Ab initio studies of molecular structures, conformers and vibrational spectra of heterocyclic organics: I. Nicotinamide and its N-oxide.

摘要: Abstract FTIR spectra of nicotinamide and its N-oxide have been recorded analyzed in the range 400–4000 cm −1 . The stabilities, optimized molecular geometries, APT charges vibrational characteristics for two possible conformers studied theoretically using restricted Hartree–Fock (RHF) density functional theory (DFT) methods. E (trans) are found to be more stable less polar than their respective Z (cis) conformers. Due addition an O atom at N 1 site NA molecule magnitudes atomic on all H sites increase. For molecules, magnitude wagging mode NH 2 group is higher torsion mode, which reverse order as compared that aniline molecule. Most frequencies nearly same N-oxide, however, significant changes noticed IR intensities, Raman activities depolarization ratios bands. frequency ring breathing decrease by 100 cm going NANO both intensity scissoring CON(H ) significantly NA-II conformer NA-I conformer.