Copper(II) acetates with aliphatic/heterocyclic amines: Coupled TG-DTA-EGA study, IR characterization and structure correlation

Article abstract of DOI:10.1007/s10973-005-0959-0

Three copper acetate complex compounds, namely Cu(CH₃COO) ₂(en)₂?2H₂O (I), Cu(CH₃COO) ₂(tn)₂(II) and Cu₂(CH₃COO) ₄(pyz) (III) (en=ethylenediamine, tn=1,3-diaminopropane, pyz=pyrazine), were prepared and characterized during heating in argon by thermogravimetry (TG), differential thermal analysis (DTA) and evolved gas analysis (EGA) using mass spectrometry (MS). The results of infrared spectroscopy (IR) were evaluated to be used as a spectroscopic criterion for the determination of the carboxylate binding mode in the compounds.

Full text of DOI:10.1007/s10973-005-0959-0

Journal of Thermal Analysis and Calorimetry, Vol. 82 (2005) 747–754
COPPER(II) ACETATES WITH ALIPHATIC/HETEROCYCLIC AMINES
Coupled TG-DTA-EGA study, IR characterization and structure correlation
V. Zele×ák1*, Z. Vargová1, K. Györyová1, E. Ve¹erníková2 and V. Balek3
1Institute of Chemical Science, Faculty of Sciences, P. J. Šafárik University, Moyzesova 11, 041 54 Košice, Slovak Republic
2 Institute of Inorganic Chemistry, AS CR, 250 68 Reꢀ, Czech Republic
3Nuclear Research Institute, 250 68 Reꢀ, Czech Republic
Three copper acetate complex compounds, namely Cu(CH3COO)2(en)2·2H2O (I), Cu(CH3COO)2(tn)2 (II) and Cu2(CH3COO)4(pyz)
(III) (en=ethylenediamine, tn=1,3-diaminopropane, pyz=pyrazine), were prepared and characterized during heating in argon by
thermogravimetry (TG), differential thermal analysis (DTA) and evolved gas analysis (EGA) using mass spectrometry (MS). The
results of infrared spectroscopy (IR) were evaluated to be used as a spectroscopic criterion for the determination of the carboxylate
binding mode in the compounds.
Keywords: copper acetate, 1,3-diaminopropane, DTA, ethylenediamine, evolved gas analysis, IR spectra, pyrazine, structure cor-
relation, thermogravimetry
Introduction
en=ethylenediamine, tn=1,3-diaminopropane, pyz=
=pyrazine). The complexes were investigated by
means of a coupled TG/DTG-DTA-EGA methods on
heating in argon to characterize their thermal stabil-
ity. Moreover, the correlation of IR spectra of the
complex compounds to the structures was made.
Copper carboxylates attract research interest in the
field of catalysis [1], as antifungal agents [2], enzyme
models [3], or mainly, in the field of molecular mag-
netism [4]. The versatile coordination behaviour of
carboxylate group leads to the formation of systems
of various dimensionalities which exhibit by theory
predictable magnetic properties [4–6]. Such systems
are prepared by reaction of the corresponding
carboxylate salt with bidentate amine (e.g.
ethylenediamine) followed by the addition of a salt
containing non-coordinating anions [7–9] or, by reac-
tion of metal carboxylate with the organic ligand in a
low ligand : metal ratio [10, 11]. The higher ratio of
the reactants leads to the synthesis of bis- or tris-che-
lates. Such chelate compounds, when they are formed
by monocarboxylate ligand, have usually mononuclear
structure, as it was reported for copper acetate com-
plexes of ethylenediamine or diaminopropane [12].
The dicarboxylate complexes (e.g. oxalate) usually
form polymeric compounds [13].
Experimental
Ethylenediamine (en), 1,3-diaminopropane (tn),
pyrazine (pyz) were supplied from Aldrich and used
without further purification. The copper acetate
monohydrate was prepared from copper carbonate
and acetic acid. The prepared product was
recrystallised from water.
