FT-IR, molecular structure, first order hyperpolarizability, HOMO and LUMO analysis, MEP and NBO analysis of 2-(4-chlorophenyl)-2-oxoethyl 3-nitrobenzoate

Article abstract of DOI:10.1016/j.saa.2014.01.145

2-(4-Chlorophenyl)-2-oxoethyl 3-nitrobenzoate is synthesized by reacting 4-chlorophenacyl bromide with 3-nitrobenzoic acid using a slight excess of potassium or sodium carbonate in DMF medium at room temperature. The structure of the compound was confirmed by IR and single-crystal X-ray diffraction studies. FT-IR spectrum of 2-(4-chlorophenyl)-2-oxoethyl 3-nitrobenzoate was recorded and analyzed. The crystal structure is also described. The vibrational wavenumbers were computed using HF and DFT methods and are assigned with the help of potential energy distribution method. The first hyperpolarizability and infrared intensities are also reported. The geometrical parameters of the title compound obtained from XRD studies are in agreement with the calculated (DFT) values. The stability of the molecule arising from hyper-conjugative interaction and charge delocalization has been analyzed using NBO analysis. The HOMO and LUMO analysis are used to determine the charge transfer within the molecule. MEP was performed by the DFT method.

Full text of DOI:10.1016/j.saa.2014.01.145

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 126 (2014) 208–219
Contents lists available at ScienceDirect
Spectrochimica Acta Part A: Molecular and
Biomolecular Spectroscopy
journal homepage: www.elsevier.com/locate/saa
FT-IR, molecular structure, first order hyperpolarizability, HOMO
and LUMO analysis, MEP and NBO analysis of
2-(4-chlorophenyl)-2-oxoethyl 3-nitrobenzoate
a,c,
d
e
C.S. Chidan Kumar a, C. Yohannan Panicker b, , Hoong-Kun Fun
, Y. Sheena Mary , B. Harikumar ,
⇑
⇑
S. Chandraju f, Ching Kheng Quah a, Chin Wei Ooi a
a X-ray Crystallography Unit, School of Physics, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia
b Department of Physics, TKM College of Arts and Science, Kollam, Kerala, India
c Department of Pharmaceutical Chemistry, College of Pharmacy, King Saud University, Riyadh 11451, Saudi Arabia
d Department of Physics, Fatima Mata National College, Kollam, Kerala, India
e Department of Chemistry, TKM College of Arts and Science, Kollam, Kerala, India
f Department of Sugar Technology and Chemistry, Sir M. Visvesvaraya PG Center, University of Mysore, Tubinakere, Mandya 571402, India
h i g h l i g h t s
g r a p h i c a l a b s t r a c t
ꢀ
ꢀ
IR, single crystal XRD and NBO
analysis were reported.
The wavenumbers are calculated
theoretically using Gaussian09
software.
ꢀ
ꢀ
The wavenumbers are assigned using
PED analysis.
The geometrical parameters are in
agreement with that XRD data.
a r t i c l e i n f o
a b s t r a c t
Article history:
2-(4-Chlorophenyl)-2-oxoethyl 3-nitrobenzoate is synthesized by reacting 4-chlorophenacyl bromide
with 3-nitrobenzoic acid using a slight excess of potassium or sodium carbonate in DMF medium at room
temperature. The structure of the compound was confirmed by IR and single-crystal X-ray diffraction
studies. FT-IR spectrum of 2-(4-chlorophenyl)-2-oxoethyl 3-nitrobenzoate was recorded and analyzed.
The crystal structure is also described. The vibrational wavenumbers were computed using HF and
DFT methods and are assigned with the help of potential energy distribution method. The first hyperpo-
larizability and infrared intensities are also reported. The geometrical parameters of the title compound
obtained from XRD studies are in agreement with the calculated (DFT) values. The stability of the mole-
cule arising from hyper-conjugative interaction and charge delocalization has been analyzed using NBO
analysis. The HOMO and LUMO analysis are used to determine the charge transfer within the molecule.
MEP was performed by the DFT method.
Received 25 November 2013
Received in revised form 17 January 2014
Accepted 27 January 2014
Available online 12 February 2014
Keywords:
FT-IR
Oxoethyl
Nitro
Hyperpolarizability
Ó 2014 Elsevier B.V. All rights reserved.
⇑
Corresponding authors. Tel.: +966 1 469 5853, mobile: +91 9895370968; fax: +966 1 467 6220.
E-mail addresses: cyphyp@rediffmail.com (C.Y. Panicker), hfun.c@ksu.edu.sa (H.-K. Fun).
http://dx.doi.org/10.1016/j.saa.2014.01.145
1386-1425/Ó 2014 Elsevier B.V. All rights reserved.

C.S. Chidan Kumar et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 126 (2014) 208–219
209
Introduction
Phenacyl bromide derivatives have found vital applications
from decades in the field of synthetic chemistry [1] such as in
the synthesis of oxazoles and imidazoles [2] as well as benzoxaze-
pine [3]. In organic chemistry, phenacyl benzoate is a derivative of
an acid which is formed by the reaction between an acid and a
phenacyl bromide. They play a key role as protecting groups for
carboxylic acids in organic synthesis and biochemistry [4]. The
advantage of using these photosensitive blocking groups in general
is that, they can easily be cleaved under completely neutral and
mild conditions [4–6] and therefore were used for the identifica-
tion of organic acids. Chlorophenyl derivatives are used as indus-
trial chemical because they are lipid soluble and resistant to
metabolism. These compounds accumulate in adipose tissue. These
derivatives are used as the major metabolite of DDT, and PCBs
(Polychlorinated biphenyls) with an increased risk of breast cancer.
Muthu et al., [7] reported vibrational spectroscopic studies of
7-chloro-5-(2-chlorophenyl)-3-hydroxy-2,3-dihdro-1H-1,4-ben-
zodiazepin-2-one. Sert et al. [8] reported the vibrational analysis of
4-chloro-3-nitrobenzonitrile by quantum chemical calculations.
Tasal and Kumalar [9] reported the experimental and theoretical
investigations of a oxoethyl derivative. In the present study, IR
spectrum of 2-(4-chlorophenyl)-2-oxoethyl 3-nitrobenzoate was
reported both experimentally and theoretically. The energies, de-
grees of hybridization, populations of the lone electron pairs of
oxygen, energies of their interaction with the anti-bonding orbital
of the benzene ring and the electron density distributions and E(2)
energies have been calculated by NBO analysis using DFT method
to give clear evidence of stabilization originating from the hyper
conjugation of various intramolecular interactions. There has been
growing interest in using organic materials for nonlinear optical
devices, functioning as second harmonic generators, frequency
converters, electro-optical modulators, etc., because of the large
second order electric susceptibilities of organic materials. Since
the second order electric susceptibility is related to first hyperpo-
larizability, the search for organic chromophores with large first
hyperpolarizability is fully justified.
Fig. 1. Molecular view of 2-(4-chlorophenyl)-2-oxoethyl 3-nitrobenzoate showing
30% probability displacement ellipsoids and atom labeling scheme.
The title compound (C15H10ClNO5), crystallizes in triclinic space
group P ꢁ 1 comprises two crystallographically independent mole-
cules (A and B) in its asymmetric unit as depicted in Fig. 1. The two
benzene rings are almost coplanar to each other with dihedral an-
gles of 3.70(11)° and 5.91(11)° respectively in molecules A and B.
The maximum deviation in molecules A and B, excluding the
hydrogen atoms, are 0.168(3) Å and 0.195(3) Å at O4 atom, respec-
tively. In the crystal structure (Fig. 2), the intermolecular
C3A–H3AAꢂ ꢂ ꢂO5B, C3B–H3BAꢂ ꢂ ꢂO5A, C11A–H11Aꢂ ꢂ ꢂO3B, C11B–
H11Bꢂ ꢂ ꢂO3A and C14A–H14Aꢂ ꢂ ꢂO1B hydrogen bonds (Table 2) link
the molecules into sheets running along (101). In the sheet, there
are R22 (14), R44 (28) and R44 (36) ring motifs [12] which are generated
through these hydrogen bond interactions. Furthermore, the crys-
tal is consolidated by Van Der Waals interactions. The crystal data
and parameters for structure refinement of the title compound are
given in Table 1. H-bonding interactions are listed in Table 2.
Crystallographic data for the compound has been deposited at
the Cambridge Crystallographic Data Centre with the CCDC No:
942744. FT-IR spectrum (Fig. 3) of the compound was recorded
as KBr pellets in the region of 4000–400 cmꢁ1 with Perkin–Elmer
spectrum GX.
Experimental synthesis of 2-(4-chlorophenyl)-2-oxoethyl 3-
nitrobenzoate
Computational details
The vibrational frequencies and IR intensities were calculated at
DFT(B3LYP) and HF methods by using the Gaussian09 software
The reagents and solvents for the synthesis were obtained from
the Aldrich Chemical Co., and were used without additional purifi-
cation. 2-Bromo-1-(4-chlorophenyl)ethanone (0.002 mol) was re-
acted with 3-nitrobenzoic acid (0.003 mol) in presence of
potassium carbonate in dimethyl formamide (10 ml) at room tem-
perature for about 2 h. The progress of the reaction was monitored
by TLC. After completion of the reaction, the reaction mixture was
poured into ice-cold water. The solid product obtained was filtered,
washed with water and recrystallized from ethanol. Crystals suit-
able for X-ray diffraction studies were grown in a mixture of ace-
tone/ethanol (1:1 v/v) by the slow evaporation technique.
