A comparative study on the thermal decomposition of some transition metal carboxylates

Article abstract of DOI:10.1007/s10973-005-7120-y

Thermal decomposition of transition metal malonates, MCH₂C ₂O₄ xH₂O and transition metal succinates, M(CH₂)₂C₂O₄ xH₂O (M=Mn, Fe, Co, Ni, Cu, Zn) has been studied employing TG, DTG, DTA, XRD, SEM, IR and Moessbauer spectroscopic techniques. After dehydration, the anhydrous metal malonates and succinates decompose directly to their respective metal oxides in the temperature ranges 310-400 and 400-525°C, respectively. The oxides obtained have been found to be nanosized. The thermal stability of succinates have been found to be higher than that of the respective malonates.

Full text of DOI:10.1007/s10973-005-7120-y

Journal of Thermal Analysis and Calorimetry, Vol. 85 (2006) 2, 417–424
A COMPARATIVE STUDY ON THE THERMAL DECOMPOSITION OF
SOME TRANSITION METAL CARBOXYLATES
B. S. Randhawa* and K. Gandotra
Department of Chemistry, Guru Nanak Dev University, Amritsar, India
Thermal decomposition of transition metal malonates, MCH2C2O4⋅xH2O and transition metal succinates, M(CH2)2C2O4⋅xH2O
(M=Mn, Fe, Co, Ni, Cu, Zn) has been studied employing TG, DTG, DTA, XRD, SEM, IR and Mössbauer spectroscopic techniques.
After dehydration, the anhydrous metal malonates and succinates decompose directly to their respective metal oxides in the temper-
ature ranges 310–400 and 400–525°C, respectively. The oxides obtained have been found to be nanosized. The thermal stability of
succinates have been found to be higher than that of the respective malonates.
Keywords: metal malonates, metal succinates, SEM, thermal decomposition, thermogravimetry, XRD
Introduction
Experimental
The last three decades have witnessed a phenomenal
progress in the field of thermal analysis especially in
instrumentation and widening scope of its applications.
The application of thermal techniques encompasses a
wide spectrum of fields ranging from pure and applied
sciences to technology. In fact, the data derived using
thermoanalytical techniques have contributed signifi-
cantly to the evolution of a large variety of high-tech
materials used in the specialized areas of science and
technology. As a result, thermal analysis has become a
very popular tool in both academic and industrial orga-
nizations for characterization, performance evaluation
and determination of process parameters of various
types of materials. Thermal decomposition of metal
carboxylates has become a subject of recent interest in
view of their diverse applications. The appreciable
complexing ability and ease of decomposition and
availability at a reasonable cost, make them potentially
useful as water proofing materials, flattening and soft-
ening agents, hydrogenation catalysts, greases, lubri-
cants, cosmetics, pesticides, etc. [1, 2]. The final
thermolysis products (metal oxides) are extensively
used as catalysts, ceramic colorants, photoconductors
and gas sensors [3–5]. Although a detailed study on
thermal analysis has been reported for transition metal
oxalates [6], a similar interest on respective malo-
nates/succinates is lacking. The present investigation
on thermolysis of transition metal (M=Mn, Fe, Co, Ni,
Cu, Zn) malonate/succinates has been, therefore, un-
dertaken with a view to study the effect of increasing
carbon chain length (malonates→succinates) on their
thermal stabilities.
Transition metal malonates, MCH2C2O4⋅xH2O (M= Mn,
Fe, Co, Ni, Cu, Zn) were prepared by mixing stoichio-
metric quantities of aqueous solutions of respective
transition metal carbonates and malonic acid. The resul-
tant solution was heated overnight at 60°C. The reaction
mixture was cooled and filtered by using suction pump.
After washing with ethanol and air-drying, the com-
pound was stored in a desiccator. On the other hand,
transition metal succinates, M(CH2)2C2O4⋅xH2O (M=
Mn, Fe, Co, Ni, Cu, Zn) were prepared by mixing with
constant stirring the stoichiometric quantities of aque-
ous solutions of succinic acid and respective transition
metal sulphate. The precipitates formed after sometime
were isolated, washed with ethanol, allowed to air-dry
and stored in a vacuum desiccator. The percentage of
manganese in manganese malonate/succinate was deter-
mined titrimetrically using Eriochrome Black-T as indi-
cator [7]. The content of iron in iron malonate/succinate
was determined spectrophotometrically using 1,10-
phenanthroline method [7]. The contents of cobalt,
nickel, copper and zinc in respective malonates/
succinates were determined electrogravimetrically [7].
