Synthesis, structural study, thermal, optical properties and characterization of the new compound [C6H7N2O2]3TeCl5·2Cl

Article abstract of DOI:10.1016/j.cclet.2017.04.005

The new organic-inorganic compound, [C₆H₇N₂O₂]₃TeCl₅·2Cl was synthesized and its structure was determined at room temperature in the triclinic system (P^?1) with the following parameters: a?=?10.5330(11)??, b?=?10.6663(11)??, c?=?15.9751(16)?, α?=?82.090(2)°, β?=?71.193(2)°, γ?=?68.284(2)° and Z?=?2. The final cycle of refinement led to R?=?0.057 and Rw?=?0.149. The crystal structure was stabilized by an extensive network of N–H?Cl and non-classical C–H?Cl hydrogen bonds between the cation and the anionic group. Several thermal analysis techniques such as thermogravimetric analysis, differential scanning calorimetric analysis and evolved gas analysis were used. We used isoconversional kinetics methods to determine the kinetics parameters. We observe that the decomposition of [C₆H₇N₂O₂]₃TeCl₅·2Cl entails the formation hydrochloric acid of nitroaniline as volatiles. The infrared spectra were recorded in the 4000–400?cm^?1 frequency region. The Raman spectra were recorded in the external region of the anionic sublattice vibration 50–1500?cm^?1. The optical band gap was calculated from the UV-Vis absorbance spectra using classical Tauc relation which was found to be 3.12 and 3.67?eV.

Full text of DOI:10.1016/j.cclet.2017.04.005

G Model
CCLET 4041 No. of Pages 7
Chinese Chemical Letters xxx (2017) xxx–xxx
Contents lists available at ScienceDirect
Chinese Chemical Letters
journal homepage: www.elsevier.com/locate/cclet
Original article
Synthesis, structural study, thermal, optical properties and
characterization of the new compound [C6H7N2O2]3TeCl5 2Cl
ꢀ
a
b
b
Dhaou Maraiia, , Jordi Farjas , Xavier Fontrodona , Mohamed Dammak
*
a
Laboratoire de Chimie Inorganique, Faculté des Sciences de Sfax, University of Sfax, BP 1171, 3000 Sfax, Tunisia
University of Girona, Campus Montilivi, Edif. PII, E17071 Girona, Catalonia, Spain
b
A R T I C L E I N F O
A B S T R A C T
Article history:
The new organic-inorganic compound, [C6H7N2O2]3TeCl5 2Cl was synthesized and its structure was
ꢀ
Available online xxx
determined at room temperature in the triclinic system ðPꢁ1Þ with the following parameters: a = 10.5330
(11) Å, b = 10.6663(11) Å, c = 15.9751(16)Å,
a b g
= 82.090(2)ꢂ, = 71.193(2)ꢂ, = 68.284(2)ꢂ and Z = 2. The final
Keywords:
cycle of refinement led to R = 0.057 and Rw = 0.149. The crystal structure was stabilized by an extensive
network of NꢁꢁHꢀ ꢀ ꢀCl and non-classical CꢁꢁHꢀ ꢀ ꢀCl hydrogen bonds between the cation and the anionic
group. Several thermal analysis techniques such as thermogravimetric analysis, differential scanning
calorimetric analysis and evolved gas analysis were used. We used isoconversional kinetics methods to
Thermal analysis
Kinetics parameters
Structural analysis
FTIR
Raman
Optical absorption
determine the kinetics parameters. We observe that the decomposition of [C6H7N2O2]3TeCl5 2Cl entails
ꢀ
the formation hydrochloric acid of nitroaniline as volatiles. The infrared spectra were recorded in the
4000–400 cmꢁ1 frequency region. The Raman spectra were recorded in the external region of the anionic
sublattice vibration 50–1500 cmꢁ1. The optical band gap was calculated from the UV-Vis absorbance
spectra using classical Tauc relation which was found to be 3.12 and 3.67 eV.
© 2017 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences.
Published by Elsevier B.V. All rights reserved.
1. Introduction
3-Nitroaniline contains three nitrogen atoms and three amino
substituents and crystallizes as a hydrogen-bonded solid that
The revolutionary increase in the number of synthesized and
structurally characterized coordination polymers in the last few
decades reflects the effort devoted to the search for catalytic,
conducting, luminescent, magnetic or porous materials [1,2].
