Vol.3, No.9, 783-794 (2011) Natural Science
http://dx.doi.org/10.4236/ns.2011.39103
Kinetic parameters and thermal decomposition for Novel
1,1-malonyl-bis(4-p-Chlorophenylthiosemicarbazide)
and Cu(II), Co(II), Zn(II) and Sn(II) complexes
(H4pClMaTS) synthesized by electrochemical method
Ragab R. Amin1*, Yamany B. Yamany2, Mohamed Abo-Aly3, Ali M. Hassan4
1Basic and Applied Science Department, Faculty of Dentistry, Nahda University, New Beni-Sueff, Egypt;
*Corresponding Author:
2Faculty of Medicine and Medical Science, Taif University, Taif, Saudia Arabia;
3Chemistry Department, Faculty of Science, Ain Shams University, Cairo, Egypt;
4Chemistry Department, Faculty of Science, Al-Azhar University, Cairo, Egypt.
Received 20 June 2011; revised 23 July 2011; accepted 7 August 2011.
ABSTRACT
Anodic oxidation of Co, Cu, Zn, and Sn metals in
an acetone solution of 1,1-malonayl-bis(4-p-
Chloro-phenylthiosemicarbazide) yields com-
plexes of composition with general formula
[Co2(pClMaTS)(H2O)6]·2H2O,
[Cu2(pClMaTS)(H2O)6], [Zn2(pClMaTS)(H2O)6] and
[Sn2(pClMaTS)(H2O)6]·2H2O. Chelation was inve-
stigated based on elemental analysis, conducti-
vity, magnetic moment, spectral (UV-Vis, IR,
Raman, 1HNMR, mass), thermal, and ESR stu-
dies. The Raman and infrared spectral studies
suggests the tridentate behavior of the ligand
from each tail. Since the ligand has two thiose-
micarbazide groups, it may acts in an SNO tri-
dentate fashion from each side with one of the
two metal ions forming a polynuclear complex
coordinating through both of the lone pair of
electrons the enolic oxygen of the carbonyl
group (C=O), the azomethine nitrogen (C=N) and
the thioenol form of the thiocarbonyl group
(C=S). The differential thermogravimetric analy-
sis (DTG) curves were used to study the de-
composition steps of the isolated complexes
using Horowitz-Metzger (HM) and Coats-Redfern
(CR) methods. The kinetic thermodynamic para-
meters such as: E*, ∆H*, ∆S*and ∆G* are calcu-
lated from the DTG curves.
Keywords: Metal(II) Complexes; Electrochemical;
Thermogravimetric; Bis-Thiosemicarbazide
1. INTRODUCTION
Thiosemicarbazide and their derivatives are of current
interest with respect to their uses as analytical reagents
for high performance liquid chromatographic separations
of metal(II) ions as metal chelates [1-3], potentiometric
sensors [4], analytical detrmenation of metal ions [5] and
clinical analysis [6]. Most of these compounds have an-
tifungal [7], antimicrobial [8], antitumor [9], biological
activity [10,11] as well as hypoglycemic effects [12-14].
In addition, thiosemicarbazide derivatives have ability to
form chelate complexes with transition metal ions [15-
20]. Continuing our studies for the electrochemical syn-
thesis of new metal complexes of ligands containing N,
S and O atoms through the reaction of metal ions scari-
fied from the anodic dissolution of metals [16,21,22]. In
this paper we are reported a novel complexes isolated
from the reaction between 1,1-Malonyl-bis(-4-p-chloro-
phenyl thiosemicarbazide) and the metal ions scarified
from the dissolution of Cobalt, Copper, Zinc and Tin
metals. The modern spectroscopic investigations are
used to elucidate the structure of the prepared materials.
The thermal decomposition is also used to infer the stru-
cture of the metal complexes and to calculate the diffe-
rent thermodynamic activation parameters [23,24].
2. EXPERIMENTAL
2.1. The Materials
All the chemicals (Aldrich) were subjected to purify-
cation before use. The solvents, DMF (BDH) (Analar),
absolute acetone, ethanol and methanol (Fluka) used
were reagent grade. The metals (Alfa Inorganics) used,
Co, Cu, Zn, and Sn were purchased in the form of sheets
(~2 cm × 2 cm, 2 - 3 mm thick). The oxide surface was
removed by treating the metal with conc. HNO3 for se-
veral minutes and then washing with distilled water. Tet-

