Experimantal (FT-IR and FT-Raman spectra) and theoretical (ab initio HF and DFT) study of 2-Chloro-5-Methylaniline (original) (raw)
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Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2009
In this work, the experimental and theoretical vibrational spectra of 2-chloro-4-methylaniline (2Cl4MA, C 7 H 8 NCl) were studied. FT-IR and FT-Raman spectra of 2Cl4MA in the liquid phase have been recorded in the region 4000-400 cm −1 and 3500-50 cm −1 , respectively. The structural and spectroscopic data of the molecule in the ground state have been calculated by using Hartree-Fock (HF) and density functional method (B3LYP) with the 6-31G(d), 6-31G(d,p), 6-31+G(d,p), 6-31++G(d,p) and 6-311G(d), 6-311G(d,p), 6-311+G(d,p), 6-311++G(d,p) basis sets. The vibrational frequencies have been calculated and scaled values have been compared with experimental FT-IR and FT-Raman spectra. The observed and calculated frequencies are found to be in good agreement. The complete assignments were performed on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method. The DFT-B3LYP/6-311++G(d,p) calculations have been found more reliable than the ab initio HF/6-311++G(d,p) calculations for the vibrational study of 2Cl4MA. The optimized geometric parameters (bond lengths and bond angles) were compared with experimental values of aniline and p-methylaniline molecules.
Molecular Physics, 2009
In this work, the experimental and theoretical UV, NMR and vibrational spectra of 2-chloro-6-methylaniline (2-Cl-6-MA, C7H8NCl) were studied. The ultraviolet absorption spectra of compound that dissolved in ethanol were examined in the range of 200–400 nm. The 1H, 13C and DEPT NMR spectra of the compound were recorded. FT-IR and FT-Raman spectra of 2-Cl-6-MA in the liquid phase were recorded in the region 4000–400 cm−1 and 3500–50 cm−1, respectively. The structural and spectroscopic data of the molecule in the ground state were calculated using density functional theory (DFT) employing B3LYP exchange correlation and the 6-311++G(d,p) basis set. The vibrational frequencies were calculated and scaled values were compared with experimental FT-IR and FT-Raman spectra. The observed and calculated frequencies were found to be in good agreement. The complete assignments were performed on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method. Isotropic chemical shifts were calculated using the gauge-invariant atomic orbital (GIAO) method. Comparison of the calculated NMR chemical shifts and absorption wavelengths with the experimental values revealed that DFT method produces good results.
FT-IR, FT-Raman, NMR spectra and DFT calculations on 4-chloro-N-methylaniline
Spectrochimica Acta Part A-molecular and Biomolecular Spectroscopy, 2010
In this work, the vibrational spectral analysis was carried out by using FT-IR and FT-Raman spectroscopy in the range 400–4000 and 50–3500 cm−1 respectively, for the title molecule. The structural and spectroscopic data of the molecule in the ground state were calculated by using density functional method using 6-311++G(d,p) basis set. The vibrational frequencies were calculated and scaled values were compared with experimental FT-IR and FT-Raman spectra. The observed and calculated frequencies are found to be in good agreement. The complete assignments of all the vibrational mode were performed on the basis of the total energy distributions (TED). 13C and 1H NMR chemical shifts results were given and are in agreement with the corresponding experimental values. The theoretically constructed FT-IR and FT-Raman spectra exactly coincides with experimental one.
Journal of Physical Organic Chemistry
In this work, the experimental and theoretical vibrational spectra of N1-methyl-2-chloroaniline (C 7 H 8 NCl) were studied. FT-IR and FT-Raman spectra of the title molecule in the liquid phase were recorded in the region 4000-400 cm S1 and 3500-50 cm S1 , respectively. The structural and spectroscopic data of the molecule in the ground state were calculated by using density functional method (B3LYP) with the 6-311RRG(d,p) basis set. The vibrational frequencies were calculated and scaled values were compared with experimental FT-IR and FT-Raman spectra. The observed and calculated frequencies are found to be in good agreement. The complete assignments were performed on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method. 13 C and 1 H NMR chemical shifts results were compared with the experimental values. The optimized geometric parameters (bond lengths and bond angles) were given and are in agreement with the corresponding experimental values of aniline and p-methyl aniline.
