Synthesis and crystal structures of two dinuclear nickel(II) complexes derived from 2-ethoxy-6-[(2-phenylaminoethylimino)methyl]phenol

Article abstract of DOI:10.1080/15533174.2010.509297

Two nickel(II) complexes, [Ni2L[image omitted]-NCS)] (1) and 2[Ni2L[image omitted]-N3)][image omitted]H₂O (2), derived from the Schiff base 2-ethoxy-6-[(2-phenylaminoethylimino)methyl]phenol (HL) have been prepared and characterized by elementa

Full text of DOI:10.1080/15533174.2010.509297

Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry, 40:601–605, 2010
Copyright © Taylor & Francis Group, LLC
ISSN: 1553-3174 print / 1553-3182 online
DOI: 10.1080/15533174.2010.509297
Synthesis and Crystal Structures of Two
Dinuclear Nickel(II) Complexes Derived from
2-Ethoxy-6-[(2-phenylaminoethylimino)methyl]phenol
Zhe Hong
School of Chemical Engineering and Material Science, Eastern Liaoning University, Dandong,
P. R. China
EXPERIMENTAL
Two nickel(II) complexes, [Ni2L3(µ1,1-NCS)] (1) and
Materials and Measurements
2[Ni2L3(µ1,1-N3)]·H2O (2), derived from the Schiff base
3-Ethoxysalicylaldehyde and N-phenylethane-1,2-diamine
2-ethoxy-6-[(2-phenylaminoethylimino)methyl]phenol (HL) have
been prepared and characterized by elemental analysis, IR
spectra, and single crystal X-ray diffraction. Complex (1) is an
end-on thiocyanato- and phenolate O-bridged dinuclear com-
pound. Complex (2) consists of two end-on azido- and phenolate
O-bridged dinuclear complex molecules and one water molecule of
crystallization. The Ni atoms in the complexes are six-coordinated
in octahedral geometries.
of AR grade were purchased from Aldrich. CHN elemental
analyses were performed with a Perkin-Elmer 240C elemental
analyzer. I.r. spectra (KBr disks) were recorded on a Perkin-
Elmer 257 spectrophotometer.
Synthesis of HL
The Schiff base HL was prepared by the condensation re-
action of equimolar quantities of 3-ethoxysalicylaldehyde with
N-phenylethane-1,2-diamine in methanol at room temperature.
Yield: 93%. Anal. calcd (%) for C17H20N2O2: C, 71.8; H, 7.1;
N, 9.8. Found (%): C, 71.5; H, 7.2; N, 10.0.
Keywords crystal structure, nickel, Schiff base, synthesis
INTRODUCTION
Schiff bases synthesized from the condensation reaction
of salicylaldehydes and its derivatives with primary amines
are an important class of versatile ligands.[1–4] Transition
metal complexes derived from Schiff bases, especially for
the polynuclear complexes, have received much attention due
to their wide application.[5–7] The azide and thiocyanate lig-
ands are interesting bridging groups in the construction of
polynuclear complexes.[8–11] To the best of our knowledge, the
metal complexes derived from the Schiff base 2-ethoxy-6-[(2-
phenylaminoethylimino)methyl]phenol (HL) have never been
reported. In the present paper, two new dinuclear nickel(II)
complexes with the Schiff base HL have been prepared and
characterized.
Synthesis of [Ni2L3(␮1,1-NCS)] (1)
A methanol solution (5 mL) of Ni(CH3COO)2·4H2O
(124.3 mg, 0.5 mmol) was added to a methanol solution (10
mL) of HL (142.2 mg, 0.5 mmol) and ammonium thiocyanate
(38.0 mg, 0.5 mmol), and the mixture was stirred and heated
under reflux (30 min). The solution was then cooled to room
temperature and filtered. Green, X-ray quality crystals of the
complex were obtained after five days by allowing the filtra-
tion to evaporate in air. Yield: 123 mg (72%) on the basis of
HL. Anal. calcd. for C52H57N7Ni2O6S: C, 60.9; H, 5.6; N, 9.6.
Found: C, 60.2; H, 5.8; N, 9.9%.
Synthesis of 2[Ni2L3(␮1,1-N3)]·H2O (2)
A methanol solution (5 mL) of Ni(CH3COO)2·4H2O (124.3
mg, 0.5 mmol) was added to a methanol solution (10 mL) of HL
(142.2 mg, 0.5 mmol) and sodium azide (33.0 mg, 0.5 mmol),
and the mixture was stirred and heated under reflux (30 min).
The solution was then cooled to room temperature and filtered.
Green, X-ray quality crystals of the complex were obtained after
a week by allowing the filtration to evaporate in air. Yield: 97 mg
(60%) on the basis of HL. Anal. calcd. for C192H208N36Ni8O25:
C, 59.3; H, 5.4; N, 13.0. Found: C, 59.8; H, 5.7; N, 12.5%.
Received 6 February 2010; accepted 18 May 2010.
The author acknowledges Eastern Liaodong University for funding
this study.
Address correspondence to Zhe Hong, School of Chemical Engi-
neering and Material Science, Eastern Liaoning University, Dandong
118003, P. R. China. E-mail: hongzhe57@126.com
601