R. R. Amin et al. / Natural Science 3 (2011) 783-794 784
raethylammonium perchlorate, Et4NClO4, (BDH) was
used as supplied [25].
2.2. The Organic Compounds
2.2.1. Preparation of 1,1-Malonyl-Hydrazide
1,1-Malonyl-dihydrazine was prepared by adding Ma-
lonyl Chloride (7 gm  0.05 mol) to alcoholic solution of
hydrazine hydrate (5 gm  0.1 mole). The reaction mix-
ture was exothermic and left to cool with stirring. A
brown crystal precipitate was formed and washed with
ethanol diethyl ether and left to dry. Yield (5 gm  76%)
and the melt point at 130˚C.
2.2.2. Preparation of 1,1-Malonyl
bis-4-(p-Chlorophenylthiosemi Carbazide)
1,1-Malonyl bis-4-(p-chlorophenylthiosemicarbazide)
was prepared by adding 4-chloro-phenylisothiocynate
(3.4 gm, 0.02 mol) to an alcoholic solution of malonic
acid dihydrazide (1.32 gm  0.01 mole). The reaction
mixture was refluxed for 1 hour and left to cool with
stirring. The resulting white crystals were collected and
washed with ethanol and diethyl ether, respectively. The
resulting solids were filtered hot, washed with hot dist.
water, EtOH and dried by Et2O and finally dried in
vacuo over silica gel. Yield (4.3 gm  91%) and the melt
point at 200˚C [26] (Figure 1).
2.3. Electrochemical Procedure
The apparatus used in the electrochemical reaction
consists of a tall-form 100 mL Pyrex beaker containing
50 mL of the appropriate amount of the organic ligand
dissolved in acetone solution. The cathode is a platinum
wire of approximately 1 mm diameter. In most cases, the
metal was suspended and supported on a platinum wire.
[21,22] Measurements of the electrochemical efficiency,
Ef, defined as moles of metal dissolved per Faraday of
electricity, for the M/L system (where L = ligand used)
gave Ef = 0.5  0.05 mol·F−1.[25].
Electrochemical Synthesis of 1,1-Malonayl
bis-4-(p-Chlorophenyl Thiosemicarbazide)
Metals Complexes
The ligand H4pClMaTS (0.236 gm, 0.5 mmol) was
dissolved in the minimum amount of DMSO (0.5 mL)
followed by the addition of 50 mL of acetone and 2.5 mg
of Et4NClO4. When the current 40 mA was passed
through the cell for 1hour, the amount of Cobalt con-
sumed is 59 mg and a dark brown precipitate was
formed (the product is 0.364 gm, % yield 99.7 and Ef =
0.51). It was collected, washed with diethyl ether and
dried. The resulting dark brown powder was collected
and analyzed as [Co2(pClMaTS)(H2O)6]·2(H2O). By the
same way Cu, Zn, and Sn complexes were isolated.
O
O
H
N
N
H
S
N
H
C
l
H
N
N
H
S
N
H
C
l
Figure 1. The structure of 1,1-malonayl-bis(4-p-chlorophenyl-
thio semicarbazide).
2.4. Analytical Measurements
2.4.1. Spectral Measurements
The absorbances of solutions were measured in UV/
Vis range at nano-Photoenergy Central Laboratory, Ain
Shams University. Infrared spectra for the samples were
recorded by Perkin Elmer FTIR 1605 using KBr pellets
at National Research Center, Cairo, Egypt.
2.4.2. 1H-NMR Spectra
The 1H NMR spectra were recorded on an Varian
Mercury VX-300 NMR spectrometer. All the spectra were
run at 300 MHz was run at 75.46 MHz in deuterated di-
methylsulphoxide (DMSO-d6). Chemical shifts were
quoted in δ and were related to that of the solvents.
2.4.3. Microanalytical Techniques
Carbon, hydrogen and nitrogen contents were deter-
mined using a Perkin-Elmer CHN 2400. The copper,
cobalt, zinc, and tin contents were determined gravimet-
rically by the direct ignition of the complexes at 1000˚C
for 3 hours till constant weight. The residue was then
weighted in the forms of metal oxides. The melting point
of ligand and their metal complexes were measured by
the electro thermal melting point Stuart SMP3 made in
UK.
2.4.4. Magnetic Measurements
Magnetic measurements were carried out on a Sher-
wood Scientific magnetic balance using Gouy method.
Calibratio n: Hg[Co(CNS)4] and [Ni(en)3](S2O3) are easily
prepared pure, do not decompose or absorb moisture and
pack well. Their susceptibilities at 293 K are 16.44 ×
10–6 and 11.03 × 10–6 c.g.s. Units, decreasing by 0.05 ×
10–6 and 0.04 × 10–6 per degree temperature raise respec-
tively, near room temperature. The cobalt compound, be-
sides having the higher susceptibility, also packs rather
densely and is suitable for calibrating low fields, while
the nickel compound with lower susceptibility and den-
sity is suitable for higher field. Here we were used
Hg[Co(CNS)4] only as calibrant, Micro analytical Center,
Cairo University, Egypt.
2.5. Thermal Investigation
Thermogravimetric analysis (TGA and DTG) were

R. R. Amin et al. / Natural Science 3 (2011) 783-794 785
carried out in dynamic nitrogen atmosphere (30 ml/min)
with a heating rate of 10˚C/min using a Schimadzu
TGA-50H thermal analyzer.
3. RESULTS AND DISCUSSION
Measurements of the electrochemical efficiency, Ef,
defined as moles of metal dissolved per Faraday of elec-
tricity, for the Co/L system (where L = ligand) gave Ef =
0.5  0.05 mol·F–1. The values show that the reaction of
the ligand with cobalt anode is compatible with the fol-
lowing steps 1 and 2.
1) The First step:


2
422
Cathode:H L2eH LHg

  (1)
2
22
Anode:H LCoCoH L2e
  (2)
2) The Second step:


