27 177
4466(0.0755)
327
99.9%
No. of rflns collected
No. unique rflns [R(int)]
No. of params
Completeness to y [%]
Goodness of fit on F2
1.347
1.412
1.463
1.377
P
Final R indices [I > 2 (I)]
R indices (all data)
R1 = 0.0845
wR2 = 0.1972
R1 = 0.0966
wR2 = 0.2036
0.683 and À0.829
R1 = 0.1587
wR2 = 0.3174
R1 = 0.1804
wR2 = 0.3330
0.630 and À0.620
R1 = 0.1399
wR2 = 0.2849
R1 = 0.1515
wR2 = 0.2953
0.559 and À0.871
R1 = 0.0908
wR2 = 0.1570
R1 = 0.0959
wR2 = 0.1591
0.400 and À0.327
Largest diff peak and hole/e AÀ3
[2,4,6-Trimethyl-N-(2-phenyl-5,6,7-trihydroquinolin-8-ylidene)-
phenylamino]nickel(II) dichloride (Ni9) was obtained as green
powder in 78.0% yield. IR (KBr; cmÀ1): 2247, 2927, 1566
(nCQN), 1406, 1342, 1214, 1124, 1034, 1010, 681, 615, 480.
Anal. calcd for C24H24Cl2N2Ni(470): C, 61.32; H, 5.15; N,
5.96%. Found: C, 61.44; H, 5.39; N, 6.20%. MS-ESI: calcd for
C24H24Cl2N2Ni m/z 468.0, found m/z 433.1 (M À Cl)+.
[2,6-Diethyl-4-methyl-N-(2-phenyl-5,6,7-trihydroquinolin-
8-ylidene)phenylamino]nickel(II) dichloride (Ni10) was
obtained as green powder in 81.6% yield. IR (KBr; cmÀ1):
3305, 2601, 1567 (nCQN), 1417, 1344, 1234, 1120, 1033, 764,
682, 504. Anal. calcd for C26H28Cl2N2Ni(498): C, 62.69, H,
5.67; N, 5.62%. Found: C, 62.76, H, 5.54; N, 5.69%. MS-ESI:
calcd for C26H28Cl2N2Ni m/z 496.1, found m/z 461.1
(M À Cl)+.
period of time, the reaction was stopped with ceasing the
ethylene inputting. The autoclave was cooled in an ice-water
bath, and then the pressure was released. 2 mL the reaction
solution was collected and terminated by addition of 4 mL
10% aqueous hydrogen chloride. The organic was collected
and analyzed by gas chromatography (GC) to determine the
composition and mass distribution of the oligomers. The
remaining reaction solution was quenched with 5% hydrogen
chloride ethanol.
X-Ray crystallographic studies
Single crystals of Ni2, Ni3ÁCH2CH3OH, Ni8 and Ni10 suitable
for X-ray diffraction analysis were obtained by laying diethyl
ether on their ethanol solution at room temperature. With
graphite-monochromatic Mo Ka radiation (k = 0.71073 A) at
173(2) K, cell parameters were obtained by global refinement
of the positions of all collected reflections. Intensities
were corrected for Lorentz and polarization effects and
empirical absorption. The structures were solved by direct
methods and refined by full-matrix least squares on F2.
All hydrogen atoms were placed in calculated positions.
Structure solution and refinement were performed by using
the SHELXL-97 package.21 Details of the X-ray structure
determinations and refinements are provided in Table 4.
Crystallographic data have been deposited with the
Cambridge Crystallographic Data Centre, CCDC 779268
(Ni2), 779269 (Ni3ÁCH2CH3OH), 779270 (Ni8) and 779271
(Ni10). For crystallographic data in CIF or other electronic
format see DOI: 10.1039/c0nj00516a
General procedure for ethylene oligomerization at 10 atm of
ethylene pressure
Ethylene oligomerization was performed in a stainless steel
autoclave (300 mL capacity) equipped with gas ballast through
a solenoid clave for continuous feeding of ethylene at constant
pressure. 50 mL of toluene was added into the autoclave under
ethylene atmosphere. The catalyst was dissolved in 20 mL
toluene in a Schlenk tube with stirring. When the desired
reaction temperature was reached, the catalyst dissolved in
20 mL toluene, the desired amount of cocatalyst and the
remained toluene (total volume was 100 mL) were added
in turn by syringes. Ethylene at the desired pressure was
introduced to start the reaction. After stirred for the desired
c
182 New J. Chem., 2011, 35, 178–183
This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2011

View Article Online
(c) T. Hu, L.-M. Tang, X.-F. Li, Y.-S. Li and N.-H. Hu,
Organometallics, 2005, 24, 2628–2632; (d) J. Hou, W.-H. Sun,
D. Zhang, L. Chen, W. Li, D. Zhao and H. Song, J. Mol. Catal.
A: Chem., 2005, 231, 221–233; (e) Q. Shi, S. Zhang, F. Chang,
P. Hao and W.-H. Sun, C. R. Chim., 2007, 10, 1200–1208;
(f) A. Kermagoret and P. Braunstein, Dalton Trans., 2008,
1564–1573.
Conclusions
The molecular structures of nickel complexes revealed a
four-coordination number around nickel with 2-phenyl
substituted ligands, and five-coordination number around
nickel with 2-chloro substituted ligands. All title nickel
catalysts perform high activities in ethylene oligomerization
with high selectivity of butenes and hexenes; and catalysts
bearing 2-chloro substituted ligands generally show better
activity than their analogues ligating 2-Ph substituted ligands.
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Acknowledgements
This work was supported by MOST 863 program No.
2009AA033601.
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New J. Chem., 2011, 35, 178–183 183