Synthesis, characterization and ethylene oligomerization behavior of N-(2-alkyl-5,6,7-trihydroquinolin-8-ylidene)arylaminonickel(II) dichlorides

Article abstract of DOI:10.1016/j.ica.2011.12.008

A series of N-(2-alkyl-5,6,7-trihydroquinolin-8-ylidene)arylaminonickel(II) dichloride complexes were synthesized in a one-pot reaction with nickel dichloride. All nickel complexes were characterized by elemental and spectroscopic analysis. The molecular structures of representative nickel complexes, as determined by the single crystal X-ray diffraction, are reported. All nickel complexes, when treated with ethylaluminium sesquichloride (Et ₃Al₂Cl₃), showed high activities (up to 1.1 × 10⁶ g mol^-1 h^-1) for ethylene oligomerization, with good thermal stability at 80 °C at 10 atm ethylene. The influence of the reaction parameters on the catalytic behavior was investigated for these nickel-based systems, including variation of Al/Ni molar ratio and reaction temperature.

Full text of DOI:10.1016/j.ica.2011.12.008

Inorganica Chimica Acta 385 (2012) 21–26
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Inorganica Chimica Acta
journal homepage: www.elsevier.com/locate/ica
Synthesis, characterization and ethylene oligomerization behavior of
N-(2-alkyl-5,6,7-trihydroquinolin-8-ylidene)arylaminonickel(II) dichlorides
c,
b,
Wenbin Chai a,b, Jiangang Yu b, Lin Wang b, Xinquan Hu a, , Carl Redshaw , Wen-Hua Sun
⇑
⇑
⇑
a College of Chemical Engineering and Materials Science, Zhejiang University of Technology, Hangzhou 310014, China
b Key Laboratory of Engineering Plastics, Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
c School of Chemistry, University of East Anglia, Norwich NR4 7TJ, UK
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 2 October 2011
Received in revised form 7 December 2011
Accepted 8 December 2011
Available online 16 December 2011
A series of N-(2-alkyl-5,6,7-trihydroquinolin-8-ylidene)arylaminonickel(II) dichloride complexes were
synthesized in a one-pot reaction with nickel dichloride. All nickel complexes were characterized by ele-
mental and spectroscopic analysis. The molecular structures of representative nickel complexes, as deter-
mined by the single crystal X-ray diffraction, are reported. All nickel complexes, when treated with
ethylaluminium sesquichloride (Et3Al2Cl3), showed high activities (up to 1.1 ꢀ 106 gmolꢁ1 hꢁ1) for ethyl-
ene oligomerization, with good thermal stability at 80 °C at 10 atm ethylene. The influence of the reaction
parameters on the catalytic behavior was investigated for these nickel-based systems, including variation
of Al/Ni molar ratio and reaction temperature.
Keywords:
N-(2-Alkyl-5,6,7-trihydroquinolin-8-
ylidene)arylamine
Ó 2011 Elsevier B.V. All rights reserved.
Nickel(II) complex
Ethylene oligomerization
1. Introduction
ber of recent review articles have covered the progress of nickel
complexes as catalysts for ethylene reactivity [44–47].
