Synthesis and characterization of metal complexes with unsymmetrical tetradentate schiff base ligand

Article abstract of DOI:10.1081/SIM-120035950

A new unsymmetrical tetradentate Schiff base ligand (H₂L) was synthesized using 5-chloro-2-hydroxybenzophenone, o-phenylenediamine, and salicylaldehyde. Five metal complexes of this ligand, [ML]·xH ₂O (M = Cu(II), Ni(II), Zn(II), Mn(II), and Co(II); x = 0-3), have been prepared and characterized by elemental analyses, IR spectra, UV spectra, and molar conductance. Possible structures of these complexes have been proposed.

Full text of DOI:10.1081/SIM-120035950

This article was downloaded by: [Dicle University]
On: 16 November 2014, At: 05:32
Publisher: Taylor & Francis
Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer
House, 37-41 Mortimer Street, London W1T 3JH, UK
Synthesis and Reactivity in Inorganic and Metal-
Organic Chemistry
Publication details, including instructions for authors and subscription information:
http://www.tandfonline.com/loi/lsrt19
Synthesis and Characterization of Metal Complexes
with Unsymmetrical Tetradentate Schiff Base Ligand
Caifeng Bi a & Yuhua Fan a b
a College of Chemistry and Chemical Engineering , Ocean University of China , Qingdao,
266003, China
b China Institute of Atomic Energy , Beijing, China
Published online: 16 Nov 2010.
To cite this article: Caifeng Bi & Yuhua Fan (2004) Synthesis and Characterization of Metal Complexes with Unsymmetrical
Tetradentate Schiff Base Ligand, Synthesis and Reactivity in Inorganic and Metal-Organic Chemistry, 34:4, 687-695, DOI:
10.1081/SIM-120035950
To link to this article: http://dx.doi.org/10.1081/SIM-120035950
PLEASE SCROLL DOWN FOR ARTICLE
Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained
in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no
representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of
the Content. Any opinions and views expressed in this publication are the opinions and views of the authors,
and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied
upon and should be independently verified with primary sources of information. Taylor and Francis shall
not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other
liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or
arising out of the use of the Content.
This article may be used for research, teaching, and private study purposes. Any substantial or systematic
reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any
form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http://
www.tandfonline.com/page/terms-and-conditions

SYNTHESIS AND REACTIVITY IN INORGANIC AND METAL-ORGANIC CHEMISTRY
Vol. 34, No. 4, pp. 687–695, 2004
Synthesis and Characterization of Metal
Complexes with Unsymmetrical
Tetradentate Schiff Base Ligand
1,2
Caifeng Bi1, and Yuhua Fan
*
1College of Chemistry and Chemical Engineering, Ocean University
of China, Qingdao, China
2China Institute of Atomic Energy, Beijing, China
ABSTRACT
A new unsymmetrical tetradentate Schiff base ligand (H2L) was syn-
thesized using 5-chloro-2-hydroxybenzophenone, o-phenylenediamine,
.
and salicylaldehyde. Five metal complexes of this ligand, [ML] xH2O
(M ¼ Cu(II), Ni(II), Zn(II), Mn(II), and Co(II); x ¼ 0–3), have been pre-
pared and characterized by elemental analyses, IR spectra, UV spectra,
and molar conductance. Possible structures of these complexes have
been proposed.
Key Words: Metal complexes; Schiff base ligand; Macrocycle model;
Unsymmetric complex.
*
Correspondence: Caifeng Bi, College of Chemistry and Chemical Engineering, Ocean
University of China, Qingdao 266003, China; E-mail: bcfeng@mail.ouc.edu.cn.
687
DOI: 10.1081/SIM-120035950
0094-5714 (Print); 1532-2440 (Online)
www.dekker.com
Copyright # 2004 by Marcel Dekker, Inc.

