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Spectrochimica Acta Part A 79 (2011) 962969

Contents lists available at ScienceDirect

Spectrochimica Acta Part A: Molecular andBiomolecular Spectroscopy

j ournal homepage: www.elsevier .com/locate /saa

FT-IR and FT-Raman, vibrational assignments, molecular geometry, ab initio (HF)

and DFT (B3LYP) calculations for 1,3-dichlorobenzene

D. Mahadevana,, S. Periandyb, S. Ramalingamc

a Department ofPhysics, Govt. ArtsCollege, Tindivanam, Tamilnadu, Indiab Department ofPhysics, TagoreArts college, Puducherry, Indiac Department ofPhysics, A.V.C. College, Mayiladuthurai, Tamilnadu, India

a r t i c l e i n f o

Article history:

Received 1 February 2011

Received in revised form 23 March 2011

Accepted 4 April 2011

Keywords:

1,3-Dichlorobenzene

Inductive effect

Ab initio HartreeFock

B3LYP

FT-IR

FT-Raman

a b s t r a c t

The FT-IR and FT-Raman vibrational spectra of1,3-dichlorobenzene (1,3-DCB) have been recorded using

Bruker IFS 66 V Spectrometer in the range 4000100 cm1. A detailed vibrational spectral analysis has

been carried out and assignments ofthe observed fundamental bands have been proposed on the basis

of peak positions and relative intensities. The optimized molecular geometry, vibrational frequencies,

atomic charges, dipole moment, rotational constants and several thermodynamic parameters in the

ground state were calculated using ab initio HartreeFock (HF) and DFT (B3LYP) methods with 6-31++G

(d, p) and 6-311++G (d, p) basis sets. With the help ofdifferent scaling factors, the observed vibrational

wave numbers in FT-IR and FT-Raman spectra were analyzed and assigned to different normal modes

of the molecule. Most of the modes have wave numbers in the expected range. The inductive effect of

Chlorine atoms in the benzene molecule has also been investigated.

2011 Elsevier B.V. All rights reserved.

1. Introduction

Benzene is mainlyused as an intermediate to make other chem-

icals. Its most widely-produced derivatives include styrene, which

is used to make polymers and plastics, phenol for resins and adhe-

sives, and cyclohexane, which is used in the manufacture ofNylon

[1]. Benzene is a clear, colorless, no corrosive and highly flammable

liquid with a sweet odor. It evaporates into the air very quickly and

dissolves slightly in water [2]. Someindustries use benzene to make

plastics,resins, andNylonand syntheticfibers. Benzene is also used

to make some types ofrubbers, lubricants, dyes, detergents, drugs,

and pesticides. Natural sources ofbenzene include volcanoes and

forest fires. Benzene is also a natural part ofcrude oil, gasoline, and

cigarette smoke [3,4].

Chlorobenzene once was used for manufacturing of certain

pesticides, most notably DDT by reaction with chloral (trichloroac-

etaldehyde), but this application has declined with the diminished

use of DDT. At one time, chlorobenzene was the main precursor

for the manufacture of phenol [5]. The major use of chloroben-

zene is as an intermediate in the production ofcommodities such

as herbicides, dyestuffs, and rubber. Chlorobenzene is also used

as a high-boiling solvent in many industrial applications as well

as in the laboratory [6]. Other applications include use as a fiber

Correspondingauthor. Tel.: +91 9976306898; fax: +91 9976306898.

E-mail address: [email protected] (D. Mahadevan).

swelling agent and dye carrier in textile processing, as a tar andgrease remover in cleaning and degreasing operations, as a sol-

vent in surface coating and surface coating removers, and as a

heat-transfer medium. Chlorobenzene is nitrated on a large scale

to give a mixture of 2- and 4-nitrochlorobenzenes, which can

be separated by fractional crystallization followed by distillation.

2-Nitrochlorobenzene is converted to related 2-nitrophenol, 2-

nitroanisole, bis(2-nitrophenyl)disulfide, and 2-nitropaniline by

nucleophilic displacement ofthe chloride with sodium hydroxide,

sodium methoxide, sodium disulfide and ammonia. The conver-

sion ofthe 4-nitrochlorobenzene is similar [7]. Dichlorobenzene

belong to the group oforganic halogen compounds replacing two

hydrogen atoms in benzene by chlorine atoms. 1,3-DCB used in the

fumigant and insecticide, solvent, chemical intermediate to man-

ufacture dyes, agrochemicals, pharmaceuticals and other organic

synthesis (Fig. 1).

