CHAPTER 4

AB INITIO HF AND DFT SIMULATIONS, FTIR AND FT-RAMAN

VIBRATIONAL ANALYSIS OF -CHLOROTOLUENE

4.1. INTRODUCTION

-chlorotoluene or Benzyl chloride, is an organic compound consisting of a

phenyl group substituted with a chloromethyl group. It has the molecular formula

C7H7Cl. This is a organochlorine compound used as chemical building block.

This is used in organic synthesis for the introduction of the benzyl protecting group

for alcohols and carboxylic acids. Benzyl chloride also reacts readily with metallic

magnesium to produce a Grignard Reagent. Because of its utility in the synthesis of

amphetamine-class drugs, it is mentioned as List II drug precursor chemical. -

chlorotoluene is a lachrymator and used as a war gas.

4.2. LITERATURE SURVEY

The vibrational spectra of toluene and its derivatives have been extensively

studied and analyzed in the past years by several workers [1-8] but only little effort

has been spent on chlorotoluenes. The microwave spectrum of p-chlorotoluene was

studied by Herberich et al [3] and the NMR spectrum of o-chlorotoluene in a liquid

crystal was analyzed by Diehl et al [6]. The analysis on the basis of quality,

methodology, experimental and theoretical aspects on toluene and its derivatives were

explained by many other workers [9-22].

Syam Sundar [9] studied the vibrational spectra of substituted toluenes (4-

amino-3-bromotoluene and 5-amino-2-bromotoluene) using infrared absorption and

laser Raman spectra by assuming Cs point group symmetry. The vibrational spectra

could be analysed in terms of the fundamental characteristic of the molecules,

overtones and combinations on the basis of Varsanyis classification of the benzene

derivatives.

The computed force constants and vibrational spectra of toluene were

extensively studied by Xie et al [10]. The complete harmonic force field and dipole

moment derivatives have been computed for toluene at the Hartree-Fock level using a

4-21G basis set. The six scale factors optimized for benzene were used to scale the

computed harmonic force constants of toluene. The vibrational frequencies of toluene

computed from this scaled quantum mechanical force field were quite good. After a

correction was made to two previously proposed spectral assignments, the mean

deviation from the experimental frequencies is only 7.8 cm1

except for the

frequencies related to the methyl group. Five more scale factors for the vibrational

modes of the methyl group were reoptimized. The final comparison showed an overall

mean deviation of 7.5 cm1

between the theoretical spectrum and the experimental

spectrum..

The microwave rotational spectra of orthochlorotoluene, C6H4CH3Cl, have

been measured in the frequency region 840 GHz by Nair et al [11]. Spectra due to

both isotopic species 35

Cl and 37

Cl have been observed. The hyperfine structure due

to the chlorine nuclear quadrupole interaction in both isotopic species has been

studied. Analysis of the spectra yields rotational and nuclear quadrupole coupling

constants for both isotopic species. No splitting which could be attributed to the

internal rotation of the methyl group was observed.

The microwave spectrum of an excited vibrational state of orthochlorotoluene

has been identified and analyzed extensively by Rajappan Nair [12]. The rotational

constants and nuclear electric quadrapole hyperfine interaction constants for 35

Cl and

37Cl species were reported. Accordingly, no sign of splitting due to the internal

rotation has been observed and the barrier hindering internal rotation is believed to be

high in this molecule. Furthermore, the study concluded that microwave study is

necessary to obtain an accurate experimental value of the potential barrier in

orthocholorotoluene. The vibrational frequency has been calculated as 163 cm-1

from

the relative intensities of the ground and excited state microwave spectra. The

vibrational state is expected to be the first torsional state of the molecule.

A theoretical study on the molecular structures of toluene, para-fluorotoluene,

para-chlorotoluene, and 4-methylpyridine and their sixfold internal rotational barriers

was conducted by Chen et al [13]. In their study, two kinds of sixfold internal

rotational configurations of toluene, para-fluorotoluene, para-chlorotoluene, and 4-

methylpyridine were calculated using HartreeFock (HF), second-order Mller

Plesset (MP2), and Beck's three parameter hybrid functional using the LYP

correlation functional (B3LYP) theory methods with various high-level basis sets.

Structures and energies were compared for different configurations. Calculations

indicated that the orthogonal configuration has a local minimum while the planar

configuration is a transition structure. Furthermore, geometries of the orthogonal and

the planar configurations were quite similar, except for a methyl CH bond. Sixfold

internal rotational barriers were calculated from the energy difference of two different

configurations. From the results, the study concluded that the HF methods

underestimated the rotational barriers, but MP2 calculations overestimated them.

However, the density functional theory (DFT) method was a reliable method since the

calculated internal rotational barriers were similar to the experimental ones.

An investigation of CH stretching vibrations in benzene and toluene in their S1

states has been carried out using UVIR and stimulated RamanUV double resonance

spectroscopic methods by Minejima et al [14]. They observed two CH stretching

vibrations in benzene whereas as both aromatic CH and methyl CH stretching

vibrations were observed in toluene. Both benzene and toluene exhibited strong

anharmonic resonance lead to the appearance of a large number of bands in the

30003100 cm1

regions. The observed frequencies of CH stretching vibrations in the

S1 state in both benzene and toluene were higher than the corresponding values in the

S0 state. On the other hand, methyl CH stretching vibrations in the S1 state of toluene

occur at a lower frequency than those in the S0 state.

An analysis of vibrational spectra of chlorotoluene based on density functional

theory calculations were carried out by Zhou et al [15]. In that study, the

conformational behavior and structural stability of chlorotoluene were investigated

using RHF/631G(d) basis set and DFT (BLYP,LSDA,BP86,B3LYP,B3P86) levels.

By comparing the experimental values with the theoretical ones, of the five DFT

methods, BLYP reproduces the observed fundamental frequencies most satisfactory

with the mean absolute deviation of the non-CH stretching modes less than 10 cm-1

.

Moreover, the study also implies that two hybrid DFT methods were found to yield

frequencies, which were generally higher than the observed fundamental frequencies.

Furthermore, the study also depicted that it was a promising approach for

understanding the observed spectral features.

Gerhard et al [16] studied the internal rotation and chlorine nuclear quadrupole

coupling of o-chlorotoluene studied by microwave spectroscopy and ab initio

calculations. The microwave spectrum of the molecule was taken using molecular

beam Fourier Transform Microwave spectrometers (MB-FTMW) in the frequency

range of 4-23GHz. The objective of this study was to improve the rotational

constants, determine certifugal distortion constants and the complete quadupole

coupling tensor for both chlorine isotopomers. Due to the adoption of high resolution

molecular beam technique, this analysis was yielded improved rotational constants,

centrifugal distortion constants and the complete chlorine nuclear quadrupole

coupling tensor for the first time. From the torsional fine structure, the barrier to

internal rotation of the methyl group was found to be 5.5798 (52) kJ mol-1

. The

molecular constants obtained from the spectral analysis were interpreted in terms of

structural, dynamical and electrical properties of the molecule.

