Cytotoxic Half-Sandwich Rh(III) and Ir(III) beta-Diketonates

A series of half-sandwich pentamethylcyclopentadienyl rhodium(III) and iridium(III) complexes [CpM(DBM/ HDB/AVB)Cl] and [CpM(DBM/HDB/AVB)(PTA)]-[SO3CF3], where Cp* = pentamethylcyclopentadienyl, the proligands DBMH = dibenzoylmethane, HDBH = o-hydroxydi-benzoylmethane, AVBH = avobenzone, and PTA = 1,3,5-triaza-7-phosphaadamantane, is reported. All the complexes were characterized by IR, H-1 and C-13 NMR spectroscopy, electrospray ionization mass spectrometry, elemental analysis, and DFT calculations. Five of the complexes have also been characterized in the solid-state by X-ray crystallography. The cytotoxicity of the complexes has been evaluated against human ovarian A2780 and A2780cisR cell lines and, with the only exception of complexes 1 and 2 that display a negligible cytotoxicity, exhibit moderate cytotoxicity toward both cancer cell lines. However, the complexes do not show cancer cell selectivity with respect to human embryonic kidney HEK293 cells.