Iridium-Stabilized pi-Selenocyclohexadienyls: Synthesis, Molecular Structure, and Cytotoxicity

A series of iridium-stabilized selenocyclohexadienyls of general formula [CpIr((5)-C6H5-nMenSe)][BF4] {Cp = (5)-C5Me5, n = 0, n = 1, and n = 3} is described, with the selenocyclohexadienyl unit being isolated for the first time by -coordination to a CpIr moiety. The solid-state structure of one of [CpIr((5)-C6H2Me3Se)][BF4] was determined by single-crystal X-ray diffraction analysis. These compounds are obtained in good yields as orange-red microcrystalline solids by halogen displacement from the related -bonded arene-chlorinated starting materials using Na2Se as the selenium source. Furthermore, these new compounds display relevant cytotoxic properties towards human ovarian cancer cells.