Vibrational Spectroscopy, Molecular properties, IR, UV-Visible, NMR Spectra and (HF, DFT) Calculations of Organic Molecule

 

Hadeel K. Mohammed, Adil N. Ayyash

*Department of Physics, College of Science, University of Anbar, Anbar, Iraq.

*Corresponding Author E-mail: adilnameh7878@gmail.com

A theoretical study has allowed of an organic compound, [N-(4-acetylphenyl) carbamothioyl)-2-chloroacetamide]. We use HF and DFT calculations to determine the vibrational modes. The HOMO–LUMO energies lead to estimate the value of energy gap of our compound. After that, we determined all modes of vibrations. The IR, NMR and UV-Visible spectra are determined by HF, DFT methods.

 

 

INTRODUCTION:

The organic compounds have different properties and many applications. many researches dealing with organic compounds have been carried out in the modern few years. Some of this compounds have been studied theoretically and experimentally together [1, 2].

 

Our work put full study on the structure, vibrations, IR, NMR, UV-visible spectra of the [N-(4-acetylphenyl) carbamothioyl)-2-chloroacetamide]. Our compound  is  prepared as shown in Scheme.1 [3].

 

 

Scheme.1 Synthesis of [ N-(4-acetylphenyl) carbamothioyl)-2-chloroacetamide].

 

Vibrational spectra is an important tool for giving data about groups and interactions in structure. The UV–Visible calculations are important to show the energy gap for molecules.  Furthermore, the dipole moment of [N-(4-acetylphenyl) carbamothioyl)-2-chloroacetamide] are studied in this study. We also calculate the electronic properties by two methods. The modes will give us IR spectra theoretically and comparing these with empirical values. NMR shift's studies will explain our calculations.

 

 

 

Computational Concepts:

Our calculations were done by program called Gaussian [4] and help software [5]. For optimization, The structural geometry was done by HF (Hartre - Fock) and DFT (Density Function Theories) depending on B3/LYP [6, 7] functional with 6-311G (d,p) set. From the optimization, modes frequencies, optimized structure, UV–Vis spectra, the dipole moment, frontier molecular orbital have been calculated. We determined also the NMR spectra using HF, DFT methods.

 

RESULTS AND DISCUSSION:

The optimized structure for our molecule is given in Figure. 1. The initial parameters computed by HF, DFT / B3LYP functions with the 6-311G (d,p) basis sets are appeared in tables 1 and 2 respectively.

 

Figure 1. Optimized structure for [N-(4-acetylphenyl) carbamothioyl)-2-chloroacetamide].

 

Table 1. The initial parameters computed by HF

Calculation method	HF
Basis set	6-311G(d,p)
Spin	Singlet
Electronic energy	-1530.273765 Hartree
Dipole moment	9.159443 Debye

 

Table 2. The initial parameters computed by DFT

Calculation method	DFT / B3LYP
Basis set	6-311G(d,p)
Spin	Singlet
Electronic energy	-1535.582410 Hartree
Dipole moment	5.451568 Debye

 

The (LUMO) and (HOMO) represent the ability to accept and donate an electron, respectively. The chemical stability of [N-(4-acetylphenyl) carbamothioyl)-2-chloroacetamide] depend on these orbitals which have strong factor in the optic and electrical parameters, also in quantum mechanics and UV spectrum. The [ N-(4-acetylphenyl) carbamothioyl)-2-chloroacetamide] compound have 374 orbitals, (70 occupied, 114 unoccupied). The energy gap estimated as listed in Table 3. These gaps were found 0.03434 eV using HF method and 0.0345 eV using DFT method.

 

Table 3. The energy gap by two methods

 

As Comparing, we found that HF method and it in good agreement with the DFT method of the [N-(4-acetylphenyl) carbamothioyl)-2-chloroacetamide]. The configurations in energies at two methods (HF and DFT) are shown in Figure 2. The UV–Vis spectra in two methods of studied compound are appeared in Figure 3. The spectra of [N-(4-acetylphenyl) carbamothioyl)-2-chloroacetamide] appear maximum absorption band at 230nm for HF method and in 298 nm for DFT method.

 

Figure 2. Molecular orbital surfaces for the HOMO, LUMO with energy gap in

 

A-                   HF method   B- DFT method.

 

Figure 3. UV-Vis Spectrum of [ N-(4-acetylphenyl) carbamothioyl)-2-chloroacetamide] as calculated by A- HF method B- DFT method.

 

In N-(4-acetylphenyl) carbamothioyl)-2-chloroacetamide] compound 28 atoms and 78 modes show IR spectrum (Figure 4). The fundamental wavenumbers of our molecule have been done by HF and DFT. The calculations are convergence with the empirical results [3]. That due to the anharmonicity factor neglect in this work, or it due to the theoretical results (in gaseous phase) while the empirical (in solid state).