Scaled quantum mechanical reinvestigation of the vibrational spectrum of

toluene has been reported by Baker [17]. In this study, the IR spectrum of liquid

toluene between 400 and 4000 cm1

by Keefe and coworkers [J.E. Bertie, Y. Apelblat,

C.D. Keefe, J. Mol. Struct. 750 (2005) 78] has been reexamined theoretically using

the scaled quantum mechanical (SQM) force field method. Accordingly, it was

proposed that three bands which were assigned as fundamentals : a weak, broad

shoulder at 947 cm1

(combination band), an unassigned feature at 1467 cm1

and a

medium broad band at 2979 cm1

, also assigned as a combination band. An average

deviation of just 5.28 cm-1

has been found out between the observed and theoretically

predicted vibrational fundamentals. Moreover, analysis involving free rotation of the

methyl group and interpretation of the vibrational spectrum in terms of C2v symmetry

for the phenyl ring and C3v for the methyl group very likely contributed to the

experimental misassignments.

The experimental and theoretical study on molecular structure and vibrational

spectra of 4-nitrotoluene were interpreted by Ramalingam et al [18]. The FTIR and

FTRaman spectra of the molecule were taken in the range of 4000-100 cm-1

. The

experimental determinations of vibrational frequencies were compared with those

obtained theoretically from ab initio HF and DFT quantum mechanical calculations

using HF/6-31G (d, p), B3LYP/6-31++G* (d, p) and B3LYP/6-311++G* (d, p) basis

sets. The geometries and normal modes of vibrations (scaled) obtained from ab initio

HF and B3LYP calculations are in good agreement with the experimentally observed

data. Also, the report concludes that the vibrations of NO2 and CH3 groups were

coupled with skeletal vibrations.

A combined experimental and theoretical study of 2-chlorotoluene ad 2-

bromotoluene was done by Govindarajan et al [19] using FTIR and FT-Raman

spectra. The molecular structure, fundamental vibrational frequencies and

intensity of the vibrational bands were interpreted with the aid of structure

optimizations and normal coordinate force field calculations based on HF and

DFT methods with different basis set combinations. The complete vibrational

assignments were made on the basis of potential energy distribution (PED). In

addition, the effects due to the substitutions of methyl group and halogen bond

were investigated. The results of the calculations were applied to simulated

spectra of the title compounds, which show excellent agreement with observed

spectra.

Molecular structure and vibrational spectra of o-chlorotoluene, m-

chlorotoluene, and p-chlorotoluene by ab initio HF and DFT calculations were

examined by Ren et al [20]. The vibrational frequencies of these compounds were

obtained theoretically by ab initio HF and DFT/B3LYP calculations employing the

standard 6-311++G(d,p) basis set for optimized geometries and were compared with

Fourier transform infrared (FTIR) in the region of 400-4000 cm-1

and with Raman

spectra in the region of 100-4000 cm-1

. Complete vibrational assignment, analysis and

correlation of the fundamental modes for these compounds have been presented in the

work. In order to cope up with the experimental values, the theoretically calculated

harmonic vibrational frequencies were scaled down with the appropriate scaling

factors.

Spectral studies and quantum chemical calculations of 4-chlrotoluene was

done by Anbarasan et al [21]. In this work, the combined experimental and

theoretical study on molecular and vibrational structure of 4-chlorotoluene (4CT) was

studied based on Hartree-Fock (HF) and density functional theory (DFT) using the

hybrid functional B3LYP. The Fourier Transform Infrared (FTIR) and Fourier

Transform Raman (FT-Raman) spectra of 4CT were recorded in the solid phase. The

optimized geometry was calculated by HF and B3LYP methods with 6-31G(d,p) and

6-311++G(d,p) basis sets. The harmonic vibrational frequencies, infrared intensities

and Raman scattering activities of the title compound were performed at same level of

theories. The thermodynamic functions of the title compound was also performed at

HF/6-31G(d,p) and B3LYP/6-311++G(d,p) level of theories. A detailed interpretation

of the infrared and Raman spectra of 4CT was reported. The observed and the

calculated frequencies are found to be in good agreement. The experimental spectra

also coincide satisfactorily with those of theoretically constructed spectrograms.

With the aid of above seen literatures, it is clear that there is no quantum

mechanical analysis on this -chlorotoluene molecule Hence, a detailed vibrational

analysis has been carried out here for knowing the vibrational wavenumbers,

geometrical parameters, modes of vibrations, dipole moment, rotational constants,

atomic charges and other thermodynamic parameters of this molecule.

These parameters were investigated using HF and B3LYP calculations with

6-311G(d), 6-311++G(d) basis sets. Specific scale factors were also used and

employed in the predicted frequencies.

4.3. COMPUTATIONAL DETAILS

The molecular structure optimization of the title compound and corresponding

vibrational harmonic frequencies were calculated using HF and the DFT with Beckee-

3-Lee-Yag-Parr (B3LYP) combined with 6-311G(d), 6-311++G(d) basis sets using

GAUSSIAN 03 program package without any constraint on the geometry. Geometries

have been first optimized with full relaxation on the potential energy surfaces at

HF/6-311G(d), 6-311++G(d) basis sets. The geometry was then re-optimized at

B3LYP level using 6-311G(d), 6-311++G(d) basis sets. The optimized geometrical

parameters, true rotational constants, fundamental vibrational frequencies, IR

intensity and Raman Activity were calculated using the Gaussian 03 package. The

atomic charges, dipole moment and other thermodynamical parameters were also

calculated theoretically using the Gaussian 03 package.

By combining the results of the GAUSSVIEW program with symmetry

considerations, along with the available related molecules, vibrational frequency

assignments were made with a high degree of accuracy. However, the defined

coordinate form complete set and matches quite well with the motions observed using

GAUSSVIEW program. The FTIR and FT Raman spectrum were taken in the range

of 3600 10 cm-1

in the solid phase in order to analyse the very low frequency

vibrations.

In order to improve the calculated values in agreement with the experimental

values, it is necessary to scale down the calculated harmonic frequencies. The

vibrational frequencies calculated at B3LYP/6-311G(d), 6-311++G(d) level are scaled

by 0.98 for wavenumbers less than 1700 cm-1

and 0.97 for higher wavenumbers. The

scaled values used in HF/6-311G(d), 6-311G(d) are 0.905 for wavenumbers less than

1700 cm-1

and 0.92 for higher wavenumbers.

4.4. RESULTS AND DISCUSSION

4.4.1. Molecular Geometry

The molecular structure along with numbering of atoms of -chlorotoluene is

shown in Fig 4.1. The most optimized structural parameters (bond length, bond angle

and dihedral angle) were calculated by HF, DFT/B3LYP with 6-311G(d) and

6-311++G(d) basis sets as shown in Table 4.1.

From the experimental values of literature [22], C-C single bond length is

1.5037 , H-C single bond length is 1.0853 and C-Cl bond length is 1.827 for

chlorotoluene. The C-Cl bond length (Cl atom of CH2Cl group) is 1.821 in the

earlier work done by Durig et al [23] which is more consistent with the results

obtained from the electron diffraction study [24]. From the literature [25] C-C bond

length increased from 1.386 to 1.414 , while the C-H bond length varies from 1.076

to 1.073 . From the literature [15], C-C single bond length is 1.4009 , H-C single

bond length is 1.0875 and C-Cl bond length is 1.8405 for chlorotoluene.