In the present work, we have studied the FT-IR and FT-

Raman spectra of 1,3-DCB. The comparative IR and Raman

spectra of experimental and calculated DFT (B3LYP) are given

in Figs. 2 and 3 respectively. The ab initio HF and DFT cal-

culations are performed to obtain the ground state optimized

geometries and the vibrational wavenumbers ofthe different nor-

mal modes as well as to predict the corresponding intensities

for the different modes ofthe molecule. In DFT methods, Beckes

three parameter exact exchange-functional (B3) [8,9] combined

with gradient-corrected correlational functional of Lee, Yang and

Parr (LYP) [10,11] are the best predicting results for molecular

1386-1425/$ see front matter 2011 Elsevier B.V. All rights reserved.

doi:10.1016/j.saa.2011.04.003
http://dx.doi.org/10.1016/j.saa.2011.04.003http://dx.doi.org/10.1016/j.saa.2011.04.003http://dx.doi.org/10.1016/j.saa.2011.04.003http://www.sciencedirect.com/science/journal/13861425http://www.elsevier.com/locate/saamailto:[email protected]://dx.doi.org/10.1016/j.saa.2011.04.003http://dx.doi.org/10.1016/j.saa.2011.04.003mailto:[email protected]://www.elsevier.com/locate/saahttp://www.sciencedirect.com/science/journal/13861425http://dx.doi.org/10.1016/j.saa.2011.04.003

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D. Mahadevan et al. / Spectrochimica Acta Part A 79 (2011) 962969 963

Fig. 1. Molecular structure of1,3-dichlorobenzene.

geometry and vibrational wave numbers for moderately largermolecule.

2. Experimental details

The spectroscopic grade 1,3-DCB was purchased from Sigma

Aldrich Chemicals, U.S.A. and used as such for recording spectra

without further purification. The FT-IR spectrum ofthe title com-

pound was recorded using Bruker IFS 66 V spectrometer in the

range of4000100 cm1. The spectral resolution is 2 cm1. The

FT-Raman spectrum of 1,3-DCB was also recorded in the same

instrument with FRA 106 Raman module equipped with Nd:YAG

laser source operating at 1.064m with 200 Mw power. Boththe spectra were recorded in the range of4000100 cm1 with

scanning speed of30 cm1 min1 of spectral width 2 cm1. Thefrequencies ofall sharp bands are accurate to 1 cm1.

Fig. 2. (A) Experimental, (B) calculated, (C and D) FTIR s pectr a of 1,3-

dichlorobenzene.

Fig. 3. (A) Experimental, (B) calcu late d, ( C and D) FT-Raman spectra of 1,3-

dichlorobenzene.

3. Computationalmethods

Many studies [1214] have shown that the DFT-B3LYP method

in combination with the 6-31++G (d, p) and 6-311++G (d, p) basis

sets are able to give the accurate energies, molecularstructures, and

infrared vibrational frequencies. The molecularstructure ofthe 1,3-

DCB in the ground state is computed by performing both ab initio

(HF) with 6-311++G(d, p) and DFT (B3LYP) with 6-31++G (d, p) and

6-311++G (d, p) basis sets. The optimized structural parameters

are used in the vibrational frequency calculations at HF and DFT

levels. The minimum energy ofgeometrical structure is obtainedusinglevel 6-311++G(d, p) basis sets.The calculatedfrequencies are

scaled by 0.914, 0.87, 0.99 and 1.07 for HF/6-311++G (d, p) [15,16].

For B3LYP with 6-31++G (d, p) set is scaled 0.955, 0.93, 1.01, 0.99,

and 1.07 and B3LYP/6-311++G (d, p) basis set is scaled with 0.96,

0.947, 1.01, 1.07 and 0.99 [17]. HF/DFT calculations for 1,3-DCB are

performed using GAUSSIAN 03W program package on Pentium IV

processor personal computer without any constraint on the geom-

etry [18,19]. The comparative values ofIR intensities and Raman

activities are presented in Table 3 and their corresponding graph

given in Figs. 4 and5.

4. Results and discussion

4.1. Molecular geometry

The molecularstructure ofthe 1,3-DCB belongs to CS point group

symmetry and its molecular structure is obtained from GAUSSAN

03 W and GAUSSVIEW programs are shown in Fig. 1. The molecule

contains two Chlorine atoms with benzene ring. The compara-

tive optimized structural parameters such as bond lengths, bond

angles and dihedral angles are presented in Table 1. The compar-

ative graphs ofbond lengths, bond angles and dihedral angles of

1,3-DCB for three sets are presented in Figs. 68 respectively. From

the theoretical values, it is found that most ofthe optimized bond

lengths are slightly larger than the experimental values, due to that

the theoretical calculations belong to isolated molecules in gaseous

phase and the experimental results belong to molecules in solid

state. Comparing bond angles and lengths ofB3LYP with those of
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964 D. Mahadevan et al./ Spectrochimica Acta Part A 79 (2011) 962969

Table 1

Optimized geometrical parameters for 1,3-dichlorobenzene computed at HF/6-311++ (d, p), B3LYP/6-31++G (d, p) and6-311++G (d, p) basis sets.