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2010
Fourier-transform Raman and infrared spectra of 2-nitroanisole are recorded (4000-100 cm −1 ) and interpreted by comparison with respective theoretical spectra calculated using HF and DFT method. The geometrical parameters with C S symmetry, harmonic vibrational frequencies, infrared and Raman scattering intensities are determined using HF/6-311++G (d, p), B3LYP/6-311+G (d, p), B3LYP/6-311++G (d, p) and B3PW91/6-311++G (d, p) level of theories. A detailed vibrational spectral analysis has been carried out and assignments of the observed fundamental bands have been proposed on the basis of peak positions and relative intensities. The results of the calculations have been used to simulate IR and Raman spectra for the molecule that showed good agreement with the observed spectra. The SQM method, which implies multiple scaling of the DFT force fields has been shown superior to the uniform scaling approach. The vibrational frequencies and the infrared intensities of the C-H modes involved in back-donation and conjugation are also investigated.
Vibrational Spectral Investigations, NLO and Homo LUMO Analysis of 4-Chloro-2, 6-Dibromoaniline
Introduction Aniline and its derivatives have been widely used as starting materials in a vast amount of chemicals, pharmaceuticals, dyes, electro-optical and many other industrial processes [1-4]. The conducting polymer of aniline, namely, poly aniline is used in microelectronic devices as diodes and transistors [5-8]. Particularly, aniline and its derivatives are used in the production of dyes, pesticides and antioxidants. Consideration of these factors leads to undertake the detailed spectral investigation of 4-chloro-2, 6-dibromoaniline (CDBA). The aim of this work is to carry out an experimental and theoretical study on these compounds with the methods of quantum chemistry, in order to have a better understanding of its vibrational properties. However, for a proper understanding of IR and Raman spectra, reliable assignments of all vibrational bands are essential. Recently, computational methods based on density functional theory are being widely used. These methods predict a relatively accurate molecular structure and vibrational spectra with moderate computational effort. In particular, for polyatomic molecules, the DFT methods lead to the prediction of more accurate molecular structure and vibrational frequencies than the conventional ab initio restricted Hartree-Fock (HF) and Moller-Plesset second order perturbation theory (MP2) calculations [9-12]. To the best of our knowledge, there is no theoretical calculation to understand the structure and the fundamental vibrational frequencies of CDBA and PFA. This study is made to present a full description of the vibrational spectra of the title compounds, using ab initio HF and DFT (B3LYP) with 6-31+G(d,p) to obtain the geometries, vibrational frequencies, IR intensities and Raman activities. The atomic charges, distribution of electron density (ED) in various bonding and antibonding orbitals and stabilisation
Infrared, Raman spectra and DFT calculations of chlorine substituted anilines
Vibrational Spectroscopy, 2006
The infrared and Raman spectra of chlorine substituted anilines (2,5-dichloroaniline, 2,4-dichloroaniline and 3,5-dichloroaniline) have been measured in the region of 4000-600 cm À1 . FAR infrared spectrum of 2,5-dichloroaniline has been also presented. Vibrational frequencies, rotational constants and energies of these molecules have also been calculated by means of quantum chemical calculations using density functional theory and Restricted Hartree-Fock method with 6-31+G* and 6-311++G** basis sets. An assignment of normal modes of vibration to the observed frequencies has been based on these calculations. Non-co-planarity of amino group with respect to the phenyl ring has been investigated. To test the reliability of the computational methods, a series of calculations has been done for aniline to substituted anilines using different basis sets. #
Spectroscopic (FT-IR, FT-Raman and NMR) and computational studies on 3-methoxyaniline
Journal of Molecular Structure, 2014
h i g h l i g h t s Molecular structure of 3,5-difluorophenylboronic acid conformers and its dimer structure were investigated. Spectroscopic properties of 3,5-difluorophenylboronic acid were examined. The complete assignments were performed on the basis of the total energy distribution (TED). TDOS, PDOS and OPDOS were investigated.