Cationic triruthenium(III) oxo complexes of the type [Ru3O(OAc)6L3]+ containing imidazole, pyrazole, thiazole and oxazole ligands: Synthesis, molecular structure, and cytotoxicity

• New cationic triruthenium complexes of the type [Ru3O(OAc)6L3]+ were synthesized.
• They contain N-heterocyclic ligands L such as imidazole, pyrazole, oxazole or thiazole.
• The molecular structure of the oxazole derivative was solved by X-ray crystallography.
• The benzothiazole derivative is weakly cytotoxic towards lung cancer cells.

The cationic complexes [Ru3O(OAc)6L3]+ [1: L = imidazole (imz), 2: L = pyrazole (pyz), 3: L = thiazole (taz), 4: L = oxazole (oxz), 5: L = benzimidazole (biz), 6: L = benzopyrazole (bpz), 7: L = benzothiazole (btz) and 8: L = benzoxazole (boz)] were synthesized by reaction of the precursor [Ru3O(OAc)6(MeOH)3]+ with the corresponding heterocycle and isolated as the triflate salts. In all complexes, the heterocycle is coordinated to ruthenium by the π-bonded nitrogen atom. The single-crystal X-ray structure analysis of [4][CF3SO3] shows the typical triruthenium μ3-oxo core, in which the three ruthenium atoms are pairwise bridged by two acetato ligands and N-coordinated by an oxazole ligand. The in vitro anticancer activity of 1–7 was studied with human lung cancer cells A549, the only active complex being the benzothiazole derivative 7 (IC50 = 49 μM).

New [Ru3O(OAc)6L3]+ cations containing N-coordinated heterocycles have been synthesized and characterized as the triflate salts, one of which (L = oxz) by single-crystal X-ray structure analysis. The benzothiazole derivative [Ru3O(OAc)6(btz)3]+ was found to show in vitro anticancer activity towards the human lung cancer cell line A549 similar to cisplatin.Figure optionsDownload as PowerPoint slide