Rational Design of Highly Cytotoxic η⁶-Arene β-Diketiminato−Ruthenium Complexes

A series of ruthenium−benzene complexes with β-diketiminate ligands modified with electron-withdrawing groups were prepared and characterized by NMR spectroscopy, mass spectrometry, and single-crystal X-ray diffraction. The complexes are stable in air and undergo controlled hydrolysis in water. The complexes were evaluated for anticancer activity in vitro, and two of them proved to be highly cytotoxic, comparable or even superior to cisplatin. This work shows the potential utility of the β-diketiminate ligand in the rational design of new anticancer metal-containing drugs. A related complex with a η 6 -C 6 H 5 CF 3 ligand was prepared and found to undergo a nucleophilic addition reaction at the coordinated arene ring to afford a substituted η 5 -cyclohexadienyl derivative.