The unusual reactions of indium(I) trifluoromethanesulfonate with some first row metallocenes and the structure of “indium(II) cyclopentadienide”

The soluble reagent indium(I) trifluoromethanesulfonate, InOTf, does not appear to react or interact with ferrocene (Cp2Fe, Cp = C5H5) whereas cobaltocene reacts with InOTf to produce [Cp2Co]+[OTf]− and indium metal. Unexpectedly, the reaction of InOTf with manganocene results in the formation of the unprecedented salt [In(μ2,η5-Cp)In]+[Cp3In(μ2,η1-Cp)InCp3]−: a form of “Cp2In” that is characterized by X-ray crystallography. Similarly, the reaction of InOTf with [Cp2Fe]+[PF6]− produces Cp2Fe and “In4OTf6” in addition to other products. The unusual structural features and the formation of the new indium-containing products are rationalized.