Preparation, characterization and biological activity of Fe(III), Fe(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and UO2(II) complexes of new cyclodiphosph(V)azane of sulfaguanidine

Article abstract of DOI:10.1016/j.saa.2004.12.047

Novel hexachlorocyclodiphosph(V)azane of sulfaguanidine, H₄L, l,3-[N′-amidino-sulfanilamide]-2,2,2,4,4,4-hexachlorocyclodiphosph(V) azane was prepared and its coordination behaviour towards the transition metal ions Fe(III), Fe(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and UO ₂(II) was studied. The structures of the isolated products are proposed based on elemental analyses, IR, UV-vis, ¹H NMR, mass spectra, reflectance, magnetic susceptibility measurements and thermogravimetric analysis (TGA). The hyperfine interactions in the isolated complex compounds were studied using 14.4 keV γ-ray from radioactive ⁵⁷Co (Moessbauer spectroscopy). The data show that the ligand are coordinated to the metal ions via the sulfonamide O and deprotonated NH atoms in an octahedral manner. The H₄L ligand forms complexes of the general formulae [(MX_z)₂(H₂L)H₂O)_n] and [(FeSO₄)₂ (H₄L) (H₂O)₄], where X = NO₃ in case of UO₂(II) and Cl in case of Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II). The molar conductance data show that the complexes are non-electrolytes. The thermal behaviour of the complexes was studied and different thermodynamic parameters were calculated using Coats-Redfern method. Most of the prepared complexes showed high bactericidal activity and some of the complexes show more activity compared with the ligand and standards.

Full text of DOI:10.1016/j.saa.2004.12.047

Spectrochimica Acta Part A 62 (2005) 326–334
Preparation, characterization and biological activity of Fe(III), Fe(II),
Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and UO2(II) complexes of new
cyclodiphosph(V)azane of sulfaguanidine
Carmen M. Sharaby
Chemistry Department, Faculty of Science, Al-Azhar University (Girls), Nasr City, Cairo, Egypt
Received 13 October 2004; accepted 3 December 2004
Abstract
Novel hexachlorocyclodiphosph(V)azane of sulfaguanidine, H4L, l,3-[Nꢀ-amidino-sulfanilamide]-2,2,2,4,4,4-hexachlorocyclodiphos-
ph(V)azane was prepared and its coordination behaviour towards the transition metal ions Fe(III), Fe(II), Co(II), Ni(II), Cu(II), Zn(II),
1
Cd(II) and UO2(II) was studied. The structures of the isolated products are proposed based on elemental analyses, IR, UV–vis, H NMR,
mass spectra, reflectance, magnetic susceptibility measurements and thermogravimetric analysis (TGA). The hyperfine interactions in the
isolated complex compounds were studied using 14.4 keV ␥-ray from radioactive 57Co (Mo¨ssbauer spectroscopy). The data show that the
ligand are coordinated to the metal ions via the sulfonamide O and deprotonated NH atoms in an octahedral manner. The H4L ligand forms
complexes of the general formulae [(MXz)2(H2L)H2O)n] and [(FeSO4)2 (H4L) (H2O)4], where X = NO3 in case of UO2(II) and Cl in case
of Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II). The molar conductance data show that the complexes are non-electrolytes. The thermal
behaviour of the complexes was studied and different thermodynamic parameters were calculated using Coats–Redfern method. Most of
the prepared complexes showed high bactericidal activity and some of the complexes show more activity compared with the ligand and
standards.
© 2005 Elsevier B.V. All rights reserved.
Keywords: Sulfaguanidine; Phosphorus pentachloride; Transition metal ions
1. Introduction
can be potential homogeneous or phase-transfer catalysts in
various organic transformations.
In recent years, structural feature of four-membered N2P2
ring compounds, in which the coordination number of P
varies from three to five, has attached considerable atten-
tion [1]. Heterocycles with P–C, P–N, P–O and P–S bonds,
in addition to their great biochemical and commercial impor-
tance [2], play a major role in some substitution mechanisms
as intermediates or as transition states [2,3]. Also, some P
containing heterocycles have been found to be potentially
carcinostatics [2,3] among other pharmacological activities.
