P M Yeole

P R Shirode

CiteSeerX

http://www.e-journals.in                                         Chemical Science Transactions 
DOI:10.7598/cst2014.801                                                              2014, 3(3), 1186-1192 
Synthesis and Characterization of Mixed Ligand Complexes 
of Transition Metals with Schiff’s Bases 
P. R. SHIRODE1 and P. M. YEOLE2 
1Department of Chemistry, Pratap College, Amalner, India 
2Centre for P.G. Research in Chemistry, R.L. College, Parola,  
Dist. Jalgaon North Maharashtra University, Jalgaon (Maharashtra), India 
prshirodepca@gmail.com 
Received 18 December 2013 / Accepted 17 January 2014 
Abstract: The mixed ligand complexes of the type [ML1L2]Cl2. Where M=Cr(III), Mn(II), Co(II), 
Ni(II) and Cu(II) and L1=Pyruvic acid  semicarbazone L2= Benzaldehyde semicarbazone have been 
synthesized, by the reactions of metal chlorides with two different  semicarbazones in 1:1:1 molar 
ratios. The resulting products have been characterized on the basis of elemental analysis, magnetic 
measurement, IR and Electronic spectra, conductivity measurement, thermal analysis, antimicrobial 
activities. The metal complexes show ratio 1:1:1 with metal, ligand L1 and ligand L2.The ligands are 
bonded through oxygen and nitrogen to metal ion.  
Keywords: Mixed ligand, Pyruvic acid semicarbazone, Benzaldehyde semicarbazone, Transition 
metals 
Introduction 
Semicarbazones shows a wide range of bioactivities and their chemistry and 
pharmacological applications have been extensively studied. The biological properties of 
semicarbazones are often related to metal ion coordination. Firstly, lipophilicity, which 
controls the rate of entry into the cell, is modified by coordination1. Also, the metal complex 
can be more active than the free ligand. The mechanism of action can involve binding to a 
metal in vivo or the metal complex may be a vehicle for activation of the ligand as the 
cytotoxic agent. Moreover, coordination may lead to significant reduction of drug-resistance2. 
A variety of 5-nitrofuryl semicarbazone derivatives have been developed for the therapy of 
Chagas disease, a major problem in the Central and the South America3. 4-Bromobenzal-
dehyde semicarbazone has been used as anticonvulsant. Recently, a review reported on the 
anticonvulsant activity of thiosemicarbazones, semicarbazones and hydrazones derived from 
aromatic and unsaturated carbonyl compounds as well as from other precursors4. In contrast 
to thiosemicarbazones, literature records fewer examples of semicarbazones presenting 
significant anticancer and cytotoxic activity but some nitro so, naphtopyran and fluorine 
derivatives showed  anti-leukemia  effect  in  mice5. Several N4- substituted semicarbazone 
 RESEARCH ARTICLE 
Chem Sci Trans., 2014, 3(3), 1186-1192                1187 
derivatives of o- and p- chlorobenzaldehyde and 2,6-dichlorobenzaldehyde exhibit potent 
anti-hypertensive effects6. The orally administered drug naftazone (1,2-naphtoquinone 
semicarbazone) protects the vascular system through an inhibitory effect on nitric oxide 
synthesis7. Many other bioactivities of semicarbazones have been reported, such as their 
antimicrobial8, pesticide9, herbicide10 and hypnotic11 properties or the ability of some of 
their Cu(II) complexes to mimic superoxide dismutase activity12. Semicarbazones are 
widely used as spectrophotometric agents for the analysis of metal ions13. Semicarbazones 
are frequently used in the qualitative organic analysis of carbonyl compounds14. 
Coordination compounds are widely used as potential drugs, in the field of catalysis and in 
biological fields. This includes a number of important biological materials such as vitamin 
B12 and haemoglobin. The chemistry of transition metal complexes of semicarbazones and 
thiosemicarbazones has been receiving considerable attention primarily because of their 
bioinorganic relevance. 
Objectives and scope of the present work 
There has been considerable interest in the studies of semicarbazones due to their 
coordination modes when bound to metals15. The wide applications and structural diversity 
of metal complexes of semicarbazones encouraged us to synthesize the tridentate ONO-
donor semicarbazones and their metal complexes. Due to good chelating ability, the present 
work is mainly concerned on the studies of two novel semicarbazones, pyruvic acid   
semicarbazone [L1] and benzaldehyde semicarbazone [L2]. The compositions of these 
semicarbazones were determined by the CHN analyses. For the characterization of these 
compounds we have used IR and UV spectral studies. We have synthesized manganese(II), 
cobalt(II), nickel(II) and copper(II)  complexes of these semicarbazones, in the ratio 1:1:1 
with metal:ligand L1:ligand L2. These complexes were characterized by various 
spectroscopic techniques, magnetic and conductivity studies, biological activities. 
Synthesis of ligand 
Benzaldehyde semicarbazone 
2 g of semicarbazide hydrochloride and 3 g of crystallized sodium acetate was dissolved in 
about in about 25-30 mL distilled water in a hard glass test tube. To this solution 1.0 g/mL of 
benzaldehyde was added and shaken well. If the mixture is turbide then 1:1 ethyl alcohol was 
added until a clear solution is obtained. Then  this reaction mixture was heated in water bath 
for 10 min. Then this solution was cooled and transfered into a beaker containing crashed ice. 
White crystals of the semicarbazone derivative were separated out from the solution. Then it 
was recrystallized from ethyl alcohol and the melting point was recorded (Scheme 1) 
Scheme 1. Benzaldehyde semicarbazone synthesis 
Pyruvic acid semicarbazone 
2 g of Semicarbazide hydrochloride and 3 g of sodium acetate was dissolved 20-30 mL 
water  in a 100 mL  beaker  then stirred  continuously  to  obtain  a clear solution of mixture  
1188                Chem Sci Trans., 2014, 3(3), 1186-1192                     
of semicarbazide  hydrochloride and sodium acetate.  The solution was filtered and placed in a 
ice bath. 2 mL of pyruvic acid was taken in a test tube and cooled it in ice bath. This ice cooled 
solution of pyruvic acid was added very slowly drop wise in an ice cooled solution of mixture of 
sodium acetate and semicarbazide hydrochloride with constant stirring. The reaction mixture 
stirred for another half an hour to separate out white precipitate of pyruvic acid semicarbazone. 
Recrystilized the crude product from hot water and the melting point was recorded (Scheme 2).  
 
