5-Benzyl-4-[3-(1H-imidazol-1-yl)propyl]- 2H-1,2,4-triazol-3(4H)-ones: Synthesis, spectroscopic characterization, crystal structure and a comparison of theoretical and experimental IR results by DFT calculations

Article abstract of DOI:10.1016/j.molstruc.2009.07.045

The synthesis and structural properties of novel compounds, 5-Benzyl- 4-[3-(1H-imidazol-1-yl)propyl]-2H-1,2,4-triazol-3(4H)-ones (3a-c) have been described. These products were obtained by the reaction of ethyl 2-[1-ethoxy-2-(phenyl or substituted phenyl)

Full text of DOI:10.1016/j.molstruc.2009.07.045

Journal of Molecular Structure 936 (2009) 46–55
Contents lists available at ScienceDirect
Journal of Molecular Structure
journal homepage: www.elsevier.com/locate/molstruc
5-Benzyl-4-[3-(1H-imidazol-1-yl)propyl]- 2H-1,2,4-triazol-3(4H)-ones: Synthesis,
spectroscopic characterization, crystal structure and a comparison of theoretical
and experimental IR results by DFT calculations
a
c
a
a
Yasemin Ünver a, , Kemal Sancak , Hasan Tanak , Ismail Deg˘irmenciog˘lu , Esra Düg˘dü ,
_
*
Mustafa Er b, Sßamil Ißsık c
a Department of Chemistry, Faculty of Arts and Sciences, Karadeniz Technical University, 61080 Trabzon, Turkey
b Department of Chemistry, Karabük University, 78200 Karabük, Turkey
c Department of Physics, Ondokuz Mayıs University, Samsun, Turkey
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 16 June 2009
Received in revised form 15 July 2009
Accepted 16 July 2009
Available online 12 August 2009
The synthesis and structural properties of novel compounds, 5-Benzyl- 4-[3-(1H-imidazol-1-yl)propyl]-
2H-1,2,4-triazol-3(4H)-ones (3a–c) have been described. These products were obtained by the reaction of
ethyl 2-[1-ethoxy-2-(phenyl or substituted phenyl)ethylidene]hydrazinecarboxylates (1) and N-(3-ami-
nopropyl)imidazol (2). The structures of compounds 3a–c have been inferred through UV–vis, IR,
1H/13C NMR, mass spectrometry, elemental analyses, and X-ray crystallography. DFT level 6-31G (d,p)
*
calculations provided structural information and IR data that were in good agreement with experimental
Keywords:
1,2,4-Triazoles
Imidazol
results for compound 3a. Additionally, the electronic structure of compound 3a has been studied by DFT
*
level 6-31G (d,p) calculations using the X-ray data.
Ó 2009 Elsevier B.V. All rights reserved.
IR
DFT calculations
UV–vis
X-ray crystallography
1. Introduction
Since the first report on the air and H2O stable ionic liquids in
1992 [14], versatile ionic liquids have been investigated [15–25].
The 1,2,4-triazoles posses important pharmacological proper-
ties such as antifungal and antiviral activities. Examples of such
compounds bearing the 1,2,4-triazole residues are fluconazol [1],
the powerful azole antifungal agent as well as the potent antiviral
N-nucleoside ribavirin [2]. Furthermore, various 1,2,4-triazole
derivatives have been reported as fungicidal [3], insecticidal [4],
antimicrobial compounds [5], and some showed antitumor activity
[6], or are anticonvulsants [7], antidepressants [8], and plant
growth regulator anticoagulants [9]. It was reported that com-
pounds having triazole moieties such as vorozole, anastrozole
and letrozole appear to be very effective aromatase inhibitors,
which are very useful for preventing breast cancer [10–12]. It is
known that 1,2,4-triazol moieties interact strongly with heme iron,
and aromatic substituents on the triazoles are very effective for
interacting with the active site of aromatase [13].
Recently, the interest in triazol and imidazol heterocyclic system
has widened as it is a precursor to a class of compounds called
‘room temperature ionic liquids’ [26]. Ionic liquids have high ion
content, high ionic conductivity, low viscosity, nonvolatility, flame
resistance, and other surprising properties as a polar liquid, and
have therefore been investigated as a novel ion conductive matrix
[16–33], as well as reaction solvent [32] and a ‘green solvent’
[33,34].
Ionic liquids, of which imidazolium salts are most widely used,
have gained initial notice of synthetic chemists as environmentally
friendly organic solvents, and continue to hold their attention as
reaction catalysts or promoters [35]. Additionally, They have the
ability to dissolve an enormous range of inorganic, organic, and
polymeric materials at very high concentrations, are noncorrosive,
and have low viscosities and no significant vapor pressures [36,37].
In view of these facts, the aim of the present study is to synthe-
size the triazole-3 one compounds containing imidazol which are
fundamental compounds in the preparation of ionic liquids and
used as a antimicrobial substance.
* Corresponding author. Tel.: +90 462 377 24 85; fax: +90 462 325 31 95.
E-mail address: yasemincan@ktu.edu.tr (Y. Ünver).
0022-2860/$ - see front matter Ó 2009 Elsevier B.V. All rights reserved.
doi:10.1016/j.molstruc.2009.07.045

Y. Ünver et al. / Journal of Molecular Structure 936 (2009) 46–55
47
cooled to r.t. and a solid formed. The crude product was recrystal-
lized using acetone/petroleum ether (1:2) to afford the desired
compound.
2. Experimental
2.1. Physical measurements
1H NMR and 13C NMR spectra were recorded on a Varian XL-200
NMR spectrophotometer in (D6) DMSO. IR spectra were recorded
on a Perkin–Elmer Spectrum one FT-IR spectrometer (resolution 4)
in KBr pellets. The MS spectra were measured with an Micromass
Quattro LC/ULTIMA LC-MS/MS spectrometer with EtOH as solvent.
The experiment was performed in the positive ion mode. Elemen-
tal analyses were performed on a Hewlett–Packard 185 CHN
analyzer. UV/vis spectra were recorded by means of a Unicam
UV2–100 spectrophotometer. M.p. were measured on an electro-
thermal apparatus and are uncorrected. The molecular data were
2.3.1. 5-Benzyl-4-[3-(1H-imidazol-1-yl)propyl]-2H-1,2,4-triazol-
3(4H)-one (3a)
Yield: 221 mg (72%). Colorless crystals. M.p. 161°–162°.
Anal. calc. for C15H17N5O: C, 63.59; H, 6.06; N, 24.72. Found: C,
63.62; H, 6.05; N, 24.73.
