Thermal behavior of some new triazole derivative complexes

Article abstract of DOI:10.1007/s10973-007-8766-4

A series of new complexes with mixed ligands of the type [ML(C ₃H₃O₂)₂]?nH₂O (((1) M=Mn, n=1; (2) M=Co(II), n=2; (3) M=Ni(II), n=4; (4) M=Cu(II), n=1.5; (5) M=Zn(II), n=0; L=3-amino-1,2,4-triazole and (C₃H₃O ₂)=acrylate anion) were synthesized and characterised by chemical analysis and IR data. In all complexes the 3-amino-1,2,4-triazole acts as bridge while the acrylate acts as bidentate ligand except for complex (5) where it is found as unidentate. The thermal behaviour steps were investigated in nitrogen flow. The thermal transformations are complex processes according to TG and DTG curves including dehydration, acrylate ion and 3-amino-1,2,4-triazole degradation respectively. The final products of decomposition are the most stable metal oxides, except for complex (4) that leads to metallic copper.

Full text of DOI:10.1007/s10973-007-8766-4

Journal of Thermal Analysis and Calorimetry, Vol. 92 (2008) 1, 209–214
THERMAL BEHAVIOR OF SOME NEW TRIAZOLE DERIVATIVE
COMPLEXES
1
Mihaela Badea , Rodica Olar , Dana Marinescu and Gina Vasile
*
1
1
2
1
University of Bucharest, Faculty of Chemistry, Department of Inorganic Chemistry, 90-92 Panduri St., 050663 Sector 5
Bucharest, Romania
University of Agronomical Sciences and Veterinary Medicine, Department of Agrochemistry, Bd. Marasti 59
2
Bucharest, Romania
A series of new complexes with mixed ligands of the type [ML(C
3
H
3
O
2
)
n=4; (4) M=Cu(II), n=1.5; (5) M=Zn(II), n=0; L=3-amino-1,2,4-triazole and (C
2
]×nH
2
O ((1) M=Mn, n=1; (2) M=Co(II), n=2; (3) M=Ni(II),
)=acrylate anion) were synthesized and char-
3
3 2
H O
acterised by chemical analysis and IR data. In all complexes the 3-amino-1,2,4-triazole acts as bridge while the acrylate acts as
bidentate ligand except for complex (5) where it is found as unidentate. The thermal behaviour steps were investigated in nitrogen
flow. The thermal transformations are complex processes according to TG and DTG curves including dehydration, acrylate ion and
3-amino-1,2,4-triazole degradation respectively. The final products of decomposition are the most stable metal oxides, except for
complex (4) that leads to metallic copper.
Keywords: acrylate, 3-amino-1,2,4-triazole, carbonate, complexes, thermal stability
Introduction
ands have been synthesized and characterized. These
compounds were obtained from the reaction of the metal
acrylate with 3-amino-1,2,4-triazole. The complexes
were formulated on the basis of analytical and spectral
data as: [ML(C H O ) ]×nH O ((1) M=Mn(II), n=1;
Finding new species, with a wide spectrum of biologi-
cal activity (antimicrobial, antiviral) and also low
cytotoxicity represents a very important aspect in the
biochemical research area. This is due to the fact that
the pathogen agents continuously undergo mutations
and also the drugs used to treat the viral diseases de-
velop in time a certain tolerance, while in some cases
the use of these can lead to toxic effects.
One of our research directions is to obtain complex
species of biocations that possess bioactive ligands and
polymerizable functional groups designed to obtain
products with antiseptic and anti-infectious activity.
The selection of acrylate ion as ligand was gen-
erated by their multiple uses such as excipients for
different drugs and for obtaining prostetic devices
used in biomedicine (urinary catheters, central vein
catheters, cardiac valves, stomatologic materi-
als) [1–4]. Moreover, the chemistry of 1,2,4-triazole
derivatives has also received much attention because
of their significant biologic activities [5].
3
3
2 2
2
(2) M=C(II), n=2; (3) M=Ni(II), n=4; (4) M=Cu(II),
n=1.5; (5) M=Zn(II), n=0; L=3-amino-1,2,4-triazole and
(C H O )=acrylate anion).
3
3
2
The thermal behaviour provided confirmation of
the complexes composition as well as the number and
the nature of water molecules and the intervals of
thermal stability. The thermal transformations are
complex processes according to TG and DTA curves
including dehydration, acrylate ion as well as
3-amino-1,2,4-triazole thermolysis. The products of
decomposition are the metal oxides except for com-
plex (4) that generates metallic copper.
Experimental
All chemicals were purchased from Aldrich and
Merck, reagent grade and were used without further
purification.
Besides having herbicidal activity [6], 2-amino-
,3,4-triazole has been found as inhibitor for enzy-
1
matic processes [7–9]. From coordinative point of
view, it has been evidenced that 3-amino-1,2,4-triazole
can act as monodentate [10] as well as bridge through
the two [11, 12] or three nitrogen atoms of the triazole
ring [13] as well as through all nitrogen atoms [14].
In order to modulate biological properties of
acrylate complexes, five new complexes with mixed lig-
Synthesis of the complexes
Complex [MnL(C H O ) ]×H O (1): 0.197 g of
3
3
2 2
2
manganese acrylate were dissolved by stirring in
a 15 mL mixture water:ethanol (1:2 v/v). To the
colourless obtained solution was added under
*
Author for correspondence: e_m_badea@yahoo.com, badea.elena@unibuc.ro
1
388–6150/$20.00
2008 Akadémiai Kiadó, Budapest
Akadémiai Kiadó, Budapest, Hungary
Springer, Dordrecht, The Netherlands
©

