Synthesis, characterization and thermal behavior of tetrakis(melamine2+) bis(melamine+) pentakis(monohydrogenphosphate) tetrahydrate

Article abstract of DOI:10.1016/j.molstruc.2016.05.073

A new organic-inorganic salt, tetrakis (2,4,6-Triamino-1,3,5-Triazin-1,3-diium) bis (2,4,6-Triamino-1,3,5-Triazin-1-ium) pentakis (monohydrogenphosphate) tetrahydrate, 4C₃H₈N₆⁺². 2C₃H₇N₆⁺. 5HPO₄^2-. 4H₂O was synthesized through the reaction of melamine and phosphoric acid in an acidic medium HCl/H₂O. It was then characterized by X-ray diffraction. The title compound crystallizes in monoclinic system with non-centrosymetric space group P 21 with lattice parameters a = 11.3008 ?, b = 20.9798 ?, c = 12.2679 ?, α = 90°, β = 117.236°, γ = 90°, Z = 2 and V = 2586.10 (?)³. The UV-vis absorption spectrum UV-vis showed that the crystal has a good optical transmittance in the entire visible region with a lower cut off wavelength of 290 nm. The vibrational frequencies of various functional groups present in the crystal were identified by FT-IR analysis. The chemical structure of the compound was also confirmed by ¹H, ¹³C and ³¹P NMR spectroscopy. TGA-DTA analysis revealed that the materials have a good thermal stability without any melting.

Full text of DOI:10.1016/j.molstruc.2016.05.073

Accepted Manuscript
2+
Synthesis, characterization and thermal behavior of tetrakis(melamine
)
+
bis(melamine ) pentakis(monohydrogenphosphate) tetrahydrate
Hakima Ait Youcef, Salah Chafaa, Rachida Doufnoune, Tahar Douadi
PII:
S0022-2860(16)30518-X
10.1016/j.molstruc.2016.05.073
MOLSTR 22587
DOI:
Reference:
To appear in: Journal of Molecular Structure
Received Date: 28 January 2016
Revised Date: 19 May 2016
Accepted Date: 20 May 2016
Please cite this article as: H.A. Youcef, S. Chafaa, R. Doufnoune, T. Douadi, Synthesis, characterization
2+
+
and thermal behavior of tetrakis(melamine ) bis(melamine ) pentakis(monohydrogenphosphate)
tetrahydrate, Journal of Molecular Structure (2016), doi: 10.1016/j.molstruc.2016.05.073.
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to
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ACCEPTED MANUSCRIPT
Synthesis, Characterization and Thermal Behavior of Tetrakis(Melamine2+)
Bis(Melamine+) Pentakis(monohydrogenphosphate) Tetrahydrate
Hakima Ait Youcef 1,*, Salah Chafaa 1, Rachida Doufnoune 2, Tahar Douadi 1
1Laboratoire d’Electrochimie des Matériaux Moléculaires et des Complexes (LEMMC).
Département de Génie des procédés, Faculté de Technologie, Université Ferhat Abbas
Sétif-1, 1900 Algérie.
2Unité de Recherche sur les Matériaux Emergeants -Sétif- URMES, Equipe de Valorisation
des Matériaux Polymériques, Université Ferhat Abbas Sétif-1, Algérie.
*Corresponding author. E-mail address: hakimaaityoucef@yahoo.fr (Hakima Ait Youcef)
Abstract
A new organic–inorganic salt, tetrakis (2,4,6-triamino-1,3,5-triazin-1,3-diium) bis (2,4,6-
+2
triamino-1,3,5-triazin-1-ium) pentakis (monohydrogenphosphate) tetrahydrate, 4C3H8N6 .
+
2-
2C3H7N6 . 5HPO4 . 4H2O was synthesized through the reaction of melamine and phosphoric
acid in an acidic medium HCl/H2O. It was then characterized by X-ray diffraction. The title
compound crystallizes in monoclinic system with non-centrosymetric space group P 21 with
lattice parameters a=11.3008Å, b = 20.9798 Å, c=12.2679 Å, α=90°, β=117.236°, γ=90°,
Z = 2 and V = 2586.10 (Å)3. The UV-vis absorption spectrum UV-vis showed that the crystal
has a good optical transmittance in the entire visible region with a lower cut off wavelength of
290 nm. The vibrational frequencies of various functional groups present in the crystal were
identified by FT-IR analysis. The chemical structure of the compound was also confirmed by
1H, 13C and 31P NMR spectroscopy. TGA-DTA analysis revealed that the materials have a
good thermal stability without any melting.
Keywords: Melamine; phosphoric acid; X-ray crystallography; FT-IR; FT-NMR; Thermal
analysis (TGA & DTA).
1. Introduction
Melamine (2,4,6-triamino-1,3,5-triazine) and its derivatives are widely used as
industrial chemicals in the manufacture of dyes, plastics, fertilizers, textiles and its polymers
play an important role in technological applications. If used in polymeric like epoxy resins,
cellulose or flax fibers, melamine acts as a flame retardant [1-6]. The recent toxicological and

