We also considered the possibility of electron attachment (EA) reactions, which is relevant for plasma CVD processes. We considered both a single and double EA of FeCp2, generating negative monovalent (FeCp2 -) and bivalent (FeCp2 2-) ions, according reactions 10 and 11. The small difference might be due to the use of different basis sets and we speculate that the positive value of the reaction enthalpy for FeCp2 -is due to the basis set size limitations (since the reaction is expected to be slightly exothermic). Nonetheless, the calculations point to the fact that these reactions are thermodynamically feasible pathways.