Synthesis of tetrametallic thiolate-bridged Fe3Au clusters. Crystal structure of [Fe3(CO)9(µ3-SPri){µ-Au(PPh3)}]

Abstract

The reaction of the lithium salt of [Fe₃(CO)₉(µ₃-SR)]^– with [Au(PPh₃)Cl], in the presence of TIBF₄, gives high yields of the new tetrametallic clusters [Fe₃(CO)₉(µ-SR){µ₃-Au(PPh₃)}](R = Prⁱ1, Bu^t2, C₆H₁₁3 or Et 4). Clusters 3 and 4 were formed along with the dimetallic species [Fe₂(CO)₆(µ-CO)(µ-SR){µ-Au(PPh₃)}](R = C₆H₁₁5 or Et 6). The structure of 1 has been determined by X-ray diffraction methods. The metal core consists of an isosceles triangle of iron atoms, capped by a Sprⁱ ligand and the longest iron–iron bond is bridged by an Au(PPh₃) fragment. The fast atom bombardment mass spectra of the positive ions of 1–4 show a similar pattern to that reported for [Fe₃(CO)₉(µ₃-SR)(µ-H)] consisting of a primary fragmentation involving stepwise loss of carbonyl groups from the parent ion to give [Fe₃-(SR){Au(PPh₃)}]⁺, followed by elimination of an olefinic group to give [Fe₃(SH){Au(PPh₃)}]⁺ and finally loss of hydrogen to afford [Fe₃(S){Au(PPh₃)}]⁺.