Experimental and Theoretical Investigation and NBO Analysis on the Structure of Pregabalin

A systematic vibrational spectroscopic assignment and analysis of pregabalin has been carried out by using FTIR, FT-Raman spectral data. The vibrational analysis were aided by electronic structure calculations-hybrid density functional methods (B3LYP) performed with 631G(d,p) basis set. Molecular equilibrium geometries, electronic energies, natural bond order analysis, IR intensities, and harmonic vibrational frequencies have been computed. The assignments proposed based on the experimental IR and Raman spectra have been reviewed and selected assignment of the observed spectra have been proposed. The electronic properties, such as HOMO and LUMO energies and λmax were determined by time-dependent DFT (TD-DFT) method. The thermodynamic functions of the title molecule were also performed using DFT method.