As there are no earlier literature values in this molecule, the theoretically

calculated optimized parameters with different basis sets are tabulated in Table 4.1.

From the table 4.1, it is very interesting to note that the C-C bond lengths are equal

with its neighbouring pairs (C5-C6, C2-C3/ C4-C5, C3-C4/ C1-C2, C1-C6 ) within the

benzene ring. The bond length of C5-C6, C2-C3 is 1.3839 , 1.3848 , 1.3916 ,

1.3912 , the bond length of C4-C5, C3-C4 is 1.3849 , 1.3875 ,1.3938 ,1.3944

and the bond length of C1-C2, C1-C6 is 1.3879 , 1.3886 , 1.3984 ,1.3989 for

HF and B3LYP with 6-311 G(d) and 6-311++G(d) respectively. The length of CC

bond connecting the methyl group and the benzene ring calculated at B3LYP level are

1.4955, 1.4961 while for C-Cl bond length in CH2Cl, it is 1.8431, 1.841

respectively. The calculated bondlength for C-Cl differs from the earlier literature

values because in this molecule the Cl atom is attached with CH2 group while in the

earlier literatures, it is directly connected with benzene ring. The HF/6-311 G(d) and

6-311++ G(d) bond lengths are slightly shorter due to the neglect of electron

correlation, while the B3LYP/6-311 G(d) and 6-311++ G(d) bond lengths are closer

to the experimental data due to slightly exaggerated electron correlation effect. The

bondlength variation in the molecule with different methods is compared in the Fig.

4.2 which shows that the C-Cl bond length is higher than other bond lengths in the

molecule.

4.4.2. Vibrational assignments

-chlorotoluene molecule is considered under Cs point group symmetry,

having 15 atoms with 39 normal modes of vibrations which are active in both Raman

scattering and Infrared absorption. Out of 39 vibrations, 26 of these modes should be

planar (A) and 13 should be non planar (A). ie., Vib = 26 A + 13 A.

The detailed vibrational analysis of fundamental modes with FTIR and FT

Raman experimental frequencies, unscaled and scaled vibrational frequencies using

HF method with 6-311G(d), 6-311++G(d) basis sets, IR intensity, Raman activity,

depolarization ratio, reduced mass and force constant of -chlorotoluene were

reported in the Table 4.2 and Table 4.3 respectively. In Table 4.4 and Table 4.5, the

values are further calculated using B3LYP method with same basis sets. The

experimental Infrared and Raman spectra in solid phase, the calculated FT IR and FT

Raman spectra by HF and B3LYP methods and comparison of corrected frequencies

to normalized IR intensities in both methods are shown in Figures 4.3 to 4.7

respectively.

4.4.2.1. C-H Vibrations

In the aromatic compounds, the C-H stretching vibrations normally occur at

3100 3000 cm-1

[26]. These vibrations are not found to be affected due to the nature

and position of the substituent. Most of the aromatic compounds have nearly four

infra red peaks in the region 3080 - 3010 cm-1

due to ring C-H stretching

bonds [27-28]. Accordingly, here the FTIR band at 3100 cm -1

(w) is assigned to

symmetrical stretching vibration whereas the other bands at 3095 (FTIR) , 3080 cm-1

(FTIR), 3070 cm -1

(FT-R) and 3040 cm -1

(FTIR) are assigned to asymmetrical

stretching asymmetric stretching vibrations. Here, one CH symmetrical vibrational

frequency is greater than the asymmetrical vibrational frequency.

The C-H in plane bending vibrations usually occurs in the region

1300-1000 cm-1

and are very useful for characterization purposes [29]. It is noted

from literature [30] that strong band around 1200 cm-1

appears due to valence

oscillations in toluenes and substituted toluenes which very much coincides with the

assignment in this work where there is a strong peak appeared at the similar frequency

in FTIR. According to the infrared peaks appeared in the fig 4.2. the bands at

1200 cm -1

(strong), 1180 cm -1

(w), 1070 cm -1

(s) and 1020 cm-1

while the peak at

1030 cm -1

(s) in FT-Raman (Fig.4.3) are assigned to C-H in-plane bending vibrations.

All the peaks occurred due to CH in-plane bending vibrations are in the expected

range as reported in the earlier literatures.

The strong peaks below 900 cm-1

ie., around 727 and 693 cm-1

clearly

indicate its aromatic nature. Substitution patterns on the ring can be judged from the

out-of-plane bending of the ring C-H bonds in the region 1000-700 cm-1

and these

bands are highly informative [31]. The strong peak at 700 cm-1

is due to four adjacent

hydrogen atoms in the benzene ring confirm the mono substituted nature of the title

compound. Also, the mono substituted benzene show only a strong band around

700 - 800 cm-1

[32]. In line with the above said literatures, in this work, there is a

strong peak at 700 cm-1

in FT-Raman confirms the mono substituted and aromatic

nature of the molecule. Moreover, here, the peaks at 1000 cm-1

(s), 990 cm-1

(w), 960

cm-1

(w), 810 cm-1

(s), 700 cm-1

(s) and 610 cm-1

(w) are noted as the C-H out-of-

plane bending vibrations which agree well with the earlier literature values [31,32].

4.4.2.2. CH2 and C-CH2 Vibrations

For the assignments of CH2 group frequencies, basically six fundamentals can

be associated to each CH2 group namely symmetric and asymmetric stretch;

scissoring and rocking which belongs to in-plane vibrations and two out-of-plane

vibrations viz., wagging and twisting modes, which are expected to be depolarized

[33]. The asymmetric CH2 stretching vibrations are generally observed above 3000

cm-1

, while the symmetric stretch will appear between 3000 and 2900 cm-1

[34-36]. In

this molecule, the asymmetric and symmetric stretching vibrations are observed in

3010 cm -1

and 2980 cm-1

respectively.

For n-alkyl benzenes, the assignment of the fourth skeletal C-C stretching

mode at about 1464cm-1

is quite problematic, since this band is frequently masked by

the more intense bands at 1446-1465 cm-1

arising from the CH2 scissoring vibrations

[37-38]. For cyclohexane, the CH2 scissoring mode has been assigned to the medium

intensity IR bands at about 1450 cm-1

[39-40]. Methelene wagging and twisting

vibrations usually occur between the range 1350-1150 cm-1

[41]. In this work, the

strong band at 1500 cm-1

in FTIR is assigned to the CH2 scissoring vibration which

greater than the expected range approximately by 35 cm-1

shows that it is affected by

the skeletal vibration of the ring.

The band at 910 cm-1

was assigned to CH2 rocking in-plane-bending vibration,

while CH2 wagging and twisting (out of plane bending) vibrations at 1270 and 1160

cm-1

respectively which exactly coincides with the reported value of the earlier work

[41].

Even though the waging and twisting values are in the expected range, the

frequency occurred for wagging vibration is comparatively less indicates that the

presence of chlorine atom shifts its wagging vibration to lower frequency region.

Besides, the strong bands at 800 cm-1

(FTIR) , 770 cm-1

(both) and 270 cm-1

(FTIR) assigned to C-CH2 stretching, in-plane-bending vibrations and out-of-plane

bending vibrations respectively.