Synthesis
Preparation of Cu(CH3COO)2(en)2·2H2O (compound I)
The mass of 0.5 g (2.5 mmol) of the copper acetate
monohydrate was dissolved in 50 mL of the wa-
ter/ethanol mixture (1:1; v/v) and heated to 50°C. Fur-
ther 1,2-diaminoethane (5 mmol) was added dropwise
during stirring. The solution was filtered and the fil-
trate left for a slow evaporation. After several days
the violet crystalline product was recovered. The
crystals of the compound were filtered off, washed
with ethanol and dried over silica gel. Anal. calc. for
Thermal stability of the copper diamine com-
pounds with various counterions (e.g. chloride, sul-
phate, perchlorate, nitrate) was studied [14–21].
However, the detailed information concerning the
thermal properties of the Cu(II) diamine compounds
with carboxylate as counterion are scarce [22, 23]. In
the present work we have prepared mixed copper ace-
tate complexes, namely Cu(CH3COO)2(en)2·2H2O,
Cu(CH3COO)2(tn)2 and Cu2(CH3COO)4(pyz) (where
*
Author for correspondence: zelenak@kosice.upjs.sk
1388–6150/$20.00
Akadémiai Kiadó, Budapest, Hungary
Springer, Dordrecht, The Netherlands
© 2005 Akadémiai Kiadó, Budapest

ZELE+ÁK et al.
C8H26N4O6Cu: C, 28.5; H, 7.7; N, 16.6; Cu, 18.8%.
(I) and 3250, 3160 cm–1 for the compound II. The band
due to the vibrations of the pyrazine ring was observed
at 1485 cm–1 in the compound III. Moreover, the
stretching vibrations of the aromatic C–H groups of the
pyrazine were found at 3096 cm–1.
Found: C, 28.7; H, 7.7; N, 16.2; Cu, 19.1%.
Preparation of Cu(CH3COO)2(tn)2 (compound II)
The acetate anions were characterized by
carboxylate stretches nas(COO–) and ns(COO–) at
1564 and 1396 cm–1 for compound I, 1550 and
1400 cm–1 for compound II and 1596 and 1424 cm–1
for the compound III. The magnitude of the separa-
tion between the stretches (D=nas(COO–)–ns(COO–))
is often used as a spectroscopic criterion for determi-
nation of the mode of the carboxylate binding
[24–30], including biomolecules [31, 32]. The follow-
ing order was proposed for D values of carboxylate
complexes of divalent metal cations [24, 25]:
The copper acetate (0.5 g; 2.5 mmol) was dissolved in
50 mL of the water/ethanol mixture (1:1; v/v) and
5 mmol of tn was added to the solution while the vio-
let solution was formed. The solution was filtered and
left to stand at 50°C. After several days the blue-violet
solid Cu(CH3COO)2(tn)2 was recovered. The prepared
complex compound was highly hygroscopic and there-
fore was kept in desiccator over silica gel. Anal. Calc.
for C10H26N4O4Cu: C, 36.4; H, 7.9; N, 17.0; Cu, 19.3%.
Found: C, 36.2; H, 7.6; N, 16.5; Cu, 18.9%.
D(monodentate)>D(ionic)>D(bridging bidentate)
Preparation of Cu2(CH3COO)4(pyz) (compound III)
>D(chelating bidentate).
This D value is about 170 cm–1 for ionic
carboxylate group in acetates, i.e. group which does
not interact strongly with the metal ion [24]. In
monodentate coordination the redistribution of the
electron density takes place, the force field around the
metal atom changes and consequently the shift in the
frequency of nas(COO–) to higher wavenumbers in
comparison with ionic group is observed, increasing
the value of D. On contrary, bidentate coordination
shifts the position of the asymmetric carboxylate
stretch to lower wavenumbers in comparison with
ionic group and thus lowers the value of D. In the
‘bridging’ coordination when one divalent metal cat-
ion is bound to one of the oxygens in the COO– group
and another divalent metal cation to the other oxygen,
the nas(COO–) band is located at the same position as
that of the ‘ionic’ nas(COO–) band [31].
The compound Cu2(CH3COO)4(pyz) was prepared by
mixing the methanol solution (40 mL) of copper acetate
(0.5 g, 2.5 mmol) with 20 mL of the methanol solution
of pyrazine (0.2 g, 2.5 mmol). The reaction mixture was
stirred at the room temperature for several minutes
while a green powder precipitated. The powder was fil-
tered off, washed with methanol and dried. Anal. Calc.
for C12H16N2O8Cu2: C, 32.5; H, 3.6; N, 6.3; Cu, 28.7%.