Besides, the use of tellurium as a potential node of the metal-
organic framework allows a better understanding of the correla-
tions between structural features and physical characteristic [3]. In
addition, Te atoms act as a part of the heterometallic inorganic
clusters [4,5]. There are several types of interactions, such as the
interaction with another metal [6,7] or with halogens [8,9].
Therefore, tellurium-coordination polymers are organic-inorganic
hybrid materials with several potential applications [10].
comprises molecular tapes formed by C-H . . . N hydrogen bonds
between the adjacent molecules. As
a result, 3-nitroaniline
represents an extremely interesting ligand system for supramo-
lecular chemistry [12,13]. Generally, the solid state complexation of
m-nitroaniline with different organic and inorganic acids com-
prises mostly the weak hydrogen bonds of NꢁꢁHꢀ ꢀ ꢀCl and CꢁꢁHꢀ ꢀ ꢀCl
types [14–16]. So, the use of 3-nitroaniline with hexahydrotellurate
gives birth to a new [(C6H7N2O2)3 TeCl5
we report the synthesis of [C6H7N2O2]3TeCl5
These crystals are characterized by XRD, FTIR and Raman studies.
Their stability is characterized by means of thermal analysis.
ꢀ
2Cl] complex. In this paper
ꢀ2Cl single crystals.
Besides, there is a growing interest in m-Nitroaniline as nitro-
substituted derivatives of aromatic amines because aromatic
amines are highly toxic and they are suspected of having
carcinogenic properties [11]. For instance, 3-nitroaniline is
extensively used to treat wastewater.
2. Results and discussion
2.1. Structure description
Single crystal X-ray analysis shows that [C6H7N2O2]3TeCl5 2Cl
ꢀ
compound crystallizes, at room temperature, in the space group
ðPꢁ1Þ with two formula units in the unit cell (Z = 2). The cell
dimensions are: a = 10.5330(11) Å, b = 10.6663(11) Å, c = 15.9751
(16) Å,
a b g
= 82.090(2)ꢂ, = 71.193(2)ꢂ, = 68.284(2)ꢂ and V = 1578.0
* Corresponding author.
E-mail address: mariidhaou@hotmail.fr (D. Maraii).
http://dx.doi.org/10.1016/j.cclet.2017.04.005
1001-8417/© 2017 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences. Published by Elsevier B.V. All rights reserved.
Please cite this article in press as: D. Maraii, et al., Synthesis, structural study, thermal, optical properties and characterization of the new
compound [C6H7N2O2]3TeCl5 2Cl, Chin. Chem. Lett. (2017), http://dx.doi.org/10.1016/j.cclet.2017.04.005
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(3)Å3. The asymmetric unit of the title compound is depicted in
Fig.1 and shows the presence of an anionic entity formed by square
pyramid [TeCl5]ꢁ entities, two isolated Clꢁ and three independent
3-nirtoanilinium [C6H7N2O2]+.
Five chlorine atoms surround the tellurium atom in the anionic
species and form a square-based pyramidal coordination. Indeed,
the environment in the tellurium atom is characterized by five
TeꢁꢁCl bonds. The Te-Cl distances are between 2.327(2) Å and
2.642(2) Å. ClꢁꢁTeꢁꢁCl bond angles fall in the range of 89.55(9)ꢂ–
178.28(8)ꢂ. The selected bonds and angles are listed in Table S1 in
Supporting information. The projection of the atomic arrangement
of [C6H7N2O2]3TeCl5 2Cl compound in the (ac) plane is shown in
ꢀ
Fig. S1 in Supporting information. The structure is parallel
inorganic layers alternated by organic planes. Both planes are
parallel to the (a b) one. The C-N bond lengths vary from 1.456(9) Å
to 1.490(2) Å. CꢁꢁC bond lengths vary from 1.353(15) Å to 1.402
(17) Å and angles CꢁꢁCꢁꢁC, NꢁꢁCꢁꢁC, CꢁꢁNꢁꢁO are between 114.7
(1)ꢂ and 126.9(1)ꢂ. In the title compound, the entire ring is planar
and is built up by the atoms (C1, C2, C3, C4, C5, C6), (C7, C8, C9, C10,
C11, C12), (C13, C14, C15, C16, C17, C18).
