FT-IR and FT-Raman spectroscopies and DFT calculations of 2,2-dimethyl-5-(4H-1,2,4-triazol-4-ylaminomethylene)-1,3-dioxane-4,6-dione monohydrate

Article abstract of DOI:10.1016/j.molstruc.2012.12.058

In this work we present a study of the vibrational spectra of 2,2-dimethyl-5-(4H-1,2,4-triazol-4-ylaminomethylene)-1,3-dioxane-4,6-dione monohydrate, C₉H₁₀N₄O₄?H ₂O. The FT-IR and FT-Raman spectra of the crystal were recorded at room temperature in the regions 400-4000 cm^-1 and 50-4000 cm ^-1, respectively. Vibrational wavenumbers and wave vector were predicted using density functional theory calculations with the B3LYP functional and 6-31G(d,p) basis set. The descriptions of the normal modes were made after considering the Potential Energy Distribution (PED). A comparison with experimental spectra allowed us to assign all of the normal modes of the crystal.

Full text of DOI:10.1016/j.molstruc.2012.12.058

Journal of Molecular Structure 1038 (2013) 170–176
Contents lists available at SciVerse ScienceDirect
Journal of Molecular Structure
journal homepage: www.elsevier.com/locate/molstruc
FT-IR and FT-Raman spectroscopies and DFT calculations of
2,2-dimethyl-5-(4H-1,2,4-triazol-4-ylaminomethylene)-1,3-dioxane-4,6-dione
monohydrate
a
a
a
a
b
b
G.M.M. Sampaio , A.M.R. Teixeira , H.D.M. Coutinho , D.M. de Sena Junior , P.T.C. Freire , P.E.S. Caselli ,
G.O.M. Gusmão , R.R.F. Bento , L.E. Silva d
b
c,
⇑
a
Universidade Regional do Cariri, 63010-970 Crato, Brazil
Universidade Federal do Ceará, 60455-760 Fortaleza, Brazil
Universidade Federal de Mato Grosso, 78060-900 Cuiabá, Brazil
Universidade Federal do Paraná, Setor Litoral, Matinhos 83260-000, Brazil
b
c
d
h i g h l i g h t s
"
"
"
"
"
We study the vibrational spectra of C
We furnish the descriptions of the normal modes considering the Potential Energy Distribution (PED).
We present calculated and theoretical data on geometric parameters of the molecule.
We give detailed description of the assignments of the vibrational modes of C
The first time the Potential Energy Distribution (PED) is being presented for this synthetic substance.
9
H
10
N
4
O
4
ÁH
2
O molecule through Raman and infra red spectroscopies.
H
9 10
N O
4 4
ÁH O.
2
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 9 October 2012
Received in revised form 30 December 2012
Accepted 30 December 2012
Available online 11 January 2013
In this work we present a study of the vibrational spectra of 2,2-dimethyl-5-(4H-1,2,4-triazol-4-ylami-
nomethylene)-1,3-dioxane-4,6-dione monohydrate, C
9
H
10
N
4
O
4
ÁH
2
O. The FT-IR and FT-Raman spectra of
À1
À1
the crystal were recorded at room temperature in the regions 400–4000 cm and 50–4000 cm , respec-
tively. Vibrational wavenumbers and wave vector were predicted using density functional theory calcu-
lations with the B3LYP functional and 6-31G(d,p) basis set. The descriptions of the normal modes were
made after considering the Potential Energy Distribution (PED). A comparison with experimental spectra
allowed us to assign all of the normal modes of the crystal.
Keywords:
Raman scattering
IR spectroscopy
Normal modes
Ó 2013 Elsevier B.V. All rights reserved.
C
H
9 10
N
4
O
4
ÁH
2
O crystal
1
. Introduction
The synthesis of isolated pure substances has become a tool of
the other hand, cyclic 1,3-diones like Meldrum’s acid (2,2-di-
methyl-1,3-dioxane-4,6-dione) and their 5-arylaminemethylene
analogs play an important role in heterocyclic chemistry as pivotal
intermediates to access cyclic products [8].
great importance to the development of drugs with enhanced
pharmacological properties. Nowadays, the use of molecular mod-
eling contributes markedly to the discovery of new drugs, which
are safer and more efficient. The compound 1,2,4-triazole and its
derivatives have been used as starting materials for the synthesis
of many heterocycles [1]. Studies indicate that the 1,2,4-triazole
group is associated with anti-inflammatory action [2], and also
with pharmacological activities, such as antiviral [3], analgesic
Derivatives of Meldrum’s acid have proven to be valuable re-
agents and intermediates in the synthesis of complex organic com-
pounds such as natural products and their analogs [9]. The search
for a study to demonstrate the biological activity of 5-aminometh-
ylene Meldrum’s acid derivatives led to a patent in 1965 [10]. In
addition, different heterocyclic rings were condensed to the 5-
methoxymethylene Meldrum’s acid in order to evaluate their po-
tential biological activity as antileishmanicidal, antitrypanosomal
and antiviral agent [8,11]. Furthermore, several compounds, natu-
ral or synthetic, can modify the antibiotic activity and also the phe-
notype of the bacterial strains, reversing the resistant and
[
4], antimicrobial [5], antidepressant [6] and antifungal [7]. On
⇑
Corresponding author. Tel.: +55 65 3615 8743; fax: +55 65 3615 8734.