Found: C, 32.1; H, 3.5; N, 6.1; Cu, 28.4%.
Instrumentation
TG/DTG-DTA-EGA measurements were carried out
using NETZSCH STA 409 Apparatus equipped with
quadrupole-type mass spectrometer BALZERS. The
measurements were carried out in flow of argon
(75 mL min–1) at the rate 6ºC min–1 and with the sam-
ple mass 50 mg. To identify the solid products of the
thermal decomposition, XRD patterns were recorded
with a Micrometa 2 diffractometer using Cr-Ka, V-fil-
tered radiation (l=2.29092 Å). Elemental analyses
were performed with a PerkinElmer 2400 CHN Ele-
mental Analyser. The copper content was determined
by complexometric titration using EDTA. Infrared
spectra were measured by PerkinElmer 781
spectrophotometer as KBr disc.
This criterion is also frequently used in the papers
dealing with the thermal properties of the complex com-
pounds. However it has to be applied carefully because
sometimes it can be ambiguous or gives misleading re-
sults and can be strongly influenced by the presence of
the hydrogen bonds [33, 34]. During application of this
criterion, the comparison of the proposed mode of the
coordination with the structural data within a series of
closely related compounds is often useful.
First, the above criteria were applied to the com-
pound III, for which the structural data were available
[35]. From the single crystal diffraction study it is
well known, that the compound III forms 1D poly-
meric chains, in which binuclear paddle-wheel ace-
tate units are connected by the pyrazine bridges [35].
For such paddle wheel structure (one copper(II) cat-
ion is bound to one of the two oxygen atoms in the
COO– group and another copper(II) cation to the other
oxygen) the D value should be close to that observed
for ionic carboxylate group [31]. The experimental D
Results and discussion
Spectroscopic characterization of the compounds
The IR spectra revealed the presence of the amines as
well as the acetates in the compounds I–III. The most
important spectral bands are listed in Table 1.
The amine moieties in compounds I and II (en and
tn, respectively) were reflected by the stretching vibra-
tions of the NH2 groups at 3156 cm–1 for the compound
748
J. Therm. Anal. Cal., 82, 2005

COPPER(II) ACETATES WITH ALIPHATIC / HETEROCYCLIC AMINES
Table1 Principal bands in the IR spectra of (I)–(III) and their assignment
Compound
Wavenumber/cm–1
Assignment
Cu(CH3COO)2(en)2·2H2O (I)
3356bs
n(OH)
n(NH)
3156s
2960m, 2900m
n(CH)
1604m
d(H2O)+d(NH2)
nas(COO–)
ns(COO–)
d(CH)
1564s
1396s
1330w, 1270m
1090s, 1048m, 1008m, 922m
r(CH)+r(NH)
d(COO–)
nas(NH)
706s
Cu(CH3COO)2(tn)2 (II)
3250s
3160s
ns(NH)
3096w
n(CH)
2960m
n(CH)
1550s
nas(COO–)
ns(COO–)
d(CH)
1400s
1360m,1310w
1180m,1140m,1060m,960m
r(CH)+r(NH)
d(COO–)
n(CH)
705s
3096s
Cu2(CH3COO)4(pyz) (III)
2900m
n(CH)
1596s
nas(COO–)
1485m
n(pyz)
ns(COO–)
d(CH)
1424s
1340m, 1060m, 1050m
1180m, 1160m
840s
r(CH)
d(COO–)
Abbreviations: b – broad; s – strong; m – medium; w – weak
value, determined from the IR spectra of the com-
pound III (172 cm–1), was in an agreement with this hy-
pothesis. Moreover, based on the knowledge of the
X-ray structural data for the compound III, the D value
can be calculated using Eq. (1), proposed and derived
by Nara [36] from molecular orbital calculations:
structures of the mixed copper ethylenediamine
carboxylate compounds. The survey has shown that
when the both carboxylate and ethylenediamine are
coordinated to copper, the compounds contain usu-
ally one en molecule e.g. in ethylenediamine-phtha-
lato-copper(II) [38], aqua-(ethylenediamine)-(oro-
tato)-copper(II) monohydrate [39] or ethylene-
diamine-bis(2-(methylthio)nicotinato)-copper(II)
[40]. Two en molecules were found in polymeric
bis(oxalato)-bis(1,2-ethylenediamine)-di-copper(II)
where each of two carboxylate groups is coordinated
monodentately [13]. The D values, calculated using
Eq. (1) for these complexes differ remarkably from the
value observed for the compound I. For example the D
value calculated for oxalate (281 cm–1) is in agree-
ment with the monodentate carboxylate coordination
in the compound [13]. The D value calculated for
2-(methylthio)nicotinate (155 cm–1) agrees with chelate
coordination of the carboxylate in this complex [40].
