Ruthenium(II/III)-based compounds with encouraging antiproliferative activity against non-small-cell lung cancer

Hereby we present the synthesis of several ruthenium(II) and ruthenium(III) dithiocarbamato complexes. Proceeding from the Na[trans-Ru(III)(dmso)(2)Cl(4)] (2) and cis-[Ru(II)(dmso)(4)Cl(2)] (3) precursors, the diamagnetic, mixed-ligand [Ru(II)L(2)(dmso)(2)] complexes 4 and 5, the paramagnetic, neutral [Ru(III)L(3)] monomers 6 and 7, the antiferromagnetically coupled ionic α-[Ru(III)(2)L(5)]Cl complexes 8 and 9 as well as the β-[Ru(III)(2)L(5)]Cl dinuclear species 10 and 11 (L = dimethyl- (DMDT) and pyrrolidinedithiocarbamate (PDT)) were obtained. All the compounds were fully characterised by elemental analysis as well as (1)H NMR and FTIR spectroscopy. Moreover, for the first time the crystal structures of the dinuclear β-[Ru(III)(2)(dmdt)(5)]BF(4)⋅CHCl(3)⋅CH(3)CN and of the novel [Ru(II)L(2)(dmso)(2)] complexes were also determined and discussed. For both the mono- and dinuclear Ru(II) and Ru(III) complexes the central metal atoms assume a distorted octahedral geometry. Furthermore, in vitro cytotoxicity of the complexes has been evaluated on non-small-cell lung cancer (NSCLC) NCI-H1975 cells. All the mono- and dinuclear Ru(III) dithiocarbamato compounds (i.e., complexes 6-10) show interesting cytotoxic activity, up to one order of magnitude higher with respect to cisplatin. Otherwise, no significant antiproliferative effect for either the precursors 2 and 3 or the Ru(II) complexes 4 and 5 has been observed.