Scheme 2. Pyruvic acid semicarbazone synthesis 
Synthesis of mixed ligand complexes of transition metals  
[M(L1)1(L2)1(H2O)1]Cl2 (Where L1= PASC and L2=BZSC) 
To 20 mL ethanolic solution of 0.01 M mangnese chloride a mixture of 20 mL ethanolic solution 
of 0.01 M benzaldehyde semicarbazone and 20 mL 0.01 M pyruvic acid semicarbazone ligands 
were added with continuous stirring in a water bath. Then the reaction mixture was refluxed with 
water condenser for half an hour. Then pH of the reaction mixture was raised to 7.5 to 8.00 by 
adding 5% NaOH solution drop wise with constant stirring. The pH was measured with the help 
of the pH paper. Stirring was continued for another half an hour. The coloured precipitate of the 
complex separates out from the solution. The complex was filtered and dried under IR lamp. By 
using similar procedure other complexes were prepared by mixing metal salt solutions with 
pyruvic semicarbazone and benzaldehyde semicarbazone in the ratio 1:1:1.  
Experimental analytical technique 
The compounds pyruvic acid, benzaldehyde, semicarbazide hydrochloride and chlorides of 
Cr(III), Mn(II), Co(II), Ni(II) and Cu(II) used were of analytical grade. The amount of 
metals is determined volumetrically by EDTA using double burette technique for optimum 
utilization of reagents. Indicator Erich Rome Black T was used for Mn(II) and Mg, 
ammonium thiocynate for Fe(III), xylenol orange for Co(II) and mureoxide for Ni(II) and 
Cu(II). Fast sulphone black F for calcium, carbon, hydrogen and nitrogen analysis were 
carried from SAIF, Mumbai. Specific conductance were measured at room temperature in 
DMF by a Systronics direct reading 304 conductivity meter using a glass conductivity cell 
having a cell constant L1 and L2. IR spectra of the complexes were recorded on Perkin Elmer 
FTIR instrument using KBr pellets in the region 400-4000 cm-1 from Department of Physics, 
Pratap College, Amalner .The spectral data of complexes is shown in annexure A. Electronic 
spectra of complexes were recorded on Systronics UV-Visible spectrophotometer in the 
Department of Chemistry, Pratap College, Amalner. The spectral data of complexes is 
shown in Tables 3-5. Thermogravimetric analysis was carried out on SHIMADZU STA 
6000. Antimicrobial activities are determined by using three microbial nutrients. 
Results and Discussion 
The reactions of metal chlorides with pyruvic acid semicarbazone and benzaldehyde 
semicarbazones in the 1:1:1 molar ratio results in the formation mixed ligand complexes. 
Structure of these complexes is shown in Scheme 3.  
Chem Sci Trans., 2014, 3(3), 1186-1192                1189 
N
H
N
O
H2N
COOH
+ N
N
H
H2N
O
CoCl2
HO
O
N
H
N
O
H2N
N
NH
H2N
O
CoH2O
2Cl-
EtoH
 