ORDER
REPRINTS
688
Bi and Fan
INTRODUCTION
Symmetric tetradentate Schiff base complexes have been used exten-
sively as macrocycle models,[1] while unsymmetric complexes are very
important in biological systems and in industrial catalysis.[2,3] Recently,
studies of some metal complexes with unsymmetrical Schiff bases derived
form acetylacetone, ethylenediamine, and salicylaldehyde have been
reported.[4,5] To continue the investigation in this area, a new unsymmetrical
Schiff base ligand has been synthesized starting from 5-chloro-2-hydroxy-
benzophenone, o-phenylenediamine, and salicylaldehyde. Since this ligand
dose not exist in the literature, this paper deals with the preparation and
characterization of the complexes formed from this Schiff base ligand (see
Fig. 1) with Cu(II), Ni(II), Zn(II), Mn(II), and Co(II).
EXPERIMENTAL
Reagents
All reagents used in this work were of analytical grade. 5-Chloro-2-
hydroxybenzophenone was prepared by the reaction of benzoyl chloride
with 4-chlorophenol in the presence of anhydrous aluminum trichloride.[4]
Preparation of Ligand
Mono-Schiff Base (HCBP-DABZ)
o-Phenylenediamine (18.50 g, 171 mmol) dissolved in 150 mL anhydrous
ethanol was mixed with piperidine (1.50 g, 17.6 mmol), triethyl orthoformate
(25.2 g, 170 mmol), and 5-chloro-2-hydroxybenzophenone (39.80 g,
171 mmol) and refluxed for 6 hr to give an orange–red precipitate. The pre-
Figure 1. Structure of the ligand.

ORDER
REPRINTS
Metal Complexes
689
cipitate was collected by filtration washed with ethanol and dried in a vacuum.
Yield, 36.2 g (65.6%); mp: 193–194 8C.
Unsymmetrical Schiff Base (H2L)
HCBP-DABZ (4.00 g, 12.4 mmol) dissolved in 150 mL methanol was
mixed with salicylaldehyde (1.52 g, 12.4 mmol) and refluxed for 4 hr to give
an orange–yellow precipitate. The precipitate was filtered, recrystallized
with methanol, and dried in a vacuum. Yield, 4.24 g (80%); mp: 302–303 8C.
Preparation of Complexes
The unsymmetrical Schiff base (1.71 g, 4.0 mmol) dissolved in 60 mL
n-butyl alcohol was mixed with the metal acetate (4.0 mmol) dissolved in
20 mL methanol and refluxed for 4 hr to give a precipitate. The precipitate
was filtered, recrystallized from methanol, and dried in a vacuum. The purity
of the complexes was higher than 99%.
Physical Measurement
Elemental analyses were carried out with a model 2400 Perkin–Elmer
analyzer. The metal content was determined gravimetrically. The ultraviolet
spectra were recorded on a Shimadzu UV-3000 spectrophotometer in
DMSO. The molar conductance was measured with a Shanghai DDS-11A
conductivity meter. Infrared spectra of the ligand and complexes were
recorded in KBr pellets using a Bio-Rad FTS 165 spectrophotometer. Thermo-
gravimetric measurements were made using a Perkin–Elmer TGA7 instru-
ment. The heating rate was programmed to be 10 8C min21 with a
protecting stream of N2 flowing at a rate of 40 mL min21. The mass spectro-
gram of the ligand was recorded on a Finnegan MAT-212 mass spectrometer.
RESULTS AND DISCUSSION
The synthesis reactions of the ligand are shown in Fig. 2.
The synthesis reaction of the complexes may be represented as shown below.
MðOAcÞ2 ꢀ nH2O þ H2L ꢁ!ML ꢀ xH2O þ 2HOAc þ ðn ꢁ xÞH2O
The results of the elemental analyses and molar conductance data are
shown in Table 1. The molar conductance values of the complexes measured