The identity of these compounds was established by ele-
mental analysis (Table 1).
For non-isothermal studies, simultaneous thermal
analysis (TG-DTG-DTA) curves were recorded on a
Stanton Redcraft (STA-780) model at a heating rate of
10°C min–1. These studies were performed in static air
atmosphere at USIC, IIT, Roorkee. The infrared spec-
tra of transition metal succinates in the range
4000–200 cm–1 were recorded on PYE-UNICAM
SP3-300 IR spectrophotometer using KBr matrix. The
*
Author for correspondence: balwinderrandhawa@yahoo.co.in
1388–6150/$20.00
Akadémiai Kiadó, Budapest, Hungary
Springer, Dordrecht, The Netherlands
© 2006 Akadémiai Kiadó, Budapest

RANDHAWA, GANDOTRA
Table 1 Microanalytical data for various transition metal
malonates and succinates
(carboxylate) bonding [8]. The IR spectra of other
transition metal carboxylates are almost similar to
that of manganese malonate dihydrate.
Compound
C/%
H/%
M/%
The compoundwise discussion on thermolysis of
various transition metal carboxylates follows.
obs. 17.42
calc. 18.65
3.07
3.11
28.10
28.50
MnCH2C2O4⋅2H2O
obs. 24.10
calc. 24.24
3.21
3.53
27.56
27.78
Mn(CH2)2C2O4⋅1.5H2O
FeCH2C2O4⋅H2O
Manganese malonate dihydrate, MnCH2C2O4 2H2O
obs. 19.80
calc. 20.45
2.01
2.27
30.70
31.81
Figure 1 shows the simultaneous thermal analysis
curves (TG-DTG-DTA) of manganese malonate
dihydrate at a heating rate of 10°C min–1. The com-
pound undergoes decomposition in two steps. The first
step is the dehydration, which commences at 163°C
and completes at 230°C as indicated by a mass loss of
19% due to the removal of two water molecules. DTA
and DTG show corresponding peaks at 205°C (endo-
thermic) and 200°C, respectively, suggesting that ther-
mal changes are accompanied by mass loss. The high
temperature of dehydration indicates that both the wa-
ter molecules are coordinated ones. The anhydrous
compound remains stable upto 290°C as shown by an
arrest in TG and then undergoes a rapid oxidative de-
composition process as shown by a strong exotherm at
315°C followed by a sharp DTG peak. This rapid de-
composition step leads to a mass loss of 62.5% at
330°C indicating the formation of manganese oxide,
MnO (calc. loss=63%). The presence of manganese
oxide as a final thermolysis product has been con-
firmed by XRD powder data which agree to that re-
ported for MnO [9]. IR spectrum of the residue ob-
tained by heating the parent complex isothermally at
400°C for 3 h shows characteristic bands in the range
300–540 cm–1 due to Mn–O bonding [10]. Manganese
obs. 21.84
calc. 22.21
3.92
4.15
24.03
25.81
Fe(CH2)2C2O4⋅2.5H2O
CoCH2C2O4⋅H2O
obs. 19.90
calc. 20.12
2.15
2.23
32.66
32.92
obs. 19.24
calc. 19.44
4.51
4.86
23.42
23.86
Co(CH2)2C2O4⋅4H2O
NiCH2C2O4⋅2H2O
Ni(CH2)2C2O4⋅4H2O
CuCH2C2O4⋅2H2O
Cu(CH2)2C2O4⋅2H2O
ZnCH2C2O4⋅2H2O
Zn(CH2)2C2O4
obs. 18.20
calc. 18.30
2.93
3.05
29.06
29.84
obs. 19.20
calc. 19.45
4.73
4.86
22.86
23.79
obs. 17.69
calc. 17.86
2.84
2.98
30.00
31.50
obs. 22.06
calc. 22.27
3.63
3.71
29.15
29.46
obs. 16.39
calc. 17.73
2.81
2.95
31.80
32.02
obs. 28.26
calc. 28.74
2.15
2.39
37.80
38.92
room temperature X-ray diffraction (XRD) powder
data were recorded at Soils Department, P.A.U.,
Ludhiana using nickel filtered CuKα radiation. The
scanning electron microscopic (SEM) studies for de-
termining the particle size were carried out using JEOL
scanning electron microscope at RSIC, Panjab Univer-
sity, Chandigarh. For iron carboxylates, Mössbauer
studies were performed at Laboratoire de Physique,
Université du Maine, France using conventional trans-
mission spectrometer with constant acceleration drive
and isomer shift values have been reported with respect
to pure iron absorber.
