Synthesis, characterization, and structural study of iron–sulfur core {Cp2Fe2(μ-SEt)2} complexes

The known complexes [Cp2Fe2(μ-SEt)2(MeCN)2](PF6)2 (1) and Cp2Fe2(μ-SEt)2(CN)2 (2) are prepared to investigate their reactivity. The reaction of complex 2 with equimolar amounts of MeOTf yields a monomethylation product [Cp2Fe2(μ-SEt)2(CN)(CNMe)](OTf) (3). Dimethylation of complex 2 by 2 equiv. MeOTf gives a complex [Cp2Fe2(μ-SEt)2(CNMe)2](OTf)2 (4). Complex 1 containing two labile MeCN ligands reacts with several bidentate phosphine ligands, such as dppm, dppa, and dppf, to afford complexes [Cp2Fe2(μ-SEt)2(dppm)](PF6)2 (5), [Cp2Fe2(μ-SEt)2(dppa)](PF6)2 (6), and [Cp2Fe2(μ-SEt)2(dppf)](PF6)2 (7), respectively. The spectroscopic, electrochemical, and reactivity studies of iron–sulfur core complexes are performed. The structures of complexes 1–7 were confirmed by X-ray crystallography.