An experimental and theoretical approach to molecular structure of 4-benzoyl-5-phenyl-1-p-methoxyphenyl-1H-pyrazole-3-carboxylic acid methanol solvate

Article abstract of DOI:10.1016/j.molstruc.2010.06.007

The title compound, 4-benzoyl-5-phenyl-1-p-methoxyphenyl-1H-pyrazole-3- carboxylic acid (C₂₄H₁₈N₂O₄), was prepared from the reaction of 4-methoxyphenylhydrazine with 4-benzoyl-5-phenyl- 2,3-dihydro-2,3-furandion

Full text of DOI:10.1016/j.molstruc.2010.06.007

Journal of Molecular Structure 980 (2010) 1–6
Contents lists available at ScienceDirect
Journal of Molecular Structure
journal homepage: www.elsevier.com/locate/molstruc
An experimental and theoretical approach to molecular structure
of 4-benzoyl-5-phenyl-1-p-methoxyphenyl-1H-pyrazole-3-carboxylic
acid methanol solvate
a
b
b
Sibel Demir a, , Muharrem Dinçer , Elif Korkusuz , Ismail Yıldırım
_
*
a Department of Physics, Faculty of Arts and Sciences, Ondokuz Mayıs University, 55139 Kurupelit, Samsun, Turkey
b Department of Chemistry, Faculty of Arts and Sciences, Erciyes University, 38039 Kayseri, Turkey
a r t i c l e i n f o
a b s t r a c t
Article history:
The title compound, 4-benzoyl-5-phenyl-1-p-methoxyphenyl-1H-pyrazole-3-carboxylic acid (C24H18N2-
O4), was prepared from the reaction of 4-methoxyphenylhydrazine with 4-benzoyl-5-phenyl-2,3-dihy-
dro-2,3-furandione, in good yield (63%), and characterized by IR, 1H-NMR, 13C-NMR and single-crystal
X-ray diffraction (XRD) and elemental analysis. The compound crystallizes in the monoclinic space group
P 21/c with a = 10.9369 Å, b = 8.6306 Å, c = 23.7823 Å and b = 102.461°. Moreover, the molecular geome-
try from X- ray experiment, the molecular geometry, vibrational frequencies, gauge including atomic
orbital (GIAO) 1H and 13C chemical shift values of the title compound in the ground state have been cal-
culated by using the Hartree–Fock (HF) and density functional methods (B3LYP) with 6-31G(d) basis set.
The results of the optimized molecular structure are exhibited and compared with the experimental
Received 19 March 2010
Received in revised form 7 June 2010
Accepted 8 June 2010
Available online 31 July 2010
Keywords:
X-ray structure determination
Hartree–Fock
Vibrational assignment
Density functional method
1H
_
X-ray diffraction. In addition to, molecular electrostatic potential (MEP) and frontier molecular orbitals
(FMO) were executed by the B3LYP/6-31G(d) and PBEPBE/ 6-31G(d) method, respectively.
13C NMR
Crown Copyright Ó 2010 Published by Elsevier B.V. All rights reserved.
1. Introduction
2. Experimental
Pyrazoles are important compounds that have many derivatives
with a wide range of interesting properties [1–4]. Recyclization
reactions of 4-benzoyl-5-phenyl-2,3-dihydro-2,3-furandione with
various phenylhydrazones and phenylhydrazine lead to pyrazole-
carboxylic acid and pyridazinones [5,6]. In this study, we present
results of a detailed investigation of the synthesis and structure
characterization of 4-benzoyl-5-phenyl-1-p-methoxyphenyl-1H-
pyrazole-3-carboxylic acid using single-crystal X-ray, IR and quan-
tum chemical methods, besides elemental analysis. The title
compound is a novel compound synthesized firstly in our laborato-
ries by us. The nucleophilic addition reaction of 4-methoxyphenyl-
hydrazine with 4-benzoyl-5-phenyl-2,3-dihydro-2,3-furandione
have not been previously studied, and the product (title compound)
is completely original. As part of our ongoing study of the
relationship between the molecular and crystal structures of the
1H-pyrazole-3-carboxylic acid derivatives, a crystal structure deter-
mination of the title compound, has been undertaken and the results
are presented here.
