Synthesis, characterization and thermal studies on solid compounds of 2-chlorobenzylidenepyruvate of heavier trivalent lanthanides and yttrium(III)

Article abstract of DOI:10.1007/s70973-005-6972-y

Solid-state compounds of general formula LnL_3· nH ₂O, where Ln represents heavier lanthanides and yttrium and L is 2-chlorobenzylidenepyruvate, have been synthesized. Chemical analysis, simultaneous thermogravimetry-differential anal

Full text of DOI:10.1007/s70973-005-6972-y

Journal of Thermal Analysis and Calorimetry, Vol. 83 (2006) 1, 233–240
SYNTHESIS, CHARACTERIZATION AND THERMAL STUDIES ON
SOLID COMPOUNDS OF 2-CHLOROBENZYLIDENEPYRUVATE OF
HEAVIER TRIVALENT LANTHANIDES AND YTTRIUM(III)
1
G. Bannach , E. Schnitzler , O. Treu Filho , V. H. S. Utuni and M. Ionashiro
2
1
1
1*
1
Instituto de Química UNESP, Araraquara SP, CP 355, CEP 14801-970, Brazil
2
Departamento de Química, UEPG, 84030-000 Ponta Grossa, PR, Brasil
Solid-state compounds of general formula LnL
-chlorobenzylidenepyruvate, have been synthesized. Chemical analysis, simultaneous thermogravimetry-differential analysis
TG-DTA), differential scanning calorimetry (DSC), X-ray powder diffractometry, elemental analysis and infrared spectroscopy
3
2
⋅nH O, where Ln represents heavier lanthanides and yttrium and L is
2
(
have been employed to characterize and to study the thermal behaviour of these compounds in dynamic air atmosphere.
On heating these compounds decompose in four (Gd, Tb, Ho to Lu, Y) or five (Eu, Dy) steps. They lose the hydration water in
the first step and the thermal decomposition of the anhydrous compounds up to 1200°C occurs with the formation of the respective
4 7 2 3
oxide, Tb O and Ln O (Ln=Eu, Gd, Dy to Lu and Y) as final residue. The dehydration enthalpies found for these compounds (Eu,
–1
to Lu and Y) were: 65.77, 55.63, 86.89, 121.65, 99.80, 109.59, 131.02, 119.78, 205.46 and 83.11 kJ mol , respectively.
Keywords: benzylidenepyruvate, rare earth, thermal behaviour
Introduction
thermogravimetry and differential thermal analysis
TG-DTA). The data obtained allowed us to acquire
(
Synthesis of benzylidenepyruvic acid (HBP), as well
as of phenyl-substituted derivatives of HBP, has been
reported [1, 2]. These acids are of continuing interest
as intermediates in pharmacological, industrial and
chemical syntheses, in the development of enzyme
inhibitors and drugs, as model substrates of enzymes,
and in other ways [3–7].
information concerning these compounds in the
solid-state, including their thermal behaviour and
thermal decomposition.
Experimental
Preparation and investigation of several metal-ion
complexes of phenyl-substituted derivatives of BP,
have been carried out in aqueous solutions [8–10], and
in solid-state [11–19]. In aqueous solutions these
works reported mainly the thermodynamic stability
Sodium 2-chlorobenzylidenepyruvate and its corre-
sponding acid were synthesized following the same
procedure described in the literature [17], with some
modification as follows: an aqueous solution of so-
dium pyruvate (22 g per 50 mL) was added with con-
tinuous stirring, to 24 mL of 2-chlorobenzaldehyde
(29 g). Sixty milliliters of an aqueous sodium hydrox-
ide solution (18 m/v%) was slowly added while the re-
acting system was stirred and cooled in an ice-bath.
The rate of addition of alkali was regulated so that the
temperature remained between 5 and 9°C. The forma-
tion of a pale yellow precipitate was observed during
the addition of the sodium hydroxide solution.