Geometrical parameters Methods

HF/6-311++G (d, p) B3LYP/6-31++G(d, p) B3LYP/6-311++(d, p) Experimental Values

Bond length(A)

C1C2 1.382 1.395 1.392

C1C6 1.381 1.395 1.381

C1Cl11 1.741 1.756 1.741 1.744

C2C3 1.382 1.395 1.382

C2H7 1.071 1.083 1.071 1.090

C3C4 1.381 1.395 1.381

C3Cl12 1.741 1.756 1.741 1.744

C4C5 1.384 1.396 1.384

C4H8 1.072 1.083 1.072 1.090

C5C6 1.384 1.396 1.384

C5H9 1.074 1.085 1.074 1.090

C6H10 1.072 1.083 1.072 1.090

Bond angle ()

C2C1C6 121.5 121.6 121.5

C2C1Cl11 118.9 118.8 118.9

C6C1Cl11 119.4 119.4 119.4

C1C2C3 118.3 118.1 118.3

C1C2H7 120.8 120.9 120.8

C3C2H7 120.8 120.9 120.8

C2C3C4 121.5 121.6 121.5

C2C3Cl12 118.9 118.8 118.9

C4C3Cl12 119.4 119.4 119.4 C3C4C5 118.8 118.7 118.8

C3C4H8 120.2 120.2 120.2

C5C4H8 120.9 121.0 120.9

C4C5C6 120.8 121.0 120.8

C4C5H9 119.5 119.4 119.5

C6C5H9 119.5 119.4 119.5

C1C6C5 118.8 118.7 118.8

C1C6H10 120.2 120.2 120.2

C5C6H10 120.9 121.0 120.9

Dihedral angles()

C6C1C2C3 0.0 0.0 0.0

C6C1C2H7 180.0 180.0 180.0

Cl11C1C2C3 180.0 180.0 180.0

Cl11C1C2H7 0.0 0.0 0.0

C2C1C6C5 0.0 0.0 0.0

C2C1C6H10 180.0 180.0 180.0

Cl11C1C6C5 180.0 180.0 180.0 Cl11C1C6H10 0.0 0.0 0.0

C1C2C3C4 0.0 0.0 0.0

C1C2C3Cl12 180.0 180.0 180.0

H7C2C3C4 180.0 180.0 180.0

H7C2C3Cl12 0.0 0.0 0.0

C2C3C4C5 0.0 0.0 0.0

C2C3C4H8 180.0 180.0 180.0

Cl12C3C4C5 180.0 180.0 180.0

Cl12C3C4H8 0.0 0.0 0.0

C3C4C5C6 0.0 0.0 0.0

C3C4C5H9 180.0 180.0 180.0

H8C4C5C6 180.0 180.0 180.0

H8C4C5H9 0.0 0.0 0.0

C4C5C6C1 0.0 0.0 0.0

C4C5C6H10 180.0 180.0 180.0

H9C5C6C1 180.0 180.0 180.0

H9C5C6H10 0.0 0.0 0.0

HF, as a whole the formers are bigger than later and the B3LYP

calculated values correlates well compared with the experimental

data. Although the differences, calculated geometrical parameters

represent a good approximation and they are the bases for the

calculating other parameters, such as vibrational frequencies and

thermodynamics properties.

From the data shown in Table 1, it is seen that both HF and DFT

(B3LYP/6-311++G (d, p)) levels oftheory in general estimate same

values ofsome bond lengths and bond angles. The perfect hexago-

nal structure ofbenzene is slightly distorted by the substitution of

couple ofCl atoms and is evident by the order ofCC bond length

ofthe ring as C3C4 = C6C1

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Table 2

Observed and HF/6-311++G (d, p), B3LYP/6-31++G (d, p) and B3LYP/6-311++G (d, p) level calculated vibrational frequencies of1,3-dichlorobenzene.