4.4.2.3. Skeletal vibrations

Generally the C=C stretching vibrations in aromatic compounds form the band

in the region of 1430-1650 cm-1

[31,42]. According to Socrates [43], the presence

of conjugate substituent such as C=C causes a heavy doublet formation around the

region 1625-1575 cm-1

and the C-C stretching vibrations occurs between the range

1300-1500 cm-1

. The six ring carbon atoms undergo coupled vibrations, called

skeletal vibrations and give a maximum of four bands in the region 1660 1420 cm-1

[44].As predicted in the earlier references, in this compound, the prominent peaks at

1610, 1600 and 1590 cm-1

are due to strong C=C stretching vibrations and there is a

short of one peak in C=C stretching vibration as said from the earlier referernce and

the missing C=C vibrations is dominated by the in-plane CH2 vibration. The FTIR

peaks at 1390 cm-1

, 1320 cm-1

and a strong Raman peak at 1270 cm-1

are assigned to

C-C stretching modes. These C-C stretching vibrations are coupled vibrations with

CH in-plane modes.

The CCC vibrations are assigned in corresponding tables which are coincides

with the earlier values predicted in literature [30].

4.4.2.4. C-Cl and C-CH2Cl vibrations

The presence of halogen on alkyl substituted aromatic ring can be detected

indirectly from its electronic impact on the in-plane C-H bending vibrations [45]. The

substitution pattern in an aromatic is identified by looking at the C-H out of plane

bending bands and also from the combination bands between the ranges

1650-2000 cm-1

. The position of absorption of the out-of-plane bending bands

depends on the number of adjacent hydrogen atoms on the ring. Mono-substituted

benzene displays two very strong bands between 690-710 cm-1

and 730-770 cm-1

[35].

The strong peak in FT Raman at 1000 cm-1

confirms the presence of chlorine atom in

this molecule. The C-Cl stretching vibrations give generally strong bands in the

region 730 580 cm-1

. In accordance with the said literature values, here, the peak at

690 cm-1

in FTIR is assigned to C-Cl stretching vibration which also imply that the

compound is a mono-chlorinated compound in the alkyl substituted aromatic ring.

The peak at 480 cm-1

and 120 cm-1

in fig.4.2 are assigned to C-Cl in-plane and out-of-

plane bending vibrations which are close agreement with the earlier literature [46].

Besides, the stretching and in-plane bending vibrations of C-CH2Cl are

assigned to strong intensity band of 1210 cm -1

, 560 cm-1

while the calculated

wavenumber by theoretical methods (mode 39) with different basis sets is assigned to

C-CH2Cl out-of plane bending vibration as in Tables 4.2 to 4.5.

4.4.3. Mulliken Population analysis

The total atomic charges of -chlorotoluene obtained by Mulliken population

analysis with different HF and B3LYP basis sets were listed in Table 4.6. The charge

on individual atoms is reported in the figure 4.8. From the result it is clear that the

substitution of CH2Cl atoms in the aromatic ring leads to a redistribution of electron

density. The - electron withdrawing character of the chlorine atom in this title

compound is demonstrated by the decrease of electron density on C12 atom. The

atomic charges in the CH2 group are almost identical. The atomic charge obtained

from 6-311++G(d) basis set shows that C1 atom is more acidic due to more positive

charge.

4.4.4. Other molecular properties

Several calculated thermodynamical parameters, rotational constants,

rotational temperatures and dipole moment are presented in Table 4.7. The Zero-Point

Vibration Energies (ZPVE), the entropy, Svib(T) and the molar capacity at constant

volume were calculated. The variations in the ZPVEs seem to be insignificant. The

total energies are found to decrease with the increase of the basis set dimension. The

changes in the total entropy of -chlorotoluene at room temperature at different basis

sets are only marginal. The dipole moment of the molecule was also calculated with

HF/B3LYP 6-311G(d) and 6-311++G(d) basis sets.

4.5. CONCLUSION

Attempts have been made in the present work for the proper frequency

assignments for the compound -chlorotoluene from the FTIR and FT Raman spectra.

The equilibrium geometries, harmonic frequencies and FTIR spectra of the title

compound were determined and analysed both at HF and B3LYP levels of theory

utilizing 6-311G(d) and 6-311++G(d) basis sets The important points noticed in this

molecule are

It is very fascinating to note that the C-C bond lengths are equal with its

neighbouring pairs (C5-C6, C2-C3/ C4-C5, C3-C4/ C1-C2, C1-C6 ) within the

benzene ring.

The aromatic C-H stretching and bending vibrations are well within the

expected range, which shows that the substitution in the molecule does not

produce any difference in this corresponding frequency range.

When comparing the aromatic CH symmetric and asymmetric vibrations, it is

noted that one of the CH symmetric vibrational mode is greater than that of the

CH asymmetric vibrational mode.

The strong peak at 700 cm-1 in the out-of-plane bending vibration region is

due to four adjacent hydrogen atoms in the benzene ring confirm the mono

substituted nature of the title compound.

The CH2 scissoring vibration which greater than the expected range

approximately by 35 cm-1

shows that it is affected by the skeletal vibration of

the ring.

The skeletal vibrations (C=C and C-C) are within the expected range.

The occurrence of strong band at 1200 cm-1 is due to the valence oscillations

in toluenes and substituted toluenes which very much coincide with the earlier

literature predictions.

The calculated bondlength for C-Cl differs from the earlier literature values

because in this molecule the Cl atom is attached with CH2 group while in the

earlier literatures, it is directly connected with benzene ring.

It is also noted that C-Cl and C-CH2Cl bond lengths are greater than all other

bondlengths in the molecule due to its higher electronegativity which

elongates that particular bond lengths.

The HF/6-311 G(d) and 6-311++ G(d) bond lengths are slightly shorter due to

the neglect of electron correlation, while the B3LYP/6-311 G(d) and 6-311++

G(d) bond lengths are closer to the experimental data due to slightly

exaggerated electron correlation effect.

The strong band appeared around 1200 cm-1 appears due to valence

oscillations in toluenes and substituted toluenes and predicted in the earlier

literatures.

The peak appeared for out-of plane bending is greater than the expected range

due to the presence of CH2Cl in the neighbouring CH moiety.

Comparison between the calculated vibrational frequencies and the

experimental values indicates that both the methods can predict the FTIR and

FT Raman spectra of the title compound well.

By applying the suitable scaling factors with calculated frequencies, the results

of DFT-B3LYP method indicate better fit to experimental ones than ab initio

HF upon evaluation of vibrational frequencies.

Any discrepancy noted between the observed and the calculated frequencies

may be due to the fact that the calculation have been actually done on a single

molecule contrary to the experimental values recorded in the presence of

intermolecular interactions.

The assignments made at higher level of theories and basis sets with

reasonable deviations from the experimental values seem to be consistent.