IR (KBr,cmÀ1): 1462 (C@N); 1720 (C@O).
1H NMR (200 MHz, DMSOd6): 1.60–1.68 (m, 2H, HAC(12)); 3.39
(t, 4H, J = 3.6, HAC(7) + HAC(13)); 3.87 (t, 2H, J = 3.4, HAC(11));
6.98 (s, 1H, HAC(14)); 7.10 (s, 1H, HAC(15)); 7.23 (s, 2H,
HAC(2)) + HAC(6)); 7.28 (s, 2H, HAC(3) + HAC(5)); 7.32 (s, 1H,
HAC(4)); 7.58 (s, 1H, HAC(16)); 11.59 (s,1H, HAC(9)).
13C NMR (200 MHz, DMSOd6): 29.94 (C(12); 32.81 (C(7)); 38.72
(C(13)); 44.09 (C(11)); 118.61 (C(14)); 129.71 (C(15));
137.06(C(16)); 127.75 (C(2) + (C(6)); 128.41 (C(3) + (C(5)); 129.23
(C(4)), 134.27 (C(1)); 146.47 (C(8)); 156.02 (C(10)).
MS(ESI-m/z): 283.99 [M]+.
collected on an Stoe IPDS II [38] diffractometer using the Mo K
a
radiation at room temperature. For the compounds 3a–c data
collection: X-AREA [38]; cell refinement: X-AREA; data reduction:
X-RED32 [38]; program used to solve structure: SHELXS97 [39];
program used to refine structure: SHELXL97 [39]; molecular fig-
ures: ORTEP III [40]; publication software: WinGX [41] and PARST
[42]. The structures were solved by direct methods with SHELXS-
97 and refined by full-matrix least-squares procedures on F2, using
the program SHELXL-97 computer program belonging to the
WinGX software package.
2.3.2. 4-(3-(1H-imidazol-1-yl)propyl)-5-(3,4-dimethoxybenzyl)-2H-
1,2,4-triazol-3(4H)-one (3b)
Yield: 167 mg (73%). Colorless crystals. M.p. 167–168 °C Anal.
calc. for C17H21N5O3: C, 59.46; H, 6.16; N, 20.41. Found: C, 59.43;
H, 6.15; N, 20.45.
2.2. Materials
IR (KBr, cmÀ1): 1580 (C@N); 1714 (C@O).
The compound (1) was prepared as described by Ikizler and
Sancak [43]. All reactions were carried out under an atmosphere
of dry, O2-free N2, using standart Schlenk techniques. The used sol-
vents (acetone, and petroleum ether) were either of analytical
grade or bulk solvents distilled before use.
1H NMR (200 MHz, DMSOd6): 1.70–1.84 (m, 2H, HAC(12)); 3.48
(t, 2H, J = 3.6, HAC(13)); 3.76 (s, 2H, HAC(7)); 3.87 (t, 8H, J = 6.7,
HAC(11) + HAC(17)); 6.64–6.66 (m, 2H, HAC(5) + HAC(6)); 6.77–
6.83 (m, 2H, HAC(2) + HAC(14)); 7.09 (s, 1H, HAC(15)); 7.47 (s,
1H, HAC(16)); 11.56 (s, 1H, HAC(9)).
2.3. Preparation of compounds (3a-c)
13C NMR (200 MHz, DMSOd6): 29.20 (C(12); 39.46 (C(13));
42.00 (C(7)); 49.27 (C(11)); 55.22 (C(17)); 120.64 (C(14)); 128.19
(C(15)); 136.72 (C(16)); 111.69 (C(2)); 112.22 (C(5)); 120.40
(C(6)); 130.14 (C(1)); 146.44 (C(4)); 147.39 (C(3)); 145.86 (C(8));
156.90 (C(10)).
Ethyl 2-[1-ethoxy-2-(phenyl or substituted phenyl)ethyli-
dene]hydrazine carboxylates (1) (10 mmol) together with N-(3-
aminopropyl)imidazole (2) (1.25 g, 10 mmol) were heated without
solvent in a sealed tube for 2 h at 160 °C. Then, the mixture was
MS(ESI-m/z): 344.20 [M]+.
2
3
7
1
4
8
C
6
NH2
N
5
9
X
O
C
N
NH
10
O
X
N
N
H
NH
11
13
O
NH
C
N
OCH2CH3
+
X
12
N
2
N
OCH2CH3
N
N
14
15
16
N
1
N
3(a-c)
3
a
X
H
17
b
c
3,4-MeO
4-NO2
Scheme 1. Synthetic route to target compounds 3(a–c).

48
Y. Ünver et al. / Journal of Molecular Structure 936 (2009) 46–55
2.3.3. 4-(3-(1H-imidazol-1-yl)propyl)-5-(4-nitrobenzyl)-2H-1,2,4-
triazol-3(4H)-one (3c).
3. Results and discussion
Yield: 156 mg (69%). Colorless crystals. M.p. 169–170 °C.
Anal. calc. for C15H16N6O3: C, 54.87; H, 4.91; N, 25.60. Found: C,
54.86; H, 4.89; N, 25.64.
The synthesis of 5-Benzyl-4-[3-(1H-imidazol-1-yl)propyl]-2H-
1,2,4-triazol-3(4H)-ones (3) was obtained by the reaction of com-
pounds (1) and compound (2) (Scheme 1). Analytical and spectro-
scopic data of the products 3a-c confirmed the success of the
cyclization reaction.
The IR data indicated the formation of compounds 3a–c by the
disappearance of COCH2 (esteric) band of (1) at 1247 cmÀ1, and the
new band at 1697–1714 cmÀ1 belonging to the triazole C@O. In the
IR spectrum of compound 3c, the NO2 group was recorded at 1355
and 1520 cmÀ1. The EI–MS of compounds 3a–c confirmed the pro-
posed structures with a molecular ion peak at m/z = 283.99, 344.20,
and 329.10, respectively.
IR (KBr, cmÀ1): 1584 (C@N); 1697 (C@O); 1355,1520 (NO2).
1H NMR (200 MHz, DMSOd6): 1.85–1.92 (m, 2H, HAC(12)); 3.33
(s, 2H, HAC(7)); 3.48 (t, 2H, J = 3.6, HAC(13)); 3.90 (t, 2H, J = 3.4,
HAC(11)); 6.94 (s, 1H, HAC(14)); 7.06 (s, 1H, HAC(15)); 7.46 (d, A–
A’, 2H, J = 8.8, HAC(2) + HAC(6)); 7.60 (s, 1H, HAC(16)); 8.15 (d, B–
B’, 2H, J = 8.8, HAC(3) + HAC(5)) ; 11.60 (s, 1H, HAC(9)).