a
-Olefins originally manufactured by the Ziegler (Alfen) process
Within the N,N-bidentate Ni(II) family of complexes, the 2-
iminopyridinyl nickel halides showed good activities for both eth-
ylene oligomerization and polymerization [48–51]. Previous work
in our group has reported a fused-cycloalkanylpyridine for such
2-iminopyridine ligation, viz N-(2-chloro-/2-phenyl-5,6,7-trihy-
droquinolin-8-ylidene) arylaminonickel dichlorides [52], which
showed high activity in ethylene oligomerization. The nickel pre-
catalysts bearing N-(5,6,7-trihydroquinolin-8-ylidene)arylamines,
which have no substituent at the ortho-position of the 5,6,7-trihy-
droquinoline, however, performed high activities in ethylene poly-
merization [53]; moreover, their nickel analogs solely showed
ethylene polymerization with verified substituents on the aryl
groups within of N-(5,6,7-trihydroquinolin-8-ylidene)arylamines
[54]. In comparison with the results obtained by nickel pre-cata-
lysts ligated with N-(2-chloro- or 2-phenyl-5,6,7-trihydroquino-
lin-8-ylidene)arylamines, the scope of the nickel complexes
are key intermediates for the synthesis of a wide range of chemical
products. Over the past few decades, the preparation of ethylene
oligomers catalyzed by transition metal complexes has undergone
significant development, especially for those systems based on nick-
el. By the end of the 1970s, nickel complexes had been developed as
catalysts for ethylene oligomerization by Keim et al. [1], which, in
the 1980s, was industrialized in the form of the Shell Higher Olefin
Process (SHOP), and is now a major process for the production of lin-
ear a-olefins via the oligomerization of ethylene [2]. In the 1990s,
Brookhart et al. found that cationic diimino-nickel complexes per-
formed with very good activity during ethylene polymerization
and oligomerization [3–4], and this encouraged further extensive
investigation into new pre-catalysts of other late-transition metal
complexes [5]. Moreover, to improve catalyst performance, efforts
were paid to both the modification of the original ligand set as well
as exploration of new ligand types capable of producing high activity
nickel catalysts, and numerous nickel complexes bearing bidentate
ligands such as N^N [6–13], N^O [14–20], P^N [21–25], P^O [26–
29] and tridentate ligands such as N^P^N [30–32], N^N^O [33–35],
P^N^N [30,36,37], and N^N^N [38–43], have been prepared. A num-
bearing
N-(2-alkyl-5,6,7-trihydroquinolin-8-ylidene)arylamines
are necessarily investigated. Therefore, 2-alkyl-5,6,7-trihydroquin-
olin-8-ones are synthesized, reacted with various anilines and
nickel dihalides to form the corresponding N-(2-alkyl-5,6,7-trihy-
droquinolin-8-ylidene)arylaminonickel dichlorides. The molecular
structures of representative complexes have been determined by
single-crystal X-ray crystallography. Upon activation with ethylal-
uminium sesquichloride (Et3Al2Cl3, EASC), all the nickel pre-cata-
lysts showed good activity towards ethylene oligomerization. The
influence of the reaction parameters on the catalytic performance
has been investigated in detail.
⇑
Corresponding authors. Tel.: +86 10 62557955; fax: +86 10 62618239.
E-mail addresses: xinquan@zjut.edu.cn (X. Hu), Carl.Redshaw@uea.ac.uk
(C. Redshaw), whsun@iccas.ac.cn (W.-H. Sun).
0020-1693/$ - see front matter Ó 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2011.12.008

22
W. Chai et al. / Inorganica Chimica Acta 385 (2012) 21–26
2. Results and discussion
2.1. Synthesis and characterization
Initially, the preparation of the nickel compounds was attempted
by first synthesizing the ligand set (2-methyl/isopropyl-5,6,7-trihy-
droquinolin-8-one plus aniline) followed by subsequent reaction
with the nickel salts; however, this resulted in two compounds,
namely cyclic 4,5-dihydroquinolin-8-arylamines, which were very
unstable. To conquer this problem, a one-pot process involving
2-methyl- or 2-isopropyl-5,6,7-trihydroquinolin-8-one and the cor-
responding aniline together with NiCl2ꢂ6H2O in acetic acid, was
undertaken to synthesize the target nickel complexes (Scheme 1).
All nickel complexes, which were formed in good yield, were
characterized by FT-IR spectroscopy and by elemental analysis, In
the FT-IR spectra, there is a strong band in the range 1550–
1600 cmꢁ1, which can be ascribed to the stretching vibration of
C@N. The molecular structures of complexes Ni1, Ni4 and Ni10
were confirmed by single crystal X-ray crystallography.
Fig. 1. ORTEP drawing of complex Ni1 with thermal ellipsoids at 30% probability
level. Hydrogen atoms have been omitted for clarity.
2.2. X-ray crystallographic studies
Single crystals of the nickel complexes Ni1 and Ni4 suitable for
X-ray diffraction studies were obtained by slow diffusion of diethyl
ether into methanol solution, while crystals of the complex Ni10
were obtained by diffusion of diethyl ether into dichloromethane
solution. The ORTEP diagrams of the molecular structures are
shown in Figs. 1–3. The selected bond lengths and angles are listed
in Table 1.
The five-coordinate complexes Ni1 and Ni4 are best described
as distorted trigonal bipyramidal geometries at nickel, with the
fifth coordination site occupied by the solvent (methanol)
molecule.