Fig.4.1. Molecular Structure of -chlorotoluene with numbering of atoms

Fig.4.2. Comparative Graph for C-C and C-Cl bond lengths with HF and DFT

methods of different basis sets

Fig 4.3. Experimental FTIR Spectrum of -chlorotoluene

Fig 4.4. Experimental FT-Raman Spectrum of -chlorotoluene

Fig. 4.5. Calculated IR Spectrum of -chlorotoluene at HF and B3LYP methods

Fig. 4.6. Calculated Raman Spectrum of -chlorotoluene at HF and B3LYP methods

Fig. 4.7. Comparison of frequencies to relative IR intensities at HF and B3LYP with different basis sets

Fig. 4.8. Comparative graph for mulikan charge on individual atom of

-chlorotoluene with HF and DFT for different basis sets

Table 4.1

Optimized Geometrical Structural Parameters (Bond Length, Bond Angle,

Dihedral Angle) of -chlorotoluene

Parameters HF B3LYP

6-311 G(d) 6-311++ G(d) 6-311 G(d) 6-311++ G(d)

Bond length (in )

C1-C2 1.3879 1.3886 1.3984 1.3989

C1-C6 1.3879 1.3886 1.3984 1.3989

C1-C12 1.5003 1.5008 1.4955 1.4961

C2-C3 1.3839 1.3848 1.3916 1.3924

C2-H7 1.076 1.0762 1.0861 1.0861

C3-C4 1.3849 1.3857 1.3938 1.3944

C3-H8 1.0751 1.0753 1.0852 1.0853

C4-C5 1.3849 1.3875 1.3938 1.3944

C4-H9 1.0752 1.0753 1.0852 1.0853

C5-C6 1.3839 1.3848 1.3916 1.3924

C5-H10 1.0751 1.0753 1.0852 1.0853

C6-H11 1.076 1.0762 1.0861 1.0861

C12-H13 1.0769 1.0772 1.0876 1.0878

C12-H14 1.0769 1.0772 1.0876 1.0878

C12-Cl15 1.8133 1.8118 1.8431 1.841

Bond angle (in degrees)

C2-C1-C6 119.0871 119.0533 118.9905 118.9605

C2-C1-C12 120.4556 120.4724 120.5041 120.5193

C6-C1-C12 120.4553 120.4721 120.5042 120.5193

C1-C2-C3 120.5253 120.5494 120.5525 120.5753

C1-C2-H7 119.7612 119.7678 119.5835 119.5922

C3-C2-H7 119.713 119.6823 119.8634 119.8321

C2-C3-C4 120.0376 120.0414 120.039 120.0412

C2-C3-H8 119.8405 119.8349 119.861 119.8548

C4-C3-H8 120.1218 120.1237 120.0999 120.1039

C3-C4-C5 119.787 119.7651 119.8266 119.8064

C3-C4-H9 120.1065 120.1174 120.0867 120.0968

C5-C4-H9 120.1065 120.1174 120.0867 120.0968

C4-C5-C6 120.0376 120.0414 120.039 120.0412

C4-C5-H10 120.1219 120.1236 120.0999 120.1039

C6-C5-H10 119.8405 119.8349 119.861 119.8548

C1-C6-C5 120.5253 120.5495 120.5524 120.5753

C1-C6-H11 119.7611 119.7678 119.5836 119.5921

C5-C6-H11 119.7131 119.6824 119.8634 119.8321

C1-C12-H13 111.9245 111.88 112.3129 112.2848

C1-C12-H14 111.9245 111.8801 112.3129 112.2848

C1-C12-Cl15 112.3705 112.3538 112.3634 112.2993

H13-C12-C14 109.2422 109.143 109.4639 109.3786

H13-C12-Cl15 105.4911 105.6003 104.9427 105.0531

H14-C12-Cl15 105.4909 105.6002 104.9427 105.0531

Dihedral Angle

C6-C1-C2-C3 0.0203 -0.0346 0.0301 0.0153

C6-C1-C2-H7 -179.7384 -179.804 -179.6886 -179.7367

C12-C1-C2-C3 -179.4645 -179.4935 -179.5671 -179.6549

C12-C1-C2-H7 0.7768 0.7371 0.7142 0.5931

C2-C1-C6-C5 -0.0203 0.0346 -0.0301 -0.0153

C2-C1-C6-H11 179.7384 179.804 179.6886 179.7367

C12-C1-C6-C5 179.4645 179.4935 179.5671 179.6549

C12-C1-C6-H11 -0.7768 -0.7371 -0.7142 -0.5931

C2-C1-C12-H13 28.2274 28.3131 27.8454 27.9601

C2-C1-C12-H14 151.2488 151.1392 151.7461 151.7047

C2-C1-C12-Cl15 -90.262 -90.2738 -90.2042 -90.1676

C6-C1-C12-H13 -151.2503 -151.138 -151.7457 -151.7048

C6-C1-C12-H14 -28.2289 -28.3119 -27.8449 -27.9603

C6-C1-C12-Cl15 90.2603 90.275 90.2047 90.1674

C1-C2-C3-C4 0.0058 0.0149 -0.0114 -0.0211

C1-C2-C3-H8 179.9376 179.9321 179.8883 179.8669

H7-C2-C3-C4 179.7646 179.7846 179.7065 179.7303

H7-C2-C3-H8 -0.3035 -0.2982 -0.3937 -0.3817

C2-C3-C4-C5 -0.0321 0.0052 -0.0077 0.0267

C2-C3-C4-H9 179.9241 179.9142 179.926 179.9333

H8-C3-C4-C5 -179.9637 -179.9117 -179.9072 -179.8611

H8-C3-C4-H9 -0.0076 -0.0028 0.0265 0.0455

C3-C4-C5-C6 0.0321 -0.0052 0.0077 -0.0267

C3-C4-C5-H10 179.9637 179.9117 179.9072 179.8611

H9-C4-C5-C6 -179.9241 -179.9142 -179.9261 -179.9333

H9-C4-C5-H10 0.0076 0.0028 -0.0265 -0.0455

C4-C5-C6-C1 -0.0058 -0.0149 0.0115 0.0211

C4-C5-C6-H11 -179.7646 -179.7845 -179.7065 -179.7303

H10-C5-C6-C1 -179.9376 -179.9321 -179.8883 -179.8669

H10-C5-C6-H11 0.3035 0.2982 0.3937 0.3817

Table 4.2

Experimental and calculated HF/6-311G(d) level vibrational frequencies (cm-1

) , IR Intensity (KM Mol-1

) , Raman Activity (amu-1),

Raman depolarization ratios and reduced masses (amu), force constant (m dyne ) of -chlorotoluene

Sl.

No.

Symmetry

Species

Experimental

frequency Unscaled Scaled

IIR SRa Dep.