S.No. Symmetry

species CS

Observed

frequency

Calculated frequency

(cm1) with

HF/6-311++G (d, p)


(cm1) with

B3LYP/6-31++G (d, p)


(cm1) with

B3LYP/6-311++G (d, p)

Vibrational

assignments

FTIR FT-Raman Unscaled

value

Scaled

value

Unscaled

value

Scaled

value

Unscaled

value

Scaled

value

1 A 3090w 3381 3090 3237 3091 3219 3090 (CH)

2 A 3080s 3372 3082 3227 3081 3209 3080 (CH)

3 A 3070m 3367 3077 3223 3077 3205 3076 (CH)

4 A 3010w 3341 3053 3197 3053 3180 3011 (CH)

5 A 1580vs 1580w 1762 1610 1621 1548 1611 1594 (C C)

6 A 1500w 1756 1527 1620 1506 1611 1525 (C C)

7 A 1480s 1619 1479 1495 1480 1490 1475 (C C)

8 A 1460vs 1553 1419 1444 1458 1439 1453 (CC)

9 A 1410vs 1420 1405 1342 1435 1328 1420 (CC)

10 A 1400s 1297 1387 1295 1385 1289 1379 (CC)

11 A 1130vs 1130w 1227 1121 1190 1136 1188 1140 (CH) 12 A 1110s 1110w 1199 1095 1133 1121 1129 1117 (CH) 13 A 1080vs 1080w 1174 1073 1101 1089 1097 1086 (CH) 14 A 1070vs 1070w 1172 1071 1096 1085 1094 1083 (CH) 15 A 1000m 1000vs 1103 1008 1009 998 1011 1000 (CH) 16 A 960w 1080 987 985 940 982 972 (CH) 17 A 860vs 1020 887 904 863 903 866 (CH) 18 A 840w 998 868 882 842 883 847 (CH) 19 A 780vs 879 803 785 777 786 778 (CCl)

20 A 770vs 851 777 784 776 783 775 (CCl) 21 A 670vs 759 693 679 672 695 667 (CCC) 22 A 660w 660m 724 661 673 666 674 647 (CCC) 23 A 640w 607 649 544 582 548 586 (CCC) 24 A 560w 486 520 444 475 444 541 (CCC) 25 A 480w 464 459 430 460 430 460 (CCC) 26 A 400m 429 392 397 393 397 400 (CCC) 27 A 370w 398 363 369 365 369 372 (CCl) 28 A 210w 224 204 202 199 201 203 (CCl) 29 A 200w 212 193 197 195 197 198 (CCl) 30 A 180w 184 168 167 178 166 177 (CCl)

VS, very strong; S, strong; m, medium; w, weak; as, asymmetric; s, symmetric; , stretching; , in plane bending;, out plane bending; , twisting.

of1,3-DCB are distributed as Vib=21A +9A. In agreement with

CS symmetry all the 30 fundamental vibrations are active in both

Raman scattering and IR absorption. The harmonic-vibrational fre-

quencies calculated for 1,3-DCB at HF and B3LYP levels using the

triple split valence basis set along with the diffuse and polariza-

tion functions, 6-31++G (d, p) and 6-311++G (d, p) observed FT-IR

and FT-Raman frequencies for various modes ofvibrations have

been presented in Table 2. Comparison offrequencies calculated

at HF with the experimental values reveals the over estimation of

the calculatedvibrational modes due to the neglect ofanharmonic-

Fig. 4. Comparative graph ofIR intensities by HF andDFT (B3LYP).

ity in real system. Inclusion ofelectron correlation in the Density

functional theory to certain extends makes the frequency values

smaller in the comparison with the HF frequency data. Reduction

in the computed harmonic vibrations, although basis set sensitive

are only marginal as observed in the DFT values using 6-311++G (d,

p). Any way not withstanding the level ofcalculations, it is custom-

ary to scale down the calculated harmonic frequencies in order to

develop the agreement with the experiment.

Fig. 5. Comparative graph ofRaman activities by HF and DFT (B3LYP).

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Table 3

Comparative values ofIR intensities and Raman activities between HF/6-311++G (d, p), B3LYP/6-31++G (d, p) and B3LYP/6-311++G (d,p) of1,3-dichlorobenzene.

