Spectroscopic, thermogravimetric and antibacterial studies for some bivalent metal complexes of oxalyl-, malonyl- and succinyl-bis(4-p- chlorophenylthiosemicarbazide)

Article abstract of DOI:10.1016/j.molstruc.2011.11.024

Anodic oxidation of Co, Cu, Zn, and Sn metals in an anhydrous acetone solution of 1,1-oxalyl-, malonyl- or succinyl-bis(4-p- chlorophenylthiosemicarbazide) yields a new polynuclear complexes. The isolated complexes have the general composition [M₂(L)(H₂O) ₆], L = pClSuTS and M = Co(II), Cu(II) or Sn(II), [M ₂(L)(H₂O)_n]·nH₂O where M = Cu(II), Co(II) or Sn(II), L = pClOxTS and n = 2 or 6, and [M₂(L)(ac) ₂]·nH₂O where M = Co(II) or Zn(II), L = pClOxTS or pClSuTS and n = 2. The thermogravimetry (TG) and derivative thermogravimetry (DTG) have been used to study the thermal decomposition of the investigated bisthiosemicarbazide ligands and their metal complexes. The kinetic thermodynamic parameters such as: E, ΔH, ΔS and ΔG are calculated using Horowitz-Metzger (HM) and Coats-Redfern (CR) equations. The kinetic thermodynamic parameters such as: E, ΔH, ΔSand ΔG are calculated from the DTG curves. The tested compounds show a reasonable activity against four strains of Gram-negative bacteria; Escherichia coli, Pseudomonas aeruginosa species and Gram-positive bacteria; Bacillus cereus and Staphylococcus aureus.

Full text of DOI:10.1016/j.molstruc.2011.11.024

Journal of Molecular Structure 1008 (2012) 54–62
Contents lists available at SciVerse ScienceDirect
Journal of Molecular Structure
journal homepage: www.elsevier.com/locate/molstruc
Spectroscopic, thermogravimetric and antibacterial studies
for some bivalent metal complexes of oxalyl-, malonyl- and
succinyl-bis(4-p-chlorophenylthiosemicarbazide)
Ragab R. Amin , Yamany B. Yamany b
a,
⇑
a
Basic and Applied Science Department, Faculty of Oral and Dentistry, Nahda University, New Beni-Sueff, Egypt
Faculty of Medicine and Medical Science, Taif University, Saudi Arabia
b
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 6 August 2011
Received in revised form 17 November 2011
Accepted 19 November 2011
Available online 26 November 2011
Anodic oxidation of Co, Cu, Zn, and Sn metals in an anhydrous acetone solution of 1,1-oxalyl-, malonyl- or
succinyl-bis(4-p-chlorophenylthiosemicarbazide) yields a new polynuclear complexes. The isolated com-
plexes have the general composition [M
2
(L)(H
2
O)
6
], L = pClSuTS and M = Co(II), Cu(II) or Sn(II),
(L)(ac)
[M
2
(L)(H O) O where M = Cu(II), Co(II) or Sn(II), L = pClOxTS and n = 2 or 6, and [M
2
n
]ꢀnH
2
2
2
]ꢀnH
2
O
where M = Co(II) or Zn(II), L = pClOxTS or pClSuTS and n = 2. The thermogravimetry (TG) and derivative
thermogravimetry (DTG) have been used to study the thermal decomposition of the investigated bisthi-
Keywords:
Metal(II) complexes
Electrochemical
Bis-thiosemicarbazide
Thermogravimetric
Antibacterial studies
Polynuclear complexes
⁄
osemicarbazide ligands and their metal complexes. The kinetic thermodynamic parameters such as: E ,
⁄ ⁄ ⁄
D
H ,
DS and DG are calculated using Horowitz–Metzger (HM) and Coats–Redfern (CR) equations. The
⁄
⁄
⁄
⁄
DG
kinetic thermodynamic parameters such as: E ,
DH ,
DS
and
are calculated from the DTG curves.
The tested compounds show a reasonable activity against four strains of Gram-negative bacteria; Esche-
richia coli, Pseudomonas aeruginosa species and Gram-positive bacteria; Bacillus cereus and Staphylococcus
aureus.
Ó 2011 Elsevier B.V. All rights reserved.
1
. Introduction
During the last 20 years ago, there was a rapid growth and inter-
with different anions have been synthesized, characterized [20] and
used as a chelating agent for the separation, preconcentration, and
determination of Cu(II) ions in saturated saline solutions by a cloud
point extraction technique [21]. In addition, the complexes of
4-ethyl and 4-(p-tolyl)-1-(pyridin-2-yl)thiosemicarbazides with
Pd(II), Pt(II) and Ag(I) were [22] show antibacterial activity to some
Gram-positive and Gram-negative bacterial strains. Thiosemicarba-
zide compounds have good ability to form complexes with metal
ions [20–26]. In this paper, we report the synthesis, thermal,
spectral and biological activity of new series of 1,1-oxalyl-, malo-
nyl- and succinyl-bis(4-p-chlorophenylthiosemicarbazide) com-
plexes formed during the electrochemical reaction through anodic
dissolution of Co, Cu, Zn and Sn metals.
est from the scientific researchers all over the world to discover,
isolate, prepare new natural [1–5] and new synthetic compounds
[
6–9] that have a good potential activity against microorganisms.
Spitteler et al. isolated new flavones from the Cameroonian medic-
inal plant Crotalaria lachnophora. They showed moderate inhibitory
activities against Escherichia coli and Klebsiella pneumonia [10–12].
The antimicrobial efficiencies of this class of compounds were
established by correlating the activity profile of each compound
with its structure and by comparing the activities of all the com-
pounds with each other based on their structure [1–5]. We have
previously studied the antimicrobial, antifungal and hypoglycaemic
effect of a series of bis and tetrakis-thiosemicarbazide and its Cu(II)
complexes against some organisms and albino mice. These com-
pounds were found to display significant decrease on plasma levels
of glucose by 26–39% [8]. Interest in thiosemicarbazide chemistry
has rapid growth for many years, largely as a result of its wide range
of uses as antibacterial [9], antifungal [13], antitumor [14], biolog-
ical activity [15,16], and its pharmacological applications [17–19].
2
. Experimental
2.1. Chemicals and materials
All the chemicals (Aldrich) were subjected to purification before
use. The solvents used were reagent grade. DMF (BDH) (Analar),
absolute ethanol and methanol (Fluka) were used as supplied. Ace-
4
-Ethyl-1-(pyridin-2-yl)thiosemicarbazide and its Cu(II) complexes
4
tone was dried over anhydrous MgSO before use. The metals (Alfa
Inorganics) used, Co, Cu, Zn, Sn and Au were purchased in the form
⇑
Corresponding author. Tel.: +20 1284969161; fax: +20 822246688.
