Spectroscopic, thermal and biocidal studies on Mn(II), Co(II), Ni(II) and Cu(II) complexes of tridentate ligand having semicarbazone moieties

Article abstract of DOI:10.1007/s10973-009-0397-5

Mn(II), Co(II), Ni(II) and Cu(II) complexes having the general composition M(L)₂X₂ [where L = 2-pyridinecarboxaldehyde semicarbazone, M = Mn(II), Co(II), Ni(II) and Cu(II), X = Cl^- and NO₃ ^-] have been synthesized. All the synthesized compounds were identified and confirmed by elemental analysis, molar conductance, magnetic susceptibility measurements, mass, IR, EPR, electronic spectral studies and thermogravimetric analysis (TG). The Molar conductance measurements of the complexes lie in the range 209-228 Ω¹ cm^-1 mol ^-1 indicating that the complexes are 1:2 electrolytic in nature. Thus the complexes may be formulated as [M(L)₂]X₂. The magnetic moment measurements of the complexes indicate that all the complexes are in high-spin state. On the basis of spectral studies an octahedral geometry has been assigned for Mn(II), Co(II) and Ni(II) complexes whereas tetragonal geometry for Cu(II) complexes. The thermal studies suggested that the complexes are more stable compared with free ligand. This fact was supported by calculating the thermodynamic parameters by using Horowitz-Metzger (HM) and Coats-Redfern (CR) equations. The free ligand and its metal complexes were also evaluated against the growth of phytopathogenic fungi and bacteria in vitro.

Full text of DOI:10.1007/s10973-009-0397-5

J Therm Anal Calorim (2010) 100:261–267
DOI 10.1007/s10973-009-0397-5
Spectroscopic, thermal and biocidal studies on Mn(II), Co(II),
Ni(II) and Cu(II) complexes of tridentate ligand having
semicarbazone moieties
Moamen S. Refat Æ Sulekh Chandra Æ
Monika Tyagi
Received: 12 March 2009 / Accepted: 29 July 2009 / Published online: 28 August 2009
´
´
Ó Akademiai Kiado, Budapest, Hungary 2009
Abstract Mn(II), Co(II), Ni(II) and Cu(II) complexes
having the general composition M(L)2X2 [where L =
2-pyridinecarboxaldehyde semicarbazone, M = Mn(II),
Co(II), Ni(II) and Cu(II), X = Cl- and NO3-] have been
synthesized. All the synthesized compounds were identi-
fied and confirmed by elemental analysis, molar conduc-
tance, magnetic susceptibility measurements, mass, IR,
EPR, electronic spectral studies and thermogravimetric
analysis (TG). The Molar conductance measurements of
the complexes lie in the range 209–228 X1 cm-1 mol-1
indicating that the complexes are 1:2 electrolytic in nature.
Thus the complexes may be formulated as [M(L)2]X2. The
magnetic moment measurements of the complexes indicate
that all the complexes are in high-spin state. On the basis of
spectral studies an octahedral geometry has been assigned
for Mn(II), Co(II) and Ni(II) complexes whereas tetragonal
geometry for Cu(II) complexes. The thermal studies sug-
gested that the complexes are more stable compared with
free ligand. This fact was supported by calculating the
thermodynamic parameters by using Horowitz–Metzger
(HM) and Coats–Redfern (CR) equations. The free ligand
and its metal complexes were also evaluated against the
growth of phytopathogenic fungi and bacteria in vitro.
Keywords Biological activity ꢀ 3d Metals ꢀ
Semicarbazone ꢀ Spectroscopic ꢀ Thermal
Introduction
Semicarbazones, as well as their sulphur analogs, thio-
semicarbazones, are compounds possessing a wide variety of
biological applications. The formation of a variety of metal
complexes from these ligands speaks for their spectacular
progress in coordination and bioinorganic chemistry [1].
Semicarbazones are reported to possess versatile structural
features and very good antifungal, antibacterial, antitry-
panosomal and anticonvulsant properties [2–6]. Spectral
studies of semicarbazones of furaldehyde, salicylaldehyde,
2-hydoxyacetophenone, 4-formylpyridine and 4 acetylpyri-
dine were also reported [7–9]. Rhenium(V) and Ruthe-
nium(II) complexes of 5-nitrofurylsemicarbazone were
tested against the trypanocidal activity [10]. Ni(II) com-
plexes of thiosemicarbazones and semicarbazones were
tested against the antimicrobial activity in vitro [11]. Keep-
ing the above view in mind, we reported the synthesis,
spectroscopic, thermal and biocidal studiesof Mn(II), Co(II),
Ni(II) and Cu(II) complexes with biologically relevant
ligand. The structure of ligand and scheme for the synthesis
is shown in Fig. 1.