S.No. Calculated w ith H F/6-311++G ( d, p ) Calculated with B3LYP/6-31++G (d, p) Calculated with B3LYP/6-311++G (d, p)

IR intensity (Ai) Raman activity (I) IR intensity (Ai) Raman activity (I) IR intensity (Ai) Raman activity (I)

1 0.084 0.585 0.137 0.774 0.092 0.653

2 0.441 2.381 0.315 2.829 0.284 2.983

3 0.000 1.002 0.000 1.211 0.000 1.106

4 0.519 1.090 0.612 1.018 0.676 1.094

5 3.502 11.555 3.683 10.128 3.745 9.973

6 4.388 4.015 5.742 3.324 5.917 3.238

7 4.699 0.000 4.894 0.000 4.163 0.000

8 0.000 0.199 0.000 0.152 0.000 0.412

9 2.315 9.023 2.285 6.916 2.254 7.119

10 22.807 0.002 14.937 0.005 17.313 0.000

11 89.611 0.041 94.343 0.073 95.836 0.173

12 49.811 0.351 44.830 0.078 43.449 0.021

13 17.513 0.002 13.021 0.015 15.457 0.003

14 0.000 0.549 0.000 0.257 0.000 0.245

15 2.950 45.849 0.082 0.061 0.159 0.092

16 0.210 0.091 4.671 43.494 3.998 44.105

17 16.247 5.856 24.539 12.702 25.161 11.933

18 13.487 0.815 25.109 0.068 25.537 0.028

19 15.597 3.763 17.560 15.738 17.884 15.028

20 26.861 11.848 0.428 1.327 0.476 1.118

21 0.112 0.002 2.031 0.282 1.727 0.610

22 2.372 0.035 0.714 1.651 1.350 1.378

23 16.304 1.713 12.094 2.345 12.692 1.99024 70.187 0.352 71.970 0.001 75.789 0.008

25 28.724 9.205 26.590 9.012 85.876 21.950

26 90.110 21.504 85.849 21.836 28.054 9.002

27 5.576 65.768 5.426 88.391 4.741 83.047

28 1.089 50.034 0.916 60.323 0.499 56.381

29 3.044 152.901 1.774 171.154 1.313 166.631

30 0.474 57.359 0.522 68.733 0.764 65.751

4.2.1. Computed IR intensity and Raman activity analysis

Computed vibrational spectral IR intensities and Raman activi-

ties ofthe 1,3-DCB for corresponding wave numbers by HF method

of6-311++G (d, p) and DFT methods with B3LYP at 6-31++G(d, p)

and 6-311++G (d, p) basis sets have been collected in Table 3. 1,3-

DCB is a non polar and belongs to CS point group. Comparison ofIR

intensity and Raman activity calculated by HF and DFT with B3LYPat 6-31++G (d, p) and6-311++G(d, p) levels with experimental val-

ues exposes the variation ofIR intensities and Raman activities. In

the case of IR intensity, the values ofHF are found to be higher

than B3LYP at 6-311++G (d, p) levels whereas in the case ofRaman

Fig. 6. Bond length differences between theoretical (HFand DFT) approaches.

activity the effect is reversed. The similar effect was observed in the

previous report [23].

4.2.2. Computed vibrational frequency analysis

The comparative graph ofcalculated vibrational frequencies by

HF and DFT methods at HF/6-311++G (d, p), B3LYP/6-31++G (d, p)

and B3LYP/6-311++G (d, p) basis sets for the 1,3-DCB are given inFig. 9. From the figure, it is found that the calculated (unscaled)

frequencies by B3LYP with 6-311++G (d, p) basis sets are closer to

the experimental frequenciesthan HF method with 6-311++G(d, p)

basisset. This observation is supportedby the literature report [24].

The standard deviation (SD) calculation made between experimen-

Fig. 7. Bond angle differences between theoretical (HFand DFT) approaches.

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Table 4

Standard deviation offrequencies by HF 6-311++G(d, p),DFT (B3LYP) at 6-31++G (d, p) and 6-311++G(d, p) basis sets.

S.No. Basic set levels Total values Average Standard Deviation Deviation ratio

1 Experimental value 35,050 1168.33

2 HF/6-311++(d, p) 38,058 1268.6 77.05 2.40

3 B3LYP/6-31++(d, p) 35,672 1189.06 32.05

4 B3LYP/6-311++(d, p) 35,558 1185.26 29.13 2.64

Fig. 8. Dihedral angle differences between theoretical (HF and DFT) approaches.

tal and computedfrequencies (HF/DFT) for the 1,3-DCB is presented

in Table 4. According to the SD, the computed frequency deviation

decrease in going from HF/6-311++G (d, p) to B3LYP/6-31++G (d,

p) to B3LYP/6-311++G (d, p). The deviation ratio between HF/6-

311++G (d, p) and B3LYP/6-31++G (d, p) is 2.40 and HF/6-311++G(d, p) and B3LYP/6-311++G (d, p) is 2.64. It also proved that, the cal-

Fig.9. Comparative graphofcomputedfrequencies(HF andDFT) with experimental

frequencies.

culated frequencies by B3LYP/6-311++G (d, p) basis sets are closerto the experimental frequencies than HF method.

