A series of ruthenium-benzene complexes with β-diketiminate ligands modified with electron-withdrawing groups were prepd. 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-contg. drugs. A related complex with a η6-C6H5CF3 ligand was prepd. and found to undergo a nucleophilic addn. reaction at the coordinated arene ring to afford a substituted η5-cyclohexadienyl deriv.