Preparation and thermal, spectroscopic, and antibacterial studies of some mixed-ligand complexes

Article abstract of DOI:10.1081/SIM-120039268

The present investigation reports the synthesis, characterization, and antibacterial activities of some mixed-ligand complexes of the type [ML(SB)H₂O], where M = Mn(II), Co(II), Ni(II), Cu(II), Zn(II), and Cd(II), SB¹ = bis(benzylidene)ethylenediamine (benen) or SB ² = bis(acetophenone)ethylenediamine (acphen) and KHL = potassium salt of salicylideneglycine (salgly). Their structures have been elucidated on the basis of elemental analyses, thermogravimetric analyses, magnetic measurements, reflectance spectra, and IR spectra. The results are in accord with an octahedral environment around the central metal ion. The mixed-ligand complexes of Mn(II), Co(II), Ni(II), and Cu(II) are paramagnetic while the Zn(II) and Cd(II) complexes are diamagnetic. The mixed-ligand complexes have been tested against bacteria and the results are compared with a standard drug (tetracycline) and control (dimethyl sulfoxide).

Full text of DOI:10.1081/SIM-120039268

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Preparation and Thermal, Spectroscopic, and
Antibacterial Studies of Some Mixed‐Ligand
Complexes
Pragnesh K. Panchal a , D. H. Patel b & M. N. Patel a
a Department of Chemistry, Sardar Patel University, Vallabh Vidyanagar, Gujarat, 388
120, India
b Department of Biosciences, Sardar Patel University, Vallabh‐Vidyanagar, Gujarat, India
Version of record first published: 16 Nov 2010.
To cite this article: Pragnesh K. Panchal , D. H. Patel & M. N. Patel (2004): Preparation and Thermal, Spectroscopic, and
Antibacterial Studies of Some Mixed‐Ligand Complexes, Synthesis and Reactivity in Inorganic and Metal-Organic Chemistry,
34:7, 1223-1235
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SYNTHESIS AND REACTIVITY IN INORGANIC AND METAL-ORGANIC CHEMISTRY
Vol. 34, No. 7, pp. 1223–1235, 2004
Preparation and Thermal, Spectroscopic,
and Antibacterial Studies of Some
Mixed-Ligand Complexes
Pragnesh K. Panchal,1 D. H. Patel,2 and M. N. Patel1,
*
1Department of Chemistry and 2Department of Biosciences, Sardar Patel
University, Vallabh-Vidyanagar, Gujarat, India
ABSTRACT
The present investigation reports the synthesis, characterization, and anti-
bacterial activities of some mixed-ligand complexes of the type
[ML(SB)H2O], where M ¼ Mn(II), Co(II), Ni(II), Cu(II), Zn(II), and
Cd(II), SB1 ¼ bis(benzylidene)ethylenediamine (benen) or SB2 ¼
bis(acetophenone)ethylenediamine (acphen) and KHL ¼ potassium salt
of salicylideneglycine (salgly). Their structures have been elucidated on
the basis of elemental analyses, thermogravimetric analyses, magnetic
measurements, reflectance spectra, and IR spectra. The results are in
accord with an octahedral environment around the central metal ion.
The mixed-ligand complexes of Mn(II), Co(II), Ni(II), and Cu(II) are
paramagnetic while the Zn(II) and Cd(II) complexes are diamagnetic.
The mixed-ligand complexes have been tested against bacteria and the
*
Correspondence: M. N. Patel, Department of Chemistry, Sardar Patel University,
Vallabh Vidyanagar, Gujarat 388 120, India; E-mail: jeenenpatel@yahoo.co.in.
1223
DOI: 10.1081/SIM-120039268
0094-5714 (Print); 1532-2440 (Online)
www.dekker.com
Copyright # 2004 by Marcel Dekker, Inc.

