Synthesis, characterization, and crystal structures of copper(II) and zinc(II) complexes derived from the tridentate Schiff bases 2-[1-(pyridin-2- ylmethylimino) ethyl]phenol and (1-pyridin-2-ylethylidene)pyridin-2- ylmethylamine

Article abstract of DOI:10.1080/15533174.2011.618483

A centrosymmetric phenolate oxygen bridged dinuclear copper(II) complex [Cu₂(L¹)₂(N₃)₂] (1) and a mononuclear zinc(II) complex [Zn(L²)(NCS)₂] (2), where HL¹ = 2-[1-(py

Full text of DOI:10.1080/15533174.2011.618483

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Synthesis, Characterization, and Crystal Structures of
Copper(II) and Zinc(II) Complexes Derived From the
Tridentate Schiff Bases 2-[1-(pyridin-2-ylmethylimino)
ethyl]phenol and (1-pyridin-2-ylethylidene)pyridin-2-
ylmethylamine
Da-Hua Shi a b , Zhi-Ling Cao a , Wei-Wei Liu a , Rui-Bo Xu a , Liu-Liu Gao a & Qian Zhang a
a School of Chemical Engineering , Huaihai Institute of Technology , Lianyungang , P. R.
China
b Jiangsu Key Laboratory of Marine Biotechnology , Huaihai Institute of Technology ,
Lianyungang , P. R. China
Accepted author version posted online: 18 Apr 2012.Published online: 11 Jul 2012.
To cite this article: Da-Hua Shi , Zhi-Ling Cao , Wei-Wei Liu , Rui-Bo Xu , Liu-Liu Gao & Qian Zhang (2012) Synthesis,
Characterization, and Crystal Structures of Copper(II) and Zinc(II) Complexes Derived From the Tridentate Schiff Bases 2-[1-
(pyridin-2-ylmethylimino) ethyl]phenol and (1-pyridin-2-ylethylidene)pyridin-2- ylmethylamine, Synthesis and Reactivity in
Inorganic, Metal-Organic, and Nano-Metal Chemistry, 42:6, 864-867
To link to this article: http://dx.doi.org/10.1080/15533174.2011.618483
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Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry, 42:864–867, 2012
Copyright ꢀ Taylor & Francis Group, LLC
C
ISSN: 1553-3174 print / 1553-3182 online
DOI: 10.1080/15533174.2011.618483
Synthesis, Characterization, and Crystal Structures of
Copper(II) and Zinc(II) Complexes Derived From the
Tridentate Schiff Bases 2-[1-(pyridin-2-ylmethylimino)
ethyl]phenol and (1-pyridin-2-ylethylidene)pyridin-2-
ylmethylamine
Da-Hua Shi,1,2 Zhi-Ling Cao,1 Wei-Wei Liu,1 Rui-Bo Xu,1 Liu-Liu Gao,1
and Qian Zhang1
1School of Chemical Engineering, Huaihai Institute of Technology, Lianyungang, P. R. China
2Jiangsu Key Laboratory of Marine Biotechnology, Huaihai Institute of Technology, Lianyungang,
P. R. China
article, a centrosymmetric phenolate oxygen bridged dinu-
clear copper(II) complex [Cu2(L1)2(N3)2] (1) and a mononu-
clear zinc(II) complex [Zn(L2)(NCS)2] (2), where HL1 = 2-
[1-(pyridin-2-ylmethylimino)ethyl]phenol and L2 = (1-pyridin-
2-ylethylidene)pyridin-2-ylmethylamine, were synthesized and
structurally characterized.
A
centrosymmetric phenolate oxygen bridged dinuclear