S. Chandra ꢀ M. Tyagi
Department of Chemistry, Zakir Husain College
(University of Delhi), JLN-Marg,
New Delhi 110 002, India
M. S. Refat
Department of Chemistry, Faculty of Science,
Port-Said, Suez Canal University, Port-Said, Egypt
Experimental
All the chemicals used were of Anala R grade and
received from Sigma-Aldrich and Fluka companies. Metal
salts were purchased from E. Merck and were used as
received.
M. S. Refat (&)
Department of Chemistry, Faculty of Science,
Taif University, Taif, Kingdom of Saudi Arabia
e-mail: msrefat@yahoo.com
123

262
M. S. Refat et al.
ꢁ
ꢂ
Reflux
CH3COONa
H
N
MX ꢀ nH O þ 2 Ligand
MðLigandÞ2 X2 þ nH2O
ꢀꢀꢀꢀ!
2
2
.
NH NHCONH HCl
2 2
70ꢁ80 ꢂ
C
C
H
O
+
N
C
H
N
C
O
NH2
N
The molar conductance (Table 1) of the complexes in
DMSO lies in the range 209–228 X-1 cm2 mol-1 indicating
that the complexes are 1:2 electrolytic in nature [12]. Thus
they may be formulated as [M(L)2]X2 [where M = Co(II),
Ni(II), Cu(II), X = Cl-, NO3-].
Fig. 1 Synthesis and structure of ligand (L)
Synthesis of ligand
An aqueous solution of semicarbazide hydrochloride
(2.22 g, 0.02 mol) and 2-pyridinecarboxaldehyde (1.9 mL,
0.02 mol) were mixed in the presence of sodium acetate
(2.72 g, 0.02 mol). This solution was stirred vigorously
with the help of mechanical stirrer for an hour. On cooling
a white product was formed, filtered, washed with cold
EtOH and dried under vacuum over P4O10.
Mass spectrum
The electronic impact mass spectrum of the ligand shows a
molecular ion (M?) peak at m/z = 165 amu corresponding
to species [C7H8N4O]?, which confirms the proposed for-
mula. It also shows series of peaks like 16, 44, 59, 78, 86,
91, 105, 130 and 158 amu correspond to various fragments.
Their intensities give the idea of the stabilities of the
fragments.
Synthesis of complexes
Hot ethanolic solution (20 mL) of corresponding metal
salts (0.01 mol) was mixed with hot ethanolic solution of
the respective ligand (0.01 mol). This solution was refluxed
for 4–5 h at 70–80 °C .On cooling a colored complex was
separated out. It was filtered, washed and re-crystallized
with ethanol and dried under vacuum over P4O10. The
purity of the complexes was checked by thin layer chro-
matography (TLC). TLC analysis was performed on silica
gel (Fluka F60 254 20 9 20; 0.2 mm) using the solvent
system n-heptane/acetone (2:1) as eluent.
Infrared spectra
A band appeared at *1,588 cm-1 in the IR spectrum of
the ligand is due to the m(C=N) group. On complex for-
mation, this band is shifted towards lower side [13]. The
pyridine ring vibration at *624 cm-1 in the free ligand is
also shifted toward higher frequency [14]. This indicates
that the nitrogen atom of the pyridine ring is involved in
coordination. The m(C=O) vibration appeared at
*1,689 cm-1 in the ligand is shifted towards lower side on
complexation [15]. Thus it has been concluded that ligand
act as tridentate coordinate through the pyridine N, imine N
and Oxygen atom. In the IR spectra of the nitrate com-
plexes of Mn(II), Co(II), Ni(II) and Cu(II) show a broad
band at 1,376–1,396 cm-1 corresponding to uncoordinated
nitrate group [16].
Physical measurements
The C, H and N were analyzed on Carlo-Erba 1106 elemental
analyzer. The Nitrogen content of the complexes was deter-
mined using Kjeldahl’s method. Molar conductance was
measured on the ELICO (CM82T) conductivity bridge.