2
22
Cathode:CoH L2eCoLHg

  (3)
2
2
Anode:CoLCoCo L2e
  (4)
Anodic oxidation of Co, Cu, Zn, and Sn metals in an
anhydrous acetone solution of 1,1-malonayl-bis (4-p-
Chlorophenylthiosemicarbazide) yields complexes of
composition with general formula
[Co2(pClMaTS)(H2O)6]2 H2O, [Cu2(pClMaTS)(H2O)6],
[Zn2(pClMaTS)(H2O)6] and
[Sn2(pClMaTS)(H2O)6]·2H 2O. Structural investigation of
the ligand and their complexes has been made based on
elemental analysis, conductivity, magnetic moment, spe-
ctral (UV-Vis, IR, Raman, 1H-NMR, Mass), thermal stu-
dies. The elemental analysis and some physical data of
the resulted compounds are given in Table 1. The com-
plexes are air-stable, hygroscopic. All 1,1-malonayl-bis
(4-p-chlorophenyl) thiosemicarbazide, Co(II), Cu(II), Zn(II)
and Sn(II) complexes are paramagnetic in nature. They
are white, dark brown, dark brown, yellowish white and
page respectively; quite stable in atmospheric conditions;
insoluble in water, ethanol and Diethylether but are
completely soluble in DMF and DMSO the complexes
have different melting points (200˚C - 243˚C).
3.1. Molar Conductivity
The molar conductivity values of the 1,1-malonayl-bis
(4-p-chlorophenylthiosemicarbazide) and its complexes
in DMSO solvent (1.0 × 10–3 mol·L–1) were 20 μs for
(H4pClMaTS) ligand, 37 μs for [Co2(pClMaTS)(H2O)6]
2(H2O), 35 μs for [Cu2(pClMaTS)(H2O) 6], 38 μs for
[Zn2(pClMaTS)(H2O)6] and 36 μs for
[Sn2(pClMaTS)(H2O)6]·2(H2O) respectively. The molar
conductivity measurements located in the range of non-
electrolytic behavior (Table 1).
3.2. Infrared Spectra
Important IR spectral data of the ligands and com-
plexes are summarized in Table 2. The IR spectrum of
[H4pClMaTS] shows bands at 3310, 3196 and 3111 cm-1
for the three-NH groups present in the ligand. The bands
occurring at 1657, 1400, 1341, 902 and 814 cm−1 are
assigned to ν(C=O), thioamide I [β(NH) + ν(CN)],
thioamide II [ν(CN) + β(NH)], ν(N-N) and ν(C=S), re-
spectively. An exhaustive comparison of the IR spectra
of the ligand and complexes gave information about the
mode of bonding of the ligand in metal complexes. The
IR spectrum of complexes [Co2(pClMaTS)(H2O)6]·2(H2O),
[Cu2(pClMaTS)(H2O)6], [Zn2(pClMaTS) (H2O) 6] and
[Sn2(pClMaTS)(H2O)6]·2(H2O) when compared with
ligand [H4pClMaTS], indicates that bands due to ν(NH),
ν(C=O) and ν(C=S) are absent, but new bands appear at
1602 and 763 cm–1 due to ν(N=C) and ν(C-S), respec-
tively. Suggesting removal of both the hydrazinic pro-
tons via enolisation and thioenolisation and bonding of
the resulting enolic oxygen and thiolato sulfur takes
place with Co (II), Cu(II), Zn(II) and Sn(II). Further-
more, the ligand bands due to thioamide I, thioamide II
and ν(N-N) undergo a positive shift of (16 - 40 cm–1),
(59 cm–1) and (23 - 43 cm–1) respectively. The magnitude
of the positive shift supports that enolic oxygen, thiolato
sulfur and both hydrazinic nitrogens are involved in co-
ordination and [H4pClMaTS] behaves as tetranegatively
charged hexadentate species in complexes
[Co2(pClMaTS)(H2O)6]2 H2O, [Cu2(pClMaTS)(H2O)6],
[Zn2(pClMaTS)(H2O)6] and
[Sn2(pClMaTS)(H2O)6].2H2O. IR spectral bands of com-
plexes are appear of bands in the range (743 - 777 cm–1)
assigned to groups (C-S) vibrations. This is also con-
firmed by the appearance of bands in the range of 418 -
428 cm–1, this has been assigned to the ν(M–N) [27,28].
And the appearance of bands in the range of 490 - 501
cm–1, this has been assigned to the ν(M-O). It is due to
the increase in the band strength, which again confirms
the coordination via the azomethine nitrogen. The band
appearing at ca. 814 cm–1 ν(C=S) and at 1657 cm–1
ν(C=O) in the IR spectral of ligand is shifted towards
lower wave number. It indicates that thione sulphur and
also the enolic oxygen coordinates to the metal ion [27].
Thus the ligand behaves as tridentate in bath saide che-
lating agent coordinating through azomethine nitrogen,
thiolate sulphur and enolic oxygen. IR spectral of ligand
and its metal complexes are shown in the Figure 2.
3.3. Raman Spectra
Important Raman spectral data of the ligands and its
metal complexes are summarized in Table 3. The Raman
spectrum of [H4pClMaTS] shows bands at 3201 cm–1 for

R. R. Amin et al. / Natural Science 3 (2011) 783-794 786
Table 1. Analytical Results for the Prepared Complexes of 1,1-malonayl-bis(4-p-chlorophenyl thiosemicarbazide) and their metal
complexes.
% Found (Calc.)
Compound
Empirical formula Formula weight Colour m.p. (˚C) C H N
Am
μs
(H4pClMaTS), I
C17H16Cl2N6O2S2
471.38 White 200 43.18 (43.32)3.08 (3.42) 17.6 (17.83)20
[Co2(pClMaTS)(H2O)6]·2(H2O), Ia
C17H28Cl2Co2N6O10S2 729.3 Dark Brown 220 27.7 (28) 4.25 (3.87) 11.35 (11.52)37
[Cu2(pClMaTS)( H2O)6], Ib
C17H24Cl2Cu2N6O8S2 702.54 Dark brown 210 29.86 (29.06)3.39 (3.44) 11.5 (11.96)35
[Zn2(pClMaTS)(H2O)6], Ic
C17H24Cl2Zn2 N6O8S2
706.3 Yellowish White213 29.07 (28.91)3.30 (3.43) 11.40 (11.9)38
[Sn2(pClMaTS) (H2O)6]·2(H2O), Id
C17H28Cl2Sn2 N6O10S2
848.9 Page 243 24.01 (24.05)3.22 (3.32) 9.34 (9.9) 36
Table 2. Significant IR spectral bands (cm−1) of the ligand of 1,1-malonay l-bis(4-p-chlorophenyl thiosemicarbazide) and its metal
complexes.
The compound
Assignments I Ia Ib Ic Id
υ(OH) - 3407 3435 3429 3429
υ(N4H) 3310 3237 3238 3305 3305
υ(N2H) 3196 3179 3180 3194 3197
υ(NH) 3111 3109 3111 3105 3111
CH-arom. 3005 3034 3053 3005 3007
CH-aliph. 2940 2980 2934 2938 2940
υ(C=O)/υ(NCO) 1657 1595 1599 1591 1599
Thioamide I
[β(NH)+υ(CN)] 1400 1420 1431 1416 1440
Thioamide II
[υ(CN)+β(NH)] 1341 1400 1400 1400 1400
δ(OH) - 1306 1310 1310 1308
υ(C-O) - 1290 1219 1273 1246
υ(N-N) 902 935 945 924 925
υ(C=S)/υ(C-S) 814 743 772 777 777
υ(M-O) - 493 501 490 490
υ(M-N) - 421 428 418 421
Table 3. Significant Raman spectral bands (cm−1) of the ligand of 1,1-malonayl-bis(4-p-chlorophenyl thiosemicarbazide) and it’s
metal complexes.
The compound
Assignments I Ic
υ(NH) 3201 3209
CH-arom. 3063 3062
CH-aliph. 2934 2933
υ(C=O)/υ(NCO) 1635 1593
Thioamide I [β(NH)+υ(CN)] 1405 1444
Thioamide II [υ(CN)+β(NH)] 1355 1395
δ(OH) - 1315
υ(N-N) 1088 1090
υ(C=S)/υ(C-S) 824 779