E-mail address: rramin2010@yahoo.com (R.R. Amin).
of sheets (ꢁ2 cm ꢂ 2 cm, 2–3 mm thick). The oxide surface was re-
3
moved by treating the metal with conc. HNO for several minutes
0
022-2860/$ - see front matter Ó 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.molstruc.2011.11.024

R.R. Amin, Y.B. Yamany / Journal of Molecular Structure 1008 (2012) 54–62
55
and then washing with distilled water. Tetraethylammonium per-
chlorate, Et NClO , (BDH) was used as supplied [26].
2.5. Spectral, analytical and physical measurements
4
4
1
2
.5.1. IR, Raman and H NMR spectra
Infrared spectra for the samples were recorded by Perkin Elmer
FTIR 1605 using KBr pellets. Raman spectra of ligand and metal
complexes were recorded in the solid state on T-Nicolet FT-Raman
2
.2. General electrochemical procedures
The preparative results show that the direct electrochemical
(
USA) with a wavelength 1064 nm power according sample resolu-
oxidation of the metals in the presence of a ligand solution is a
one-step process and represents a convenient and simple route
to a variety of transition metal complexes. The apparatus used
in the electrochemical reaction consists of a tall-form 100 mL Pyr-
ex beaker containing 50 mL of the appropriate amount of the or-
ganic ligand dissolved in acetone solution. The cathode is a
platinum wire of approximately 1 mm diameter. In most cases,
the metal (2–5 g) was suspended and supported on a platinum
ꢄ1
tion was 8 cm at National Research Center, Cairo, Egypt. The
1
HNMR spectra were recorded on an Varian Mercury VX-300
1
NMR spectrometer. HNMR spectra were run at 300 MHz and
1
3
CNMR spectra were run at 75.46 MHz in deuterated dimethyl
sulphoxide (DMSO-d ). Chemical shifts are quoted in d and were
related to that of the solvents.
6
2
.5.2. Electronic and mass spectra
The electronic spectra of solutions were measured in UV/Vis
range (190–1100) nm using Helios UV Spectrometer at nano-
central laboratory of photo energy, Ain-Shams University. Mass
spectra were recorded at SHIMADZU GC MS-QP 1000 EX Micro ana-
lytical Center, Cairo Universal, Giza and Al-Azher University, Egypt.
f
wire [27]. Measurements of the electrochemical efficiency, E ,
for the M/L system (where L = ligand used) gave E = 0.5 ± 0.05 -
f
mol F-1 [28].
2
.3. Preparation of 1,1-oxalyl-bis(4-p-chlorophenylthiosemicarbazide)
4
(H pClOxTS)
2.5.3. Magnetic and molar conductance measurements
1
,1-Oxalyl-bis(4-p-chlorophenylthiosemicarbazide) was pre-
Magnetic measurements were carried out on a Sherwood Scien-
pared by adding 4-chloro-phenylisothiocynate (3.4 g, 0.02 mol) to
an alcoholic solution of oxalic acid dihydrazide (1.18 g ꢃ 0.01 mol).
The reaction mixture was refluxed for 1 h and left to cool with stir-
ring. The resulting white crystals were collected and washed with
ethanol and diethyl ether, respectively. The resulting solids were
tific magnetic balance using Gouy method. Molar conductivities of
ꢄ3
ꢄ1
freshly prepared 1.0 ꢂ 10 mol L DMSO solutions were mea-
sured using Jenway 4010 conductivity meter.
2.5.4. Microanalytical, magnetic and molar measurements
filtered hot, washed with hot distilled water, EtOH and Et
2
O then
Carbon and hydrogen contents were determined using a Per-
kin–Elmer CHN 2400 analyzer [28]. Magnetic measurements were
carried out on a Sherwood Scientific magnetic balance using Gouy
dried under vacuum over silica gel. Yield (3.5 g ꢃ 77%) with the
melting point at 193 °C. 1,1-malonyl- and 1,1-succinyl-bis-4-
ꢄ3
(p-chlorophenylthiosemicarbazide) were prepared by the same
method. Molar conductivities of freshly prepared 1.0 ꢂ 10 mol/
ꢄ3
way [29,30].
dm solutions of the complexes in DMSO were measured using
Jenway 4010 conductivity meter.
2.4. Electrochemical synthesis of 1,1-oxalyl-bis(4-p-
chlorophenylthiosemicarbazide) metal complexes
2.6. Thermal investigation
The ligand H
4
pClOxTS (0.231 g, 0.5 mmol) was dissolved in the
Thermogravimetric analysis (TG/DTG) were carried out in the
temperature range from 25 to 800 °C in a steam of nitrogen atmo-
sphere using Schimadzu TGA-50H thermal analyzer. The experi-
mental conditions were: platinum crucible, nitrogen atmosphere
with a 30 mL/min flow rate and a heating rate 10 °C/min.
minimum amount of DMSO (0.5 mL) followed by the addition of
0 mL of acetone and 2.5 mg of Et
0 mA was passed through the cell for 1 h, the amount of Cobalt
5
4
4 4
NClO . When the current
consumed is 59 mg and a dark green precipitate was formed (the
product is 0.3734 g, %yield 91 and E = 0.51). It was collected,
washed with diethyl ether and dried. The resulting dark green
powder was collected and analyzed as [Co (pClOxTS)(ac)
O) O. By the same procedure, Cu, Zn, and Sn complexes
f
2.7. Antibacterial investigation
2
2
(
H
2
4
]ꢀ3H
2
Bacterial cultures and growth conditions: Gram-negative E. Coli,
Pseudomonas aeruginosa species and Gram-positive Bacillus cereus,
were isolated and their data were gathered in Table 1.
Table 1
Analytical results for the prepared complexes of oxalyl, malonyl and succinyl-bis(4-p-chlorophenylthiosemicarbazide) and its metal complexes.
Compounds empirical formula
Formula weight Color
M.p. (°C) % Found (calc.)