D=1818.1dr+16.47(qOCO –120)+66.8
(1)
where dr is difference between the two CO bond
lengths (Å) and qOCO is the OCO angle (º) [33, 36].
The calculated D value for the complex compound III
is 170.4 cm–1 and it is in agreement with the experi-
mentally observed value (172 cm–1).
For the complexes I and II, there is no entry in
the Cambridge Structural Database [37]. The value of
the separation of the carboxylate stretches, as deter-
mined in our study from the IR spectra of compound I,
is 168 cm–1. This value is close to the value given for
ionic or bridging carboxylate group [24, 31]. To verify
this possibility, we made a survey of the crystal
J. Therm. Anal. Cal., 82, 2005
749

ZELE+ÁK et al.
When two en molecules are present in the com-
lated for ionic nitrobenzoate can be due to hydrogen
bonds, formed by the carboxylate oxygen atoms,
which influenced the bond lengths and angle in the
carboxylate group. Similarly, in the complexes with
monodentately bonded carboxylate, the secondary inter-
action of the non-coordinated carboxylate oxygen atom
with the copper probably lowers the values of D, in com-
parison with those, expected for monodentate coordina-
tion. Such interaction could also be present in the com-
pound III and therefore lower D value was observed
than that typical for monodentate coordination. How-
ever from the IR spectra, the mode of the carboxylate
coordination for the compound III can not be deter-
mined conclusively.
pounds, carboxylate group is frequently ionic. Such
kind of the assembly was found e.g. in aromatic
aminosalicylate [41] and isonicotinate [42] or
aliphatic N-carboxyglycinate [43]. The observed D
value in the latter complex, (167 cm–1), formed by the
aliphatic carboxylate [43] is similar to the value ob-
served for the compound I. The application of Eq. (1)
to the structural data of N-carboxyglycinate gives D
values 177 and 184 cm–1. Therefore the spectral data
suggest that in compound I ‘ionic’ acetate group
could be present. Such assembly could comprise two
ethylediamine molecules coordinated as chelates and
water molecules coordinated to metal ion. The acetate
anions could remain uncoordinated, compensating
the charge of the copper(II) ion.
Thermal stability characterization
For the compound II, the value of the separation D,
as determined from the IR spectra, was 150 cm–1. This
value indicates possibility of chelate acetate group
[26–28]. Anyway, the survey of the crystal structures of
the copper(II) carboxylates with 1,3-diaminopropane
has shown, that in the copper carboxylato complexes of
the formula Cu(tn)2(carboxylato)2, the carboxylate is
usually coordinated to copper atom monodentately
[44–47]. There is one example of the cop-
per-diaminopropane complex with the ¨ionic¨ carbo-
xylate group, but this complex is dihydrate, namely
trans-diaqua-(1,3-diaminopropane)-copper(II) 2-nitro-
benzoate [48]. The D values in nitrobenzoate calcu-
lated using Eq. (1) are 184 and 200 cm–1, and the val-
ues calculated for the tn complexes with the
monodentate carboxylate coordination are in the
range 123–225 cm–1 [44–47]. Higher D values calcu-
Thermal decomposition of Cu(CH3COO)2(en)2·2H2O
(compound I)
The results of TG/DTG, DTA and evolved gas analy-
sis (EGA) obtained for Cu(CH3COO)2(en)2·2H2O
during heating in argon are presented in Fig. 1 and are
summarized in Table 2.
The curves are featureless up to the onset of the
thermal decomposition at 86ºC. Above this tempera-
ture, the dehydration of the sample with loss of one
water molecule took place in the range 86–150°C.