R. R. Amin et al. / Natural Science 3 (2011) 783-794 787
Figure 2. IR spectral of 1,1-Malonayl-bis(4-p-chloro phenyl-
thiosemicarbazide) and its metal complexes.
the NH groups present in the ligand. The bands occur-
ring at 1635, 1405, 1355, 1088 and 824 cm–1 are as-
signed to ν(C=O), thioamide I [β(NH) + ν(CN)], thioa-
mide II [ν(CN) + β(NH)], ν(N-N) and ν(C=S), respec-
tively [29]. An exhaustive comparison of the Raman
spectra of the ligand and complexes gave information
about the mode of bonding of the ligand in metal com-
plexes. The Raman spectrum of complexes
[Zn2(pClMaTS)(H2O)6]) when compared with
[H4pClMaTS], indicates that bands due to ν(NH), ν(C=O)
and ν(C=S) are absent, but new bands appear at ca. 1593
and 779 cm–1 due to ν(N=C) and ν(C-S), respectively.
suggesting removal of both the hydrazinic protons via
enolisation and thioenolisation and bonding of the result-
ing enolic oxygen and thiolato sulfur takes place with
Zn(II). Furthermore, the ligand bands due to thioamide I,
thioamide II and ν(N-N) undergo a positive shift of (39
cm–1), (40 cm–1) and (2 cm–1) respectively. The magni-
tude of the positive shift supports that enolic oxygen,
thiolato sulfur and both hydrazinic nitrogens are in-
volved in coordination and [H4pClMaTS] behaves as
tetranegatively charged hexadentate species in com-
plexes [Zn2(pClMaTS)(H2O)6]. Raman spectral bands of
complexes are appear of bands at (779 cm–1) assigned to
groups (C-S) vibrations. It indicates that thione sulphur
and also the enolic oxygen coordinates to the metal ion
[30]. Thus, it may be concluded that the ligand behaves
as hexadentate chelating agent coordinating through azo-
methine nitrogen and thiolate sulphur.
3.4. Electronic Spectra
The electronic spectra of both 1,1-malonayl-bis(4-p-
chlorophenyl thiosemicarbazide) ligand and its com-
plexes were performed in DMSO and the spectral data
are listed in Table 4. There are two main absorption
bands in the spectra of the free ligand and their com-
plexes; the first band is exhibited at the range 284 - 308
nm and assigned to π-π* [31], and the second appeared at
the range 330 - 358 nm due to n-π* intraligand transi-
tions [32]. These absorptions also present in the spectra
of the Co(II), Cu(II) , Zn(II) and Sn(II) and [H4pClMaTS]
ligand complexes, but they are shifted. In the spectra of
all complexes attributed to the complexation behavior of
the ligand towards metal ions which was supported the
coordination of the ligand-to-metallic ions, shown as the
Figure 3.
3.5. Magnetic Susceptibility
Co(II) has the electronic configuration 3d* and should
exhibit a magnetic moment higher than that expected for
two unpaired electrons in octahedral (1 - 1.13 BM). The
magnetic moment observed for the Co(II) complexes lies
in the value of 1.3 BM which is consistent with the octa-
hedral stereochemistry of the complexes. Room-tempe-
rature magnetic moment of the Cu(II) complexes lies in
the range of 1 BM, corresponding to one unpaired elec-
tron. whatsoever the geometry of Cu(II) is, its complexes
always show magnetic moment corresponding to one
unpaired electron.
3.6. 1H-NMR Spectra
Thus, the 1H-NMR spectra of the
[Zn2(pClMaTS)(H2O)6] complex on comparing with
those of spectrum of the free 1,1-malonayl-bis(4-p-
chlorophenylthiosemicarbazide) ligand (L) indicate that.
L ligand act as hexadentate ligand through the nitrogen
atom of C=N azomethine group, oxygen atom of C=O
carbonyl group and sulfur atom of C=S group. 1H-NMR
spectra of zinc(II) complex was carried out in DMSO-d6
as a solvent, the data obtained are in agreement with the
suggested coordination through the C=N and C=S groups
by presence of the signals of NH, the complexes formed
due to loss four protons (two from 2NH amine groups
and two protons from 2NH amide groups).
(H4pClO × TS) 1H-NMR δ (ppm): 9.75(6,18NH amide
group), 1.95(7,19NH amine group), 3.35(CH2) 6.6 - 7.75
(CH-aromatic)
[Zn2(pClO × TS)(ac)2] 2(H2O) 1H-NMR δ (ppm): 1.15
(H2O), (NH amide groups disappeared), (NH amine groups
disappeared), 3.35(CH2), 5.2(10,22CNH aromatic), 6.6 -
7.75(CH-aromatic shifted).