13C NMR (200 MHz, DMSOd6): 30.01 (C(12); 38.61 (C(13));
42.16 (C(7)); 46.25 (C(11)); 119.76 (C(14));129.73 (C(15));
137.35 (C(16)); 123.80 (C(2) + (C(6)); 129.80 (C(3) + (C(5));
143.78 (C(1)); 144.90 (C(4)); 144.87 (C(8)); 155.89 (C(10)).
MS(ESI-m/z): 329.10 [M]+.
In the 1H NMR spectra, the existence of 3a–c was revealed by
the disappearance of form of the ester CH2O groups (4.18–
4.24 ppm) in the precursor (1) after the cyclization and the appear-
ance of a new peak at 11.56–11.60 ppm integrating for one H-atom
(exchangeable with D2O) belonging to HAN(10) [44].
The H2C(12) groups of the propyl residue attached to the triazol
and imidazol rings resonate as a multiplet between 1.60–1.92 ppm,
while H2C(13), linked to the imidazol ring, was recorded at 3.39–
3.48 ppm as a triplet, and HAC(11) linked to the triazol ring was
observed at 3.87–3.90 ppm as triplet.
Table 1
Observed and calculated frequencies (cmÀ1), calculated IR intensities (km/mol), and
probable assignment of normal modes for compound 3a.
Observed
Calculated/6–
31G (d,p)
Intensities Assignment
*
3417(m)
3080(ms)
3014(ms)
2996(ms)
2810(ms)
1720(vs)
1636(m)
1580(ms)
1522(m)
1510(m)
1462(ms)
3501
3097
3061
2974
2922
1713
1612
1568
1522
1510
1454
21.37
44
ts(NH)
tas(CH)
ts(CH)
tas(CH)
ts(CH)
tC@O
Coupling constants
J between the imidazol HAC(14) and
40.88
40.77
42.84
153.19
50.14
38.01
93.56
31.98
53.98
HAC(15) were often very small or not observable in DMSO but
sometimes are visible in D2O/CDCl3 [45]. In (D6) DMSO, HAC(15)
and HAC(14) of the imidazol ring of 3a–c resonate as two singlets
at 6.94–6.98 and 7.06–7.10 ppm, respectively. A singlet at 7.47–
7.60 ppm was observed for HAC(16).
More detailed information about the structure of compounds
3a–c was provided by the 13C NMR spectra. The CH2 groups C(7),
C(11), C(12) and C(13) with aliphatic character showed resonances
at 32.81–42.16, 44.09–46.25, 29.20–30.01, and 38.46–38.71 ppm,
respectively. The signals for the triazole C(8) and the C@O group
C(10) are found at 144.87–146.47 and 155.89–156.02 ppm, respec-
tively. The other aromatic C-atoms bearing H-atoms (C(2), C(3),
C(4), C(5), C(6), C(14), C(15), C (16)) are observed at 111.69–
123.80, 129.80–147.39, 129.23–146.44, 112.22–144.90, 120.40–
127.75, 118.61–119.76, 128.19–129.73, 136.72–137.35 ppm,
respectively. Finally, C(1) absorbs at 130.14–143.78 ppm.
tC@C
tas(ring)
ts(ring) + dNH
ds(CHimidazole/triazole) + ds(CH2)
rCHimidazole + rCH2 + dC@Nimidazole/
C-imidazole
1440(m)
1431(m)
1420(m)
1394(mw) 1398
1373(w) 1372
1437
1430
1416
35.03
34.98
12.21
27.11
21.91
25.39
9.66
dCHimidazole/CHbenzene + rCH2
ds(CH2)
ds(CH2)
rring + rCH2
rring + rCH2 + dNH
dCN + rring + rCH2
rCHimidazole/triazole + dC-
Nimidazole + ds(CH2)
1343(mw) 1339
1325(mw) 1312
1285(mw) 1283
92.12
rCHimidazole/triazole + ds(CH2)
dNH + dNHCO
+
1255(m)
1230(ms)
1215(mw) 1212
1183(mw) 1190
1145(w)
1108(m)
1267
1231
32.56
40.97
23
3.16
4.09
31.05
ds(ring) + ds(CH2)
ds(ring) + ds(CH@Nimidazole)
ds(ring)
ds(CHimidazole/triazole) + ds(CH2)
ds(ring) + dNH
ds(CHimidazole/triazole) + ds(CH2)
rring
4. Method of calculations
1137
1111
+
+
4.1. Comparison of the theoretical and experimental Infrared spectra of
compound (3a)
1079(ms)
1059(mw) 1069
1040(mw) 1045
1027(w)
998(m)
919(m)
876(w)
1078
41
rring + rCHimidazole/triazole
rCHimidazole/triazole
ds(ring) + ds(CH2)
cring
17.74
19.99
5.91
31.92
4.26
6.22
In order to construct of ligand molecule, the geometrical param-
eters of ligand 3a were taken from X-ray structure data. The molec-
ular structure of ligand in the ground state was optimized by
density functional using Becke’s three-parameter hybrid method
(B3) with the Lee, Yang and Parr correlation functional methods
1019
990
919
889
cring
rCHimidazole/triazole + rCH2
ds(CHimidazole/triazole) + ds(CH2)
cring
*
850(mw)
829(ms)
750(ms)
728(ms)
847
823
758
729
33
86.94
40
c
ring + ds(CHimidazole)
ds(CH2) C@O + dNH
dring-mono
(LYP) with the Standard 6-31G (d,p) basis set [46,47]. The opti-
+ t
subs.
mized structural parameters were used in the vibrational frequency
calculations at DFT level to characterize all stationary points as
+
cCHimidazole
22.43
ds(CH2)
+
cring-mono
+
subs.
