Structural, intramolecular hydrogen bonding and vibrational studies on 3-amino-4-methoxy benzamide using density functional theory

Abstract

An extensive theoretical study on the molecular structure and vibrational analysis of 3-amino-4methoxy benzamide (3A4MBA) was undertaken using density functional theoretical (DFT) method. The possibility of formation of intramolecular hydrogen bonding was identified from structural parameter analysis and confirmed with the natural bond orbital (NBO), molecular electrostatic potential (MEP) and natural charge analysis. The harmonic oscillator model of aromaticity (HOMA) index elucidated the impact of hydrogen bonding in the ring. Intramolecular hydrogen bonding energy has been calculated from topological study. The low wavenumber vibrational modes obtained from experimental FT-Raman spectrum also supported the presence of hydrogen bonding. Bands are assigned for vibrational frequencies using DFT/B3LYP/6-311++G** level of theory.

Quantum chemical determination of molecular geometries and spectral investigation of 4-ethoxy-2, 3-difluoro benzamide

“…The quantum chemical calculation reveals the overestimated calculated vibrational modes when compared to the experimental values due to the anharmonicity that can be corrected by introducing scale factors to minimize overall deviation using MOLVIB 7.0 by sundius [20]. The Root Mean Square (RMS) values of IR and Raman wave numbers were evaluated using the following equation [40, 41]. …”