Results and discussion
IR spectrum of manganese malonate dihydrate shows
a broad band centered at about 3400 cm–1 due to νOH
of lattice water. A shoulder at 2950 cm–1 is assigned
to νC–H of malonate ligand. A strong band at
1585 cm–1 is due to νasym(C=O) whereas a sharp band at
1405 cm–1 alongwith a shoulder at 1460 cm–1 is attrib-
uted to νsym(C=O) of malonate group. Bands in the
range 1210–985 cm–1 correspond to (O–H) bending
mode. A sharp band at 815 cm–1 is associated with
cis(C–H) wagging and distinct bands in the range
290–585 cm–1 indicate the presence of Mn–O
Fig. 1 Simultaneous TG-DTG-DTA curves of manganese
malonate dihydrate
418
J. Therm. Anal. Cal., 85, 2006

SOME TRANSITION METAL CARBOXYLATES
oxalate is also reported to decompose directly to man-
step is associated with a mass loss of 64% at 420°C
indicating the formation of manganese oxide, MnO
(calc. loss=64%). The presence of manganese oxide
as the final thermolysis product has been confirmed
by XRD powder data which agree to that reported for
MnO [9]. IR spectrum of the final residue resembles
to that observed for respective malonate salt. MnO is
reported to be stable upto 600°C [11].
ganese oxide without yielding carbonate as an interme-
diate [6]. SEM micrograph (Fig. 2) reveals the forma-
tion of MnO with an average particle size of 75 nm.
Manganese succinate sesquehydrate,
Mn(CH2)2C2O4·1.5H2O
Figure 3 shows the simultaneous thermal analysis
curves (TG-DTG-DTA) of manganese succinate
sesquehydrate at a heating rate of 10°C min–1. The
compound undergoes decomposition in two steps.
The first step is dehydration, which commences at
152 and completes at 215°C as indicated by a mass
loss of 13% (calc. loss=13.6%). DTA and DTG show
corresponding broad peaks centered at 205 (endother-
mic) and 208°C, respectively. The anhydrous com-
pound remains stable upto 310°C and then undergoes
an abrupt oxidative decomposition process as shown
by a strong exotherm at 380°C via the formation of an
unstable intermediate species (supported by a shoul-
der in DTA and DTG at 347°C). This decomposition
Ferrous malonate monohydrate, FeCH2C2O4 H2O
Figure 4 shows the simultaneous thermal analysis
curves (TG-DTG-DTA) of iron(II) malonate mono-
hydrate. The dehydration commences at 66 and com-
pletes at 204°C as shown by a mass loss of 10.0% due to
the removal of one-water molecule (calc. loss= 10.2%).
The anhydrous compound remains stable upto 269°C
and starts decomposing gradually. After passing
through multistep oxidative decomposition process (as
supported by DTG peaks and an exothermic region from
269 to 484°C), it ultimately decomposed to oxide as
shown by a mass loss 56% (calc. loss 56%). The identity
of iron oxide has been confirmed by XRD powder pat-
tern, which resembles to that reported for α-Fe2O3 [12].