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Panchal, Patel, and Patel
results are compared with a standard drug (tetracycline) and control
(dimethyl sulfoxide).
Key Words: Mixed-ligand complexes; Schiff bases; Tetracycline;
Dimethyl sulfoxide.
INTRODUCTION
The coordination chemistry of amino acid-Schiff base ligands is of consi-
derable interest due to their biological importance.[1,2] Especially, because it
has been reported that the mixed-ligand complexes of amino acid-Schiff base
with transition elements are used as radiotracers in nuclear medicine[3] and as
antitumor[4] agents. Moreover, in many cases, it has been suggested that some
biological activities of organic compounds can be increased by coordination
with transition elements. In continuation of earlier work[5] we report here the
mixed-ligand complexes of Mn(II), Co(II), Ni(II), Cu(II), Zn(II), and Cd(II)
with two Schiff bases. The structures of the Schiff bases are shown in Fig. 1.
EXPERIMENTAL
All the chemicals and solvents used were of analytical grade. Metal chlor-
ides, salicylaldehyde, benzaldehyde, acetophenone, ethylenediamine, and
glycine were purchased from the E. Merck (India) Limited, Mumbai. The
organic solvents were purified by recommended methods.[6]
Figure 1. Structure of the Schiff bases.

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Mixed-Ligand Complexes
Preparation of Schiff Bases
Potassium Salt of Salicylideneglycine (Salgly)
1225
A solution of potassium hydroxide (10 mmol, 0.56 g) in 30 mL absolute
alcohol was added to crystalline glycine (10 mmol, 0.75 g). The mixture
was stirred until it had completely dissolved in the ethanol–KOH solution.
Then an ethanolic solution (100 mL) of salicylaldehyde (10 mmol, 1.22 g)
was added quickly. The reaction was allowed to come to completion by
stirring at 50 8C for 1 hr. The product was crystallized by diffusion of
excess absolute diethyl ether into the solution. The resulting product was
filtered and dried in a vacuum desiccator. Yield: 1.59 g (63%), M.p.: 207 8C.
Bis(acetophenone)ethylenediamine (Acphen)
An ethanolic solution (100 mL) of ethylenediamine (10 mmol, 0.60 g)
and an ethanolic solution (100 mL) of acetophenone (20 mmol, 2.40 g) in
the mole ratio 1 : 2 was mixed with constant stirring at room temperature.
Refluxing was carried out for 5 hr at 80 8C and then the mixture was
cooled in a refrigerator at 0–2 8C for overnight. A fine, yellow product was
formed. The product was filtered and dried in air. Yield: 2.28 g (76%),
M.p.: 260 8C.
Bis(benzylidene)ethylenediamine (Benen)
The bis(benzylidene)ethylenediamine (benen) was synthesized by a
published procedure.[7]
Synthesis of the Mixed-Ligand Complexes
The preparation of mixed-ligand complexes was carried out by mixing
an aqueous solution (100 mL) of metal chloride (10 mmol) and a hot
methanolic solution (100 mL) of the potassium salt of salgly (10 mmol,
2.17 g) and benen (10 mmol, 2.36 g) or acphen (10 mmol, 2.64 g) in 1 : 1 : 1
mole ratio. The mixed-ligand complexes were formed by heating the mixture
in a water bath for 1–2 hr at 50 8C. The mixture was kept overnight at room
temperature. A fine, coloured product was formed. The obtained crystals
were collected by filtration, washed with water and with ethanol, and
dried in air.

