Synthesis of the ferrocene derivative FcCHN(CH2)2SH [Fc = (η5-C5H5)Fe(η5-C5H4)]:: Reactivity toward (phosphine)gold(I) cations

The condensation reaction of ferrocenecarbaldehyde with beta-mercaptoethylamine gives FcCHN(CH2)(2)SH [Fc = (eta(5)-C5H5))Fe(eta(5)-C5H4)], which is easily oxidized to the disulfide derivative FcCHN(CH2)(2)S-2(CH2)(2)NCHFc. Treatment of FcCHN(CH2)(2)SH with [AuCl(PPh3)] in the presence of Na2CO3 affords the thiolate gold(I) complex [FcCHN(CH2)(2)S(AuPPh3)]. Further reaction of the latter with various molar ratios of [Au(TfO)PPh3] (TfO = trifluoromethanesulfonate) leads to di-, tri-, and tetranuclear gold species in which the metallic centers are bonded to the sulfur and nitrogen ligands. The reaction of FcCHN(CH2)(2)SH with [Au-2(TfO)(2)(mu-dppf)] in a 1:1 or 1:2 molar ratio has also been carried out to give [FcCHN(CH2)(2)S{Au-2(mu-dppf)}]TfO or [FcCHN(CH2)(2)S{Au-2(mu dppf)}(2)](TfO)(3). The crystal structure of [FcCHN(AuPPh3) (CH2)(2)S(AuPPh3)(2)] (TfO)(2) reveals short gold-gold interactions.