BADEA et al.
continuous stirring 0.084 g of 3-amino-1,2,4-
n
C=N, 1640s;
C–N,1222m; nN–N, 1065m, 989m.
Complex [ZnL(C )] (5): 0.207 g of zinc acrylate
n
as(COO), 1549vs;
ns(COO), 1356m;
triazole (L). There was no colour modification. The
reaction mixture was stirred 1 h. The obtained
solution was left to stand at room temperature for
several days. The white microcrystals obtained were
filtered off, washed with ethylic alcohol and air-dried.
Analysis, found: Mn, 18.27; C, 32.24; H, 3.87;
n
H O
3 2
3
was dissolved under continuous stirring in 15 mL
mixture water:ethanol (1:2 v/v). To the opalescent
obtained solution was added 0.084 g of 3-amino-
1,2,4-triazole (L). It was obtained immediately a
white precipitate. The reaction mixture was stirred
for 30 min. The precipitate was filtered off, washed
with ethylic alcohol and air-dried. Analysis, found:
Zn, 22.35; C, 32.82; H, 3.32; N, 19.35%; calculated
for ZnC H N O : Zn, 22.42; C, 32.96; H, 3.46;
N, 18.86%; calculated for MnC
C, 32.12; H, 4.04; N, 18.73%; IR (KBr pellet), cm :
nH2 O , 3450sh; nas(NH 2 ) , 3410sh; ns(NH 2 ) , 3355s; nNH
214sh, 3073m; nas(COO), 1540vs; nC=N, 1646vs;
8 12 4 5
H N O : Mn, 18.36;
–
1
,
3
n
s(COO), 1363m; nC–N,1214m; nN–N, 1054m, 986m.
Complex [CoL(C H O )]×2H O (2): 0.236 g of
8
10
4
4
–
1
N, 19.22%; IR (KBr pellet), cm : n , 3400sh;
as(NH 2 )
3
3
2
2
cobalt acrylate were dissolved under continuous
stirring in 15 mL mixture water: ethanol (1:2 v/v). To
the pale violet solution 0.084 g of 3-amino-1,2,4-
triazole (L) was added. The colour of the reaction
mixture turns rapidly to dark reddish and a precipitate
was obtained. The reaction mixture was stirred for
ns(NH 2 ) , 3365s; n , 3210m, 3050sh; nC=N, 1644s;
NH
n
as(COO), 1573vs; ns(COO), 1357m; nC–N, 1224m; nN–N,
1069m, 984m.
Methods
1
h. The reddish precipitate was filtered off, washed
The chemical analysis and IR spectral data were used
in order to confirm the nature of some intermediates
and also the final products. Chemical analysis of
carbon and nitrogen has been performed using an
EA 1110 analyzer. Manganese, cobalt, nickel and zinc
were determined gravimetrically in the laboratories of
Inorganic Chemistry Department. Copper was deter-
mined volumetrically using the iodometry method. All
the chemical analyses were performed on the air-dried
compounds without heating to constant mass.
with ethylic alcohol and air-dried. Analysis, found:
Co, 18.22; C, 29.98; H, 4.25; N, 17.55%; calculated
for CoC H N O : Co, 18.35; C, 29.92; H, 4.39;
8 14 4 6
–
1
N, 17.44%; IR (KBr pellet), cm : n , 3460sh;
H2 O
nas(NH 2 ) , 3420sh; ns(NH 2 ) , 3333s; nNH, 3210sh, 3065sh;
