Molecular Structure, Spectroscopic(FT-IR,FT-Raman, NMR,UV), HOMO- LUMO Analysis of 1-Bromo-4-Nitrobenzene by Quantum Computational Methods (original) (raw)

FT-Raman spectra of 1- were recorded in the regions 4000-400 cm -1 and 3500-50 cm -1 , respectively. The fundamental vibrational frequencies and intensities of the vibrational bands were calculated using density functional theory (DFT) with B3LYP method and standard 6-311++G (d, p) basis set combinations. The infrared and Raman spectra were also predicted from the calculated intensities. The vibrational spectra were interpreted with the aid of normal coordinate analysis based on a scaled quantum mechanical force field. Comparison of simulated spectra with the experimental spectra provided important information about the ability of the computational method to describe the vibrational modes. The calculated and observed frequencies are found to be in good agreement. The theoretical UV-Vis spectrum of the compound and the electronic properties, such as HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital) energies were obtained by TD-DFT approach. The 1 H and 13 C nuclear magnetic resonance (NMR) chemical shifts of 1B4NB were calculated using the Guauge Independent Atomic Orbital (GIAO) method. The Mullikan charges of the molecule were computed using DFT calculations. The chemical reactivity and Thermodynamic properties of 1B4NB at different temperatures were also calculated. Information about the size, shape, charge density distribution and site of chemical reactivity of the molecule has been obtained by mapping molecular electron density isosurface with the molecular electrostatic potential.