Spectroscopic, DFT, magnetic and biological activity evaluation of Pd(II), Pt(II) and Ru(III) complexes of Nitazoxanide

[M(NTZ)Cl₂] (M = Pd(II) (1), Pt(II) (2) and NTZ = Nitazoxanide) and [Ru(NTZ)Cl₃(OH₂)] (3) complexes have been synthesized and characterized by elemental analysis, thermogravimetric analysis, IR, 1H NMR, conductance and magnetic measurements. NTZ is coordinated to the metal ions as a bidentate ligand via the N-atom of the thiazole ring and amide C[dbnd]O. The susceptibility of Staphylococcus aureus and Escherichia coli towards NTZ and its complexes has been evaluated. The calculated electronic structures and the related electronic transitions have been obtained at TD-DFT/B3LYP/LANL2DZ level of theory. Upon the chelation, the value of the natural charge of Ru(III) ion (+0.182e) was found to be lower than those of Pd(II) and Pt(II) ions (∼+0.398e) in their complexes, which reflects the higher complexation ability of NTZ towards the high oxidation state and low-d-orbital population metal ion. Complex 3 is existing in a low-spin octahedral arrangement. The DC magnetic measurements in terms of Weiss constant revealed the presence of the intermolecular interactions among the spin carriers. The low stability of 1–3 in DMSO and the rate of the releasing of NTZ was the factor which reproduces the order of the toxicity (NTZ > 2 > 3 > 1) against the tested microbes.