Fig. 2. Dotted lines: the intermolecular hydrogen bonds contacts of the title
compound.
decomposition process. Three decomposition stages can be clearly
distinguished. The first of which is endothermic and appears as a
shoulder in the DTG signal. As for the second stage, it is located
around 200 ꢂC and involves the larger mass loss. This stage is an
exothermic process. Concerning the third stage, it is located
approximately between 250 ꢂC and 300 ꢂC and is also an
exothermic process. After the decomposition, the mass continues
to decrease steadily because the final decomposition product is not
stable. Indeed, the mass decreases up to 900 ꢂC where no solid
product is left.
In the [(C6H7N2O2)3TeCl5 2Cl], the organic species interact with
ꢀ
the inorganic group via NꢁꢁHꢀ ꢀ ꢀCl hydrogen bonds, as shown in
Table S2 and in Fig. 2. Actually, there are six strong (3.089(7) and
3.184(7) Å) and four weak (3.279(6) and 3.581(7) Å) NꢁꢁHꢀ ꢀ ꢀCl
hydrogen bonds [17]. The intermolecular hydrogen bonding
contacts CꢁꢁHꢀ ꢀ ꢀCl provide a linkage between the (C6H7N2O2)+
entities and the [TeCl5]ꢁ anions (3.585(8)–3.646(9) Å).
2.2. Thermal analysis
The evolution of the mass (TG signal) when the sample is
submitted to a constant temperature rise is shown in Fig. 3. The
sample is stable up to 130 ꢂC. The decomposition is triggered by an
endothermic process. This endothermic process is not a melting or
evaporation because it is thermally activated. The process shifts to
higher temperature when the heating rate is increased [18].
Besides, the analysis of the morphology of the solid sample at
150 ꢂC does not reveal any melting process.
In Fig. 3.b, we have plotted the evolution of the time derivative
of the TG signal (DTG) together with the DSC signal. Both
parameters are directly related to the transformation rate and
they allow an easier identification of the different stages of the
2.3. Kinetic analysis
In this section we perform a kinetic analysis to determine the
activation energy. Isoconversional methods allow the determina-
tion of the kinetic parameters without assuming any particular
reaction mechanism, i.e., they are model-free. They are based on
the determination of one or more of the system parameters
(temperature, transformation rate, and etc.) at which the same
degree of transformation,
a, has been reached for the measure-
ments performed at different constant temperatures (isothermal)
or different heating rates (non-isothermal). In general, non-
isothermal experiments are preferred [19] because they are easier
and faster to perform and can explore a wider temperature range.
Isoconversional methods rely on the hypothesis that at a given
a,
the transformation rate is only a function of temperature [19,20].
ꢀ
ꢁ
dlnðd
a
dTꢁ1
=dtÞ
E
a
R
¼ ꢁ
ð1Þ
a
Where the subscript
the gas constant and E
Eq. (1) results in a transformation governed by a single mechanism
a
indicates the degree of transformation, R is
a
is the activation energy. The integration of
where the rate constant, k (T) = A exp(ꢁE /RT), depends on
a
[21]:
a
a
a
ꢀ
ꢁ
da
E
a
¼ A exp ꢁ
fðaÞ
ð2Þ
a
dt
RT
A variation of E with
a is usually related to the occurrence of
a
complex transformations where several mechanisms are involved
(such as heterogeneous transformations, multi-step reactions, or
transformations depending on parameters other than
a and T)
[22–25]. In this context, Eq. (1) is an approximate relationship and
E
must be interpreted in terms of apparent activation energy.
In Fig. 4, we have plotted the evolution of the transformation
a
which was obtained directly from the TG analysis (Fig. 3). To
calculate the degree of the transformation, we have assumed that
Fig. 1. The asymmetric unit of [C6H7N2O2]3TeCl5 2Cl showing the atom-labeling
scheme.
ꢀ
a
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compound [C6H7N2O2]3TeCl5 2Cl, Chin. Chem. Lett. (2017), http://dx.doi.org/10.1016/j.cclet.2017.04.005
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3
depends linearly on the mass evolution:
the TG signal. On the other hand, the process is more evident in the
DSC signal, thus Kissinger analysis of the first DSC peak is able to
disclose the value of this initial barrier.
