Synthesis, structural characterization and cytotoxicity of bimetallic chlorogold(I) phosphine complexes employing functionalized phosphinoferrocene carboxamides

Gold(I) phosphine complexes of the general formula [AuCl(Ph2PfcCONHY-κP)], where Y is CH2CO2Me (7), CH2CONH2 (8), CH2CH2OH (9), CH(CH2OH)2 (10), C(CH2OH)3 (11), and CH2SO3(HNEt3) (12), and fc is ferrocene-1,1′-diyl, were prepared from [AuCl(tht)] (tht = tetrahydrothiophene) and the appropriate phosphinoferrocene carboxamides (1–6). The compounds were characterized by spectroscopic and analytical methods, and the molecular structures of 7 and 9 were determined by single-crystal X-ray crystallography. Complexes 7–12 exerted antiproliferative activity against the human ovarian cancer cells in vitro. The IC50 values ranged ca. 0.3–3.7 μM for the A2780 cell line, and 3.1–20 μM for the cisplatin resistant cell line A2780R, with complex 7 being the most cytotoxic against both cell types. IC50 values for the non-tumorigenic human embryonic kidney (HEK) cells, serving as a measure of a general toxicity, were found in roughly similar ranges, i.e. 0.9–6.8 μM.