R. R. Amin et al. / Natural Science 3 (2011) 783-794 788
Table 4. The electronic spectral data of1,1-malonayl-bis(4-p-chlorophen ylthiosemicarbazide) and its metal complexes.
λmax nm (cm−1)
Compound
π-π* C=S n-π* C=S CT-transition
H4pClMaTS 287 (34840) 344 (29070)
[Co2(pClMaTS)(H2O)6]·2(H2O) 288 (34720) 342 (29240) 462 (21650) 485 (20620) 522 (19160)
[Cu2(pClMaTS)(H2O)6] 308 (32470) 358 (27930) 466 (21460) 493 (20280) 524 (19080)
[Zn2(pClMaTS)(H2O)6] 284 (35210) 344 (29070)
[Sn2 (pClMaTS) (H2O)6]·2(H2O) 288 (34720) 330 (30300)
Figure 3. The electronic spectral of 1,1-malonayl-bis(4-p-chloro phenylthio-
semicarbazide) and its metal complexes.
3.7. Mass Spectrum
The electronic impact mass spectrum of the complex
[Cu2(pClMaTS)(H2O)6]{1,-malonayl-bis(4-p-chlorophen
ylthiosemicarbazide) copper trihydrate} is fragment to
half molecule species at m/z = 304 amu corresponding to
species {4-methylene-p-chlorophenylthiosemicarbazide
copper} [C9H7ClN3OSCu], which confirms the proposed
formula. It also shows series of peaks at 36, 50, 75, 90,
111, 138, 152, 184, 229, 263, and 300 amu correspond-
ing to various fragments. The electronic impact mass
spectrum of the [Sn2(pClMaTS)(H2O)6]·2(H2O) complex
shows fragment molecular ion (M+) peak at m/z = 421
amu corresponding to species [C10H9ClN3O4SSn], which
confirms the proposed formula. It also shows series of
peaks at 75, 111, 127, 169, 218, 302 and 336 amu corre-
sponding to various fragments. The intensities of these
peaks give the idea of the stabilities of the fragments.
3.8. Thermogravimetric Analysis
Thermogravimetric analysis curves (TGA and DTG)
of the 1,1-malonayl-bis-(4-p-chlorophenyl thiosemicar-
bazide) ligand and its complexes are shown in Figure 4
and all the data are summarized in Table 5. 1,1-
Malonayl-bis-(4-p-chlorophenylthiosemicarbazide) ligand
was thermally decomposed in mainly decomposition
steps within the temperature range successive decompo-
sition steps within the temperature range 25˚C - 700˚C.
The first decomposition step (obs. = 39.14%, calc. =
39%) within the temperature range 25˚C - 245˚C, may be
attributed to the liberation of the 2(HNCO), 2H2S and
2(NH) fragments. The second decomposition steps found
within the temperature range 245˚C - 345˚C (obs. =
32.8%, calc. = 32.5%), which is reasonably accounted by
the removal of 2(HCN), (C2H2) and Cl2. The decom-
position of the ligand molecule ended with a final (C17H2)
residue (obs. = 28%, calc = 28.3%).
The complex [Co2(pClMaTS)(H2O)6]2(H2O) was ther-
mally decomposed in five successive decomposition
steps within the temperature range 25˚C - 1000˚C. The
first decomposition step (obs. = 5.2%, calc. = 4.94%)
within the temperature range 25˚C - 188˚C, may be attri-

R. R. Amin et al. / Natural Science 3 (2011) 783-794 789
Figure 4. TGA and DrTGA diagram of 1,1-malonayl-bis(4-p-chlorophenylthiosemicarbazide) and its metal complexes.
buted to the liberation of the two water molecules. The
second decomposition steps found within the tempera-
ture range 188˚C - 448˚C (obs. = 33.1%, calc. = 33.5%),
which is reasonably accounted by the removal of 6water
molecules 2N2, 2(HCN), and C2H2 fragments. The de-
composition third step found within the temperature
448˚C - 760˚C (obs. = 23.4%, calc = 22.9%) which is
reasonably accounted for by the removal of S2, Cl2 and
O2 molecules. The decomposition fourth step found
within the temperature 760˚C - 885˚C (obs. = 21.8%,
calc = 22.5%) which is reasonably accounted for by the
removal of CH4 and C12H4 fragments. The rest of the
ligand molecule was removed and fifth the decomposi-
tion of the Co(II) complex molecule ended with a final
Co2 molecule is cobalt residue (obs. = 17.3%, calc =
16.5%).
The TG curve of [Cu2(pClMaTS)(H2O)6] complex in-
dicates that the mass change begins at 25˚C and con-
tinuous up to 1000˚C. The first and second mass loss
corresponds to the liberation of the 6water molecules
(obs. = 16.4%, calc = 15.4%) within the temperature
range 25˚C - 245˚C. The third decomposition step occurs
in the range 245˚C - 475˚C and corresponds to the loss of
N2, 2(HCN), N2H2, and O2 (obs. = 20.6%, calc = 20.5%).
The decomposition fourth step found within the tem-
perature 475˚C - 765˚C (obs. = 42.4%, calc = 42.5%)
which is reasonably accounted for by the removal of
(C13H8, S2 and Cl2) fragments. The fifth decomposition

R. R. Amin et al. / Natural Science 3 (2011) 783-794 790
Table 5. The thermal data of 1,1-Malonayl-bis(4-p-chlorophenyl thiose micarbazide) and their metal complexes.
TG weight loss (%)
Compound Steps Temperature ring (˚C) Calc. Found Assignments Tmax ˚C
1 25 - 245 39 39.1 2(HNCO), 2H2S and 2(NH) fragments
2 245 - 345 32.5 32.8 2(HCN), (C2H2) and Cl2
I
3 More than 345 26.8 27.5 (C17H2) residual
212
278
524
1 25 - 188 4.94 5.2 2water
2 188 - 448 33.5 33.1 6water molecules, 2N2, 2(HCN), and C2H
2
fragments
3 448 - 760 22.9 23.4 S2, Cl2 and O2 molecules
4 760 - 885 22.5 21.8 CH4 and C12H4 fragments
Ia
5 More than 885 16.5 17.3 Co2 molecule is cobalt residue
242
477
854
959
1,2 25 - 245 15.4 16.4 6water
3 245 - 475 20.5 20.6 N2, 2(HCN), N2H2, and O2
4 475 - 765 42.5 42.4 C13H8, S2 and Cl2 fragments
Ib
5 More than 765 21.5 20.6 C2 and Cu2 metal residual
181
277
506
680
974
1 25 - 224 15.3 15.5 6water molecules
2 224 - 338 26.9 26.5 2N2, S2, 1/2O2 and 2(HCN) fragment
3 338 - 643 18.2 18.6 1/2O2, Cl2, CH4 and C2H2 molecules
Ic
4 More than 643 39.5 39.4 residue metal of Zn2 and C12H4 fragment
219
309
1, 2 25 - 321.7 25.2 24.7 8 water and HNCO and HCN molecules
3 321.7 - 505.6 8.8 9.3 1/2S2 and HNCO
4 505.6 - 589 9.1 9.56 NH3, N2 and 1/2S2 molecules
Id
5 More than 589 56.8 56.44 Cl2, C14H6 and Sn2 the residual metal
229
301
518
steps are final decomposition organic ligand to the C2
and Cu2 metal residual. (obs. = 20.6%, calc = 21.5%).
The complex [Zn2(pClMaTS)(H2O)6] was thermally
decomposed in mainly four decomposition steps within
the temperature range 25˚C - 700˚C. The first decompo-
sition step (obs. = 15.5%, calc = 15.3%) within the tem-
perature range 25˚C - 224˚C, may be attributed to the
liberation of 6water molecules. The decomposition se-
cond step found within the temperature 224˚C - 338˚C
(obs. = 26.5%, calc = 26.9%) which is reasonably ac-
counted for by the removal of 2N2, S2, 1/2O2 and 2(HCN)
fragment. The decomposition third step found within the
temperature 338˚C - 643˚C (obs. = 18.6%, calc = 18.2%)
which is reasonably accounted for by the removal of
1/2O2, Cl2, CH4 and C2H2 molecules. The rest of the
ligand molecule was removed and fourth the decom-
position of the ligand molecule ended with a final residue
metal of Zn2 and C12H4 fragment (obs. = 39.4%, calc =
39.5%).
[Sn2(pClMaTS) (H2O)6]·2(H 2O) the complex is ther-
mally stable up to 50˚C and decomposition beyond this
temperature as indicated by the first and second loss
steps in the TG curve. First and second step, the mass
loss at 321.7˚C corresponds to the loss of 8 water and
HNCO and HCN molecules (obs. = 24.7%, calc =
25.2%). Continuous mass loss in the TG curve from
321.7˚C to 503.6˚C corresponds to the loss of 1/2S2 and
HNCO molecules (obs. = 9.3%, calc = 8.8%). The rest of
organic moiety NH3, N2 and 1/2S2 molecules was re-
moved on the fourth step within the temperature range
503.6˚C - 589˚C (obs. = 9.56%, calc = 9.1%). The final
decomposition of the Cl2, C14H6 and Sn2 the residual
metal (obs. = 56.44%, calc = 56.8%).
3.9. Kinetic Studies
The thermodynamic activation parameters of decom-
position processes of hydrated Co(II), Cu(II), Zn(II) and
Sn(II) complexes, namely activation energy (E∗), en-
thalpy (ΔH∗), entropy (ΔS∗), and Gibbs free energy
change of the decomposition (ΔG∗), were evaluated
graphically (Figure 5) by employing the Coats-Redfern
and Horowitz-Metzger relations.
ΔH* = E* – RT
ΔG* = ΔH* – TΔS*
The data are summarized in Table 6. The activation
energies of decomposition were in the range 56.9 - 461
kJ·mol–1. The high values of the activation energy illus-