Melting point was determined by Stuart Scientific (UK) apparatus.
The purity of the compound was confirmed by thin layer chroma-
tography using Merck silica gel 60 F254 coated aluminum plates.
X-ray analysis was done using Bruker SMART Apex II DUO CCDC
diffractometer. The data were processed with SAINT and corrected
for absorption using SADABS [10]. The structure was solved by di-
rect method using the program SHELXTL [11] and were refined by
full-matrix least squares technique on F2 using anisotropic dis-
placement parameters. The non-hydrogen atoms were refined
anisotropically. In this compound, all the H atoms were calculated
geometrically with isotropic displacement parameters set to 1.2
times the equivalent isotropic U values of the parent carbon atoms.
Fig. 2. Crystal structure of 2-(4-chlorophenyl)-2-oxoethyl 3-nitrobenzoate with
intermolecular hydrogen bonding patterns shown as dashed lines. Hydrogen atoms
not involved in intermolecular interaction have been omitted for clarity.

210
C.S. Chidan Kumar et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 126 (2014) 208–219
Table 1
modes; therefore scaling factor of 0.9613 has to be used for obtain-
ing a considerably better agreement with experimental data [14].
The assignments of the calculated wavenumbers are aided by ani-
mation option of Gaussview graphical interface for Gaussian pro-
gram, which gives a visual presentation of the shapes of the
vibrational modes [15]. The potential energy distribution (PED) is
calculated with the help of GAR2PED software package [16].
Parameters corresponding to optimized geometry (DFT) of the title
compound (Fig. 4) are given in Table 3.
Crystal data and parameters for structure refinement of the title compound.
CCDC
942744
C15H10ClNO5
319.69
Triclinic
P ꢁ 1
Molecular formula
Molecular weight
Crystal system
Space group
a (Å)
9.2584(10)
12.1055(18)
14.1230(18)
100.787(4)
100.202(11)
106.206(5)
1448.3(3)
4
b (Å)
c (Å)
a
(°)
b (°)
c
(°)
V (Å3)
Results and discussion
Z
Dcalc (g cmꢁ3
)
1.466
IR spectrum
Crystal dimensions (mm)
(mmꢁ1
Radiation k (Å)
0.83 ꢃ 0.27 ꢃ 0.13
l
)
0.29
The calculated (scaled wavenumbers), observed IR bands and
assignments are given in Table 4. C@O stretching vibration is ex-
pected in the range 1715–1680 cmꢁ1 [17]. In the present case very
strong C@O experimental bands are observed at 1728, 1703 cmꢁ1
in the IR spectrum and the theoretical values are 1739,
1720 cmꢁ1. These assignments were also supported by the litera-
tures [18,19]. The in-plane C@O and out-of-plane C@O are ex-
pected in the regions, 725 95 and 595 85 cmꢁ1, respectively
[17]. These bands are assigned at 746, 650, 532 cmꢁ1 in the IR spec-
trum and at 747, 652, 618, 542 cmꢁ1 theoretically (DFT). The COC
stretching vibrations are expected in the ranges 1200–1100 cmꢁ1
(asymmetric) and 1050–950 cmꢁ1 (symmetric) [17,20]. The skele-
tal CAO deformation can be found in the region 320 50 cmꢁ1
[21]. As expected the asymmetric COC vibration is assigꢁn1ed at
1120 cmꢁ1 in the IR spectrum with DFT value at 1133 cm . The
symmetric COC stretching vibration is assigned at 1042 cmꢁ1 the-
oretically for the title compound [22]. Arjunan et al. [23] reported
the bands at 1262 cmꢁ1 in IR and 1267 cmꢁ1 in Raman as the COC
asymmetric stretching modes and the symmetric COC stretching
mode at 924 cmꢁ1 in IR and 920 cmꢁ1 in Raman spectrum. The
deformation modes of COC are reported at 604, 606, and
287 cmꢁ1 experimentally [23].
0.71073
Table 2
Hydrogen bond geometries of the title compound.
DAHꢂ ꢂ ꢂA
d(DAH) (Å)
d(HAA) (Å)
d(DAA) (Å)
\DHA (°)
C3AAH3AAꢂ ꢂ ꢂO5Bi
C3BAH3BAꢂ ꢂ ꢂO5Aii
C11AAH11Aꢂ ꢂ ꢂO3Biii
C11BAH11Bꢂ ꢂ ꢂO3Aiv
C14AAH14Aꢂ ꢂ ꢂO1Bv
0.93
0.93
0.93
0.93
0.93
2.60
2.57
2.53
2.59
2.57
3.325(4)
3.313(3)
3.220(3)
3.278(3)
3.207(3)
135.0
137.0
132.0
131.0
126.0
Symmetry codes: (i) x, 1 + y, (ii) 1 + z; x, y, ꢁ1 + z; (iii) 1 + x, y, z; (iv) ꢁ1 + x, ꢁ1 + y, z;
and (v) 1 + x, 1 + y, z.
The most characteristics bands in the spectra of nitro com-
pounds are due to the NO2 stretching vibrations, which are the
two most useful group vibrations, not only because of their spec-
tral positions but also for their strong intensities [17]. Nitro ben-
zene derivatives show NO2 asymmetric stretching modes in the
region 1535 30 cmꢁ1 and 3-nitro pyridines [17,24] at
1530 20 cmꢁ1. In substituted nitro benzenes [17,24]
pears strongly at 1345 30 cmꢁ1
The bands seen at 1570,
tsNO2 ap-
.
1348 cmꢁ1 in the IR spectrum and at 1565, 1346 cmꢁ1 (DFT) are as-
signed the NO2 stretching modes. Sundraganesan et al. [25] re-
ported the asymmetric and symmetric NO2 stretching modes at
1600, 1572 cmꢁ1 and 1371, 1319 cmꢁ1, respectively. Raj et al.
[26] reported NO2 stretching modes 1621, 1582, 1526, 1328 cmꢁ1
in the IR spectrum and at 1601, 1585, 1561, 1532, 1347, 1343,
1332 cmꢁ1 theoretically. When conjugated to aromatic molecules,
the NO2 scissoring mode occurs at higher wavenumbers
(850 60 cmꢁ1). In aromatic compounds the wagging mode of
NO2 is assigned at 740 50 cmꢁ1 [17]. The rocking mode of NO2
is active in the region 540 70 cmꢁ1 in aromatic nitro compounds
[17]. The deformation modes of NO2 are reported at 744 (IR), 821,
703, 716 (DFT) and at 839 cmꢁ1 (Raman) [26]. The bands at 788,
573, 464 cmꢁ1 in the IR spectrum and at 799, 559, 465 cmꢁ1
(DFT) are assigned as the NO2 deformation bands for the title com-
pound. Aromatic nitro compounds show a CAN stretching vibra-
tion [22,27] near 870 cmꢁ1. In the present case band at 911 (IR)
and at 906 cmꢁ1 (DFT) is assigned as CN stretching mode.
Fig. 3. FT-IR spectrum of 2-(4-chlorophenyl)-2-oxoethyl 3-nitrobenzoate.
package [13]. The wavenumber values computed at the Hartree–
Fock level contain known systematic errors due to the negligence
of electron correlation [14]. Therefore, we have used the scaling
factor value of 0.8929 for HF/6-31G⁄ basis set. The DFT hybrid
B3LYP functional method tends to overestimate the fundamental
The CH2 stretching modes are expected in the range 2950–
2860 cmꢁ1 [17,28]. For the assignments of CH2 group frequencies,
basically six fundamentals can be associated to each CH2 group

C.S. Chidan Kumar et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 126 (2014) 208–219
211
Fig. 4. Optimized structure of (DFT) 2-(4-chlorophenyl)-2-oxoethyl 3-nitrobenzoate.
Table 3
Geometrical parameters of 2-(4-chlorophenyl)-2-oxoethyl 3-nitrobenzoate, atom labeling according to Fig. 4.