Magnetic susceptibility was measured at room temperature
using CuSO4ꢀ5H2O as callibrant. Electronic impact mass
spectrum was recorded on Jeol, JMS-DX-303 mass spec-
trometer. IR spectra (KBr) were recorded on FTIR spectrum
BX-II spectrophotometer. The electronic spectra were recor-
ded in DMSO on Shimadzu UV mini-1240 spectrophotom-
eter. EPR spectra of the complexes were recorded as
polycrystalline sample and in the DMSO solution, at liquid
nitrogen temperature for Co(II), and at room temperature for
the Mn(II) and Cu(II) complexes on E4-EPR spectrometer
using the DPPH as the g-marker.
Magnetic moments and (electronic and EPR) spectra
Manganese(II) complexes
The magnetic moment recorded at room temperature lies at
5.91–5.97 B.M. corresponding to five unpaired electrons.
Electronic spectra of Mn(II) complexes display four weak
intensity absorption bands in the range 18,621–18,650,
24,630–24,632, 28,540–28,750 and 30,769–31,250 cm-1
.
These bands may be assigned to the A1g ? T1g(4G),
6
4
4
4
6
4
6A1g ? Eg, A1g (4G) (10B ? 5C), A1g ? Eg (4D)
(17B ? 5C) and 6A1g ? T1g (4P) (7B ? 7C) respectively
4
Results and discussion
[17] transitions. The position of these bands suggest an
octahedral geometry around the Mn(II) ion (Fig. 2). The
EPR spectra of Mn(II) complexes were recorded at room
temperature as polycrystalline samples and in DMSO
The metal ion and ligand was condensed in the ratio of 1:2
for the preparation of mononuclear complexes. The reac-
tion sequence is given below
123

Spectroscopic, thermal and biocidal studies on Mn(II), Co(II), Ni(II) and Cu(II) complexes
263
Table 1 Molar conductance and elemental analysis data of the complexes
Compounds
Molar
Conductance/
X-1 cm2 mol-1
Color
Yield/ m.p./ Mwt Elemental analysis found (calcd.)/%
%
°C
M
C
H
N
)
C7H8N4O (L)
–
White
65
137
280
164
–
51.29 (51.22) 4.82 (4.88) 34.18 (34.14)
[Mn(L)2]Cl2
MnC14H16N8O2Cl2
225
Off White 62
454 12.15 (12.11) 37.05 (37.00) 3.49 (3.52) 24.61 (24.67)
507 10.80 (10.84) 33.18 (33.13) 3.19 (3.15) 27.67 (27.61)
458 12.82 (12.86) 36.62 (36.68) 3.55 (3.49) 24.52 (24.45)
511 11.58 (11.52) 32.92 (32.87) 3.17 (3.13) 27.42 (27.39)
458 12.76 (12.81) 36.65 (36.68) 3.52 (3.49) 24.50 (24.45)
511 11.52 (11.48) 32.90 (32.87) 3.19 (3.13) 27.36 (27.39)
463 13.87 (13.82) 36.25 (36.28) 3.52 (3.45) 24.22 (24.19)
516 12.36 (12.40) 32.59 (32.55) 3.17 (3.10) 27.18 (27.13)
[Mn(L)2](NO3)2
MnC14H16N10O8
220
218
214
222
228
209
212
Off White 64
286
220
235
256
284
185
187
[Co(L)2]Cl2
CoC14H16N8O2Cl2
Pink
60
[Co(L)2](NO3)2
CoC14H16N10O8
Shiny Pink 58
[Ni(L)2]Cl2
NiC14H16N8O2Cl2
Light
Green
Bluish
Green
Light green 69
62
[Ni(L)2](NO3)2
NiC14H16N10O8
64
[Cu(L)2]Cl2
CuC14H16N8O2Cl2
[Cu(L)2](NO3)2
CuC14H16N10O8
Shiny
green
65
temperature. The ‘g’ values are found to be almost same in
both cases in polycrystalline sample as well as in the solu-
tion. This indicates that the complexes have same geometry
in solid form as well as in the solution.
H
N
M
N
C
O
H2N
C
O
C
N
H
N
N
X2
H
Nickel(II) complexes
N
C
NH2
H
At room temperature the magnetic moments of the Ni(II)
complexes lie in the range 2.85–2.92 B.M., corresponding
to two unpaired electrons. The electronic spectra of Ni(II)
complexes display three absorption bands in the range
Fig. 2 Suggested structure of the complexes where M = Mn(II),
Co(II), Ni(II), Cu(II) and X = Cl- and NO3
10,823–12,670, 14,326–15,420 and 23,570–24,436 cm-1
.