R. R. Amin et al. / Natural Science 3 (2011) 783-794 791
Figure 5. Kinetic data curves of: (a) 1,1-Malonayl-bis(4-p-chlorophenyl thiosemicarbazide(H4pClMaTS), (b) Co(II), (c) Cu(II),
(d) Zn(II) and (e) Sn(II) complexes.

R. R. Amin et al. / Natural Science 3 (2011) 783-794 792
Table 6. Kinetic parameters using the Coats-Redfern (CR) and Horowitz-Metzger (HM) operated for 1,1-malonayl-bis(4-p-Chloro-
phenylthiosemicarbazide) (H4pClMaTS) and its Co(II), Cu(II), Zn(II) and Sn(II) complexes.
Parameter
Compound Stage Method
E (J·mol−1)A (s−1) ΔS (J·mol −1·K−1)ΔH (J·mol−1) ΔG (J·mol−1)
R
CR 1.79 × 105 1.94 × 1017 8.20 × 101 1.75 × 105 1.35 × 105 0.9997
HM 1.54 × 105 7.15 × 1014 3.54 × 101 1.50 × 105 1.33 × 105 0.9992 I 1st
Average 1.66 × 105 9.74 × 1016 5.87 × 101 1.62 × 105 1.34 × 105 0.9995
CR 4.70 × 104 1.40 × 102 –2.08 × 102 4.27 × 104 1.50 × 105 0.9963
HM 6.65 × 104 4.13 × 104 –1.61 × 102 6.22 × 104 1.45 × 105 0.9956 Ia 1st
Average 5.67 × 104 2.07 × 104 –1.85 × 102 5.25 × 104 1.48 × 105 0.9960
CR 6.07 × 104 2.32 × 103 –1.86 × 102 5.61 × 104 1.58 × 105 0.9931
HM 6.87 × 104 2.35 × 104 –1.66 × 102 6.42 × 104 1.55 × 105 0.9918 Ib 1st
Average 6.47 × 104 1.29 × 104 –1.76 × 102 6.02 × 104 1. 57 × 105 0.9925
CR 4.58 × 104 1.17 × 1047 6.52 × 102 4.54 × 105 1.33 × 105 0.9977
HM 4.65 × 105 1.20 × 1048 6.70 × 102 4.61 × 105 1.30 × 105 0.9982 Ic 1st
Average 4.61 × 105 6.57 × 1047 6.62 × 102 4.57 × 105 1.32 × 105 0.9980
CR 2.76 × 1041.68 × 1027 2.72 × 102 2.72 × 105 1.36 × 105 0.9950
HM 2.95 × 1051.77 × 1029 3.11 × 102 2.90 × 105 1. 35 × 105 0.9945 Id 1st
Average 2.85 × 105 8.94 × 1028 2.91 × 102 2.81 × 105 1.35 × 105 0.9948
Figure 6. The suggested Octahedral structure of 1,1-malonayl-bis (4-p-chloro-
phenylthiosemicarbazide) Metal trihydrate Complex. M = Co(II), Cu(II), Zn(II)
and Sn(II).
trated to the thermal stability of the complexes. ΔG is
positive for reaction for which ΔH is positive and ΔS is
negative. The reaction for which ΔG is positive and ΔS is
negative considered as unfavorable or non spontane- ous
reactions. Reactions are classified as either exother- mic
(ΔH < 0) or endothermic (ΔH > 0) on the basis of
whether they give off or absorb heat. Reactions can also
be classified as exergonic (ΔG < 0) or endergonic (ΔG >
0) on the basis of whether the free energy of the system
decreases or increases during the reaction. The thermo-
dynamic data obtained with the two methods are in har-
mony with each other. The activation energy of All
1,1-Malonayl-bis(4-p-Chlorophenyl) thiosemicarbazide
and its Co+2, Cu+2, Zn+2 and Sn+2 complexes is expected
to increase in relation with decrease in their radii (Tunali
and Ozkar 1993). The smaller size of the ions permits a
closer approach of the ligand (H4pClMaTS). Hence, the
E value in the first stage for the Zn+2 complex is higher
than that for the other Sn+2, Cu+2 and Co+2 complex. The
correlation coefficients of the Arrhenius plots of the ther-
mal decomposition steps were found to lie in the range
0.9925 to 0.9995 showing a good fit with linear function.
It is clear that the thermal decomposition process of all
(H4pClMaTS) complexes is non-spontaneous, i.e., the