2.1. Physical measurements
Melting points were measured on an Electrothermal 9200 appa-
ratus and are uncorrected. Microanalysis for C and H was per-
formed using a Leco-932 CHNS-O Elemental Analyzer. The IR
spectra of the compound were recorded in the range of 400–
4000 cmÀ1 region with a Shimadzu FT-IR-8400 model and a Jasco
FT-IR-460 Plus model spectrometers. After completion of the reac-
tions, solvents were evaporated with rotary evaporator (Heildolph
4001 G1). Solvents were dried by refluxing with the appropriate
drying agents and distilled before use. All other reagents were pur-
chased from Merck, Fluka, Aldrich and used without further purifi-
cation. The starting material was prepared according to the
literature procedure that described by Ziegler and co-workers [7]
and by Akçamur and co-workers [8].
2.2. Preparation of the title compound
A milliequimolar mixture of 4-benzoyl-5-phenyl-2,3-dihydro-
2,3-furandione (0.278 g, 1 mmol) and 4-methoxyphenylhydrazine
hydrochloride (0.175 g, 1 mmol) were refluxed in benzene for 6 h
by adding 2–3 drops pyridine. The solvent was evaporated, then
* Corresponding author. Tel.: +90 03623121919/5260; fax: +90 03624576081.
E-mail address: sibeld@omu.edu.tr (S. Demir).
0022-2860/$ - see front matter Crown Copyright Ó 2010 Published by Elsevier B.V. All rights reserved.
doi:10.1016/j.molstruc.2010.06.007

2
S. Demir et al. / Journal of Molecular Structure 980 (2010) 1–6
Table 1
the oily residue was treated with diethyl ether and the formed
crude product was recrystallized from methanol. (Scheme 1)
(yield: 0.254 g, 63%; m.p. 232 °C).
Crystallographic data for title compound.
Formula
C24H18N2O4.CH4O
430.45
296
0.71073
Monoclinic
P21/c
10.9360(15)
8.6306(9)
23.782(3)
90
102.461(10)
90
2191.8(5)
4
1.304
904
Formula weight
Temperature (K)
Wavelength (Å)
Crystal system
Space group
a (Å)
2.2.1. Data for the title compound
Anal calcd for C24H18N2O4 (398.41): C, 72.35; H, 4.55; N, 7.03%.
Found: C, 72.13; H, 4.72; N, 6.94%. FT-IR (KBr, m
, cmÀ1): 3433 (b,
OAH, COOH), 3060, 3012 (aromatic CAH), 2941, 2900, 2830 (ali-
phatic CAH), 2000–1700 (overtone or combination bands), 1681
(s, C@O), 1607, 1587, 1556, 1510, 1467, 1441 (phenyl and pyrazole
rings CAC, CAN), 1251 (asym. CAOAC), 984 (sym. CAOAC), 841,
821, 808, 790, 776, 751 (out-off-plane CAH bend), 702, 684 (out-
off-plane rings CAC bend) [9].
b (Å)
c (Å)
a
(o)
b (o)
c
(o)
V (Å3)
Z
Dcalc (g/cm3)
F(000)
2.3. Crystallographic analysis
h, k, l range
À13 6 h 6 13
À9 6 k 6 10
À29 6 l 6 29
12,443
4306
0.069
Data collection was performed on a STOE IPDS II image plate
detector using Mo Ka radiation (k = 0.71073 Å). Intensity data were
Refections collected
Independent refections
Rint
collected in the h range 1.8–26.00° at 296 K. Data collections: Stoe
X-AREA [10]. Cell refinement: Stoe X-AREA [10]. Data reduction:
Stoe X-RED [10]. The structure was solved by direct methods using
SHELXS-97 [11] and anisotropic displacement parameters were ap-
plied to non-hydrogen atoms in a full-matrix least-squares refine-
ment based on F2 using SHELXL-97 [11]. Molecular drawings were
obtained using ORTEP-III [12]. CCDC number is 769839.