Scheme 3. Structure of complex 
 The resulting complexes were having different colors as given in the Table 2. They are 
insoluble in chloroform, carbon tetrachloride, methanol, ethanol but soluble in DMF. The 
elemental analyses of the complexes are given in Table 2. The conductances of the 
complexes are very low (0.1-12Ω-1 cm2 mol-1) indicating their non-electrolyte nature. 
 The TLC of the mixed ligand complexes exhibit single spots with Rf values being 
intermediate of the two corresponding symmetrical bis-complexes indicating that these are 
mixed ligand complexes rather than a mixture of two corresponding bis-complexes. From 
the magnetic moments these complexes shows octahedral geometry. 
 The conductances of the complexes are very low (0.1-12Ω-1 cm2 mol-1) indicating their 
non-electrolyte nature. In the IR spectra of the mixed ligand complexes (Table 3) the bands 
at 1544-1604 cm-1 may be assigned to the symmetric and asymmetric (C=N) vibrations. A 
strong band in the region 1748-1647 cm-1 are due to v(C=O) groups. On complex formation, 
the position of these bands is shifted toward lower side as compared to the metal free ligand. 
This indicates that the coordination takes place through the nitrogen and oxygen atom of 
the(C=N) and (C=O) groups. A broad band appears in the region at 3200-3750 cm-1 be 
attributed to the coordinated water molecule.  
 The thermograms of the compounds have been recorded in flowing nitrogen atmosphere 
at the heating rate of 10 °C/min on approximately 10 mg samples. Thermogravimetric 
analysis shows presence of one water molecules in the complexes supports the octahedral 
nature of complexes. Thermodynamic properties are shown in Table 6. 
 The electronic spectra of Cr(III) complexes (Table 5) exhibits bands in the range 
11467,22319 and 28089 cm-1 with ѵ2/ ѵ1 ratio 1.946 corresponding to 6A1g→
4T1g (
4G), 
6A1g→
4E2g  (
4G), 4A1g (
4G) and 6A1g→
4E2g (
4D),transitions, respectively suggesting 
octahedral environment around Cr(III) ion. Mn(II) complexes shows bands in the range 
12529,21296 and 27032 cm-1 assignable to 6A1g→
4T1g  (G),
 6A1g→
4T2g (G) and 
6A1g→
4A1g 
(G) transitions, respectively and magnetic moment indicates octahedral geometry. Co(II) 
complexes  shows  absorption  bands 11428,20986 and 24330 cm-1 with ѵ2/ ѵ1 ratio 1.836 
1190                 Chem Sci Trans., 2014, 3(3), 1186-1192         
corresponding to 4T1g→
4A2g (F),
 4T1g(F)→
4T1g (P) and 
4T1g(F)→
4T2g (F) transitions, 
respectively for octahedral geometry.  The electronic spectra of Ni(II) complexes exhibits 
three bands  in the range 10415,19207 and 24603 cm-1 with ѵ2/ѵ1 ratio 1.844, corresponding 
to 3A2g(F)→
3T2g(F),
 3A2g(F)→
3T1g(F) and
3A2g(F)→
3T1g(P) transitions, respectively 
suggesting octahedral geometry. The six coordinated copper complexes shows bands in the 
range 11862,18125 and  28089 cm-1 with ѵ2/ѵ1 ratio 1.5278 corresponding to 2B1g→
2A1g ,
 