Ratio K

Vibrational

Assignments FT - IR FT-Raman Abs Rel Abs Rel

1. A 3100 (w)

3368 3099 1 2 6 2 0.8750 4.1142 0.0041 CH

2. A 3095 (s)

3357 3088 2 2 8 3 0.8626 6.9246 0.0607 CH

3. A 3080 (s)

3346 3078 2 2 2 1 0.5999 5.6960 0.2943 CH

4. A

3070 (s) 3342 3075 1 1 0 0 0.8750 2.2629 0.1668 CH

5. A 3040 (s)

3335 3068 0 0 0 0 0.8750 2.8830 0.3476 CH

6. A

3010 (m) 3332 3015 1 1 5 2 0.5897 3.9506 0.6284 CH of CH2Cl

7. A 2980 (m)

3280 2968 16 17 3 1 0.7716 5.1045 1.1305 CH of CH2Cl

8. A 1605 (w)

1801 1630 0 0 5 2 0.8750 6.3169 1.7186 C=C

9. A

1600 (s) 1776 1607 87 94 30 11 0.6188 5.2753 1.6899 C=C

10. A 1590 (w)

1662 1504 92 100 4 1 0.6640 1.6315 0.5730 C=C

11. A 1500 (s)

1631 1476 9 10 9 3 0.8486 2.2391 0.9667 CH2

12. A 1460 (s)

1612 1459 13 14 9 3 0.6138 3.6764 1.6860 C-C

13. A 1390 (w)

1480 1339 0 0 0 0 0.8750 1.2499 0.6583 C-C

14. A 1320 (m)

1441 1304 0 0 1 0 0.8750 1.5819 0.9183 C-C

15. A 1270 (s)

1356 1227 1 1 1 0 0.5901 1.4273 0.8977 CH2

16. A

1210 (s) 1322 1196 0 0 31 11 0.5451 6.2005 4.3131 C-CH2Cl

17. A 1200 (s)

1295 1172 0 0 0 0 0.8750 1.3716 0.9579 CH

18. A 1180 (w)

1286 1164 0 0 0 0 0.7123 1.3214 0.9620 CH

19. A

1160 (w) 1198 1084 1 1 9 3 0.5448 2.2865 1.6961 t CH2

20. A 1070 (s)

1170 1059 1 1 9 3 0.8750 1.9706 1.5947 CH

21. A

1030 (s) 1122 1015 5 5 2 1 0.8750 1.9322 1.6339 CH

22. A 1020 (s)

1112 1006 1 1 7 2 0.8750 1.0854 1.0569 CH (Ring def)

23. A

1000 (s) 1089 986 0 0 2 1 0.8031 1.1659 1.1518 CH

24. A

990 (w) 1087 984 7 7 24 9 0.5800 2.7295 2.9139 CH

25. A 960 (w)

1033 935 0 0 2 1 0.8750 1.4361 1.5548 CH

26. A 910 (w)

993 899 71 77 22 8 0.7543 1.2426 1.5200 CH2

27. A 810 (s)

945 855 1 1 0 0 0.8750 1.2865 1.6606 CH

28. A 800 (s)

882 798 12 13 0 0 0.8750 2.1264 3.2554 C-CH2

29. A 770 (s) 770 (s) 856 775 2 2 9 3 0.8739 1.1127 1.7434 C-CH2

30. A

700 (s) 772 699 9 10 0 0 0.6690 2.2101 3.5976 CH

31. A 690 (s)

737 667 1 1 6 2 0.8750 5.2036 9.6743 C-Cl of CH2Cl

32. A 610 (w)

680 615 0 0 48 17 0.7840 5.1960 9.9341 CH

33. A 560 (s)

613 555 26 28 85 30 1.2723 1.0592 6.7153 C-CH2Cl

34. A

480 (s) 520 471 5 5 14 5 0.7140 1.0867 7.1079 C- Cl of CH2 Cl

35. A 460 (s)

452 409 0 0 49 17 0.8750 1.0943 7.1702 CCC

36. A

330 (s) 354 320 7 8 108 38 0.8750 1.1074 7.2858 CCC

37. A 270 (s)

296 268 18 20 105 37 0.7900 1.0927 7.2090 C-CH2

38. A 120 (s)

122 110 55 60 16 6 0.8750 1.0961 7.2789 C-Cl of CH2Cl

39. A -

41 37 22 24 281 100 0.5654 1.0990 7.3464 C- CH2Cl

Scale factor of 0.905 for calculated wavenumbers lower than 1700 cm-1

and the scale factor of 0.92 for larger wavenumbers

w weak, m medium, s strongReduced mass, K Force Constant, - Stretching, - In-plane-bending, - Out-of-plane bending,-

Scissoring, - Wagging, - Rocking,t- Twisting, IIR - IR Intensity, SRa - Raman activity

Table 4.3

Experimental and calculated HF/6-311++G(d) level vibrational frequencies (cm-1

) , IR Intensity (KM Mol-1

) , Raman Activity

(amu-1), Raman depolarization ratios and reduced masses (amu), force constant (m dyne ) of -chlorotoluene

Sl.

No.

Symmetry

Species

Experimental

frequency Unscaled Scaled

IIR SRa Dep.

Ratio K

Vibrational

Assignments FT - IR

FT-

Raman Abs Rel Abs Rel

1. A 3100 (w)

3365 3095 18 17 265 100 0.5676 1.0990 7.3297 CH

2. A 3095 (s)

3354 3085 47 44 14 5 0.8750 1.0961 7.2634 CH

3. A 3080 (s)

3343 3076 16 15 95 36 0.7776 1.0927 7.1959 CH

4. A

3070 (s) 3338 3071 5 5 101 38 0.8750 1.1061 7.2604 CH

5. A 3040 (s)

3331 3065 0 0 41 15 0.8750 1.0955 7.1629 CH

6. A

3010 (m) 3329 3012 4 4 13 5 0.7161 1.0868 7.0949 CH of CH2Cl

7. A 2980 (m)

3277 2966 22 21 83 31 0.5290 1.0593 6.7023 CH of CH2Cl

8. A 1605 (w)

1797 1626 0 0 53 20 0.8090 5.1787 9.8491 C=C

9. A

1600 (s) 1772 1603 0 0 9 3 0.8750 5.1806 9.5791 C=C

10. A 1590 (w)

1659 1501 7 7 0 0 0.8142 2.1997 3.5666 C=C

11. A 1500 (s)

1631 1476 2 2 8 3 0.8711 1.1114 1.7415 CH2

12. A 1460 (s)

1609 1456 10 9 0 0 0.8750 2.1105 3.2174 C-C

13. A 1390 (w)

1479 1339 1 1 0 0 0.8750 1.2874 1.6592 C-C

14. A 1320 (m)

1438 1301 69 65 21 8 0.6998 1.2514 1.5240 C-C

15. A 1270 (s)

1355 1226 0 0 2 1 0.8750 1.4540 1.5729 CH2

16. A

1210 (s) 1321 1195 6 6 29 11 0.5480 2.6880 2.7629 C-CH2Cl

17. A 1200 (s)

1294 1171 0 0 2 1 0.8136 1.1704 1.1541 CH

18. A 1180 (w)

1284 1162 0 0 5 2 0.8750 1.0864 1.0559 CH

19. A

1160 (w) 1198 1084 4 4 2 1 0.8750 1.9800 1.6751 t CH2

20. A 1070 (s)

1170 1059 1 1 1 0 0.8750 1.9082 1.5401 CH

21. A

1030 (s) 1120 1014 2 2 11 4 0.5131 2.3031 1.7033 CH

22. A 1020 (s)

1115 1009 0 0 0 0 0.6277 1.3326 0.9764 CH (Ring def)

