The monosubstituted ferrocenyl-amide phosphine ligands PPh 2CH2CH2NHCOFc and (PPh2CH 2CH2)2NCOFc and the disubstituted ferrocenyl-amide diphosphine (PPh2CH2CH 2NHCO)2Fc have been synthesized and used to prepare the gold chloride derivatives [AuCl(PPh2CH2CH 2NHCOFc)], [Au2Cl2{(PPh2CH 2CH2)2NCOFc}], and [Au2Cl 2{(PPh2CH2CH2NHCO)2Fc}] or the silver species [Ag(OTf)(PPh2CH2CH 2NHCOFc)2] and [Ag(OTf)(PPh3)(PPh 2CH2CH2NHCOFc)]. In the gold complexes the chloro ligands can be easily substituted by several biologically relevant thiolates such as 2-mercaptonicotinic acid, 2-thiocytosine, 2-thiouracil, 2-mercaptopurine, and 2,3,4,6-tetra-6-acetyl-1-thiol-β-d-glucopyranosato, affording the gold phosphine thiolate derivatives. In addition, the gold phosphine thiolates of the closely related 1,1′-bis(diphenylphosphine) ferrocene ligand have been prepared in order to compare their biological activities. The antiproliferative activity of these compounds has been tested by the MTT viability assay in two murine cell lines, NIH-3T3 (mouse embryonic fibroblasts) and PC-12 (pheochromocytoma of the rat adrenal medulla), and two human cell lines, A-549 (adenocarcinomic human alveolar basal epithelial cells) and Hep-G2 (hepatocellular carcinoma). The amide-phosphine ligands are not active, whereas the chloro-gold derivatives have good antiproliferative activity in the murine cell lines and very low activity in the human cell lines. The silver complexes are less active than the gold derivatives. The gold thiolate complexes have moderate to very good cytotoxic activity for all of the ligands, showing excellent IC50 values for the thiolate complexes of the amide-phosphines PPh2CH2CH2NHCOFc and (PPh 2CH2CH2N)2COFc and dppf. © 2013 American Chemical Society.

We thank the Ministerio de Economía y Competitividad-FEDER (CTQ2010-20500-C02-01) and DGA-FSE (E77) for financial support.

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