2B1g →
2B2g, 
2B1g →
2E2g transitions, respectively.  
 The physical properties of ligands and complexes are given in Table 1 and 2. While IR 
spectra and analytical properties are listed in Table 3 and Table 4 respectively. Biological 
activities the compound synthesized in the present investigation have been subjected to 
various antimicrobial screening programs based on their structural features so as to ascertain 
their activity against different microorganisms. The solvent used was DMSO and the sample 
concentrations were 200, 100, 50, 25 and 12.5 ppm. The results of preliminary study on 
antimicrobial activity indicated that most of the compounds were highly and few were 
moderate active against these organisms.  
Table 1. Physical properties of ligands 
Name of the 
ligand Symbol
Colour 
and nature 
Method 
purification 
M.P. 0C
(observed) 
reported
Mol. 
Wt. 
Molecular 
formula 
Pyruvic acid 
semicarbazone
PASC 
 
White 
shining 
crystals 
Recrystallization 
from water (214) 215 145 C4H7N3O3 
Benzaldehyde  
semicarbazone BZSC 
White 
shining 
crystals 
Recrystallization 
from ethanol  (225) 224 163 C8H9N3O 
Table 2. Elemental analyses data of the complexes 
Ligand/ 
Complex 
Colour
 
Mole. 
Wt. 
%Yield of 
Compd. 
% of metal % of C % of H % of N 
 (Calculated) Found 
Cr[(PYACSC)1 
(BZSC)1] 
Green 484.49 68 (10.73)10.89 (29.73)29.40
(3.71) 
3.87 
(17.33) 
17.20 
Mn[(PYACSC)1 
(BZSC)1] 
Brown 451.99 74 (12.16)11.95 (31.85)31.30
(3.98) 
4.02 
(18.58) 
18.95 
Co[(PYACSC)1
(BZSC)1] 
Light 
pink 455.93 71 (12.93)13.60 
(31.58)
31.43
(3.94) 
4.12 
(18.42) 
18.48 
Ni[(PYACSC)1 
(BZSC)1] 
Bluish 
green 455.69 78 (12.89)12.31 
(31.60)
31.38
(3.95) 
4.04 
(18.43) 
18.25 
Cu[(PYACSC)1
(BZSC)1] 
Green 460.54 63 (13.79)13.70 (31.26)31.45
(3.90) 
4.01 
(18.23) 
18.44 
Table 3. IR spectra (cm-1) bands of the parent and mixed ligand transition metal complexes 
Ligand/
Complex
ν(OH) 
from H2O 
ν    
COOH ν(C=O) ν(C=N) 
Monosubstituted 
benzene ring 
Cr[(PYACSC)1(BZSC)1] 3750 2360 1698 1582 693 
Mn[(PYACSC)1(BZSC)1] 3697 2360 1647 1583 693 
Co[(PYACSC)1(BZSC)1] 3697 2360 1680 1540 692 
Ni[(PYACSC)1(BZSC)1] 3750 2360 1697 1547 693 
Cu[(PYACSC)1(BZSC)1] 3750 2360 1697 1587 693 
Chem Sci Trans., 2014, 3(3), 1186-1192                1191 
Table 4. Magnetic moment and molar conductance values of the complexes 
Ligand/ 
Complex 
Magnetic 
moment 
Molar 
cond.Ω1cm2mol1 at 
29 0C
Molar cond.Ω-1 cm2 mol 
at 39 0C 
Cr[(PYACSC)1(BZSC)1] 4.879 2.4 3.0 
Mn[(PYACSC)1(BZSC)1] 4.402 2.86 3.25 
Co[(PYACSC)1(BZSC)1] 4.426 5.25 6.05 
Ni[(PYACSC)1(BZSC)1] 3.90 3.6 4.4 
Cu[(PYACSC)1(BZSC)1] 2.90 3.4 4.1 
Table 5. Electronic spectra 
S.No. Name of the Complex ѵ1 ѵ2 ѵ3 B β ѵ2/ ѵ1 
1 Cr[(PYACSC)1(BZSC)1] 11467 22319 28089 766.93 0.789835 1.946 
2 Mn[(PYACSC)1(BZSC)1] 11405 25839 34129 990.627 0.961774 2.265 
3 Co[(PYACSC)1(BZSC)1] 11428 20986 24330 696.93 0.759183 1.836 
4 Ni[(PYACSC)1(BZSC)1] 10415 19207 24603 818.89 0.843347 1.8441 
5 Cu[(PYACSC)1(BZSC)1] 11862 18125 28089 885.195 0.859413 1.5278 
Table 6. Thermodynamic properties of complexes 
Ligand/ 
Complex 
Temp.0C % Mass 
LossFound 
DSC peak in
0C Endo/Exo
∆H in 
J g-1 
∆S#
 
∆E ∆ G 
 
Cr[(PYACSC)1
(BZSC)1] 
 
