Theoretical and experimental vibrational property of 1,3,4,6-tetramethylpiperazine-2,5-dione

<p>1,3,4,6-tetramethylpiperazine-2,5-dione was synthesized, and the crystal structure was characterized by single-crystal X-ray diffraction method, vibrational spectral measurements were obtained by Fourier transform infrared spectroscopy and Fourier transform Raman spectroscopy. The measurements agree well with the calculated geometrical structure and harmonic vibrational wavenumbers (using<i>ab initio</i> and density functional theory Becke’s three parameters hybrid method with the Lee, Yang, and Parr non-local functions methods with 6-311G and 6-311G** basis sets).</p>