Mononuclear half-sandwich cyclic-π-perimeter platinum group metal complexes having bithiazole ligands: Synthesis, molecular and anti-cancer studies

Mononuclear cationic half-sandwich arene Ru(II) and Cp ^*Rh(III)/Cp^*Ir(III) compounds with the general formula [(η⁶-arene)Ru(L)Cl]⁺ and [Cp ^*M(L)Cl]⁺ have been isolated by the reaction of bithiazole ligands {2,2′-dimethyl-4,4′-bithiazole (dm4bt), 2,2′-diamino-4,4′-bithiazole (da4bt), and 2,2′-diphenyl-4, 4′-bithiazole (dp4bt)} with the precursor compounds [(η⁶- arene)Ru(μ-Cl)Cl]₂ (arene = C₆H₆, p- ⁱPrC₆H₄Me or C₆Me₆) and [Cp^*M(μ-Cl)Cl]₂ (M = Rh, Ir). These compounds were isolated as SbF₆ salts and fully characterized by spectral studies. Some representative compounds were confirmed by single crystal X-ray crystallographic studies. Chemo-sensitivity activities of compounds 1, 5, 11, 12, 14 and 15 were evaluated against two human breast carcinoma cell lines (MDA-MB-231 and T47D). There is a clear SAR seen, where the iridium-based complexes with the dp4bt ligand are much more potent than the ruthenium and rhodium complexes.