The Kissinger analysis of the second peak that is related to the
second stage delivers activation energy of 109 kJ/mol. This second
stage covers most of the decomposition process. Friedman analysis
reveals a roughly constant activation energy of around 125 kJ/mol
min ꢁ mðtÞ
aðtÞ ¼
ð3Þ
min ꢁ mfin
Where min and mfin are the initial and final masses, respectively.
To determine the activation energy, we have used the Friedman
method. The result is plotted in Fig. 5. From Fig. 5, it is apparent
that the activation energy is not constant, this complex behavior is
related to the overlapping of different processes. From Fig. 4, it is
clear that at least three different mechanisms are involved in the
decomposition process. Since from Fig. 4 three DSC peaks can be
clearly distinguished, we also perform the Kissinger analysis which
is based on the determination of the peak temperature TM. The
peak temperature is the temperature at which the transformation
rate is at its maximum. If we assume that, within the range where a
for 0.25 <
experimental uncertainties in the determination of
fact that E shows an evolution that points out that the kinetics of
a
< 0.7. This discrepancy could be partly attributed to the
a
and to the
a
this second stage could not be reduced to a single mechanism
description. From Figs. 3b and 4, it can be noted that the DTG, DSC
and da/dt curves show a structure that is characteristic of the
occurrence of a complex behavior.
Finally, the Kissinger plot deviates significantly from linearity in
the third process. As can be seen from Fig. 3, the DSC peaks
obtained at 10 and 20 K/min nearly overlap and are far away from
the peak obtained at 5 K/min. This behavior is in contradiction with
the expected separation between the peaks for thermally activated
process. The use of the Arrhenius equation to describe the reaction
kinetics is based on the assumption that the reaction takes place in
a parameter region far from equilibrium. The deviations from the
Arrhenius behavior are to be expected when reactions take place
near equilibrium. In these cases, the transformation rate is also
governed by the temperature difference with respect to the
peak is observed, the transformation is ruled by
mechanism, the transformation rate is described by single process
equation [26,27].
a single
d
dt
a
¼ AexpðꢁE=RTÞ
ð4Þ
Contrarily to Eq. (2), E and A are assumed constant, they do not
depend on . From Eq. (4), it can easily derive the Kissinger
a
equation [27] that relates the peak temperature, TM, with the
kinetic parameters:
!
ꢂ
ꢃ
b
TM2
E
RTM
AR
f0ðaM
E
ln
¼ ꢁ
þ ln
ꢁ
Þ
ð5Þ
Where
b
is the heating rate,f0ðaMÞ ꢃ df=da a
j
and aM is the
aM
¼
degree of transformation at TM.
Eq. (5) has been used to determine the activation energy for a
large variety of transformations [28–35]. Kissinger method relies
on the determination of the peak temperature TM,i from experi-
ments carried out at different heating rates bi. The activation
ꢄ
ꢅ
energy is obtained from a linear fit of the plot ln
b
i=T2M;i versus 1/
TM,i. The results are plotted in Fig. 6 for the three DSC peaks
observed in Fig. 3.
The Kissinger analysis reveals that the endothermic process
that triggers the decomposition exhibits a quite high energy
barrier, 168 kJ/mol. Conversely, the Friedman analysis delivers
significantly smaller activation energy. The reason is that the first
process involves a very low mass loss as it is apparent from Fig. 3.
For instance, the DTG curve shows only a small shoulder. Therefore,
this process is not caught by the Friedman analysis that is based on
Fig. 4. Evolution of the transformed fraction and the transformation rate for the
thermal decomposition of [C6H7N2O2]3TeCl5
heating rates.
ꢀ
2Cl measured by TG (Fig. 3) at several
Fig. 3. Simultaneous TG-DSC evolution of [C6H7N2O2]3TeCl5 2Cl when the sample is submitted to a continuous heating ramp at different heating rates under N2 atmosphere:
ꢀ
(a) TG-DSC signal, (b) DTG-DSC signal. The sample mass and the DSC signals are normalized to the initial sample mass.
Please cite this article in press as: D. Maraii, et al., Synthesis, structural study, thermal, optical properties and characterization of the new
compound [C6H7N2O2]3TeCl5 2Cl, Chin. Chem. Lett. (2017), http://dx.doi.org/10.1016/j.cclet.2017.04.005
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equilibrium temperature. Indeed, when the temperature
approaches that of equilibrium, the processes obtained at different
heating rates tend to overlap. Therefore, the non-linearity of
Kissinger plot may be interpreted in terms of a reaction kinetics
controlled by the separation from equilibrium. In the Friedman
plot, we observe anomalous and very low activation energy. The
latter also indicates that the assumption that the reaction rate is
governed by Arrhenius dependence does not hold.
