Theorical investigation of the spectroskopic, optic and geometric properties of melamine pthalate molecule

The molecular geometry, the normal mode frequencies and corresponding vibrational assignment of melaminium phthalate (C3H7N6+.C8H5O4-)in the ground state were performed by HF and B3LYP methods using the 6-31G(d) basis set. The optimized bond length numbers and bond angles are in good agreement with the X-ray data. The vibrational spectra of melaminium phthalate which is calculated by HF and B3LYP methods, reproduces vibrational wave numbers with an accuracy which allows reliable vibrational assignments. The title compound has been studied in the4000?100 cm-1 region where the theoretical evaluation and assignment of all observed bands were made.