Transition metal complexes of 6-amino 2-thiouracil; crystal structure of bis(6-amino-2-thiouracilato)aquazinc(II) dihydrate

Complexes of 6-amino-2-thiouracil (H2ATU) with the metal ions Ni(II), Co(II), Zn(II), Cd(II), Cu(I), Ag(I), and Hg(II) have been isolated and characterized by means of elemental analysis, infrared, NMR, and visible spectroscopies, and magnetic measurements. The crystal structure of [Zn(HATU)2(H2O)] • 2H2O has been solved by X-ray diffraction showing that the metal atom is five-coordinated by a water molecule and two ligands that bind through the sulphur and N1 atoms, closing a four-member chelate ring. Diffuse reflectance spectra and magnetic measurements suggest that [Co(HATU)2(H2O)] • 2H2O has a similar structure to that of the zinc complex, and that the nickel complexes [Ni(HATU)2] and [Ni(HATU)2(H2O)2] have, respectively, a tetrahedral and a D4h-distorted octahedral environment.