Synthesis, Characterization and Chemosensitivity Studies of Half-Sandwich Ruthenium, Rhodium and Iridium Complexes Containing к¹ _(S) and к² _(N,S) Aroylthiourea Ligands

The reaction of [(p-cymene)RuCl₂]₂ and [Cp*MCl₂]₂ (M = Rh/Ir) metal precursors with aroylthiourea ligands (L1-L3) yielded a series of neutral mono-dentate complexes 1–9. The neutral mono-dentate coordination of aroylthiourea with metals via S atom was confirmed by single crystal X-ray diffraction study. Further reaction of mono-dentate complexes 1–9 with excess NaN₃ in polar solvent resulted in the formation of highly strained four member ring к² _(N,S) azido complexes 10–18. Further these complexes were treated with activated alkynes to isolate triazole complexes, but unfortunately the reaction was unsuccessful. All these complexes were fully characterized by various spectroscopic techniques. The molecular structures of the representative complexes have been determined by single crystal X-ray diffraction studies. The molecular structures of the complexes revealed typical piano stool geometry around the metal center. The chemosensitivity activities of the complexes 1–9 evaluated against the cancer cell line HCT-116 (human colorectal carcinoma) and ARPE-19 (human retinal epithelial cells) cell line. Of these, complex 3 was the most potent and whilst its potency was less than cisplatin, its selectivity for cancer as opposed to non-cancer cell lines in vitro was comparable to cisplatin.