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pharmacological investigations explored nephrotoxicity, crystal formation in kidney and renal
toxicity induced by melamine or its derivatives [7,8].
Melamine is an organic base which is able to form stable salts with most organic and
inorganic acids. Many of these salts, such as those with boric acid, phosphoric acid,
polyphosphoric acid, cyanuric acid, and sulfuric acid, are either commercial or have the
potential to be viable as flame-retardant additives.
Several researchers have already studied the thermal behavior of melamine and its
salts [9-12]. The presence of triazine ring in their structure gives improved hydrolytic and
thermal stability [6]. Melamine and its salts are widely used in the formulation of fire
retardant additive systems for polymeric materials [13-15]. Melamine also readily forms
insoluble adducts with many organic and inorganic acids [16,17]. Thermal and flame
retardation properties of melamine phosphate-modified epoxy resins were studied by Chen et
al. [18]. As a continuation of these studies we synthesized a new complex of phosphonic acid
with melamine as a crystal.
Melamine phosphates are considered to be attractive alternatives to halogen-containing
flame-retardants because the latter release toxic and corrosive gases during combustion. The
advantages of the flame-retardant characteristics of melamine phosphates materials are mainly
attributed to an enhanced thermal stability [19,20], so an elucidation of their packing
characteristics is particularly important.
Melamine is an interesting molecule in the field of crystal engineering [21-23] and
supramolecular chemistry [24-30]. Crystals of melaminium salts exhibit interesting properties.
Some melamine salts exhibit nonlinear optical behavior [31-33] like second harmonic
generation (SHG). Melamine family crystals have over the years been subjected to extensive
investigation by several researchers for their nonlinear optical properties.
Crystals of melaminium selenate with non-centrosymmetric space group are optically
active and generate the SHG [32]. High efficiency of SHG is observed in the crystals of
double protonated melaminium bis(trichloroacetate) dihydrate [34]. Another non-
centrosymmetric crystal of melaminium phosphate may also be used as a material for non-
linear optics [35].
Many studies were performed to explain the behavior of melamine molecule in the
solid state [36-42]. Generally, the solid state complexation of melamine with different organic

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and inorganic (mineral) acids has an interesting aspect. Particularly the hydrogen bonded
system, which comprises most frequently the weak hydrogen bonds of N–H···O and
O–H···O types [43-47].
Compounds containing partially protonated melaminium cations (M+, M2+) combined
with different organic and inorganic counter ions have been reported. For the crystalline
melamine and its organic or inorganic salts, most crystals contain only one melamine moiety,
i.e. the neutral molecule, single or double protonated melaminium cations [25-33].
It is especially important to notice that X-ray experiments are not sufficiently sensitive
to the presence of hydrogen participating in such intermolecular interactions as the precise
localization of hydrogen bonds is difficult and even impossible sometimes (for very strong
hydrogen bonds).
In this work, we have synthesized a new melaminium salt, namely: tetrakis (2,4,6-
triamino-1,3,5-triazin-1,3-diium) bis (2,4,6-triamino-1,3,5-triazin-1-ium) pentakis (monohy-
+2
+
2-
drogenphosphate) tetrahydrate, 4C3H8N6 . 2C3H7N6 . 5HPO4 . 4H2O (which will be
referred to as 4M+22M+5P 4H2O) as a crystal, and its structure has been determined by X-ray
diffraction. To establish the chemical structure of 4M+22M+5P 4H2O, FT-IR spectroscopy and
NMR studies have also been carried out. The thermal decomposition behavior of the title
compound has been studied by means of thermogravimetric analysis.
2. Experimental
2.1 Synthesis
4M+22M+5P4H2O compound was synthesized by the chemical reaction of a
commercially available melamine with phosphoric acid (Aldrich, purity: 99% and 85%
respectively).These chemicals were used as supplied in a molar ratio of 1:6. To the hot
aqueous solution of melamine, phosphoric acid solution was added slowly and the mixture
was heated and kept at a minimum temperature of 80 °C under continuous stirring. Then a
10% solution of HCl was added drop-wise to the mixture reaction and stirred continuously to
get the homogenous solution. The progress of the reaction was monitored by TLC analysis.
After 4 hours, a white precipitate was formed. The mixture was filtered and then allowed to
cool, and the purity of the synthesized salt was further improved by a re-crystallization
process. Tiny white crystals of the title compound were obtained after a period of time