Refections observed [I P 2
r
(I)]
2382
0.053
0.126
0.983
Shelxs-97
Full matrix
0.14, À0.34
R [I > 2
r(I)]
Rw [I > 2
r
(I)]
Goodness-of-fit on indicator
Structure determination
Refinement
(Dr)max, (Dr
min) (e/Å3)
3. Computational details
C@N and CAN bond lengths are all shorter than those found in
similar structures [C@N 1.291(2)–1.300(10) Å, CAN 1.482(2)–
1.515(9) Å][23]. Morever, the NAN bond length is shorter than those
found in the above-cited structures [NAN 1.373(2)A1.380(8) Å]
[24]. The dihedral angles between the pyrazol ring with the phenyl
rings (C4–C9), (C17–C22), (C10–C15) 58.5(11), 70.9(12),
55.17(10)°, respectively.
In the crystal lattice, there are two potentially intermolecular
interactions (OAH. . .Y, Y@O,N) [25,26]. The distances and angles
between donor and acceptor are 2.940(3) Å and 164 for O2AH55
. . .N2 and 2.971(3) Å and 115° for O2AH55. . .O2, respectively
[symmetry code: Àx + 1, Ày + 2, Àz + 1]. In the crystal structure,
intermolecular OAH. . .N hydrogen bonds form centrosymmetric
dimers which are linked by further OAH. . .O hydrogen bonds
involving methanol molecules (Fig. 2). There is one CAH. . .Cg
The molecular structures of the title compound in the ground
state (in vacuo) are optimized by Hartree–Fock (HF) and DFT
(B3LYP) [13,14] with 6-31G(d) [15] basis set. For the modelling,
the initial guess of the title compound was first obtained from
the X-ray coordinates. Then vibrational frequencies for optimized
molecular structures have been calculated. The geometry of the ti-
tle compounds, together with that of tetramethylsilane (TMS) is
fully optimized. 1H- and 13C-NMR chemical shifts are calculated
within GIAO approach [16,17] applying B3LYP and HF method
[18] with 6-31G(d) basis set. 1H and 13C isotropic magnetic shield-
ing (IMS) of any X carbon atom, to the average 13C IMS of TMS:
CSx = IMSTMS À IMSx. Molecular geometry is restricted and all the
calculations are performed by using Gauss-View molecular visual-
isation program [19] and Gaussian 03 program package on per-
sonal computer [20]. For the calculations of the MEP [21,22], the
same level of theory B3LYP/6-31G(d), were used.
(p-ring) (edge to face) intermolecular interactions, details of which
are given in Table 2. Hydroxy atom in the methanol at (x,y,z) acts as
hydrogen- bond donor, via atom H55, to ring atom N2 and O2 in
the molecule at (Àx + 1, Ày + 2, Àz + 1), so generating by inversion
a centrosymmetric dimer, centered at (1/2, 1/2, 1/2) and character-
ized by R44(14) motif [27] (Fig. 2).
4. Results and discussion
4.1. Geometrical structure
The structure determinations are given in Table 1.
For the title compound, the displacement ellipsoid plot with the
numbering scheme geometric structure of the title compound are
shown in Fig. 1 and perspective view of the crystal packing in the
unit cell is shown in Fig. 2. All of the bond lengths and bond angles
in phenyl rings are in the normal range. In the pyrazol ring, the
4.2. Theoretical structures
The optimized parameters of the title compound (bond lengths
and angles, and dihedral angles) by HF and B3LYP methods with 6-
31G(d) as the basis set are listed in Table 3 and compared with the
experimental crystal structure for the title compound.