The observed mass loss due to this dehydration was
5.2% (calculated value for one water molecule is
5.3%). The dehydration step was accompanied by an
endothermic effect at 120ºC. The EGA by mass spec-
troscopy (MS) detection reflected the process of the
Table 2 Thermal decomposition data of the complexes I– III
Mass loss/%
Temp.
DTA
MS ions
detected
Step
Product expelled
H2O
Complex
range/°C
peak/°C
Observed
5.2
Calculated
5.3
Cu(CH3COO)2(en)2 ·2H2O (I)
1
2
3
86–150
150–350
350–610
>610
120 endo
18
12, 15, 18, 44
12, 44
179 endo
220 endo
H2O+2en+
70.5
71.2
decomp. of acetate
255 exo
–
Solid
24.3
23.5
23.5
22.5
–
CuO
residue
158 exo
183 exo
Cu(CH3COO)2(tn)2 (II)
1
136–220
15, 18
tn
2
3
220–350
350–750
41
12
40.1
13.3
222 exo
508 exo
12, 15, 44
12, 15, 44
tn+CH3COCH3
CO2
Solid
>750
195–510
>510
23.5
64.7
35.3
24.1
64.1
35.9
–
260 endo
–
–
CuO
residue
total pyrolysis of
the complex
Cu2(CH3COO)4(pyz) (III)
1
12, 15, 18, 44
Solid
–
2CuO
residue
750
J. Therm. Anal. Cal., 82, 2005

COPPER(II) ACETATES WITH ALIPHATIC / HETEROCYCLIC AMINES
acetate was approximately 250°C. The release of the
ethylenediamine was reflected in DTA curve by endo-
thermic effect at 220°C. From 270°C the rate of the ther-
mal decomposition was slowed down. The main decom-
position product detected in this stage was carbon diox-
ide (m/z=44, 12), formed during the decomposition of
the acetate. The DTA curve reflects the decomposition
of acetate by exothermic effects at 255 and 452ºC, re-
spectively.
The mass loss continued up to 560°C (76.9%).
On further heating, in the range 585–610ºC the small
mass increase was observed in the TG curve. We sup-
pose that partial reduction of Cu2+ took place during
heating to 580ºC and above this temperature the
re-oxidation to CuO (the mass increase 1.2%) took
place. As the thermal decomposition was carried out in
the inert atmosphere (Ar, 99.999%), this re-oxidation
was probably by carboxylate oxygen atom. The oxida-
tion process was reflected as a shoulder in the exother-
mic peak at 578°C. The final product of the thermal de-
composition, detected by XRD, was CuO (tenorite;
PDF 45-0937; exp. solid residue 24.3%; calcd. 23.5%).
Fig. 1 TG/DTG-DTA-EGA curves of the complex
Cu(CH3COO)2(en)2·2H2O during heating in argon
Thermal decomposition of Cu(CH3COO)2(tn)2
(compound II)
The TG/DTG, DTA and evolved gas analysis (EGA)
results of the complex compound Cu(CH3COO)2(tn)2
are presented in Fig. 2 and are summarized in Table 2.
The mass loss of 1% observed on the sample heating
up to 91°C due to the release of water adsorbed as hu-
midity by the sample.
dehydration by an increase of the intensity of the mo-
lecular ion of water (m/z=18). The maximal intensity
of the release of this ion was observed at 129ºC. The
second water molecule releases above 150°C. The re-
lease is accompanied by a new maximum at 189°C in
the MS curve measured for the ion with m/z=18 and
by endothermic effect at 179°C in the DTA curve.
During further heating deamination and
decarboxylation of the sample took place. Both steps
coincide in the TG curve, however, the results of MS
suggested, that the process of the deamination took
place as the first. The increase of the intensity of the
fragment ion with m/z=15 from 180°C and ion with
m/z=18 from 195°C was observed in the mass spectrum
(Fig. 1), probably due the evolution of the
ethylenediamine (ions NH4+, NH+). It is to mention that
the intensity of these fragment ions decreased from
about 230°C. However, the decrease of the intensity of
the ion with m/z=15 was remarkably slowed down at
245°C. This was probably due to the onset of the
decarboxylation (i.e. the decomposition of the acetate)
and lose of the fragment ion CH+3 from the acetone or
acetanhydride, which are usually the products of the de-
composition of acetates [49]. This is also supported by
another maximum observed in the EGA curve for the
fragment m/z=44 at the temperature of 262°C. On the
basis of the EGA curves for the fragments (m/z=12, 15,
44), we supposed that the onset of the decomposition of
The compound was thermally stable up to 136°C.