ORDER
REPRINTS
690
Bi and Fan
Figure 2. Preparation of the ligand.
in DMSO in 1023 mol L21 solution fall in the range 8.29–18.6 S cm2 mol21
indicating their non-electrolytic nature.[6] The complexes are stable in air
and soluble in DMF and DMSO; however, they are insoluble in benzene,
acetone, diethyl ether, and water.
Mass Spectra
The mass spectra of HCBE-DABZ and H2L are shown in Fig. 3. The data
of the molecular weights indicate that the reaction product (HCBE-DABZ)
of 5-chloro-2-hydroxybenzophenone with 1,2-diaminobenzene is a mono-
Schiff base and H2L prepared from HCBE-DABZ and salicylaldehyde is an
unsymmetrical di-Schiff base.
IR Spectra
The infrared spectra of the ligand and its complexes are shown in Table 2.
The shift of n(C55N) from 1630.4 cm21 in the ligand to very strong absorption
bands in the region 1602.7–1611.1 cm21 in the complexes, suggests the for-
mation of a C55N–M band system. The vibration n(C–O) of H2L occurs at
1209.1cm21. The shift to lower frequency by about 20 cm21 in the metal

ORDER
REPRINTS
Metal Complexes
691

ORDER
REPRINTS
692
Bi and Fan
Figure 3. Mass spectra of unsymmetrical Schiff base and mono-Schiff base.
Table 2. Main IR bands of ligand and complexes (cm21).
Compounds
n(O–H)
n(C55N)
n(C–O)
n(O–M)
n(N–M)
H2L
CuL
3116.9 s
1630.4 s
1602.7 s
1611.1 s
1610.7 s
1607.1 s
1605.6 s
1209.1 m
1180.6 m
1179.3 m
1187.8 m
1195.4 m
1179.0 m
420.25 w
416.28 w
413.52 w
447.46 w
420.25 w
539.36 w
547.63 w
527.09 w
542.52 w
539.24 w
.
[NiL] H2O
.
[ZnL] 3H2O
3127.2
3151.3 s
3151.7 s
3117.2 s
.
[MnL] H2O
.
[CoL] H2O

ORDER
REPRINTS
Metal Complexes
693
Table 3. UV spectra for ligand and complexes.
lmax1
(nm)
11 ꢂ 1024
lmax2
(nm)
12 ꢂ 1024
Compounds
(L mol21 cm21
)
(L mol21 cm21
)
H2L
CuL
258
262
265
263
262
266
0.642
2.56
4.26
3.25
0.983
2.55
342
344
348
346
348
349
0.425
1.76
2.96
.
[NiL] H2O
.
[ZnL] 3H2O
0.682
0.334
1.66
.
[MnL] H2O
.
[CoL] H2O
complexes indicates the coordination of oxygen to metal ions. In the spectra of
the complexes, the occurrence of bands at 413–448cm21 (M–O) and 527–
548 cm21 (M–N) provides evidence for the bonding of oxygen and nitrogen
to the central metal ion.[7] The spectra of the Ni(II), Zn(II), Mn(II), and Co(II)
complexes exhibit a broad band at 3117.2–3157.1 cm21, which is attributed to
n(O–H) of the water molecules of crystallization.[8]
Electronic Spectra
The spectral data are shown in Table 3. The electronic spectra of the com-
plexes in DMSO exhibit the same two spectral bands in the regions at 262–
266 and 344–349 nm, which are also observed in the spectrum of the ligand.
Table 4. Thermal analysis data of the complexes.
Weight loss (%)
by TG
Temperature
range (8C)
Final
products
Complex
CuL
Found
Calcd.
Assignment
265–343
62–125
235–370
69–139
240–409
65–128
210–371
60–120
223–395
83.38
3.70
83.71
3.59
–L
–H2O
–L
CuO
NiO
.
[NiL] H2O
81.41
9.70
81.52
9.93
.
[ZnL] 3H2O
–3H2O
–L
ZnO
MnO
CoO
75.38
3.68
75.11
3.62
.
[MnL] H2O
–H2O
–L
82.32
3.48
81.39
82.13
3.59
81.48
.
[CoL] H2O
–H2O
–L

