Synthesis of a heterodinuclear ruthenium(II)-platinum(II) complex linked by l-cysteine methyl ester

A potential anticancer heterodinuclear ruthenium(II)-platinum(II) complex, [ruthenium(II)(4,4′-dimethyl-2,2′-bipyridine)2(5-(l-cysteine-methyl ester)-1,10-phenanthroline)-trans-chlorodiammineplatinum(II)] chloride, [Ru(Me2bipy)2(5-(l-cysteine-Me)-phen)-trans-Pt(NH3)2Cl]Cl3, was synthesised. l-Cysteine methyl ester was used to link the two metal centres, as more conventional straight chain diaminoalkanes and 2-mercaptoethylamine failed to couple to the phenanthroline ligand. From the precursor mononuclear ruthenium(II) complexes, which were separated into their -- and Λ-isomers by column chromatography, the dinuclear complex was synthesised and characterised by 1H and 13C NMR, UV-Vis, circular dichroism, fluorescence and electrospray ionisation mass spectrometry.