IR spectrum of the residue obtained by calcining the
parent complex isothermally at 500°C for 2 h shows
small intense bands in the region 550–350 cm–1 due to
ν(Fe–O). Mössbauer spectrum of the end product exhib-
its a six-line pattern (Fig. 5) with isomer shift and inter-
nal magnetic field values of 0.40 mm s–1 and 505 kOe,
respectively. These parameters are in close agreement to
those reported for α-Fe2O3 [13]. SEM micrograph
(Fig. 6) reveals the formation of α-Fe2O3 with an aver-
age particle size of 88 nm. However, after sintering at
800°C for 3 h, the particle size increased to 600 nm
(Fig. 7). An increase in particle size/diameter of
α-Fe2O3 with increasing sintering temperature has also
been reported in literature [14].
Fig. 2 SEM micrograph of the final thermolysis residue of
manganese malonate dihydrate (MnO), sintered at
400°C for 3 h
Fig. 4 Simultaneous TG-DTG-DTA curves of ferrous
Fig. 3 Simultaneous TG-DTG-DTA curves of manganese
malonate monohydrate
succinate sesquehydrate
J. Therm. Anal. Cal., 85, 2006
419

RANDHAWA, GANDOTRA
Fig. 5 Mössbauer spectrum of Fe(II) malonate monohydrate
calcined at 500°C
Fig. 8 Simultaneous TG-DTG-DTA curves of ferrous
succinate sesterhydrate
150°C (calc. loss=21%). The corresponding DTG peak
occurs at 120°C which is endothermic in DTA. The an-
hydrous compound remains stable upto 265°C and
then undergoes an abrupt oxidative decomposition
process till a mass loss of 62% is reached at 400°C sug-
gesting the formation of Fe2O3 (calc. loss=62.5%). Al-
though DTG shows that this oxidative process occurs
in two steps, however TG and DTA exhibit only one
step. The presence of iron oxide as α-Fe2O3 has been
confirmed by XRD powder pattern and Mössbauer
spectrum of the final residue.
Fig. 6 SEM micrograph of the final thermolysis residue of
Fe(II) malonate monohydrate (α-Fe2O3), sintered at
500°C for 3 h
Cobalt malonate dihydrate, CoCH2C2O4·2H2O
Figure 9 shows the simultaneous thermal analysis
curves (TG-DTG-DTA) of cobalt malonate dihydrate
at a heating rate of 10°C min–1. The compound under-
goes decomposition in two steps. The first step is the
dehydration which starts at 169 and completes at
234°C as indicated by a mass loss of 18%. DTA and
DTG peaks show corresponding peaks at 204 (endo-
thermic) and 202°C, respectively. The anhydrous
compound remains stable upto 270°C and then under-
goes a rapid decomposition process as shown by a
strong exotherm with maximum peak temperature of
325°C, followed by a large DTG peak. Although
DTG and DTA (exothermic) curves show a multistep
decomposition process, the slope of TG indicates
only one major oxidative step leading to the forma-
tion of a stable product. The shoulders in DTG and
DTA peaks may be due to some short-lived unstable
intermediate species which subsequently oxidized to
cobalt oxide. Formation of cobalt oxide as the final
thermolysis product has been confirmed by XRD
Fig. 7 SEM micrograph of the final thermolysis residue of Fe(II)
malonate dihydrate (α-Fe2O3), sintered at 800°C for 3 h
Ferrous succinate sesterhydrate,
Fe(CH2)2C2O4·2.5H2O
Figure 8 shows the simultaneous thermal analysis
curves (TG-DTG-DTA) of ferrous succinate sester-
hydrate at a heating rate of 10°C min–1. The dehydra-
tion occurred in two steps. In the first step, there is a
loss of 4% indicating the removal of half water mole-
cule (calc. loss=4.15%). There are respective small
DTA (endothermic) and DTG peaks at 65°C. A further
mass loss of 18% in the second stage suggests the re-
moval of another installment of two water molecules at
420
J. Therm. Anal. Cal., 85, 2006

SOME TRANSITION METAL CARBOXYLATES
Fig. 9 Simultaneous TG-DTG-DTA curves of cobalt malonate
Fig. 11 Simultaneous TG-DTG-DTA curves of cobalt
dihydrate
succinate tetrahydrate
ide (CoO). Existence of CoO as the final thermolysis
products has been confirmed by XRD powder pattern
and IR spectrum of the ultimate residue.