E-mail address: ricardobento@fisica.ufmt.br (R.R.F. Bento).
0
022-2860/$ - see front matter Ó 2013 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.molstruc.2012.12.058

G.M.M. Sampaio et al. / Journal of Molecular Structure 1038 (2013) 170–176
171
intermediary phenotype to the sensitive phenotype, as demon-
strated by the derived compounds of 4-chloro-5-heteroimine-
dithiazoles, against the Escherichia coli, Staphylococcus aureus and
Pseudomonas aeruginosa strains [12].
Many heterocyclic derivatives of Meldrum’s acid (2,2-dimethyl-
1
,3-dioxane-4,6-dione) have been prepared and studied from the
synthetic and structural point of view [11], although their vibra-
tional properties have not received the same attention. In order
to fill this gap, the present work reports a study of vibrational spec-
tra of 2,2-dimethyl-5-(4H-1,2,4-triazol-4-ylaminomethylene)-1,3-
dioxane-4,6-dione monohydrate, C
9
H
10
N
4
O
4
ÁH
2
O, with support of
theoretical calculations using density functional theory. As a con-
sequence, we were able to assign the vibrational modes of the crys-
tal this synthetic compound.
2
. Experimental
Fig. 2. Unit cell of C
bonds.
9
H
10
N
4
O
4
ÁH
2
O with dashed lines representing the hydrogen
The crystal structure of 2,2-dimethyl-5-(4H-1,2,4-triazol-4-
ylaminomethylene)-1,3-dioxane-4,6-dione monohydrate, C
9 10 4-
H N
O
4
ÁH O, an aminomethylene derivative of Meldrum’s acid, was re-
2
(
B3LYP) and the basis set 6-31G, augmented by d polarization func-
tions on heavy atoms and p polarization functions on hydrogen
atoms, were used [15–17]. The initial molecular structure of C
ÁH O used in the DFT calculations corresponds to a single mol-
cently reported [13]. Crystalline samples of this compound were
obtained after heating a solution of Meldrum’s acid (36 mmol) in
thimethyl orthoformate (50 mL) under reflux for 2 h, and adding
the corresponding arylamine (30 mmol). Reflux was kept for addi-
tional 30 min. The material thus formed was filtered and washed
with methanol.
9
H
10-
N
4
O
4
2
ecule of the unit cell described in Ref. [13]. The output file
contained the optimized structure, the vibrational frequencies in
the harmonic approximation, and the atomic displacements for
each mode. The Potential Energy Distribution (PED) of the normal
modes was calculated using the GAR2PED program [18]. The nor-
mal mode analysis was performed and the PED was calculated
along the internal coordinates using localized symmetry [19,20].
For this purpose a complete set of 84 internal coordinates were de-
fined using Pulay’s recommendations [19]. The calculated vibra-
tional wave numbers were adjusted to compare with
experimental Raman and IR frequencies.
À1
FT-Raman spectrum, in the wavenumber region from 50 cm
À1
to 4000 cm , was taken using a Bruker RFS100/S FTR system
and a liquid nitrogen cooled Ge D418-T detector, with a Nd:YAG la-
ser emitting at 1064 nm as excitation source. Laser power was set
to 150 mW, nominal resolution to 4 cm , and accumulation of 60
scans per spectra. Slightly compacted powder samples were con-
fined in screw cap standard chromatographic glass vials.
Infrared spectrum was obtained by using a Bruker Equinox/55
Fourier Transformed infrared (FT-IR) spectrometer equipped with
a DTGS (deuterated triglycine sulfate) detector and a KBr beamsp-
litter. The wavenumber region covered in the mid-IR spectrum goes
from 400 cm to 4000 cm with samples grinded in an agate mor-
tar to minimize scattering on the particle surface, and mixed with
KBr until a uniform mixture was obtained to form a pellet. The res-
À1
À1
À1
4
. Results and discussion
The molecular structure of 2,2-dimethyl-5-(4H-1,2,4-triazol-4-
À1
olution was of 4 cm . IR spectra were recorded and treated using
spectroscopic software OPUS, from Bruker.
ylaminomethylene)-1,3-dioxane-4,6-dione monohydrate, C
O
9 10 4-
H N
4
2
ÁH O comprises two rings, named here as R1 and R2. R1 is a five-
membered ring formed by atoms C1, C2, N1, N2 and N3 which
comes from a 1,2,4 triazole group. R2, on its turn, is a six-
membered ring formed by atoms C4 to C7, O2 and O3, originated
from Meldrum’s acid (2,2-dimethyl-1,3-dioxane-4,6-dione). The
corresponding ball and stick model, with atom numbering, used
3
. Computational method
The Density Functional Theory (DFT) algorithm was used in the
calculation, and all the calculations in this work were performed by
using Gaussian 03 software package [14]. The hybrid functional
to describe the C
H
9 10
N
4
O
4
2
ÁH O structure is shown in Fig. 1.