Am ls
C
H
N
H
4
pClOxTS, (I) C16
Co (pClOxTS)(ac)
Cu (pClOxTS) (H
Zn (pClOxTS) (ac)
Sn (pClOxTS) (H O)
pClMaTS), (II) C17
(pClMaTS) (H O)
(pClMaTS) (H O)
(pClMaTS) (H O)
(pClMaTS) (H
pClSuTS, (III) C18
Co (pClSuTS) (H
Cu (pClSuTS) (H
Zn (pClSuTS)(ac)
Sn (pClSuTS) (H
H
14Cl
(H O)
O) ]6(H
]2(H O), (Ic) C22
], (Id) C16 14Cl
16Cl
]2(H
], (IIb) C17
], (IIc) C17
]2(H O), (IId) C17
18Cl
2
N
6
O
2
S
2
457.4
813.5
796.6
736.3
726.8
471.38
729.3
702.54
706.3
848.9
485.41
707.34
1011.8
764.4
826.9
White
Dark Green
Brown
Faint Yellow
Yellow
White
Dark Brown
Dark Brown
Yellowish White 213
Page
White
193
>300
>300
218
205
200
220
210
41.61 (42.02) 3.28 (3.09) 17.8 (18.38)
32.12 (32.48) 3.97 (4.46) 9.89 (10.33)
17
38
[
[
[
[
(
[
[
[
[
2
2
2
4
]3(H
O), (Ib) C16
26Cl
2
O), (Ia) C22
24Cl
Zn
H
36Cl
2
Co
2
N
6
O
11
S
2
2
2
6
2
H
2
Cu
2
6
N O
14
S
2
24.1 (24.12)
4.03 (4.3)
10.32 (10.55) 40
2
2
2
H
2
2
N
6
O
6
S
2
35.55 (35.89) 3.21 (3.56) 11.88 (11.41) 30
2
2
2
H
2
Sn
2
N
6
O
4
S
2
26.33 (26.44) 2.2 (1.94)
43.18 (43.32) 3.08 (3.42) 17.6 (17.83)
27.7 (28)
11 (11.56)
35
20
H
4
H
2
N
6
O
2
S
2
Co
Cu
Zn
Sn
2
2
6
2
O), (IIa) C17
24Cl
24Cl
H
28Cl
2
Co
2
N
6
O
10
S
2
4.25 (3.87) 11.35 (11.52) 37
2
2
6
H
H
2
Cu
Zn
28Cl
2
N
6
O
8
S
2
29.86 (29.06) 3.39 (3.44) 11.5 (11.96)
29.07 (28.91) 3.30 (3.43) 11.40 (11.9)
24.01 (24.05) 3.22 (3.32) 9.34 (9.9)
35
38
36
2
2
6
2
2
N
6
O
8
S
2
2
2
O)
6
2
H
2
Sn
2
N
6
O
10
S
2
243
197
217
>300
235
275
H
4
H
2
N
6
O
2
S
2
44.76 (44.54) 3.79 (3.74) 17.01 (17.31) 10
[
[
[
[
2
2
O)
O)
] 2(H
O) ], (IIId) C18
6
], (IIIa) C18
H
H
26Cl
34Cl
2
Co
N
2 6
O
8
S
2
Dark Brown
Green
Page
31.05 (30.56) 4.25 (3.7)
11.3 (11.88)
38
35
2
2
6
], (IIIb) C18
2
Cu
4
N
6
O
14
S
4
21.32 (21.37) 3.34 (3.39) 7.9 (8.31)
37.84 (37.71) 3.84 (3.96) 11.04 (10.99) 32
26.11 (26.15) 3.3 (3.17) 9.68 (10.16) 36
2
2
2
O), (IIIc) C24
H
30Cl
2
Zn
2
6
N O
6
S
2
2
2
6
H26Cl
2
Sn
2
N
6
O
8
S
2
Pale Yellow

5
6
R.R. Amin, Y.B. Yamany / Journal of Molecular Structure 1008 (2012) 54–62
ꢄ1
ꢄ1
Staphylococcus aureus species and fungal Aspergillus fumingatus,
Candida albicans were used as test microorganisms. The surface
of the medium was inoculated and covered with the tested organ-
isms using Swab. The agar surface was allowed to dry from 3 to
is observed at 1591–1601 cm and 1593–1596 cm in IR and
Raman, respectively, suggesting the participation of carbonyl group
in the coordination to metal ions during the enolization [34,35]. This
feature is further supported by the shift of
m
(NAN) band in the free
ꢄ1
5
min before applying disks. The disks were dipped into a beaker
ligand from 902–923 cm
in IR to higher frequencies, 924–
975 cm upon complexation [32,36]. On the other hand, the partic-
ipation of the deprotonated thiol sulfur in coordination was indi-
cated by the shift of the IR bands at 814–831 cm (at 824 cm in
the Raman) in the free ligands to lower frequencies in the IR bands
of the metal complexes at 755–777 cm (at 779–780 cm in the
Raman) [33,37]. The spectra of the complexes show that new bands
ꢄ1
of the chemicals using sterile forceps and placed them in the pre-
vious medium. Cultures plates of bacteria were incubated for
grown at 37 °C for 48 h. Chloramphenicol was used as a standard
antibacterial agent and Terbinafin was used as a standard anti-
fungal agent. The test was done using the diffusion agar technique,
at Al-Azher University, Egypt.
ꢄ1
ꢄ1
ꢄ1
ꢄ1
ꢄ1
in the IR and Raman near 395–428 and 490–505 cm range may as-
sign to
spectra of the complexes compared with ligands, indicates that
bands due to (NH), (C@O) and (C@S) are absent and new bands
appear at due to (N@C) and (CAS), respectively, suggesting
m(MAN) and m(MAO), respectively [38,39]. The IR and Raman
3
. Results and discussion
m
m
m
3.1. Electrochemical reaction mechanism
m
m
removal of both the hydrazinic protons via enolisation and thioen-
olisationand bonding of theresulting enolic oxygen and thiolatosul-
fur takes place with Co(II), Cu(II), Zn(II) and Sn(II). As an example, the
Raman spectrum of complex IIc when compared with ligand II indi-
f
Measurements of the electrochemical efficiency, E , defined as
moles of metal dissolved per Faraday of electricity, for the Co/L sys-
ꢄ1
tem (where L = ligand) gave E
f
= 0.5 ± 0.05 mol F . The values
show that the reaction of the ligand with cobalt anode is compat-
ible with the following steps 1 and 2 [26–28].
cates that bands due to
new bands appear at ca. 1593 and 779 cm due to
m(CAS), respectively suggesting removal of both the hydrazinic pro-
m(NH), m(C@O) and m(C@S) are absent, but
ꢄ1
m
(N@C) and
(
1) The first step:
tons via enolisation and thioenolisation and bonding of the resulting
enolic oxygen and thiolato sulfur takes place with Zn(II). The spectra
2
ꢄ
Cathode : H
4
L þ 2e ! H
2
L
þ H
2
ðgÞ
ð1Þ
ð2Þ
of all the complexes show that new bands in the IR and Raman near
2
ꢄ
ꢄ1
Anode : H
2
L
þ Co ! CoH
2
L þ 2e
3
95–428 and 490–505 cm
range may assign to m(MAN) and
m(MAO), respectively [38–40].
(
2) The second step:
2
ꢄ
Cathode : CoH
2
L þ 2e ! CoL þ H
2
ðgÞ
ð3Þ
ð4Þ
3.3. Electronic spectra
2ꢄ
The electronic spectra for all three ligands and their metal com-
plexes were recorded in DMSO (Figs. 4–6) and the spectral data
are listed in Table 3. There are two main absorption bands in the
Anode : CoL þ Co ! Co L þ 2e
Anodic oxidation of Co, Cu, Zn, and Sn metals in an anhydrous
acetone solution of 1,1-oxalyl-bis(4-p-chlorophenylthiosemicar-
2
spectra of the ligands and their complexes; the first band at
⁄
bazide yields complexes have a general formula [Co
c) (H O) ], [Cu (pCl-OxTSC)(H O) ], [Zn (pCl-OxTSC)(ac)
OxTSC)(H O) ] chelation was investigated based on elemental
2
(pCl-OxTSC)(a-
2
3
56–296 nm and assigned to
p
–p
[20–23] and the second at 304–
⁄
2
2
4
2
2
6
2
2
], [Sn (pCl
2
56 nm due to n–
p
intraligand transitions [26–28]. These absorp-
-
2
2
tions also present in the spectra of the Co(II), Cu(II), Zn(II) and Sn(II)
complexes but they are shifted.
