Anticancer Activity of Half‐Sandwich RhIII and IrIII Metalla‐Prisms Containing Lipophilic Side Chains

Two hexacationic pentamethylcyclopentadienyl rhodium(III) and iridium(III) metalla-prisms, [(η5-C5Me5)6M6(μ3-tpt-κN)2(μ4-C6HRO4-κO)3]6+ (tpt=2,4,6-tri-(pyridin-4-yl)-1,3,5-triazine; R=(CH2)10CH3; M=Rh, [3]6+; M=Ir, [4]6+) isolated as their triflate salts, have been synthesised from the dinuclear complexes (η5-C5Me5)2M2(μ4-C6HRO4-κO)Cl2 (M=Rh, 1; M=Ir, 2) and AgCF3SO3. The antiproliferative activity of the neutral and cationic complexes has been evaluated in vitro in human cancer cell lines. The positively charged metalla-prisms appear to target mitochondria, which ultimately induce apoptosis in cancer cells. All biological studies suggest that the rhodium derivative [3][CF3SO3]6 possesses excellent activities, not only in vitro but also in vivo in tumour-induced C57L6/J mice.