Since FeCp2 consists of one Fe 2+ ion and two Cp -ligands, we also considered the decomposition from the monovalent charged state (Cp -) to both charged and neutral C2H2 and C3H3 • . These reactions are displayed in reactions 18-21. Note, even if C5H5 • is formed, the negative ion formation to C5H5 -has shown to occur with low electron energies of 2.0 eV when ionizing C5H6, making the reactions probable. 51