Bond lengths (Å)
Label
Bond angles (°)
Torsion angles (°)
DFT
XRD
Label
DFT
XRD
Label
DFT
XRD
C12ACl1
C18AO2
C19AO3
C22AO3
C22AO4
N7AO5
N7AO6
C30AN7
C8AH9
1.8170
1.2485
1.4563
1.3826
1.2440
1.2792
1.2777
1.4799
1.0862
1.4047
1.4155
1.0849
1.4029
1.4047
1.0850
1.4020
1.0858
1.4152
1.4978
1.5316
1.0979
1.0979
1.4894
1.4136
1.4079
1.0849
1.4064
1.0857
1.4046
1.0843
1.4070
1.4009
1.0846
1.7332
1.2112
1.4362
1.3922
1.2012
1.2114
1.2124
1.4843
0.9300
1.3823
1.4013
0.9300
1.3793
1.3773
0.9300
1.3823
0.9300
1.3953
1.4893
1.5063
0.9700
0.9700
1.4923
1.3873
1.3883
0.9300
1.3893
0.9300
1.3474
0.9300
1.3794
1.3593
0.9300
A(19,3,22)
A(5,7,6)
A(5,7,30)
A(6,7,30)
A(9,8,10)
117.1
123.9
117.9
118.2
118.1
121.2
120.6
120.8
118.8
120.4
119.0
119.1
122.0
120.4
118.7
120.9
120.6
120.8
118.6
119.1
122.7
118.1
121.7
121.5
116.8
108.2
109.7
109.7
110.8
110.8
107.7
122.8
111.6
125.6
121.4
118.1
120.5
119.1
119.9
121.0
119.9
120.4
119.7
121.9
118.6
119.6
118.8
118.9
122.4
118.3
120.7
121.0
114.1
122.8
118.5
118.6
119.7
119.7
120.7
120.4
119.2
120.4
119.5
119.0
121.5
120.3
119.3
120.3
119.7
120.7
119.7
118.6
122.4
119.0
122.1
121.2
116.7
108.7
110.0
110.0
110.0
110.0
108.3
123.4
112.5
124.1
123.0
117.0
120.0
120.1
119.7
120.1
119.7
120.6
119.7
121.0
118.0
121.0
118.8
117.9
123.2
118.4
120.8
120.8
D(22,3,19,18)
D(19,3,22,4)
D(19,3,22,23)
D(5,7,30,28)
D(5,7,30,31)
D(6,7,30,28)
ꢁ180.0
ꢁ0.0
ꢁ180.0
ꢁ0.0
ꢁ180.0
180.0
0.0
ꢁ175.6
3.8
ꢁ176.6
1.3
ꢁ172.2
178.5
0.0
A(9,8,17)
A(10,8,17)
A(8,10,11)
A(8,10,12)
A(11,10,12)
A(1,12,10)
A(1,12,13)
A(10,12,13)
A(12,13,14)
A(12,13,15)
A(14,13,15)
A(13,15,16)
A(13,15,17)
A(16,15,17)
A(8,17,15)
A(8,17,18)
A(15,17,18)
A(2,18,17)
A(2,18,19)
A(17,18,19)
A(3,19,18)
A(3,19,20)
A(3,19,21)
A(18,19,20)
A(18,19,21)
A(20,19,21)
A(3,22,4)
A(3,22,23)
A(4,22,23)
A(22,23,24)
A(22,23,31)
A(24,23,31)
A(23,24,25)
A(23,24,26)
A(25,24,26)
A(24,26,27)
A(24,26,28)
A(27,26,28)
A(26,28,29)
A(26,28,30)
A(29,28,30)
A(7,30,28)
A(7,30,31)
A(28,30,31)
A(23,31,30)
A(23,31,32)
A(30,31,32)
D(6,7,30,31)
D(17,8,10,12)
D(10,8,17,18)
D(8,10,12,1)
D(8,10,12,13)
D(10,12,13,14)
D(10,12,13,15)
D(12,13,15,17)
D(13,15,17,8)
D(8,17,18,2)
D(8,17,18,19)
D(15,17,18,2)
D(15,17,18,19)
D(2,18,19,3)
D(17,18,19,3)
D(3,22,23,24)
D(3,2,23,31)
D(4,22,23,24)
D(4,22,23,31)
D(22,23,24,26)
D(31,23,24,26)
D(22,23,31,30)
D(22,23,31,32)
D(23,24,26,28)
D(26,28,30,7)
D(26,28,30,31)
D(7,30,31,23)
D(28,30,31,23)
D(2,18,19,20)
D(2,18,19,21)
D(17,18,19,20)
D(17,18,19,21)
D(22,3,19,20)
D(22,3,19,21)
D(9,8,10,11)
0.0
ꢁ0.5
ꢁ180.0
ꢁ180.0
0.0
ꢁ174.8
ꢁ180.0
C8AC10
C8AC17
ꢁ.07
C10AH11
C10AC12
C12AC13
C13AH14
C13AC15
C15AH16
C15AC17
C17AC18
C18AC19
C19AH20
C19AH21
C22AC23
C23AC24
C23AC31
C24AH25
C24AC26
C26AH27
C26AC28
C28AH29
C28AC30
C30AC31
C31AH32
ꢁ180.0
ꢁ178.8
1.2
0.0
ꢁ0.0
0.0
ꢁ180.0
ꢁ0.0
0.0
ꢁ0.9
ꢁ0.1
173.5
ꢁ6.2
ꢁ5.2
175.1
2.9
ꢁ177.4
ꢁ3.2
176.6
176.6
ꢁ3.7
ꢁ179.3
1.0
180.0
ꢁ0.5
ꢁ0.8
ꢁ178.0
0.2
178.2
ꢁ0.1
–
180.0
0.0
ꢁ180.0
ꢁ0.0
180.0
ꢁ180.0
0.0
ꢁ180.0
0.0
180.0
ꢁ0.0
0.0
ꢁ180.0
0.0
180.0
0.0
120.3
ꢁ120.3
ꢁ59.7
59.7
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
59.0
ꢁ59.0
0.0
D(9,8,10,12)
D(17,8,10,11)
D(9,8,17,15)
ꢁ180.0
180.0
ꢁ180.0
0.0
D(9,8,17,18)
D(10,8,17,15)
D(11,10,12,1)
D(11,10,12,13)
D(1,12,13,14)
D(1,12,13,15)
D(12,13,15,16)
D(14,13,15,16)
ꢁ0.0
0.0
ꢁ180.0
0.0
180.0
180.0
0.0
–

212
C.S. Chidan Kumar et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 126 (2014) 208–219
Table 4
Vibrational assignments of 2-(4-chlorophenyl)-2-oxoethyl 3-nitrobenzoate.
HF/6-31G⁄
B3LYP/6-31G⁄
IR
Assignments
–
t
IRI
10.56
1.48
1.53
1.86
3.15
0.97
6.76
8.87
10.93
27.75
106.13
485.92
388.82
42.40
109.63
68.48
16.36
18.38
55.29
78.06
106.72
189.00
52.45
7.71
t
IRI
t
3081
3071
3053
3053
3044
3037
3029
3023
2947
2903
1793
1783
1670
1610
1609
1589
1575
1495
1479
1470
1466
1429
1406
1387
1306
1298
1282
1257
1211
1205
1171
1158
1153
1123
1094
1079
1076
1073
1054
1025
1009
996
3136
3128
3113
3108
3106
3096
3088
3083
2976
2939
1739
1720
1615
1584
1579
1565
1558
1478
1465
1452
1424
1392
1353
1346
1326
1298
1285
1270
1251
1219
1200
1167
1156
1133
1098
1078
1068
1067
1042
993
8.55
1.79
2.19
2.69
2.34
0.14
6.72
7.07
7.37
–
–
–
–
–
3096
–
3042
–
2933
1728
1703
1617
1587
1570
1570
1559
1447
–
t
t
t
t
t
t
t
t
t
t
t
t
t
t
t
t
t
t
t
CHI(98)
CHI(95)
CHI(97)
CHII(100)
CHII(92)
CHII(94)
CHI(98)
CHII(97)
asCH2(100)
sCH2(96)
C@O(78)
C@O(81)
39.13
129.54
222.39
85.08
123.87
16.91
113.38
20.01
11.86
1.70
PhI(65),
PhII(58),
PhI(62),
t
t
t
PhII(17)
PhI(20)
PhII(16)
asNO2(59),
t
PhII(22)
PhI(23)
PhII(19)
PhII(60),
PhI(63),
PhII(60),
t
t
t
PhI(12)
6.74
1441
–
dCH2(57),
t
PhII(23)
33.97
36.45
47.31
305.36
1.79
t
t
PhII(55),
PhI(58),
t
t
t
t
PhI(17)
PhII(12), dCH2(13)
sNO2(22)
PhI(20)
PhII(24)
PhII(44), dCHII(23)
1400
1370
1348
1322
–
1284
1267
1242
1220
–
1175
1148
1120
1102
1088
1070
1058
1042
1008
–
–
970
–
–
940
–
925
911
851
832
819
788
771
746
717
699
–
dCH2(52),
t
t
t
sNO2(49),
PhI(46),
679.12
29.42
125.34
1.22
276.92
6.10
t
1.48
1.42
dCHII(50), dCHI(18)
dCHI(52), dCHII(14), dCH2(13)
dCH2(48), dCHI(13)
dCHI(52), dCH2(14), dCHII(11)
dCH2(33), dCHII(36)
dCHII(43), dCHI(24)
146.72
359.40
0.44
388.57
26.50
1.34
2.49
124.79
53.25
97.73
7.19
106.82
18.49
10.93
6.50
0.00
0.52
0.07
7.93
0.97
4.38
0.20
1.04
132.34
1.68
57.61
17.89
34.70
0.60
dCHI(45),
tCOC(22)
343.98
7.15
tCOC(42), dCHI(16), dCHII(13)
dCHII(52), dCHI(19)
dCHI(55), dCHII(22)
dCHII(48), dCHI(18)
8.81
70.94
85.92
5.89
10.77
0.62
dCHI(39),
t
COC(24)
PhI(21)
PhI(51), dPhI(16)
CHI(22), dCH2(17)
CC(38), dCH2(18), CHI(12),
CHI(32), dCH2(29)
CC(39), dCHII(32), dCH2(24)
CC(33), CHI(25)
CHII(17)
t
t
COC(44), t
981
978
976
953
953
942
933
923
906
837
822
808
799
766
747
709
dPhI(35), c
0.17
0.55
6.65
t
c
t
t
c
c
c
c
cCHII(11)
994
989
978
977
969
961
924
860
852
835
831
784
772
738
716
708
171.44
3.44
c
CHI(65),
CHII(28),
CHII(55), c
c
3.54
0.36
1.24
c
CHI(24)
CHI(13)
CN(38)
dCH2(34),
CHI(39),
CHII(60)
t
t
42.44
17.40
9.04
21.82
9.35
c