2.4. EGA analysis
The main volatiles identified by EGA when [C6H7N2O2]3-
TeCl5 2Cl is heated at a rate of 5 K/min are shown in Fig. 7. In
ꢀ
Fig. 7 only the evolution of the main fragments is exhibited, but
volatile identification is based on the complete analysis of the
defragmentation pattern. The first and main volatile is hydro-
chloric acid, so the decomposition of [C6H7N2O2]3TeCl5 2Cl is
ꢀ
Fig. 6. Kissinger plot of the three DSC peaks shown in Fig. 3.
probably triggered by the release of the two chloride atoms. Next,
we observe the formation of nitroaniline C6H4(NH2)(NO2).
Therefore, the released chlorine atoms may react with
[C6H7N2O2]3TeCl5 to form C6H4(NH2)(NO2), TeCl5 and 2HCl. The
stoichiometry of the process is:
stretching vibrations of (NO2) are observed at 1344 and 1528 cmꢁ1
The (CꢁꢁCꢁꢁH) bending mode is located at 1087 cmꢁ1. The
vibrations modes between 891 and 806 cmꢁ1 are due to the
(CꢁꢁN) asymmetric and symmetric stretching vibrations. The
.
[C6H7N2O2]3TeCl5
2 H2
ꢀ
2Cl ! TeCl5 + 3
[C6H4(NH2)(NO2)] + 2HCl + 1/
(6)
deformation of (CꢁꢁC) bond is observed at 720 cmꢁ1
.
The Raman spectrum is illustrated in Fig. S2 and Table S1. In
comparison with previous research works reported on similar
compounds containing [TeCl5] [39,40], the asymmetric stretching
The final solid residue is TeCl5 which is known to be a volatile,
because the components of the form MXn with n = 1, 2, . . . ; M = Te,
P, Cu, . . . and X = Cl, Br, I, F, . . . have boiling points around 150 ꢂC
to 300 ꢂC for example the boiling point of SeBr6 is 180 ꢂC [36]. So
the final steady mass evolution after decomposition up to a null
residue (zero final mass) is probably due to the evaporation of
TeCl5.
The formation of small amounts of H2O is probably related to
the reaction of HCl with residual O2. As for the formation of CO2 at
higher temperature, it is probably related to the decomposition of
nitroaniline in the gas phase.
of (NO2) and the deformation of (CꢁꢁH) are observed at 1355 and
1214 cmꢁ1, respectively. Besides, the band located at 806 cm
is
ꢁ1
caused by the symmetric stretching of the (CꢁꢁN). The observed
bands at 673 cmꢁ1 are associated with the (NO2) rocking mode.
The bands corresponding to the (TeꢁꢁCl) stretching in-plane
mode appear at 340 cmꢁ1. The stretching modes of (TeꢁꢁCl) occur
between 265 cmꢁ1 and 311 cmꢁ1 and the deformation out-of-plane
of (TeCl5) modes can be observed between 65 cmꢁ1 and 108 cmꢁ1
.
2.6. Optical study
2.5. Infrared and Raman spectroscopy
The optical properties of solids provide an important tool for
studying energy band structure. The optical absorption spectrum
shown in Fig. S3 in Supporting information indicates that there is a
strong absorption at 338 nm and 397 nm. This may be due to
nitrogen-containing aromatic systems or electronic excitation in
this region [41,42]. Essentially, a high energy raises the electrons to
higher bands, so the crystal structure absorbs the light, while the
light without enough energy to raise the electrons to the following
band will pass through the structure. The optical energy band gap
The IR spectrum of this compound (Fig. S5 and Table S1 in
Supporting information), shows the characteristic absorption
peaks of the [C6H7N2O2]+ cation [37,38]. The peaks at 3426 cmꢁ1
correspond to the (NꢁꢁH) stretching vibrations. The symmetric
stretching vibrations of (CꢁꢁH) are observed at 3071 cmꢁ1. The
bands observed between 2850 and 2569 cmꢁ1 are assigned to the
asymmetric stretching vibrations of the (CꢁꢁH) bond. The (NꢁꢁH)
bending is observed at 1614 cmꢁ1. The symmetric and asymmetric
for the [C6H7N2O2]3TeCl5
Tauc relation [43,44] as given below:
ꢀ
2Cl crystal was calculated by classical
a
hy
= A(h ꢁ Eg)n
y
(7)
Where A is a constant, h
y
is the photon energy, Eg is the energy
band gap,
a is the absorption coefficient given by a= 2.303(Ab/t),
where Ab is the absorbance and t is the thickness of cuvette which
is 0.5 cm in the present case. The value of n = 1/2, 3/2, 2 or 3
depending on the nature of the electronic transition responsible
for absorption. The value of n = 1/2 allows for the direct transition,
thereby giving direct band gap. The direct optical band gap of the
crystal has also been determined by plotting (
photon energy (h ).