R. R. Amin et al. / Natural Science 3 (2011) 783-794 793
complexes are thermally stable.
4. CONCLUSIONS
We can concluded from the above discussions on the
(H4pClMaTS) ligand and its Co(II), Cu(II), Zn(II) and
Sn(II) complexes using the elemental analysis, molar
conductivity, IR, Raman, UV, 1HNMR, mass spectra and
magnetic properties, as well as TG/DTG, that. Thus the
ligand behaves as tridentate in bath saide chelating agent
coordinating through azomethine nitrogen, thiolate sul-
phur and enolic oxygen as shown in Figure 6.
REFERENCES
[1] Zhao, Y. (2000) Liquid chromatographic determination of
chelates of cobalt(II), copper(II) and iron(II) with 2-
thiophe-necarboxald-hyde-4-phenyl-3-thiosemicarbazone.
Chromatographia, 51, 231-234.
doi:10.1007/BF02490570
[2] Khuhawar, M.Y. and Lanjwani, S.N. (1998) Liquid
chromatographic determination of cobalt(II), copper(II)
and iron(II) using 2-thiophenaldehyde-4-phenyl-3-thiosemi-
carbazone as derivatizing reagent. Talanta, 46, 485-490.
doi:10.1016/S0039-9140(97)00213-0
[3] Lunn, G., Phillips, L.R. and Pacula-Cox, C. (1998) Re-
versed phase high performance liquid chromatography of
4-(2-pyridyl)-1-piperazinethio-carboxylic acid 2-[1-(pyridyl)
ethylidene] hydrazide dihydrochloride, a synthetic thio-
semicarbazone with anti-tumour activity. Journal of
Chromatography B: Biomedical Sciences and Applica-
tions, 708, 217-222. doi:10.1016/S0378-4347(97)00637-3
[4] Hoshi, S., Higashihara, K., Suzuki, M., Sakurada, Y.,
Sugawara, K., Uto, M. and Akatsuka, K. (1997) Simulta-
neous determination of platinum(II) and palladium(II) by
reversed phase high-performance liquid chromatography
with spectrophotometric detection after collection on and
elu-tion from resin coated with dimethylglyoxal bis-(4-
phenyl-3-thiosemicarbazone). Talanta, 44, 571-576.
doi:10.1016/S0039-9140(96)02064-4
[5] Gismera, M.J., Mendiola, M.A., Procopio, J.R. and
Sevilla, M.T. (1999) Copper potentiometric sensors based
on copper complexes containing thiohydrazone and thio-
semicar-bazone ligands. Analytica Chimica Acta, 385,
143-149. doi:10.1016/S0003-2670(98)00840-X
[6] Qu, J.Y., Liu, M. and Liu, K.Z. (1999) Simultaneous de-
termination of lead and copper by carbon paste electrodes
modified with pyruvaldehyde bis (NN’-dibutyl thiosemi-
carbazone). Analytical Letters, 32, 1991-2006.
[7] West, D.X., Carlson, C.S., Liberta, A.E. and Scovil, J.P.
(1990) The chemical and antifungal properties of the
Copper (II) complexes of 2-acetyl-pyrazine 4N-methyl-,
4N-di-methyl-, and 3-hexamethyleneiminyl-thio-semicarba-
zone. Transition Metal Chemistry, 15, 383-387.
doi:10.1007/BF01177467
[8] West, D.X., Carlson, C.S., Liberta, A.E., Albert, J.N. and
Daniel, C.R. (1990) Transtion metal ion complexes of
thiosemicarba-zones derived from 2-Acetylpyridine. Tran-
sition Metal Chemistry, 15, 341-344.
doi:10.1007/BF01177458
[9] Chohan, Z.H. (2009) Metal-based antibacterial and anti-
fun-gal sulfonamides: Synthesis, characterization, and bio-
logical properties. Transition Metal Chemistry, 34, 153-
161. doi:10.1007/s11243-008-9171-y
[10] Liu, M.C., Lin, T.S., Penketh, P. and Sartorelli, A.C.
(1995) Synthesis and antitumor activity of 4- and
5-substituted de-rivatives of isoquinoline-1-carboxalde-
hyde thiosmicar-bazone. Journal of Medicinal Chemistry,
38, 4234-4243. doi:10.1021/jm00021a012
[11] Liu, M.C., Lin, T.S., Cory, J.G., Cory, A.H. and Sartorelli,
A.C. (1996) Synthesis and biological Activity of 3- and
5-amino derivatives of pyridine-2-carboxaldehyde thio-
semicar-bazone. Journal of Medicinal Chemistry, 39,
2586-2593. doi:10.1021/jm9600454
[12] Zhu, X., Wang, C., Lu, Z. and Dang, Y. (1997) Synthesis,
charac-terization and biological activity of the Schiffbase
derived from 3,4-dihydroxybenz-aldehyde and thiosemi-
carbazide and its metal complexes with Nickel(II) and
Iron(II). Transition Metal Chemistry, 22, 9-13.
doi:10.1023/A:1018453316348
[13] Lim, J.K., Mathias, C.J. and Green, A.M. (1997) Mixed-
bis(thiosemi-carbazone) ligands for the preparation of
copper radiopharmaceuticals: Synthesis and evaluation of
tetradentate ligands containing two dissimilar thiosemi-
carbazone functions. Journal of Medicinal Chemistry, 40,
132-136. doi:10.1021/jm9605703
[14] Sathisha, M.P., Budagumpi, S., Kulkarni, N.V., Kurdekar,
G.S., Revankar, V.K. and Pai, K.S.R. (2010) Synthesis,
structure, electro-chemistry and spectral characterization
of (d-glucopyra-nose)-4-phenylthiosemicarbazide metal
complexes and their antitumor activity against Ehrlich
Ascites Carcinoma in Swiss albino mice. European Jour-
nal of Medicinal Chemistry, 45, 106-113.
doi:10.1016/j.ejmech.2009.09.031
[15] Mostafa, M.M. (2007) Spectroscopic studies of some
thio-semicarbazide compounds derived from Girard’s T
and P. Spectrochimica Acta Part A: Molecular and Bio-
molecular Spectroscopy, 66, 480-486.
doi:10.1016/j.saa.2006.02.063
[16] El-Shekeil, A., Al-Yusufy, F., Amin, R.R. and Abdullah, A.
(2004) The DC Electrical Conductivity of the Direct
Electro-chemically Synthesized Poly (azome-thine-thio-
semicarb-zone)-metal complexes. Journal of Inorganic
and Organometallic Polymers, 14, 131-148.
doi:10.1023/B:JOIP.0000028091.50660.3a
[17] Sladjana, B., Novaković, G.A. and Bogdanović, L.V.M.
(2005) Transition metal complexes with thiosemicarba-
zide-based ligands and the supramolecular arrangement
in the Ni(II) complexes of S-methy-lisothiosemicarbazide.
Inorganic Chemistry Communications, 8, 9-13.
doi:10.1016/j.inoche.2004.10.001
[18] Vukadin, M.L., Slađana, B.N., Bogdanović, G.A., Jokso-
vić, M.D. and Mészáros, K. (2007) Transition metal
complexes with thio-semicarbazide-based ligands. Part
LVI: Nickel(II) complex with 1,3-diphenylpyrazole-4-
carboxaldehyde thiosemicarbazone and unusually defor-
med coordination geometry. Polyhedron, 26, 3783-3792.
doi:10.1016/j.poly.2007.04.012
[19] El-Asmy, A.A., Al-Ansi, T.Y., Amin, R.R., El-Shahat,
M.F., Structural studies on cadmium(II), Co(II), Cu(II)
Ni(II) and Zn(II) complexes of 1-malonyl bis(4-phenyl-
thiosemi-carbazide. Transition Metal Chemistry, 15, 12-

