Tuning In Vitro Cytotoxicity in Diruthenium(I) bis-Cyclopentadienyl Complexes

A series of diruthenium(I) aminocarbyne complexes of general formula [Ru2Cp2(CO)(L)(μ-CO){μ-CNMe (Cy)}]+ (L = NH3, [2]+; Py, [3]+, PPh3, [4]+; DMSO, [5]+; thiourea, [6]+) and [Ru2Cp2(μ-H)(CO)2{μ-CNMe (Cy)}], 7, were prepared from the tricarbonyl precursor [Ru2Cp2(CO)2(μ-CO){μ-CNMe (Cy)}]+. The reactivity of the diruthenium(I) vinyliminium complex [Ru2Cp2(CO)(μ-CO){μ-η1:η3-C (Ph)CHCNMe (Cy)}]+, was also investigated, providing access to piano stool Ru (II) cyclopentadienyl complexes with a five-membered metallacyclic ligand containing sulfur. The new compounds were characterized by IR and multinuclear NMR spectroscopy and X-ray diffraction (in three cases). The solubility in water, lipophilicity, and the speciation of [2–6]CF3SO3 in water/DMSO and cell culture medium are regulated by different monodentate ligands. Subsequently, [1,3–6]+ were tested in vitro against human ovarian cancer cells (A2780 and A2780cis) and embryonic kidney cells (HEK293), demonstrating moderate to potent cytotoxicity.