(
β ) and spectroscopic parameters (ε1max, λmax), associ-
1
ated with 1:1 complex species, analytical applications
of the ligands, e.g., in gravimetric analysis and as
metallochromic indicators, while in the solid-state, the
establishment of the stoichiometry and detailed knowl-
edge of the thermal behaviour of the ligands and their
metal ion compounds have been the main purposes of
these studies.
In the present paper, ligand and solid-state com-
pounds of heavier trivalent lanthanides and yt-
The system is left to stand for about 3 h at room
temperature (23–28°C). The pale yellow precipitate
(impure sodium 2-chlorobenzylidenepyruvate) is fil-
tered, washed with five 100 mL portions of methanol,
to remove most of the unreacted aldehyde and second-
ary products. The crude product was dissolved in water
(500 mL) and aldehyde yet present as contaminating
was removed through a separator funnel.
trium(III) with
-Cl–C H –CH=CH–CO–COO , were synthesized.
6 4
2-chlorobenzylidenepyruvate,
–
2
The compounds were investigated by means of chem-
ical analysis, X-ray powder diffractometry, elemental
analysis (E. A.), infrared spectroscopy, differential
scanning calorimetry (DSC) and simultaneous
*
Author for correspondence: massaoi@iq.unesp.br
1
388–6150/$20.00
Akadémiai Kiadó, Budapest, Hungary
Springer, Dordrecht, The Netherlands
©
2006 Akadémiai Kiadó, Budapest

BANNACH et al.
In the sodium 2-chlorobenzylidenepyruvate solu-
tion was added under continuous stirring, concentrated
Simultaneous TG-DTA curves were obtained
with thermal analysis system, model SDT 2960, from
TA Instruments. The purge gas was an air flow
–1
(12 mol L ) hydrochloric acid until total precipitation
–
1
–1
of the 2-chlorobenzylidenepyruvic acid (12.3 g).
of 100 mL min . A heating rate of 20°C min was
adopted, with samples weighing about 9 mg. Alumina
crucible, was used for TG-DTA curves.
–
1
Aqueous solution of Na2-Cl-BP, 0.1 mol L was
prepared by direct weighing of the salt. Lanthanide
chlorides were prepared from the corresponding metal
oxides (except for yttrium) by treatment with concen-
trated hydrochloric acid. The residues were dissolved in
distilled water, transferred to a volumetric flask and di-
The DSC curves were obtained using a Mett-
ler TA-4000 thermal analysis system with an air flux
–1
–1
of 100 mL min , a heating rate of 20°C min and with
samples weighing about 5 mg. Aluminium crucible
with perforated cover was used for DSC curves.
The final thermal decomposition residues up
to 580°C (Eu, Yb); 550°C (Gd, Tb, Dy, Tm); 530°C
(Ho, Lu, Y) and 520°C (Er) were characterized by
X-ray powder diffractometry.
–1
luted in order to obtain ca. 0.1 mol L solutions, whose
pH were adjusted to 5.0 by adding diluted sodium hy-
droxide or hydrochloric acid solutions. Yttrium(III) was
–1
used as its chloride and 0.1 mol L aqueous solutions of
this ion were prepared by direct weighing of the salt.
The solid-state compounds Ln(2-Cl-BP) (Ln=
3
lanthanides or yttrium) were prepared by adding
slowly, with continuous stirring, the solutions of the
ligand to the respective metal chloride solutions, until
total precipitation of the metal ions. The precipitates
were washed with distilled water until elimination of
the chloride ions, filtered through and dried on
Whatman n° 42 filter paper, and kept in a desiccator
over anhydrous calcium chloride.
Computational strategy
For calculation of theoretical infrared spectrum of yt-
trium 2-chlorobenzylidenepyruvate it is necessary to
evaluate the structure and wave function computed by
the ab initio SCF Hartree–Fock–Roothan method [21]
using a split valence (3–21 g*) basis set [22]. The per-
formed molecular calculations in this work were done
by using the Gaussian 98 routine [23] and the hardware
used is the IBM power 3. The crystal geometry of yt-
trium 2-chlorobenzylidenepyruvate is unknown. The
geometry optimization was carried out without any con-
straints. The molecule of 2-chlorobenzylidenepyruvate
contain rings with conformational flexibility, all vari-
ables were optimized. The optimization proceeded more
uniformly when all variables were optimized.