Fig. 1. Representation of the molecular structure of C
9
H
10
4
N O
4 2
ÁH O.

1
72
G.M.M. Sampaio et al. / Journal of Molecular Structure 1038 (2013) 170–176
The crystal structure of C
clinic system, with space group P2
a = 18.012 Å, b = 5.356 Å, c = 12.937 Å, b = 108.786° [13]. The distri-
bution of the four molecules of C O in the unit cell is
shown in Fig. 2, where the dashed lines represent the hydrogen
bonds among the molecules, which are responsible for the stabil-
ization of the structure in the solid state, as occur with several
other organic materials. The nitrogen atoms of ring R1 forms
9
H
10
N
4
O
4
ÁH
2
O belongs to the mono-
hydrogen bonds with one of the oxygen atoms of water molecule
while the other oxygen form a hydrogen bond with the N4 atom
of the C H N O molecule. Additionally, some internal hydrogen
9 10 4 4
bonds are formed, as those between the N4 atom and the oxygen
of the ring R2.
It is well described in the literature that the biological activity,
as well as the geometry of molecules, are influenced by internal
hydrogen bonds. Furthermore, this issue is the subject of current
1
/c, Z = 4, and lattice parameters:
9
H
10
N
4
O
4
ÁH
2
Table 1
Comparative tables of geometric parameters (calculated and experimental) of C
H
9 10
4
N O
4 2
ÁH O.
Bond lengths
Exp. (Å)
Calc. (Å)
Bond lengths
Exp. (Å)
Calc. (Å)
C1–N1
C1–N3
C1–H1
N1–N2
N2–C2
C2–N3
C2–H2
N3–N4
N4–C3
N4–H10
C3–C4
C3–H3
C4–C7
C4–C5
C5–O1
1.293
1.348
0.930
1.387
1.299
1.346
0.930
1.391
1.317
0.860
1.367
0.930
1.437
1.451
1.207
Exp. (°)
109.7
125.1
125.1
107.6
106.6
110.1
124.9
124.9
105.9
127.0
127.0
119.5
125.8
114.7
126.4
116.8
116.8
121.8
117.2
120.8
117.9
126.3
115.8
118.3
Exp. (°)
0.6
1.306
1.375
1.080
1.390
1.306
1.376
1.080
1.384
1.340
1.036
1.378
1.087
1.456
1.474
1.211
Calc. (°)
110.0
127.1
122.9
107.6
107.6
110.0
127.1
122.9
104.9
127.5
127.4
119.2
126.2
114.6
128.5
115.1
116.4
123.4
115.8
120.5
119.4
125.3
115.3
119.5
Calc. (°)
0.4
C5–O2
O2–C6
C6–O3
C6–C8
C6–C9
O3–C7
C7–O4
C8–H4
C8–H5
C8–H6
C9–H7
C9–H8
C9–H9
O5–H11
O5–H12
Bond angle
O2–C6–O3
O2–C6–C8
O3–C6–C8
O2–C6–C9
O3–C6–C9
C8–C6–C9
C7–O3–C6
O4–C7–O3
O4–C7–C4
O3–C7–C4
C6–C8–H4
C6–C8–H5
H4–C8–H5
C6–C8–H6
H4–C8–H6
H5–C8–H6
C6–C9–H7
C6–C9–H8
H7–C9–H8
C6–C9–H9
H7–C9–H9
H8–C9–H9
H11–O5–H12
1.365
1.433
1.436
1.500
1.502
1.362
1.211
0.960
0.960
0.960
0.960
0.960
0.960
0.910
0.960
Exp. (°)
110.2
110.00
109.9
106.5
106.3
113.8
117.8
117.8
125.6
116.6
109.5
109.5
109.5
109.5
109.5
109.5
109.5
109.5
109.5
109.5
109.5
109.5
107.0
1.369
1.431
1.446
1.527
1.517
1.356
1.224
1.092
1.092
1.093
1.092
1.092
1.092
0.973
0.966
Calc. (°)
111.5
110.8
109.4
106.3
105.8
113.6
119.4
118.3
125.0
116.6
109.6
110.0
111.0
111.0
108.5
108.6
109.8
109.5
109.1
110.0
109.3
109.2
104.7
Bond angle
N1–C1–N3
N1–C1–H1
N3–C1–H1
C1–N1–N2
C2–N2–N1
N2–C2–N3
N2–C2–H2
N3–C2–H2
C2–N3–C1
C2–N3–N4
C1–N3–N4
C3–N4–N3
C3–N4–H10
N3–N4–H10
N4–C3–C4
N4–C3–H3
C4–C3–H3
C3–C4–C7
C3–C4–C5
C7–C4–C5
O1–C5–O2
O1–C5–C4
O2–C5–C4
C5–O2–C6
Torsion angle
N3–C1–N1–N2
C1–N1–N2–C2