The electronic spectrum of [Co
bands characteristic for an octahedral geometry [26–30]. The spec-
analysis, conductivity, magnetic moment, spectral (UV Vis IR, Ra-
man, HNMR, mass) and thermal studies. The elemental analysis
and some physical data of the resulted compounds are given in Table
. The molar conductivity values for all the isolated complexes, in
1
2
(pClOxTS)(ac)
2
(H
2 4 2
O) ]ꢀ3H O has
ꢄ1
1
trum shows two bands at 20,600 and 31,950 cm assigned to the
4
4
4
4
DMF or DMSO indicate non-electrolytes nature.
T
1
g ? A
2 2 1 1 3
g (m ) and T g ? T g (P) (m ) transitions, respectively,
in an octahedral structure. These bands were used to calculate
4
4
3.2. Infrared and Raman spectra
the third spin-allowed band, T
parameters, B, b and the
1
g ? T
1
g [26–30]. The ligand field
ꢄ1
m
2
/m
1
were calculated to be 1060 cm , 1.2
The infrared and Raman spectral assignments of the ligands, pCl-
OxTSC, pCl-MaTSC and pCl-SuTSC, and its reported complexes are
and 2.2, respectively, and are in good agreement with those re-
ported for octahedral Co(II) complexes. The electronic spectrum
listed in Table 2. They has the characteristic thioamide moiety
of [Cu
2
(pClOxTS)(H
2
O)
6
]ꢀ6H
2
O, shows shoulders at 32,260 and
ꢄ1
2
2
(AHNAC(S)NHA), which can be present in either thione or thiol
20,600 cm . The observed bands are due to
1
B g ? Eg and
2
2
form [31]. The IR and Raman spectra of the discussed ligands show
1 1
B g ? A g, on the basis of octahedral geometry [20–23].
ꢄ1
the absence of absorption bands in 2500–2600 cm regions indi-
cating the presence of the free ligands in thione form [32]. The
Molecular modeling structure of 1,1-oxalyl-, malonyl- and succi-
nyl-bis(4-p-chlorophenylthiosemicarbazide were shown as in
Figs. 1–3. The NH vibration of compounds I, II and III has bands ap-
3.4. Magnetic susceptibility
The observed values of the magnetic moment for the complexes
are generally diagnostic of the coordination geometry about the
ꢄ1
7
pears in IR spectra at 3306–3310, 3196, and 3092–3111 cm
metal ion. Co(II) has 3d and should exhibit a magnetic moment
ꢄ1
ranges, (at 3301–3307, 3199 and 3095 cm in Raman). The bands
expected for three unpaired electrons. The magnetic moment ob-
served for the Co(II) complexes is 3.2 BM which is consistent with
the octahedral stereochemistry of the complexes.
occurring at 1651–1670, 1400–1402, 1341–1342, 902–923 and
ꢄ1
8
14–831 cm
ranges are assigned to
m(C@O), thioamide I
[
b(NH) +
m
(CN)], thioamide II [
m
(CN) + b(NH)],
m
(NAN) and
m
(C@S),
ꢄ1
1
respectively in IR, (at 1650, 1405, 1355, 1090 cm Raman) [20].
3.5. H NMR spectra
pCl-OxTSC, pCl-MaTSC and pCl-SuTSC shows a strong IR band at
ꢄ1
ꢄ1
1
1
651–1670 cm , observed at 1635–1650 cm
which is corresponding to the carbonyl, (C@O), group [33]. In the
spectra of the complexes, the shift of these bands to lower frequency
in the Raman,
The HNMR spectra of compounds Ic and IIc on comparing with
m
those of the ligands indicate that the ligands acts as a hexadentate
through the nitrogen atom of C@N oxygen atom of C@O and sulfur

R.R. Amin, Y.B. Yamany / Journal of Molecular Structure 1008 (2012) 54–62
57
Table 2
Significant IR and Raman spectral bands, cm , of the ligand oxalyl, malonyl, succinyl-bis(4-p-chlorophenylthiosemicarbazide) and the metal complexes.
ꢄ1
The compounds
Assignments
4
2
m
N H
3306
307
m
N H
m
NH
m
CH-arom.
m
CH-aliph.
m
C@O
bNH/
mCN
m
CN/bNH
dOH
m
N–N
m
C@S/
mCAS
m
MAO
mMAN
H
4
pClOxTS, I
3196
3199
3181
3175
3174
3092
3064
3063
3055
3030
3046
3062
3005
2940
2935
2932
2941
2940
2931
2940
2925
2940
2934
2980
2934
2938
2933
2940
2940
2934
2943
2938
2938
2931
2940
2925
1651
1402
1342
–
902
831
–
–
3
Co-complex, Ia
Cu-complex, Ib
Zn-complex, Ic
3234
3230
3211
205
3300
3111
3109
3100
1595
1601
1593
1594
1595
1595
1657
1635
1595
1599
1591
1593
1599
1670
1650
1595
1597
1595
1596
1599
1593
1422
1443
1425
1398
1375
1362
1307
1306
1308
934
941
924
755
756
777
779
775
780
814
824
743
772
777
779
777
827
505
500
495
415
420
415
395
417
416
–
3
Sn-complex, Id
3198
3000
3111
1435
1398
1308
–
924
902
490
–
3
205
3196
201
3179
3180
3194
209
3197
3196
H
4
pClMaTS, II
3310
3005
1400
1405
1420
1431
1416
1341
1355
1400
1400
1400
1395
1400
1341
1355
1368
1379
1400
1390
1400
1390
3
Co-complex, IIa
Cu-complex, IIb
Zn-complex, IIc
3237
3238
3305
3109
3111
3105
3034
3053
3005
1306
1310
1310
1315
1308
–
935
945
924
493
501
490
421
428
418
3
Sn-complex, IId
H pClSuTS, III
4
3305
3310
3111
3107
3095
3115
3115
3109
3007
3005
3005
3032
3039
3001
3
3007
3005
1440
1400
1405
1418
1450
1418
925
923
490
–
421
–
3
201
Co-complex, IIIa
Cu-complex, IIIb
Zn-complex, IIIc
3237
3238
3305
3220
3202
3200
1307
1319
1310
1319
1308
1294
975
960
966
755
775
777
500
490
492
415
425
421
004
Sn-complex, IIId
3305
300
3198
3115
3100
1445
1450
964
773
495
415
3
Raman data are in bolds and italic.