602
Z. HONG
TABLE 1
Crystallographic and experimental data for the complexes
TABLE 2
◦
˚
Selected bond lengths (A) and bond angles ( ) for the
complexes
Complex
(1)
(2)
(1)
Ni1-O1
Ni1-O5
Ni1-N2
Ni2-O5
Ni2-O3
Ni2-N4
O1-Ni1-N1
N1-Ni1-O5
N1-Ni1-N7
O1-Ni1-N2
O5-Ni1-N2
O1-Ni1-O6
O5-Ni1-O6
N2-Ni1-O6
O5-Ni2-O3
O5-Ni2-N5
O3-Ni2-N5
N3-Ni2-N4
N5-Ni2-N4
N3-Ni2-N7
N5-Ni2-N7
Formula
FW
Crystal
C52H57N7Ni2O6S
1025.5
Block/green
C192H208N36Ni8O25
3889.6
Block/green
1.965(3)
1.980(3)
Ni1-N1
Ni1-N7
1.969(4)
2.116(4)
2.188(4)
Ni1-O6
2.324(3)
shape/colour
1.985(3)
Ni2-N3
1.993(5)
Crystal size/mm
Crystal system
Space group
0.20 × 0.20 × 0.18 0.23 × 0.20 × 0.20
2.002(3)
Ni2-N5
2.067(5)
monoclinic
C2/c
triclinic
P-1
2.186(5)
Ni2-N7
2.272(4)
93.50(17)
171.59(15)
92.28(16)
176.29(15)
89.51(13)
86.21(12)
73.37(12)
95.36(14)
93.06(13)
88.65(17)
92.34(16)
82.1(2)
O1-Ni1-O5
O1-Ni1-N7
O5-Ni1-N7
N1-Ni1-N2
N7-Ni1-N2
N1-Ni1-O6
N7-Ni1-O6
O5-Ni2-N3
N3-Ni2-O3
N3-Ni2-N5
O5-Ni2-N4
O3-Ni2-N4
O5-Ni2-N7
O3-Ni2-N7
N4-Ni2-N7
94.16(14)
91.00(14)
84.14(15)
82.81(16)
88.86(15)
110.62(13)
157.05(14)
165.80(18)
92.96(19)
103.9(2)
89.87(15)
169.87(18)
80.06(14)
86.58(14)
84.38(17)
˚
a/A
25.1941(9)
13.5637(4)
30.5575(8)
90
95.529(3)
90
10393.7(6)
8
0.71073
298(2)
12.602(3)
18.571(4)
21.656(4)
107.98(3)
90.50(3)
96.94(3)
4779.7(16)
1
˚
b/A
˚
c/A
α/◦
β/◦
γ /◦
3
˚
V /A
Z
˚
λ (MoKα) /A
T /K
0.71073
298(2)
0.846
µ /mm−1
(Mo-Kα)
Tmin
0.819
97.43(19)
87.47(18)
168.57(18)
0.8534
0.8666
0.8293
0.8491
Tmax
Reflections/
parameters
Independent
reflections
F(000)
10347/625
20053/1207
(2)
Ni1-N1
Ni1-O5
Ni1-N2
Ni2-O5
Ni2-N3
Ni2-N7
Ni3-N10
Ni3-O11
Ni3-N11
Ni4-N12
Ni4-O9
Ni4-N13
N1-Ni1-O1
O1-Ni1-O5
O1-Ni1-N7
N1-Ni1-N2
O5-Ni1-N2
N1-Ni1-O6
O5-Ni1-O6
N2-Ni1-O6
O5-Ni2-N3
O5-Ni2-N5
N3-Ni2-N5
O3-Ni2-N7
N5-Ni2-N7
O3-Ni2-N4
1.96(4)
1.98(3)
2.20(4)
1.98(3)
1.99(4)
2.23(4)
1.97(4)
1.98(3)
2.19(5)
Ni1-O1
Ni1-N7
Ni1-O6
Ni2-O3
Ni2-N5
Ni2-N4
Ni3-O7
Ni3-N16
Ni3-O12
Ni4-O11
Ni4-N14
Ni4-N16
N1-Ni1-O5
N1-Ni1-N7
O5-Ni1-N7
O1-Ni1-N2
N7-Ni1-N2
O1-Ni1-O6
N7-Ni1-O6
O5-Ni2-O3
O3-Ni2-N3
O3-Ni2-N5
O5-Ni2-N7
N3-Ni2-N7
O5-Ni2-N4
N3-Ni2-N4
1.98(3)
2.07(4)
2.23(3)
1.99(3)
2.07(4)
2.24(4)
1.98(4)
2.07(4)
2.24(3)
4523
10501
4304
0.973
2036
0.986
Goodness of fit
on F2
R1, wR2
[I ≥ 2σ(I)]a
R1, wR2
(all data)a
ꢀ
0.0540, 0.1295
0.1455, 0.1678
ꢀ
0.0586, 0.1246
0.1316, 0.1580
1.99(4)
2.01(3)
2.19(4)
1.99(3)
2.08(4)
2.22(4)
ꢀ
aR1 = ||Fo| – |Fc||/ |Fo|, wR2 = [ w(Fo2 – Fc2)2/
ꢀ
w(Fo2)2]1/2
.
93.1(15)
92.4(13)
93.2(15)
83.4(16)
91.1(14)
104.3(14)
75.1(12)
93.5(14)
164.5(14)
88.2(14)
106.0(15)
87.9(14)
165.7(15)
171.2(14)
174.5(15)
99.1(16)
81.4(14)
176.3(14)
86.2(15)
88.5(13)
156.4(14)
93.7(13)
92.2(15)
91.4(14)
77.6(13)
88.2(15)
89.9(13)
82.5(15)
Crystal Structure Determination
The single crystals of the two complexes were chosen and
glued to thin glass fibers by epoxy glue in air for data collection.
The diffraction data were collected on a Bruker SMART 1000
˚
CCD with Mo Kα radiation (λ = 0.71073 A) at 298(2) K us-
ing the ω scan method. A multi-scan absorption correction was
applied. The structures were solved by direct methods and differ-
ence Fourier synthesis. Crystal data collection, parameters, and
refinement statistics for the two complexes are listed in Table 1.
All of the non-H atoms were refined anisotropically. Amino
and water H atoms of the two complexes were located from
difference Fourier maps and refined isotropically, with N−H
˚
distances restrained to 0.90(1) A. Other H atoms were included
(Continued on next page)

