Synthesis, X-ray diffraction structure, spectroscopic properties and antiproliferative activity of a novel ruthenium complex with constitutional similarity to cisplatin

The light-protected reaction of [(eta(6)-p-cymene)Ru(II)Cl(2)](2) with 1-(2-hydroxyethyl)piperazine in dry methanol, followed by addition of excess NH(4)PF(6), afforded the complex [(eta(6)-p-cymene)Ru(II)(NH(3))(2)Cl](PF(6)) () in 47% yield. Attempts to use the same protocol for the synthesis of [(eta(6)-p-cymene)Os(II)(NH(3))(2)Cl](PF(6)) led to the isolation of the binuclear triply methoxido-bridged arene-osmium compound [{(eta(6)-p-cymene)Os}(2)(mu-OCH(3))(3)](PF(6)) (). Both compounds were characterised by X-ray crystallography and (1)H NMR spectroscopy, and the ruthenium complex also by spectroscopic techniques (IR and UV-vis spectroscopies). The antiproliferative activity of complex in vitro was studied in A549 (non-small cell lung carcinoma), CH1 (ovarian carcinoma), and SW480 (colon carcinoma) cells and compared to that of [(eta(6)-p-cymene)Ru(II)(en)Cl](PF(6)) (). In contrast to the latter compound, is only modestly cytotoxic in all three cell lines (IC(50): 293-542 muM), probably due to the instability of the diammine ruthenium complex in aqueous solution.