*
minima. 6-31G (d,p) basis set was used for all elements. All calcu-
tC@O + dNH
662(m)
630(mw)
605(mw)
558(w)
545(w)
482(w)
461(w)
667
632
607
560
520
472
461
7.71
5.44
1.11
0.65
12.92
1.25
3.21
cring + cCHimidazole/triazole + dNH
lations were performed with the Gaussian 03W program package
[48]. In calculations, tight converge criteria was used. By allowing
that all the parameters could relax, all the calculations converged
to optimized geometries, which corresponded to true energy min-
ima. The frequency values computed at this level contain known
systematic errors [50]. Therefore, we have used the scaling factor
value of 0.9614 for B3LYP [51]. The vibrational assignments inferred
in Table 1, via the Gaussview program, have been severally checked
and than combined. By combining the results of the Gaussview
c
c
c
c
c
c
CHimidazole/triazole + ds(CH2)
CHimidazole/triazole + ds(CH2) + dNH
ring + ds(CH2) + dNH
ring + ds(CH2) + dNH
ring + ds(CH2)
ring + ds(CH2)
Vibrational modes:
, out-of-plane deformation. Superscript: s, symmetric; as, asymmetric; ring, ben-
zene; w, weak; m, medium; ms, medium strong; mw, medium weak.
t, stretching; d, in-plane deformation; ds, scissoring; r, rocking;
c

Y. Ünver et al. / Journal of Molecular Structure 936 (2009) 46–55
49
tion structure of ligand molecule. For comparison, we present the
main geometric parameters of 3a, obtained both by X-ray diffrac-
*
tion and by calculation at the DFT/6-31G (d,p)-B3LYP level in Table
1. The correlation coefficients of the experimental and theoretical
geometric parameters are calculated to be 0.9614, 0.9545, and
0.9986 for the bond lengths, bond angles, and torsional angles,
respectively. As shown in Table 1, the theoretical values are in good
agreement with the experimental measurements [49,52–54].
4.3. Vibrational spectra
Fig. 1. Calculated molecular structure of 5-Benzyl- 4-[3-(1H-imidazol-1-yl)propyl]-
2H-1,2,4-triazol-3(4H)-one (3a) with atomic numbering.
4.3.1. NH and CH stretching modes
Most organic compounds have CH bonds; a useful rule is that
absorption in the 2850–3000 cmÀ1 is due to sp3–CH stretching
whereas absorption above 3000 cmÀ1 is from sp2 CH stretching.
Also the assignments of the CH2 stretching bands are always
ambiguous since they are coupled with the overtone and combina-
tion band of CH2 bending at around 1450 cmÀ1. In this work, a
major harmony of theoretical values with that of experimental
evaluations was found in the symmetric and asymmetric stretch-
ing vibrations of aromatic CH and CH2 moiety. Four bands in the
region 3100–2810 cmÀ1 were observed in the spectrum. These
assignments are also supported by Silverstein and other [49,55].
The first two bands are depolarized and the latter two bands are
strong and polarized in the spectrum, therefore, we assigned these
bands to the out-of-plane and in-plane asymmetric and symmetric
ACH2 stretching modes, respectively. In addition, in the heterocy-
program with symmetry considerations, vibrational frequency
assignments were made with accuracy. There is always some ambi-
guity in defining internal coordination. However, the described
coordinate generates the studied set and matches quite well with
the motions observed using the Gaussview program. On the basis
of the optimized ground state structure, the spectroscopic proper-
ties and UV–vis absorption calculations in vacuum have been car-
ried out by using the time-dependent density functional theory
(TD-DFT) at B3LYP level, providing an accurate description of UV–
vis transitions of ligand system.
4.2. Molecular geometry
The calculated vibrational spectrum has no imaginary fre-
quency, which indicates that the optimized geometry is located
at the minimum point on the potential energy surface. The calcu-
lations were performed at the point group C(1). The optimized
molecular structure turns out to be very close to the X-ray diffrac-
clic compounds,
3000 cmÀ1. The IR band appearing at 3417 cmÀ1 is assigned to
the NAH stretching mode of vibrations. This vibration mode
calculated at 3501 cmÀ1 for DFT method. The difference between
tNAH vibration occurs in the region 3500–
t
Fig. 2. Frontier orbitals for 3a.

50
Y. Ünver et al. / Journal of Molecular Structure 936 (2009) 46–55
Table 2
Experimental k (nm), selected/calculated TD-DFT singlet energies, MO transitions, oscillator strengths.
Orbital (transitions)
MO coefficiens
Oscillator
Assignment
kexp (nm)
kcalc (nm)
Bond type
HOMO ? LUMO (88 ? 89)
0.631
0.393
0.439
0.349
0.379
0.397
0.671
0.4607
0.0736
p
p
?
?
p
p
*
*
324
309
324.1
319.5
p
p
p
p
p
p
p
(C@C)/(C@O) ?
(C@C)/(C@O) ?
(C@C)/(C@N) ?
(C@C)/(C@O) ?
(C@C)/(C@N) + nb (N16) ?
(C@C)/(C@N) + nb (O) ? *(C@C)/(C@N)
(C@C)/(C@N) + nb (N16) ? *(C@C)
p
p
p
p
*(C@C)
*(C@C) and
*(C@C)
HOMO ? LUMO + 1 (88 ? 90)
HOMOÀ1 ? LUMO (87 ? 89)
HOMO ? LUMO + 2 (88 ? 92)
HOMOÀ1 ? LUMO + 1 (87 ? 90)
HOMOÀ1 ? LUMO + 2 (87 ? 91)
HOMOÀ1 ? LUMO + 1 (87 ? 90)
0.0872
p
nb ?
?
p*/
295
299.2
*(C@C) and
p
*
p*(C@C) and
p
0.114
p
?
p*/
285
255
287.9
256.1
p
nb ? p*
p
nb ? p*
HOMOÀ1 ? LUMO + 2 (87 ? 91)
0.317
0.0845
?
p* /
p
(C@C)/(C@N) + nb (O) ? p*(C@C)/(C@N)
HOMOÀ1 ? LUMO + 2 (87 ? 91)
HOMO ? LUMO + 2 (88 ? 91)
HOMOÀ1 ? LUMO + 2 (87 ? 91)
0.441
0.576
0.337
0.639
0.091
p
p
?
?
p
*
239
236
243
236.7
p
p
p
(C@C)/(C@N) ?
(C@C)/(C@O) ?
(C@C)/(C@N) ?
p
p
p
*(C@C)/(C@N)
*(C@C) and
*(C@C)/(C@N)
p*
experimental and calculated
t
NAH stretching mode is about
ever, with the help of the animation option of Gauss View 3.0
graphical interface for gaussian programs, the tCN vibrations are
identified and assigned in this study. As a result, the IR bands
appearing at 1462.5, 1343.2, 1325.7 and 1230.5 cmÀ1 are assigned to
the tCN vibrations with combination of the ds/Q(@CHimidazole/triazole)
and ds(ring) for the compound 3a.
84 cmÀ1. This striking discrepancy may come from difference be-
tween solid and gas phase, but the IR spectrum of 3a was taken
in KBr pellets while the theoretical calculation of molecule was
performed in gas phase.