copper(II) complex [Cu2(L1)2(N3)2] (1) and a mononuclear
zinc(II) complex [Zn(L2)(NCS)2] (2), where HL1
2-[1-
(pyridin-2-ylmethylimino)ethyl]phenol and L2
(1-pyridin-
=
=
2-ylethylidene)pyridin-2-ylmethylamine, were synthesized and
structurally characterized by physicochemical methods and single-
crystal X-ray diffraction. The Cu atom in (1) is five-coordinated in
a slightly distorted square pyramidal geometry, and the Zn atom
in (2) is five-coordinated in a severely distorted square pyramidal
geometry.
Keywords copper, crystal structure, Schiff base, synthesis, zinc
EXPERIMENTAL
INTRODUCTION
Materials and Methods
Schiff bases and their complexes have been received con-
siderable attention for their easy syntheses, versatile structures,
and interesting properties including biological activities, mag-
netism, and catalysis.[1–6] Recently, we have reported the syn-
thesis, structures, and urease inhibitory activities of some Schiff
base complexes.[7–9] As an extension of the work on the prepa-
ration and structures of Schiff base complexes, in the present
2-Acetylphenol,
2-acetylpyridine,
and
2-
aminomethylpyridine of AR grade were purchased from
Lancaster. Copper acetate, zinc acetate, sodium azide, am-
monium thiocyanate, and solvents were purchased from
Beijing Chemical Reagent Company and were used as received.
Elemental analyses for C, H, and N were performed on a Perkin-
Elmer 240C elemental analyzer (Shanghai, China). Elemental
analyses for Cu and Zn were determined by titration. The IR
spectra were recorded on a Nicolet AVATAR 360 spectrometer
(USA) as KBr pellets in the 4000–400 cm−1 region.
Received 15 August 2011; accepted 21 August 2011.
Synthesis of HL1
This work was financially supported by the Natural Science Founda-
tion of Jiangsu Province (BK2009640), the Open-end Funds of Jiangsu
Key Laboratory of Marine Biotechnology, Huaihai Institute of Technol-
ogy (2010HS04), the Natural Science Foundation of Huaihai Institute
To
a
methanol
solution
(20
mL)
of
2-acetylphenol (1.0 mmol, 136 mg) was added a methanol
of Technology (KQ09029), the Major Program for the Natural Science solution (20 mL) of 2-aminomethylpyridine (1.0 mmol,
Research of the Jiangsu Higher Education Institutions of China (Grant
108 mg), with continuous stirring. The mixture was stirred for
No. 10KJA170003), and the Six Kinds of Professional Elite Foundation
30 min at room temperature to give a yellow solution. Then
of Jiangsu Province (No. 07-A-024).
the methanol was evaporated to give yellow gummy product
Address correspondence to Da-Hua Shi, School of Chemical Engi-
of HL1. Anal. Calcd. C14H14N2O: C, 74.3; H, 6.2; N, 12.4%.
neering, Huaihai Institute of Technology, Lianyungang 222005, P. R.
China. E-mail: dahua shi@126.com
Found: C, 74.1; H, 6.3; N, 12.6%.
864