23. A

1000 (s) 1097 992 0 0 0 0 0.8750 1.3796 0.9776 CH

24. A

990 (w) 1085 982 0 0 43 16 0.5175 6.1473 4.2668 CH

25. A 960 (w)

1038 939 1 1 2 1 0.5126 1.4488 0.9194 CH

26. A 910 (w)

992 898 0 0 1 0 0.8750 1.5833 0.9187 CH2

27. A 810 (s)

946 856 0 0 1 0 0.8750 1.2497 0.6586 CH

28. A 800 (s)

883 799 14 13 11 4 0.5358 3.3922 1.5569 C-CH2

29. A 770 (s) 770 (s) 859 777 11 10 11 4 0.8492 2.3782 1.0341 C-CH2

30. A

700 (s) 772 699 105 100 4 2 0.5930 1.5936 0.5601 CH

31. A 690 (s)

741 671 75 72 27 10 0.6021 5.2994 1.7140 C-Cl of CH2Cl

32. A 610 (w)

678 614 0 0 5 2 0.8750 6.3188 1.7128 CH

33. A 560 (s)

613 554 15 14 3 1 0.7826 5.0214 1.1106 C-CH2Cl

34. A

480 (s) 520 471 1 1 4 2 0.5976 3.8987 0.6222 C- Cl of CH2 Cl

35. A 460 (s)

453 410 0 0 0 0 0.8750 2.8490 0.3444 CCC

36. A

330 (s) 352 319 1 1 0 0 0.8750 2.2617 0.1653 CCC

37. A 270 (s)

296 268 2 2 3 1 0.5705 5.6719 0.2936 C-CH2

38. A 120 (s)

123 111 2 2 5 2 0.8449 6.9098 0.0618 C-Cl of CH2Cl

39. A -

42 38 2 1 4 1 0.8750 4.1112 0.0042 C- CH2Cl

Scale factor of 0.905 for calculated wavenumbers lower than 1700 cm-1

and the scale factor of 0.92 for larger wavenumbers.

w weak, m medium, s strong,Reduced mass, K Force Constant, - Stretching, - In-plane-bending, - Out-of-plane bending,-

Scissoring, - Wagging, - Rocking,t- Twisting, IIR - IR Intensity, SRa - Raman activity

Table 4.4

Experimental and calculated B3LYP/6-311G(d) level vibrational frequencies (cm-1

) , IR Intensity (KM Mol-1

) , Raman Activity

(amu-1), Raman depolarization ratios and reduced masses (amu), force constant (m dyne ) of -chlorotoluene

Sl.

No

Symmetry

Species

Experimental

frequency Unscaled Scaled

IIR SRa Dep.

Ratio K

Vibrational

Assignments FTIR

FT-

Raman Abs Rel Abs Rel

1. A 3100 (w)

3192 3096 1 1 7 2 0.8750 4.1244 0.0048 CH

2. A 3095 (s)

3182 3087 2 2 9 3 0.8607 6.9101 0.0488 CH

3. A 3080 (s)

3173 3078 3 3 3 1 0.6076 5.7532 0.2485 CH

4. A

3070 (s) 3165 3070 1 1 0 0 0.8750 2.2375 0.1439 CH

5. A 3040 (s)

3161 3066 0 0 0 0 0.8750 2.9014 0.2927 CH

6. A

3010 (m) 3160 3018 1 1 7 2 0.5992 3.9404 0.5314 CH of CH2Cl

7. A 2980 (m)

3103 3010 20 21 6 2 0.7096 5.4113 1.0287 CH of CH2Cl

8. A 1605 (w)

1653 1620 0 0 5 2 0.8750 6.3500 1.5135 C=C

9. A

1600 (s) 1633 1600 98 100 54 18 0.6081 4.8053 1.2360 C=C10. A 1590 (w)

1536 1505 53 54 0 0 0.7425 1.6156 0.4781 C=C

11. A 1500 (s)

1503 1473 9 9 6 2 0.7469 2.2142 0.7958 CH2

12. A 1460 (s)

1494 1464 10 11 10 3 0.7476 4.3933 1.7646 C-C

13. A 1390 (w)

1368 1341 0 0 1 0 0.8750 1.2512 0.5310 C-C

14. A 1320 (m)

1345 1318 0 0 1 0 0.8750 1.5547 0.7757 C-C

15. A 1270 (s)

1311 1285 1 1 1 0 0.6505 1.4361 0.7235 CH2

16. A

1210 (s) 1238 1213 0 0 0 0 0.8750 1.3667 0.7462 C-CH2Cl

17. A 1200 (s)

1208 1184 0 0 0 0 0.6035 1.2869 0.7484 CH

18. A 1180 (w)

1190 1166 0 1 29 9 0.5487 6.2948 3.8640 CH

19. A

1160 (w) 1184 1160 2 2 12 4 0.5482 2.2099 1.4405 t CH2

20. A 1070 (s)

1107 1085 6 7 0 0 0.8750 1.5519 1.1196 CH

21. A

1030 (s) 1052 1031 1 1 1 0 0.8750 1.1451 0.9463 CH

22. A 1020 (s)

1021 1001 0 0 8 3 0.8750 1.0804 0.9014 CH (Ring def)

23. A

1000 (s) 993 973 0 0 4 1 0.7053 1.1367 0.9782 CH

24. A

990 (w) 963 944 14 14 58 19 0.6090 3.0918 2.7912 CH

25. A 960 (w)

925 907 49 50 37 12 0.7668 1.1953 1.2110 CH

26. A 910 (w)

920 902 0 0 2 1 0.8750 4.8211 5.1380 CH2

27. A 810 (s)

849 832 1 1 0 0 0.8750 1.2959 1.4281 CH

28. A 800 (s)

826 809 9 10 1 0 0.8750 2.1966 2.8898 C-CH2

29. A 770 (s) 770 (s) 781 765 4 4 8 3 0.8726 1.1183 1.4894 C-CH2

30. A

700 (s) 709 695 5 5 3 1 0.6479 2.2289 3.0989 CH

31. A 690 (s)

661 648 0 0 4 1 0.8750 5.3981 8.4796 C-Cl of CH2Cl

32. A 610 (w)

637 624 0 0 66 21 0.7552 5.4551 8.7794 CH

33. A 560 (s)

568 557 20 20 97 31 0.5329 1.0578 6.0026 C-CH2Cl

34. A

480 (s) 478 468 4 4 13 4 0.6708 1.0859 6.3906 C- Cl of CH2 Cl

35. A 460 (s)

414 406 1 1 21 7 0.8750 1.1036 6.4970 CCC

36. A

330 (s) 330 323 6 6 139 45 0.8750 1.0957 6.4659 CCC

37. A 270 (s)

271 266 13 13 117 38 0.8019 1.0908 6.4685 C-CH2

38. A 120 (s)

109 107 42 43 26 9 0.8750 1.0942 6.5287 C-Cl of CH2Cl

39. A -

44 43 19 19 307 100 0.5624 1.0978 6.5924 C- CH2Cl

Scale factor of 0.98 for calculated wavenumbers lower than 1700 cm-1

and the scale factor of 0.97 for larger wavenumbers.

w weak, m medium, s strongReduced mass, K Force Constant, - Stretching, - In-plane-bending, - Out-of-plane bending,-

Scissoring, - Wagging, - Rocking,t- Twisting, IIR - IR Intensity, SRa - Raman activity

Table 4.5

Experimental and calculated B3LYP/6-311++G(d) level vibrational frequencies (cm-1

) , IR Intensity (KM Mol-1

) , Raman Activity

(amu-1), Raman depolarization ratios and reduced masses (amu), force constant (m dyne ) of -chlorotoluene

Sl.