The bands calculated in the measured region 4000–400 cmÀ1
arise from the vibrations of OAH, NAH stretching, and the internal
vibrations, etc. of the title compound. The vibrational bands assign-
ments have been made by using Gauss-View molecular visualiza-
tion program [28]. Frequency calculations at the same levels of
theory revealed no imaginary frequencies, indicating that an opti-
mal geometry at these levels of approximation was found for the
title compound. Vibrationally frequencies calculated at B3LYP/6-
31G(d) and HF/6-31G(d) levels were scaled by 0.9613 and
HO
O
O
O
CH3
O
Ph
OH
Ph
Ph
H2NNH-PhOCH3
N
Ph
N
O
O
PhOCH3
Scheme 1. Synthesis scheme of the title compound.

S. Demir et al. / Journal of Molecular Structure 980 (2010) 1–6
3
Fig. 1. The molecular structure of the title molecule, showing the atom-numering scheme. Displacement ellipsoids are drawn at the 40% probability level and H atoms are
shown as small spheres of arbitrary radii.
Fig. 2. Part of the crystal structure of the title molecule, showing the formation of a chain of centrosymmetric R dimers. For the charity, only H atoms involved in hydrogen
bonding have been included.
0.8929, respectively [29]. Some primary calculated harmonic fre-
quencies are listed in Table 4 and compared with the experimental
data. The descriptions concerning the assignment have also been
indicated in the Table 4. To make comparison with experiment, we
present correlation graphics in Fig. 3 based on the calculations. As
we can seen from correlation graphic in Fig. 3, experimental funda-
mentals are close to agreement with the scaled fundamentals.
Most bonds observed in infrared spectra of the title compound
owned by phenyl and methoxyphenyl groups’ modes, only some of
Table 2
Hydrogen bonding geometry (Å, °) for the title compound.
DAHÁ Á ÁA
DAH
(Å)
HÁ Á ÁA/H. . .Cg
DÁ Á ÁA/D. . .Cg
DAHÁ Á ÁA(Cg)
(°)
(Å)
(Å)
(Å)
O2AH2Á Á ÁO5
0.82
0.82
0.82
0.96
1.77
2.14
2.53
2.94
2.572(3)
2.941(4)
2.971(4)
3.679(6)
166
164
115
134
O5AH55Á Á ÁN2(i)
O5AH55. . .O2(i)
C25AH25A. . .Cg(3)
Note: symmetry code: (i) Àx + 1, Ày + 2, Àz + 1, Cg(3): C10AC15ring.
Fig. 3. Correlation graphics of calculated and experimental frequencies of the title compound.

4
S. Demir et al. / Journal of Molecular Structure 980 (2010) 1–6
Table 3
Table 4
Selected optimized and experimental geometries parameters of the title compound in
ground state.
Comparison of the observed and calculated vibrational spectra of the title compound.
Assignments
Experimental IR with KBr
Calculated (cmÀ1) (6-
31(d))
Parameters
Experimental Calculated
(cmÀ1
)
HF 6-
31G(d)
DFT/B3LYP 6-
31G(d)
DFT/
B3LYP
HF
Bond lengths (Å)
O(2)AC(23)
C(23)AO(3)
C(23)AC(1)
C(1)AN(2)
N(2)AN(1)
N(1)AC(3)
C(3)AC(2)
OAH (methanol) str.
OAH str.
CAH asym-str.
CAH sym. str.
CH3 (methanol) asym.
str.
CH3 asym. str.
CH3(methanol) sym.
str.
CH3 sym. str.
C@O str. + OAH rock.
C@O str.