N1–N2–C2–N3
N2–C2–N3–C1
N2–C2–N3–N4
N1–C1–N3–C2
N1–C1–N3–N4
C2–N3–N4–C3
C1–N3–N4–C3
N3–N4–C3–C4
N4–C3–C4–C7
N4–C3–C4–C5
C3–C4–C5–O1
C7–C4–C5–O1
C3–C4–C5–O2
Torsion angle
C7–C4–C5–O2
O1–C5–O2–C6
C4–C5–O2–C6
C5–O2–C6–O3
C5–O2–C6–C8
C5–O2–C6–C9
O2–C6–O3–C7
C8–C6–O3–C7
C9–C6–O3–C7
C6–O3–C7–O4
C6–O3–C7–C4
C3–C4–C7–O4
C5–C4–C7–O4
C3–C4–C7–O3
C5–C4–C7–O3
Exp. (°)
Calc. (°)
À7.1
À5.4 (3)
0.1
0.2
159.2 (2)
À23.0 (3)
49.5 (2)
161.2
À21.5
46.2
À0.8
À0.7
1.1
0.9
176.18
À1.1
176.3
À0.8
À71.8 (2)
164.38 (18)
À49.7 (2)
71.7 (2)
À164.71 (18)
À159.60 (18)
23.6 (3)
À75.4
161.1
À44.2
78.0
À159.3
À164.8
17.7
À176.12
À176.2
77.5
86.9
À108.4
À177.2
2.8
À98.7
À178.8
2.7
177.6
À2.6
177.0
À4.5
3.1 (3)
5.6
À171.5 (2)
179.60 (18)
5.0 (3)
À168.5
177.2
8.8
172.2
179.8
170.0
178.5
Hydrogen-bond geometry (Å, °)
D–HÁ Á ÁA
D–H
Exp.
HÁ Á ÁA
DÁ Á ÁA
D–HÁ Á ÁA
Calc.
Exp.
Calc.
Exp.
Calc.
Exp.
Calc.
N4–H10Á Á ÁO4
N4–H10Á Á ÁO5
0.9
0.9
1.0
1.0
2.2
2.0
2.3
1.8
2.8
2.7
2.9
2.8
119.6
142.0
112.3
164.8

G.M.M. Sampaio et al. / Journal of Molecular Structure 1038 (2013) 170–176
173
research in chemistry, due to the influence of these interactions in
the design of new biologically active substances, affecting mem-
brane transport and the distribution of drugs within biological sys-
tem. In general terms the formation of ligand–protein complexes
depends on hydrogen bonding. As it is well known, hydrogen bond
contributes to the orientation of the ligand associated by a confor-
mational distortion of the molecules and recognition of substrates,
inhibitors, agonists and antagonists, among others [21–25].
FT-Raman and FT-IR spectroscopies (the third and fourth columns,
respectively); and the fifth column gives the assignment of the all
bands appearing in both Raman and infra red spectra. The vibra-
tional assignments of the normal modes were made with regard
to the PED, where values greater than 10% only are considered.
The percent contribution of the PED to each vibrational mode is gi-
ven in parentheses in the fourth column.
The symbols employed in the classification of the normal modes
The molecule C
9
H
10
N
4
O
4
ÁH
2
O has 30 atoms, and so there are 90°
are as follows: r, s, sc and wag stand for rocking, torsion, scissoring
and wagging vibrations, respectively. The symbol d is used to indi-
cate a bending and when associated with the subscript ‘out’ refers
of freedom. Excluding the translational and rotational modes, there
are 84 vibrational modes for the hydrate. In the unit cell there are
four units of the hydrate C
freedom and thus 354 vibrational modes are expected. From these,
three are acoustic modes and 351 are optical modes. The modes of
9
H
10
N
4
O
4
ÁH
2
O, accounting for 360° of
s
to an out-of-plane deformation. Finally, m and mas are used to indi-
cate symmetric and anti-symmetric stretching, respectively. With
regard to the intensity of the Raman and of the infrared bands
we have used the following abbreviations: vs (very strong), s
(strong), m (medium), w (weak) and vw (very weak).
