Abstract
[MCl(H2L)(OH2)]·1.5H2O (M = Pd(II) (1) and Pt(II) (2)) and [Ru(H2L)2(OH2)2]·3H2O (3) (H3L: N‐phenyl, N`‐(3‐triazolyl)thiourea) were synthesized, characterized and tested for their antibacterial activities against Staphylococcus aureus and Escherichia coli bacteria. The thiourea derivative is coordinated to Mn+ ions as a mono‐negatively N,S‐bidentate ligand via the enolization of C = S group and triazole N center. The density functional theory calculations reveal that presence of a water molecule in a trans position to triazole ring increased the stability of d8 metal ions complexes via the formation of strong Cl…NH intramolecular H‐bond. The cis‐Ru(II)‐isomer with two isoenergetically H2L− molecules are more stable than the trans‐analog. Coordination of H3L to Ru(II) ion did not alter the toxicity of the free ligand, while the interaction with the d8 metal ions gave rise to inactive compounds.
DFT calculations reveal that presence of H2O, in the coordination spheres of Pd(II) and Pt(II) complexes of the title ligand, in a trans‐position to the triazole ligand with increase the stability via the formation of strong Cl…NH hydrogen bond. Alternatively, the cis‐isomer of Ru(II) complex is more stable than the trans‐analog. The ligand interacts with the metal ions via the enolization of NH‐C = S‐ group and triazole nitrogen atom as evidenced by the analytical and spectral tools.