-
The ground state of Ni(II) in an octahedral coordination
3
[18] is A2g. Thus, these bands may be assigned to three
solution. The polycrystalline spectra give an isotropic
signal centered at 1.96–2.07 (A0 = 109–112). The spectra
recorded in DMSO solution gives well resolved six line
spectra due to the hyperfine interaction between the
unpaired electrons with the 55Mn nuclear (l = 5/2).
3
3
3
spin allowed transitions A2g (F) ? T2g (F) (m1), A2g
3
3
(F) ? 3T1g (F) (m2) and A2g (F) ? T1g (P) (m3), respec-
tively. The position of these bands indicates that the
complexes have an octahedral geometry around the Ni(II)
complexes.
Cobalt(II) complexes
Copper(II) complexes
At room temperature Co(II) complexes show magnetic
moment in the range 4.85–4.90 B.M. The electronic spectra
of Co(II) complexes, recorded in DMSO solution, exhibit
absorption in the region, 10,718–11,223, 14,696–15,240,
and 18,057–18,416 cm-1. These bands may be assigned to
4T1g (F) ? T2g (F), 4T1g ? A2g and 4T1g (F) ? T1g (P)
transitions respectively. The position of these bands suggests
an octahedral environment around the Co(II) ion. The EPR
spectra of Co(II) complexes were recorded as polycrystalline
sample and in DMSO solutions at liquid nitrogen
ThemagneticmomentsofCu(II)complexeswererecorded at
room temperature. The complexes show magnetic moments
in the range 1.83–1.89 BM corresponding to one unpaired
electron. The electronic spectra of these complexes display
bands in the range 10,430–10,542, 14,792–15,432 and
25,316–25,510 cm-1. These bands correspond to the transi-
4
4
4
2
2
2
2
tions B1g ? A1g (dx2-y2 ? dz2), B1g ? B2g(dx2-y2
2
2
? dzy) and B1g ? Eg(dx2-y2 ? dzy dyz) respectively.
Therefore, the complexes may be considered to possess a
123

264
M. S. Refat et al.
tetragonal geometry [19]. EPR spectra of the Cu(II) com-
plexes were recorded, at room temperature as polycrystalline
samples, on the X-band at 9.1 GHz under the magnetic field
analysis (TG and DTG), has been successfully employed
for the study of the energetic of interactions of metal cat-
ions with biological species, such as amino acids [21]. The
weight loss profiles are analyzed the amount or percent of
weight loss at any given temperature, and the temperature
ranges of the degradation process were determined. Ther-
mal stability domains, melting points, decomposition
phenomena and their assignments for the 2-pyridine-
carboxaldehyde semicarbazone complexes are summarized
in Table 2. The simultaneous TG–DTG curves of: 2-pyri-
dinecarboxaldehyde semicarbazide (Ligand; L), [Cu(L)2]
Cl2, [Cu(L)2](NO3)2, [Co(L)2]Cl2 [Co(L)2](NO3)2, [Ni(L)2]
Cl2, [Ni(L)2](NO3)2, [Mn(L)2]Cl2 and [Mn(L)2](NO3)2
compounds at the heating rate of 10 °C/min in the static
nitrogen atmosphere are given in Fig. 3. The overall loss of
mass from the TG curves is 100% for 2-pyridinecarbox-
aldehyde semicarbazone, 83.12% for [Cu(L)2]Cl2, 84.93%
for [Cu(L)2](NO3)2, 83.66% for [Co(L)2]Cl2, 85.23% for
[Co(L)2](NO3)2, 83.42% for [Ni(L)2]Cl2, 85.76% for
[Ni(L)2](NO3)2, 80.12% for [Mn(L)2]Cl2, and 82.52%
for [Mn(L)2](NO3)2 compounds, respectively. All the
complexes have two essential maxima peaks mass loss.
The first sharp endothermic peak concerning metal(II)
chlorides Cu(II), Co(II), Ni(II) and Mn(II)) of 2-pyridine-
carboxaldehyde semicarbazone complexes: occurring
between 20 and 302 °C may be due to loss of hydrazine
molecule (N2H2) and the second decomposition step in the
range of 214–800 °C, correspond to the pyrolysis of the
2-pyridinecarboxaldehyde semicarbazone rest.
range3,000 G.Theanalysisofspectragiveg 2.0842–2.0972
k
and g\ 2.0145–2.0365. The trend g [ g\ [ 2.0023,
k
observed for the complexes, under study, indicate that the
unpairedelectronislocalizedinthedx2-y2orbitaloftheCu(II)
ion and the spectral features are characteristic for the axial
symmetry. Tetragonally elongated geometry is thus con-
firmed fortheaforesaid complexes. G = (g - 2)/(g\ - 2),
k
which measure the exchange interaction between the metal
centers in a polycrystalline solid has been calculated.