c
c
PhII(44)
CHII(55), dNO2(22)
CHI(18)
CHI(24), dC@O(19), cPhI(15)
dNO2(41), c
1.42
c
14.10
124.11
51.42
0.46
49.87
4.70
3.10
dC@O(47),
c
PhI(17)
PhII(27), dC@O(13)
PhI(34), dCH2(20), CHII(18)
CHII(22), dPhII(18)
CCl(35), dPhII(22), dC@O(17)
dC@O(38), dPhII(25), dPhI(19)
dPhII(22), C@O(21), dPhI(15)
31.72
67.02
0.00
29.94
0.01
c
c
PhI(26), c
703
695
677
652
641
618
c
dCH2(23), c
t
685
651
641
617
660
650
628
–
4.05
0.94
2.04
0.94
c
c
C@O(32),
s
PhI(20),
s
PhII(14)
572
541
509
500
467
464
428
423
26.20
1.92
49.50
16.27
0.89
1.51
1.26
0.01
0.01
559
542
510
497
465
454
428
420
13.31
1.13
45.54
6.99
0.02
2.11
1.75
0.03
0.00
1.56
573
532
513
–
464
448
–
420
–
–
dNO2(32),
s
s
s
PhI(18),
PhI(23),
PhI(17),
s
s
s
s
PhII(16)
PhII(17)
PhII(15), cC@O(41)
c
C@O(40),
dNO2(18),
PhI(25),
dNO2(33),
PhI(25), dCCl(21), dCO(17)
dCCl(33), PhII(16), PhI(15)
PhII(25), PhI(19), dCO(15)
CCl(21), PhI(10),
PhII(15)
CO(13)
c
c
C@O(16), PhII(13), dNO2(11)
c
PhI(20), cPhII(18)
c
c
s
c
s
407
390
332
401
386
330
dCO(28),
CCl(30),
PhI(25),
c
s
sPhII(10)
5.07
5.94
c
s
s
PhI(13),
s
6.57
–
s
PhII(24), c

C.S. Chidan Kumar et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 126 (2014) 208–219
213
Table 4 (continued)
HF/6-31G⁄
B3LYP/6-31G⁄
IR
Assignments
–
t
IRI
t
IRI
t
315
306
266
254
208
198
175
135
129
98
88
62
44
38
31
22
14
3.06
313
303
263
249
208
197
172
135
126
97
87
57
49
41
30
19
12
2.00
9.51
1.98
0.00
2.77
9.02
4.89
0.99
0.48
1.08
3.01
1.04
0.81
0.01
1.37
2.26
1.30
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
c
c
CCl(27),
CO(33),
s
c
PhI(19),
CCl(17),
PhI(22),
C@O(21),
s
PhII(13)
10.05
1.84
0.04
2.63
9.77
7.85
0.97
0.43
1.12
3.22
3.34
0.54
0.19
1.55
3.23
0.30
s
PhI(12), sPhII(11)
s
C@O(28),
CCl(27),
dCC(22),
PhI(17),
CC(28),
s
s
PhII(21)
c
s
s
PhI(17), sPhII(11)
s
NO2(20),
s
s
s
PhI(14)
s
c
s
PhII(11),
c
CC(28)
C@O(17)
CC(18)
CC(28)
sNO2(20),
s
s
s
s
s
s
s
s
s
s
PhI(27),
PhI(17),
CC(27),
PhI(21),
s
s
PhII(21),
PhII(11),
c
s
CCl(18),
PhII(19),
PhI(17), s
s
NO2(14)
CH2(18)
PhII(11)
s
s
NO2(27),
s
PhI(32),
PhI(20),
PhI(27),
C@O(33),
PhI(29),
s
s
s
PhII(22),
PhII(19),
PhII(22),
s
s
s
CH2(23)
NO2(17)
C@O(27)
sPhI(20),
sPhII(13)
s
PhII(18),
s
CH2(13)
t
– Stretching; d – in-plane deformation;
c
– out-of-plane deformation; s – twisting; PhI – 1,3-substitued benzene; PhII – 1,4-substitued benzene; as – asymmetric; s –
symmetric; potential energy distribution is given in brackets in the assignment column; IRI – IR intensity.
names CH2 asymmetric stretch, CH2 symmetric stretch, CH2 scis-
soring, CH2 wagging, CH2 twisting and CH2 rocking modes. In this
study, the FT-IR band at 2933 cmꢁ1 has been assigned to CH2
stretching modes. The theoretically computed values of CH2
stretching give 2976 and 2939 cmꢁ1. The deformation modes of
CH2 are assigned at 1452, 1353, 1251, 906 cmꢁ1 theoretically and
bands are observed in the IR spectrum at 1441, 1370, 1242,
bers and the greater the number of substituents on the ring, the
broader the absorption regions [17]. In the case of C@O substitu-
tion, the band near 1490 cmꢁ1 can be very weak [17]. The fifth ring
stretching mode is active near 1315 65 cmꢁ1, a region that over
laps strongly with that of the CH in-plane deformation [17]. The
sixth ring stretching mode, the ring breathing vibration appears
as a weak band near 1000 cmꢁ1 in mono, 1,3-di and 1,3,5-trisub-
stitued benzenes. In the otherwise substituted benzenes, however,
this mode is substituent sensitive and difficult to distinguish from
the other modes.
911 cmꢁ1
.
The aliphatic CACl bands absorb at 830–560 cmꢁ1 [29]. The CCl2
stretching mode is reported at around 738 cmꢁ1 for dichlorometh-
ane and scissoring mode of CCl2 at around 284 cmꢁ1 [30,31].
For the 1,4-substitued phenyl ring, the ring stretching modes
Pazdera et al. [31,32] reported CACl stretching mode at 890 cmꢁ1
.
t
Ph modes are expected in the range 1280–1620 cmꢁ1 [17]. In
For 2-cyanophenylisocyanide dichloride, the CACl stretching mode
was reported at 870 cmꢁ1 in IR and at 882 cmꢁ1 theoretically [33].
Arslan et al. [34] reported CACl stretching mode at 683 cmꢁ1
(experimental) and at 711, 687, 697 cmꢁ1 theoretically. The defor-
mation bands of CACl are reported at 431, 435, 441, 443 cmꢁ1
[33,34]. In the present case, the band at 660 (IR) and 677 cmꢁ1
(DFT) is assigned as the stretching mode of CACl which is not pure
but contains a significant contribution from other modes. The
the present case tPhII modes are assigned at 1584, 1558, 1465,
1424, 1298 cmꢁ1 theoretically (DFT) and observed at 1587,
1559 cmꢁ1 in the IR spectrum. The ring breathing mode for the
1,4-substituted benzenes with entirely different substituents [30]
have been reported to be strongly IR active with typical bands in
the interval 740–840 cmꢁ1. For the title compound, this is con-
firmed by the strong band in the infrared spectrum at 851 cmꢁ1
which finds support from the computational result at 837 cmꢁ1
.
deformation bands of CACl are assigned below 600 cmꢁ1
.
Ambujakshan et al. [41] reported 792 (IR) and 782 cmꢁ1 (HF) as
the ring breathing mode for para substituted benzenes.
As the identification of all the normal modes of vibration of
large molecules is not easy, we tried to simplify the problem by
considering each molecule as substituted benzene. Such an idea
has already been successfully utilized for the vibrational assign-
ment of molecules containing homo- and hetero-aromatic rings
[35–37]. In the following discussion, the 1,3-di and 1,4-disubsti-
tuted benzene ring are designated as PhI and PhII, respectively.
The modes of the two phenyl rings will differ in wavenumber
and the magnitude of splitting will depend on the strength of inter-
action between different parts (internal co-ordinates) of the two
rings. For some modes, this splitting was so small that they may
be considered as quasi-degenerate, whereas for other modes a sig-
nificant amount of splitting is observed [26,38,39].