COPPER(II) AND ZINC(II) COMPLEXES
865
Synthesis of L2
Synthesis of [Zn(L2)(NCS)2] (2)
The Schiff base L2 (0.1 mmol, 21.1 mg), ammonium thio-
To a methanol solution (20 mL) of 2-acetylpyridine
(1.0 mmol, 121 mg) was added a methanol solution (20 mL) cyanate (0.2 mmol, 15.2 mg), and zinc acetate (0.1 mmol,
of 2-aminomethylpyridine (1.0 mmol, 108 mg) with continuous 22.0 mg) were mixed and stirred in methanol (15 mL) for 30 min
stirring. The mixture was stirred for 30 min at room temperature at room temperature. The mixture was filtered and the colorless
to give a yellow solution. Then the methanol was evaporated to block-shaped single crystals of (2), suitable for X-ray diffrac-
give yellow oil of L2. Anal. Calcd. C13H13N3: C, 73.9; H, 6.2; tion, were formed on slow evaporation of the filtrate in air. Yield:
N, 19.9%. Found: C, 73.6; H, 6.2; N, 20.1%.
45%. Anal. Calcd. C15H13N5S2Zn: C, 45.9; H, 3.3; N, 17.8; Zn,
16.6%. Found: C, 46.1; H, 3.3; N, 18.0; Zn, 16.9%.
Synthesis of [Cu2(L1)2(N3)2] (1)
X-Ray Crystallography
The Schiff base HL1 (0.1 mmol, 22.6 mg), sodium azide
(0.2 mmol, 13.0 mg), and copper acetate (0.1 mmol, 20.0 mg)
were mixed and stirred in methanol (15 mL) for 30 min at room
temperature. The mixture was filtered and the blue block-shaped
single crystals of (1), suitable for X-ray diffraction, were formed
on slow evaporation of the filtrate in air. Yield: 38%. Anal. Calcd.
C28H26Cu2N10O2: C, 50.8; H, 4.0; N, 21.2; Cu, 19.2%. Found:
C, 50.4; H, 4.1; N, 21.0; Cu, 19.7%.
Diffraction intensities for the complexes were collected at
298(2) K using a Bruker SMART 1000 CCD area-detector
(Germany) with MoKα radiation (λ = 0.71073 Å). The col-
lected data were reduced with the SAINT program (Bruker,
Madison, WI, USA),[10] and multiscan absorption corrections
were performed using the SADABS program (Sheidrick, G.M.,
Germany).[11] Both structures were solved by direct meth-
ods. The complexes were refined against F2 by full-matrix
TABLE 1
Crystallographic data for the complexes
(1)
(2)
Formula
FW
C28H26Cu2N10O2
661.7
C15H13N5S2Zn
392.8
Crystal shape/color
Crystal size (mm)
T (K)
block/blue
0.37 × 0.35 × 0.32
298(2)
block/colorless
0.17 × 0.15 × 0.15
298(2)
λ (MoKα) (Å)
Crystal system
Space group
a (Å)
0.71073
monoclinic
P21/n
10.076(3)
8.039(2)
16.656(4)
96.210(3)
1341.2(6)
2
0.71073
monoclinic
C2/c
14.247(3)
8.658(2)
15.357(3)
110.947(2)
1769.1(7)
4
b (Å)
c (Å)
β (◦)
V (Å3)
Z
µ (MoKα) (cm−1
)
1.634
1.629
Tmin
Tmax
0.583
0.623
1.638
0.769
0.792
1.475
Dc (g cm−3
)
Measured reflections
Unique reflections and Rint
Observed reflections
data/restraints/parameters
Goodness of fit on F2
R1 [I ≥ 2σ(I)]
10938
3044 and 0.0506
2203
3044/0/191
1.021
0.0401
4990
1923 and 0.0231
1547
1923/0/110
1.043
0.0397
wR2 [I ≥ 2σ(I)]
0.0804
0.0649
0.0952
0.0517
R1 (all data)
wR2 (all data)
Large diff. peak and hole (e Å−3
0.0896
0.338, –0.385
0.1018
0.613, –0.470
)