4.2.3. CH vibrations

The aromatic structure shows the presence ofCH stretching

vibrations in the region 31003000 cm1 which is the character-

istic region for ready identification of CH stretching vibrations

[2528]. The bands appeared at 3090, 3080, 3070 and3010 cm1 in

the 1,3-DCB have been assigned to CH ring stretching vibrations.

The CH in-plane ring bending vibrations are normally occurred as

a number of strong to weak intensity bands in the region 1300-

1000 cm1 [29]. In the present case, four CH in-plane bending

vibrations ofthe present compound are identified at 1130, 1110,

1080, 1070cm1. The calculated frequencies ofB3LYP/6-31++G (d,

p) and B3LYP/6-311++G (d, p) methods for CH in-plane bendingvibrations showed excellent agreement with recorded spectrum as

well as literature data. The CH out-of-plane bending vibrations

are normally observed in the region 1000809cm1 [3035]. The

four CH out-of-plane bending vibrations are observed at 1000,

960,860 and840 cm1. Thesein-planeand out-of-plane vibrational

frequencies are found to be well within their characteristic region.

4.2.4. CCvibrations

Generally C C stretching vibrations in aromatic compounds

form a band in the region of 14301650 cm1 [36,37]. Accord-

ingly, in the present study, the C C stretching vibrations of1,3-DCB

are observed at 1580, 1500 and 1480 cm1. The theoretically

computed frequencies for CH in-plane bending vibrations by

B3LYP/6-311++G (d, p) method showed excellent agreement withrecorded spectrum as well as literature data. Ring CC stretching

vibrations normally occur in the region 15901430 cm1[37]. In

the present case, the CC stretching vibrations are found at 1460,

1410 and 1400 cm1. When compared to the literature range cited

above, there is a considerable decrease in frequencies which is also

worsening with the increase ofmass ofsubstitutions. In the present

work, three strong bands found at 670, 660 and 640 cm1 are

assigned to CCC in-plane bending and three supplementary bands

Fig. 10. Variation ofthe atomic charges for different basis sets ofHF and DFT.

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Table 5

Theoretically computed zero point vibrational energy (kcal mol1), rotational constants (GHz), rotational temperature (K), thermal energy (kcalmol1), molar capacity at

constant volume (calmol1 K1) entropies (calmol1 K1) and dipole moment (Debye) for 1,3-dichlorobenzene.

Parameters HF/6-311++ (d, p) B3LYP/6-31++ (d, p) B3LYP/6-311++(d, p)

Zero point vibration energy 54.429 51.018 50.854

Rotational constants

2.856 2.804 2.815

0.864 0.849 0.852

0.663 0.652 0.654

Rotational temperature

0.137 0.134 0.135

0.041 0.040 0.0400.031 0.031 0.031

Energy

Translational 0.889 0.889 0.889

Rotational 0.889 0.889 0.889

Vibrational 56.578 53.436 53.270

Total 58.355 55.213 55.047

Molar capacity at constant volume

Translational 2.981 2.981 2.981

Rotational 2.981 2.981 2.981

Vibrational 17.157 18.948 18.937

Total 23.119 24.909 24.899

Entropy

Translational 40.845 40.845 40.845

Rotational 28.285 28.338 28.328

Vibrational 11.330 12.901 12.909

Total 80.461 82.085 82.083

Dipole moment 1.938 2.250 2.223

Table 6

Mulliken atomic charges of1,3-dichlorobenzene performed at HF/6-311++G (d, p), B3LYP/6-31++G (d, p) and B3LYP/6-311++G (d, p) basis sets.

Atoms Mulliken atomic charges

HF/6-311++G (d, p) B3LYP/6-31++G (d, p) B3LYP/6-311++G (d, p)

C1 0.346 0.251 0.455

C2 0.379 0.645 0.762

C3 0.346 0.251 0.455

C4 0.579 0.375 0.533

C5 0.577 0.003 0.464

C6 0.579 0.375 0.533

H7 0.234 0.123 0.174

H8 0.215 0.138 0.180

H9 0.224 0.136 0.192

H10 0.215 0.138 0.180Cl11 0.266 0.179 0.326

Cl12 0.266 0.179 0.326

are assigning at 560, 480 and 400 cm1 to CCC out-of-plane bend-

ing. These assignments are in line with the assignments proposed

by the literature [38,39].