 

The stretching vibration of secondary amine NH group and C-H group was observed. The one important significant band of carbonyl group C=O was appeared as strongly and sharp, whereas the spectrum showed multiple peaks due to aromatic C=C group. Furthermore, different bands were noted in the spectrum which could be attributed to the C=S, C-N, and C-C. However, all of these data are confirmed the designed structure of own compound.

 

 

Figure 4. IR spectra of [N-(4-acetylphenyl) carbamothioyl)-2-chloroacetamide] as calculated by A- HF method B- DFT method.

 

Figure 5. The IR experimental spectrum of [N-(4-acetylphenyl) carbamothioyl)-2-chloroacetamide][3].

For (1H NMR) spectra, the theoretical chemical shifts from tetramethylsilane (TMS) as an standard internal solution were calculated by GIAO method. For our compound, there are various types of proton, two protons of NH group were observed at 9.25 and 5.90 ppm. Other protons of benzene ring signals were recorded in the region 8.20-6.95 ppm while the aliphatic protons peaks at 3.85-2.75 ppm have been appeared. Thus, theoretical chemical shifts for 1HNMR spectra was utilized to characterize the molecular structure, (Figure 6).

 

 

Figure 6. 1H NMR spectra of [N-(4-acetylphenyl) carbamothioyl)-2-chloroacetamide] as calculated by SCF GIAO method by

A- HF method, B- DFT method.

 

 

CONCLUSION:

In present paper, we recorded a calculations and some details of [N-(4-acetylphenyl) carbamothioyl)-2-chloroacetamide]. We recorded the geometrical and spectroscopic details by some functional: HF and DFT/B3-LYP. The calculations of our compound properties are showing 78 modes of frequencies at IR spectrum. A spectroscopic studies were important in IR, UV and NMR spectra and appearing an agreement of theoretical results by our HF and DFT methods.

 

REFERENCES:

1.      Chemla D.S., and Zyss J., Non-linear Optical Properties of Organic Molecular Crystals, vol. 1, 2, Academic Press, London, 1987.

2.      Badan J., Hierle R., Perigaud A., and  Zyss J., in: D.J. Williams (Ed.), Nonlinear Optical Properties of Organic Molecules and Polymeric Materials, American Chemical Symposium Series, vol. 233, American Chemical Society, Washington, DC, 1993.

3.      Khalaf A. Z., PhD Thesis (chimstry), Anbar University, Anbar,Iraq, 2018.

4.      Frisch M. J., Trucks G. W., Schlegel H. B., Scuseria G. E., Robb M. A., Cheeseman J. R., Scalmani G., Barone V., Mennucci B., Petersson G. A., Nakatsuji H., Caricato M., Li, Hratchian H. P., Izmaylov A. F., Bloino J., Zheng G., Sonnenberg J. L., Hada M., Ehara M., Vreven Toyota K., Fukuda R., Hasegawa J. , Ishida M., Nakajima T., Honda Y., Kitao O., Nakai H., T., Montgomery J. A., Peralta J. E., Ogliaro F., Bearpark M., Heyd J. J., Brothers E., Kudin K. N., Staroverov V. N., Kobayashi R., Normand J., Raghavachari K., Rendell A., Burant J. C., Iyengar S., Tomasi S., J., Cossi M., Rega N., Millam J. M., Klene M., J. Knox E., Cross J. B., Bakken V., Adamo C., Jaramillo J., Gomperts R., Stratmann R. E., Yazyev O., Austin A. J., Cammi R., Pomelli C., Ochterski J. W., Martin R. L., Morokuma K., Zakrzewski V. G., Voth G. A., Salvador P., Dannenberg J. J., Dapprich S., Daniels A. D., Farkas Ö., Foresman J. B., Ortiz J. V., Cioslowski J., and Fox D. J., Gaussian, Inc., Wallingford CT, 2009.

5.      Dennington R., Keith T. and Millam J.. GaussView, Version 5 Semichem Inc., Shawnee Mission KS, 2009.

6.      Becke A. D., “Density-functional thermochemistry. III. The role of exact exchange, J. Chem. Phys., 1993, 98 ,5648-52.

7.      Lee C., Yang W., and Parr R. G., “Development of the Colle-Salvetti correlation energy formula into a functional of the electron density,” Phys. Rev., 1988, B, 37 ,785-789.

 

 

 

 

Received on 16.08.2019                    Modified on 30.08.2019

Accepted on 18.09.2019                   ©AJRC All right reserved