The introduction of tervalent P centers in the ring enhances
the versatility of the heterocycles in complexing with both
hard and soft metals. Since the tervalent P centers can stabi-
lize transition metals in low oxidation states, such complexes
There is considerable current interest in compounds con-
taining spiro and ansaorganic P rings [4]. Although the am-
monolysis of some 1,3-diaryl-2,4-dichlorocyclodiphosph-
(V)azanes have been investigated in some detail [4], a
little is known about the interaction of hexachlorocy-
clodiphosph(V)azanes with bifunctional reagents [4]. The re-
action of bifunctional reagents with cyclodiphosph(V)azanes
can give rise in principle to four types of structures: (i)
spiro (both functional groups of reagent attached to the
same P atom); (ii) ansa (the two functional groups at-
tached to different P atoms in the same molecule); (iii)
cross-linking (each functional group attached to different cy-
clodiphosph(V)azanes rings) to give small oligomeric units
or polymers; (iv) only one functionality attached, whilst the
other remains free. Spiro, ansa and cross-linking structures
E-mail address: csharaby@hotmail.com.
1386-1425/$ – see front matter © 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.saa.2004.12.047

C.M. Sharaby / Spectrochimica Acta Part A 62 (2005) 326–334
327
of phosphazanes are now well-studied synthetically, spectro-
scopically and crystallographically [4].
(HCl gas ceased to evolve), the reaction mixture was cooled
to room temperature and the solids obtained were filtered,
then washed several times with dry benzene and dry diethyl
ether to give crystalline 1,3-di-[Nꢀ-(amidinosulfanilamide]-
2,2,2,4,4,4-hexachlorocyclodipho-sph(V)azane.
The reaction of hexachlorocyclodiphosph(V)azanes with
amino compounds, active methylene containing compounds
and bifunctional reagents have been investigated in some de-
tails[5,6]. Littleisknownabouttheinteractionofhexachloro-
cyclodiphosph(V)azanes with therapeutic sulphonamides
[5,6].
2.3. Synthesis of complexes
Sulfonamides are the oldest class of antimicrobials
and are still the drug of choice for many diseases
such as cancer and tuberculosis [7,8]. Cyclophosphamide
and its derivatives are examples of phosphorus com-
pounds, which are one of the most effective anticancer
agents with proven activity against a large variety of hu-
man cancers [9]. Also, cyclodiphosph(V)azane-sulfonamide
derivatives and their complexes have been prepared and
the obtained compounds showed remarkable antimicro-
bial activity against various species of Gram-positive
and Gram-negative bacteria [5,10]. An attempt to pre-
pare hexachlorocyclodiphosph(V)azane of sulfonamides has
been made using hexachlorocyclodiphosph(V)azane of sul-
famethoxazole [11,12]. In this work, novel hexachlorocy-
clodiphosph(V)azanes of sulfaguanidine, H4L, were pre-
pared and the behaviour of this ligand towards some tran-
sition metal ions were studied using different techniques.
Also, the bactericidal activity of these complexes was
studied.
A solution of the metal salts (10 mmol) in 50 mL
dry ethanol was added dropwise to a solution of cy-
clodiphosph(V)azane of sulfa drug (5 mmol) in 100 mL abso-
lute ethanol in a 2:1 metal to ligand molar ratio at room tem-
perature with continuous stirring. After complete addition
of the metal salt solution, the reaction mixture was heated
under reflux for about 2 h under dry conditions. The com-
plexes obtained were washed with dry ethanol then with
dry diethyl ether and dried in vacuo. The products ob-
tained give elemental analyses consistent with the proposed
structures.
2.4. Instrumentation
The microanalyses of carbon, hydrogen, nitrogen and
sulphur were carried out at the Microanalytical Center at
Cairo University. The IR spectra were recorded on a Shi-
madzu FT-IR spectrometer using KBr discs. 1H NMR spec-
tra (DMSO-d6) were recorded at room temperature, using
TMS as internal standard. The solid reflectance spectra were
measured using a Shimadzu PC 3101 spectrophotometer.