–
3614
3181
2993
3080
2973
3690
3435
3035
1.315(3)
1.206(2)
1.471(3)
1.340(3)
1.352(2)
1.370(3)
1.377(3)
1.407(3)
1.497(3)
1.477(3)
1.224(3)
1.440(3)
1.368(3)
1.423(3)
1.252(4)
1.308
1.194
1.483
1.300
1.323
1.360
1.370
1.415
1.500
1.496
1.196
1.426
1.345
1.400
1.411
1.333
1.222
1.481
1.332
1.348
1.382
1.392
1.421
1.498
1.494
1.225
1.429
1.362
1.419
1.434
3433
3060
3012
–
3027–3017
3008
2941
–
2964
2916
2930
2871
C(2)AC(1)
C(2)AC(16)
C(16)AC(17)
C(16)AO(4)
N(1)AC(10)
C(13)AO(1)
O(1)AC(24)
O(5)AC(25)
2900
–
1681
1587
1556
1510
1467
–
–
1251
–
–
–
1441
–
–
–
–
–
–
2909
1718
1670
1608
1516
1505
1480
1376
1474
1471
1445
1441
1437
1403
1382
1350
1329
1315
1249
1226
2873
1786
1761
1598
1559
CAC str.
C@C str + C@N str.
CAN str. + CAH rock.
CAH bend.
CH3 (methanol) sci.
CH3 sci.
OAH bend. + OCC str
CH3 (methanol) vag.
CH3 vag.
CAH rock.
NCC str.
OAH rock. + CAC str.
NNC str. + NC str.
OAH (methanol) rock.
C@C str.
1528
1503–1496
1485
Bond angles (°)
1486
1392
1463
1461
1444
1442
1392
1368
1343
1295
1284
1255
N(2)AN(1)AC(3)
N(1)AC(3)AC(2)
C(3)AC(2)AC(1)
C(2)AC(1)AN(2)
N(2)AC(1)AC(23)
N(2)AN(1)AC(10)
C(10)AN(1)AC(3)
C(2)AC(16)AO(4)
C(1)AC(23)AO(2)
C(1)AC(23)AO(3)
C(3)AN(1)AC(10)
C(1)AC(2)AC(16)
112.2(17)
106.7(19)
104.7(19)
111.9(19)
120.8(2)
119.5(17)
128.3(18)
119.7(2)
112.7(19)
122.7(2)
128.3(18)
128.9(2)
112.237
106.132
104.196
111.377
122.193
118.465
129.256
119.803
114.150
121.456
129.256
129.067
112.665
105.672
104.755
111.753
122.086
117.948
129.291
119.670
113.790
121.707
129.291
128.720
CAO str.
OAH rock. + NN
str. + CO str.
Torsiyon angles (°)
OCO str. + CC str.
NN str.
CH3 rock.
CAH sci.
CH3 (methanol) rock.
CAO str.
–
–
–
–
–
984
–
–
–
–
–
841
–
715
1206
1176
1170
1159
1047
1034
1008
962
955
912
851
866
1222
1194
1162
1156
1054
1034
960
958
913
814
O(4)AC(16)AC(17)AC(18)
O(4)AC(16)AC(2)AC(1)
O(4)AC(16)AC(2)AC(3)
O(2)AC(23)AC(1)AN(2)
O(3)AC(23)AC(1)AN(2)
O(3)AC(23)AC(1)AC(2)
C(1)AN(2)AN(1)AC(10)
C(14)AC(13)AO(1)AC(24)
C(12)AC(13)AO(1)AC(24)
C(4)AC(3)AN(1)AC(10)
C(23)AC(1)AC(2)AC(16)
165.4(2)
118.0(3)
À63.0(5)
À11.3(3)
167.8(2)
À5.0(4)
166.180
113.543
113.543
À10.392
169.579
À6.874
178.182
179.151
0.763
167.396
118.756
À60.735
À11.970
167.920
À7.284
177.298
179.204
0.571
CAO (methanol) str.
CAH twist.
À179.4(2)
173.7(4)
À7.0(4)
Ring (pyrazole) breath.
Ring (phenyl) breath.
OAH out of bend.
CAH out of bend.
CAH (phenyl) vag.
OCO bend.
1.0(4)
À7.1(4)
5.535
À7.2
8.584
À3.329
–
852
775
863
838
them may be assigned to group rings CAH and CAH3 (sym., asym.).