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Panchal, Patel, and Patel
Physical Measurements
The magnetic moments have been determined by a model 7304, Vibrating
Sample Magnetometer, Lake Shore, USA. Infrared spectra were recorded on a
FT-IR Nicolet 400D spectrophotometer. Carbon, hydrogen, and nitrogen were
analyzed with a model 240 Perkin–Elmer elemental analyzer. The metal
contents of the mixed-ligand complexes were analyzed by EDTA titration[8]
after decomposing the organic matter with a mixture of perchloric, sulfuric,
and nitric acid (1 : 1.5 : 2.5). Thermogravimetric analyses have been obtained
with a model 5000/2960 SDTA, TA Instruments, USA instrument. The reflec-
tance spectra of the mixed-ligand complexes were recorded in the range
1700–350 nm (as MgO discs) on a Beckman DK-2A spectrophotometer.
RESULTS AND DISCUSSION
The elemental analytical results and some physical properties of the
mixed-ligand complexes are listed in Table 1. The elemental analyses indicate
that the mixed-ligand complexes have the general formula [ML(SB)H2O]. All
the mixed-ligand complexes are insoluble in methanol, diethyl ether, and
dimethyl formamide but soluble in dimethyl sulfoxide. The mixed-ligand
complexes were synthesized following the general procedures outlined by
the following equations.
MCl2 ꢀ nH2O þ KHL þ benen
ꢁ! ½MLðbenenÞH2Oꢂ þ KCl þ HCl þ ðn ꢁ 1ÞH2O
MCl2 ꢀ nH2O þ KHL þ acphen
ꢁ! ½MLðacphenÞH2Oꢂ þ KCl þ HCl þ ðn ꢁ 1ÞH2O
Magnetic Measurement
The magnetic moment values of the Mn(II) complexes (5.90 and
5.93 B.M.) are as expected for a high-spin 3d5 system. These values are
very close to the spin-only value, which is 5.92 B.M., but within the limits
of the spin-free value for five unpaired electrons indicating that the complexes
are six coordinated with an octahedral geometry around the Mn(II) ion.[9] The
magnetic moment values for the Co(II) complexes have been used as
criteria to determine the type of coordination around the metal ion. Due
to the intrinsic orbital angular momentum in the ground state, there is

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Mixed-Ligand Complexes
1227
m

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1228
Panchal, Patel, and Patel
m

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Mixed-Ligand Complexes
1229
consistently a considerable orbital contribution and the effective magnetic
moment values of the Co(II) complexes (4.10 and 4.09 B.M.) are slightly
greater than the spin-only value (3.87 B.M.), which suggest an octahedral
geometry for the Co(II) complexes[10] in the high-spin state. The magnetic
moment values of the Ni(II) complexes are 3.18 and 3.08 B.M., which are
close to the spin-only value (2.83 B.M.) for octahedral Ni(II) complexes.[11]
The magnetic moment values of the Cu(II) complexes are 1.96 and
1.99 B.M., which are close to the spin-only value (1.73 B.M.) expected for
one unpaired electron, which offers the possibility of an octahedral geo-
metry.[12] The magnetic moment determination shows that the Zn(II) and
Cd(II) complexes are diamagnetic.
Infrared Spectra
All IR spectra exhibit a broad band in the region 3400–3000 cm21
,
suggesting the presence of coordinated water molecules.[13] The weak bands
around 850 and 710 cm21 are assigned as n(OH) rocking and wagging
vibrations, respectively.[14] The formation of the Schiff bases is confirmed
by the presence of a band specific for n(C55N) and the subsequent disappear-
ance of bands due to aldehydic and amino groups. IR spectra of the Schiff
bases exhibit a band at ꢀ1645 cm21 due to the azomethine group which
undergoes a shift to a lower frequency 10–15 cm21 on complexation, indicat-
ing the coordination of the azomethine nitrogen to the metal atom.[15] The
two absorption bands occurring near 1595 and 1400 cm21 in the Schiff base
corresponding to the asymmetric and symmetric stretching vibration bands
of the ionic carboxy group n(COO) in the complexes are shifted to lower
frequencies ꢀ1585 and ꢀ1390 cm21, respectively.[16] The n(O–H) band
originally found in the Schiff base disappeared on complexation indicating
deprotonation of the phenolic hydroxyl group and coordination of phenolic
oxygen to the metal. This is further supported by the shift in the stretching
frequency of the phenolic n(C–O)[17] at 1530 cm21 to the higher side by
ꢀ10–20 cm21. In the low-frequency region, the bands observed in the
region of ꢀ525–535 cm21 are attributed to n(M–N),[18] in the region of
ꢀ460–470 cm21 to n(M–O)phenolic , and in the region of ꢀ415–420 cm21
[19]
to n(M–O)carboxy
.
The IR data suggest that the metal ion is bonded to
the Schiff bases through the carboxylate oxygen, the phenolic oxygen, and
azomethine group as well as the water molecule. The sharp bands in the
range 750–780 and 1525–1535 cm21 are due to aromatic n(C–H)[20] and
n(C55C),[21] respectively. The bands in the range 1475–1480 cm21 and
1370–1380 cm21 are due to n(C–H) of alkane and n(C–CH3), respectively.

