Semi-empirical calculations were used to characterize the orotic acid structure. The structures optimised using the PM3, AM1, and CNDO methods were compared with the crystallographic data. Orotic acid is a polydentate ligand due to the net charge on the atoms from the functional group. A compound was synthesized by reacting orotic acid with zinc acetate dihydrated in a neutral and non-aqueous media. This compound was characterized by elemental analysis, spectroscopy, and thermal analysis. The orotic acid replaces water molecules from zinc acetate dihydrate and coordinates through an exo-cyclic oxygen. Based on the probable structure, PM3 semi-empirical calculations of the complex of Zn(II) were performed. The semi-empirical calculations suggest that the orotic acid coordinated through C 2 =O group, where acetate groups maintained the bidentate coordination and the Zn-H 3 Or distance is greater than that the Zn-H 2 O distance for the Zn(II) acetate dihydrate.

Different complexes by reacting copper(II) acetate monohydrate with orotic acid and orotate as ligands were prepared. These compounds were characterized by elemental analysis, spectroscopy, and thermal analysis. It is suggested that in both compounds, the Cu 2 (acetate) 4 suffers the break of both acetate groups by a substitution of orotic or orotate ligands, increasing the Cu-Cu distance. It was corroborated by the magnetic moment values of 1.65 and 1.82 B.M for these compounds.The anion orotato(-1) coordinates through the carboxylic acid and the orotic acid by the oxygen from exocyclic C=O. Semiempirical PM3 calculations for both compounds were also carried out.