n
as(COO),1538vs;
n
C=N,1620vs;
n
,
1361m;
Complex [NiL(C H O )]×4H O (3): 0.236 g of
3 3 2 2
s(COO)
n
(C–N),1226m; n(N–N), 1059m, 993m.
nickel acrylate was dissolved by stirring in 15 mL
mixture water:ethanol (1:2 v/v). At the pale green
solution 0.084 g of 3-amino-1,2,4-triazole (L) were
added and the colour turns in turquoise. The solution
was stirred for one hour and was left to stand at room
temperature for several days. The obtained pale blue
compound was filtered off, washed with ethylic
alcohol and air-dried. Analysis, found: Ni, 16.34;
C, 26.78; H, 4.88; N, 15.86%; calculated for
IR spectra were recorded in KBr pellets with a
–1
Bio-Rad FTIR 135 spectrometer in the 400–4000 cm
range.
The heating curves (TG, DTA and DTG) were re-
corded using a Labsys 1200 Setaram instrument, with a
sample mass of 6–27 mg over the temperature range
–1
of 20–1000°C, using a heating rate of 10 K min . The
measurements were carried out in a nitrogen atmosphere
3 –1
(flow rate 20 cm min ) by using alumina crucibles.
NiC O
N, 15.70%; IR (KBr pellet), cm : n , 3550sh;
H
N
: Ni, 16.48; C, 26.92; H, 5.08;
–
8
18
4
8
1
H2 O
nas(NH 2 ) , 3400sh; ns(NH 2 ) , 3328s; nNH, 3255sh, 3090sh;
n
C=N, 1542s; nas(COO), 1546vs; ns(COO), 1362m;
C–N,1213m; nN–N, 1063m, 990m.
Complex [CuL(C H O )]×1.5H O (4): 0.223 g of
Results and discussion
n
Physico-chemical characterization of complexes
3
3
2
2
copper acrylate was dissolved by stirring in 15 mL
mixture water:ethanol (1:2 v/v). An amount of 0.084 g
of 3-amino-1,2,4-triazole (L) was added under
continuous stirring to the blue copper acrylate solution.
The colour of reaction mixture turns rapidly to
turquoise. The mixture was stirred for 1 h. The dark
green precipitate was filtered off, washed with ethylic
alcohol and air-dried. Analysis, found: Cu, 19.87;
C, 30.27; H, 4.01; N, 17.75%; calculated for
In this paper, we report the preparation and physico-
chemical characterisation of some complexes with
acrylate and 3-amino-1,2,4-triazole. The major goal
of this paper was to evidence the thermal behaviour,
in nitrogen flow, of these complexes that could be
used as intermediate for obtaining some polymer
metal containing species. The complexes have been
formulated on the basis of chemical analysis and IR
spectra as it follows:
CuC H N O5.5: Cu, 20.06; C, 30.33; H, 4.14;
8 13 4
–1
N, 17.69%; IR (KBr pellet), cm : n , 3480sh;
nas(NH 2 ) , 3419s; ns(NH 2 ) , 3340sh; nNH, 3210sh, 3060sh;
[Mn(C
Co(C
2
H
4
N
4
)(C
3
H
3
O
2
)
2
]×H
2
O
(1)
(2)
H2 O
[
2
H
4
N
4
)(C
3
H
3
O
2
)
2
]×2H
O
2
210
J. Therm. Anal. Cal., 92, 2008