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Panchal, Patel, and Patel
Electronic Spectra
6
The ground state of the Mn(II) is A1g. Mn(II) complexes in an
octahedral[22] field should have three transitions corresponding to
4
6
4
6A1g ! T1g (n1 ꢀ15,000cm21), A1g ! T2g (n2 ꢀ19,800cm21),
4
4
6A1g ! Eg, A1g (n3 ꢀ24,300cm21) in increasing order of energy. The
Co(II) complexes exhibit three spin-allowed bands, which can be assigned
to T1g ! T2g (n1 ꢀ9,400 cm21), T1g ! A2g (n2 ꢀ17,800cm21), and
4
4
4
4
4
4T1g ! T1g(P) (n3 ꢀ19,100cm21) transitions, respectively. The electronic
spectra of the complexes exhibited three bands and their position indicates
an octahedral geometry around Co(II).[23] The electronic spectra of the Ni(II)
complexes are composed of three absorption bands: the first band appeared
around n1 ꢀ10,550cm21 and is assigned to the A2g ! T2g transition, the
3
3
second is observed at n2 ꢀ17,400cm21 is attributed to the A2g ! T1g
3
3
transition, and the third one is located at n3 ꢀ25,100cm21 and is due to the
3
3A2g ! T1g(P) transition, respectively, in an octahedral[24] environment. The
ligand field splitting energy (10 Dq), interelectronic repulsion parameter (B),
and covalency factor (nephelauxetic ratio) (b) for the Co(II) and Ni(II)
[25]
¨
complexes have been calculated using the secular equations given by Konig.
For the Co(II) complexes:
1
1=2
10 Dq ¼ ½ð2n1 ꢁ n3Þ þ ðn23 þ n1n3 ꢁ n12Þ
ꢂ
2
15B ¼ n3 ꢁ 2n1 þ 10 Dq
B
b ¼ ½B0ð free ionÞ ¼ 971ꢂ
B0
b0 ¼ ð1 ꢁ bÞ100
For the Ni(II) complexes:
10 Dq ¼ n1
15B ¼ ðn2 þ n3Þ ꢁ 3n1
B
b ¼ ½B0ð free ionÞ ¼ 1030ꢂ
B0
b0 ¼ ð1 ꢁ bÞ100
The calculated electronic parameter values of the Co(II) and Ni(II) mixed-
ligand complexes are presented in Table 2. The Cu(II) complexes show one
2
2
band appearing around n1 ꢀ10,550cm21 due to the Eg ! T2g transition
suggesting an octahedral structure for the Cu(II) complexes.[26]

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Mixed-Ligand Complexes
1231
Table 2. Electronic spectral data of the Co(II) and Ni(II) complexes.
Observed band (cm21
)
Mixed-ligand complexes
n1
n2
n3
n2/n1
B
b
b0 10 Dq
[Co(L)(benen)(H2O)]
[Ni(L)(benen)(H2O)]
[Co(L)(acephen)(H2O)]
9,025 18,050 19,035 2.00 742 0.76 24 10,145
10,310 17,325 25,110 1.68 767 0.74 26 10,310
9,090 18,205 19,155 2.00 746 0.77 23 10,217
[Ni(L)(acephen)(H2O)] 10,215 17,465 21,195 1.70 801 0.77 22 10,210
Note: KHL ¼ potassium salt of salicylideneglycine; benen ¼ bis(benzylidene)
ethylenediamine; acphen ¼ bis(acetophenone)ethylenediamine.
Thermogravimetric Analysis
It has been observed that all the mixed-ligand complexes show a loss
in weight corresponding to one water molecule in the range ꢀ150–180 8C
indicating that this water molecule is coordinated to the metal ion.[27] In
the temperature range 180–600 8C the ligand molecules are lost. In all
the cases the final products are metal oxides. These results are in good accord-
ance with the composition of the mixed-ligand complexes. The suggested
structure of the mixed-ligand complexes are shown in Fig. 2.
Antibacterial Activity
Disc Diffusion Method
The antibacterial activity of the control (dimethyl sulfoxide), the standard
drug (tetracycline), the metal salts, the ligands, and their mixed-ligands com-
plexes were evaluated by the disc diffusion technique.[28] A stock solution of
250 mg/mL was made by dissolving 25 mg of each compound in dimethyl
Figure 2. Structure of the mixed-ligand complexes [ML(SB)H2O], where X ¼ H
(SB1) or CH3 (SB2).