Above this temperature, the evolution of
diaminopropane took place as observed by EGA. In
contrast to compound I the deamination in compound II
took place in two steps. During the first step, in the
range 136–220°C, the mass loss 23.5% was observed,
corresponding to the loss of one molecule of
diaminopropane (calc. mass loss 22.5%). This first step
of the deamination was reflected by the increase of the
intensity of the fragment ions with m/z=15 and 18. The
maximal intensity of these ions was observed at about
200°C. In the range 200–220°C, the intensity of the ions
decreases. This first step of the deamination was accom-
panied in the DTA curve by the exothermic effects with
maximum at 158°C and shoulder at 183°C. Further
heating leads to the evolution of the second molecule of
diamine as well as simultaneous decomposition of the
acetate. This fact was reflected by the increase of the in-
tensity of the ion with m/z=15. The intensity of the re-
lease of the ion with m/z=15 observed at 239°C is higher
than the intensity at 200°C, as both NH+ as well as CH3+
contribute to the intensity of this ion (Fig. 2). Moreover,
the increase of the intensity of the ions with m/z=44 or
J. Therm. Anal. Cal., 82, 2005
751

ZELE+ÁK et al.
From the results of the X-ray structural analysis [35]
it follows, that the structure of the compound III is
polymeric, with Cu2(CH3COO)4 units connected by
pyrazine ligands to 1D chains. The results of the TG
showed, that after attaining of the limit of the stability
at 195°C the collapse of the polymeric structure took
place and the compound decomposed very rapidly by
the steep mass loss (see TG curve in Fig. 3). The pro-
cess of the decomposition took place in the tempera-
ture range 195–360°C and was characterized by the
endothermic effect at 260°C in the DTA curve. The
total mass loss observed on heating up to 360°C was
67.0%. In the range 390–510°C the small mass in-
crease was observed (2%), probably due to re-oxida-
tion of partially reduced Cu2+ to CuO. The amount of
the solid residue after the thermal decomposition
(35.3% of the initial sample mass ) was in a good ac-
cordance with the value calculated for two moles of
CuO (35.9%). The presence of CuO was confirmed
by XRD (tenorite; PDF 45-0937).
From the EGA (MS ) curves it followed that the
maximal intensity of the release of the respective ions
was about 275°C. However, the decrease of the inten-
sity of the anions with m/z=12 and 44 is slower in
comparison to the other, indicating that the kinetics of
the decomposition was determined by the decomposi-
tion of the acetate.
Fig. 2 TG/DTG-DTA-EGA curves of the complex
Cu(CH3COO)2(tn)2 during heating in argon
12 was observed above 220°C, due to the decomposi-
tion of the acetate. The second step of the decomposi-
tion was reflected by the exothermic effect with maxi-
mum at 222°C.
The intensity of the MS curves decreases up to
350°C. The total mass loss, observed at this tempera-
ture was 64.5%, which may correspond to the loss of
the two molecules of diamine and acetone (product of
the decomposition of acetate). The calculated mass
loss, corresponding to the release of these products is
62.6%. Further heating up to 750°C is characterized
by mass decrease of 12%, corresponding release of
the carbon dioxide (calculated value 13.3%) and char-
acterized by the ions m/z=44 and m/z=12 in the MS.
This process of the decomposition was accompanied
by the exothermic peak with the maximum at 508°C
(see DTA results in Fig 2). The solid product of the
thermal decomposition, CuO (observed amount.
23.5%; calculated amount. 24.1%), was confirmed by
XRD to be tenorite (PDF 45-0937).
Thermal decomposition of Cu2(CH3COO)4(pyz)
(compound III)
TG/DTG, DTA and EGA curves of the thermal de-
composition of the compound Cu2(CH3COO)4(pyz)
are presented in Fig. 3 and summarized in Table 2. In
contrast to the two previous compounds the decompo-
sition of the compound III is an one-step process.