Fig. 1. Molecular modeling of 1,1-oxalyl-bis(4-p-chlorophenylthiosemicarbazide).
Fig. 3. Molecular modeling of 1,1-succinyl-bis(4-p-chlorophenylthiosemi-
carbazide).
1
1
a: H pClOxTS
4
b: [Co (pClOxTS)(ac) (H O) ].3H O
2
2
2
4
2
1
d
1c: [Cu (pClOxTS)(H O) ].6H O
2
2
6
2
1
1
d: [Zn (pClOxTS)(ac) ].2H O
2 2 2
e: [Sn (pClOxTS)(H O) ]
2
2
2
2
1
c
Fig. 2. Molecular modeling of 1,1-malonayl-bis(4-p-chlorophenylthiosemi-
carbazide).
1
b
1
1a
atom of C@S. HNMR spectrum of zinc(II) complex is in agreement
1e
with the suggested coordination through the C@N and C@S groups
by the presence of the signals of (two from 2NH amine groups and
two protons from 2NH amide groups).
0
3
00
350
400
450
500
550
600
650
700
1
Wavelength (nm)
–
(H
micarbazide),
.95(N6,18H amine group), 3.6(CN9,21H, 6.6–7.5 aromatic).
4
pClOxTS), HNMR of 1,1-oxalyl-bis(4-p-chlorophenylthiose-
1
d
(ppm): 9.75(N5,17H amide group),
Fig. 4. The electronic spectra of 1,1-oxalyl-bis(4-p-chlorophenylthiosemicarbaz-
ide), H pClOxTS, and its metal complexes.
1
4

5
8
R.R. Amin, Y.B. Yamany / Journal of Molecular Structure 1008 (2012) 54–62
2
2
1
1
0
0
.5
.0
.5
.0
.5
.0
Table 3
1
e
1
a: (H pClMaTS)
The electronic spectra data of oxalyl, malonyl and succinyl-bis(4-p-chlorophenylthi-
osemicarbazide) and its metal complexes.
4
1
c
1b: [Co (pClMaTS)(H O) ].2H O
2
2
6
2
1
1
1
c: [Cu (pClMaTS)(H O) ]
2
2
6
ꢄ1
Compounds
k
max nm (cm
)
d: [Zn (pClMaTS)(H O) ]
1b
2
2
6
⁄
⁄
e: [Sn (pClMaTS)(H O) ].2H O
p
–p
n–
p
d–d Transition
2
2
6
2
I
256
39,060)
260
38,460)
268
37,300)
314
(31,850)
313
(31,950)
310
(32,260)
317
(31,550)
324
(30,860)
344
(29,070)
342
(29,240)
358
(27,930)
344
(29,070)
330
(30,300)
328
(30,490)
356
(28,090)
320
(31,250)
332
(30,120)
304
(32,890)
–
–
–
(
1
d
Ia
494
559
578
(17,300)
–
(
(20,240)
486
(17,889)
540
Ib
(
(20,600)
–
(18,520)
–
Ic
265
(37,740)
266
–
–
–
1
a
Id
–
–
–
–
(
37,600)
287
34,840)
II
(
IIa
IIb
IIc
IId
III
288
(34,720)
308
462
485
522
(19,160)
524
(19,080)
–
3
00
350
400
450
500
550
600
(21,650)
466
(20,620)
493
Wavelength (nm)
(
32,470)
(21,460)
–
(20,280)
–
Fig. 5. The electronic spectra of 1,1-malonyl-bis(4-p-chlorophenylthiosemicarbaz-
ide), H pClMaTS, and its metal complexes.
284
(35,210)
288
4
–
–
–
–
–
–
(
34,720)
264
37,880)
(
3
2
2
1
1
0
0
.0
.5
.0
.5
.0
.5
.0
1
1
1
1
1
a: H4 pClSuTS
IIIa
IIIb
IIIc
IIId
296
(33,780)
256
(39,060)
280
540
600
622
(16,080)
–
b: Co (pClSuTS)(H O)
2
2
6
(18,520)
543
(16,670)
610
c: Cu (pClSuTS)( H2O)
2
6
d: [Zn (pClSuTS)(ac) ] 2(H O)
(18,420)
–
(16,390)
–
2
2
2
e: Sn2 (pClSuTS)(H2O)6
–
–
(
35,710)
260
38,460)
–
–
(
1
a
1
e
1d
1b
1
c
liberation of 3H
calc. = 28.6%) is due to the removal of 2 acetone, 4 water and N
fragments. The third step at 390–707 °C (obs. = 18.3%, calc. = 18.9%)
is accounted for the removal of (C ) fragment. The fourth step at
07–990 °C (obs. = 22.8%, calc. = 22.8%) is accounted for the removal
of (C Cl ) fragment. The decomposition ended with 2CoO and 3/
2C (obs. = 23.7%, calc. = 22.9%) (see Table 4).
The TG curve of Ib complex indicates that the mass change be-
2
O. The second step at 175–390 °C (obs. = 29.2%,
3 3
H
3
00
350
400
450
500
550
600
4
3 2
N S
Wavelength (nm)
7
9
H
7
2
Fig. 6. The electronic spectra of 1,1-succinyl bis(4-p-chlorophenylthiosemicarbaz-
ide), H
4
pClSuTS, and its metal complexes.
2
gins at 25 °C and continuous up to 1000 °C. The first and second
mass loss corresponds to the liberation of the 12water molecules
and two (HCN) fragment (obs. = 34.4%, calc. = 33.9%) at 25–342 °C.
The third step occurs in the range 342–475 °C and corresponds to
1
–
[Zn
2
2
(pClOxTS)(ac)
2
]ꢀ2H
2 3
O HNMR d (ppm): 1.19(CH acetone),
.7(H O) (NH amide groups disappeared), (NH amine groups
2
disappeared), 3.5(9,21CNH aromatic), 6.6–7.5(CH-aromatic
shifted).
the loss of (CN
4
S) (obs. = 12.8%, calc. = 12.6%). The fourth and fifth
4
(H d (ppm): 9.7(7,19NH amide group),
pClSuTS) 1HNMR
–
–
decomposition step are final decomposition organic ligand to the
1
.95(8,20NH amine group),4(11,23CNH aromatic), 2.5(3,4CH
2
)
(
13
C H
8 2 2 2
Cl ), 1/2S , O fragments and 2Cu metal residual atoms.
6
.6–7.75(CH-aromatic).
(
obs. = 52.8%, calc. = 53.4%). From the previous discussion, the
2 2 2 2 3
(pClSuTS)(ac) ]2(H O), 1.2(CH
O) 1HNMR d (ppm): 1.1(H
[Zn
acetone) (NH amide groups disappeared), (NH amine groups
structure of Ib complex may have the octahedral bi-nuclear com-
plex as shown in Scheme 1.
disappeared), 2.5(CH
shifted).