SOME NEW TRIAZOLE DERIVATIVE COMPLEXES
Fig. 1 The proposed coordination for complexes; M=Mn, Co, Ni, Cu
[
Ni(C H N )(C H O ) ]×4H O
2
(3)
(4)
(5)
2
4
4
3
3
2 2
[
Cu(C H N )(C H O ) ]×1.5H O
2 4 4 3 3 2 2 2
[
Zn(C H N )(C H O ) ]
2 4 4 3 3 2 2
These compounds were obtained from the reaction
of the corresponding metal acrylate with 3-amino-
1,2,4-triazole. In order to maintain the molar ratio metal
ion : amine (1:1), a lower amine quantity was used.
In all complexes the 3-amino-1,2,4-triazole acts
as bridge while the acrylate acts as bidentate ligand ex-
cept for complex (5) where it is found as unidentate.
In the IR spectra of complexes are viewed the
characteristic patterns of 3-amino-1,2,4-triazole (ex-
perimental part) that generate bands characteristic for
Fig. 2 TG and DTA curves of [Mn(C H N )(C H O ) ]×
2
4
4
3
3
2 2
H O (1)
2
–
1
amine group in the 3000–3400 cm range. At about
–
640 cm a very strong band for all complexes is as-
1
1
signed to nC=N vibrations. In the 3-amino-1,2,4-tria-
Thermal decomposition of [Mn(C H N )(C H O ) ]×H O
2
4
4
3
3
2 2
2
–
1
zole spectrum two bands appear at 1048 and 969 cm
The TG and DTA curves corresponding to the com-
plex (1) heated in the 20–900°C temperature range
are presented in Fig. 2 and indicate that decomposi-
tion follows four steps.
The first step of compound transformation consists
in an endothermic elimination of water molecules
assigned to nN–N vibration mode. For all complexes
these bands are shifted to higher wave numbers indi-
cating that this ligand acts as bridge.
The characteristic bands assigned to the acrylate
fragment (nas(COO) and ns(COO)) can be identified also in
all complexes spectra. It is known that the D=
(Table 1). Considering that the IR spectrum indicates
n
as(COO)–ns(COO) value is an indication of the coordina-
tion mode associated with this anion [15]. Thus, the
clearly the bidentate nature of acrylate results that the
water molecules are uncoordinated. On this basis it is
surprising that they are eliminated at so high tempera-
tures. This behaviour could indicate that these mole-
cules are involved in strong hydrogen interactions with
the acrylate, as it was also observed in the case of other
acrylate complexes previously reported [17, 18]. The
second step, endothermic, is not a single one being an
overlap of at least two processes as both TG and DTA
curves indicate. This step corresponds to the release of
the amino group from 3-amino-1,2,4-triazole as well as
to acrylate into carbonate transformation. This behav-
iour at heating of the coordinated 2-amino-1,2,4-triazole
was already observed for other complexes bearing this
ligand [13]. Next step, endothermic also, corresponds to
–
1
D value of 216 cm in the case of compound (5) indi-
cates the unidentate coordination mode while the
lower difference for other complexes is correlated
with the presence of this ligand as bidentate [16]. The
presence of water molecule in complexes generates
–
1
the appearance of a large band about 3500 cm as-
signed to nOH stretching vibrations [16].
On the basis of the above data the proposed coor-
dination for the complexes is as it follows (Fig. 1):
Thermal behavior of complexes
The main objective of this paper was to analyse the
thermal behaviour of the complexes in order to ac-
quire a polymeric fashion for them.
The results concerning the thermal degradation
of the new complexes are presented as it follows.
1,2,4-triazole ring loss according to TG curve. The re-
sulted intermediate, MnCO
, was isolated and character-
3
ized using elemental analysis and IR spectrum (Fig. 3).
The intermediate at 840°C displays bands characteristic
of bidentate carbonate ion: 1605 (n ) 1030 (n2(CO3)
)
and 760 cm (n3(CO3) ) [16]. Moreover, the chemical
1(CO3)
–1
J. Therm. Anal. Cal., 92, 2008
211