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Panchal, Patel, and Patel
sulfoxide (100 mL). Filter paper (Whatman No. 4) discs (6 mm diameter) were
soaked in solutions (20 mL) of the test compounds and after drying, placed on
a nutrient agar plate containing lawn cultures of various bacteria. The plates
were incubated at an optimum growth temperature of 37 8C. The zones of inhi-
bition (in mm) around the discs were measured after 24 hr. The test bacteria
included (a) S. typhi, (b) E. coli, and (c) Serratia marcescens. The control
experiments were performed with equivalent volumes of solvents without
added test compounds which were applied to the paper discs and the
zone of inhibition was measured (in mm). All experiments were performed
in triplicate and tetracycline was used as a standard drug. The mixed-ligand
Table 3. Antibacterial activities of the complexes.
Zone of inhibition (in mm) (% inhibition)
Serratia
marcesens
Compounds
S. typhi
E. coli
12
DMSO (control)
Tetracycline
KHL
benen (SB1)
acphen (SB2)
9
15
18 (100.00)
10 (11.11)
11 (22.22)
11 (22.22)
10 (11.11)
10 (11.11)
11 (22.22)
11 (22.22)
10 (11.11)
11 (22.22)
13 (44.44)
14 (55.55)
13 (44.44)
13 (44.44)
11 (55.55)
13 (44.44)
12 (33.33)
14 (55.55)
13 (44.44)
13 (44.44)
14 (55.55)
13 (44.44)
21 (75.00)
13 (08.33)
14 (16.66)
13 (08.33)
13 (08.33)
13 (08.33)
14 (06.66)
13 (08.33)
14 (16.66)
14 (16.66)
15 (25.00)
17 (41.66)
16 (33.33)
17 (41.66)
18 (50.00)
16 (33.33)
16 (33.33)
18 (50.00)
15 (25.00)
15 (25.00)
17 (41.66)
16 (33.33)
26 (73.33)
17 (13.33)
17 (13.33)
16 (06.66)
16 (06.66)
17 (13.33)
16 (06.66)
17 (13.33)
17 (13.33)
17 (13.33)
20 (33.33)
23 (55.33)
19 (26.26)
19 (26.66)
21 (40.00)
22 (46.66)
19 (26.66)
22 (16.66)
20 (33.33)
23 (53.33)
23 (53.33)
21 (40.00)
.
MnCl2 4H2O
.
CoCl2 6H2O
.
NiCl2 6H2O
.
CuCl2 2H2O
ZnCl2
CdCl2 2H2O
.
[Mn(L)(benen)(H2O)]
[Co(L)(benen)(H2O)]
[Ni(L)(benen)(H2O)]
[Cu(L)(benen)(H2O)]
[Zn(L)(benen)(H2O)]
[Cd(L)(benen)(H2O)]
[Mn(L)(acphen)(H2O)]
[Co(L)(acphen)(H2O)]
[Ni(L)(acphen)(H2O)]
[Cu(L)(acphen)(H2O)]
[Zn(L)(acphen)(H2O)]
[Cd(L)(acphen)(H2O)]
Note: KHL ¼ potassium salt of salicylideneglycine; benen ¼ bis(benzylidene)
ethylenediamine; acphen ¼ bis(acetophenone)ethylenediamine.