Fig. 3 TG/DTG-DTA-EGA curves of the complex
Cu2(CH3COO)4(pyz) during heating in argon
752
J. Therm. Anal. Cal., 82, 2005

COPPER(II) ACETATES WITH ALIPHATIC / HETEROCYCLIC AMINES
14 S. Mathew, C. G. R. Nair and K. N. Ninan, Thermochim.
Conclusion
Acta, 181 (1991) 253.
15 W. W. Wendlandt, J. Inorg. Nucl. Chem., 25 (1963) 833.
16 C. G. R. Nair, S. Mathew and K. N. Ninan, J. Thermal
Anal., 37 (1991) 2325.
It was found by simultaneous TG-DTA–EGA tech-
niques that the thermal decomposition of compounds I
and II is a multistep process, involving dehydration,
deamination and decarboxylation. During the heating of
compound III the collapse of the polymeric structure
takes place rapidly in one step. The processes of
deamination and decarboxylation overlap. However, ac-
cording to the MS data the deamination takes place first,
while the decarboxylation is a slower process.
17 H. Langfelderová, V. Jorík and J. ‡ervená, J. Thermal
Anal., 39 (1993) 489.
18 G. Singh, S. P. Felix and D. K. Pandey, Thermochim.
Acta, 411 (2004) 61.
19 G. Singh and D. K. Pandey, Propell. Explos. Pyrot.,
28 (2003) 231.
20 A. M. Donia, Thermochim. Acta, 320 (1998) 187.
21 G. Wrzeszcz and L. Dobrzanska, Pol. J. Chem.,
77 (2003) 1245.
The values of the separation of the carboxylate
stretches (D) in the IR spectra of the compounds are
frequently used to correlate the IR-spectral data to the
molecular structures of the complexes. Indeed this
criterion is applied in the papers dealing with the ther-
mal properties of the carboxylates. During the demon-
stration of the practical application of this spectro-
scopic criterion it was shown in the present paper that
the criterion does not have general validity as it can
be influenced by various factors (e.g. hydrogen
bonds, non-bonding interactions...). For compounds
I–III, ionic, monodentate and bridging carboxylate
groups were proposed. In accordance with this as-
sumption, compound III showed the highest thermal
stability. For complexes I and II the thermal stability
was lower and determined by the dehydration and
evolution of the amines.
22 L. S. Prabhumirashi and J. K. Khoje, Thermochim. Acta,
383 (2002) 109.
23 P. C. Srivastava, B. N. Singh, S. D. Adhyam and
K. C. Banerji, J. Thermal Anal., 27 (1983) 263.
24 G. B. Deacon and R. J. Phillip, Coord. Chem. Rev.,
33 (1980) 227.
25 D. Martini, M. Pellei, C. Pettinari, B. W. Skelton and
A. H. White, Inorg. Chim. Acta, 333 (2002) 72.
26 D. Czakis-Sulikowska, A. Czylkowska and
A. Malinowska, J. Therm. Anal. Cal., 65 (2001) 505.
27 D. Czakis-Sulikowska and A. Czylkowska, J. Therm.
Anal. Cal., 71 (2003) 395.
28 S. C. Mojumdar, L. Martiška, D. Valigura and M. Melník,
J. Therm. Anal. Cal., 74 (2003) 905.
29 D. Czakis-Sulikowska and A. Czylkowska: J. Therm.
Anal. Cal., 76 (2004) 543.
30 V. Zele×ák, K. Györyová and D. Mlynar¹ík, Metal Based
Drugs, 8 (2002) 269.
31 M. Nara, M. Tasumi, M. Tanokura, T. Hiraoki,
M. Yazawa and A. Tsutsumi, FEBS Letters, 349 (1994) 84.
32 F. Yumoto, M. Nara, H. Kagi, W. Iwasaki, T. Ojima,
K. Nishita, K. Nagata and M. Tanokura, Eur. J. Biochem.,
268 (2001) 6284.
References
1 F. P. W. Agterberg, H. A. J. Provo Kluit, W. L. Driessen,
J. Reedijk, H. Oevering, W. Buijs, N. Veldman, M. T. Lakin
and A. L. Spek, Inorg. Chim. Acta, 267 (1998) 183.
2 B. Kozlevcar, I. Leban, I. Turel, P. Segedin, M. Petric,
F. Pohleven, A.J.P. White, D.J. Williams and J. Sieler,
Polyhedron, 18 (1999) 755.