The bands observed at 1617, 1570, 1477, 1400, 1322 cmꢁ1 in
the IR spectrum and at 1615, 1579, 1478, 1392, 1326 cmꢁ1 theoret-
ically (DFT) are assigned as the ring stretching modes of the phenyl
ring PhI. These bands are expected in the range 1620–1280 cmꢁ1
[17]. For the 1,3-disubstituted benzene ring, the ring breathing
mode is observed experimentally at 1008 cmꢁ1 in the IR spectrum
and the calculated value is 993 cmꢁ1 as expected [17,30]. For
substituted benzenes, the in-plane CH deformations are expected
above 1000 cmꢁ1 [17]. Bands observed at 1267, 1148, 1088,
1058 cmꢁ1 and at 1284, 1175, 1102, 1070 cmꢁ1 in the IR spectrum
are assigned as dCH modes of the rings PhI and PhII, respectively.
The corresponding theoretical values (DFT) are 1270, 1156, 1078,
1067 cmꢁ1 and 1285, 1167, 1098, 1068 cmꢁ1 for PhI and PhII,
respectively.
The phenyl CH stretching modes occur above 3000 cmꢁ1 and
are typically exhibited as multiplicity of weak to moderate bands
compared with the aliphatic CH stretching [40]. In the present case,
the DFT calculations give CH stretching modes of the phenyl rings
in the range 3083–3136 cmꢁ1 and the bands are observed at 3042,
3096 cmꢁ1 in the IR spectrum.
The benzene ring possesses six ring stretching modes of which
the four with the highest wavenumbers occurring near 1600, 1580,
1490 and 1440 cmꢁ1 are good group vibrations [17]. With heavy
substituents, the bands tend to shift to somewhat lower wavenum-
Generally, the out-of-plane CH deformations of the phenyl rings
with the highest wavenumbers have a weaker intensity than those
absorbing at lower wavenumbers. The
cCH modes are observed
between 1000 and 700 cmꢁ1 [17]. These modes are mainly deter-
mined by the number of adjacent hydrogen atoms on the ring.
Although strongly electron attracting substituent groups, such as
nitro-, can result in an increase (about 30 cmꢁ1) in the frequency
of the vibration, these vibrations are not very much affected by

214
C.S. Chidan Kumar et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 126 (2014) 208–219
the nature of substituents. A very strong CH Out of plane deforma-
tion band occurring at 840 50 cmꢁ1 is typical for 1,4-disubstitued
benzenes [17]. For the title compound, a very strong CH is observed
at 832 cmꢁ1 in the IR spectrum. The DFT calculations give this
mode at 822 cmꢁ1. The 1,3-susbtitued benzene resembles that of
tive bonds leading to stabilization of 10.69 kcal molꢁ1. Another
intramolecular hyper-conjugative interactions are formed by the
orbital overlap between n(O) and r⁄(CAC) bond orbitals which re-
sults in ICT causing stabilization of the system. The strong intramo-
lecular hyper-conjugative interaction of
C18AC19 from O2 of
mono substitution, with out-of-plane
c
CH vibration near
n2(O2) ? r⁄(C18AC19) which increases ED (0.06602e) that weak-
770 cmꢁ1 and out-of-plane ring vibration
c
Ph in the neighborhood
ens the respective bonds leading to stabilization of
of 685 cmꢁ1 [17]. These bands are observed at 771, 699 cmꢁ1 in the
IR spectrum and finds support from computational results, at 766,
703 cmꢁ1 for the phenyl ring PhI [17]. The bands observed at 970,
940, 925, 851, 832, 819, 771 cmꢁ1 in the IR spectrum are assigned
as the out-of-plane CH modes of the phenyl rings I and II. The sub-
stituent sensitive modes of the phenyl ring and other modes are
also identified and assigned (Table 4).
20.71 kcal molꢁ1
. The strong intramolecular hyper-conjugative
interaction of O4AC22 from O3 of n2(O3) ? p⁄(O4AC22) which in-
creases ED (0.26267e) that weakens the respective bonds leading
to stabilization of 44.92 kcal molꢁ1. Also another intramolecular
hyper-conjugative interactions are formed by the orbital overlap
between n(O) and r⁄(OAC) bond orbital which results in ICT caus-
ing stabilization of the system. The strong intramolecular hyper-
In order to investigate the performance of vibrational wave-
numbers of the title compound, the root mean square (RMS) value
between the calculated and observed wavenumbers were calcu-
lated. The RMS values of wavenumbers were calculated using the
following expression [42]
conjugative interaction of O3AC22 from O4 of n2(O4) ? r⁄(O3AC22
)
which increases ED (0.10326e) that weakens the respective bonds
leading to stabilization of 32.43 kcal molꢁ1. A very strong hyper-
conjugative interaction of O6AN7 from O5 of n3(O5) ? r⁄(O6AN7)
which increases ED (0.65474e) that weakens the respective bonds
leading to stabilization of 167.09 kcal molꢁ1. Also hyper-conjuga-
tive interaction of C30AN7 from O6 of n2(O6) ? r⁄(C30AN7) which
increases ED (0.10341e) that weakens the respective bonds leading
to stabilization of 10.61 kcal molꢁ1. The increased electron density
at the oxygen and chlorine atoms leads to the elongation of respec-
tive bond length and a lowering of the corresponding stretching
wavenumber. The electron density (ED) is transferred from the
n(Cl) to the anti-bonding p⁄ orbital of the CAC, n(O) to r⁄(NAC),
p⁄(OAC), p⁄(OAN) and n(O) to r⁄(NAC) explaining both the elon-
gation and the red shift [46]. The CACl, AC@O, ANO2 stretching
modes can be used as a good probe for evaluating the bonding con-
figuration around the corresponding atoms and the electronic dis-
tribution of the benzene molecule. Hence the title compound is
stabilized by these orbital interactions.
The NBO analysis also describes the bonding in terms of the nat-
ural hybrid orbital n2(Cl1), which occupy a higher energy orbital
(ꢁ0.33396 a.u.) with considerable p-character (100%) and low
occupation number (1.97665 a.u.) and the other n1(Cl1) occupy a
lower energy orbital (ꢁ0.95238 a.u.) with p-character (15.60%)
and high occupation number (1.98983 a.u.). Also n2(O2), which oc-
cupy a higher energy orbital (ꢁ0.29058 a.u.) with considerable p-
character (99.89%) and low occupation number (1.89899 a.u.) and
the other n1(O2) occupy a lower energy orbital (ꢁ0.70762 a.u.)
with p-character (37.84%) and high occupation number
(1.97679 a.u.). n2(O3), which occupy a higher energy orbital
(ꢁ0.35390 a.u.) with considerable p-character (100.0%) and low
occupation number (1.80152 a.u.) and the other n1(O3) occupy a
lower energy orbital (ꢁ0.58895 a.u.) with p-character (57.33%)
and high occupation number (1.96676 a.u.). Again n2(O4), which
occupy a higher energy orbital (ꢁ0.29782 a.u.) with considerable
p-character (100.0%) and low occupation number (1.86271 a.u.)
rffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi
X
À
Á
1
n
i
2
RMS ¼
tci alc
ꢁ
tei xp
:
n ꢁ 1
The RMS error of the observed IR bands is found to 27.57 for HF
and 11.43 for DFT methods, respectively. The small differences be-
tween experimental and calculated vibrational modes are ob-
served. This is due to the fact that experimental results belong to
solid phase and theoretical calculations belong to gaseous phase.
NBO analysis
In NBO analysis, the input atomic orbital basis set is trans-
formed via natural atomic orbitals and natural hybrid orbitals into
natural bond orbitals. The NBOs obtained in this fashion corre-
spond to the widely used Lewis picture, in which two center bonds
and lone pairs localized [43]. The natural bond orbitals (NBO) cal-
culations were performed using NBO 3.1 program [44] as imple-
mented in the Gaussian09 package at the DFT/B3lYP level in
order to understand various second order interactions between
the filled orbitals of one subsystem and vacant orbitals of another
subsystem. In the NBO analysis, the electronic wave functions are
interpreted in terms of a set of Lewis and a set of non-Lewis local-
ized orbitals [45]. Delocalization effects can be identified from the
presence of off diagonal elements of the Fock matrix in the NBO ba-
sis. The output obtained by the second order perturbation theory
analysis is normally the first to be examined by the experience
NBO user in searching for significant delocalization effects. How-
ever the strength of these delocalization interactions E(2) are esti-
mated by the second order perturbation theory as estimated by the
equation
2
and the other n1(O4) occupy
a
lower energy orbital
ðFi;jÞ
Eð2Þ ¼ Eij ¼ qi
D
(ꢁ0.72047 a.u.) with p-character (36.23%) and high occupation
number (1.97575 a.u.). Also n2(O5), which occupy a higher energy
orbital (ꢁ0.31340 a.u.) with considerable p-character (99.81%) and
low occupation number (1.91246 a.u.) and the other n1(O5) occupy
a lower energy orbital (ꢁ0.83453 a.u.) with p-character (19.55%)
and high occupation number (1.97776 a.u.). Thus, a very close to
pure p-type lone pair orbital participates in the electron donation
to the r⁄(CAC) orbital for n2(Cl1) ? r⁄(CAC) and n(O) to r⁄(NAC),
p⁄(OAC), p⁄(OAN) and n(O) to r⁄(NAC) interactions in the com-
pound. The results are given in Table 6.