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ranging from two to three weeks. The reaction scheme and the photograph of the grown
crystal are shown in Fig. 1. and Fig. 2.
Fig. 1. Reaction scheme for the synthesis of Melaminium pentakis(monohydrogenphosphate)
tetrahydrate.
Fig. 2. Photograph of Melaminium pentakis(monohydrogenphosphate) tetrahydrate.
2.2 Characterization
The grown crystal of the title compound was subjected to single crystal XRD analysis
using a Bruker AXS BV CCD diffractometer equipped with the graphite monochromator and
using MoKα radiation (λ = 0.71073 Å) at 293 K. The structure was solved by the SHELXS-97
direct methods and refined by the full-matrix least square method using the SHELXL-97
program [48]. Anisotropic thermal factors were determined for all non-hydrogen atoms. Unit
cell refinement using all observed reflections and data reduction were performed using
SAINT. All crystallographic parameters were deposited in the CCDC. The UV–Visible
spectrum of melaminium pentakis(monohydrogenphosphate) tetrahydrate was recorded
between 200–800 nm using a Perkin Elmer Lambda 650 Spectrophotometer, the sample for
this measurement was finely grounded and mixed with KBr. The FT-IR spectrum was
recorded using Bruker FT-IR spectrometer in the region 4000–400 cm-1 at room temperature

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using the KBr pellet technique and each IR spectrum was acquired in 10 scans at 2 cm-1
1
13
31
resolution. H NMR, C NMR and P NMR spectra of the title crystal were recorded using
DMSO-d6 as solvent on a Bruker Avance III 400 MHz spectrometer at room temperature. The
thermal behavior of the crystal was determined by thermo gravimetric analysis and
differential thermal analysis using a Perkin Elmer TGA 4000 at a heating rate of 10°C/min in
a nitrogen atmosphere (50 ml/min) at the temperature range over 30–900 °C.
3. Results and discussion
3.1 Single crystal X-ray diffraction analysis
The single crystal XRD data of the title crystal indicates that it crystallizes in a
monoclinic system with non-centrosymetric space group P 21 and Z = 2. The crystal structure
parameters are a = 11.3008 Å, b = 20.9798 Å, c = 12.2679 Å,
α = 90°, β = 117.236°,
γ = 90°. In accordance with the crystallographic data, during the complex formation, the acidic
protons of phosphoric acid were transferred into the melamine molecules giving single
protonated melaminium cations, and double protonated melaminium cations. The unit cell
structure of melaminium penta monohydrogenephosphate tetrahydrate is shown in Fig. 3. The
asymmetric unit contains two formal molecules which consist of two single protonated
melaminium cations, four double protonated melaminium cations, five monohydrogen
phosphate anions and four molecules of water. The crystal data and structure refinement
details are given in Table 1. The detailed fractional atomic coordinates and equivalent isotopic
displacement parameters were deposited in CCDC with the number 981733.
Fig. 3.Packing of the molecules in elementary unit cell.

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It is to be noted that, compounds containing partially protonated melaminium cations
(M+ and M2+) combined with different organic and inorganic counter-ions are widely reported
[25-28,49-55]. In studies of the crystalline melamine and its organic or inorganic salts, most
crystals contain only one melamine form, i.e. the neutral molecule combined with single or
double protonated melaminium cations [30,56,57]. In this paper we describe the structure of
single protonated (M+) and double protonated (M2+) crystal.
3.2 Optical absorption analysis
Efficient nonlinear optical crystals have an optical transparency and lower cutoff
wavelength between 200 and 300 nm [58]. The absorption spectrum of 4M+22M+5P4H2O
crystal is shown in Fig. 4.
1,0
0,8
0,6
0,4
0,2
0,0
200
300
400
500
600
700
800
Wavelength (nm)
Fig. 4.UV–Vis spectrum of melaminium pentakis(monohydrogenphosphate) tetrahydrate.
The lower cut off wavelength of 4M+22M+5P4H2O crystal was found to be at 290 nm.
There is a strong absorption at 245 nm due to nitrogen-containing aromatic systems or an
electronic excitation in this region [59,60]. In general, the absorption peaks of benzene appear
mainly around 200 nm, also and require greater energy than that required for π-π* transition
and hence its absorption shows the blue end of the spectrum [60]. It is seen from the
absorption spectrum that the absorption is minimum between 260 and 800 nm and the lower
cut off wavelength is 290 nm which is sufficient for laser frequency doubling and other
related opto-electronic applications in the ultra violet and visible region.