In solid-state compounds, hydration water,
ligand and metal contents were determined from the
TG curves. The metal ions were also determined by
complexometric titrations with standard EDTA solu-
tions, using xylenol orange as indicator [20].
X-ray powder patterns were obtained by using a
Siemens D-5000 X-ray diffractometer, employing CuK
α
radiations (λ=1.541 ) and setting of 40 kV and 20 mA.
Infrared spectra for 2-Cl-BP (sodium salt) as
well as for its trivalent lanthanide compounds were
run on a Nicolet mod. Impact 400 FTIR instruments,
Results and discussion
–
1
within 4000–400 cm range. The solid samples were
The analytical results of the synthesized compounds
are shown in Table 1. These data permitted to establish
the stoichiometry of the compounds, which is in agree-
ment with general formula Ln(2-Cl-BP) ⋅nH O, where
pressed into KBr pellets.
Carbon and hydrogen contents were determined by
microanalytical procedures, with an EA 1110 CHNS-O
Elemental Analyzer from CE Instruments.
3
2
Table 1 Analytical data for Ln(L)
3
⋅nH
L. lost/%
theor. TG
2
O
Water/%
Metal/%
TG
Δm total/%
EDTA theor. TG
Carbon/%
Hydrogen/%
Compound
theor.
TG
theor.
theor. E.A. theor. E.A.
Eu(L)
3
⋅2H
⋅2H
⋅2H
2
O
4.41
4.38
4.37
2.23
6.36
6.36
6.35
6.32
6.30
4.78
4.32 74.05 74.04 18.60 18.69
4.35 73.57 73.46 19.13 19.25
4.26 72.94 73.25 19.29 19.12
2.41 74.73 74.45 20.08 20.16
6.25 71.36 71.70 19.45 19.25
6.22 71.14 71.31 19.67 19.65
6.59 71.00 70.82 19.83 19.78
6.25 70.66 71.02 20.22 19.96
6.20 70.51 70.63 20.40 20.38
4.56 80.24 79.97 11.79 12.18
19.03
19.06
19.19
20.37
19.33
19.38
19.84
20.22
20.37
11.66
78.46 78.36 44.11 44.93 2.72
77.95 77.81 43.83 44.65 2.70
77.31 77.51 43.74 43.51 2.70
76.96 76.86 44.52 44.71 2.50
77.72 77.95 42.50 42.25 2.86
77.50 77.53 42.38 42.60 2.85
77.35 77.41 42.30 41.64 2.85
76.98 77.27 42.09 41.90 2.83
76.81 76.83 42.00 41.75 2.83
85.02 84.53 47.80 48.64 2.95
3.03
2.83
2.61
2.87
2.70
2.55
2.78
2.69
2.74
2.66
Gd(L)
3
2
O
Tb(L)
Dy(L)
Ho(L)
3
2
O
3
⋅H
2
O
3
⋅3H
2
O
Er(L)
Tm(L)
Yb(L)
Lu(L)
3
⋅3H
⋅3H
⋅3H
⋅3H
⋅2H
2
O
3
2
O
3
2
O
3
2
O
Y(L)
3
2
O
Ln=lanthanides, L=2-chlorobenzylidenepyruvate
234
J. Therm. Anal. Cal., 83, 2006

2-CHLOROBENZYLIDENEPYRUVATE OF HEAVIER TRIVALENT LANTHANIDES AND YTTRIUM(III)
Table 2 IR spectroscopic data for sodium 2-chlorobenzylidene-
pyruvate and for its compounds with heavier trivalent
lanthanides
Compound
ν
O–H
H
2
O
νs(COO )
–
νas(COO )
–
ν
C=O
NaL⋅1.5H
Eu(L)
⋅2H
Gd(L)
⋅2H
⋅2H
2
O
3443 m
3448 m
3369 m
3385 m
3443 m
3391 m
3369 m
3387 m
3377 m
3394 m
3477 m
1402 m
1433 m
1427 m
1431 m
1431 m
1441 m
1441 m
1431 m
1431 m
1441 m
1429 m
1615 s
1589 s
1589 s