Magnetic susceptibilities of the complexes in the solid state
were recorded at room temperature on a Sherwood Sci-
entific Magnetic Susceptibility Balance using the Faraday
method. The molar conductance measurements were car-
ried out using a Sybron–Barnstead conductometer. The ther-
mogravimetric analyses (TG) were carried out on a Shi-
madzu TGA-50 H thermal analyzer. TGA was carried out
in a dynamic nitrogen atmosphere (20 mL min−1) with a
heating rate of 10 ◦C min−1. The electronic spectra of so-
lutions of the complexes in DMF (10−3M) were recorded
on a Perkin-Elmer Lambda–3B UV–vis spectraphotome-
ter. The mass spectra were performed by a Shimadzu-Ge-
MS-Qp 100 EX mass spectrometer using the direct inlet
2. Experimental
2.1. Reagents
All chemicals used in this investigation were of analar
grade, provided by B.D.H. chemicals. These include
FeCl3·6H2O, FeSO4·7H2O, CoCl2·6H2O, NiCl2·6H2O,
CuCl2·2H2O, ZnCl2, CdCl2·H2O and UO2(NO3)2·2H2O,
sulfaguanidine and phosphorus pentachloride. The solvents
used were dry ethanol, dry benzene, dry diethylether,
dimethylformamide (DMF) and deutrated dimethyl sulfox-
ide (DMSO).
2.2. Synthesis of cyclodiphosph(V)azane of
sulfaguanidine (H4L)
¨
system. Mossbauer measurements were performed in the
Physics Department, Faculty of Science, Al-Azhar Univer-
sity, at room temperature in a transmission geometry employ-
ing 57Co as a radioactive source. The spectra were analyzed
using a computer program based on Lorentzian distribution.
The isomer shifts were expressed relative to a metallic iron
absorber.
Metal contents were determined complexometrically by
standard EDTA titration [14]. The phosphorus content was
determined gravimetrically as phosphorammonium molyb-
date using the Voy method [15]. The biological activity ex-
periments were carried out at the Microbiology Laboratory
at Cairo University, Cairo, Egypt.
The H4L ligand was prepared using the methods of
Chapmann et al. [13a], and Zhnurova and Kirsanov [13b].
Sulfaguanidine [Nꢀ-amidinosulsulfanilamide] (0.1 mol,
28.60 g) in 100 mL cold dry benzene, was added in small
portions to a stirred cold solution (0.1 mol, 20.85 g) of phos-
phorus pentachloride in 100 mL cold dry benzene during
half hour at ꢁ15 ◦C. After the addition was completed, the
reaction mixture was heated under reflux for 3 h under an-
hydrous conditions with continuous stirring (the experiment
was done in a well-ventilated area because benzene is a
cancer suspect agent). After the completion of the reaction

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C.M. Sharaby / Spectrochimica Acta Part A 62 (2005) 326–334
Fig. 1. Proposed structure of H4L ligand.
3. Results and discussion
3.1. The ligand
The ligand in the present work, novel hexachloro-
cyclodiphosph(V)azane of sulfaguanidine was prepared,
using the methods of Chapmann et al. [13a], and
Zhnurova and Kirsanov [13b]. Phosphorus pentachlo-
ride was reacted in cold dry benzene with sulfaguani-
dine to give1, 3-di-[Nꢀ-amidinosulfanilamide]-2,2,2,4,4,4-
hexachloro-cyclodiphosph(V)azane (H4L) in 73% yield. The
proposed structure for the ligand is shown in Fig. 1.
The assignment of the proposed structures for H4L ligand
is based on the correct elemental analyses for C, H, N, S and
P (Table 1). The UV spectra of the ligand in DMF showed
absorption band at 267 nm, which is characteristic for phos-
phazo four-membered ring of the dimeric structure [6,16].
The infrared spectra of the H4L ligand showed the character-
istic bands for para-disubstituted benzene rings. The ν(P–N),
ν(SO2), ν(C N), ν(P–Cl) and ν(NH) values are summarized
in Table 2. The 1H NMR spectra of the ligand showed char-
acteristic proton signals, which are listed in Table 3. Broad
signals appeared at δ = 7.16, 7.37 and 5.82 ppm are character-
istic of –SO2NH, –C (NH) and NH2 proton signals, respec-
tively. Further insight concerning the structure of the ligand
was obtained from their mass spectra. The mass spectromet-
ric fragmentation pattern of H4L ligand (Scheme 1) showed
a base peak at m/z 313 (100), together with peaks at m/z 368
(98), 314(24), 213 (97) and m/z 222 (23) which confirm the
proposed structure of H4L ligand (Fig. 1).
3.2. Metal complexes
Following the successful preparation of the ligand, atten-
tion was directed towards the chemical behaviour of the lig-
and H4L towards transition metal ions. The metal ions se-
lected for this purpose were Fe(III), Fe(II), Co(II), Ni(II),
Cu(II), Zn(II), Cd(II) and UO2(II).