Fig. S4 in Supporting information shows the plot of (
photon energy (h ) for the [C6H7N2O2]3TeCl5
optical energy gap Eg is determined from the intersection of the
extrapolated line with the photon energy axis at ( = 0). The direct
optical band gap of the crystal is found to be 3.12 and 3.67 eV. As a
a
h
y
)2 against the
y
2
ah
y)
vs.
y
ꢀ2Cl crystal. The
a
Fig. 5. Friedman analysis of the evolutions shown in Fig. 4.
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compound [C6H7N2O2]3TeCl5 2Cl, Chin. Chem. Lett. (2017), http://dx.doi.org/10.1016/j.cclet.2017.04.005
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5
4. Experimental
4.1. Synthesis of (C6H7N2O2)3TeCl5.2Cl compound
[C6H7N2O2]3TeCl5 2Cl is obtained from a mixture of C6H6N2O2
ꢀ
(99.98%), and TeCl4 (98%), which was dissolved in 38% concentrat-
ed HCl acid and stirred for a few minutes at room temperature.
After slow evaporation, neddles-shaped monocrystals appeared in
the solution. The colorless crystals were collected by filtration and
washed rapidly with cold ethanol. The stoichiometry of the process
is:
3(C6H6N2O2) + TeCl4 + 3HCl ! [C6H7N2O2]3TeCl5
ꢀ
2Cl
4.2. Characterization
4.2.1. X-ray diffraction
The crystal data, collected reflections and parameters of the
final refinement are reported in Table 1. Intensity data was
collected using a Bruker APEXII CCD four circle diffractometer with
Fig. 7. EGA analysis of [C6H7N2O2]3TeCl5 2Cl when is submitted to a constant
ꢀ
temperature rise of 5 K/min in vacuum (10ꢁ5 mbar).
consequence of this wide band gap, the grown crystal has a large
transmittance in the visible region. The large transmission in the
entire visible region enables it to be a good candidate for electro-
optic applications [45].
graphite monochromated (Mo K
the heavy atoms were obtained from
a
). The positional parameters for
a
three-dimensional
Patterson map, while the non-H atoms were found from successive
difference Fourier Maps. The structure is refined by full matrix
least squares using anisotropic temperature factors for all non-
hydrogen atoms. The H atoms were all located in a difference map,
but those attached to carbon atoms were repositioned geometri-
cally. The H atoms were initially refined with soft restraints on the
bond lengths and angles to regularize their geometry and Uiso (H)
(in the range 1.2–1.5 times Ueq of the parent atom), after which the
positions were refined with riding constraints. Calculations were
performed with the SHELXS [46] and SHELXL [47] programs, using
the scattering factors enclosed therein. The structural graph was
created with ORTEP [48] and DIAMOND programs [49].
3. Conclusion
[C6H7N2O2]3TeCl5 2Cl single-crystals have been grown by the
ꢀ
slow evaporation method. The obtained material crystallizes in the
space group ðPꢁ1Þ with triclinic system. The crystal structure is
stabilized by the various types of NꢁꢁHꢀ ꢀ ꢀCl and CꢁꢁHꢀ ꢀ ꢀCl
hydrogen bonds.