According to Hathaway [20], if G [ 4 the exchange interac-
tion is negligible, but G \ 4 indicates considerable exchange
interactioninthesolidcomplexes.Thecomplexesreportedin
thispaper givesthe‘G’valuein therange\4, whichindicates
exchange interaction in the solid complexes.
Thermal studies
2-Pyridinecarboxaldehyde semicarbazone and its metal
complexes were studied by thermogravimetric analysis
from ambient temperature to 800 °C in nitrogen atmo-
sphere. The TG curves were redrawn as % mass loss versus
temperature (TG) curves. Typical TG curves are presented
in Fig. 3 and the temperature ranges and percentage mass
losses of the decomposition reaction are given in Table 2,
together with evolved moiety and the theoretical percentage
mass losses. Thermal techniques, such as thermogravimetric
Fig. 3 TG curves of:
a [Mn(L)2]Cl2,
b [Mn(L)2](NO3)2,
c [Co(L)2]Cl2,
d [Co(L)2](NO3)2,
e [Ni(L)2]Cl2, f [Ni(L)2](NO3)2,
g [Cu(L)2]Cl2 and
h [Cu(L)2](NO3)2 complexes
100
80
60
40
20
0
100
100
A
B
C
80
80
60
40
20
60
40
20
0
200
400
600
800
0
200
400
600
800
0
200
400
600
800
Temperature/°C
Temperature/°C
Temperature/°C
100
80
60
40
20
0
100
80
60
40
20
0
100
80
60
40
20
0
D
E
F
0
200
400
600
800
0
200
400
600
800
0
200
400
600
800
Temperature/°C
Temperature/°C
Temperature/°C
100
100
80
60
40
20
H
G
80
60
40
20
0
0
0
200
400
600
800
0
200
400
600
800
Temperature/°C
Temperature/°C
123

Spectroscopic, thermal and biocidal studies on Mn(II), Co(II), Ni(II) and Cu(II) complexes
265
Table 2 Thermoanalytical results (TG and DTG) for the ligand and its complexes
Compounds
Steps
Temperature
range/°C
DTGmax
°C
/
TG mass loss/%
Assignments
Calc.
Found
C7H8N4O (L)
1st
20–480
480–800
20–302
143
581
281
438
52.44
47.56
7.05
52.06
47.94
7.04
–C2H4N3O (organic moiety)
C5H4N (pyridine ring)
2nd
1st
[Mn(L)2]Cl2 MnC14H16N8O2Cl2
–H4N2 (hydrazine molecule)
2nd
302–800
73.79
19.16
17.36
65.49
17.15
6.99
73.08
19.88
17.74
64.78
17.48
6.41
C
14H12N6Cl2 (organic moiety)
MnO2 (residue)
–C2H4N2O2 (2 amido group)
12H12N8O4 (organic moiety)
[Mn(L)2](NO3)2 MnC14H16N10O8
[Co(L)2]Cl2 CoC14H16N8O2Cl2
[Co(L)2](NO3)2 CoC14H16N10O8
[Ni(L)2]Cl2 NiC14H16N8O2Cl2
[Ni(L)2](NO3)2 NiC14H16N10O8
[Cu(L)2]Cl2 CuC14H16N8O2Cl2
[Cu(L)2](NO3)2 CuC14H16N10O8
1st
20–425
292
477
2nd
425–800
C
MnO2 (residue)
1st
20–251
225
318
–H4N2 (hydrazine molecule)
2nd
251–800
76.64
16.37
17.23
68.10
14.67
7.00
77.25
16.34
17.88
67.35
14.77
6.44
C14H12N6OCl2 (organic moiety)
CoO (residue)
1st
20–316
238
393
–C2H4N2O2 (2 amido group)
2nd
316–800
C12H12N8O5 (organic moiety)
CoO (residue)
1st
20–214
125
403
–H4N2 (hydrazine molecule)
2nd
214–800
76.68
16.32
17.24
68.13
14.63
6.92
76.98
16.58
17.40
68.36
14.24
6.64
C14H12N6OCl2 (organic moiety)
NiO (residue)
1st
20–318
267
387
–C2H4N2O2 (2 amido group)
2nd
318–800
C12H12N8O5 (organic moiety)
NiO (residue)
1st
20–300
190
488
–H4N2 (hydrazine molecule)
2nd
300–800
75.88
17.20
17.07
67.50
15.43
76.48
16.88
17.53
67.40
15.07
C14H12N6OCl2 (organic moiety)
CuO (residue)
1st
20–212
188
418
–C2H4N2O2 (2 amido group)
2nd
212–800
C12H12N8O5 (organic moiety)
CuO (residue)
slop and A in (s-1) from the intercept. The entropy of
activation DS* in (JK-1 mol-1) was calculated by using
the equation (Table 3)
Kinetic calculations
The main kinetic parameters such as activation energy
(E*), enthalpy (H*), entropy (S*) and free energy change
of the decomposition (G*) were determined graphically by
using the Coats–Redfern relation [22].
