Platinum(II) and palladium(II) complexes mediated by β-hydroxy-dithioesters ferrocenyl derivatives: synthesis, characterization and antiproliferative activity

Ferrocene and its derivatives compounds have shown a significant role in medicinal organometallic chemistry as an antiparasitic or antibacterial. Therefore, we herein report on the utilization of dithioesters ferrocenyl derivatives as proligands for the synthesis of heteroleptic platinum(II) and homoleptic palladium(II) complexes bearing a conserved O,S binding moiety. The resulting complexes [Pt(L1)(DMSO)Cl] (1), [Pt(L2)(DMSO)Cl] (2), [Pt(L3)(DMSO)Cl] (3), [Pd(L1)(2)] (4), [Pd(L2)(2)] (5), and [Pd(L3)(2)] (6), in which HL1 = methyl 3-hydroxy-3-ferroceneprop-2-enedithioate, HL2 = ethyl 3-hydroxy-3-ferroceneprop-2-enedithioate and HL3 = propyl 3-hydroxy-3-ferroceneprop-2-enedithioate, were fully characterized employing a variety of analytical techniques (NMR spectroscopy, elemental analysis, and mass spectrometry and X-ray structure determination of complexes 2 and 6). Cytotoxicity assays of the synthesized ligands as well as the Pt/Pd metal complexes showed low toxicity towards ovarian cancer cells, but the compounds are not affected by cisplatin resistance mechanisms. Pt(II) complexes exhibited the highest activity, and the alkyl substituent strongly influenced the activity of these complexes and the free ligands. The cytotoxic activity increases with the length of the alkyl chain with 3 exhibiting a mean IC50 of 56 mu M.

Automated summary

Ferrocene and its derivatives compounds are important in medicinal organometallic chemistry as antiparasitic or antibacterial agents. This study focuses on the use of dithioester ferrocenyl derivatives to synthesize platinum(II) and palladium(II) complexes with a conserved O,S binding moiety. The synthesized complexes were characterized using various analytical techniques and showed low toxicity towards ovarian cancer cells, unaffected by cisplatin resistance mechanisms. The Pt(II) complexes exhibited the highest activity, with cytotoxic activity increasing with the length of the alkyl chain.