Synthesis and Characterization of Novel Iron(II) Complexes with Tridentate Semicarbazone and Thiosemicarbazone Ligands as Potential Redox-Active Antitumor Agents

This work reports the synthesis and characterization of four novel iron(II) complexes bearing tridentate semicarbazone and thiosemicarbazone ligands coordinating the metal through O,N,O or O,N,S donor sets. The complexes of general formula [Fe(L)_²]²⁺ were obtained from FeCl₂ . 6H₂O and the ligand (1:2) in acetonitrile, under argon at room temperature for 2 hours. UV-Vis showed characteristic metal-to-ligand charge-transfer transitions, along with n→π* trasitions in the complexes containing sulfur. Ciclic voltammetry revelead a quasi-reversible Fe(II)/Fe(III) couple for all complexes, within the range accessible to cellular oxidants and reductants, supporting their evaluation as candidate antitumor iron chelators.