A
g
and B
g
irreducible representations of the factor group C2h are
and B symmetries are infrared
Raman active, while modes with A
u
u
active. Assuming that the weakness of the intermolecular coupling
causes negligible factor group splitting, the assignment task is sim-
plified to that of the molecular modes.
Now we discuss the main calculated and observed vibrations of
C
9
H
10
N
4
O
4
2
ÁH O. The calculated values for the wavenumbers at the
DFT level contain known systematic errors due to the neglect of
electron correlation, resulting in overestimates of about 10–20%.
Therefore, it is necessary to calculate a suitable scale factor (f) to
achieve a better agreement with the experimental values. Follow-
ing the procedure described by Wong [26] and Scott and Radom
[27], f was calculated by fitting the theoretical values to the exper-
imental ones (from FT-Raman spectrum). After successive adjust-
ments, f was found to be 0.9495 with the overall root mean
Table 1 shows bond distances, bond angles and dihedral angles
for the hydrate C
9
H
10
N
4
O
4
ÁH
2
O, for the optimized structure (Calc.)
and that obtained from X-ray analysis (Exp.) [13]. The agreement
between the optimized and experimental crystal structure is quite
good, showing that the geometry optimization reproduces the
experimental conformation almost exactly.
The FT-Raman and FT-IR spectra of polycrystalline samples of
À1
the substance C
9
H
10
N
4
O
4
ÁH
2
O are shown in Figs. 3a and b, respec-
square error for this scale factor of 56 cm . In Table 2, the scaled
tively. From the FT-Raman spectrum we observe that modes below
wavenumbers (xscal) were obtained by multiplying the calculated
À1
2
00 cm – some of them associated to external modes and others
values ( cal) by f. The assignments of the respective molecular
x
to internal modes as discussion below – are the most intense in all
spectral range, at least from 0 to 1750 cm interval.
vibrations are given in the last column.
À1
Analysis of the normal modes from the crystal shows that most
of the bands in the FT-Raman and FT-IR spectra consist of com-
bined vibrational modes. The out of plane deformation are mainly
Table 2 lists a detailed description of the assignments of the
vibrational modes of C
9
H
10
N
4
O
4
ÁH
2
O. The calculated wavenumber
À1
À1
À1
values, not scaled, are given in the first column, while the calcu-
lated and scaled wavenumbers – whose meaning will be furnished
below – are given in the second column. We also present the
experimental wavenumber values for the crystal obtained by
present in the region between 30 cm
also be observed until
6
x
cal 6 900 cm , but can
xcal = 1332 cm . The torsional modes are
observed in the region of calculated frequencies between
À1
À1
104 cm and 684 cm . However, vibrations related to the methyl
(
a)
(
b)
À1
À1
Fig. 3. Vibrational spectra of C
associated with the atomic displacements in Fig. 4a and b, respectively.
9
H
10
N
4
O
4
ÁH
2
O crystal at room temperature: (a) FT-Raman and (b) FT-IR. The vertical arrows in (a), at 207 cm , and (b), at 930 cm , are

1
74
G.M.M. Sampaio et al. / Journal of Molecular Structure 1038 (2013) 170–176
Table 2
Calculated vibrational wavenumbers (in cm ), scaled values for f = 0.9495, experimental Raman and IR bands positions in units of cm , and assignment of vibrational modes.
