Synthesis, Structure and Bactericide Activity of (Aminophosphane)gold(I) Thiolate Complexes

Abstract

AbstractReaction of the aminophosphane ligands 2‐(diphenylphosphanylamino)pyridine (Ph2PNHpy, 1) and 3‐(diphenylphosphanylamino)‐1,2,4‐triazole [Ph2PNH(Htrz), 2] with the gold(I) compound [AuCl(tht)] (tht = tetrahydrothiophene) gave the complexes [AuCl(Ph2PNHpy)] (3) and [AuCl{Ph2PNH(Htrz)}] (4), respectively. A series of new gold(I) thiolate derivatives were synthesized from the reactions of complex 3 or 4 with 1 equiv. of a deprotonated thiol ligand. Complexes [Au(SR)(PPh2NHpy)] (5–8) were prepared by reaction of complex 3 with the corresponding thiol HSR [HSR = 2‐mercaptopyridine (2‐HSpy), 2‐mercaptonicotinic acid (2‐H2‐mna), 2‐thiouracil (2‐HTU) or 2‐thiocytosine (2‐HTC)] in the presence of sodium carbonate or triethylamine. Complexes [Au(SR){PPh2NH(Htrz)}] (9–11) were prepared by the treatment of complex 4 with triethylamine and the respective thiol HSR [HSR = 2‐mercaptopyridine (2‐HSpy), 2‐thiocytosine (2‐HTC) or 6‐thioguanine (6‐HTG)]. The susceptibility of Enterococcus faecalis ATCC25923, Staphylococcus aureus ATCC29213 and Escherichia coli TG1 towards the synthesized gold(I) complexes was evaluated. Some of them exhibit powerful anti‐bacterial activity, being more efficient against Gram‐positive microorganisms. Complexes 7–9 and 11 present excellent activity against E. faecalis, whereas the highest sensitivity of S. aureus was against complexes 7 and 8. The structures of complexes 4, 5, 8 and 9 were determined by X‐ray structural analysis. None of the four compounds shows aurophilic interactions between the gold(I) centres in the crystals. The four complexes possess intermolecular hydrogen bonds that lead to supramolecular arrangements.