1589 s
1589 s
1585 s
1585 s
1587 s
1587 s
1585 s
1589 s
1682 s
1634 s
1645 s
1651 s
1645 s
1650 s
1651 s
1651 s
1653 s
1651 s
1647 s
3
2
O
3
2
O
Tb(L)
Dy(L)
Ho(L)
3
2
O
3
⋅H
2
O
3
⋅3H
2
O
Er(L)
Tm(L)
Yb(L)
Lu(L)
Y(L)
⋅2H
3
⋅3H
⋅3H
⋅3H
⋅3H
2
O
3
2
O
3
2
O
3
2
O
3
2
O
L=2-chlorobenzylidenepyruvate; s – strong, m – medium,
as(O–H) – hydroxyl group stretching frequency; νs(COO and
ν
–
)
νas(COO
–
– symmetrical and anti-symmetrical vibrations of
)
–
the COO structure; νs(C=O) – ketonic carbonyl stretching
frequency
Table 3 Theoretical geometries parameters of yttrium(III)
with 2-chlorobenzylidenepyruvate
d O–Y
2.17 
2.36 
1.29 
1.21 
1.24 
1.75 
d =O–Y
d C–O
d YOC=O
d C=O
d C–Cl
<
<
<
<
<
O–Y–O
Y–O–C
Y–O=C
O–C–C
O=C–C
67.71°
Fig. 1 Proposed structure a – 3D and b – 2D of solid-state com-
pound yttrium(III) with 2-chlorobenzylidenepyruvate
was 3D optimized using Hartree–Fock–Roothan method,
split-valence (3–21 g*) basis set of Gaussian 98
128.43°
120.18°
109.25°
114.42°
–1
615 cm (anti-symmetrical carboxylate vibration)
1
d – distance, < – means angle
are both shifted to lower frequencies in the com-
–
1
pounds, namely, 1634–1651 and 1585–1589 cm , re-
spectively, suggesting lanthanides coordination by
the α-ketonic carbonyl and carboxylate groups of the
ligand [24, 25]. This behaviour is in agreement with
4-Me-BP compounds with the same metal ions [15].
The theoretical infrared spectrum of the
Ln represents heavier lanthanides (Eu to Lu and Y),
-Cl-BP is 2-chlorobenzylidenepyruvate and n=1
Dy), 2 (Eu, Gd, Tb, Y), 3 (Ho, Er, Tm, Yb, Lu).
X-ray powder patterns showed that all the com-
2
(
pounds were obtained in amorphous state. The amor-
phous state is undoubtedly related to the low solubility
of these compounds, as already observed for lanthanides
and yttrium compounds with DMBP [12] and heavier
lanthanides and yttrium compounds with 4-MeO-BP
and 4-Cl-BP [11, 14].
Y(L)
3
⋅3H O was calculated by using a harmonic
2
field [26] and the obtained frequencies were not scaled.
The geometry optimization was computed by the opti-
mized algorithm of Berny [27]. The obtained geometry
from calculations is presented in Fig. 1 and Table 3.
The theoretical infrared spectrum (electronic
Infrared spectroscopic data on 2-chlorobenzyl-
idenepyruvate (sodium salt) and its compounds with
heavier trivalent lanthanides are shown in Table 2.
The bands found for 2-Cl-BP (sodium salt) centered
1
–1
state A) was obtained with frequency values (cm ),
relative intensities, assignments and description of
vibrational modes.
–
1
at 1682 cm (ketonic carbonyl stretching) and
J. Therm. Anal. Cal., 83, 2006
235

BANNACH et al.