ðEj ꢁ EiÞ
where qi is the donor orbital occupancy, Ei, Ej the diagonal elements,
and Fij is the off diagonal NBO Fock matrix element.
In NBO analysis large E(2) value shows the intensive interaction
between electron-donors and electron-acceptors and greater the
extent of conjugation of the whole system, the possible intensive
interactions are given in Table 5. The second-order perturbation
theory analysis of Fock matrix in NBO basis shows strong intramo-
lecular hyper-conjugative interactions of p-electrons. The intramo-
lecular hyper-conjugative interactions are formed by the orbital
overlap between n(Cl and p⁄(CAC) bond orbital which results in
ICT causing stabilization of the system. The strong intramolecular
hyper-conjugative interaction of C10AC12 from Cl1 of n3(Cl1) ? p⁄(-
First hyperpolarizability
The nonlinear optical activity provides the key functions for fre-
quency shifting, optical modulation, optical switching and optical
C10AC12) which increases ED (0.37434e) that weakens the respec-

C.S. Chidan Kumar et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 126 (2014) 208–219
215
Table 5
Second order perturbation theory analysis of Fock matrix in NBO basis corresponding to the intramolecular bonds of the title compound.
Donor (i)
Type
ED/e
Acceptor (j)
Type
ED/e
E(2)a
E(j) ꢁ E(i)b
F(i, j)c
Cl1AC12
–
O2AC18
O2AC18
O3AC19
–
O3AC22
–
O4AC22
–
O4AC22
O5AN7
O6AN7
O6AN7
–
r
r
r
p
r
r
r
r
r
r
p
1.98256
–
1.99182
1.96676
1.98654
–
1.98534
–
1.99163
–
1.97880
1.99129
1.99137
1.98331
–
C8AC10
C13AC15
C8AC17
r⁄
r⁄
r⁄
p⁄
r⁄
r⁄
r⁄
r⁄
r⁄
r⁄
p⁄
r⁄
r⁄
p⁄
p⁄
r⁄
r⁄
r⁄
r⁄
r⁄
r⁄
r⁄
r⁄
p⁄
p⁄
p⁄
r⁄
r⁄
p⁄
p⁄
r⁄
r⁄
r⁄
r⁄
r⁄
p⁄
p⁄
r⁄
r⁄
r⁄
r⁄
r⁄
r⁄
r⁄
r⁄
r⁄
r⁄
r⁄
r⁄
r⁄
r⁄
p⁄
p⁄
p⁄
r⁄
r⁄
p⁄
p⁄
r⁄
r⁄
r⁄
r⁄
p⁄
p⁄
p⁄
r⁄
r⁄
r⁄
r⁄
r⁄
r⁄
r⁄
p⁄
r⁄
r⁄
0.04256
0.01479
0.02395
0.38459
0.06140
0.06154
0.06602
0.02183
0.06154
0.02334
0.02183
0.02148
0.02322
0.65474
0.37714
0.02183
0.01514
0.04256
0.02395
0.06140
0.00926
0.01573
0.02382
0.14532
0.37434
0.27491
0.01573
0.02866
0.38459
0.27491
0.02820
0.01479
0.04256
0.02866
0.06140
0.38459
0.37434
0.02395
0.06602
0.01573
0.01479
0.10326
0.02382
0.02557
0.01533
0.02148
0.01799
0.02183
0.10326
0.10341
0.02334
0.26267
0.28025
0.37714
0.06154
0.02334
0.33608
0.37714
0.10341
0.02322
0.05900
0.02148
0.65474
0.33608
0.28025
0.05972
0.06154
0.02322
0.02820
0.02866
0.02820
0.02866
0.37434
0.06140
0.06602
3.79
1.21
1.22
1.55
0.39
1.22
1.22
1.23
1.42
1.45
1.56
0.40
1.53
1.52
0.28
0.44
1.34
1.34
0.77
1.22
1.11
1.20
1.23
1.22
0.25
0.27
0.29
1.26
1.25
0.29
0.30
1.25
1.27
0.77
1.22
1.11
0.28
0.27
1.21
1.03
1.20
1.21
0.93
1.17
0.90
1.21
1.20
1.19
1.23
0.99
0.95
1.22
0.24
0.29
0.27
1.10
1.22
0.28
0.27
0.95
1.21
1.02
1.24
0.12
0.29
0.30
1.02
1.12
1.23
1.45
1.45
0.83
0.83
0.32
1.09
1.02
0.061
0.060
0.053
0.048
0.046
0.053
0.038
0.054
0.040
0.051
0.039
0.040
0.040
0.052
0.045
0.049
0.048
0.059
0.044
0.063
0.046
0.043
0.051
0.069
0.068
0.070
0.041
0.048
0.071
0.067
0.048
0.040
0.060
0.046
0.060
0.067
0.072
0.051
0.049
0.056
0.057
0.049
0.058
0.058
0.053
0.059
0.051
0.028
0.045
0.065
0.052
0.072
0.074
0.066
0.064
0.027
0.065
0.076
0.065
0.041
0.049
0.057
0.063
0.076
0.063
0.049
0.061
0.057
0.049
0.049
0.050
0.050
0.056
0.054
0.040
3.69
2.28
6.07
2.15
2.84
1.42
2.58
1.37
2.09
4.05
1.33
1.33
8.39
4.79
2.29
2.13
5.69
2.02
4.42
2.20
1.86
2.69
21.52
21.45
20.50
1.69
2.30
20.75
18.22
2.30
1.61
5.76
2.17
3.96
20.24
24.54
2.72
2.88
3.23
3.40
3.12
3.62
4.70
2.93
3.62
2.71
2.79
2.49
5.40
2.74
25.79
22.55
19.97
4.58
1.67
18.87
27.04
5.28
1.74
2.87
3.32
36.08
24.36
15.92
2.88
4.14
3.27
2.04
2.05
3.78
3.77
10.69
3.26
1.88
C8AC17
C17AC18
C22AC23
C18AC19
C23AC31
C22AC23
C23AC24
C23AC31
C30AC31
C28AC30
O6AN7
C28AC30
C23AC31
C26AC28
Cl1AC12
C8AC17
C17AC18
O2AC18
C8AC10
C15AC17
O2AC18
C10AC12
C13AC15
C8AC10
r
r
p
p
N7AC30
–
C8AC10
–
r
r
r
r
r
r
r
r
p
p
p
r
r
p
1.98669
–
1.97020
–
–
–
C8AC17
–
–
C8AC17
–
–
C10AC12
–
C10AC12
–
C12AC13
–
C13AC15
–
1.97674
–
–
1.63904
–
–
1.98246
–
1.66002
–
1.98282
–
1.97033
–
C12AC13
C8AC17
p
C13AC15
C10AC12
C13AC15
Cl1AC12
C12AC13
C17AC18
C8AC17
C10AC12
C8AC17
C18AC19
C8AC10
C13AC15
O3AC22
C15AC17
O3AC19
C24AC26
C30AC31
O4AC22
C23AC31
O3AC22
N7AC30
C23AC24
O4AC22
C24AC26
C28AC30
C22AC23
C23AC24
C23AC31
C28AC30
N7AC30
C28AC30
O6AN7
C30AC31
O6AN7
C23AC31
C24AC26
O5AN7
C22AC23
C28AC30
C10AC12
C12AC13
C10AC12
C12AC13
C10AC12
C17AC18
C18AC19
r
r
r
r
r
p
–
–
C13AC15
–
C15AC17
–
C17AC18
–
C18AC19
–
C22AC23
–
–
C23AC24
–
C23AC31
–
1.64081
–
1.97307
–
1.97449
–
1.97980
–
1.96708
–
–
1.97671
–
1.96881
–
p
r
r
r
r
r
r
r
r
r
r
r
r
r
r
p
–
–
C23AC31
–
–
C24AC26
–
C24AC26
–
C26AC28
–
C28AC30
–
C28AC30
–
–
C30AC31
–
–
LPCl1
–
LPCl1
–
LPCl1
LPO2
–
1.61672
–
–
1.97980
–
1.60994
–
1.97644
–
1.97603
–
1.62163
–
–
1.97412
–
–
1.98983
–
1.97665
–
1.93021
1.97679
–
p
p
r
r
p
p
r
r
r
r
p
p
p
r
r
r
r
r
p
p
n
r
r
(continued on next page)

216
C.S. Chidan Kumar et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 126 (2014) 208–219
Table 5 (continued)
Donor (i)
Type
ED/e
Acceptor (j)
Type
ED/e
E(2)a
15.94
20.71
6.81
44.92
3.59
32.43
15.67
2.24
E(j) ꢁ E(i)b
F(i, j)c
LPO2
–
p
p
r
p
r
p
p
r
r
p
p
n
1.89899
–
C17AC18
C18AC19
O4AC22
O4AC22
C22AC23
O3AC22
C22AC23
O6AN7
N7AO30
O6AN7
N7AC30
O6AN7
r⁄
r⁄
r⁄
p⁄
0.06140
0.06602
0.01799
0.26267
0.06154
0.10326
0.06154
0.05900
0.10341
0.05900
0.10341
0.65474
0.05972
0.10341
0.05972
0.10341
0.67
0.61
1.05
0.30
1.10
0.56
0.67
1.11
1.06
0.59
0.53
0.11
1.11
1.06
0.59
0.53
0.093
0.101
0.076
0.106
0.057
0.121
0.094
0.045
0.068
0.093
0.067
0.125
0.045
0.068
0.093
0.067
LPO3
LPO3
LPO4
LPO4
–
LPO5
–
LPO5
–
LPO5
LPO6
–
LPO6
–
1.96676
1.80152
1.97575
1.86271
–
1.97776
–
1.91246
–
1.43586
1.97759
–
1.91158
–
r⁄
r⁄
r⁄
r⁄
r⁄
r⁄
r⁄
p⁄
5.31
18.05
10.39
167.09
2.26
5.33
18.22
10.61
r
r
p
p
O5AN7
N7AC30
O5AN7
r⁄
r⁄
r⁄
r⁄
N7AC30
a
E(2) means energy of hyper-conjugative interactions (stabilization energy in kcal molꢁ1).