When a mixture of 1 mol of H4L ligand in dry ethanol was
reacted with 2 mol of the metal salts in dry ethanol, a change
in colour was observed and the complex compounds pre-
cipitated. The products were purified by washing with dry
ethanol, and gave elemental analyses compatible with the
suggested formulae given in Table 1 according to the follow-
ing general equation:
2MXz + H4L + nH2O → [(MXz)2(H2L)(H2O)n] + HX

C.M. Sharaby / Spectrochimica Acta Part A 62 (2005) 326–334
329
Table 3
1H NMR spectra of the ligand H4L and its Zn(II) and Cd(II) complexes
Compound
Chemical shift,
Assignment
δ (ppm)
7.63
6.92
5.82
7.16
7.37
–
d, 4H, ArH’s, J = 8.58 Hz
d, 4H, ArH’s, J = 8.68 Hz
br, 4H, –C (NH)(NH2)
br, 2H, -SO2NH
s, 2H, –C (NH)
br, coordinated H2O protons
H4L
7.47
6.67
4.2
6.72
–
d, 4H, ArH’s, J = 8.42 Hz
d, 4H, ArH’s, J = 8.48 Hz
br, 4H, –C (NH)(NH2)
br, 2H, -SO2NH
[(ZnCl)2(H2L)(H2O)6]
s, 2H, –C (NH)
4.0
br, coordinated H2O protons
7.65
6.93
4.9
7.08
–
d, 4H, ArH’s, J = 8.62 Hz
d, 4H, ArH’s, J = 8.62 Hz
br, 4H, –C (NH)(NH2)
br, 2H, -SO2NH
[(CdCl)2(H2L)(H2O)6]
s, 2H, –C (NH)
4.7
br, coordinated H2O protons
2FeSO4 + H4L + 4H2O → [(FeSO4)2(H4L)(H2O)4]
where M = Fe(III) (X = Cl, z = 2, n = 4); Co(II) (X = Cl, z = 1,
n = 6); Ni(II) (X = Cl, z = 1, n = 6), Cu(II) (X = Cl, z = 1, n = 6);
Zn(II) (X = Cl, z = 1, n = 6); Cd(II) (X = Cl, z = 1, n = 6) and
UO2(II) (X = NO3, z = 1, n = 2).
The analytical data of the isolated complexes are listed
in Table 1. Further, confirmation of the proposed structures
of the chelates of the cyclodiphosph(V)azane of sulfa drug
with metal salts was done using different physico-chemical
methods shown below.
3.2.1. IR spectra and mode of bonding
The infrared spectra assignment of the proposed struc-
tures of the cyclodiphosph(V)azane of sulfa drug complexes
was made through consideration of their infrared spectra. The
coordinated stretching vibration bands of the isolated prod-
ucts were assigned by using a comparison method of infrared
spectra comparing the spectra of the free ligand and its metal
complexes.
The bands that appear near 35003400 cm−1 and
3400 cm−1 are due to νasym(NH2) and νsym(NH2) vibra-
tions of the NH2 group [17]. These vibration modes ap-
pear at higher or lower wavenumbers, compared with those
of the free ligand. This may be due to that the hydro-
gen bonds involving the amino groups [17]. The bands
at 1310 cm−1 and 1032 cm−1 are attributed to asymmet-
ric and symmetric stretching vibrations, respectively, of the
sulfone group, ν(O S O), in the free ligand. These bands
are shifted to higher frequencies, at 1332–1384 cm−1 and
1036–1092 cm−1 upon coordination to the transition metals
[12].
Also, the stretching vibration mode characteristic for
ν(NH) of –C (NH)(NH2) moiety at 3160 cm−1 in the lig-

330
C.M. Sharaby / Spectrochimica Acta Part A 62 (2005) 326–334
Scheme 1. Possible fragmentation pathways of H4L ligand.
and was shifted to higher frequencies (3206–3220 cm−1) in
the complexes indicating the coordination via deprotonated
NH group. This is also supported by the shift of the ν(C N)
stretching vibration band at 1610 cm−1 in the free ligand to
1590–1536 cm−1 in the complexes.
appeared in the spectra of the isolated complexes indicat-
ing coordination via deprotonated NH atom. Also, the signal
characteristic for –NH2 group shifted to lower frequencies
due to the complexation.