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3.3 FT-IR analysis
The functional groups present in the synthesized compounds can be easily identified
using The Infrared spectroscopy. The recorded FT-IR spectrum of 4M+22M+5P4H2O crystal is
presented in Fig. 5.
1,2
1,0
0,8
0,6
0,4
0,2
0,0
3500 3000 2500 2000 1500 1000
Wave number (cm-1)
500
Fig. 5. FTIR spectrum of melaminium pentakis(monohydrogenphosphate) tetrahydrate.
The characteristic frequency of the functional groups present in the title crystal were
assigned and are presented in Table 2. The bands observed in the measured region arise from
internal vibrations of melaminium cations, monohydrogenphosphate anions and water
molecules. Melaminium residues often form hydrogen bonds of N–H···N and N–H···O types.
The NH2 groups interact with the acid residue through weak N–H···O hydrogen bonds. The
band observed at 3420 cm-1 in the infrared spectrum is due to the OH stretching of water
molecules [61]. The strong and broad band observed at 3379 cm–1 is ascribed to NH2
symmetric stretching vibrations, while the broad band at 3158 cm-1 is attributed to N–H···O
and N–H···N stretching. The two IR broad bands at 2837 cm–1and 2712 cm–1 are assigned to
NH2 asymmetric stretching [36] and P–OH stretching of the hydrogen bonded to the PO4
units[62]. The medium band at 2354 cm-1 is due to the vibrations of the hydrogen bond
formed by water molecules [63,64]. The sharp and broad infrared bands at 1739 cm-1 and
1664 cm-1 are assigned to NH2 bending [36]. The bands at 1510 cm-1 and 576 cm-1 are
attributed to the side chain asymmetric C–N stretching and in plane C–N bending vibration

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[36]. The medium strong band at 1405 cm–1 is due to the semi-circle stretching vibrations
mechanically coupled with exogenous C–N contract and NH bending vibration [40,41]. The
medium sharp bands at 1246 cm-1, 1108 cm-1 and 860 cm-1 are ascribed to the stretching
vibration of P=O, P–O and P–O(H) bonds respectively. These three frequencies indicated the
presence of an (HPO4)- 2 entity in the structure of the compound [65]. The band at 1050 cm–1
was assigned to triazine ring breathing [36,39], while the band at 991 cm–1 was attributed to
triazine ring N, in-plane radial type of vibration [40,41]. This band appeared for all melamine
complexes. The medium strong band at 784 cm-1 is due to ring-sextant out of plane bending
vibration [36].
3.4 FT-NMR analysis
The 1H NMR, 13C NMR and 31P NMR spectra are presented in Fig. 6, Fig. 7 and Fig. 8
respectively.
10,5
9,0
7,5
6,0
4,5
3,0
1,5
0,0
(δ) ppm
Fig. 6. 1H NMR spectrum of melaminium pentakis(monohydrogenphosphate) tetrahydrate.
1
In the H NMR spectrum of melamine in DMSO-d6, all the NH2 groups give a single
signal at 6.20 ppm. This peak was shifted to 7.409 ppm in the present case and this could be
due to the addition of phosphoric acid [66]. A broad signal appears at 8.985 ppm and can be
attributed to NH proton of the ring. The broadening of the signal may be due to the
involvement of protons in hydrogen bonding with the monohydrogenphosphate oxygen P=O.
The peak at 2.5 ppm is due to residual protons of deuterated DMSO-d6. The chemical shift of
the proton in –OH and NH2 groups depends upon the temperature, solvent, concentration and
the neighboring groups. The (phosphoric) –OH proton gives a singlet at 5.752 ppm.