TWO DINUCLEAR NICKEL(II) COMPLEXES
603
TABLE 2
and high purity. The Schiff base HL is yellow oil, which can be
diluted by methanol, ethanol, acetonitrile, acetone, and dichloro-
form. Both complexes are very stable in air at room temperature.
The obvious difference between the structures is the bridging
groups, thiocyanate for (1) and azide for (2).
◦
˚
Selected bond lengths (A) and bond angles ( ) for the
complexes (Continued)
N5-Ni2-N4
96.8(14)
92.8(18)
94.3(14)
94.3(16)
83.5(18)
89.4(15)
105.5(16)
75.5(13)
93.8(15)
90.6(16)
105.9(18)
93.2(16)
90.2(15)
96.7(17)
76.4(14)
164.4(16)
N7-Ni2-N4
84.9(14)
172.9(17)
98.7(17)
80.3(15)
176.1(16)
87.3(16)
86.2(14)
155.8(16)
165.1(16)
94.1(13)
88.0(15)
82.9(17)
169.4(15)
89.7(17)
88.4(16)
83.2(17)
N10-Ni3-O7
O7-Ni3-O11
O7-Ni3-N16
N10-Ni3-N11
O11-Ni3-N11
N10-Ni3-O12
O11-Ni3-O12
N11-Ni3-O12
N12-Ni4-O9
N12-Ni4-N14
O9-Ni4-N14
O11-Ni4-N13
N14-Ni4-N13
O11-Ni4-N16
N14-Ni4-N16
N10-Ni3-O11
N10-Ni3-N16
O11-Ni3-N16
O7-Ni3-N11
N16-Ni3-N11
O7-Ni3-O12
N16-Ni3-O12
N12-Ni4-O11
O11-Ni4-O9
O11-Ni4-N14
N12-Ni4-N13
O9-Ni4-N13
N12-Ni4-N16
O9-Ni4-N16
N13-Ni4-N16
I.R. Spectra
The I.R. spectra of HL shows the characteristic ν(O-H) and
ν(N-H) absorption bands at 3415 and 3223 cm–1, respectively.
The ν(O-H) bands of HL were absent after complexation. The
absorption attributed to the ν(C=N) vibrations are at 1627
cm–1for HL; however, the corresponding vibrations in the two
complexes are lower shifted about 12 cm–1, as that described in
similar Schiff base complexes.[13,14] The strong absorption band
observed for HL at 1285 cm–1can be attributed to the phenolic
stretch. The bands are observed at higher wave numbers at 1303
cm–1 in both complexes, suggesting involvement of the oxygen
atom of the Ar–O group in coordination. In (1), the very strong
absorption band at 2073 cm–1can be assigned to the vibration
of the thiocyanate group, and that in (2) at 2035 cm–1can be as-
signed to the vibration of the azide group. The close resemblance
of the shape and the positions of the absorption bands in the I.R.
spectra suggest similar coordination mode of the ligands.
in calculated positions, and assigned isotropic thermal parame-
ters, which were set to ride on the parent atoms. All calculations
were performed using the SHELXTL-97 package.[12]
Structure Description of the Complexes
RESULTS AND DISCUSSION
Selected bond lengths and angles are listed in Table 2. The
The condensation reactions of aldehydes with primary molecular structures of the complexes (1) and (2) are shown in
amines readily produce Schiff bases, with quantitative yields Figures 1, 2a and 2b, respectively. The two complexes are very
FIG. 1. Molecular structure of the complex (1) at the 30% ellipsoid. H atoms have been omitted for clarity.