Energy difference between donor and acceptor i and j NBO orbitals in a.u.
F(i, j) is the Fock matrix elements between i and j NBO orbitals in a.u.
b
c
logic for the developing technologies in areas such as communica-
title compound, the HOMO of p nature is delocalized over the
tion, signal processing and optical interconnections [47,48]. The
first static hyperpolarizablity (b0) is calculated at the DFT level
based on the finite field approach. In the presence of an applied
electric field, the energy of a system is a function of the electric
field and the first hyperpolarizability is a third rank tensor than
can be described by 3 ꢃ 3 ꢃ 3 matrix. The 27 components of the
3D matrix can be given in the lower tetrahedral format and re-
duced to 10 components because of Kleinman symmetry [49].
The components of b0 are defined as the coefficients in the Taylor
series expansion of the energy in the external electric field. When
the external electric field is weak and homogeneous, this expan-
sion is given below:
whole CAC bonds of the para substituted phenyl ring. Accordingly,
the HOMO–LUMO transition implies an electron density transfer
from the para substituted phenyl ring to the 1,3-substituted phenyl
ring through the oxoethyl group. For understanding various as-
pects of pharmacological sciences including drug design and the
possible ecotoxicological characteristics of the drug molecules,
several new chemical reactivity descriptors have been proposed.
Conceptual DFT based descriptors have helped in many ways to
understand the structure of the molecules and their reactivity by
calculating the chemical potential, global hardness and electrophi-
licity. Using HOMO and LUMO orbital energies, the ionization en-
ergy and electron affinity can be expressed as: I = ꢁEHOMO
A = ꢁELUMO = (ꢁEHOMO + ELUMO)/2 and = (EHOMO + ELUMO)/2
[57]. Parr et al. [58] proposed the global electrophilicity power of
a ligand as . This index measures the stabilization in en-
2/2
,
,
g
l
X
X
X
X
1
2
1
6
1
24
E ¼ E0 ꢁ
l
iFi ꢁ
a
ijFiFj ꢁ
bijkFiFjFk ꢁ
c
ijklFiFjFkFl
i
ij
ijk
ijkl
x
=
l
g
ergy when the system acquired an additional electronic charge
from the environment. Electrophilicity encompasses both the abil-
ity of an electrophile to acquire additional electronic charge and
the resistance of the system to exchange electronic charge with
the environment. It contains information about both electron
transfer (chemical potential) and stability (hardness) and is a bet-
þ ꢂ ꢂ ꢂ
where E0 is the energy of the unperturbed molecule, Fi is the field at
the origin, li i, bijk and ijkl are the components of dipole moment,
,
a
c
polarizability, the first hyperpolarizabilities and second hyperpolar-
izabilities, respectively. The calculated first hyperpolarizability of
the title compound is 3.4 ꢃ 10ꢁ30 e.s.u., and is 2.62 times that of
the standard NLO material urea (0.13 ꢃ 10ꢁ30 e.s.u.) [50]. We con-
clude that the title compound is an attractive object for future stud-
ies of nonlinear optical properties.
ter descriptor of global chemical reactivity. The hardness
chemical potential are given by the following relations:
=(IꢁA)/2 and
g and
l
g
l
= ꢁ(I + A)/2, where I and A are the first ionization
potential and electron affinity of the chemical species [59]. For the
title compound, EHOMO = ꢁ8.19 eV, ELUMO = ꢁ5.24 eV, energy
gap = EHOMO ꢁ ELUMO = 2.95 eV, ionization potential I = 8.19 eV,
Frontier molecular orbitals
electron affinity A = 5.24 eV, global hardness
g
= 1.48 eV, chemical
potential
l
= ꢁ6.72 eV
and
global electrophilicity =
To explain several types of reaction and for predicting the most
reactive position in conjugated systems, molecular orbitals and
their properties such as energy are used [51]. The highest occupied
molecular orbital (HOMO) and lowest unoccupied molecular orbi-
tal (LUMO) are the most important orbitals in a molecule. The ei-
gen values of HOMO and LUMO and their energy gap reflect the
biological activity of the molecule. A molecule having a small fron-
tier orbitals gap is more polarizable and is generally associated
with a high chemical reactivity and low kinetic stability [52–54].
HOMO which can be though as the outer orbital containing elec-
trons, tend to give these electrons as an electron donor and hence
the ionization potential is directly related to the energy of the
HOMO. On the other hand LUMO can accept electrons and the
LUMO energy is directly related to electron affinity [55,56]. Two
important molecular orbitals were examined for the title com-
pound, HOMO and LUMO which are given in Figs. 5 and 6. In the
l
2/2
g = 15.26 eV. It is seen that the chemical potential of the title
compound is negative and it means that the compound is stable.
They do not decompose spontaneously into the elements they
are made up of. The hardness signifies the resistance towards the
deformation of electron cloud of chemical systems under small
perturbation encountered during the chemical process. The princi-
ple of hardness works in Chemistry and physics but it is not phys-
ically observable. Soft systems are large and highly polarizable,
while hard systems are relatively small and much less polarizable.
Molecular electrostatic potential
Molecular electrostatic potential (MEP) generally presents in
the space around the molecule by the charge distribution is very
useful in understanding the sites of electrophilic attacks and nucle-

C.S. Chidan Kumar et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 126 (2014) 208–219
217
Table 6
NBO results showing the formation of Lewis and non-Lewis orbitals.
Table 6 (continued)
Bond(AAB) ED/energy EDA% EDB% NBO
s%
–
p%
–
Bond(AAB) ED/energy EDA% EDB% NBO
s%
p%
–
ꢁ0.29058
1.96676
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
57.20 42.80 0.7563(sp5.41)Cl
15.60 84.40
n1O3
–
n2O3
–
n1O4
–
n2O4
–
n1O5
–
n2O5
–
n3O5
–
n1O6
–
sp1.34
–
42.67 57.33
–
0.00
–
63.77 36.23
–
0.00
–
80.45 19.55
–
0.19
–
0.00
–
80.42 19.58
–
r
–
r
–
Cl1AC12
O2AC18
1.98526
ꢁ0.70579
1.99182
–
–
+0.6542(sp3.79)C 20.87 79.13
ꢁ0.58895
–
66.23 33.77 0.8138(sp1.65)O
37.76 62.24
1.80152
sp1.00
–
100.0
–
ꢁ1.06056
–
–
+0.5811(sp2.22)C 31.09 68.91
ꢁ0.35390
1.97575
65.56 34.44 0.8097(sp1.00)O
+0.5869(sp1.00)C 0.00
69.05 30.95 0.8310(sp2.63)O
0.00
100.0
100.0
sp0.57
–
pO2AC18
1.96676
–
r
–
r
–
r
–
ꢁ0.39489
1.98654
–
–
ꢁ0.72047
–
1.86271
sp1.00
–
100.0
–
O3AC19
O3AC22
O4AC22
27.58 72.42
+0.5563(sp4.07)C 19.71 80.29
69.58 30.42 0.8341(sp2.36)O
29.75 70.25
+0.5516(sp2.71)C 26.95 73.05
66.05 33.95 0.8127(sp1.76)O
36.26 63.74
+0.5826(sp1.95)C 33.85 66.15
ꢁ0.83913
–
–
ꢁ0.29782
1.97776
sp0.24
–
1.98534
ꢁ0.91760
1.99163
–
–
ꢁ0.83453
–
1.91246
sp99.99
–
99.81
–
100.0
–
ꢁ1.07089
–
–
ꢁ0.31340
1.43586
68.89 31.11 0.8300(sp1.00)O
+0.5578(sp1.00)C 0.00
50.60 49.40 0.7114(sp4.15)O
0.00
100.0
100.0
sp1.00
–
pO4AC22
1.97880
–
r
–
r
–
ꢁ0.40740
1.99129
–
–
ꢁ0.29521
1.97759
sp0.24
–
O5AN7
O6AN7
19.42 80.58
+0.7028(sp2.20)N 31.30 68.70
50.60 49.40 0.7113(sp4.14)O
19.47 80.53
+0.7029(sp2.19)N 31.38 68.52
ꢁ1.03646
–
–
ꢁ0.83401
1.91158
ꢁ0.31288
–
n2O6
–
sp99.99
–
0.18
–
99.82
–
1.99137
ꢁ1.03860
1.98331
–
–
pO6AN7
58.33 41.67 0.7637(sp1.00)O
+0.6456(sp1.00)N 0.00
63.37 36.63 0.7960(sp1.70)N
0.00
100.0
100.0
ED/energy is expressed in a.u.
