Synthesis and characterization of new trimetallic complexes with {Pt2Au(μ-S)2}n+ (n = 2, 3) cores containing C, N and N, N donor ligands

Reactions of the dinuclear platinum(II) sulfide complex [Pt2(μ-S)2(PPh3)4] with a range of gold(III) dichloride complexes [AuLCl2] containing C, N- or N, N-cycloaurated ligands L gives a new series of dicationic adducts [Pt2(μ-S)2(PPh3)4AuL]2+, isolated as their PF6− salts. The complexes investigated are [Au{C6–H4(CH2NMe2)-2}Cl2], [Au{C6H3(CH2NMe2)-2-(OMe)-5}Cl2], [Au{NC5H4(CH2C6H4)-2}Cl2], [Au{NC5H4(COC6H4)-2}Cl2] and [Au{NC5H4(CONH)-2}Cl2]. An X-ray structure determination on the picolinamide-derived complex [Pt2(μ-S)2(PPh3)4Au{NC5H4(CONH)-2}](PF6)2 was not of sufficiently high quality for detailed discussion, but confirmed the atom connectivity. Reactions of [Pt2(μ-S)2(PPh3)4] with [AuCl2(bipy)]PF6 (L = bipy = 2,2’-bipyridine) and [AuCl2(phen)]Cl (L = phen = 1,10-phenanthroline) gives the corresponding tricationic adducts [Pt2(μ-S)2(PPh3)4AuL]3+, also isolated as their PF6− salts. The complexes are characterised by NMR spectroscopy, electrospray mass spectrometry and microelemental analyses. Biological assay data of a selection of these new complexes towards the P388 murine leukemia cell line, as well as a range of antimicrobial tests, reveals overall low activity compared to other cycloaurated gold(III) complexes.