2
), 4(CNH aromatic), 6.6–7.75(CH-aromatic
Ic complex was thermally decomposed in mainly five decompo-
sition steps within the temperature range 25–700 °C. The first
decomposition step (obs. = 20.64%, calc. = 20.64%) at 25–245 °C,
may be attributed to the liberation of two water and two acetone
molecules. The second step at 245–386 °C (obs. = 23.4%, calc. =
3
.6. Thermogravimetric analysis
Thermogravimetric analysis curves (TGA and DTG) of I, Ia, Ib, Ic
23.6%) is accounted for the removal of the 2(HCN), 2N
ments. The third step found within the temperature 386–700 °C
(obs. = 19.7%, calc. = 19.96%) is accounted for the removal of Cl
and C molecule. The rest of the ligand molecule was removed
2 2
and S frag-
and Id are discussed as mentioned in Table 4. Compound I was ther-
mally decomposed within the temperature range 25–700 °C. The
first step with weight loss of 42.5% (calc. 42.4%) at 25–237 °C may
2
6
H
4
be attributed to the liberation of 2(N
second step at 237–337 °C (obs. = 30.2%, calc. = 30.4%), is accounted
for the removal of 1/2O , Cl and C . The decomposition ended
with C10 residue (obs. = 27.3%, calc. = 27.1%).
The complex Ia was thermally decomposed in five steps. The first
step (obs. = 6%, calc. = 6.6%) at 25–175 °C may be attributed to the
2
H
2
), 2(HCNS) and 1/2O
2
. The
with a final residue of (C
calc. = 35.7%).
Id complex is thermally stable up to 50 °C and decomposition
beyond this temperature as indicated by the first loss step in the
TG curve. First step, the mass loss at 226 °C corresponds to the loss
of two water and 2(HCN) molecules (obs. = 12.6%, calc. = 12.4%).
8 4
H ), (ZnO) and zinc metal (obs. = 36.3%,
2
2
4
H
4
H
4

R.R. Amin, Y.B. Yamany / Journal of Molecular Structure 1008 (2012) 54–62
59
Table 4
The thermal data of 1,1-oxalyl-bis(4-p-chlorophenylthiosemicarbazide) and its metal complexes.
Compound
Steps
Temperature range (°C)
TG weight loss (%)
Assignment
T
max
Calc.%
Found%
I
1
2
3
25–237
237–337
More than 337
42.40
30.40
27.10
42.50
30.20
27.30
2(N
1/2O
C H
10 4
2
H
2
), 2(HCNS) and 1/2O
2
fragments
205
280
565
2
, Cl and C
2
4 4
H
Ia
1
2
3
4
5
25–175
175–390
390–707
707–990
6.60
6 .00
29.20
18.30
22.80
23.70
3 Water
3 3
2 Acetone, 4 water and N H
166
278
777
869
28.50
18.90
22.80
22.90
(C
(C
4
N
H
3
S
2
)
9
7
Cl
2
)
More than 990
2CoO and residual carbon 3/2C
2
Ib
Ic
Id
1,2
3
25–342
342–475
More than 475
33.90
12.60
53.40
34.40
12.80
52.80
12 Water and 2(HCN)
187, 271
405, 480
840
(CN
(C13
4
S)
Cl
4,5
H
8
2
), (S), (O
2
) molecules and 2Cu(II)metal
9
78
1
2
3
4
25–245
245–386
386–700
More than 700
20.64
23.60
19.96
35.70
20.64
23.40
19.70
36.30
Two water and two acetone molecules
2(HCN), 2N and S
Cl and C
(C ), (ZnO) and zinc metal residue
228
319
493
649
2
2
2
6 4
H
8 4
H
1
2
3
4
25–226
226–322
322–560
More than 560
12.40
16.50
16.90
54.10
12.60
16.20
17.20
54.00
Two water and 2(HCN) molecules
and 2N
and C
, (SnO) and Sn metal residue
224
301
530
S
2
2
Cl
2
4 4
H
10 4
C H
Table 5
Kinetic parameters using the Coats–Redfern (CR) and Horowitz–Metzger (HM) operated for (H
4
pClOxTS) and its complexes.
Compound
Stage
Method
Parameter
r
ꢄ1
ꢄ1
ꢄ1 ꢄ1
ꢄ1
ꢄ1)
E (J mol
)
A (s
)
D
S (J mol
K
)
D
H (J mol
)
D
G (J mol
5
10
12
1
5
5
I
1st
1st
1st
1st
1st
CR
HM
1.12 ꢂ 10
1.28 ꢂ 10
5.14 ꢂ 10
6.33 ꢂ 10
1.10 ꢂ 10
1.31 ꢂ 10
8.04 ꢂ 10
1.07 ꢂ 10
1.07 ꢂ 10
1.50 ꢂ 10
ꢄ5.68 ꢂ 10
ꢄ1.58 ꢂ 10
1.08 ꢂ 10
1.24 ꢂ 10
1.35 ꢂ 10
1.32 ꢂ 10
1.43 ꢂ 10
1.56 ꢂ 10
1.35 ꢂ 10
1.31 ꢂ 10
1.50 ꢂ 10
1.51 ꢂ 10
0.9981
0.9961
5
1
5
5
4
4
3
2
4
5
5
Ia
Ib
Ic
Id
CR
HM
7.99 ꢂ 10
6.60 ꢂ 10
ꢄ1.75 ꢂ 10
ꢄ1.77 ꢂ 10
4.68 ꢂ 10
5.87 ꢂ 10
0.9920
0.9929
3
2
4
5
9
1
5
5
5
CR
HM
7.01 ꢂ 10
2.96 ꢂ 10
ꢄ6.04 ꢂ 10
ꢄ1.01 ꢂ 10
1.06 ꢂ 10
1.27 ꢂ 10
0.9995
0.9991
5
12
1
5
4
5
2
1
4
5
CR
HM
7.21 ꢂ 10
2.29 ꢂ 10
ꢄ1.38 ꢂ 10
ꢄ8.98 ꢂ 10
7.59 ꢂ 10
1.02 ꢂ 10
0.9968
0.9985
5
8
5
5
4
5
7
2
4
5
5
CR
HM
8.61 ꢂ 10
1.71 ꢂ 10
1.65 ꢂ 10
ꢄ1.11 ꢂ 10
ꢄ6.59 ꢂ 10
8.2 ꢂ 10
1.37 ꢂ 10
1.38 ꢂ 10
0.9938
0.9955
9
1
5
32.75 ꢂ 10
1.05 ꢂ 10
moved on the fourth step within the temperature of more than
5
60 °C (obs. = 54%, calc. = 54.1%).