Complex Ni10 is a binuclear structure with centrosymmetric
bridging Cl atoms, and the coordination geometry around the nick-
el center can again be described as a distorted trigonal bipyrami-
dal. The ligands with a bulky iPr group occupy more space
around nickel, which for Ni10 creates slight differences in the bond
lengths and bond angles of N1–Ni–N2 from those of Ni1 and Ni4,
and larger bond angles for N2–Ni1–Cl2, Cl1–Ni1–Cl2.
Fig. 2. ORTEP drawing of complex Ni4 with thermal ellipsoids at 30% probability
level. Hydrogen atoms have been omitted for clarity.
2.3. Ethylene oligomerization
In order to find the most suitable co-catalyst, pre-catalyst Ni3
was screened using different co-catalysts such as methylaluminox-
ane (MAO), modified methylaluminoxane (MMAO), diethylalumin-
ium chloride (AlEt2Cl) and ethylaluminium sesquichloride
(Et3Al2Cl3, EASC) at 40 °C (only moderate activity was observed at
20 °C) under 10 atm ethylene (Table 2). In general, good observed
activities were achieved on varying the co-catalysts, with the excep-
tion of the very low activity observed on combination with AlEt2Cl.
However, the benefit of using EASC was evident both in terms of
Fig. 3. ORTEP drawing of complex Ni10 with thermal ellipsoids at 30% probability
level. Hydrogen atoms have been omitted for clarity.
NH2
R1
N
Ni
Cl
R2
R2
R2
NiCl2·6H2O
+
N
catalytic activity and economic considerations, thus EASC was cho-
sen as the co-catalyst for further investigations.
To evaluate the effects of the reaction conditions on the cata-
lytic performance, detailed investigations with complex Ni3 were
carried out using different Al/Ni ratios and reaction temperatures;
results are summarized in Table 3.
For the Ni3/EASC system, on changing of the Al/Ni molar ratio
from 100 to 400 at 40 °C, the highest activity (1.79 ꢀ 105 gmolꢁ1
(Ni)hꢁ1) was achieved with a Al/Ni molar ratio of 200. Furthermore,
R1
N
Cl
CH3COOH
O
R2
R3
R3
Ni1 Ni2 Ni3 Ni4 Ni5 Ni6 Ni7 Ni8 Ni9 Ni10
Me Me Me Me Me iPr iPr iPr iPr iPr
Me Et iPr Me Et Me Et iPr Me Et
R1
R2
R3
H
H
H
Me Me
H
H
H Me Me
Scheme 1. Synthetic procedure of nickel complexes.

W. Chai et al. / Inorganica Chimica Acta 385 (2012) 21–26
23
Table 1
Selected bond lengths (Å) and angles (°) for complexes Ni1, Ni4 and Ni10.
Table 4
Ethylene oligomerization by Ni8/EASC.a
Ni1
Ni4
Ni10
Entry
T (°C)
Al/Ni
Act.b
a
-C4 (%)
C4 (%)
Bond lengths/(Å)
Ni1–N2
Ni1–N1
Bond lengths/
(Å)
Ni1–N2
Ni1–N1
1
2
3
4
5
6
60
80
90
40
40
40
200
200
200
100
200
300
1.03
1.93
1.75
0.33
0.89
0.41
92.2
86.2
82.2
97.1
95.8
96.9
100
100
100
100
100
100
2.032(3)
2.072(3)
2.089(2)
2.025(2)
2.073(2)
2.097(2)
2.041(3)
2.068(3)
2.3063(11)
2.3596(12)
1.339(4)
1.353(5)
1.281(5)
1.437(4)
Ni1–O1
Ni1–Cl1
Ni1–Cl2
N2–C10
N2–C11
N1–C2
2.3039(12) 2.3002(11) Ni1–Cl1
2.3151(14) 2.3130(13) Ni1–Cl2
1.287(4)
1.448(4)
1.335(4)
1.359(4)
1.284(3)
1.445(3)
1.340(3)
1.358(3)
N1–C4
N1–C8
N2–C12
N2–C13
a
Reaction conditions: 5
lmol of Ni; 10 atm ethylene; 30 min.; 100 mL toluene.
