DFT, FT-Raman, and FT-IR investigations of 1-cyclopropylpiperazine

Abstract

FT-IR and FT-Raman spectra of 1-cyclopropylpiperazine (1cppp) are experimentally examined in the range 4000-200 cm(-1). The optimized geometric parameters, conformational equilibria, normal mode frequencies and corresponding vibrational assignments of 1cppp C7H14N2 are theoretically examined by means of B3LYP hybrid density functional theory (DFT) with the 6-31++G(d,p) basis set. Based on the potential energy distribution (PED) reliable vibrational assignments are made and the thermodynamics functions, highest occupied and lowest unoccupied molecular orbitals (HOMO and LUMO) of 1cppp are predicted. Calculations are performed for four different conformations in two point groups of 1cppp in the gas phase. A comparison between the experimental and theoretical results indicates that the B3LYP method is able to provide satisfactory results for the prediction of vibrational frequencies, structural parameters, and assignments. Furthermore, the C (s) (equatorial-equatorial) point group is found as the most stable conformer of 1cppp.