3.2.4. Electronic spectra and magnetic properties
In all of the metal complexes, there are new medium
to weak bands appearing at lower frequencies between
440–480 cm−1 and 500–552 cm−1, which were assigned
to ν(M–N) and ν(M–O) stretching modes, respectively
[6,12,18,19]. These stretches were not present in the spec-
tra of the ligand.
The UV–vis spectra of complexes in DMF solution
showedabsorption bandsbetween267 nm and282 nm, which
is characteristic of phosphazo four-membered rings [20,21].
However, the absorptions were red shifted with respect to the
ligands depending on the types of metal ions present. The
spectra of the Fe(III), Fe(II) and Cu(II) complexes further
display a band in the range 365–440 nm, which might be as-
signed to charge transfer transition (most probably L → M
CT) [22]. For the Co(II) complex, however, a d–d bands are
observed at 600 nm and 675 nm which may attributed to the
The appearance of bands at 3340–3444 cm−1 and
796–832 cm−1 is due to the stretching vibration and out of
plane bending of coordinated water molecules in the spectra
of the metal complexes.
4
4
4
4
transitions T1 g (F) → T2 g (P) and T1 g (F) → A2 g (F),
respectively, typical of octahedral structure around Co(II) ion
[22].
3.2.2. Molar conductance data
The molar conductance data of the complexes (Λm = 8.37
to 17.20 ꢀ−1 mol−1 cm2) in 10−3 M DMF solution at 25 ◦C,
listed in Table 1, revealed that the complexes are non-
electrolytes.
The diffuse reflectance spectra of the complexes show
bands at 249–250 nm, which are associated with interligand
transitions.
From the diffuse reflectance spectrum of the Fe(III) com-
3.2.3. 1H NMR spectra
plex, it is observed that a band at 22,421 cm−1 may be as-
The 1H NMR spectra of the diamagnetic Zn(II) and Cd(II)
complexes showed the same characteristic proton signals for
the ligand. The signal characteristic for –C (NH) group dis-
signed to the A1 g → T2 g (G) transition in octahedral ge-
6
ometry [23]. Two bands, also, observed at 15,649 cm−1 and
17,482 cm−1 which can attribute to 6A1 g → T1 g transition.
5

C.M. Sharaby / Spectrochimica Acta Part A 62 (2005) 326–334
331
The measured magnetic moment value of 5.99 B.M. confirm
octahedral geometry involving sp3d2 hybridization in Fe(III)
ion [24].
The diffuse reflectance spectrum of Fe(II) complex dis-
plays two absorption bands at 15,174 cm−1 and 22,222 cm−1
which are assigned to 5T2 g → Eg transitions [12,25]. Also,
5
the band at 25,641 cm−1 is assigned to L → M charge trans-
fer [25]. The observed magnetic moment of 4.90 B.M. is
consistent with an octahedral geometry [25].
The electronic spectrum of the Co(II) complex displays
two bands at 15,313 cm−1 and 17,482 cm−1 assigned to the
4
4
4
4T1 g → T1 g (P) and T1 g → T2 g (F) transitions, respec-
tively, which arise due to ligand field transition of the pseudo
octahedral component of the Co(II) complex. The observed
magnetic moment value is µeff = 4.30 B.M. at room temper-
ature which confirms the octahedral structure of this cobalt
complex [12]. The band observed at 22,624 cm−1 refers to
L → M CT band.
The solid reflectance spectrum of the Ni(II) complex
shows bands at 23,255, 17,482 and 18,917 cm−1, suggest-
3
3
3
3
ing the existence of A2 g → T1 g (P), A2 g → T1 g (F)
3
3
and A2 g → T2 g transitions, respectively, with an octahe-
dral spatial configuration. The observed magnetic moment
of the complex is 2.95 B.M., which confirms the octahedral
structure of this complex [12,26].
Fig. 2. Mo¨ssbauer spectra of the iron complexes.
of 40–250 ◦C, representing the loss of two coordinated wa-
ter, 4HCl and O2 gases with a found mass loss of 20.29%
(calcd. 20.91%); the second stage is two steps within the
temperature range 250–650 ◦C, represent the decomposition
of the organic part with a found mass loss of 63.86% (calcd.
63.47%). At the end of the thermogram, the metal oxide,
Fe2O3, was the residue 15.85% (calcd. 15.62%), which is in
good agreement with the calculated metal content obtained
and the results of elemental analyses (Table 1).
