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M.A. Zayed et al. / Spectrochimica Acta Part A 64 (2006) 216–232
Gly− and PhA− molecules as different fragments is accom-
panied by the appearance of several endo- and exothermic
peaks in the DTA curves as illustrated in Figs. 2–5. The DTA
curve of chelate 19 shows an endothermic peak at 1118 ◦C,
which may be attributed to a phase transition.
fer band. The bands observed are assigned to the transitions
4
4
4T1g (F) → T2g (F) (ν1), 4T1g (F) → A2g (F) (ν2) and 4T1g
4
(F) → T2g (P) (ν3), respectively, suggesting that there is an
octahedral geometry around Co(II) ion [32]. The magnetic
susceptibility measurements lie in the 4.2–5.4 B.M. range
which is an indicative of octahedral geometry [33].
The thermograms of Fe(III) chelates; 8, 14, 20, show
three decomposition steps within the temperature range
25–890 ◦C. Whereas Fe(III) chelate; 2, show four decom-
position steps within the temperature range 25–700 ◦C. The
first step of decomposition within the temperature range
25–165 ◦C corresponds to the loss of water molecules of
3.84%), 1.27% (calcd. for H2O; 1.93%), 3.35% (calcd. for
H2O; 2.81%) and 2.25% (calcd. for H2O; 2.78%) for 2, 8, 14
and 20 chelates, respectively. The DTA curves (Figs. 2b–5b
and Tables 3–6) show that this dehydration step gives
endothermic and/or endo- and exothermic peaks within the
temperature of decomposition. The second, third and fourth
steps (from 120 to 890 ◦C) correspond to the removal of Cl2,
Gly−, PhA−, Pir and Ten molecules leaving metal oxide or
sulphide as a residue. The overall weight loss amounts to
83.71% (calcd. 82.93%), 87.65% (calcd. 87.12%), 83.20%
and 20 chelates, respectively. The decomposition of Pir,
Ten, Gly−, PhA− and Cl2 molecules is accompanied by the
appearance of several exo- and endothermic peaks as shown
in the DTA curves (Figs. 2b–5b and Tables 3–6). Also, phase
The reflectance spectra of Cu(II) ternary chelates in the
presence of Gly (as second ligand) consist of a broad, low
intensity shoulder centered at (17,860–16,340 cm−1) that
forms part of the charge transfer band. The magnetic moment
of 1.95–2.0 B.M. falls within the range normally observed for
octahedral Cu(II) complexes [34]. While, the Cu(II)–ternary
chelates in the presence of PhA (as second ligand) exhibit
a broad band in the region 16,670–15,380 cm−1 assigned
2
to 2Eg → T2g transition and broad band in the region
2
2
14,710–14,160 cm−1 which is assigned to B1g → A1g as
well as a shoulder band in the range 17,540–17,610 cm−1
characteristic of a square planner geometry for Cu(II) com-
plexes [35]. The magnetic moments of the Cu(II)-complexes
are found to be 1.7–1.83 B.M.
In analogy with those described for Zn(II) complexes con-
taining N–O donor Schiff bases [36] and according to the
empirical formulae of these complexes, we proposed an octa-
hedral geometry for the mixed ligand Zn(II) complexes of Pir
and Ten (as primary ligands) and Gly or PhA (as secondary
ligands) with two axial position occupied by the two glycine
molecules or water molecules in case of Pir or Ten mixed
ligand complexes with PhA.
3.3. Thermal analyses (TGA and DTA)
The Co(II) complexes; 3, 9, 15 and 21, exhibit three
to four steps of decomposition as given by TGA analy-
ses (Figs. 2c–5c). The first decomposition step (within the
temperature range 25–195 ◦C) corresponds to the loss of
4H2O (mass loss 7.87%; calcd. 7.65%), 3.5H2O (mass loss
6.65%; calcd. 6.67%), (1/2)Cl2 (mass loss 5.22%; calcd.
5.68%), and (1/2)Cl2 and H2O (mass loss 7.64%; calcd.
8.01%) for 3, 9, 15 and 21 chelates, respectively. The
exo- and endothermic peaks have been observed in the
DTA curves (Figs. 2c–5c) within the temperature range of
this dehydration step. The loss of coordinated water, Pir,
Ten, Gly− and PhA molecules takes place within the tem-
(calcd. 84.38%), 85.07% (calcd. 84.41%), 83.17% (calcd.
82.33%) and 81.60% (calcd. 80.76%) for 3, 9, 15 and 21
chelates, respectively. According to the DTA curves, given in
Figs. 2c–5c, these decomposition steps give several exo- and
endothermic peaks as the result of elimination of the ligand
molecules to different fragments.
The TGA curves of the Ni(II)-ternary chelates, namely 4,
10, 16 and 22, show three to four stages of decomposition
within the temperature range of 25–750 ◦C. The first stage
at 25–210 ◦C corresponds to the loss of water molecules of
hydration and (1/2)Cl2 gas, while the second, third and fourth
stages involve the loss of Pir, Ten, Gly−, PhA− and coordi-
nated water molecules. The overall weight loss amounts to
92.03% (calcd. 92.03%), 91.34% (calcd. 92.06%), 88.63%
The TGA, DTG and DTA curves of the ternary chelates
are shown in Figs. 2–5 and the results are listed in Tables 3–6.
points to the light.
The thermograms of Fe(II)-ternary chelates, namely 1,
7, 13 and 19, show three decomposition steps within the
temperature range 25–830 ◦C (Figs. 2a–5a). The first step
of decomposition, within the temperature range 25–200 ◦C,
corresponds to the loss of hydrated water molecules with a
for 5H2O; 9.29%), 8.0% (calcd. for 0.5SO42−; 7.56%) and
8.15% (calcd. for 0.5SO42− and 0.5H2O; 8.53%) for 1, 7, 13
and 19 chelates, respectively. The DTA curves, illustrated in
Figs. 2a–5a, show that this dehydration step is endothermic
process for chelates 1 and 7, while for chelates 13 and 19,
an exo- and endothermic peaks are appeared as the result
of dehydration and sulphate elimination. The second and
third steps in the temperature range 185–830 ◦C; correspond
to the elimination of coordinated water, Pir, Ten, Gly− and
PhA− molecules leaving metal disulphide (in case of 1 and
7 chelates) or metal oxide (in case of 13 and 19 chelates) as
a residue. The overall weight loss amounts to 87.86% (calcd.
87.33%), 88.17% (calcd. 87.61%), 89.33% (calcd. 88.66%)
and 89.40% (calcd. 89.23%) for 1, 7, 13 and 19 chelates,
respectively. The elimination of coordinated water, Pir, Ten,