Activity: 105 gmolꢁ1 (Ni)hꢁ1
.
b
N1–C6
Bond angles
(°)
Table 5
Ethylene oligomerization by nickel pre-catalysts Ni1–Ni10.a
80.05(11)
93.84(11)
173.18(10) 174.10(8)
110.98(8)
92.44(8)
86.89(8)
111.23(8)
93.81(8)
91.23(8)
137.78(4)
80.10(9)
94.53(9)
Bond angles (°)
N2–Ni1–N1
N2–Ni1–Cl1
N1–Ni1–Cl1
N2–Ni1–Cl2
N1–Ni1–Cl2
Cl1–Ni1–Cl2
80.26(12)
108.45(9)
89.82(9)
105.19(8)
91.71(9)
146.09(4)
N2–Ni1–N1
N2–Ni1–O1
N1–Ni1–O1
N2–Ni1–Cl1
N1–Ni1–Cl1
O1–Ni1–Cl1
N2–Ni1–Cl2
N1–Ni1–Cl2
O1–Ni1–Cl2
Cl1–Ni1–Cl2
Entry
Pre-cat.
Act.b
C4 (%)
a-C4 (%)
112.49(7)
92.47(7)
87.30(7)
107.96(7)
93.21(7)
90.78(7)
139.53(4)
1
2
3
4
5
6
7
8
9
10
Ni1
Ni2
Ni3
Ni4
Ni5
Ni6
Ni7
Ni8
Ni9
Ni10
3.58
3.85
4.3
5.74
11.0
1.61
1.93
3.09
3.87
6.88
100
100
100
100
100
100
100
100
100
100
80.7
79.4
80.3
74.4
63.1
87.4
92.7
86.2
84.1
73.9
Table 2
Selection of a suitable co-catalyst based on Ni3.a
a
Reaction condition: 5
30 min; 100 mL toluene.
lmol of Ni; 10 atm ethylene; EASC, Al/Ni = 20; 80 °C;
b
Activity: 105 gmolꢁ1 (Ni)hꢁ1
.
Entry
Pre-cat.
Co-cat.
Al/Ni
Act.b
C4 (%)
a-C4 (%)
1
2
3
4
Ni3
Ni3
Ni3
Ni3
EASC
MAO
Et2AlCl
MMAO
200
1000
200
1.79
1.48
0.21
1.98
100
100
100
100
91.7
82.9
86.4
64.6
the electronic density, compared to that in our previous systems
[52].
Based on the optimum conditions found for the nickel complex
Ni3 with R1 = Me, the screening conditions of a representative
nickel complex with R1 = iPr (Ni8) were selected. The results are
summarized in Table 4.
1000
a
Reaction conditions: 5
toluene.
lmol of Ni; 10 atm ethylene; 40 °C; 30 min; 100 mL
Activity: 105 gmolꢁ1 (Ni)hꢁ1
.
b
Thus, at a fixed Al/Ni molar ratio of 200 at 80 °C, all the nickel
complexes (Ni1–Ni10) showed good activities and high selectivity
Table 3
Ethylene Oligomerization by Ni3/EASC.a
for a-olefins (Table 5). The activities of the nickel complexes with
R1 = Me decreased in the order, Ni5 > Ni4 > Ni3 > Ni2 > Ni1. Bulky
substituted ligands protected the active species, thereby affording
the highest activity [55]. This explanation also served to explain
the activity trend observed for the nickel complexes with R1 = iPr,
which decreased in the order Ni10 > Ni9 > Ni8 > Ni7 > Ni6. The
activities observed for Ni6–Ni10 (R1 = iPr) were lower than those
of Ni1–Ni5 (R1 = Me), due to the steric and electronic influence of
R1 at the nickel center [55–57].
Entry
Pre-cat.