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225 200 175 150 125 100 75 50 25
0
-25
(δ) ppm
Fig. 7. 13C NMR spectrum of melaminium pentakis(monohydrogenphosphate) tetrahydrate.
The 13C NMR spectrum shows that, the signals at 146.655 and 157.452 ppm are due to
carbon atoms of melamine+ and melamine2+ molecules with the same environment
respectively. A septet of signals observed around 40 ppm is due to the DMSO-d6 solvent.
30
20
10
0
-10
-20
-30
(
δ
) ppm
Fig. 8. 31P NMR spectrum of melaminium pentakis(monohydrogenphosphate) tetrahydrate.
The 31P NMR spectrum contains only one single signal at 0.020 ppm and is due to the
proton in the OH group attached to the phosphorus atom of monohydrogenphosphate. As no
other peaks are observed, it is clear that the compound has been successfully synthesized and
this suggests that it is a pure material.
3.5 Thermal analysis
The TGA and DTA traces of 4M+22M+5P4H2O are shown in Fig. 9. These
thermograms were recorded to evaluate the thermal stability of the salts.

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2
100
90
80
70
60
50
40
30
20
1
0
-1
-2
-3
-4
-5
240.8°C
268.6°C
183.5°C
80.8°C
309.1°C
327.6°C
569.5°C
372.6°C
100
200
300
400
500
600
700
800
Temperature (°C)
Fig. 9. TGA-DTA thermograms of melaminium pentakis(monohydrogenphosphate)
tetrahydrate.
These thermograms show that the decomposition of the title compound takes place
through four stages involving dehydration and decomposition. The first weight loss region is
due to anhydrous salt formation. Moreover, the first stage of decomposition takes place in the
temperature range from 78.3 °C to 85.71 °C with a small weight loss of 0.45 % suggesting
that hydrated water of 4M+22M+5P4H2O is eliminated from the structure of the compound.
The corresponding DTA peak occurs at 80.8 1°C. The second and third stages of the
decomposition takes place in the temperature ranges from 223.15 °C to 289.73 °C and from
290.1 °C to 405.93 °C with a significant weight loss of 5.31 % and 19.53 % accompanied by
an elimination of melaminium+ and melaminium2+ cations. These stages are evidenced by
seven exothermic peaks. These corresponding DTA peaks appear at 240.8, 268.6, 284.4,
297.9, 309.1, 327.6 and 372.6 °C. The last stage of decomposition which takes place in the
temperature range from 405.93 °C to 643.52 °C with a significant weight loss of 42.10 %
accompanied by a DTA peak at 569.5 °C is due to the elimination of
monohydrogenphosphate anions with a final residue of 25 %.
The DTA thermogram shows an exothermic peak at about 183.5 °C which is the phase
transition where the four water molecules are eliminated in this stage.
4. Conclusion
A new compound melaminium phosphate 4M+22M+5P4H2O was synthesized using
melamine as the starting material. The single crystal obtained by a re-crystallization process

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in water at room temperature and its structure was investigated by means of the single crystal
X-ray diffraction method. It has a white color and belongs to a non-centrosymmetric system
P 21 with a prism geometry. The optical transmission analysis showed that the grown crystals
were optically transparent and the lower cut off wavelength is 290 nm. The FT-IR spectrum
clearly indicated the presence of functional groups in the complex. Several stretching and
deformation modes confirmed the presence of extensive intermolecular hydrogen bonding in
the crystal. FT-NMR spectrum analysis confirmed the molecular structure of the compound.
TGA-DTA results indicated that 4M+22M+5P4H2O has a better thermal stability which
makes it suitable for thermal applications. Moreover these complexes are very promising
light emitting materials due to their good thermal stability. Further research has to be carried
out and can be extended to several industrial and research applications.
Acknowledgements
The author (H. Ait Youcef) acknowledges Professor Lahcène Ouahab ‘‘Director of
Research, CNRS, member of the European Academy of Sciences, Chemical Science Institute
of Rennes, University of Rennes 1. The Organometallic team and Molecular Materials for
helping us in the crystallographic study.

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Figures captions:
Fig. 1. Reaction scheme of Melaminium pentakis (monohydrogenphosphate) tetrahydrate.
Fig. 2. Photograph of Melaminium pentakis (monohydrogenphosphate) tetrahydrate.
Fig. 3. Packing of the molecules in elementary unit cell.
Fig. 4. UV–Vis spectrum of melaminium pentakis (monohydrogenphosphate) tetrahydrate.
Fig. 5. FTIR spectrum of melaminium pentakis (monohydrogenphosphate) tetrahydrate.
Fig. 6. 1H NMR spectrum of melaminium pentakis (monohydrogenphosphate) tetrahydrate.
Fig. 7. 13C NMR spectrum of melaminium pentakis (monohydrogenphosphate) tetrahydrate
Fig. 8. P NMR spectrum of melaminium pentakis (monohydrogenphosphate) tetrahydrate.
Fig. 9. TGA-DTA thermograms of melaminium pentakis (monohydrogenphosphate)
tetrahydrate.
Tables captions:
Table 1
Crystallographic data and structure refinement parameters of melaminium pentakis
(monohydrogenphosphate) tetrahydrate
Table 2
Vibration band assignment of melaminium pentakis (monohydrogenphosphate) tetrahydrate