50-200 
200-350 
250-436.73 
9.84 
34.82 
3.698 
209.71 -444.21 -1.160 514.93 -1004.15 
Mn[(PYACSC)1
(BZSC)1] 
 
50-200 
200-300 
300-437.12 
4.485 
46.383 
11.832 
219.33 -423.47 -0.8598 554.78 -932.75 
Co[(PYACSC)1
(BZSC)1] 
 
50-150 
150-250 
250-393.29 
2.206 
8.589 
8.504 
384.39 -349.92 -0.5436 956.31 -707.28 
Ni[(PYACSC)1
(BZSC)1] 
 
50-200 
200-350 
250-437.44 
0.988 
4.883 
0.785 
212.56 -110.62 -0.2278 474.66 -221.23 
Cu[(PYACSC)1
(BZSC)1] 
 
50-150 
150-350 
350-437.25 
2.945 
43.721 
6.399 
222.82 -1380.53 -2.784 395.34 -2760.89 
Acknowledgement 
I am grateful to Principal, Pratap College, Amalner and the Head Chemistry Department 
Pratap college, Amalner for laboratory facilities. I am also thankful to the Head Physics 
Department Pratap College, Amalner for Electronic spectra and IR spectra and Head, SAIF, 
IIT Mumbai for elemental analysis. 
References 
1.  Farrell N, Coord Chem Rev., 2002, 232(1-2), 1-4; DOI:10.1016/S0010-8545(02)00100-5 
2.  West D X, Padhye S B and Sonawane P B, Structure and Bonding Springer-Verlag: 
New York, 1991, 76, 1. 
3.  Cerecetto H and Gonzalez M, Curr Topics Med Chem., 2002, 2, 1185. 
1192                               Chem Sci Trans., 2014, 3(3), 1186-1192                     
4.  Beraldo H and Gambino D, Mini Rev Med Chem., 2004, 4, 159-165. 
5.  Pandeya S N and Dimmock J R, Pharmazie, 1993, 48(9), 659-666. 
6.  Warren J D, Ronald T H and Woodward D L, J Med Chem., 1977, 20(11), 1520-
1521; DOI:10.1021/jm00221a034 
7.  Sogni P, Yang S, Pilette C, Moreau R, Gadano A, Avenard G, Bloy and Lebrec C D, 
Eur J Pharmacol., 1998, 344(1), 37-43;  DOI:10.1016/S0014-2999(97)01567-7 
8.  Singh A, Dharkarey R and Saxena G C, J Indian Chem Soc., 1996, 73, 339. 
9.  Anderson R J, Cloudsdale I S, Lamoreaux R J, Schaefer K and Harr J, US Patent 6, 
2000, 110, 869. 
10.  Copping L G, Kerry J C, Watkins T I, Wllis R J and Bryan H, US Patent 4, 1983, 
394, 387. 
11.  Pandeya S N, Aggarwal N and Jain J S, Pharmazie, 1999, 54(4), 300-302. 
12.  Patole J, Dutta S, Padhye S and Sinn E, Inorg Chim Acta, 2001, 318(1-2), 207-211; 
DOI:10.1016/S0020-1693(01)00416-9 
13.  Atalay T and Akgemci E G, Tr J Chem., 1998, 22, 123-128. 
14.  Kolb V M, Stupar J W, Janota T E and Duax  W L, J Org Chem., 1989, 54(10), 2341-
2346; DOI:10.1021/jo00271a019 
15.  Basuli F, Ruff M, Pierpont C G and Bhattacharya S, Inorg Chem., 1998, 37(23), 
6113-6116; DOI:10.1021/ic980424i 


Synthesis and Characterization of Mixed Ligand Complexes of Transition Metals with Schiff&apos;s Bases

http://citeseerx.ist.psu.edu/viewdoc/download;jsessionid=E375C6F2D4F077B7846DEFF25EE6385E?doi=10.1.1.1047.4830&rep=rep1&type=pdf

Synthesis and Characterization of Mixed Ligand Complexes of Transition Metals with Schiff's Bases

Abstract

Similar works

Full text

Available Versions

CiteSeerX

Synthesis and Characterization of Mixed Ligand Complexes of Transition Metals with Schiff&apos;s Bases

Abstract

Similar works

Full text

Available Versions

CiteSeerX

Synthesis and Characterization of Mixed Ligand Complexes of Transition Metals with Schiff's Bases