T (°C)
Al/Ni
t (min)
Act.b
a
-C4 (%)
C4 (%)
1
2
3
4
5
6
7
8
9
10
11
12
13
Ni3
Ni3
Ni3
Ni3
Ni3
Ni3
Ni3
Ni3
Ni3
Ni3
Ni3
Ni3
Ni3
20
60
70
80
90
40
40
40
40
40
80
80
80
200
200
200
200
200
100
150
250
300
400
200
200
200
30
30
30
30
30
30
30
30
30
30
5
0.64
2.29
2.28
4.3
3.58
0.43
0.87
1.06
0.93
0.87
19.1
10.6
6.13
95.4
88.6
84.9
80.3
79.4
83.5
80.8
94.1
94.4
98.2
80.5
74.2
80.3
100
100
100
100
100
100
100
100
100
100
100
100
100
3. Conclusion
A series of N-(2-substituted 5,6,7-trihydroquinolin-8-ylidene)
arylaminonickel(II) dichloride complexes were synthesized and
fully characterized. Upon activation with EASC, all nickel(II) com-
plexes exhibited good activity for ethylene oligomerization with en-
10
20
a
Reaction conditions: 5
lmol of Ni; 10 atm. ethylene; 100 mL toluene.
b
Activity: 105 gmolꢁ1 (Ni)hꢁ1
.
hanced thermal stability at 80 °C and high selectivity for
a-C4.
Catalysts bearing 2-Me substituted ligands generally showed better
activities than did their analogs ligating by 2-iPr substituted ligands.
Less bulky substituents on the aryl group resulted in better catalytic
activities, and additional substituents in the para-position of the aryl
group (from aniline) afforded higher activity.
it was found that the selectivity for
a
-olefins tended to increase with
increasing Al/Ni molar ratio. On fixing the Al/Ni molar ratio at 200,
the influence of temperature was evaluated. On increasing the tem-
perature from 20 to 90 °C, the activity increased until the tempera-
ture reached 90 °C, whereupon the activity decreased slightly. The
highest activity of 4.30 ꢀ 105 gmolꢁ1 (Ni)hꢁ1 was observed at
80 °C. It was also observed that the selectivity for
a-olefins de-
4. Experimental
creased on increasing the temperature.
Catalyst lifetimes were also investigated (entry 11–13, Table 3),
with the activity reaching 1.91 ꢀ 106 gmolꢁ1 (Ni)hꢁ1 at 5 min, but
decreasing rapidly with the time. This is tentatively attributed to
the presence of the electron-rich substituents at R1, which increase
4.1. General considerations
All manipulations of air and/or moisture sensitive compounds
were performed under nitrogen atmosphere using standard Schlenk

24
W. Chai et al. / Inorganica Chimica Acta 385 (2012) 21–26
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 AkzoNobel Corp. Diethylaluminium chloride
(Et2AlCl, 0.79 M in toluene) and ethylaluminium sesquichloride
(EASC, 0.87 M in toluene) were freely obtained from Beijing Yansan
Petrochemical Co. Elemental analysis was conducted on a Flash EA
1112 microanalyzer. IR spectra were recorded on a Perkin–Elmer
System 2000 FT-IR spectrometer using KBr disks in the range
4000–400 cmꢁ1. Gas chromatograph (GC) analysis was performed
with a VARIAN CP-3800 gas chromatograph equipped with a flame
ionization detector and a 30 m column (0.2 mm inert diameter,
4.2.5. 2,6-Diethyl-4-methyl-N-(2-methy-5,6,7-trihydroquinolin-8-
ylidene)phenylaminonickel(II) dichloride (Ni5)
By using a similar procedure as described for Ni1, 2-methyl-
5,6,7-trihydroquinolin-8-one (0.162 g, 1.0 mmol), 2,6-diethyl-4-
methylaniline (0.164 g, 1.0 mmol), NiCl2ꢂ6H2O (0.238 g, 1.0 mmol)
were added into 10 ml glacial acetic acid, and the complex Ni5 was
obtained as a yellow powder, 0.232 g, 53.1% yield. FT-IR (KBr disk,
cmꢁ1): 2960, 2875, 1664, 1630, 1596, 1480, 1455,1272, 1214,
1135, 859, 829, 668. Anal. Calc. for C21H26Cl2N2Ni (436.04): C,
57.84; H, 6.01; N, 6.42. Found: C, 57.51; H, 5.80; N, 6.04%.
4.2.6. 2,6-Dimethyl-N-(2-isopropyl-5,6,7-trihydroquinolin-8-
ylidene)phenylaminonickel(II) dichloride (Ni6)
0.25 lm film thickness).
