Synthesis and antiproliferative activity of ionic platinum(II) triphenylphosphino complexes

Ionic platinum(II) complexes [PtCl(PPh3)(L∧L)][BF4] {L∧L = 2,2′-bipyridyl (1) 1,10-phenanthroline (2)} and [PtCl(PPh3)(L)2][BF4] {L = pyridine (3), dimethyl sulfoxide (4)} were synthesized by dehalogenation of cis-[PtCl2(PPh3)(NCMe)], followed by reaction with the suitable ligand. Chelating nitrogen ligands L∧L afforded single products, which were structurally characterized. In the other cases mixtures of geometric (L = pyridine) and/or coordination (L = dimethyl sulfoxide) isomers were observed in solution. In these cases the structures of the less soluble isomers were obtained via single crystal X-ray diffraction. All the complexes were tested in vitro for their antiproliferative activity on three human tumor cell lines: MSTO-211H, HeLa and HepG2.