Infrared and Raman spectra, conformational stability and vibrational assignment of 1-formylpiperazine

Infrared and Raman spectra of 1-formylpiperazine (1-fp) have been recorded in the region of 4000-50 cm(-1). The conformational analysis, optimized geometric parameters, normal mode frequencies and corresponding vibrational assignments of 1-fp (C5H10N2O) have been examined by means of Becke-3-Lee-Yang-Parr (B3LYP) density functional theory (DFT) method together with 6-31++G(d,p) basis set. Furthermore, reliable conformational investigation and vibrational assignments have been made by the potential energy surface (PES) and potential energy distribution (PED) analyses, respectively. Calculations are carried out with the possible six conformational isomers of 1-fp, both in gas phase and in solution using benzene and methanol. The experimental and theoretical results indicate that B3LYP method provides satisfactory evidence for the prediction vibrational wavenumbers, and the normal chair conformation with equatorial substituents is not preferred due to the steric interaction.