604
Z. HONG
FIG. 2. (a) Molecular structure for the Ni1 and Ni2 complex molecule of (2) at the 30% ellipsoid. H atoms have been omitted for clarity. (b) Molecular structure
for the Ni3 and Ni4 complex molecule of (2) at the 30% ellipsoid. H atoms have been omitted for clarity.

TWO DINUCLEAR NICKEL(II) COMPLEXES
605
similar to each other. Complex (1) is an end-on thiocyanato- and
phenolate O-bridged dinuclear compound. Complex (2) con-
sists of two end-on azido- and phenolate O-bridged dinuclear
complex molecules and one water molecule of crystallization.
There are three Schiff base ligands in each dinuclear complex
molecule, one of which acts as a bridging ligand.
2. Borisova, N.E., Reshetova, M.D., and Ustynyuk, Y.A. Metal-free methods
in the synthesis of macrocyclic Schiff bases. Chem. Rev., 2007, 107, 46–79.
3. Lalehzari, A., Desper, J., and Levy, C.J. Double-stranded monohelical com-
plexes from an unsymmetrical chiral Schiff-base ligand. Inorg. Chem.,
2008, 47, 1120–1126.
4. Tanaka, T., Yasuda, Y., and Hayashi, M. New chiral Schiff base as a triden-
tate ligand for catalytic enantioselective addition of diethylzinc to aldehy-
des. J. Org. Chem., 2006, 71, 7091–7093.
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dinuclear, and polynuclear dioxomolybdenum(VI)-tridentate Schiff base
complexes: crystal structures and properties. Inorg. Chim. Acta, 1998, 282,
209–216.
7. Benetollo, F., Di Bernardo, P., Tamburini, S., Vigato, P.A., and Zanonato,
P. Mononuclear and polynuclear complexes with a side-off compartmental
Schiff base. Inorg. Chem. Commun., 2008, 11, 246–251.
8. Ray, A., Banerjee, S., Butcher, R.J., Desplanches, C., and Mitra, S. Two
new end-on azido bridged dinuclear copper(II) and cobalt(III) complexes
derived from the (E)-Nꢀ-((pyridin-2-yl)methylene) acetohydrazide Schiff
base ligand: Characterisation, crystal structures and magnetic study. Poly-
hedron, 2008, 27, 2409–2415.
9. Yue, Y.-F., Gao, E.-Q., Fang, C.-J., Zheng, T., Liang, J., and Yan, C.-H. Three
azido-bridged Mn(II) complexes based on open-chain diazine Schiff-base
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2008, 8, 3295–3301.
10. Carranza, J., Sletten, J., Lloret, F., and Julve, M. Preparation, crystal struc-
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plexes with 2,2ꢀ-biimidazole or 2-(2ꢀ-pyridyl)imidazole as terminal ligands.
Polyhedron, 2009, 28, 2249–2257.
The Ni atoms in the complexes are six-coordinated in octa-
hedral geometries. The Ni1 atom in (1), Ni1, and Ni3 atoms in
(2) are coordinated by one phenolate O, one imine N, and one
amine N atoms of one Schiff base ligand, by one phenolate O
and one ether O atoms of another Schiff base ligand, and by
one N atom of a bridging ligand, viz. thiocyanate for (1) and
azide for (2). The Ni2 atom in (1), Ni2 and Ni4 atoms in (2) are
coordinated by one phenolate O, one imine N and one amine
N atoms of one Schiff base ligand, by one phenolate O and
one imine N atoms of another Schiff base ligand, and by one N