Fig. 2 Simultaneous TG-DTA and TG-DTG curves of the compounds: a – Eu(2-Cl-BP)
3
⋅2H
2
O (m =8.871 mg),
i
b – Dy(2-Cl-BP)
e – Lu(2-Cl-BP)
3
⋅H
⋅3H
2
O (10.397 mg), c – Gd(2-Cl-BP)
O (9.714 mg)
3
⋅2H
2
O (8.821 mg), d – Ho(2-Cl-BP)
3
⋅3H O (9.159 mg) and
2
3
2
A comparative analysis between the experimental
and theoretical spectrum shows the following conclu-
sions: (a) the first assignment shows a strong contribu-
while the theoretical results show the corresponding
–1
peak at 1737 cm with discrepancies +5.46%. (b) The
second assignment shows a strong contribution at
–1
tion at 1647 cm suggesting an ν(C=O) of carbonyl,
236
J. Therm. Anal. Cal., 83, 2006

2-CHLOROBENZYLIDENEPYRUVATE OF HEAVIER TRIVALENT LANTHANIDES AND YTTRIUM(III)
Table 4 Temperature ranges θ, mass losses and peak temperatures observed for each step of the TG-DTA curves of the
compounds
Steps
Compound
first
second
third
fourth
fifth
θ°C
loss/%
30–140
4.32
140–245
12.43
245–450
27.29
450–600
31.07
700–1130
3.25
Eu(L)
3
⋅2H
2
O
peak/°C
88 (endo)
241 (exo)
311 (exo)
488 (exo)
θ°C
loss/%
30–140
4.35
140–455
43.53
455–600
26.12
800–1070
3.81
Gd(L)
3
⋅2H
2
O
peak/°C
90 (endo)
260 (exo)
503 (exo)
θ°C
loss/%
30–140
4.26
140–460
42.90
460–540
27.13
750–980
3.22
Tb(L)
Dy(L)
Ho(L)
3
⋅2H
2
O
peak/°C
90 (endo)
260 (exo)
505 (exo)
θ°C
loss/%
30–140
2.41
140–255
12.91
255–455
29.67
455–550
28.30
700–1000
3.57
3
⋅H
2
O
peak/°C
90 (endo)
255 (exo)
340 (exo)
500 (exo)
θ°C
loss/%
30–140
6.25
140–470
45.63
470–530
23.90
650–830
2.17
3
⋅3H
2
O
peak/°C
95 (endo)
290 (exo)
505 (exo)
θ°C
loss/%
30–140
6.22
140–455
44.77
455–520
24.13
600–780
2.41
Er(L)
3
⋅3H
2
O
peak/°C
90 (endo)
280 (exo)
495 (exo)
θ°C
loss/%
30–140
6.59
140–485
45.07
485–565
23.07
600–780
2.68
Tm(L)
3
⋅3H
2
O
peak/°C
90 (endo)
290 (exo)
520 (exo)
θ°C
loss/%
30–140
6.25
140–480
43.58
480–580
25.29
580–750
2.15
Yb(L)
3
⋅3H
2
O
peak/°C
90 (endo)
290 (exo)
520 (exo)
θ°C
loss/%
30–14
6.20
140–155
43.25
455–530
24.91
530–720
2.47
Lu(L)
3
⋅3H
2
O
peak/°C
90 (endo)
290 (exo)
505 (exo)
θ°C
loss/%
30–140
4.56
140–440
44.43
440–550
31.44
550–920
4.10
Y(L)
3
⋅2H
2
O
peak/°C
90 (endo)
265 (exo)
495 (exo)
720 (exo)
–1
–
1
589 cm suggesting a νanti-sym.(COO ) assignment,
lutetium compounds are shown in Figs 2c, d and e. The
same behaviour was also observed in the TG-DTA
profiles of 2-Cl-BP compounds with lighter trivalent
lanthanides [18].