Ligand II was thermally decomposed in mainly decomposition
steps, Table S1, within the temperature range successive decompo-
sition steps at 25–700 °C. The first decomposition step
(
obs. = 39.14%, calc. = 39%) at 25–245 °C, may be attributed to the
liberation of the 2(HNCO), 2H S and 2(NH) fragments. The second
decomposition step at 245–345 °C (obs. = 32.8%, calc. = 32.5%), is
accounted for the removal of 2(HCN), (C ) and Cl . The decompo-
sition of the ligand molecule ended with a final (C17 ) residue
obs. = 28%, calc. = 28.3%).
The complex IIa was thermally decomposed in five steps within
2
2
H
2
2
H
2
(
the temperature range 25–1000 °C. The first step (obs. = 5.2%,
calc. = 4.94%) at 25–188 °C, may be attributed to the liberation of
Scheme 1. Suggested octahedral structure for, Ia, copper oxalyl-bisthiosemicarbazide
complex.
the two H
O molecules. The second step at 188–448 °C (obs. =
3.1%, calc. = 33.5%), is accounted for the removal of 6H O, 2N
(HCN), and C fragments. The decomposition third step at
2
3
2
2
2
,
2 2
H
Continuous mass loss in the TG curve from 226 to 322 °C corre-
448–760 °C (obs. = 23.4%, calc. = 22.9%) is accounted for the removal
of S , Cl and O molecules. The fourth step found at 760–885 °C
(obs. = 21.8%, calc. = 22.5%) is accounted for the removal of CH
and C12 fragments. The rest of the ligand molecule was removed
with a final 2Co atom (obs. = 17.3%, calc. = 16.5%).
The TG curve of IIb complex indicates that the mass change be-
gins at 25 °C and continuous up to 1000 °C. The first and second
sponds to the loss of
S
2
and 2N
2
molecules (obs. = 16.2%,
2
2
2
calc. = 16.5%). The decomposition third step found within the tem-
perature 322–560 °C (obs. = 17.2%, calc. = 16.9%) which is reason-
4
H
4
ably accounted for by the removal of Cl
rest of organic moiety and the final decomposition of the organic
ligand to the C10 , (SnO) and Sn metal residue molecules was re-
2 4 4
and C H molecule. The
H
4

6
0
R.R. Amin, Y.B. Yamany / Journal of Molecular Structure 1008 (2012) 54–62
mass loss corresponds to the liberation of the 6H
obs. = 16.4%, calc. = 15.4%) at 25–245 °C. The third step occurs in
the range 245–475 °C and corresponds to the loss of N , 2(HCN),
, and O (obs. = 20.6%, calc. = 20.5%). The fourth step at 475–
65 °C (obs. = 42.4%, calc. = 42.5%) is accounted for the removal of
, S and Cl ) fragments. The fifth steps are final decomposi-
2
O molecules
(
2
N
2
H
2
2
7
(
C
13
H
8
2
2
tion organic ligand to the C
calc. = 21.5%).
2
and 2Cu residual. (obs. = 20.6%,
The complex IIc was thermally decomposed in mainly four steps
within the temperature range 25–700 °C. The first decomposition
step (obs. = 15.5%, calc. = 15.3%) at 25–224 °C, may be attributed
to the liberation of 6H
obs. = 26.5%, calc. = 26.9%) is accounted for the removal of 2N
, 1/2O and 2(HCN) fragment. The decomposition third step found
within the temperature 338–643 °C (obs. = 18.6%, calc. = 18.2%) is
accounted for the removal of 1/2O , Cl , CH and C fragments.
The rest of the molecule was removed with a final residue metal
of 2Zn and C12 fragment (obs. = 39.4%, calc. = 39.5%).
2
O. The second step at 224–338 °C
(
S
2
,
2
2
2
2
4
2 2
H
Scheme 2. Suggested structure for succinyl bisthiosemicarbazide metals complexes.
H
4
The complex IId is thermally stable up to 50 °C and decomposi-
tion beyond this temperature as indicated by the first and second
loss steps in the TG curve. First and second steps, the mass loss
The complex IIIc was thermally decomposed in mainly three
decomposition steps within the temperature range 25–700 °C. The
first decomposition step (obs. = 20%, calc. = 19.9%) within the tem-
perature range 25–236.8 °C, may be attributed to the liberation of
two water and two acetone molecules. The decomposition second
step found within the temperature 236.8–365 °C (obs. = 25.3%,
calc. = 25.38%) which is reasonably accounted for by the removal
at 322 °C corresponds to the loss of 8H
ecules (obs. = 24.7%, calc. = 25.2%). Continuous mass loss in the TG
curve from 322 to 504 °C corresponds to the loss of 1/2S and
HNCO molecules (obs. = 9.3%, calc. = 8.8%). The rest of organic
moiety NH , N and 1/2S molecules was removed on the fourth
step at 504–589 °C (obs. = 9.56%, calc. = 9.1%). The final decomposi-
tion of the Cl and Sn the residual (obs. = 56.44%, calc. =
6.8%).
All the steps of decomposition for theligand III and its metal com-
2
O and HNCO and HCN mol-
2
3
2
2
of 2(HCN) 2(HNCO) 2CH and N
the ligand molecule ended with a final residue metal of Zn(II) and
contaminated 2Cl , S , (C ) and 2Zn (obs. = 54.7%, calc. = 54.66%).
2
fragment. The decomposition of
2
, C14
H
6
2
2
2
6 4
H
5
The complex IIId is thermally stable up to 50 °C and decompo-
sition beyond this temperature as indicated by the first loss step in
the TG curve. First step, the mass loss at 239 °C corresponds to the
loss of six water molecules (obs. = 13%, calc. = 13.1%). Continuous
mass loss in the TG curve from 239 °C to 321 °C corresponds to
the loss of 2HCN and 2N fragments (obs. = 12.7%, calc. = 13.3%).
2
The rest of the ligand molecule was removed and fifth step the
decomposition of the ligand molecule ended with a final residue
plexes were described in Table S3. Ligand III was thermally decom-
posed in mainly decomposition steps within the temperature range
successive decomposition steps within the temperature range
2
5–700 °C. The first decomposition step (obs. = 36%, calc. = 35.8%)
within the temperature range 25–234 °C, may be attributed to the
liberation of the 2(HCN), 2N and S fragments. The second decom-
position steps found within the temperature range 234–334 °C
obs. = 32.1%, calc. = 32.3%), which is reasonably accounted by the
removal of Cl , O and C . The decomposition of the ligand mole-
cule ended with a final C12 10 residue (obs. = 31.86%, calc. = 31.7%).
2
2
metal of two Tin atoms and contaminated of, C16
H12, fragments
(
(
obs. = 53.5%, calc. = 53.4%). From the previous discussion, the
2
2
4 6
H
H
structure of Co(II) and Sn(II) succinyl bisthiosemicarbazide metals
complexes may have the octahedral bi-nuclear structure as shown
in Scheme 2.
The complex IIIa was thermally decomposed in four successive
decomposition steps within the temperature range 25–1000 °C.
