| Abstract: | The molecular structures of fifteen possible 2-thioxanthine(2TX) complexes with one Hg~(2+) and two Cl-ions were fully optimized using density functional theory B3PW91/6-311++G** method. The effective pseudo potential LANL2DZ basis set was used for metal Hg~(2+)ion. The vibrational analysis was also carried out at the same level. The bond lengths, bond angles, zero point energies, Gibbs free energies, thermodynamic energies and relative energies of all the complexes were obtained. The NBO analysis for natural charge and the second order perturbation energy values was carried out for three stable complexes and the IR spectroscopy of the two complexes was assigned to the experimental data. The results show that the 2-thioxanthine complexes with one Hg~(2+) and two Cl-ions were formed and the complexes resulting from the thione tautomer are more stable than that of the thiol ones. The order of three complexes with relative lower energy is 2TX(1,3,7)-Hg~(2+)-2, 2 TX(1,3,7)-Hg~(2+)-1 and 2 TX(1,3,9)-Hg~(2+). The calculated IR spectroscopy of the two complexes agreed with the experimental data. |