The solid reflectance spectrum of the Cu(II) complex gave
abandat16,806 cm−1, whichmaybeassignedto2Eg → T2 g
2
[27]. The observed magnetic moment of the Cu(II) complex
is 1.85 B.M., which confirms the octahedral structure of this
complex. The band observed at 22,935 cm−1 refers to L → M
CT band.
TheZn(II), Cd(II)andUO2(II)complexesarediamagnetic
and in analogous to similar previously published data [12],
they proposed to have octahedral structure.
The thermogram of the Co(II) complex shows that the
first and second weight losses are between 50 ◦C and 220 ◦C
which represent the loss of five coordinated water molecules
and 2HCl and 1/2O2 gases with a found mass loss of
18.65% (calcd. 18.01%). The energy of activation (Table 5)
is amounted to 44.53 kJ mol−1 and 89.48 kJ mol−1 for the
first and second steps, respectively. The third, fourth and fifth
steps:withinthetemperaturerange220–950 ◦C, representthe
decomposition of the organic part with a found mass loss of
65.80% (calcd. 65.30%) leaving behind Co2O3 as the prod-
uct of decomposition. The energy of activation of the third,
fourth and fifth steps respectively is amounted to 146.1, 115.2
3.2.5. Mo¨ssbauer measurements
¨
The Mossbauer spectra were measured at room tem-
perature for iron complexes. The spectra revealded
the presence of Fe ions in [(FeCl2)2(H2L)(H2O)4] and
[FeSO4)(H4L)(H2O)4] in ferric and ferrous state respectively
¨
in octahedral coordination [28]. The Mossbauer parameters
are listed in Table 5 and Fig. 2.
4. Thermal studies
and 92.31 kJ mol−1
.
The Ni(II) complex shows four steps of decomposition
within the temperature range 40–750 ◦C. The first weight loss
within the temperature range 40–210 ◦C represents the loss
Thermogravimetric studies (TGA) for the complexes were
carried out within the temperature range from room temper-
ature up to 1000 ◦C. The estimated mass losses were com-
puted based onTGresultsand the calculated masslosseswere
computed using the results of microanalyses (Table 4). The
determined temperature ranges and percent losses in mass of
the solid complexes on heating are given in Table 4, which
revealed the following findings.
Table 4
Mo¨ssbauer parameters for iron complexes of the H4L ligand
Complex compound
Isomer shift
(IS) (mm/s)
Quadrupole splitting
(QS) (mm/s)
[(FeCl2)2(H2L)(H2O)4]
[FeSO4)2(H4L)(H2O4)]
0.42
1.6
0.72
3.6
The Fe(III) complex gives a decomposition pattern as fol-
lows: the first stage is two steps within the temperature range

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C.M. Sharaby / Spectrochimica Acta Part A 62 (2005) 326–334
Table 5
Thermogravimetric data of the ligand H4L metal complexes
Complex
TG range (◦C)
DTGmax (◦C)
% Found (Calcd.)
Assignment
Metallic residue
Fe2O3
Mass loss
Total mass loss
84.15 (84.38)
84.45 (83.31)
84.34 (84.97)
61.99 (61.35)
[(FeCl2)2(H2L)(H2O)4]
40–250
70, 178
20.29 (20.91)
Loss of two coordinate H2O,
4HCl and O2
Loss of C14H14Cl6N8OP2S2
250–650
50–220
365, 520
89, 150
63.86 (63.47)
18.65 (18.01)
[(CoCl)2(H2L)(H2O)6]
[(NiCl)2(H2L)(H2O)6]
Loss of five coordinate H2O,
2HCl, and 1/2O2
Loss of C14H14Cl6N8OP2S2
Co2O3
2NiO
2UO2
220–950
40–210
270, 330, 730
87
65.80 (65.30)
17.89 (18.02)
Loss of five coordinate H2O,
2HCl, and 1/2O2
Loss of C14H14Cl6N8O2P2S2
210–750
130–260
360, 440, 580
211
66.45 (66.95)
6.99 (7.02)
[(UO2)2(H2L)(NO3)2(H2O)2]
Loss of two coordinate H2O,
NO2 and 1/2O2
Loss of NO2, 1/2O2 and
260–800
310,361,635
55.00 (54.33)
C
14H14Cl6N8O4S2P2
of 2HCl, five coordinate water and 1/2O2 gases with a found
mass loss of 17.89% (calcd. 18.02%). The activation ener-
gies of this step is amounted to 24.63 kJ mol−1. The three
remaining steps within the temperature range 210–750 ◦C
may attributed to the decomposition of C14H14Cl6N8O2P2S2
molecule with a found mass loss of 66.45% (calcd. 66.95%)
leaving behind 2NiO as the product of decomposition. The
activation energies of these steps are 67.69, 56.22 and
155.2 kJ mol−1 for the second, third and fourth steps, respec-
tively.