By using a similar procedure as described for Ni1, 2-isopropyl-
5,6,7-trihydroquinolin-8-one (0.190 g, 1.0 mmol), 2,6-dimethylan-
iline (0.122 g, 1.0 mmol), NiCl2ꢂ6H2O (0.238 g, 1.0 mmol) were
added into 10 ml glacial acetic acid, and the complex Ni6 was
obtained as a yellow powder, 0.249 g, 59.1% yield. FT-IR (KBr disk,
cmꢁ1): 3021, 2952, 2867, 2361, 1628, 1599, 1224, 1205, 1043, 866,
836, 793, , 677. Anal. Calc. for C20H24Cl2N2Ni (422.02): C, 56.92; H,
6.73; N, 6.64. Found: C, 56.46; H, 6.23; N, 6.34%.
4.2. Synthesis of nickel complexes Ni1–Ni10
4.2.1. 2,6-Dimethyl-N-(2-methy-5,6,7-trihydroquinolin-8-
ylidene)phenylaminonickel(II) dichloride (Ni1)
To a 25 ml two-necked round bottom flask, were added 2-
methyl-5,6,7-trihydroquinolin-8-one (1 mmol), 2,6-dimethylani-
line (1.0 mmol), NiCl2ꢂ6H2O (1.0 mmol) and glacial acetic acid
(10 ml). The mixture was stirred at reflux temperature for 5 h,
and then the acid was removed under reduced pressure. The resi-
due was dissolved in 10 ml methanol, and Ni1 was precipitated
when 50 ml of diethyl ether was added. After filtration, the solid
was washed with diethyl ether (3 ꢀ 5 mL), and dried under vac-
uum. The resultant yellow solid weighted 0.275 g (69.8% yield).
FT-IR (KBr disk, cmꢁ1): 2970, 2911, 2855, 2362, 2336, 1622,
1595, 1480, 1274, 1223, 1203, 822, 778, 773, 662. Anal. Calc. for
4.2.7. 2,6-Diethyl-N-(2-isopropyl-5,6,7-trihydroquinolin-8-
ylidene)phenylaminonickel(II) dichloride (Ni7)
By using a similar procedure as described for Ni1, 2-isopropyl-
5,6,7-trihydroquinolin-8-one (0.190 g, 1.0 mmol), 2,6-diethylani-
line (0.150 g, 1.0 mmol), NiCl2ꢂ6H2O (0.238 g, 1.0 mmol) were
added into 10 ml glacial acetic acid, and the complex Ni7 was
obtained as a yellow powder, 0.303 g, 67.4% yield. FT-IR (KBr disk,
cmꢁ1): 2967, 2928, 2881, 2361, 1627, 1595, 1478, 1450, 1280,
1217, 1048, 865, 810, 675. Anal. Calc. for C22H28Cl2N2Ni (450.07):
C, 58.71; H, 6.27; N, 6.22. Found: C, 58.46; H, 6.24; N, 5.86%.
C18H20Cl2N2Ni (393.96): C, 54.88; H, 5.12; N, 7.11. Found: C,
54.56; H, 5.20; N, 6.74%.
4.2.2. 2,6-Diethyl-N-(2-methy-5,6,7-trihydroquinolin-8-
ylidene)phenylaminonickel(II) dichloride (Ni2)
4.2.8. 2,6-Diisopropyl-N-(2-isopropyl-5,6,7-trihydroquinolin-8-
ylidene)phenylaminonickl(II) dichloride (Ni8)
By using a similar procedure as described for Ni1, 2-methyl-
5,6,7-trihydroquinolin-8-one (0.162 g, 1.0 mmol), 2,6-diethylani-
line (0.150 g, 1.0 mmol), NiCl2ꢂ6H2O (0.238 g, 1.0 mmol) were
added into 10 ml glacial acetic acid, and the complex Ni2 was
obtained as a yellow powder, 0.285 g, 67.5% yield. FT-IR (KBr disk,
cmꢁ1): 2964, 2932, 2879, 2362, 2336, 1625, 1598, 1481, 1453,
1274, 1223, 1215, 816, 774, 666. Anal. Calc. for C20H24Cl2N2Ni
(422.02): C, 56.92; H, 5.73; N, 6.64. Found: C, 56.46; H, 6.03; N,
6.34%.