Nickel malonate dihydrate, NiCH2C2O4·2H2O
The decomposition pattern of nickel malonate di-
hydrate is almost similar to that observed for its cobalt
counterpart.
Fig. 10 SEM micrograph of the final thermolysis residue of co-
Nickel succinate tetrahydrate, Ni(CH2)2C2O4·4H2O
balt malonate dihydrate (CoO), sintered at 400°C for 3 h
Figure 12 shows the simultaneous thermal analysis
curves (TG-DTG-DTA) of nickel succinate tetra-
hydrate at a heating rate of 10°C min–1. The com-
pound undergoes decomposition in two steps. The
first step is the dehydration which commences at 114
and completes at 200°C as shown by a mass loss of
29% (calc. loss=29.2%). Corresponding DTA (endo-
thermic) and DTG peaks lie at 153 and 150°C, respec-
tively. The anhydrous compound remains stable upto
380°C and then undergoes an abrupt oxidative de-
composition process till a mass loss of 70% is ob-
tained at 450°C indicating the formation of NiO
(calc. loss=70.0%). Although DTA shows that this
oxidation process occurs in two steps, however TG
and DTG (peak temperature 410°C) exihibt only sin-
gle step. Formation of nickel oxide as the final
thermolysis product has been confirmed by XRD
powder pattern which agrees to that reported for
NiO [16]. IR spectrum shows a characteristic band at
480 cm–1 due to νNi–O bonding.
powder pattern which agrees to that reported for
CoO [15]. IR spectrum of the final residue shows
characteristic νCo–O bands in the range 480–300 cm–1.
SEM micrograph (Fig. 10) reveals the formation of
CoO with an average particle size of 85 nm.
Cobalt succinate tetrahydrate, Co(CH2)2C2O4·4H2O
Figure 11 shows the simultaneous thermal analysis
curves (TG-DTG-DTA) of cobalt succinate tetra-
hydrate at a heating rate of 10°C min–1. An initial mass
loss of only one percent at 51°C may correspond to
desorption of the absorbed gases. The compound then
undergoes dehydration, which completes at 180°C as
shown by a mass loss of 29% (calc. loss=29.2%). The
corresponding DTG and DTA (endothermic) peaks
both lie at 160°C. The anhydrous compound remains
stable upto 330°C and then undergoes an abrupt de-
composition process upto 420°C as shown by DTA
peak (exothermic) at 372°C. This decomposition pro-
cess is associated with a mass loss of 69.5%
(calc. loss=70%) indicating the formation of cobalt ox-
J. Therm. Anal. Cal., 85, 2006
421

RANDHAWA, GANDOTRA
unstable short-lived intermediate might have oxidized
immediately after its formation. DTG also shows a
shoulder corresponding to this step. These thermal
changes are accompanied by a mass loss of 64.5% at
300°C suggesting the formation of copper(I) oxide,
Cu2O (calc. loss=64.52%). However, Cu2O formed
underwent oxidation above 315°C (as supported by
an exotherm) resulting in an increase of mass by ap-
proximately 4% due to its transition to copper(II) ox-
ide (CuI→CuII). The identity of the final thermolysis
product has been confirmed by XRD powder pattern
which agrees to that reported for CuO [17]. IR spec-
trum of the final residue also shows a distinct band at
475 cm–1 due to νCu–O bonding.