4.2.5. CCl vibrations

The vibration belonging to the link between the CCl is signifi-

cant to discuss here since mixing ofvibrations are possible due to

the lowering ofthe molecular symmetry and the presence ofheavy

atoms on the periphery ofthe molecule [40]. The assignments of

CCl stretching and deformational modes have been made through

comparison with similar assignments in other halogens substitutedbenzene derivatives. The CCl stretching vibration gives generally

a strong band in the region 750580 cm1 [41,42]. In this case,

a strong band for CCl stretching vibration is observed at 780,

770 cm1. CCl in plane bending vibration compounds form a band

in the region of385265 cm1 [43]. Accordingly, the bands are

identified at 370, 210 cm1 have been assigned to CCl in-plane

bending modes. The CCl out-of-plane bending vibrations have

been established at 200, 180cm1.

4.2.6. Other molecular properties

Several calculated thermodynamic parameters are presented in

Table 5. Scale factors have been recommended [44] for an accu-

rate prediction in determining the zero-point vibration energies

(ZPVE), and the entropy, Svib (T). The variations in the ZPVEs seem

to be insignificant. The total energies are found to decrease with

the increase ofthe basis set dimension. The changes in the total

entropy of1,3-DCB at room temperature at different basis set are

only marginal.

4.2.7. Mulliken atomic charges

The total atomic charges of 1,3-dichlorobenzene obtained by

Mulliken population analysis with different (HF) with 6-311++G(d,

p) and DFT (B3LYP) with 6-31++G (d, p) and 6-311++G (d, p) basis

sets were listed in Table 6. The negative values on C2, C4, C5and C6

atom in the aromatic ring lead to a redistribution ofelectron den-sity. Due to this strong negative charges, C1 and C3 accommodate

higher positive chargeand becomes more acidic. The atomic charge

obtained from B3LYP/6-311++G (d, p) basis set shows that Chlorine

atom is more acidic due to more positive charge. The better repre-

sented graphical form ofthe results has been done in Fig. 10. Fig. 10

shows Mulliken charge ofatoms for (HF) with 6-311++G (d, p) and

DFT (B3LYP) with 6-31++G (d, p) and 6-311++G (d, p) basis sets,

respectively.

5. Conclusion

Attempts have been made in the current paper for the proper

frequency assignments for the compound 1,3-dichlorobenzene

from the FT-IR and FT-Raman spectra. The equilibrium geometries,

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vibrational frequencies, infrared intensities and Raman activities

are calculated and analyzed by HF and DFT(B3LYP) levels oftheory

utilizing 6-31++G (d, p) and 6-311++G (d, p) basis sets. Comparison

between the calculated vibrational frequenciesand the experimen-

tal values indicates that both the methods can predict the FT-IR

and FT-Raman spectra ofthe title compound well. The Scaling fac-

tors used in this study made a reliable agreement between the

calculated and experimental values. In particular, the results of

DFT-B3LYP method indicate better fit to experimental ones than

ab initio HF upon evaluation ofvibrational frequencies. The opti-

mized geometrical parameters calculated at B3LYP basis sets are

slightly larger than those calculated at HF level. The atomic charges

and dipole moment in the title molecule are also discussed elabo-

rately. Several thermodynamic parameters ofthe title molecule are

comparatively discussed.

References

[1] Q.Zhu, X.M.Zhang, A.J.Fry,PolymerDegradation andStability 57 (1997) 4347.[2] N. Sundaraganesan, B. Anand, C. Meganathan,B.D. Joshua,Spectrochimica Acta

A 68 (2007) 561566.[3] B. Halliwell, J.M.C. Gutteridge, Free Radicals in Biology and Medicine, 2nd ed.,

Oxford University Press, Oxford, 1989.[4] F. Gugumus, Oxidation Inhibition in Organic Materials, vol. 1, CRC Press, Boca

Raton, 1990.[5] M. Weber, M. Weber, M. Kleine-Boymann, Phenol in Ullmanns EncyclopediaofIndustrial Chemistry, Wiley-VCH, Weinheim, 2005.

[6] M. Rossberg, et al., Chlorinated Hydrocarbons in Ullmanns Encyclopedia ofIndustrial Chemistry, Wiley-VCH, Weinheim, 2006.

[7] Gerald Booth Nitro Compounds, Aromatic in UllmannsEncyclopedia ofIndus-trial Chemistry, John Wiley & Sons, New York, 2007.

[8] R. Krishnan, J.S. Binkley, R. Seeger, Journal of Chemical Physics 72 (1980)650656.