No.

Symmetry

Species

Experimental

frequency Unscaled Scaled

IIR SRa Dep.

Ratio K

Vibrational

Assignments FT - IR

FT-

Raman Abs Rel Abs Rel

1. A 3100 (w)

3190 3094 16 17 304 100 0.5596 1.0978 6.5817 CH

2. A 3095 (s)

3180 3085 36 38 24 8 0.8750 1.0942 6.5188 CH

3. A 3080 (s)

3170 3075 11 12 108 36 0.7876 1.0908 6.4604 CH

4. A

3070 (s) 3162 3067 4 4 126 42 0.8750 1.0928 6.4380 CH

5. A 3040 (s)

3158 3064 4 4 12 4 0.6664 1.0860 6.3825 CH

6. A

3010 (m) 3158 3016 1 1 22 7 0.8750 1.1065 6.5013 CH of CH2Cl

7. A 2980 (m)

3101 3008 17 18 99 32 0.5248 1.0579 5.9926 CH of CH2Cl

8. A 1605 (w)

1649 1616 0 0 71 23 0.7749 5.4453 8.7274 C=C

9. A

1600 (s) 1629 1597 0 0 7 2 0.8750 5.3881 8.4281 C=C

10. A 1590 (w)

1533 1503 4 4 3 1 0.6821 2.2215 3.0779 C=C

11. A 1500 (s)

1502 1472 4 4 7 2 0.8743 1.1175 1.4863 CH2

12. A 1460 (s)

1491 1462 7 8 1 0 0.8750 2.1831 2.8610 C-C

13. A 1390 (w)

1366 1339 1 1 0 0 0.8750 1.2972 1.4269 C-C

14. A 1320 (m)

1345 1318 0 0 2 1 0.8750 4.8856 5.2054 C-C

15. A 1270 (s)

1308 1281 48 50 36 12 0.7261 1.2041 1.2130 CH2

16. A

1210 (s) 1237 1212 12 13 61 20 0.5831 3.0434 2.7428 C-CH2Cl

17. A 1200 (s)

1208 1184 0 0 3 1 0.6763 1.1381 0.9780 CH

18. A 1180 (w)

1189 1165 0 0 6 2 0.8750 1.0817 0.9006 CH

19. A

1160 (w) 1183 1160 0 0 1 0 0.8750 1.1396 0.9401 t CH2

20. A 1070 (s)

1105 1083 7 7 0 0 0.8750 1.5574 1.1209 CH

21. A

1030 (s) 1050 1029 2 3 15 5 0.5211 2.2193 1.4429 CH

22. A 1020 (s)

1020 1000 0 0 39 13 0.5236 6.2748 3.8468 CH (Ring def)

23. A

1000 (s) 996 976 0 0 1 0 0.5618 1.3015 0.7602 CH

24. A

990 (w) 971 952 0 0 0 0 0.8750 1.3783 0.7662 CH

25. A 960 (w)

929 910 1 1 1 0 0.5191 1.4632 0.7436 CH

26. A 910 (w)

919 901 0 0 1 0 0.8750 1.5582 0.7762 CH2

27. A 810 (s)

848 831 0 0 0 0 0.8750 1.2506 0.5303 CH

28. A 800 (s)

825 809 10 10 11 3 0.6469 4.2877 1.7199 C-CH2

29. A 770 (s) 770 (s) 785 769 10 10 11 3 0.7278 2.2406 0.8130 C-CH2

30. A

700 (s) 708 694 58 61 1 0 0.6157 1.5850 0.4686 CH

31. A 690 (s)

664 651 95 100 54 18 0.6173 4.7977 1.2471 C-Cl of CH2Cl

32. A 610 (w)

636 624 0 0 5 2 0.8750 6.3251 1.5096 CH

33. A 560 (s)

568 556 18 19 5 2 0.7086 5.3048 1.0077 C-CH2Cl

34. A

480 (s) 480 470 1 1 6 2 0.6015 3.8608 0.5236 C- Cl of CH2 Cl

35. A 460 (s)

414 406 0 0 0 0 0.8750 2.8521 0.2883 CCC

36. A

330 (s) 329 322 1 1 0 0 0.8750 2.2364 0.1424 CCC

37. A 270 (s)

271 266 3 3 4 1 0.5803 5.7194 0.2478 C-CH2

38. A 120 (s)

111 108 2 2 6 2 0.8470 6.9023 0.0498 C-Cl of CH2Cl

39. A -

43 42 1 1 5 2 0.8750 4.1162 0.0046 C- CH2Cl

Scale factor of 0.98 for calculated wavenumbers lower than 1700 cm-1

and the scale factor of 0.97 for larger wavenumbers.

w weak, m medium, s strongReduced mass, K Force Constant, - Stretching, - In-plane-bending, - Out-of-plane bending,-

Scissoring, - Wagging, - Rocking,t- Twisting, IIR - IR Intensity, SRa - Raman activity

Table 4.6

Mulliken atomic charges of -chlorotoluene performed at HF, B3LYP methods

with 6-311G(d) and 6-311++G(d) basis sets

Atoms

Atomic Charges

HF B3LYP

6-311 G(d) 6-311++ G(d) 6-311 G(d) 6-311 ++G(d)

C1 0.059 1.944 0.085 1.175

C2 -0.222 -0.637 -0.183 -0.607

C3 -0.208 -0.525 -0.194 -0.473

C4 -0.217 -0.539 -0.183 -0.346

C5 -0.208 -0.525 -0.194 -0.473

C6 -0.222 -0.637 -0.183 -0.607

H7 0.223 0.31 0.2 0.256

H8 0.223 0.321 0.197 0.263

H9 0.221 0.291 0.195 0.24

H10 0.223 0.321 0.197 0.263

H11 0.223 0.31 0.2 0.256

C12 -0.513 -0.875 -0.572 -0.811

H13 0.272 0.267 0.274 0.266

H14 0.272 0.267 0.274 0.266

Cl15 -0.126 -0.212 -0.11 -0.209

Table 4.7

Theoretically computed Zero point vibrational energy (kcal mol-1

),

rotational constants (GHz), thermal energy (kcal mol-1

), molar capacity at

constant volume (cal mol-1

Kelvin-1

), entropy (cal mol-1

Kelvin-1

) and dipole

moment (Debye)

Parameter

HF B3LYP

6-311 G(d) 6-311++ G(d) 6-311 G(d) 6-311++ G(d)

Zero Point Vibrational

Energy 80.19313 80.15385 74.99305 74.9588

Rotational Constants

4.27445 4.27204 4.19811 4.19422

0.98618 0.98587 0.97436 0.97484

0.88422 0.88389 0.87416 0.87457

Energy 84.291 84.248 79.345 79.308

Molar capacity at

constant volume 23.746 23.728 25.803 25.786

Entropy 83.882 83.822 85.197 85.216

Dipole moment (Debyes) 2.5717 2.4207 2.6648 2.565