–
r
–
r
–
r
–
ꢁ0.45944
–
–
N7AC30
C8AC10
C8AC17
1.98669
37.04 62.96
+0.6052(sp3.16)C 24.04 75.96
50.04 49.96 0.7074(sp1.82)C
35.43 64.57
+0.7068(sp1.80)C 35.75 64.25
49.49 50.51 0.7035(sp1.80)C
35.73 64.27
+0.7107(sp1.86)C 34.92 65.08
ꢁ0.83728
1.97020
–
–
ꢁ0.72715
–
–
1.97674
ꢁ0.72644
1.63904
–
–
pC8AC17
46.83 53.17 0.6844(sp1.00)C
+0.7292(sp1.00)C 0.00
49.56 50.44 0.7040(sp1.86)C
0.00
100.0
100.0
ꢁ0.28692
–
–
r
–
C10AC12
1.98246
34.91 65.09
ꢁ0.75461
1.66002
–
–
+0.7102(sp1.53)C 39.53 60.47
pC10AC12
48.03 51.97 0.6930(sp1.00)C
+0.7209(sp1.00)C 0.00
50.58 49.42 0.7112(sp1.53)C
0.00
100.0
100.0
–
r
–
r
–
ꢁ0.30124
–
–
C12AC13
C13AC15
1.98282
39.55 60.45
+0.7030(sp1.88)C 34.76 65.24
50.32 49.68 0.7094(sp1.79)C
35.82 64.18
+0.7048(sp1.83)C 35.39 64.61
ꢁ0.75258
1.97033
–
–
ꢁ0.72439
–
–
pC13AC15
1.64081
52.02 47.80 0.7225(sp1.00)C
+0.6914(sp1.00)C 0.00
49.06 50.94 0.7004(sp1.85)C
0.00
100.0
100.0
Fig. 5. HOMO plot of 2-(4-chlorophenyl)-2-oxoethyl 3-nitrobenzoate.
–
r
–
r
–
r
–
r
–
r
–
r
–
ꢁ0.28248
1.97307
–
–
C15AC17
C17AC18
C18AC19
C22AC23
C23AC24
C23AC31
35.13 64.87
+0.7137(sp1.92)C 34.20 65.80
51.68 48.32 0.7189(sp2.24)C
30.87 69.13
+0.6951(sp1.76)C 36.26 63.74
48.17 51.83 0.6941(sp2.05)C
32.77 67.23
+0.7199(sp2.47)C 28.81 71.29
48.40 51.60 0.6957(sp1.54)C
39.35 60.65
+0.7183(sp2.35)C 29.86 70.14
51.19 48.81 0.7154(sp1.82)C
35.50 64.50
+0.6987(sp1.89)C 34.65 65.35
50.42 49.58 0.7101(sp1.89)C
34.60 65.40
+0.7041(sp1.83)C 35.35 64.65
ꢁ0.71603
–
–
1.97449
ꢁ0.69046
1.97980
–
–
ꢁ0.67403
–
–
1.96708
ꢁ0.70603
1.97671
–
–
ꢁ0.72885
–
–
1.96881
ꢁ0.73147
1.61672
–
–
pC23AC31
55.86 44.14 07474(sp1.00)C0. 0.00
+0.6644(sp1.00)C 0.00
50.19 49.81 0.7085(sp1.83)C
100.0
100.0
–
r
–
ꢁ0.29049
–
–
C24AC26
1.97980
35.36 64.64
+0.7057(sp1.82)C 35.43 64.57
Fig. 6. LUMO plot of 2-(4-chlorophenyl)-2-oxoethyl 3-nitrobenzoate.
ꢁ0.72761
1.60994
–
–
pC24AC26
46.80 53.20 0.6841(sp1.00)C
+0.7294(sp1.00)C 0.00
49.40 50.60 0.7028(sp1.85)C
0.00
100.0
100.0
–
r
–
r
–
ꢁ0.28510
–
–
C26AC28
C28AC30
1.97644
35.04 64.96
+0.7113(sp1.79)C 35.80 64.20
48.99 51.01 0.6999(sp1.93)C
34.11 65.89
+0.7142(sp1.65)C 37.79 62.21
ꢁ0.73086
1.97603
–
–
ꢁ0.74570
–
–
pC28AC30
1.62163
43.88 56.12 0.6624(sp1.00)C
+0.7491(sp1.00)C 0.00
50.69 49.31 0.7119(sp1.63)C
38.05 61.95
0.00
100.0
100.0
–
r
–
ꢁ0.30140
1.97412
–
–
C30AC31
ꢁ0.74860
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
+0.7022(sp1.91)C 34.38 65.62
n1Cl1
–
n2Cl1
–
n3Cl1
–
n1O2
–
1.98983
sp0.18
–
84.40 15.60
–
0.00
–
0.00
–
62.16 37.84
–
0.11
ꢁ0.95238
1.97665
–
sp1.00
–
100.0
–
100.0
–
ꢁ0.33396
1.93021
sp1.00
–
ꢁ0.33208
1.97679
sp0.61
–
ꢁ0.70762
–
n2O2
1.89899
sp99.99
99.89
Fig. 7. MEP plot of 2-(4-chlorophenyl)-2-oxoethyl 3-nitrobenzoate.

218
C.S. Chidan Kumar et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 126 (2014) 208–219
ophilic reaction for the study of biological recognition process [60]
and hydrogen bonding interactions [61]. In order to predict the
molecular reactive sites, the MEP for the title compound is calcu-
lated at B3LYP method as shown in Fig. 7. The different values of
the electrostatic potential at the surface are represented by differ-
ent colors. Potential increases in the order red < orange <
yellow < green < blue where blue indicates the highest electro-
static potential energy and red indicates the lowest electrostatic
potential energy. Intermediary colors represent intermediary elec-
trostatic potentials. As it can be seen from the MEP map of the title
compound, both the carbonyl groups have the lowest value of elec-
trostatic potential energy whereas the nitrogen has the highest
electrostatic potential energy.
was confirmed by IR and single-crystal X-ray diffraction studies.
The vibrational wavenumbers were examined theoretically using
the Gaussian09 set of quantum chemistry codes, and the normal
modes were assigned by potential energy distribution calculation.
The geometrical parameters of the title compound are in agree-
ment with XRD results. A computation of the first hyperpolariz-
ability indicates that the compound may be a good candidate as
a NLO material. Stability of the molecule arising from hyper-
conjugative interaction and charge delocalization has been
analyzed using NBO analysis. The calculated HOMO and LUMO
energies show the chemical activity of the molecule.
Acknowledgements
CSC thanks Universiti Sains Malaysia for a postdoctoral research
fellowship. CKQ thanks USM for APEX DE2012 Grant (No. 1002/PFI-
ZIK/910323). The authors extend their appreciation to The
Deanship of Scientific Research at King Saud University for the
research group Project No. RGP VPP-207. The authors would like
to thank Dr. Hema Tresa Varghese, FMN College, Kollam, Kerala,
India for providing computational facility.
Geometrical parameters
The aromatic rings of the title compound are somewhat irregu-
lar and the spread of the CC bond distance is 1.4009–1.4136 Å
(DFT), 1.3474–1.3893 Å (XRD) for ring I and 1.4020–1.4155 Å
(DFT), 1.3773–1.4013 Å (XRD) for ring II which is similar to the
spread reported by Smith et al., [62]. For the title compound, the
CAN bond length is 1.4799 Å (DFT), 1.4843 Å (XRD) and NO bond
lengths are 1.2792, 1.2777 (DFT), 1.2114, 1.2124 Å (XRD), which
are in agreement with the reported values. Chambers et al. [63] re-
ported NO bond lengths in the range 1.2201–1.2441 Å and CAN
bond length as 1.4544 Å. The experimental values of NO bond
lengths are 1.222–1.226 Å and CAN lengths in the range 1.442–
1.460 [64]. Sundaraganesan et al. [25] reported CAN bond lengths
as 1.453, 1.46 Å (DFT) and NO bond lengths in the range 1.228–
1.248 Å. The CNO angles are reported in the [25] range 117.4–
118.7 where as for the title compound, the range is 117.9–118.2°
(DFT), 118.5–118.6° (XRD). The CACl bond length 1.8170 Å (DFT),
1.7332 Å (XRD) is in agreement with the CACl bond length given
by Mariamma et al. [65]. Chlorine is highly electronegative and
tries to obtain additional electron density. It attempts to draw it
from the neighboring atoms which moves closer together in order
to share the electrons more easily as a result. Due to this the bond
angle C10AC12AC13 is found to be 122.0° in the present calculation,
which is 120° for normal benzene. According to our calculations, at
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