These bands have been calculated at 3017–3027, 3035, 2871–2873,
2930–3008 cmÀ1 for HF levels, and 3080, 2993, 2909–2916, 2964–
2973 cmÀ1 for B3LYP levels. In the pyrazole, NACAC, stretching
mode was observed to be 1441 cmÀ1 as experimentally, and
1442 cmÀ1 for HF/6-31G(d) level, and 1403 cmÀ1 for B3LYP/6-
31G(d) level. Also, the other levels of calculations can be seen in
Table 4.
Other essential characteristic vibrations of the title compound
are OAH, C@O stretching. These modes have been calculated at
Fig. 4. Molecular electrostatic potential map calculated at B3LYP/6-31G(d) level.

S. Demir et al. / Journal of Molecular Structure 980 (2010) 1–6
5
0.22 ppm with B3LYP level. Since experimental 1H chemical shift
values were not available for individual hydrogen, we present
the average values for CH3 hydrogen atoms. As can be seen from
Fig. 1, molecular structure of the title compound includes hydroxyl
bounded to methanol solvent and carboxylic acid. The hydroxyl
group include oxygen atom which shows electronegative property,
and so H atom contribute to the downfield resonance. But, the H
chemical shift of OAH was experimentally not observed. The other
aromatic-H was observed to be 7–7.27 (H5–H9), 6.82–7.18 (H11–
H15) and 7.15–7.69 (H18–H22) ppm. This statement has been cal-
culated 6.89–8.12, 6.26–8 and 7.28–8.5 using HF levels, 6.44–7.7,
6.44–7.58 and 6.86–8.08 using B3LYP levels. Furthermore, the 13C
chemical shift values (with respect to TMS) are observed to be
189.34–55.47 ppm range and found to be 185.85–43.9 ppm range
by HF level and 186.53–33.51 ppm range by B3LYP.13 C NMR spec-
tra of the pyrazol compound show the signal at 55.53 ppm due to C
atom next to O1. This signal has been calculated as 46.71 ppm for
HF and 36.32 ppm for B3LYP. The signal at 143.12, 116.50 and
155.73 ppm are assigned to C atoms next to nitrogen atoms of pyr-
azol rings, respectively. The signal at 0.334 ppm is assigned to the
C16 atom next to oxygen atom (O4), respectively.
Table 5
Theorical and experimental 13C and 1H isotropic chemical shifts (with respect to TMS
all values in ppm) for the title compound.
Atom
Experimental (CDCl3)
Calculated chemical shift (ppm)
B3LYP
HF
C1
C2
C3
C4
C5
C6
C7
C8
143.12
116.50
155.73
132.03
127.60
128.90
128.10
128.63
127.60
134.25
127.28
114.00
158.75
114.02
127.25
189.34
139.82
130.51
127.28
134.99
127.60
130.52
159.75
55.53
55.47
–
137.7
118.79
138.37
118.61
130.1
113.52
116.85
112.83
117.67
123.35
117.29
93.28
150.97
104.3
118.1
186.53
130.41
118.56
111.77
115.03
112.44
117.55
147.89
36.32
33.51
8.04
139.04
117.67
143.49
123.32
130.49
123.91
127.13
123.22
128.42
126.22
127.68
103.67
152.81
113.69
128.49
185.85
132.39
128.95
122.16
131.01
122.83
127.94
155.36
46.71
43.9
C9
C10
C11
C12
C13
C14
C15
C16
C17
C18
C19
C20
C21
C22
C23
C24
C25
H2
4.2.2. Molecular electrostatic potential
Molecular electrostatic potential (MEP) is related to the elec-
tronic density and is a very useful descriptor in understanding sites
for electrophilic attack and nucleophilic reactions as well as hydro-
gen bonding interactions [30,31]. To predict reactive sites for elec-
trophilic attack for the title compound, MEP was calculated at the
B3LYP/6-31G(d) optimized geometry. The negative (red)1 regions
of MEP were related to electrophilic reactivity and the positive (blue)
ones to nucleophilic reactivity shown in Fig. 4. As easily can be seen
in Fig. 4 this molecule has three possible sites for electrophilic attack.