Copper succinate dihydrate, Cu(CH2)2C2O4·2H2O
Figure 14 shows the simultaneous thermal analysis
curves (TG-DTG-DTA) of copper succinate di-
hydrate at a heating rate of 10°C min–1. The dehydra-
tion starts at 66 and completes at 120°C as shown by a
mass loss of 17% in TG (calc. loss=16.7%). There are
corresponding broad DTA (endothermic) and DTG
peaks centered at 100 and 105°C, respectively. The
anhydrous compound remains stable upto 315°C and
then undergoes a rapid oxidative pyrolysis till a mass
loss of 63% is obtained at 440°C indicating the for-
mation of CuO. The presence of a doublet in DTA and
a shoulder in DTG suggests that initially copper(I)
oxide (Cu2O) is formed (as supported by a mass loss
of 67% at 355°C), which at higher temperature oxi-
dizes to copper(II) oxide, CuO thereby decreasing the
final mass loss to 63% due to oxidation of Cu(I) to
Cu(II) state. The existence of CuO as the end product
Fig. 12 Simultaneous TG-DTG-DTA curves of nickel
succinate tetrahydrate
Copper malonate dihydrate, CuCH2C2O4·2H2O
Figure 13 shows the simultaneous thermal analysis
curves (TG-DTG-DTA) of copper malonate dihydrate
at a heating rate of 10°C min–1. The compound under-
goes decomposition in two steps. The first step is de-
hydration which commences at 107 and is completed
at 190°C as indicated by a mass loss of 16%. DTA
and DTG show corresponding peaks at 133 (endo-
thermic) and 130°C, respectively. The anhydrous
compound remains stable upto 225°C and then under-
goes a small endothermic decomposition step which
subsequently becomes exothermic indicating that an
Fig. 14 Simultaneous TG-DTG-DTA curves of copper
Fig. 13 Simultaneous TG-DTG-DTA curves of copper
succinate dihydrate
malonate dihydrate
422
J. Therm. Anal. Cal., 85, 2006

SOME TRANSITION METAL CARBOXYLATES
has been confirmed by XRD powder pattern and IR
spectrum of the final residue.
Zinc malonate dihydrates, ZnCH2C2O4·2H2O
Figure 15 shows the simultaneous thermal analysis
curves (TG-DTG-DTA) of zinc malonate dihydrate at a
heating rate of 10°C min–1. The compound undergoes
decomposition in two steps. The first step is the dehy-
dration, which commences at 130 and completes at
192°C as indicated by a mass loss of 17% due to the re-
moval of two water molecules (calc. loss=17.7%). DTA
and DTG show corresponding peaks at 165 (endother-
mic) and 170°C, respectively. The anhydrous com-
pound remains stable upto 258°C and then undergoes a
rapid decomposition process as shown by a strong
exotherm at 305°C followed by a large DTG peak at
310°C. Although DTG shows more than one decompo-
sition stages, TG suggests only a single major step. A
mass loss of 60% for this step corresponds to the forma-
tion of zinc oxide (calc. loss=60%). The identity of the
final thermolysis product has been confirmed by XRD
powder pattern which resembles to that reported for
ZnO [18]. IR spectrum of the final residue shows a
sharp band at 490 cm–1 due to νZn–O bonding.
Fig. 16 Simultaneous TG-DTG-DTA curves of zinc succinate
confirmed by XRD powder pattern and IR spectrum
of the final thermolysis residue.
On the basis of various physico-chemical stud-
ies, the following mechanisms for the thermolysis of
transition metal malonates (A) and succinates (B) in
air are proposed:
MCH2C2O4⋅xH2O⎯d⎯ehyd⎯ration⎯, 190⎯–29⎯0°C→
⎯d⎯ehyd⎯ratio⎯n, 190⎯–29⎯0°C→MCH2C2O4
A(i)
(M=Mn, Fe, Co, Ni, Cu, Zn)
MCH2C2O4⎯d⎯ecom⎯posi⎯tion, ⎯325–⎯48⎯5°C→MO(s)+
+1/2C2H4(g)+3/2CO (g)+1/2CO2(g)
(M=Mn, Co, Ni, Cu, Zn)
A(ii)
FeCH2C2O4⎯d⎯ecom⎯posi⎯tion, ⎯48⎯4°C→1/2α-Fe2O3(s)+
+1/2C2H4(g)+3/2CO(g)+1/2CO2(g)
M(CH2)2C2O4⋅xH2O⎯d⎯ehyd⎯ratio⎯n, 120⎯–21⎯5°C→
⎯d⎯ehyd⎯ration⎯, 120⎯–21⎯5°C→M(CH2)2C2O4
B(i)
M(CH2)2C2O4 ⎯d⎯ecom⎯posi⎯tion, ⎯400–⎯52⎯5°C→MO(s)+
+C2H4(g)+CO(g)+CO2(g)
(M=Mn, Co, Ni, Cu, Zn)
B(ii)
Fig. 15 Simultaneous TG-DTG-DTA curves of zinc malonate
dihydrate
Fe(CH2)2C2O4⎯d⎯ecom⎯posi⎯tion, ⎯40⎯0°C→1/2α-Fe2O3(s)+
+C2H4(g)+3/2CO(g)+1/2CO2(g)
Zinc succinate, Zn(CH2)2C2O4
Figure 16 shows the simultaneous thermal analysis
curves (TG-DTG-DTA) of zinc succinate at a heat-
ing rate of 10°C min–1. Being anhydrous, the com-
pound undergoes decomposition in one step only.
