Synthesis and anticancer activity evaluation of η5-C5(CH3)4R ruthenium complexes bearing chelating diphosphine ligands

The complexes [RuCp*(PP)Cl] (Cp* = C5Me5; [1], PP = dppm; [4], PP = Xantphos), [RuCp#(PP)Cl] (Cp# = C5Me4(CH2)5OH; [2], PP = dppm; [5], PP = Xantphos) and [RuCp*(dppm)(CH3CN)][SbF6] [3] were syn- thesized and evaluated in vitro as anticancer agents. Compounds 1–3 gave nanomolar IC50 values against normoxic A2780 and HT-29 cell lines, and were also tested against hypoxic HT-29 cells, maintaining their high activity. Complex 3 yielded an IC50 value of 0.55 ± 0.03 μM under a 0.1% O2 concentration.