R. R. Amin et al. / Natural Science 3 (2011) 783-794 794
15.
[20] El-Asmy, A.A., Al-Ansi, T.Y., Amin, R.R. and Mounir, M.
(1990) Spectral, magnetic and electrical properties of
1-succinyl bis (4-phenylthiosemicarbazide) complexes.
Polyhedron, 9, 2029-2034.
doi:10.1016/S0277-5387(00)84032-2
[21] Amin, R.R. (2010) Chemical and electrochemical prepa-
ration for Co(II) complexes of some pyri-dine-2-(1H)-
thione-3-cyano-4-(2-methylphenyl)-5,6-ring fused cycloal-
kane derivatives. Journal of Phos-Phorus, Sulfur, and
Silicon and the Related Elements, 185, 537-543.
doi:10.1080/10426500902840861
[22] Amin, R.R. and El-Gemeie, G.E.H. (2001) The direct
electro-chemical synthesis of Co(II), Ni(II) and Cu(II)
com-plexes of some pyridinethione derivatives. Synthesis
Reactivity Inorganic and Nanometal-Organic Chemistry,
31, 431-440. doi:10.1081/SIM-100002230
[23] Refat, M.S., El-Deen, I.M., Amin, R.R. and El-Ghol, S.
(2010) Spectroscopic studies and biological evaluation of
some transition metal complexes of a novel schiff base li-
gands derived from 5-arylazo-salicyladehyde and o-amino
phenol. Toxicological & Environmental Chemistry, 92,
1093-1110. doi:10.1080/02772240903252173
[24] Refat, M.S., El-Deen, I.M., Anwer, Z.M. and El-Ghol, S.
(2009) Bivalent transition metal complexes of cou-
marin-3-ylthio-semicarbazone derivatives: Spectroscopic,
antibacterial activity and thermogravimetric studies.
Journal of Molecular Structure, 920, 149-162.
doi:10.1016/j.molstruc.2008.10.059
[25] Rajesh, K. and Dennis, G.T. (1989) The direct electro-
chemical synthesis of metal complexes of 2,2’-dipyridy-
lamine. Inorganica Chimica Acta, 157, 51-56.
[26] Furniss, B.S., Hannaford, A.J., Smith, P.W.G. and Tatchell,
A.R. (1991) Vogel’s textbook of practical organic chemi-
stry. Longman Scientific and Technical, John Wiely &
Sons, Inc., New York.
[27] El-Metwally, N.M., El-Shazly, R.M., Gabr, I.M. and
El-Asmy, A.A. (2005) Physical and spectroscopic studies
on novel vanadyl complexes of some substituted thio-
semi-carbazides. Spectrochimica Acta Part A: Molecular
and Biomolecular Spectroscopy, 61, 1113-1119.
doi:10.1016/j.saa.2004.06.027
[28] El-Asmy, A.A., Al-Gammal, O.A., Dena, A.S. and Ghazy,
S.E. (2009) Synthesis, characterization, molecular mod-
eling and eukaryotic DNA degradation of 1-(3,4-dihydro-
xybenzylidene) thiosemicarbazide com-plexes. Journal of
Molecular Structure, 934, 9-22.
doi:10.1016/j.molstruc.2009.05.039
[29] Refat, M.S. and Killa, H.M.A. (2010) Hammad fetooh,
spectro-scopic and thermal characterization of Cu(II),
Co(II), Ni(II) and Mn(II) complexes of fluorescent dye
4-N,N-dimethyl-ethanolamine-N-allyl-1,8-naphthalimide
(4DMEAN). Journal of Molecular Structure, 983, 122-
132. doi:10.1016/j.molstruc.2010.08.041
[30] Chandra, S. and Kumar, U. (2005) Spectral and magnetic
studies on manganese(II), cobalt(II) and nickel(II) com-
plexes with Schiff bases. Spectrochimica Acta A, 61,
219-24. doi:10.1016/j.saa.2004.03.036
[31] Hassaneien, M.M., Gabr, I.M., Abdel-Rhman, M.H. and
El-Asmy, A.A. (2008) Synthesis and structural investiga-
tion of mono- and polynuclear copper complexes of
4-ethyl-1-(pyridin-2-yl) thiosemicarbazide. Spectrochimica
Acta Part A, 71, 73-79. doi:10.1016/j.saa.2007.11.009
[32] Lever, A.B.P. (1988) Inorganic electronic spectroscopy.
Elsevier Publishing Company, Amsterdam, 318-361.