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Table 1
Crystallographic data and structure refinement parameters of melaminium pentakis
(monohydrogenphosphate) tetrahydrate.
+2
+
2-
Empirical formula
Formula weight (g/mol)
Crystal system
Space group
a (Å)
b (Å)
c (Å)
α (°)
4C3H8N6 .2C3H7N6 .5HPO4 .4H2O
1318.79
Monoclinic
P21
11.3008 (10)
20.9798 (2)
12.2679 (10)
90
β (°)
γ (°)
117.2360 (10)
90
Temperature (K)
V (Å3)
Z
293 (2)
2586.10 (4)
2
λ M0Kα (Å)
Dcalc (Mg /m)
µ (mm-1)
0.71073
1.629
0.291
F(000)
1338
Crystal size (mm3)
Crystal colour/habit
θ Range (°)
hkl ranges
0.1 x 0.1 x 0.1
White/ prism
5.12–27.50
-14/14, -27/26, -15/15
0.971/0.971
11513/11513[Rint=0.0000]
99.0%
Absorpt. correct. (Tmin; Tmax
)
Reflections collected/unique
Completeness to 2θ = 27.50
Refinement method
Full-matrix least-squares on F2
11513/1/768
1.014
Data/restrains/parameters
Goodness-of-fit on F2
Final R indices[I>2σ(I)]
R indices (all data)
Largest difference peak and hole (e/Å3)
Independent reflections
R1= 0.0314, ѡR2 = 0.0838
R1= 0.0301, ѡR2 = 0.0825
+0.387, -0.343
6030

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Table 2
Vibration band assignment of melaminium pentakis (monohydrogenphosphate) tetrahydrate.
FT-IR (Wave number cm−1)
3420
Assignments
O–H stretching of water
References
[61]
3379
3220
3158
3020
2837
NH2 symmetric stretching
O–H···O stretch
[36]
N–H···O and N–H···N stretching
O–H···O and N–H···O asymmetric stretching
Combination tone: NH2 asymmetric stretch-
side chain out of plane C–N bend
P–OH stretching
[36]
[62]
2712
2500
2430
2340
O–H···O stretch
O–H···O stretch, with water molecule
Vibrations of hydrogen bonds formed by
water molecules
[63,64]
1739
1680
1664
1620
NH2 bending type of vibration
H2O in plane bend
NH2 bending
[36]
[63]
[36]
[40]
[39]
[63]
[36]
[36]
Ring: quadrant stretching;
NCN bend + ring deformation
H2O in plane bend
Side-chain asymmetric C–N stretching
Side-chain asymmetric C–N stretching
N–H deformation vibration
Ring: semi-circle stretching + exogenous C–N
contract
1584
1538
1510
1490
1405
[40,41]
1333
1246
1150
1108
Ring: semi-circle stretch
P=O stretching
NH2 rocking
P–O asymmetric stretching
[41]
[65]
[36]
[66]
1050
1021
991
Triazine ring vibration breath
P–O symmetric stretching
Triazine ring N,in phase radial type of
vibration
[36]
[66]
[38,41]
958
860
901
784
772
P–O–H deformation vibration
P–O(H) stretching of HPO4
O–H of water in plane bending
Ring sextant out of plane bending
Ring bend out of plane bending
[66]
[36]
[39,44]
[39]
691
612
576
544
505
Symmetric type triazine ring
Ring bending
C–N bending vibration
Side-chain in plane C–N bend
H2O wagging
[36]
[36]

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H I G H L I G H T S
A new Tetrakis(M2+)Bis(M+)Pentakis(hydrogenphosphate)Tetrahydrate was
synthesised.
The title compound was characterized by SXRD,UV-vis, FTIR, NMR and
TGA-DTA studies.
It crystallizes in monoclinic crystal system and the space group is P 21.
The protonation of triazine caused dramatic changes in the frequencies of the
ring.
The new material has more thermal stability up to 200 °c.