The negative regions are mainly over the O2, O3 and O4 atoms. For
the title compound, negative regions were calculated: the MEP value
around O4 is more negative than that of O2 and O3 atoms.
2.88
H5
H6
H7
H8
7.22
7.7
8.12
7.26
7.08
7.5
7.00
7.03
7.45
7.27
6.7
7.12
H9
7.24
6.44
6.86
H11
H12
H14
H15
H18
H19
H20
H21
H22
H24a
H25a
H55
6.82
6.44
8
6.84
6.84
7.08
7.18
6.66
6.26
7.17
7.58
6.86
7.66
6.95
7.37
7.22
6.86
7.28
7.15
7.23
7.65
7.20
7.06
7.48
7.69
8.08
8.5
4.2.3. Frontier molecular orbitals analysis
3.86
2.09
3.32
Fig. 5 shows the allotments and energy levels of the HOMO-1,
HOMO, LUMO and LUMO+1 orbitals calculated at the PBEPBE/6-
31G(d) level for the title compound. Both the highest occupied
molecular orbitals (HOMOs) and the lowest-lying unoccupied
molecular orbitals (LUMOs) are mainly located at the rings and
3.81
2.73
3.11
–
0.22
0.64
a
Average.
mostly the
p-antibonding type orbitals. The value of the energy
3181, 1670 cmÀ1 with HF/6-31G(d) and 3435, 1761, with B3LYP/6-
31G(d), these result from different substitute atoms or atom
groups in the molecular structure. As can be seen from Table 4,
there is also good agreement between experimental and theoreti-
cal vibration data for the others.
separation between the HOMO and LUMO is 2.931 eV and this en-
ergy gap indicates that the title structure is very stable.
5. Conclusion
In this work, we have calculated the geometric parameters and
vibrational frequencies of the title compound by using HF and
B3LYP methods with 6-31G(d) basis set. Also, the chemical shifts
of the title compound have been calculated by using HF and
B3LYP methods with 6-31G(d) basis set. To fit the theoretical fre-
quencies results with experimental ones for HF and B3LYP meth-
ods. In these state, geometric parameters, vibrational frequencies
and chemical shifts for diverse molecular structure analysis change
with respect to the different theoretical approaches. More com-
monly, however, the NMR spectrum is used in conjunction with
other forms of spectroscopy and chemical analysis to determinate
the structures of complicated organic molecules.
4.2.1. Assignments of the chemical shift values
DFT and HF methods differ in that no electron correlation ef-
fects are taken into account in HF. DFT methods treat the electronic
energy as a function of the electron density of all electrons simul-
taneously and thus include electron correlation effect. We have
explicitly considered the influence of the level used for the geom-
etry optimization on the final value of the title compound when
GIAO 13C and 1H c.s. calculations obtained at HF/6-31G(d) and
B3LYP/6-31G(d) levels of theory for the two optimized geometries.
The results of these calculations are tabulated in Table 5. The the-
oretical 13C and 1H chemical shift values (with respect to TMS) of
the title compound are generally compared to the experimental
13C and 1H chemical shift values. These results are also shown in
Table 5. The 1H chemical shift values (with respect to TMS) have
been calculated to be 8.5–0.64 ppm with HF level and 8.08–
1
For interpretation of color in Figs. 1–5, the reader is referred to the web version of
this article.

6
S. Demir et al. / Journal of Molecular Structure 980 (2010) 1–6
HOMO (-5.033eV)
HOMO –1 (-5.157eV)
LUMO (-2.102eV)
LUMO+1 (-1.606eV)
Fig. 5. Molecular orbital surfaces and energy levels given in parentheses for the HOMO-1, HOMO, LUMO and LUMO+1 of the title compound computed at PBEPBE/6-31G(d)
level.
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Acknowledgement
This study was supported financially by the Research Centre of
Ondokuz Mayis University (Project No: F-461).
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