33 T. Ishioka, Y. Shibata, M. Takahaski, I. Kanesaka,
Y. Kitagawa and K. T. Nakamura, Spectrochim. Acta,
A54 (1998) 1827.
34 Z. Vargová, V. Zele×ák, I. Císaéová and K. Györyová,
Thermochim. Acta, 423 (2004) 149.
3 A. L. Feig and S. J. Lippard, Chem. Rev., 94 (1994) 759.
4 O. Kahn, Molecular Magnetism, VCH Publishers,
Weinheim, Germany, 1993.
35 B. Morosin, R. C. Hughes and Z. G. Soos, Acta
Crystallogr., B31 (1975) 762.
36 M. Nara, H. Torii and M. Tasumi, J. Phys. Chem.,
100 (1996) 19812.
5 E. Dagotto, Physics World, April, 22-23, 1996.
6 M. Verdaguer, Polyhedron, 20 (2001) 1115.
7 J. S. Miller and J. Epstein, Angew. Chem., Int. Ed. Engl.,
33 (1994) 385.
37 F. H. Allen, Acta Cryst., B58 (2002) 380.
38 I. Krstanovic, L. Karanovic, D. Stojakovic and L. Golic,
Cryst. Struct. Commun., 11 (1982) 1747.
39 H. Icbudak, H. Olmez, O. Z. Yesilel, F. Arslan,
P. Naumov, G. Jovanovski, A. R. Ibrahim, A. Usman,
H.-K. Fun, S. Chantrapromma and S. W. Ng, J. Mol.
Struct., 657 (2003) 255.
8 S. Meenakumari and A. R. Chakravarty, Polyhedron,
12 (1993) 1825.
9 F. D. Rochon, R. Melanson and M. Andruh, Polyhedron,
15 (1996) 3075.
10 S. Meenakumari, S. K. Tiwari and A. R. Chakravarty,
J. Chem. Soc., Dalton Trans., 1993, 2175.
11 S. Perlepes, J. C. Huffman and G. Christou, Polyhedron,
14 (1995) 1073.
40 D. Mikloš, P. Segl’a, M. Palicova, M. Kopcova,
M. Melnik, M. Valko, T. Glowiak, M. Korabik and J.
Mrozinski, Polyhedron, 20 (2001) 1867.
41 V. Kh. Sabirov, M. A. Azizov, A. A. Shabilalov,
Yu.T. Struchkov and G. G. Aleksandrov, Koord. Khim.,
8 (1982) 245.
12 M. Melnik and R. Nasanen, Suom. Kemistilehti,
B43 (1970) 99.
13 H. Oshio and U. Nagashima, Inorg. Chem.,
31 (1992) 3295.
42 P. Segl’a, M. Palicová, M. Koman, D. Mikloš and
M. Melník, Inorg. Chem. Commun., 3 (2000) 120.
J. Therm. Anal. Cal., 82, 2005
753

ZELE+ÁK et al.
43 L. A. Kovbasyuk, I. O. Fritsky, V. N. Kokozay and
T. S. Iskenderov, Polyhedron, 16 (1997) 1723.
44 M. R. Sundberg, H. Tylli, J. Matikainen, T. Book,
R. Uggla and M. Valkeapaa, Inorg. Chim. Acta,
266 (1997) 47.
48 M. R. Sundberg and M. Klinga, Polyhedron,
13 (1994) 1099.
49 A. Y. Obaid, A. O. Alyoubi, A. A. Samarkandy,
S. A. Al-Thabaiti, S. S. Al-Juaid, A. A. El-Bellihi and
El-H. M. Deifallah, J. Therm. Anal. Cal., 61 (2000) 985
and references therein.
45 R. Sillanpaa, J. Jokela and M. R. Sundberg, Inorg. Chim.
Acta, 258 (1997) 221.
46 M. R. Sundberg, J. K. Koskimies, J. Matikainen and
H. Tylli, Inorg. Chim. Acta, 268 (1998) 21.
47 M. R. Sundberg, R. Kivekas, P. Huovilainen and
R. Uggla, Inorg. Chim. Acta, 324 (2001) 212.
DOI: 10.1007/s10973-005-6863-9
754
J. Therm. Anal. Cal., 82, 2005