Ab initio studies on complexes formed by melamine and cyclotrione

Ab initio methods were used to study the binding energies of non-bonded complexes formed by melamine and cyclotrione, with the STO-3G, 3-21G and 6-31G (d) basis sets. The electronic spectra were computed using the INDO/CIS method, and the IR spectra, Raman and NMR spectra with the RHF/6-31G (d) method. It was dem- onstrated that the complexes could be formed because of the negative binding ener- gies, which were changed with the change in the electronic properties of the mono- mers. A red-shift of the first absorptions in the electronic spectra and the vibrational frequencies of the N-H bonds in the IR and Raman spectra of the complexes, com- pared with those of the monomers, occurred; simultaneously, the 1 Ha nd 13 C chemical shifts were altered, due to the non-bonded interaction.