866
D.-H. SHI ET AL.
least-squares methods using the SHELXTL package (Sheidrick,
G.M., Madison, WI, USA).[12] All of the non-hydrogen atoms
were refined anisotropically. Hydrogen atoms were placed in
calculated positions and constrained to ride on their parent
atoms. The complex (2) is disordered about the twofold ro-
tation axis. The crystallographic data for the complexes are
summarized in Table 1. Selected bond lengths and angles are
given in Table 2. Crystallographic data for the complexes have
been deposited with the Cambridge Crystallographic Data Cen-
ter (CCDC 838625 for (1) and 838626 for (2)).
RESULTS AND DISCUSSION
The tridentate Schiff bases HL1 and L2 were prepared in
quantitative yields in methanol. The copper(II) and zinc(II)
complexes were prepared according to the same synthetic pro-
cedures. Both complexes crystallize in well-shaped single crys-
tals, which are stable in air at room temperature, and are sol-
uble in methanol, ethanol, and acetonitrile. It is well known
that the pseudohalide anions such as azide and thiocyanate
readily bridge different metal atoms, forming polynuclear com-
plexes,[13–16] however, in the present work, the azide and thio-
cyanate anions coordinate to the metal atoms through terminal
coordination mode.
FIG. 1. Molecular structure of (1) at 30% probability ellipsoids.
Structure Description of Complex (1)
Figure 1 gives perspective view of complex (1). The com-
plex is a centrosymmetric phenolate oxygen bridged dinu-
clear copper(II) compound, with the inversion center located
at the midpoint of the two Cu atoms. The Cu···Cu dis-
tance is 3.182(2) Å. The Cu atom in the complex is five-
coordinated in a distorted square-pyramidal coordination, with
the three donor atoms of L1 and one azide N atom defin-
ing the basal plane, and with one phenolate O atom occu-
pying the apical position. The distortion of the coordination
geometry can be calculated by the τ value, a reference to de-
scribe the degree of distortion for square-pyramid and trigonal-
bipyramid [square pyramid, τ = 0; trigonal bipyramid, τ = 1;
τ = (β – α)/60◦, α and β are the two largest angles around the
central atom].[17] The τ value for the complex is 0.068. Hence,
the coordination of the Cu atom in the complex can be best
described as a slightly distorted square-pyramid, rather than
trigonal-bipyramid. The coordinate bond lengths and angles in
the complex are comparable to those observed in other similar
Schiff base copper(II) complexes.[18,19]
TABLE 2
Selected bond lengths (Å) and angles (◦) for the complexes
(1)
Bond lengths
Cu1-O1
1.9226(19)
2.004(2)
2.377(2)
Cu1-N1
Cu1-N3
1.974(2)
1.963(3)
Cu1-N2
Cu1-O1i
Bond angles
O1-Cu1-N3
N3-Cu1-N1
N3-Cu1-N2
O1-Cu1-O1i
N1-Cu1-O1i
(2)
95.67(10)
167.52(11)
92.56(10)
85.11(8)
O1-Cu1-N1
O1-Cu1-N2
N1-Cu1-N2
N3-Cu1-O1i
N2-Cu1-O1i
90.40(9)
171.56(9)
81.89(10)
99.62(9)
91.65(8)
91.73(8)
Bond lengths
Zn1-N1
Structure Description of Complex (2)
2.155(2)
1.975(3)
1.975(3)
Zn1-N2
2.084(3)
2.155(2)
Figure 2 gives perspective view of complex (2). The com-
plex is a mononuclear zinc(II) compound. The Zn atom in the
complex is five-coordinated in a distorted square pyramidal co-
ordination, with the three N donor atoms of L2, and with one
thiocyanate N atoms defining the basal plane, and with another
thiocyanate N atom occupying the apical position. The τ value
for the complex is 0.413. Hence, the coordination of the Zn atom
in the complex can be best described as a severely distorted
square-pyramid, rather than trigonal-bipyramid. The coordinate
bond lengths and angles in the complex are comparable to those
observed in other similar Schiff base zinc(II) complexes.[20,21]
Zn1-N3
Zn1-N1ii
Zn1-N3ii
Bond angles
N3-Zn1-N3ii
N3-Zn1-N2
N2-Zn1-N1ii
N3-Zn1-N1
N1-Zn1-N1ii
105.27(16)
127.36(8)
76.08(7)
100.16(10)
152.15(14)
N3-Zn1-N2ii
N3-Zn1-N1ii
N3-Zn1-N1ii
N2-Zn1-N1
127.36(8)
96.64(10)
96.64(10)
76.08(7)
Symmetry operations for equivalent atoms: i) –x, 1 – y, –z; ii) 1 –
x, y, 1/2 – z.

COPPER(II) AND ZINC(II) COMPLEXES
867
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