4.3.2. 1700–1000 cmÀ1. region
4.3.3. 1000–400 cmÀ1. region
In this region, the strong stretching vibration of the carbonyl
bond contributes to the observed band at 1720 cmÀ1, correspond-
ing to the frequency predicted to be at 1713 cmÀ1. The tC@C
stretching vibration was calculated to lie at 1636 cmÀ1, close to
the typical value. The environment atom next to the double bond
does not affect the bond strength appreciably.
The medium bands at 998.5, 919.6, 876.8, 850.7, 630.9, 482 and
461 cmÀ1 are assigned to the imidazole and triazole ring deforma-
tion (in-plane and out-of-plane) vibrations comparing with the
predicted frequencies at 990.9, 919.96, 889.72, 847.15, 632.06,
472.66 and 461.05 cmÀ1, respectively. The additional ring defor-
mation vibrations with ds(CH2), dC@O and dNH are calculated to be
at 829.3, 558.3 and 545 cmÀ1 with medium and weak intensities.
Two of the ring torsion modes are predicted to be at 758.2 and
729.49 cmÀ1, and were observed at 750 and 728.5 cmÀ1 in the
experimental spectrum. As could not be seen any deformation
vibrations below 400 cmÀ1 in the experimental spectrum, calcu-
lated deformation vibrations below 400 cmÀ1 were neglected.
The calculated intensities tC@C stretching and ds(ring/@CHimidaz-
in-plane bending vibrations are equal while the
ole/@CHtriazole/ACH2)
typical intensities in the spectral correlation tables are weak and
strong, respectively [49]. The bands due to the ring(benzene) and
CHimidazole/triazole stretching are found in the experimental solid IR
spectrum at 1636–1522 cmÀ1 and also the bands at 1510.7–
1040.4 cmÀ1 are assigned to the in-plane and out-of-plane ring,
methylene and CHimidazole/triazole bending vibrations. The deforma-
tion vibrations of ACH2 group (scissoring, wagging, twisting and
rocking) contribute to several vibration modes in low frequency re-
gion. As seen from Table 1, the bands at 1462.5, 1440.7, 1420.1,
1343.2, 1285.7, 1183.8 cmÀ1 in the FT-IR spectrum corresponds
to all deformation ACH2 modes, respectively. The scissoring, wag-
ging, twisting and rocking vibrational modes are distributed in a
4.4. Theoretical aspects of UV–vis spectrum of compound 3a
The Experimental UV–vis spectrum of 3a was measured in chlo-
roform solution, and it was found that the absorption bands max-
imized at 324, 309, 295, 285, 255, 239 and 236 nm. In order to
wide range [49,56]. The identification of tCN vibrations is a difficult
task, since the mixing of vibrations is possible in this region. How-
Table 3
Crystal and experimental data for compounds 3a–c.
3a
3b
3c
Formula: C15H17N5O
Formula weight:
283.34
Formula: C17H21N5O3
Formula weight: 343.39 Formula weight: 328.34
Formula: C15H16N6O3
Crystal system:
orthorhombic
Space group: Pna21
Z = 4
Crystal system:
monoclinic
Space group: P21/c
Z = 4
Crystal system:
monoclinic
Space group: P21/c
Z = 4
a = 10.9331(5) Å
b = 14.9317(10) Å
c = 8.9848(6) Å
a = 16.4386(12)Å
b = 6.3326(3) (10)Å
c = 17.3148(12)Å
b = 105.289(6ꢀ), and
V = 1738.66(19)Å3
No. of reflections
used = 9748
a = 9.0096(5) Å
b = 6.6083(2) Å
c = 26.8310(15)Å
b = 102.594(4ꢀ), and
V = 1559.03(13) Å3
No.of reflections
used = 9183
a
= b =
c = 90ꢀ, and
V = 1466.77(15) Å3
No. of reflections
used = 9748
2hmax = 60° Mo K
R = 0.050
a
2hmax = 60° Mo K
R = 0.050
a
2hmax = 60° Mo K
R = 0.053
a
(
(
(
D
D
D
/
/
/
r
)
max = 0.000
(
(
(
D
D
D
/
/
/
r
)
max = 0.000
(
(
(
D
D
D
/
/
/
r)max = 0.000
q)
max = 0.346 eÅÀ3
q
q
)
)
max = 0.346 eÅÀ3
q)
max = 0.143 eÅÀ3
q)
min = À0.297 eÅÀ3
min = À0.297 eÅÀ3
q)
min = À0.149 eÅÀ3
F(0 0 0) = 600
l
F(0 0 0)= 728
l
F(0 0 0)= 688
= 0.086 mmÀ1
= 0.093 mmÀ1
l
= 0.102 mmÀ1
Fig. 3. Ortep III diagram of 3a.

Y. Ünver et al. / Journal of Molecular Structure 936 (2009) 46–55
51
Fig. 4. Packing diagram of 3a.
understand electronic transitions of 3a, TD-DFT calculations on
electronic absorption spectrum with DFT/6-31G (d,p)-B3LYP level
in vacuum were performed. This method was used to compute
the 156 singlet ? singlet transitions in vacuum (Fig. 1).
The HOMO–LUMO gap is a typical quantity to describe the dy-
namic stability of any molecule. The HOMO–LUMO gap of 3a
(HOMO = À6.311 eV, LUMO = À3.289 eV and The HOMO–LUMO
*
gap is 3.022 eV) is quite a sufficient level for electron transitions.
*
From an inspection to the frontier molecular orbitals of 3a
(Fig. 2) it is seen that the HOMOÀ1 is localized on the substitute
Therefore, the lowest energy absorption is assigned as the
charge transfer [57] (Fig. 3).
p ? p
triazole of mixed
r
- and
*
p-character (C(14) and C(15) atoms), both
p -characters of C- and N-atoms, C(19)/C(20),
of and partially
p
4.5. Crystal structures determination of 3a, 3b and 3c
C(17)/N(18) atoms, and nb on the N (16)/O atoms.
The HOMO is also localized on the substitute triazole of
Crystallographic data of the compound 3a is shown in Table 3.