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1233
complexes are soluble in dimethyl sulfoxide. Therefore, the growth was
compared with dimethyl sulfoxide as the control, and is expressed as zone
of inhibition and percentage inhibition versus control. The zone of inhibition
and percentage inhibition of the complexes are recorded in Table 3. From the
data it is observed that the mixed-ligand complexes show higher activity
against bacteria, as compared to the control (blank), the ligands, and the
metal salts. The mixed-ligand complexes show moderate activities as com-
pared to the standard drug (tetracycline). The results suggest that the changes
in structure due to the coordination in the mixed-ligand complexes decreases
the growth of microorganisms relative to the metal ion, the ligands, and the
control, hence, the complexation increases the antibacterial activity due to
the presence of three azomethine (C55N) groups.[29] The patterns of activity
are complex and no clear trend can be ascertained.
ACKNOWLEDGMENTS
We wish to express our sincere thanks to Prof. R. M. Patel, Head, Depart-
ment of Chemistry and Prof. M. Dutta, Head, Department of Biosciences,
Sardar Patel University, Vallabh Vidyanagar, India, for providing the necessary
laboratory facilities.
REFERENCES
1. Ray, R.K. Fe(III) complexes of salicylidene amino acid. J. Therm. Anal.
1990, 36 (2), 455–459.
2. Singh, N.K.; Singh, D.K.; Singh, S.B. Synthesis, characterization and
biological studies on Co(II), Ni(II), Cu(II) and Zn(II) complexes with
N-picolinoyl-N0-thiobenzoylhydrazine. Synth. React. Inorg. Met.-Org.
Chem. 2002, 32 (4), 703–720.
3. Du Preez, J.G.H.; Gerber, T.I.A.; Fourie, P.J.; Van Wyk, A.J. The
chemistry of rhenium and technetium. Part II. Schiff base complexes
with polyfunctional amino acids. J. Coord. Chem. 1984, 13, 173–178.
4. Singh, N.K.; Singh, N.; Sodhi, A.; Shrivastava, A.; Prasad, G.C.
Synthesis, characterization and antitumer studies on N-salicyl-
N0-thiobenzohydrazide. Trasit. Met. Chem. 1996, 21, 556.
5. Patel, K.M.; Patel, N.H.; Patel, K.N.; Patel, M.N. Synthesis, structural,
characterization and biocidal studies of Mn(II), Fe(II), Co(II), Ni(II),
Cu(II), Zn(II) and Cd(II) complexes with tridentate Schiff bases and
2,20-bipyridylamine. Synth. React. Inorg. Met.-Org. Chem. 2000,
30 (10), 1953–1963.

ORDER
REPRINTS
1234
Panchal, Patel, and Patel
6. Vogel, A.I. Textbook of Practical Organic Chemistry, 5th Ed.; Longman:
London, 1989.
7. Dholakiya, P.P.; Patel, M.N. Preparation, magnetic spectra and biocidal
studies of some transition metal complexes with 3,5-dibromosalicyli-
deneaniline and neutral bidentate ligands. Synth. React. Inorg. Met.-
Org. Chem. 2002, 32 (4), 819.
8. Vogel, A.I. A Text Book of Quantitative Inorganic Analyses; Longmans
Green: London, 1962.
9. Sahu, B.K.; Mahapatra, B.K. Mixed-ligand complexes of Mn(II) and
Cd(II) dithiocarbamates with nitrogen donors. J. Ind. Chem. Soc. 1979,
56 (1–12), 825–826; Chem. Abstr. 1980, 92, 156968g.
10. Lever, A.B.P. Inorganic Electronic Spectroscopy; Elsevier: Amsterdam,
1984.
11. Dutta, R.L.; Bhattacharya, A. Ni(II) mixed chelates containing two
bidentate monobasic hydroxyaldehyde (or ketone) and a bidentate (NN)
heterocycle. J. Ind. Chem. Soc. 1980, 5 (1–6), 428–429; Chem. Abstr.
1981, 94, 24198n.
12. Sutton, D. Electrostatic energy level diagrams and the spectra of
octahedral complexes. In Electronic Spectra of Transition Metal
Complexes; McGraw-Hill: London, 1968.
13. Theriot, L.J.; Carlisle, G.O.; Hu, H.J. Nickel(II) complexes of N-salicyli-
deneamino acids. J. Inorg. Nucl. Chem. 1969, 31 (9), 2891–2894.
14. Fuzita, L.; Nakamoto, K.; Kobayashi, M. Infrared spectra of metallic
complexes II. The absorption bands of coordinated water in aquo com-
plexes. J. Am. Chem. Soc. 1956, 78, 3963–3965.
15. Madhu, N.T.; Radhakrishnan, P.K. Co(II) complexes of 1,2-(diimino4-
antipyrinyl)ethane and 4-N-(40-antipyrylmethylidene)aminoantipyrine.
Trans. Met. Chem. 2000, 25, 287–292.
16. Saxena, V.K.; Gupta, M.; Srivastava, M.N. Synthesis and characterization
of complexes of Co(II), Ni(II), Cu(II) and Zn(II) with histidine and
glycine or alanine. Synth. React. Inorg. Met.-Org. Chem. 1996, 26 (10),
1661–1676.
17. Viswanathamurthi, P.; Dharmaraj, N.; Natarajan, K. Ruthenium(III)
complexes containing monofunctional bidentate Schiff bases. Synth.
React. Inorg. Met.-Org. Chem. 2000, 30 (7), 1273–1285.
18. Mohapatra, M.; Chakravortty, V.; Dash, K.C. Co(II) and Co(III) com-
plexes with hexadentate dioxime Schiff base ligands. Polyhedron 1989,
8 (12), 1509–1515.
¨
19. Koksal, H.; Tumer, M.; Serin, S. Synthesis and characterization of binuc-
lear Cu(II), Ni(II) and Co(II) chelates with tetradentate Schiff base ligands
derived from 1,5-diaminonaphthalene. Synth. React. Inorg. Met.-Org.
Chem. 1996, 26 (9), 1577–1588.