By using a similar procedure as described for Ni1, 2-isopropyl-
5,6,7-trihydroquinolin-8-one (0.190 g, 1.0 mmol), 2,6-isopropylan-
iline (0.178 g, 1.0 mmol), NiCl2ꢂ6H2O (0.238 g, 1.0 mmol) were
added into 10 ml glacial acetic acid, and the complex Ni8 was
obtained as a yellow powder, 0.326 g, 68.2% yield. FT-IR (KBr disk,
cmꢁ1): 2965, 2927, 2870, 2361, 1623, 1598, 1484, 1459, 1217,
1188, 1052, 828, 806, 767. Anal. Calc. for C24H32Cl2N2Ni (478.12):
C, 60.29; H, 6.75; N, 5.86. Found: C, 59.88; H,6.85; N, 5.42%.
4.2.3. 2,6-Diisopropyl-N-(2-methy-5,6,7-trihydroquinolin-8-
ylidene)phenylaminonickel(II) dichloride (Ni3)
4.2.9. 2,4,6-Trimethyl-N-(2-isopropyl-5,6,7-trihydroquinolin-8-
ylidene)phenylaminonickel(II) dichloride (Ni9)
By using a similar procedure as described for Ni1, 2-methyl-
5,6,7-trihydroquinolin-8-one (0.162 g, 1.0 mmol), 2,6-diisopropyl-
aniline (0.178 g, 1.0 mmol), NiCl2ꢂ6H2O (0.238 g, 1.0 mmol) were
added into 10 ml glacial acetic acid, and the complex Ni3 was
obtained as a yellow powder, 0.361 g, 80.2% yield. FT-IR (KBr disk,
cmꢁ1): 2963, 2928, 2866, 2362, 2335, 1622, 1594, 1479, 1449,
1277, 809, 773, 667. Anal. Calc. for C22H28Cl2N2Ni (450.07): C,
58.71; H, 6.27; N, 6.22. Found: C, 58.51; H, 6.00; N, 5.77%.
By using a similar procedure as described for Ni1, 2-isopropyl-
5,6,7-trihydroquinolin-8-one (0.190 g, 1.0 mmol), 2,4,6-trimethyl-
aniline (0.136 g, 1.0 mmol), NiCl2ꢂ6H2O (0.238 g, 1.0 mmol) were
added into 10 ml glacial acetic acid, and the complex Ni9 was ob-
tained as a yellow powder 0.281 g, 64.2% yield. FT-IR (KBr disk,
cmꢁ1): 2959, 2916, 2871, 1622, 1596, 1470, 1452, 1225, 1140,
1041, 852, 672. Anal. Calc. for C21H26Cl2N2Ni (436.04): C, 57.84;
H, 6.01; N, 6.42. Found: C, 57.58; H, 6.04; N, 6.17%.
4.2.4. 2,4,6-Trimethyl-N-(2-methy-5,6,7-trihydroquinolin-8-
ylidene)phenylaminonickel(II) dichloride (Ni4)
4.2.10. 2,6-Diethyl-4-methyl-N-(2-isopropyl-5,6,7-trihydroquinolin-
8-ylidene)phenylaminonickel(II) dichloride (Ni10)
By using a similar procedure as described for Ni1, 2-methyl-
5,6,7-trihydroquinolin-8-one (0.162 g, 1.0 mmol), 2,4,6-trimethyl-
aniline (0.136 g, 1.0 mmol), NiCl2ꢂ6H2O (0.238 g, 1.0 mmol) were
added into 10 ml glacial acetic acid, and the complex Ni4 was
obtained as a yellow powder, 0.281 g, 68.8% yield. FT-IR (KBr disk,
cmꢁ1): 3118, 2948, 1749, 1724, 1633, 1600, 1485, 1380, 1223, 856,
828, 795, 666. Anal. Calc. for C19H22Cl2N2Ni (407.99): C, 55.93; H,
5.44; N, 6.87. Found: C, 55.51; H, 5.49; N, 5.84%.