while the theoretical results show the corresponding
–1
peak at 1380 cm with discrepancies –13.15%. (c) The
third assignment shows a medium contribution at
–
–1
1
429 cm suggesting a νsym.(COO ) assignment, while
These curves also show that the first mass loss for
all the compounds occurs within the same temperature
range (i.e. 30–140°C); the second mass loss also be-
gins at the same temperature (140°C), showing that the
thermal behaviour up to this step is not dependent on
the nature of the lanthanide ion. However, the features
shown by the next steps of thermal decomposition as
well as the mass lost in each step are characteristic of
each compound and no depend on the lanthanide ion
present, as already observed for the same lanthanide
and yttrium compounds with DMBP [12].
the theoretical results show the corresponding peak at
–1
1309 cm with discrepancies –8.40%.
The simultaneous TG-DTA and TG/DTG curves
of the compounds are shown in Fig. 2. This curves ex-
hibit mass losses in four or five consecutive and/or
overlapping steps and thermal events corresponding to
these losses. Two patterns of thermal behaviour are ob-
served up to 400°C. Firstly, a close similarity is noted
concerning the TG-DTA profiles of europium and dys-
prosium compounds, Figs 2a and b. On the other hand
gadolinium, terbium, holmium to lutetium and yttrium
compounds display another set of very similar
TG-DTA profiles. Due to the similarity between the
patterns of the thermal behaviour, only the TG-DTA
and TG/DTG curves of gadolinium, holmium and
For all the compounds, the first mass loss be-
tween 30–140°C, corresponding to endothermic
peaks at 88–95°C, is attributed to the dehydration,
which occurs in a single step and through a slow
process. This behaviour was also observed during the
J. Therm. Anal. Cal., 83, 2006
237

BANNACH et al.
dehydration of lanthanides and yttrium compounds
compounds (Gd, Tb, Ho–Lu, Y) the mass losses occur
in two steps. The similarity among these curves also
suggests that the decomposition mechanism should be
the same for these compounds.
with other phenyl-substituted derivatives of BP, and it
seems to be characteristic of compounds obtained in
amorphous state [11–15].
Once dehydrated, above 140 up to 580°C (Eu,
Yb); 550°C (Gd, Tb, Dy, Tm); 530°C (Ho, Lu, Y) and
For all the compounds, the final residue up to this
step was dissolved in nitric acid solution and did not in-
dicate the formation of intermediate, oxy- or dioxy-
carbonate as observed in the thermal decomposition of
lanthanides and yttrium compounds with 4-MeO-BP
and DMBP [11, 12]. The non formation of these inter-
mediates undoubtedly is due to the influence of the
chloro- as phenyl substituted of BP, as already observed
in the thermal decomposition of heavy trivalent
520°C (Er), the mass losses corresponding to exother-
mic events are attributed to oxidation of organic mat-
ter. For the europium and dysprosium compounds, the
mass losses occur in three steps without a plateau be-
tween the steps. The similarity of TG-DTA curves up
to this point suggests that the decomposition mecha-
nism is the same for both compounds. For the other
Fig. 3 DSC curves of the compounds: a – Eu(2-Cl-BP)
3
⋅2H
2
O (m=5.2 mg), b – Dy(2-Cl-BP)
i
3
2
⋅H O (4.7 mg),
c – Gd(2-Cl-BP) O (4.9 mg), d – Ho(2-Cl-BP)
3
⋅2H
2
3
⋅3H
2
O (5.3 mg) and e – Lu(2-Cl-BP)
3
⋅3H O (5.2 mg)
2
238
J. Therm. Anal. Cal., 83, 2006

2-CHLOROBENZYLIDENEPYRUVATE OF HEAVIER TRIVALENT LANTHANIDES AND YTTRIUM(III)
lanthanides and yttrium compounds with 4-Cl-BP [14]. Acknowledgements
Tests with AgNO solution on these residues dissolved
3
The authors thank FAPESP (Proc. 97/12646-8), CAPES and
in nitric acid solution indicated the presence of chloride
ions, and the X-ray powder patterns showed that the res-
idue up to this temperature is a mixture of the respective
metal oxide and oxychloride in no simple stoichiometric
relation, and in agreement with [14, 18].