À1
À1
x
calc
x
scal
x
FT-Raman
x
FT-IR
Assignment with PEDa (%)
3
3
3
5
7
0
28
33
37
49
74
99
115
123
152
191
206
209
237
245
246
281
318
326
367
381
398
401
411
479
483
498
558
593
606
611
649
685
704
744
765
791
806
d
d
d
d
d
out (C7C4C3C5) (73) + dout (C3N4HN3) (18)
out (C3N4HN3) (89)
out (C3N4HN3) (79) + dout (C7C4C3C5) (14)
out (C2N3N4C1) (72)
out (C3N4HN3) (90)
s (C4C5O2C6)] (95)
5
9
2
8
61 m
74 vs
1
04
21
30
60
01
17
20
50
58
59
96
35
43
87
01
19
22
33
05
09
25
88
25
38
44
84
21
41
84
06
33
49
71
00
35
45
52
104 vs
115 vs
125 vs
148 m
161 m
185 m
207 w
R2[
R2[d (C7C4C5;O2O3C6)] (32) + dout (C2N3N4C1) (27) + dout (C7C4C3C5) (18)
out (C7C4C3C5) (42) + R2[ (C4C5O2C6)] (18) + R2[d (C4O2C5;O3C4C7)] (13)
R2[ (C4C5O2C6)] (20) + dout (C3N4HN3) (20) + dout (C2N3N4C1) (13) + R2[d (C4O2C5;O3C4C7)] (13)
1
1
1
2
2
2
2
2
2
2
3
3
3
4
4
4
4
5
5
5
5
6
6
6
6
7
7
7
8
8
8
8
9
9
9
9
d
s
s
d
d
R2[
out (C7C4C3C5) (65) + dout (C2N3N4C1) (15)
out (C7C4C3C5) (84) + dout (C3N4HN3) (11)
s (C8H ;C9H )] (79) + dout (C7C4C3C5) (16)
3 3
214 w
R2[d (C7C4C5;O2O3C6)] (70) + dout (C2N3N4C1) (13)
226 m
263 m
295 w
317 vw
328 vw
346 w
360 vw
389 m
396 m
408 m
432 m
447 vw
487 vw
510 m
529 m
550 vw
564 vw
581vw
615 w
R2[
R2[
R2[
d
d
s
s
s
(C8H
(C8H
3
; C9H
;C9H
3
)] (33) + R2[d (C4O2C5;O3C4C7)] (21) + dout (C3N4HN3) (17)
)] (42) + d (HO5H) (29) + dout (C3N4HN3) (13)
3 3
(C8H ;C9H )] (26)
3
3
(C4C5O2C6)] (41) + R2[d (C4O2C5;C6C7O3)] (26) + R2[
s
out (C7C4C3C5) (24) + R2[d (C4O2C5;O3C4C7)] (17) + d (HN4N3) (16)
out (C7C4C3C5) (59) + dout (C3N4HN3) (35)
R2[s (C4C5O2C6)] (60) + dout (C3N4HN3) (17) + d (C6C8H) (11)
d
d
d
d
out (C7C4C3C5) (51) + dout (C3N4HN3) (28)
out (C7C4C3C5) (58) + dout (C3N4HN3) (15) + dout (C4C3HN4) (14)
out (C3N4HN3) (81)
412 m
434 s
out (C7C4C3C5) (61) + dout (C3N4HN3) (22) + dout (C4C3HN4) (11)
R2[d (C4O2C5;C6C7O3)] (49) + R2[d (C4O2C5;O3C4C7)] (26) + dout (C7C4C3C5) (11)
R2[d (C7C4C5;O2O3C6)] (95)
R2[d (C7C4C5;O2O3C6)] (78) + dout (C7C4C3C5) (17)
R1[
R1[
R1[
509 m
528 w
s
s
s
(N2N1C1N3)] (43) + d (HN4N3) (30) + dout (C2N3N4C1) (13)
(N2N1C1N3)] (54) + dout (C2N3N4C1) (20)
(N2N1C1N3)] (44) + dout (C2N3N4C1) (26)
d
out (C7C4C3C5) (49) + R2[d (C7C4C5;O2O3C6)] (23)
R1[ (N2N1C1N3)] (57)+R1[dout (N3C1HN1)] (24)
out (C4C3HN4) (63) + R2[ (C4C5O2C6)] (22) + dout (C3N4HN3) (13)
584 s
613 s
634 m
644 m
669 w
735 s
s
d
d
d
s
634 m
648 s
675 w
736 m
840 m
856 w
out (C7C4C3C5) (46) + R2[d (C7C4C5;O2O3C6)] (31)
out (C7C4C3C5) (92)
R1[dout (N3C1HN1)] (73) + R1[dout (N2C2HN3)] (25)
R1[dout (N3C1HN1)] (74) + R1[dout (N2C2HN3)] (21)
R1[dout (N3C1HN1)] (46) + R1[dout (N2C2HN3)] (11)
d
d
798 s
827
855
888
897
904
950
963
972
843 m
873 m
930 s
951 m
985 m
out (C3N4HN3) (65) + dout (C4C3HN4) (23)
out (C7C4C3C5) (31) + R2[d (C7C4C5;O2O3C6)] (23)+ dout (C3N4HN3) (18) + R2[d (C7C4C5;O2O3C6)] (13)
892 m
932 m
941 m
985 m
994 m
1006 m
1017 m
1063 m
1097 vw
1137 m
1168 vw
1200 m
1218 m
1234 vw
1243 vw
1269 m
1280 m
1295 m
1325 m
1356 m
1384 m
1401w
1438 m
1463 vs