BADEA et al.
212
J. Therm. Anal. Cal., 92, 2008

SOME NEW TRIAZOLE DERIVATIVE COMPLEXES
Fig. 3 IR spectrum of the carbonate intermediate resulted
at 840°C from thermal degradation of complex (1)
composition corresponds to a minimal formula MnCO3
(%calc./exp., Mn, 47.79/47.98; C, 10.45/10.24).
2 4 4 3 3 2 2
Fig. 4 TG and DTA curves of [Zn(C H N )(C H O ) ] (5)
MnCO turns in Mn O in the last step, process
3
2
3
accompanied by a strong exothermic effect (found/
calcd. overall mass loss: 73.69/73.60).
duct is metallic copper (found/calcd. overall mass
loss: 79.84/79.93).
Thermal decomposition of [Co(C
2
H
4
N
4
)(C
3
H
3
O
2
)
2
]×2H
O
2
Thermal decomposition of [Zn(C H N )(C H O ) ]
2
4
4
3
3
2 4
Complex (2) loses the crystallization water in
the 50–150°C range. The second step, similar with
that observed for (1) occurs with amino group release
and acrylate into carbonate transformation, but the
two processes seem to be better evidenced for com-
pound (2). In the third step the complex intermediate
The anhydrous nature of compound (5) complex is re-
vealed by the fact that decomposition starts up
to 250°C. The thermal decomposition (Fig. 4) begins
with the amine group release followed by the acrylate
degradation. The remaining triazole ring is eliminated
in the second step. The third step, exothermic one,
corresponds to carbonate transformation into oxide
(found/calcd. overall mass loss: 71.77/72.08).
leads to 6CoCO
elimination and partially decomposition of CoCO
The remaining CoCO generates Co O as final resi-
3 3 4
×Co O as a result of the triazole ring
.
3
3
3
4
due (found/calcd. overall mass loss: 74.89/75.01).
Conclusions
Thermal decomposition of [Ni(C
H N )(C H O ) ]×4H O
2 4 4 3 3 2 2 2
The new complex compounds of Mn(II), Co(II),
Ni(II), Cu(II) and Zn(II) with mixed ligands
(3-amino-1,2,4-triazole and acrylate) belong to a
class of coordination compounds of current interest
having into its composition a ligand which could be
involved in polymerisation processes.
Except for complex (5) where acrylate acts as
monodentate, for other complexes this ion acts as
bidentate according to IR data. The 3-amino-1,2,4-
triazole function as bridge for all complexes.
Thermal analysis (TG, DTA) of these complexes
elucidated the composition and also the number and
nature of the water molecules. Except for complex (3)
the amino group release was observed in the second
step. It was also evidenced the existence of an inter-
mediate step corresponding to the formation of metal
carbonates for all compounds.
According to the TG profile the decomposition of
[
Ni(C )(C ]×4H O (3) occurs in three,
well-defined steps (found/calcd. overall mass loss:
8.93/79.06). After water loss in the 55–220°C range,
2
H
4
N
4
3
H
3
O
2
)
2
2
7
the 3-amino-1,2,4-triazole elimination as well as
acrylate into carbonate transformation occur in the
second step. Unlike the other species of this type for
Ni(II) complex the elimination of the amino group
and triazole ring respectively are not delimited. The
carbonate leads to NiO in the final step according to
the mass variation.
Thermal decomposition of
[Cu(C H N )(C H O ) ]×1.5H O
2 4 4 3 3 2 4 2
The decomposition of complex (4) comprises also
three steps and starts with water elimination, process
that also occurs at high temperatures. The anhydrous
species releases then the amine group and the acrylate
ion turns into carbonate. The next step is a very com-
plex one and consists in triazole ring elimination and
carbonate decomposition respectively. The final pro-
Acknowledgements
This work was partially supported by the VIASAN grant
nr. 142/2006 of the Romanian Ministry of Education and Re-
search.
J. Therm. Anal. Cal., 92, 2008
213

BADEA et al.
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