The UO2(II) complex is thermally decomposed in four
steps. The first step corresponds to a mass loss of 6.99%
(calcd. 7.02%) within the temperature range 130–260 ◦C rep-
resents the loss of two coordinated water, NO2 and 1/2O2
gases. The remaining steps; within the temperature range
from 260–800 ◦C, with a found mass loss of 55.0% (calcd.
54.33%)isreasonablyaccountedforthedecompositionofthe
organic part of the complex, 1/2O2 and NO2 molecules leav-
ing 2UO2 residue with a found mass loss of 38.01% (calcd.
38.65%).
Fig. 3. Suggested structural formulae of H4L metal complexes.

C.M. Sharaby / Spectrochimica Acta Part A 62 (2005) 326–334
333
Table 6
Thermodynamic data of the thermal decomposition of the complexes
Complex
TG range (◦C)
E* (kJ mol−1
)
A (S−1
)
ꢁS* (J K−1 mol−1
)
ꢁH* (kJ mol−1
)
ꢁG* (kJ mol−1
)
[(FeCl2)2(H2L)(H2O)4]
40–120
120–250
250–410
410–650
56.72
92.17
102.5
46.75
4.17 × 108
−33.15
−72.82
35.25
66.75
53.63
106.3
55.02
76.22
66.35
96.53
2.54 × 106
1.94 × 109 −105.3
6.04 × 105
−68.75
−33.05
−63.06
−97.83
[(CoCl)2(H2L)(H2O)6]
50–120
120–220
220–300
300–400
400–950
44.53
89.48
146.1
115.2
92.31
2.13 × 106
1.87 × 105
3.61 × 109
68.15
79.75
112.5
105.6
53.64
54.73
59.13
112.4
84.58
126.3
4.08 × 1010 −66.35
5.32 × 106
−76.49
−29.23
−46.55
−76.43
[(NiCl)2(H2L)(H2O)6]
40–210
210–3900
390–500
500–750
24.63
67.69
56.22
155.2
2.62 × 109
3.09 × 107
6.53 × 109
56.32
125.3
189.6
137.9
68.16
57.30
105.6
95.28
4.83 × 1011 −77.29
[(UO2)2(H2L)(NO3)2(H2O)2]
130–260
260–330
330–400
400–800
33.65
60.28
117.3
72.80
3.05 × 107
−73.18
47.26
76.29
26.77
135.1
38.29
101.6
69.52
64.95
4.58 × 1012 −68.07
1.99 × 107 −112.2
3.52 × 1010 −83.62
From the above thermogravimetric analyses, the overall
weight losses for the Fe(III), Co(II), Ni(II) and UO2(II) com-
plexes agree well with the proposed formulae obtained by
elemental analyses, IR, 1H NMR, solid reflectance and mag-
where Wf is the mass loss at the completion of the reaction,
W is the mass loss up to temperature T, R is the gas constant,
E is the activation energy in kJ mol−1, θ is the heating rate
*
∼
and (1 − (2RT/E )) 1. A plot of the left-hand side of Eq.
=
¨
netic susceptibility and Mossbauer measurements.
(1) against 1/T gives a slope from which E* was calculated
and A (Arrhenius constant) was determined from the inter-
cept. The entropy of activation (ꢁS*), enthalpy of activation
(ꢁH*) and the free energy change of activation ((ꢁG*) were
calculated (Table 5). According to the kinetic data obtained
from DTG curves, all the complexes have negative entropy,
which indicates that activated complexes have more ordered
systems than reactants.
5. Kinetic studies
The kinetic parameters such as activation energy (E*), en-
thalpy (ꢁH*), entropy (ꢁS*) and free energy change of the
decomposition (ꢁG*) were evaluated graphically by employ-
ing the Coats–Redfern relation [29]:
6. Structural interpretation
ꢀ
ꢁ
2RT
E∗
log{Wf/(Wf − W)}
log
From the above findings, we propose that the coor-
dination occurs through the deprotonated nitrogen of the
–C NH(NH2) moiety and the oxygen of the –SO2NH group
to give the following structures (Fig. 3).