R1[d (C1N3C2N2N1)] (83)
r (C8H ) (30) + R2[d (C7C4C5;O2O3C6)] (15) + d (C9H
R2[d (C7C4C5;O2O3C6)] (24) + R2[d (C4O2C5;C6C7O3)] (22)
R1[d (C2N2N3)] (37) + R1[d (C1N1N3)] (17) + R1[ (N1N2)] (15)
out (C4C3HN4) (51) + R2[d (C7C4C5;O2O3C6)] (27) + dout (C7C4C3C5) (11)
r (C8H ) (53) + r (C9H ) (22)
out (C4C3HN4) (87)
out (C4C3HN4) (80)
3
3
) (12)
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
3
3
001
014
024
041
048
070
156
222
224
235
255
290
301
332
341
405
420
435
439
491
492
508
510
514
518
545
656
681
776
833
066
075
m
1001s
1021 m
1057 s
d
3
3
988
995
d
d
1016
1098
1160
1162
1173
1192
1225
1235
1265
1273
1334
1348
1363
1366
1416
1417
1432
1434
1438
1441
1467
1572
1596
1686
1740
2911
2920
1136 m
R1[d (C2N2N3)] (43) + R1[d (C1N3C2N2N1)] (20) + R1[m (C1N3)] (12) + R1[d (C1N1N3)] (11)
d (HN4N3) (16) + R1[d (C1N1N3)] (16) + d (N4C3C4) (16)
R1[d (C1N1N3)] (89)
R1[d (C2N2N3)] (62) + R1[d (C1N1N3)] (25)
R2[d (C7C4C5;O2O3C6)] (83)
R2[d (C7C4C5;O2O3C6)] (23) + R2[d (C4C5C7)] (20) + R1[d (C1N1N3)] (12)
d (N4C3C4) (22) + R2[d (C7C4C5;O2O3C6)] (22) + d (HN4N3) (12)
R2[d (C7C4C5;O2O3C6)] (57) + d (N4C3C4) (32)
1202 w
1218 s
1268 s
1287 vs
d
out (C3N4HN3) (35) + R1[m (C1N3)] (24) + R1[d (C1N3C2N2N1)] (19)
1323 w
1355 m
1380 s
1390 m
1437 w
1462 m
d (N4C3C4) (46) + R2[d (C7C4C5;O2O3C6)] (23) + d (HN4N3) (23)
d (HN4N3) (38) + R2[d (C7C4C5;O2O3C6)] (24) + d (N4C3C4) (16)
wag (C9H
d (HN4N3) (54) + wag (C8H
d (HN4N3) (78)
3
) (69) + wag (C8H
3
(25)
3
) (18)
sc (C9H
sc (C9H
3
) (74) + sc (C8H
) (49) + sc (C8H
3
) (14)
3
3
) (16) + d (HN4N3) (14)
1474 m
1472 m
d (HN4N3) (72)
d (HN4N3) (64) + R2[d (C7C4C5;O2O3C6)] (21)
sc (C9H ) (52) + d (HN4N3) (15)
d (HN4N3) (51) + R1[d (C2N2N3)] (23)
d (HN4N3) (34) + R1[d (C1N1N3)] (24) + R1[d (C2N2N3)] (20)
d (HN4N3) (53) + d (HO5H) (33)
d (HN4N3) (50) + d (HO5H) (42)
R2[
R2[d (C7C4C5;O2O3C6)] (76)
m
m
1517 m
1533 w
1602 m
1643 vw
1678 vw
1701vs
1737 vs
2749 w
2863 w
1517 w
1539 vw
1597 s
1645 vw
1675 m
1699 vs
1736 s
3
m (C7O4)] (61) + R2[d (C7C4C5;O2O3C6)] (15) + R2[d (C4O2C5;C6C7O3)] (12)
s
s
(C8H
(C9H
3
) (92)
) (88)
3

G.M.M. Sampaio et al. / Journal of Molecular Structure 1038 (2013) 170–176
175
Table 2 (continued)
x
calc
x
scal
x
FT-Raman
x
FT-IR
Assignment with PEDa (%)
3145
3153
3161
3162
3197
3211
3283
3288
3721
3872
2986
2994
3001
3002
3036
3049
3117
3122
3533
3676
2886 vw
2920 m
2947 vs
2993 m
3002 s
3012 s
3056 w
3133 s
m
m
m
m
m
m
R1[
R1[
m
m
as (C8H
as (C8H
as (C9H
as (C9H
(N4H) (86) +
(C3H) (59) + d(N4H) (32)
3
3
3
3
) (97)
) (56) +
) (82)
) (93)
2912 w
2944 w
2992 m
3003 m
3013 m
3060 w
3127 s
3
mas (C9H ) (27) + d (C6C8H) (12)
m
m
(C2H)] (80) + R1[
(C1H)] (89)
m (C1H)] (15)
3241 m
3385 m
s
(HO5H) (82)
as (HO5H) (97)
Nomenclature:
s
= torsion; sc = scissoring; d = bending; dout = out of plane bending;
m
= stretching;
m
as = asymmetric stretching;
m
s
= symmetric stretching. vs = very strong;
s = strong; m = medium; w = weak; vw = very weak.
a
Only PED values greater that 10% are given.
