Metal complexes of antiuralethic drug: Synthesis, spectroscopic characterization and thermal study on allopurinol complexes

Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Hg(II) complexes of the allopurinol ligand, (H2L; Alp(C5H4N4O)), were synthesized and characterized by microanalyses, magnetic susceptibility, conductance, infrared, electronic spectral and thermogravimetric (TGA/DTG) measurements. The ligand can be coordinated as a bidentate feature via pyrazole and/or pyrimidine rings. Spectroscopic and magnetic data are consistent with configuration of square planar geometry for the Mn(II), Co(II), Zn(II), Cd(II) and Hg(II) complexes while the Ni(II) and Cu(II) complexes are octahedral. From the thermal degradation curves, the uncoordinated water molecules are removed in a first stage while the decomposition of ligand beside coordinated water molecules occur in the second and subsequence steps. The kinetic thermodynamic parameters such as: E∗, ΔH∗, ΔS∗ and ΔG∗ are estimated from the DTG curves using Coats and Redfern (CR) and Horowitz–Metzger equations.