ORDER
REPRINTS
694
Bi and Fan
Figure 4. Suggested structure of the complexes.
Compared with the electronic spectrum of the ligand, there is a shift to lower
frequency, which further testifies to the formation of complexes.
Thermal Decomposition Studies
The DTG-TG curves of the complexes were determined in a stream of N2
at a flow rate of 40 mL min21. The thermal analysis data of the complexes are
shown in Table 4. The Cu(II) complex gave a one-stage decomposition
pattern, which corresponds to the loss of the ligand molecule. The other com-
plexes decompose in two steps. The first decomposition step corresponds to
the loss of water molecules. The fact that the water molecules were lost at a
low temperature suggests that the water is crystal water. The second step cor-
responds to the loss of ligand molecule. In all cases, the final products are
metal oxides. The total weight loss is in agreement with the composition of
the complexes.
Finally, the results presented here clearly indicate that Cu(II), Ni(II),
Zn(II), Mn(II), and Co(II) can from stable solid complexes with H2L. The
structure proposed for the complexes is shown in Fig. 4.
REFERENCES
1. Krakowiak, K.E.; Bradshow, J.S. Synthesis and catalytic properties of
ruthenium(III) unsymmetrical Schiff base complexes. Bull. Chem. Soc.
1992, 13 (3), 156–160.
2. George, W.; Gokel, D.M. Metal complexes with unsymmetrical tetradentate
Schiff bases. Inorg. Chim. Acta 1984, 82, 101–109.

ORDER
REPRINTS
Metal Complexes
695
3. Kwiatkowowski, E.; Kwiatkowski, M. Unsymmetrical Schiff base com-
plexes of nickel(II) and palladium(II). Inorg. Chim. Acta 1980, 42, 197–202.
4. Yuling, Z.; Wenjuan, R.; Guohang, H.; Zhiang, Z. Synthesis and spectra
properties of novel binuclear Schiff base complexes. Chin. J. Inorg.
Chem. 2002, 18 (9), 902–906.
5. Ting, T.; Yuqiu, G. Synthesis and character of new mixed-ligand complexes
of copper(II) with Schiff base. Chin. J. Inorg. Chem. 2001, 17 (5), 745–750.
6. Geary, W.J. The use of Conductivity measurements in organic solvents for
the characterization of coordination compounds. Coor. Chem. Rev. 1971,
7, 81–122.
7. Fiol, J.J.; Terron, A.; Mulet, D.; Moreno, V. Some new derivatives of
Co(III) with uracil, uridine and pyrimidine nucleotides. Inorg. Chim.
Acta 1987, 135, 197–202.
8. Stefan, S.L.; EL-Shetary, B.A.; Hanna, W.G.; El-Maraghy, S.B.; Moez, M.S.
Determination of some lanthanide ions by conductometric and spectrophoto-
metric measurements of their hydrazo-5-pyrazolone complexes. Microchem.
J. 1987, 35 (1), 51–65.
Received June 3, 2003
Accepted January 2, 2004
Referee I: H. G. Ritchey, Jr.
Referee II: P. J. Toscano

Request Permission or Order Reprints Instantly!
Interested in copying and sharing this article? In most cases, U.S. Copyright
Law requires that you get permission from the article’s rightsholder before
using copyrighted content.
All information and materials found in this article, including but not limited
to text, trademarks, patents, logos, graphics and images (the "Materials"), are
the copyrighted works and other forms of intellectual property of Marcel
Dekker, Inc., or its licensors. All rights not expressly granted are reserved.
Get permission to lawfully reproduce and distribute the Materials or order
reprints quickly and painlessly. Simply click on the "Request Permission/
Order Reprints" link below and follow the instructions. Visit the
U.S. Copyright Office for information on Fair Use limitations of U.S.
copyright law. Please refer to The Association of American Publishers’
Fair Use in the Classroom.
(AAP) website for guidelines on
The Materials are for your personal use only and cannot be reformatted,
reposted, resold or distributed by electronic means or otherwise without
permission from Marcel Dekker, Inc. Marcel Dekker, Inc. grants you the
limited right to display the Materials only on your personal computer or
personal wireless device, and to copy and download single copies of such
Materials provided that any copyright, trademark or other notice appearing
on such Materials is also retained by, displayed, copied or downloaded as
part of the Materials and is not removed or obscured, and provided you do
not edit, modify, alter or enhance the Materials. Please refer to our
Website
User Agreement for more details.
Request Permission/Order Reprints
Reprints of this article can also be ordered at
http://www.dekker.com/servlet/product/DOI/101081SIM120035950