After remaining stable upto 428°C, it undergoes an
abrupt oxidative decomposition process upto 522°C
leading to a mass loss of 55% revealing the forma-
tion of ZnO (calc. loss=55.2%). Although DTA and
DTG show this oxidative decomposition to be
multistep process, TG exhibits only one step. The
presence of ZnO as the ultimate product has been
Conclusions
Transition metal (M=Mn, Fe, Co, Ni, Cu, Zn)
malonates and succinates decompose directly to re-
spective oxides. Transition metal ferricarboxylates
[19, 20] have also been reported to decompose di-
rectly to their respective oxides. The oxides obtained
are nanosized as revealed by SEM analysis.
J. Therm. Anal. Cal., 85, 2006
423

RANDHAWA, GANDOTRA
9 ASTM Card Number 7-230.
A
comparative study of transition metal
10 R. A. Nyguist and R. O. Kagel, Infrared Spectra of Inor-
ganic Compounds, Academic Press, 1971.
11 D. A. Edwards and R. N. Hayward, Can. J. Chem.,
46 (1968) 3443.
succinates and respective malonates reveals the fol-
lowing stability order:
succinates>malonates
12 ASTM Card Number 13-534.
The transition metal succinates are thermally more
stable than the respective malonates. This is attributed to
the fact that two methylene groups present in the succi-
nates prevent the direct interaction between carboxylate
groups, thus causing their slow breakdown [21].
13 S. S. Bellad, C. D. Lokhande and C. H. Bhosale,
Indian J. Pure Appl. Phys., 35 (1997) 565.
14 B. S. Randhawa and P. S. Bassi,
Radiochem. Radioanal. Letts., 59 (1983) 171.
15 ASTM Card Number 9-402.
16 JCPDS Card Number 4-0835.
17 ASTM Card Number 5-0661.
18 ASTM Card Number 5-0664.
References
19 O. Carp, L. Patron, G. Marinescu, G. Pascu and
P. Budrugeac, J. Therm. Anal. Cal., 72 (2003) 263.
20 B. S. Randhawa, K. J. Sweety, Manpreet Kaur and
J. M. Greneche, J. Therm. Anal. Cal., 75 (2004) 101.
21 A. K. Galway and M. A. Mohamed, J. Chem. Soc. Faraday,
81 (1985) 2503.
1 E. Markowicz, Farben-Ztg., (1928) 34,336,414,503.
2 K. N. Mehrotra and S. C. Bhargav, Z. Phys. Chem.,
237 (1968) 327; Chem. Abst., 69 (1968) 37364.
3 A.-S. Malik, M. J. Duncan and P. G. Bruce, J. Mater. Chem.,
13 (2003) 2123.
4 V. E. Henrich and P. A. Cox, The Surface Science of
Metal Oxides, Cambridge University Press, 1994.
5 R. C. Mehrotra and R. Bohra, Metal Carboxylates,
Academic Press, New York 1983.
Received: January 20, 2005
Accepted: May 2, 2005
OnlineFirst: December 12, 2005
6 D. Dollimore and D. L. Griffiths, J. Thermal Anal.,
2 (1970) 229.
7 A. I. Vogel, Quantitative Inorganic Analysis, 3rd Ed.,
DOI: 10.1007/s10973-005-7120-y
Longman Group Ltd., England 1973.
8 K. Nakamoto, Infrared Spectra of Inorganic and Coordina-
tion Compounds, 2nd Ed., John Wiley Intersci.,
New York 1970.
424
J. Therm. Anal. Cal., 85, 2006