By using a similar procedure as described for Ni1, 2-isopropyl-
5,6,7-trihydroquinolin-8-one (0.190 g, 1.0 mmol), 2,6-diethyl-4-
methylaniline (0.164 g, 1.0 mmol), NiCl2ꢂ6H2O (0.238 g, 1.0 mmol)
were added into 10 ml glacial acetic acid, and the complex Ni10
was obtained as a yellow powder, 0.334 g, 72.0% yield. FT-IR (KBr
disk, cmꢁ1): 2966, 2931, 2874, 1621, 1589, 1480, 1460, 1214,
1140, 1046, 864, 832, 654. Anal. Calc. for C23H30Cl2N2Ni (464.10):
C, 59.52; H, 6.52; N, 6.04. Found: C, 59.44; H, 6.71; N, 5.89%.

W. Chai et al. / Inorganica Chimica Acta 385 (2012) 21–26
25
Table 6
Crystal data and structure refinement for Ni1, Ni4 and Ni10.
Ni1ꢂCH3OH
19H24Cl2N2NiO
Ni4ꢂCH3OH
20H25Cl2N2NiO
Ni10
Empirical formula
C
C
C
46H60Cl4N4Ni2
Formula weight
T (K)
Wavelength (Å)
Crystal system, space group
a (Å)
b (Å)
c (Å)
426.01
173(2)
0.71073
triclinic, P1
9.5570(19)
10.730(2)
10.858(2)
65.41(3)
439.01
293(2)
0.71073
triclinic, P1
9.3985(19)
11.088(2)
11.367(2)
63.92(3)
928.20
173(2)
0.71073
triclinic, P1
13.605(3)
14.196(3)
15.482(3)
67.48(3)
ꢀ
ꢀ
ꢀ
a
(°)
b (°)
78.80(3)
77.70(3)
80.63(3)
c
(°)
70.50(3)
952.4(3)
2
1.485
1.308
70.02(3)
997.1(3)
2
1.462
1.252
73.42(3)
2642.3(9)
2
1.167
0.946
V (Å3)
Z
Dcalc (gcmꢁ3
)
l
(mmꢁ1
)
F(000)
444
458
976
Crystal size (mm)
h Range (°)
Limiting indices
0.55 ꢀ 0.47 ꢀ 0.19
2.07–27.51
ꢁ12 6 h 6 12
ꢁ13 6 k 6 13
ꢁ14 6 l 6 14
8477
0.42 ꢀ 0.37 ꢀ 0.21
2.00–30.04
ꢁ13 6 h 6 13
ꢁ15 6 k 6 15
ꢁ15 6 l 6 16
15528
0.56 ꢀ 0.45 ꢀ 0.29
1.56–27.49
ꢁ17 6 h 6 15
ꢁ17 6 k 6 18
ꢁ20 6 l 6 20
23573
No. of reflections collected
No. unique rflns (Rint
Number of parameters
)
4315(0.0376)
231
5795(0.0384)
240
12007(0.0438)
505
Completeness to h (%)
98.7
1.089
99.3
1.036
99.0
1.060
Goodness of fit on F2
P
Final R indices [I > 2 (I)]
R1 = 0.0497
wR2 = 0.1407
R1 = 0.0555
wR2 = 0.1506
0.729 and -0.690
R1 = 0.0517
wR2 = 0.1531
R1 = 0.0547
wR2 = 0.1589
1.948 and ꢁ0.725
R1 = 0.0597
wR2 = 0.1662
R1 = 0.0707
wR2 = 0.1746
0.567 and ꢁ0.840
R indices (all data)
Largest diff peak and hole (eÅꢁ3
)
4.3. X-ray crystallographic studies
Acknowledgments
Single crystals of Ni1ꢂCH3OH, Ni4ꢂCH3OH and Ni10 suitable for
This work is supported by MOST 863Program No. 2009AA033601.
The EPSRC are thanked for the award of a travel grant (to C.R.).
X-ray diffraction analysis were obtained by laying diethyl ether
on methanol solutions at room temperature. With graphite-mono-
0
chromatic Mo Ka radiation (k = 0.71073 ÅA) at 173(2) K, cell param-
Appendix A. Supplementary material
eters 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. [58] Details of the X-ray structure determina-
tions and refinements are provided in Table 6.
CCDC 846647, 846648 and 846649 contain the supplementary
crystallographic data for complexes Ni1, Ni4 and Ni10, respectively.
These data can be obtained free of charge from The Cambridge Crys-
tallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
Supplementary data associated with this article can be found, in
the online version, at doi:10.1016/j.ica.2011.12.008.
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