CNPq Foundations (Brazil) for financial support. Computa-
tional facilities of IQ-UNESP and CENAPAD-UNICAMP.
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8
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Synlett, (2001) 147 and references therein.
8 C. B. Melios, V. R. Torres, M. H. A. Mota, J. O. Tognolli
and M. Molina, Analyst, 109 (1984) 385.
The DSC curves of europium, dysprosium, gado-
linium, holmium and lutetium compounds, as represen-
tative of the studied compounds are shown in Fig. 3.
As already observed in the TG-DTA curves, a
great similarity is also observed in the DSC curves of
europium and dysprosium compounds, as well as in
the gadolinium, terbium, holmium to lutetium and
yttrium compounds.
9
C. B. Melios, J. T. S. Campos, M. A. C Mazzeu,
L. L. Campos, M. Molina and J. O. Tognolli,
Inorg. Chim. Acta, 139 (1987) 163.
1
0 R. N. Marques, C. B. Melios, N. C. S. Pereira,
O. S. Siqueira, M. de Moraes, M. Molina and M. Ionashiro,
J. Alloys Compd., 249 (1997) 102.
These curves show endothermic and exothermic
peaks that all are in agreement with the mass losses
observed in the TG curves. The endothermic peak at
1
1 L. C. S. Oliveira, C. B. Melios, C. A. Ribeiro, M. S. Crespi
and M. Ionashiro, Thermochim. Acta, 219 (1993) 215.
8
8–95°C is assigned to the dehydration, which occurs
in single step.
The dehydration enthalpies found for these
compounds (Eu, to Lu and Y) were: 65.77, 55.63,
6.89, 121.65, 99.80, 109.59, 131.02, 119.78, 205.46
12 M. H. Miyano, C. B. Melios, C. A. Ribeiro, H. Redigolo
and M. Ionashiro, Thermochim. Acta, 221 (1993) 53.
1
1
1
1
3 N. S. Fernandes, M. A. S. Carvalho Filho, C. B. Melios
and M. Ionashiro, J. Therm. Anal. Cal., 59 (2000) 663.
4 N. S. Fernandes, M. A. S. Carvalho Filho, C. B. Melios
and M. Ionashiro, J. Therm. Anal. Cal., 73 (2003) 307.
5 R. N. Marques, C. B. Melios and M. Ionashiro,
Thermochim. Acta, 395 (2003) 145.
8
–
1
and 83.11 kJ mol , respectively.
6 N. S. Fernandes, M. A. S. Carvalho Filho, R. A. Mendes,
C. B. Melios and M. Ionashiro, J. Therm. Anal. Cal.,
Conclusions
7
6 (2004) 193.
17 G. Bannach, E. Schnitzler, C. B. Melios and M. Ionashiro,
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8 G. Bannach, R. A. Mendes, E. Y. Ionashiro, A. E. Mauro,
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9 (2005) 329.
From TG curves, elemental analysis and complexo-
metry results, a general formula could be established
for these compounds in the solid-state.
1
The experimental and theoretical infrared spec-
troscopic data suggest that 2-Cl-BP acts as a bidentate
ligand towards trivalent lanthanides and yttrium(III).
The TG-DTA, TG/DTG and DSC curves pro-
vided previously unreported information concerning
the thermal behaviour and thermal decomposition of
these compounds.
7
1
9 E. Y. Ionashiro, F. L. Fertonani, C. B. Melios and
M. Ionashiro, J. Therm. Anal. Cal., 79 (2005) 299.
0 M. Ionashiro, C. A. F. Graner and I. Zuanon Netto,
Ecl. Quim., 8 (1983) 29.
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Received: February 20, 2005
In revised form: May 26, 2005
DOI: 10.1007/s70973-005-6972-y
240
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