The first decomposition step (obs. = 31.9%, calc. = 32%) within the
temperature range 25–332 °C, may be attributed to the liberation
3.7. Kinetic studies
of the 6water molecules, 2(HCN) and N
decomposition steps found within the temperature range 332–
50 °C (obs. = 16.9%, calc. = 16.8%), which is reasonably accounted
by the removal S , O and C fragments. The decomposition third
step found within the temperature 550 °C –895 °C (obs. = 24.6%,
calc. = 24.5%) which is reasonably accounted for by the removal
2 2
H fragments. The second
1,1-Oxalyl-, malonyl- and succinyl-bis(4-p-chlorophenylthiose-
micarbazide) ligand and its Co(II), Cu(II), Zn(II) and Sn(II) com-
plexes thermodynamic activation parameters of decomposition
5
2
2
2 2
H
⁄
processes of hydrated complexes, namely activation energy, E , en-
⁄
⁄
thalpy,
D
H , entropy,
D
S , and Gibbs free energy change of the
⁄
of Cl
removed and fourth the decomposition of the Co(II)/L complex
molecule ended with a final 3/2C and Co metal is cobalt residue
obs. = 26.6%, calc. = 26.8%).
The TG curve of complex IIIb indicates that the mass change be-
2
, and C
8
H
6
fragments. The rest of the ligand molecule was
decomposition,
D
G , were evaluated graphically, Figs. S1–S15, by
employing the Coats–Redfern and Horowitz–Metzger relations
[41–46]. The thermodynamic parameters for oxalyl-thiosemicar-
bazide complexes were calculated and summarized in Table 5.
All the thermodynamic parameters for the rest of materials were
also calculated. The data are summarized in Tables S2 and S4.
The high values of the activation energy illustrated to the thermal
2
2
(
gins at 25 °C and continuous up to 1000 °C. The first mass loss corre-
sponds to the liberation of the 10water molecules (obs. = 17.8%,
calc. = 17.8%) within the temperature range 25–465 °C. The second
decomposition steps found within the temperature range 465–
stability of the complexes.
is positive and S is negative. The reaction for which
and S is negative considered as unfavorable or non spontaneous
reactions.
D
G is positive for reaction for which
DH
D
D
G is positive
7
00 °C (obs. = 15%, calc. = 14.8%), which is reasonably accounted
by the removal of 2(HCN), 2N and 2(CH ) fragments. The third
decomposition step occurs in the range 700–910 °C and corresponds
to the loss of Cl , 2(C ) and 2S (obs. = 33.9%, calc. = 34.7%). The
D
2
2
The activation energies of decomposition of ligand I and its me-
ꢄ1
2
H
6 4
2
tal complexes were in the range 57.3–120 kJ mol . The high val-
fourth and fifth steps are the final decomposition (obs. = 33.3%,
calc. = 32.6%) which is reasonably accounted for by the removal of
carbon and 4CuO.
ues of the activation energy illustrated to the thermal stability of
the complexes. The correlation coefficients of the Arrhenius plots
of the thermal decomposition steps were found to lie in the range

R.R. Amin, Y.B. Yamany / Journal of Molecular Structure 1008 (2012) 54–62
61
0
.9925–0.9993 showing a good fit with linear function. It is clear
of thioketo (C@S) groups. On the basis of the magnetic measure-
ments octahedral geometry are suggested for all investigated
complexes. The thermodynamic activation parameters of decomposi-
tion processes of thematerials were evaluated graphically. It is clear that
that the thermal decomposition process of ligand I and its
complexes are thermally stable. The entropy of activation had neg-
ative values in all the complexes, which indicates that the decom-
position reactions proceed with a lower rate than the normal ones.
2+
2+
the thermal decomposition process of compounds I, II, III and Co , Cu
,
The activation energy of ligand II and its Co2 , Cu , Zn and Sn
+
2+
2+
2+
Zn , Sn metal complexes are non-spontaneous, i.e., the materials are
thermally stable. The synthesized ligands in comparison to their me-
tal complexes were also screened for their antibacterial and anti-
fungal activities against some bacterial species. The activity data
show the metal complexes to be more potent antibacterials than
the parent ligands against two or more bacterial species.
2+
2+
complexes is expected to increase in relation with decrease in their
radii. The activation energies of decomposition were in the range
5
trated to the thermal stability of the complexes. The smaller size
of the ions permits a closer approach of the ligand (H pClMaTS).
ꢄ1
6.9–461 kJ mol . The high values of the activation energy illus-
4
2+
Hence, the E value in the first stage for the Zn complex is higher
than that for the other Sn2 , Cu and Co complex. The activation
+
2+
2+
Acknowledgment
energies of ligand III and its metal complexes were in the range
5
trated to the thermal stability of the complexes. It is clear that
the thermal decomposition process of compounds I, II, III and
Co , Cu , Zn , Sn metal complexes are non-spontaneous, i.e.,
the materials are thermally stable.
ꢄ1
0.2–337 kJ mol . The high values of the activation energy illus-
The Authors would like to thank Prof. Dr. A.A. El-Asmy and Dr.
M.S. Refat.
2
+
2+
2+
2+
Appendix A. Supplementary material
Provided with this paper some supporting information con-
cerned with the following topics:
3.8. Antibacterial activity
The inhibition zones of antibacterial and antifungal activities at
1. The thermal decomposition steps for ligands II, III and their
metal complexes (Tables S1 and S3).
2. The thermodynamic parameters for the ligands II, III and their
metal complexes (Tables S2 and S4).
3. The inhibition zones of antibacterial and antifungal activities at
different concentrations (Tables S5 S6 and S7).
4. Kinetic data curves for 1,1-oxalyl-, malonyl- and succinyl-bis(4-
p-chlorophenylthiosemicarbazide) ligands and the correspond-
ing metal complexes by employing the Coats–Redfern and
Horowitz–Metzger relations (Figs. S1–S15).
different concentration (1.0, 2.5 and 5.0 mg/mL) are presented in
Tables S5–S7. The data indicate that some metal complexes show
an appreciable activity against E. Coli, P. aeruginosa species and
Gram-positive bacteria;B. cereus and S. aureus. It has been observed
that Zn(II) and Sn(II) complexes have much toxicity. This is ex-
pected because the Tin and Zinc salts are mostly used as fungicides.
Such increased activity of the metal chelates can be explained on
the effect of binding of the metal complexes to DNA [47] and the
basis of the Tweedy’s chelation theory [48]. The increase in antimi-
crobial activity is due to faster diffusion of metal complexes as a
whole through the cell membrane or due to the combined activity
of the metal and ligand. Thus, according to chelation theory, the
polarity of the metal ion will be reduced to a greater extent due
to the overlap of the ligand orbital and partial sharing of positive
charge of metal ion with donor groups [49]. Further, it increases
Supplementary data associated with this article can be found, in
the online version, at doi:10.1016/j.molstruc.2011.11.024.
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