DSꢃ ¼ R lnðAh=kTsÞ
ð3Þ
where k is the Boltzmann constant, h is the Plank’s con-
stant and Ts is the DTG peak temperature.
The Coats–Redfern equation (1), which is a typical
integral method, can be represented as
Taking the activation energy of the first step as a cri-
terion, the following stability sequence can be observed in
2-pyridinecarboxaldehyde semicarbazone complexes:
[Mn(L)2]Cl2 [ [Mn(L)2](NO3)2 [ [Ni(L)2]Cl2 [ [Ni(L)2]
(NO3)2 [ [Cu(L)2]Cl2 [ [Cu(L)2](NO3)2 [ [Co(L)2]Cl2 [
[Co(L)2](NO3)2. This order of stability points to the
dependence of decomposition of the metal cations and the
ionic radius. The activation energy of Cu2?, Co2?, Ni2?
and Mn2? complexes is expected increase in relation with
decrease in their radius. The entropy in all complexes has a
negative value, this meaning that the complexes have more
ordered systems than reactants.
1
T2
Z
Z
ꢃ
n
da=ð1 ꢁ aÞ ¼ ðA=/Þ
e
ꢁE =RT dt
ð1Þ
T1
0
For convenience of integration, the lower limit T1 is usually
taken as zero. This equation on integration gives (Eq. 2);
ꢁ
ꢃ
ꢂ
Ln ꢁ lnð1 ꢁ aÞ T2 ¼ ꢁEꢃ=RT þ ln ½AR=/Eꢄ:
ð2Þ
A plot of left-hand side (LHS) against 1/T was drawn. E* is
the energy of activation in kJmol-1 and calculated from the
123

266
M. S. Refat et al.
Table 3 Thermodynamic parameters of the ligand and its complexes using the Coats–Redfern (CR) equation
Complexes
Radius metal
ion/pm
DTGmax
°C
/
E*/
kJmol-1
A/s-1
DS*/JK-1
DH*/
DG*/
r
mol-1
kJg-1
kJmol-1
C7H8N4O (L)
–
143
281
292
225
238
125
267
190
188
15.1
38.1
35.2
21.2
20.6
27.5
26.5
24.3
23.3
5.64 9 104
2.65 9 107
2.34 9 106
3.21 9 108
2.98 9 109
3.55 9 108
2.98 9 109
5.11 9 105
3.91 9 106
-2.13
-1.68
-1.77
-1.29
-1.32
-1.65
-1.88
-2.45
-2.32
16.5
19.8
20.6
12.4
11.9
12.8
13.5
26.2
20.9
13.2
21.6
21.1
21.3
20.8
21.9
30.7
19.8
19.5
0.9652
0.9812
0.9652
0.9564
0.9953
0.9971
0.9987
0.9876
0.9965
[Mn(L)2]Cl2 MnC14H16N8O2Cl2
[Mn(L)2](NO3)2 MnC14H16N10O8
[Co(L)2]Cl2 CoC14H16N8O2Cl2
[Co(L)2](NO3)2 CoC14H16N10O8
[Ni(L)2]Cl2 NiC14H16N8O2Cl2
[Ni(L)2](NO3)2 NiC14H16N10O8
[Cu(L)2]Cl2 CuC14H16N8O2Cl2
[Cu(L)2](NO3)2 CuC14H16N10O8
46
74.5
69
73
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123