[9] A.D. Becke, Physics Review A 38 (1988) 30983102.[10] C.Lee,W. Yang, R.G. Parr, PhysicsReview B 37 (1988) 785790.[11] A.D. Becke, Journal ofChemical Physics 98 (1993) 5648.[12] J. Zhang, H.M. Xiao, Journal ofChemical Physics 116 (2002) 10674.[13] X.J. Xu, H.M. Xiao, X.H. Ju,X.D.Gong,W.H.Zhu, Journal ofPhysical Chemistry A

110 (2006) 5929.[14] Z.X. Chen, J.M. Xiao, H.M. Xiao, Y.N. Chiu, Journal ofPhysical Chemistry A 103

(1999) 8062.[15] D.C. Young, Computational Chemistry: A Practical guide for applying Tech-

niques to Real World Problems (Electronic), John Wiley& Sons Inc., New York,

2001.

[16] M. Sekerci,Y. Atalay,F. Yakuphanoglu, D. Avci,A. Basoglu,Spectrochimica Acta,A 67 (2007) 503508.

[17] A.P. Scott, L. Radom, Journal ofPhysical Chemistry 100 (1996) 16502.[18] Gaussian 03 Program, Gaussian Inc., Wallingford, CT, 2000.[19] M.J. Frisch, A.B. Nielsen, A.J. Holder, Gauss View Users Manual, Gaussian Inc.,

Pittsburgh, PA, 2000.[20] M. Bakiler, I.V. Maslov, S. Akyuz, Journal of Molecular Structure 475 (1999)

8388.[21] A.K. Hermetet, L.J. Ackerman, K.K. Eilts, T.K. Johnson, J.K. Swearinggen, J.M.

Geisen, K.I. Goldberg, W. Kaminsky, D.X. West, Journal ofMolecular Structure605 (2002) 241245.

[22] K.M. Gough, B.R. Henry, Journal ofPhysical Chemistry 87 (1983) 3804.[23] S. Ramalingam, S. Periandy, M. Govindarajan, S. Mohan, Spectrochimica ActaA

75 (2010) 13081314.[24] S. Ramalingam, S. Periandy, B. Narayanan,S. Mohan, SpectrochimicaActa A 76

(2010) 8492.[25] G. Socrates,Infraredand Raman Characteristic Group FrequenciesTables and

Charts, 3rded., Wiley,New York, 2001.[26] V. Krishnakumar, V. Balachandran, T. Chithambarathann, Spectrochimica Acta

A 62 (2005) 918925.[27] W.O. George, P.S. Mcintyre, Infrared Spectroscopy,John Wiley& Sons, London,

1987.[28] J. Coates, R.A. Meyers, Interpretation ofInfrared Spectra: A Practical Approach,

John Wiley and Sons Ltd, Chichester, 2000.[29] N. Sundaraganesan,H. Saleem,S. Mohan, M.Ramalingam,V. Sethuraman,Spec-

trochimica Acta A 62 (2005) 740751.[30] V.K. Kumar, R.J. Xavier, Indian Journal of Pure and Applied Physics 41 (2003)

597602.[31] V.K. Kumar, N. Prabavathi, SpectrochimicaActa A 71 (2008) 449457.[32] A. Altun,K. Golcuk, M. Kumru, Journal ofMolecularStructure (Theochem) 637

(2003) 155160.[33] S.J. Singh, S.M. Pandey, Indian Journal of Pure and Applied Physics 12 (1974)

300304.[34] Y.-X.Sun, Q.-L.Hao,Z.-X.Yu,W.-J.Jiang,L.-D.Lu, X.Wang,SpectrochimicaActa

A 73 (2009) 892901.[35] N. Sundaraganesan, B.D. Joshua, T. Rajakumar, Indian Journal of Pure and

Applied Physics 47 (2009) 248258.[36] W.J. Taylor, K.S. Pitzer, Journal ofResearchofthe National Bureau ofStandards

38 (1947) 1.[37] G. Varsanyi, Assignments for vibrational spectra of seven hundred benzene

derivatives,vol. 1, Wiley,New York, 1974.[38] S. Periandy, S. Mohan, Proceedings National Academic Science India 68(A), III

(1998).[39] A.-S. Hussein, K. Howard, Journal ofMolecular structure (GB) 42 (1977) 37.[40] C. Lee, W. Yang,R.G. Parr, Physics Review B 37 (1988) 785789.[41] C.S. Hiremath, T. Sundius, Spectrochimica Acta A 74 (2009) 12601266.[42] E.E. Mooney, SpectrochimicaActa 19 (1968) 877881.[43] S. George, Infrared and Raman Characteristic Group Frequencies, Tables and

Charts, 3rd ed., Wiley, Chichester, 2001.[44] M.A. Palafox, InternationalJournal ofQuantum Chemistry 77 (2000) 661.

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