T2
ꢀ
ꢂ
ꢃꢁ
AR
θE∗
E∗
= log
1 −
−
(1)
2.303RT
Table 7
Antibacterial activity of H4L and its metal complexes
Compound
Staphylococcus Pyogenes
Pseudomonas aeruginosa
Escherichia coli
Fungus(Candida)
5 mg/L 2.5 mg/L 1 mg/L
5 mg/L 2.5 mg/L 1 mg/L
5 mg/L 2.5 mg/L 1 mg/L 5 mg/L 2.5 mg/L 1 mg/L
H4L
+++
++
++
+++
++
+++
+++
++
++
+
+
++
++
++
++
++
++
+
+
+
+
+
+
++
+
+
++
−
−
−
+
+
+
++
−
+
++
+
++
+
++
+++
+
+
−
+
+
−
−
+
−
−
+
−
−
−
−
−
−
−
−
−
−
−
−
[(FeCl2)2(H2L)(H2O)4]
[(FeSO4)2(H4L)(H2O)4]
[(CoCl)2(H2L)(H2O)6]
[(NiCl)2(H2L)(H2O)6]
[(CuCl)2(H2L)(H2O)6]
[(ZnCl)2(H2L)(H2O)6]
[(CdCl)2(H2L)(H2O)6]
−
−
++
++
++
++
++
+
+
++
+++
++
++
++
+
+
++
+
−
++
−
+
++
−
−
+
+
−
+
+
+
+
++
++
−
−
−
[(UO2)2(H2L)(NO3)2(H2O)2] ++
+
++
+
+
+
Tavanica
Tarivida
+++
++
++
+
+
−
+++
++
++
+
+
−
+++
++
++
+
+
−
−
−
−
−
−
−
Inhibition values: 0.1–0.5 cm beyond control = +; inhibition values: 0.6–1.0 cm beyond control = ++; inhibition values: 1.1–1.5 cm beyond control = +++.
a
Standard materials.

334
C.M. Sharaby / Spectrochimica Acta Part A 62 (2005) 326–334
[10] C. Sharaby, Al-Azhar Bull. Sci. 8 (1) (1997) 29–44.
7. Antimicrobial activity
[11] C. Sharaby, Ph.D. Thesis, Faculty of Science, Al-Azhar University
(Girls), Cairo, Egypt 1992.
[12] C. Sharaby, Synth. React. Inorg. Met. Org. Chem., in press.
[13] (a) A.C. Chapmann, N.L. Paddock, H.T. Searle, J. Chem. Soc. (1961)
1825–1827;
(b) I.N. Zhnurova, A.V. Kirsanov, Zh. Obshch. Khim. 32 (1962)
2576–2580.
[14] G. Schwarzenbach, Complexometric Titrations, first ed., Interscience
Publishers, London/New York, 1957, pp. 77–85.
[15] R. Voy, Chem. Ztg. Chem. Apparatus 21 (1897) 941.
[16] I.M. Abd-Ellah, E.H.M. Ibrahim, A.N. El-Khazandar, J. Phosphorous
Sulfur 29 (1987) 239–248.
[17] A.G. Raso, J.J. Fiol, S. Rigo, A.L. Lopez, E. Molins, E. Espinosa, E.
Borras, G. Alzuet, J. Borras, A. Castineiras, Polyhedron 19 (2000)
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Antifungal and antibacterial activities of the ligand H4L
and its metal complexes were studied against Candida, as a
fungus E. coli, Pseudomans aeruginosa as gram-negative and
Staphylococcus pyogenes as gram-positive bacteria at differ-
ent concentrations of 1, 2.5 and 5 mg/mL in DMF as solvent
by single disc method [30,31] using Tavanic and Tarivid as
standard materials (Table 6).
From the antimicrobial results (Table 6), it is clear that the
prepared ligand H4L showed in some cases a higher activity
than the tested standard. On the other hand, the prepared
complexes in some cases demonstrated a significant higher
antimicrobial activity than both the ligand and the standards
(Table 7).
[18] M.A. El-Ries, S.M. Abu-El-Wafa, F.A. Aly, Egypt. J. Pharm. Sci.
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[19] J.R. Ferraro, Low Frequency Vibrations of Inorganic and Coordi-
nation Compounds, first ed., Plenum Press, New York, 1971, pp.
168–196.
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