Molecular system exhibit weak CAH. . .N and CAH. . .O type
mixed
r- and
p
-characters of oxygen O, C(7) and C(13) atoms,
p
*
and partially
p
-characters on the N(9)/C(8), C(11)/N(12) and
N(10)/C(11) atoms. The LUMO is of antibonding character
Table 4
*
Hydrogen-bond geometry (Å, °) of compounds 3a–c.
with
p -symmetry localized on the aromatic rings C(2)/C(3) C(5)/
C(6), C(1) and C(4), and on the C(7), C(8) atoms, respectively. Sim-
3a
D–H. . .A
D–H
H. . .A
D. . .A
D–H. . .A
*
ilarly, LUMO + 1 is of
p orbital of C(1)/C(6), C(3)/C(4), C(2) and C(5)
C1AH1. . . N3
C2AH2. . . O1
C24AH24B. . . O1
DAH. . .A
N3AH22. . .O3
C9AH9B. . .O3
DAH. . .A
N3AH33. . .N6
C2AH2. . .O2A
C7AH7A. . .O3
C10AH10B. . .O3
C15AH15. . .O1A
0.93
0.93
0.97
D–H
0.919(15)
0.980(16)
D–H
0.91(2)
0.93(3)
0.970(18)
0.960(16)
0.959(17)
2.09
2.44
2.49
H. . .A
1.882(16)
2.533(16)
H. . .A
1.98(2)
2.46(3)
2.431(19)
2.525(16)
2.60(2)
2.880(3)
3.246(3)
3.382(4)
D. . .A
2.7976(15)
3.4934(19)
D. . .A
2.8894(17)
3.300(12)
3.390(2)
3.3997(18)
3.486(13)
142.4
144.3
152
atoms, and on the C(7), C(8) atoms, respectively. LUMO + 2 is
*
mostly of
p orbital combination of N(18)/C(19) bond, N(16),
3b
3c
D–H. . .A
174.7(13)
166.3(12)
D–H. . .A
172.8(17)
150(2)
170.3(14)
151.6(12)
154.4(15)
C(17) and C(20) atoms, and on C(14) and C(15) atoms.
Considering that the spectrum of 3a exhibits intense absorption
bands in the about 324–236 nm range some additional intraligand
transitions are expected at higher energies in the calculation. The
assignment of calculated transitions to the experimental bands is
based on the excitation energy and oscillator strength of the calcu-
lated transitions. The results are shown in Fig. 2 and Table 2, where
selected transitions, with significant oscillator strength, are listed.

52
Y. Ünver et al. / Journal of Molecular Structure 936 (2009) 46–55
Fig. 5. Ortep III diagram of 3b.
Fig. 7. Ortep III diagram of 3c.
Fig. 6. Packing diagram of 3b along the b axes.

Y. Ünver et al. / Journal of Molecular Structure 936 (2009) 46–55
53
intermolecular interactions, namely C1AH1. . .N3, C2AH2. . .O1 and
C24AH24B. . .O1, resulting in an intricate three-dimensional net-
work. The adjacent O1 atom, attached to the triazole ring, at (x,
y, z) acts as a hydrogen bond acceptor to atom C1 at (x + 1, y, z)
and C2 at (x + 1/2, Ày + 3/2, z) forming rings with graph set R21
[58] shown in Fig. 4. There is also stacking interaction between
C13-H13B. . .Cg(2), where Cg(2) is plane N4/C2/C1/N5/C4, the dis-
tance H. . .Cg is 2.84 Å and the angle XAH. . .Cg is 163ꢀ, with the
symmetry code (1Àx, 1Ày, 1/2 + z), the details of the H-bond is
shown in Table 4 (Fig. 5).Crystallographic data of the compound
3b is shown in Table 3. The compound 3b is not planar like as
3a. The dihedral angle between the triazole ring (C10/C11/N1/
N2/N3) and the phenyl ring (C1/C2/C3/C4/C5/C6) is 89.33(5ꢀ) show-
ing that these systems are perfect perpendicular to each other.
Although the title compound has no classical hydrogen bond, it
does exhibit weak NAH. . .O and CAH. . .O type hydrogen bonds
are found in crystal packing, namely N3AH22. . .O3 (symmetry
code: Àx,Ày + 1, Àz + 1) and C9AH9. . .O3 (symmetry code: x,
yÀ1, z) where adjacent atom O3 accepts hydrogen bonds from
CAH donors (Table 4, Fig. 6). There is also
p
–
p
stacking interaction
in the title compound, 3b. The perpendicular distance between the
Cg1 ring in a neighboring molecule is 3.49 Å at (Àx, 1Ày, Àz) [Cg1 is
the ring centroid of the N1AC11 ring]. Both compounds 3a and 3b
exhibit weak, but slightly different, intermolecular attractions. In
3a C1AH1. . .N3, C2AH2. . .O1, C24AH24B. . .O1 and CAH. . .
actions, while in 3b, the interactions are N3AH22. . .O3,
C9AH9. . .O3 and
p inter-
p–p.
Crystallographic data of the compound 3c is shown in Table 3.
The high values of the displacement parameters of the N and O
atoms of the nitro group attached the phenyl indicating disorder
of this group. Following sequence of the refinement and difference
Fourier syntheses, disordered atoms, N1, O1 and O2 was recog-
nized in 52(2):48(2) ratio in the nitro group. Their atomic displace-
ment parameters are slightly larger than those of the other atoms.
In the compound 3c, the ring systems are almost planar
whereas the whole molecule is not planar (Fig. 7). The dihedral an-
gle between the phenyl and triazole ring system is 89.94(5ꢀ), that
shows these systems are perpendicular to the each other. The
Fig. 8. Packing diagram of 3c along the b axes.

54
Y. Ünver et al. / Journal of Molecular Structure 936 (2009) 46–55
[17] (a) D.R. MacFarlane, P. Meakin, J. Sun, N. Amini, M. Forsyth, J. Phys. Chem. B
103 (1999) 4164;
molecular geometry of the triazole ring is in agreement values with
the structures 3-[(5-Methyl-2-oxo-1,3-benzoxazol-3-yl)methyl]-
4-phenyl-1H-1,2,4-triazole-5(4H)-thione [59] and 4-Allyl-3-[(5-
methyl-2-oxo-1,3-benzoxazol-3-yl)methyl]-1H-1,2,4-triazole-
5(4H)-thione [60].
(b) D.R. MacFarlane, J. Huang, M. Forsyth, Nature 402 (1999) 792.
[18] R. Hagiwara, T. Hirashige, T. Tsuda, Y. Ito, J. Fluorine Chem. 99 (1999) 1.
[19] H. Matsumoto, T. Matsuda, Y. Miyazaki, Chem. Lett. (2000) 1430.
[20] (a) H. Matsumoto, M. Yanagida, K. Tanimoto, M. Nomura, Y. Kitagawa, Y.
