Reactions of Fe+n clusters (n = 2–11) with C6H6 and C6D6. Ligand isomerization in the benzene precursor ion Fe4(C2H2)+3

Even though Fe+4 clusters in the gas phase have been demonstrated to be able to induce the cylotrimerization of added C2H2 ligands to benzene, the precursor ion Fe4(C2H2)+3 has not yet been structurally characterized. To improve our understanding of this type of ion, we compare the products obtained by the direct reaction of benzene with bare Fe+n clusters (n = 2–11) to those obtained by dehydrogenative addition of ethane. Additional mass spectrometric studies such as collision-induced dissociation (CID) and thermoneutral ligand exchange with C6D6 suggest that the reaction of C2H4 with Fe+4 produces at least two types of structural isomers, with a performed benzene molecule existing only in one of them (Fe4C6H+6).