ORDER
REPRINTS
Mixed-Ligand Complexes
1235
20. Graber, S.J.; Harris, C.M.; Sinn, E. Metal complexes as ligands: bi and
tri-nuclear complexes derived from metal complexes of tridentate
salicylaldimines. J. Inorg. Nucl. Chem. 1968, 30, 1805–1830; Chem.
Abstr. 1968, 69, 73546s.
21. Sarma, B.D.; Bailar, J.C. Stereochemistry of metal chelates of a poly-
dentate ligand. J. Am. Chem. Soc. 1955, 77, 5476.
22. Patel, P.S.; Raj, R.M.; Patel, M.M. Synthesis and structural characteriz-
ation of Ni(II), Co(II), Zn(II), Mn(II), Cd(II) and U(VI) complexes of
a-oximinoacetoacet-o/p-anisidine thiosemicarbazone. Indian J. Chem.
Soc. 1993, 32, 597; Chem. Abstr. 1993, 119, 240317c.
23. Greenwood, N.N.; Earnshaw, A. Chemistry of the Elements, 2nd Ed.;
Butterworth-Heinemann: Oxford, 1997.
24. Kaul, B.B.; Pandeya, K.B. Substituted aniline and a-naphylamine carbo-
dithioatenickel(II) complexes and their pyridine adducts. J. Inorg. Nucl.
Chem. 1978, 40, 1035.
¨
25. Konig, E. The nephelauxetic effect. In Structure and Bonding; Springer
Verlag: Berlin, Heidelberg, New York, 1971; Vol. 9, 175–181.
26. Sacconi, L.; Ciampolini, M.; Campigli, U. Magnetic investigation of
some tetra-coordinated Ni(II) and Cu(II) complexes between 80 and
300 8K. Inorg. Chem. 1965, 4 (3), 407–409; Chem. Abstr. 1965, 62,
11728a.
27. Icbudak, H.; Yilmaz, V.T.; Olmez, H. Thermal studies on solid complexes
of saccharin with divalent transition metal ions. J. Therm. Anal. 1998, 53,
843–854.
28. Stokes, E.J.; Ridgway, G.L. In Clinical Bacteriology, 5th Ed.; Edward
Arnold Publisher: Baltimore, Maryland, USA, 1980; 205.
29. Popp, F.D. Synthesis of potential anticancer agent. II. Some Schiff bases.
J. Org. Chem. 1961, 26, 1566–1568.
Received September 24, 2003
Accepted March 15, 2004
Referee I: P. J. Toscano
Referee II: J. G. Wardeska

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