Miyazaki, Chem. Lett. (2000) 922;
The molecular structure is stabilized by NAH. . .N and CAH. . .O
type intermolecular hydrogen bonds. In the compound 3c, the
adjacent O atom of the triazole ring acts as a hydrogen bond accep-
tor involving an intermolecular interaction with atom C7 and atom
C10, like as the molecules 3a and 3b. Namely, C7-H7A. . .O3 (sym-
metry code: x, yÀ1, z), C10AH10B. . .O3 (symmetry code: Àx + 1,
Ày + 2, Àz + 1). The latter interaction link the molecules into one-
dimensional chain along (1 0 0) (Fig. 8), these interactions are,
N3AH33. . .N6 (symmetry code: xÀ1, y + 1, z), C2AH2. . .O2A (sym-
metry code: Àx + 2, yÀ1/2, Àz + 3/2) and C15AH15. . .O1A (symme-
try code: Àx + 2, y + 1/2, Àz + 3/2). The details of the hydrogen
(b) H. Matsumoto, H. Kageyama, Y. Miyazaki, Chem. Lett. (2001) 182.
[21] H. Ohno, K. Ito, Chem. Lett. (1998) 751.
[22] M. Yoshizawa, H. Ohno, Chem. Lett. (1999) 889.
[23] S.I. Lall, D. Mancheno, S. Castro, V. Behaj, J.I. Cohen, R. Engel, Chem. Commun.
(2000) 2413.
[24] J.H. Davis Jr., K.J. Forrester, T. Merrigan, Tetrahedron Lett. 39 (1998) 55.
[25] A.S. Larsen, J.D. Holbrey, F.S. Tham, C.A. Reed, J. Am. Chem. Soc. 122 (2000)
7264.
[26] For reviews, see: (a) J.S. Wilkes, Green Chem. 4 (2002) 73;
(b) R. Sheldon, Green Chem. 4 (2002) 73;
(c) P. Wasserscheid, W.K. Angew, Chem, Int. Ed. 39 (2000) 3772;
(d) Y. Chauvin, .H. Olivier, Chemtech (1995) 26.
[27] V.R. Koch, C. Nanjundiah, G.B. Appetecchi, B. Scrosati, J. Electrochem. Soc.
(1995) L116.
[28] A.B. McEwen, H.L. Ngo, K. LeCompte, J.L. Goldman, J. Electrochem. Soc. 146
(1999) 1687.
bonds are shown in the Table 4. There is also weak p–p interaction
between the Cg2 ring in a neighboring molecule is 3.97 Å at (2Àx,
[29] A. Noda, M. Watanabe, Electrochim. Acta 45 (2000) 1265.
[30] (a) N. Papageorgiou, Y. Athanassov, M. Armand, P. Bonhoˆ te, H. Pettersson, A.
Azam, M. Gratzel, J. Electrochem. Soc. 143 (1996) 3099;;
(b) H. Matsumoto, T. Matsuda, T. Tsuda, R. Hagiwara, Y. Ito, Y. Miyazaki, Chem.
Lett. (2001) 26.
2Ày, Àz) [Cg2 is the ring centroid of the N5AC15 ring].
5. Conclusions
[31] M. Doyle, S.K. Choi, G. Proulx, J. Electrochem. Soc. 147 (2000) 34.
[32] T. Welton, Chem. Rev. (1999) 2071.
In conclusion, new triazole-3-one derivatives containing an imi-
dazol ring, which are fundamental compounds in the preparation
of ionic liquids and used as a antimicrobial substance, have been
prepared and characterized by combination of X-ray crystallogra-
phy, elemental analysis, 1H- and 13C NMR spectra, mass spectra,
IR and UV–vis spectra, and theoretical methods. In the compound
3a, all the ring systems are completely planar, while the complete
molecule is non-planar. In addition, while oxygen, nitrogen (2, 3
and 5) atoms are lie out of rings, especially aliphatic C(23) atom
is twisted into cavity of molecule. We have, however attempted
to assign the calculated frequencies to the corresponding observed
values based on the concept of group frequencies and intensity
profiles. The compound 3b, C17H21N5O3, is not planar. In the com-
pound 3c, C15H16N6O3, the ring systems are almost planar whereas
the whole molecule is not planar.
[33] (a) J.G. Huddleston, H.D. Willauer, R.P. Swatloski, A.E. Visser, R.D. Rogers,
Chem. Commun. (1998) 1765;
(b) A.E. Visser, R.P. Swatloski, W.M. Reichert, R. Mayton, S. Sheff, A. Wierzbicki,
J.H. Davis Jr., R.D. Rogers, Chem. Commun. (2001) 135.
[34] V.V. Nomboodiri, R.S. Varma, Org. Lett. (2002) 3161.
[35] Recent examples: (a) Y. Gu, F. Shi, Y. Deng, J. Org. Chem. 69 (2004) 391;
(b) F. Shi, H. Xion, Y. Gu, S. Guo, Y. Deng, Chem. Commun. (2003) 1054;
(c) E.J. Kim, S.Y. Ko, C.E. Song, Helv. Chim. Acta 86 (2003) 894;
(d) J.N. Rosa, C.A.M. Afonso, A.G. Santos, Tetrahedron 57 (2001) 4189;
(e) T. Tsuchimoto, T. Maeda, E. Shirakawa, Y. Kawakami, Chem. Commun.
(2000) 1573;
(f) C.E. Song, W.H. Shim, E.J. Roh, S.-G. Lee, J.H. Choi, Chem. Commun. 2 (2001)
1122.
[36] R. Hagiwara, Y.J. Ito, J. Fluorine Chem. 105 (2000) 221.
[37] J.D. Holbrey, K.R. Seddon, J. Chem. Soc., Dalton Trans. (1999) 2133.
[38] Stoe & Cie (2002). X-AREA (Version 1.18) and X-RED32 (Version 1.04). Stoe &
Cie, Darmstadt, Germany.
[39] G.M. Sheldrick, SHELXS97 and SHELXL97, University of Göttingen, Germany,
1997.
[40] Burnett M.N., Johnson C.K. (1996). ORTEPIII. Report ORNL-6895. Oak Ridge
National Laboratory, Tennessee, USA.
[41] L.J. Farrugia, J. Appl. Cryst. 32 (1999) 837.
[42] M. Nardelli, J. Appl. Cryst. 28 (1995) 659.
Acknowledgements
[43] A. Ikizler, K. Sancak, Rov. Roumaine Chim. 43 (1998) 133.
[44] R. Milcent, C. Redeuilh, J. Heterocycl. Chem. 16 (1979) 403.
[45] G. Laus, V. Kahlenberg, D.M. Többens, R.K.R. Jetti, U.J. Griesser, J. Schütz, E.
Kristeva, K. Wurst, H. Schottenberger, Crystal Growth & Desing 6 (2006) 404.
[46] C. Aleman, J. Puiggali, J. Org. Chem. 64 (1999) 351.
