Ruthenium(II) acetylacetonato–sulfoxide complexes

The water-soluble RuII acetylacetonato–sulfoxide complexes, cis-Ru(acac)2(DMSO)2 (1) and Ru(acac)2(meso-BESE) (2), were synthesized (BESE=1,2-bis(ethylsulfinyl)ethane=EtS(O)(CH2)2S(O)Et). Both complexes were characterized by 1H and 13C{1H} NMR, UV–Vis, and IR spectroscopies, as well as MS, elemental analysis, solution conductivity, and cyclic voltammetry, while the molecular structure of 2 was determined also by X-ray crystallography. All sulfoxide ligands are S-bonded. The complexes were tested against human breast cancer cells (MDA-MB-435S) using an in vitro MTT assay, a colorimetric determination of cell viability; IC50 values of >2000 and 1500 ± 100 μM were determined for 1 and 2, respectively, while cisplatin exhibits an IC50 value of 30 ± 5 μM.