À1
À1
Fig. 4. Selected representations of atomic vibrations corresponding to the calculated wavenumbers of C
9
H
10
4
N O
ÁH
4 2
O: (a)
x
cal = 220 cm and (b)
x
cal = 935 cm
.
groups were clearly observed at the usual wavenumbers such as:
stretching vibrations of C–H. Stretching vibrations related to C–H
of the R1 ring are observed at 3060 and 3130 cm ; obviously,
À1
À1
À1
torsion of CH
3
in
x
cal = 258 cm and
x
3
cal = 259 cm , rocking of
À1
À1
CH
3
in
x
cal = 1024 cm , wagging of CH
in
in
x
cal = 1420 cm and
no stretching associated to R2 ring are observed in the region of
À1
À1
À1
x
cal = 1435 cm , and scissoring of CH
3
x
cal = 1491 cm . The
3000 cm , because in such a ring the carbon atoms are not bonded
À1
two very intense bands observed above 1700 cm are assigned
as vibrations of R2 ring, both stretching of C7O4 and bending of
C7C4C5;O2O3C6 group.
to any hydrogen atom. The FT-IR spectrum from the crystal
À1
showed two bands above this region, namely at 3241 cm
À1
À1
À1
(x
cal = 3721 cm ) and 3385 cm
(xcal = 3872 cm ), correspond-
For organic crystals, bands resulting from C–H, CH
2
, CH
3
, and N–
ing to the symmetric stretching and asymmetric stretching of
water, respectively. This corroborates the fact that the crystal un-
der study contains water. Finally, it is important to point out that
in the Table 2 there is no assignment to external modes. In fact,
H stretching vibrations are observed in the region between
À1
À1
2
800 cm and 3200 cm . In particular, the band appearing in
À1
the Raman spectrum close to 3000 cm is assigned as an almost
pure band, i.e., as the stretching vibration of N4-H unit, while the
the calculation was performed in a isolated molecule C
ÁH O what means that it cannot furnish vibrations related to lattice
2
9 10 4 4-
H N O
À1
bands observed between 2749 and 2886 cm
are assigned as

1
76
G.M.M. Sampaio et al. / Journal of Molecular Structure 1038 (2013) 170–176
modes. However, it is well known that such a kind of modes must
be found up to 200 cm and, consequently, in this region it is ex-
pect to be found also, the external modes.
[3] D.H. Jones, R. Slack, S. Squires, K.R.H. Wooldridge, J. Med. Chem. 8 (1965) 676–
680.
À1
[
[
4] J.K. Sughen, T. Yoloye, Pharm. Acta Helv. 58 (1978) 64–68.
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In order to illustrate the assignment, atomic displacement vec-
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1
[
7] S. Massa, R. Disanto, A. Retico, M. Artico, N. Simonetti, G. Fabrizi, D. Lamba, Eur.
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molecular structure of C
Fig. 4a it is shown the representation of the atomic vibrations giv-
ing rising to the band observed at ꢀ220 cm , which corresponds
9
H
10
N
4
O
4
ÁH
2
O are shown in Fig. 4. In
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[
3
mainly to the torsional vibration of the two CH groups bonded
464850, 1965. Chem. Abstract 1,147,759, 1966.
to the R2 ring. On the other hand, in Fig. 4b it is shown the repre-
sentation of the atomic vibrations giving rising to the band ob-
served at ꢀ930 cm , which corresponds to vibrations of R1 ring.
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5
. Conclusions
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Pople, Gaussian 03, Revision B.02, Gaussian, Inc., Pittsburgh, PA, 2003.
A study on vibrational properties with an exhaustive frequency
assignment of 2,2-dimethyl-5-(4H-1,2,4-triazol-4-ylaminomethyl-
ene)-1,3-dioxane-4,6-dione monohydrate, O, was
ÁH
C
9
H
10
N
4
O
4
2
performed using the FT-IR and FT-Raman data as well as DFT cal-
culations. The correlation between calculated and experimental
values was very good, and for the first time the Potential Energy
Distribution (PED) is being presented for this synthetic substance.
Due to the size of the molecule, and the numerous superposition of
vibrational modes, bands assignment would have turned impossi-
ble without help from the theoretical model, making a clear state-
ment that theory and experiment must go together.
[15] C.T. Lee, W.T. Yang, R.G. Parr, Phys. Rev. B 37 (1988) 785–789.
[
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[
[
17] A.D. Becke, J. Chem. Phys. 98 (1993) 5648–5652.
18] J.M.L. Martin, C. Van Alsenoy, GAR2PED,
A Computer Program for PED
Acknowledgments
Calculations, University of Antwerp, Belgium, 2007.
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[
[
[
We thank CENAPAD-SP for the use of the GAUSSIAN 03 software
package and for computational facilities made available through
the Project ‘‘proj373’’. Financial support from FUNCAP and CNPq
is also acknowledged.
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Appendix A. Supplementary material
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