atom of a bridging ligand, viz. thiocyanate for (1) and azide for
. . .
˚
(2). The Ni Ni distances are 3.137(2) A for (1), 3.166(3) and
˚
3.195(3) A for (2), respectively.
In both complexes, the bond lengths and angles are compa-
rable to each other, and are also comparable to those in other
Schiff base copper(II) complexes.[15–17]The distortion of each
octahedral coordination can be observed from the trans coordi-
nate bond angles, which are caused by the strain created by the
four- and five-membered chelate rings.
11. Hong, Z. Synthesis, crystal structures, and antimicrobial activity of two
thiocyanato-bridged dinuclear copper(II) complexes derived from 2,4-
dibromo-6-[(2-diethylaminoethylimino)methyl]phenol and 4-nitro-2-[(2-
ethylaminoethylimino)methyl]phenol. Trans. Met. Chem., 2008, 33, 797–
802.
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characterization and physicochemical properties of copper(II) complexes
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CONCLUSION
In the present work, two new structurally similar
nickel(II) complexes with the Schiff base 2-ethoxy-6-
[(2-phenylaminoethylimino)methyl]phenol and thiocyanate or
azide groups have been prepared and structural characterized.
The Schiff base coordinates to the nickel atoms through the phe-
nolate O, imine N, amine N, and ether O atoms. The thiocyanate
and azide groups play the same role in the coordination, both
adopt end-on bridging mode.
14. Kannappan, R., Tanase, S., Mutikainen, I., Turpeinen, U., and Reedijk, J.
Square-planar copper(II) halide complexes of tridentate ligands with π ···π
stacking interactions and alternating short and long Cu· · ·Cu distances.
Inorg. Chim. Acta, 2005, 358, 383–388.
15. Kurtaran, R., Emregul, K.C., Arici, C., Ercan, F., Catalano, V.J., and Atakol,
O. Synthesis and crystal structure of linear chain homotetranuclear com-
plexes with N−3 . Synth. React. Inorg. Met.-Org. Chem., 2003, 33, 281–296.
16. Mallah, T., Boillot, M.L., Kahn, O., Gouteron, J., Jeannin, S., and Jeannin,
Y. Crystal structures and magnetic properties of µ-phenolato copper(II) bin-
uclear complexes with hydroxo, azido, and cyanato-O exogenous bridges.
Inorg. Chem., 1986, 25, 3058–3065.
17. Song, Y., Massera, C., Roubeau, O., Gamez, P., Lanfredi, A.M.M., and
Reedijk, J. An unusual open cubane structure in a µ1,1-azido- and alkoxo-
bridged tetranuclear copper(II) complex, [Cu4L2(µ1,1-N3)2]·5H2O (H3L =
N, Nꢀ-(2-hydroxylpropane-1,3-diyl)bis-salicylideneimine). Inorg. Chem.,
2004, 43, 6842–6847.
SUPPLEMENTARY MATERIAL
CCDC 764940 and 764941 contain the supplementary crys-
tallographic data for the two complexes. These data can
be obtained free of charge via http://www.ccdc.ac.uk/conts/
retrieving.html, or from the Cambridge Crystallographic Data
Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax:
(+44)1223-336-033; or email: deposit@ccdc.cam.ac.uk.
REFERENCES
1. Sprung, M.A. A summary of the reactions of aldehydes with amines. Chem.
Rev., 1940, 26, 297–338.

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