[47] M. Er, K. Sancak, I. Deg˘irmenciog˘lu, K. Serbest, J. Mol. Struct. 882 (2008) 35–46.
[48] M.J. Frisch, G.W. Trucks, H.B. Schlegel, G.E. Scuseria, M.A. Robb, J.R. Cheeseman,
J.A. Montgomery Jr., T. Vreven, K.N. Kudin, J.C. Burant, J.M. Millam, S.S. Iyengar,
J. Tomasi, V. Barone, B. Mennucci, M. Cossi, G. Scalmani, N. Rega, G.A.
Petersson, H. Nakatsuji, M. Hada, M. Ehara, K. Toyota, R. Fukuda, J. Hasegawa,
M. Ishida, T. Akajima, Y. Honda, O. Kitao, H. Nakai, M. Klene, X. Li, J.E. Knox, H.P.
Hratchian, J.B. Cross, C. Adamo, J. Jaramillo, R. Gomperts, R.E. Stratmann, O.
Yazyev, A.J. Austin, R. Cammi, C. Pomelli, J.W. Ochterski, P.Y. Ayala, K.
Morokuma, G.A. Voth, P. Salvador, J.J. Dannenberg, V.G. Zakrzewski, S.
Dapprich, A.D. Daniels, M.C. Strain, O. Farkas, D.K. Malick, A.D. Rabuck, K.
Raghavachari, J.B. Foresman, J.V. Ortiz, Q. Cui, A.G. Baboul, S. Clifford, J.
Cioslowski, B.B. Stefanov, G. Liu, A. Liashenko, P. Piskorz, I. Komaromi, R.L.
Martin, D.J. Fox, T. Keith, M.A. Al-Laham, C.Y. Peng, A. Nanayakkara, M.
Challacombe, P.M.W. Gill, B. Johnson, W. Chen, M.W. Wong, C. Gonzalez, J.A.
Pople, GAUSSIAN-03, Revision C.02, Gaussian, Inc., Pittsburgh, PA, (2003).
[49] K. Sancak, M. Er, Y. Ünver, M. Yildirim, I. Degirmencioglu, K. Serbest, Trans.
Met. Chem. 32 (2007) 16.
[50] J.B. Foresman, E. Frisch, Exploring Chemistry with Electronic Structure
Methods: A Guide to Using Gaussian, Gaussian, Pittsburg, PA, 1993.
[51] A.P. Scott, L. Radom, J. Phys. Chem. 100 (41) (1996) 16502.
[52] G.W. Burton, T. Doba, E.J. Gabe, L. Hughes, F.L. Lee, L. Prasad, K.U. Ingold, J. Am.
Chem. Soc. 107 (1985) 7053.
[53] G.W. Burton, Y. Le Page, E.J. Gabe, K.U. Ingold, J. Am. Chem. Soc. 102 (1980)
7791.
[54] G.W. Burton, K.U. Ingold, J. Am. Chem. Soc. 103 (1981) 6472.
[55] M. Silverstein, G. Clayton Basseler, C. Morill, Spectrometric Identification of
Organic Compounds, Wiley, New York, 1981.
This study was supported by Grants from Karadeniz Technical
University (project No.: 2007.111.002.11) and the scientific and
technological research council (TUBITAK project No.: 107T065) of
Turkey.
References
[1] T. Tsukuda, Y. Shiratori, M. Watanabe, H. Ontsuka, K. Hattori, M. Shirai, N.
Shimma, Bioorg. Med. Chem. Lett. 8 (1998) 1819.
_
_
[2] I. Küçükgüzel, Sß.G. Küçükgüzel, S. Rollas, G. Ötük-Sanısß, O. Özdemir, I. Bayrak,
T. Altug˘, J.P. Staples, Il Farmaco 59 (2004) 893.
[3] B. Modzelewska, J. Kalabun, Pharmazie 54 (1999) 503.
[4] B.S. Holla, K.N. Poorjary, B.S. Rao, M.K. Shivananda, Eur. J. Med. Chem. 37
(2002) 511.
[5] E. Palaska, G. Sahin, P. Kelicen, N.T. Durlu, G. Altınok, Il Farmaco 57 (2002) 101.
[6] S. Tehranchian, T. Akbarzadeh, M.R. Fazeli, H. Jamalifar, A. Shafiee, Bioorg. Med.
Chem. Lett. 15 (2005) 1023.
[7] (a) M.I. Husain, M. Amir, J. Indian Chem. Soc. 63 (1986) 317;
(b) M.I. Husain, M. Amir, Chem. Abstr. 106 (1987) 176272h.
[8] S.H.L. Chiu, S.E.W. Huskey, Drug Metabol. Dispos. 26 (1998) 838.
[9] R. Eliott, R.L. Sunley, D.A. Griffin, Chem. Abstr. 107 (1987) 134310n.
[10] P.E. Goss, K. Strasser-Weippl, Best Pract. Res. Clin. End. Met. 18 (2004) 113.
[11] J.R. Santen, Steroids 68 (2003) 559.
[12] M. Clemons, R.E. Colemon, S. Verma, Cancer Treat. Rew. 30 (2004) 325.
[13] S. Chen, Y.C. Kao, C.A. Laughton, J. Steroid Biochem. 61 (1997) 107.
[14] J.S. Wilkes, M.J. Zaworotko, J. Chem. Soc. Chem. Commun. (1992) 965.
[15] J. Fuller, R.T. Carlin, H.C. De Long, D. Haworth, J. Chem. Soc., Chem. Commun.
(1994) 299.
[16] P. Bonhote, A.-P. Dias, M. Armand, N. Papageorgiou, K. Kalyanasundaram, M.
Gratzel, Inorg. Chem. 35 (1996) 1168.
[56] H. Aslan, U. Flörke, N. Külcü, Spectrochim. Acta A 67 (2007) 936.

Y. Ünver et al. / Journal of Molecular Structure 936 (2009) 46–55
[57] A.H. Jubert, M.L. Alegre, R.P. Diez, A.B. Pomilio, V.D. Szewczuk, Spectrochimica
55
[59] Y. Köysal, Sß. Ißsık, U. Salgın, N. Gökhan, Acta Cryst. Section
E
E
63 (2007)
63 (2007)
Acta Part A 66 (2007) 1208.
2462.
[58] J. Bernstein, R.E. Davies, L. Shimoni, N.L. Chang, Angew. Chem. Int. Ed. Engl. 34
(1995) 1555.
[60] Y. Köysal, Sß. Ißsık, U. Salgın, N. Gökhan, Acta Cryst. Section
2463.