The TGA and DSC study shows that the compound is stable up to
130 ꢂC; thermal analysis reveals the existence of three decomposi-
tion stages at 130, 200 and between 250 ꢂC and 300 ꢂC. The kinetic
analysis reveals that the decomposition is a complex transforma-
tion that involves several processes and that the decomposition is
triggered by and endothermic process whose barrier the activation
energy is 168 kJ/mol. From Evolved gas analysis we observed that
the decomposition is triggered by the release of two chloride
atoms and that the decomposition entails the formation of
hydrochloric acid of and nitroaniline as volatiles. The presence
of all fundamental functional groups of the grown sample was
confirmed by Raman scattering and infrared spectroscopy. From
UV-visible spectrum, the cut-off wavelength and optical band gap
were (397 nm) 3.12 eV and (338 nm) 3.67 eV.
4.2.2. Spectroscopic measurement
Fourier transform infrared (FT-IR) measurements were per-
formed at room temperature on a Perkin-Elmer FT-IR Paragon 1000
PC spectrometer over the 4000–400 cm-1 region. Samples were
prepared in KBr pellets. As for the Raman scattering spectrum, it
was recorded using
a T-64000 Raman spectrometer (ISA,
JobinYvon) with standard attachments. The beam sources were
argon krypton titan-sapphire and semi-conductor lasers. The
spectrum was recorded in the range of 50 cmꢁ1 to 1500 cmꢁ1. The
UV–vis spectral analysis was carried out between 200 nm and
Table 1
Experimental data for X-ray diffraction study of [C6H7N2O2]3TeCl5
ꢀ
2Cl.
Crystal data
Data collection
Chemical formula
Molecular weight (g\mol)
T (K)
Crystal size (mm)
Crystal system
Space group
a (Å)
[C6H7N2O2]3TeCl5
793.16
293 (2)
0,44x 0,32x 0,25
Triclinic
ðPꢁ1Þ
ꢀ
2Cl
Diffractometer
Wavelength Mo
Theta Range (ꢂ)
Indexes range
Brucker Kappa Appex (II)
0.71073 Å
1.35–25.00
h = ꢁ12 !7
k = ꢁ12 !12
l = ꢁ18 ! 15
8175
5487
4506
0.017
4506\0\343
0.057
10.5330 (11)
10.6663 (11)
15.9751 (16)
82.090 (2)
71.193 (2)
68.284 (2)
1578.0(3)
2
Measured reflections
Independent reflections
Observed refl (I > 2
R int
Data\restraints\parameters
R
b (Å)
c (Å)
s
(I))
a
b
d
(ꢂ)
(ꢂ)
(ꢂ)
v (Å3)
Z
WR2
Goof = S
0.149
1.07
0.570\ꢁ0.530
D calc (gcmꢁ3
)
1.669
1.577
Drmax
\
Drmin (eÅꢁ3
)
Absorption coefficient (mmꢁ1
)
F (000)
780
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G Model
CCLET 4041 No. of Pages 7
6
D. Maraii et al. / Chinese Chemical Letters xxx (2017) xxx–xxx
800 nm using UV–vis absorption spectrophotometer (T90 + UV/
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Differential scanning calorimetric (DSC) analysis was per-
formed using a DSC 822 METTLER TOLEDO instrument for
temperatures ranging from 300 K to 750 K. The samples were
heated at a constant rate of 10 K/min. A polycrystalline sample of
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sample mass measured at room temperature after the experiment.
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in a quartz tube at a pressure of about 10–5 mbar. Samples are
heated at a constant rate of 5 K/min using an external furnace.
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This work was partially funded by the Tunisian Ministry of
Higher Education and Scientific Research, the Spanish Programa
Nacional de Materiales through project MAT2014-51778-C2-2-R
and by the Universitat de Girona contract No. MPCUdG2016/059.D.
Maraii acknowledges the financial support of the Tunisian Ministry
of Higher Education and Scientific Research.
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Appendix A. Supplementary data
Supplementary data associated with this article can be found, in
the online version, at http://dx.doi.org/10.1016/j.cclet.2017.04.005.
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compound [C6H7N2O2]3TeCl5 2Cl, Chin. Chem. Lett. (2017), http://dx.doi.org/10.1016/j.cclet.2017.04.005
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Please cite this article in press as: D. Maraii, et al., Synthesis, structural study, thermal, optical properties and characterization of the new
compound [C6H7N2O2]3TeCl5 2Cl, Chin. Chem. Lett. (2017), http://dx.doi.org/10.1016/j.cclet.2017.04.005
ꢀ