The reaction enthalpy for reactions 12-15 was found to be 1.7 eV (168 kJ/mol), -0.9 eV (-92 kJ/mol), 4.6 eV (449 kJ/mol) and 0.1 eV (8 kJ/mol), respectively. The presented DFT reaction pathways (reactions 4-15) and their respective ∆ 𝑟 𝐸, ∆ 𝑟 𝐻 and ∆ 𝑟 𝐺 are summarized in Table in supplementary material. Additionally, reactions leading to the negative ion formation of Cp - has earlier been measured to have a cross section on the order of 10 21 cm 2 , making Cp -a likely product in the decomposition. We further investigated the decomposition of the Cp (C5H5) ligand to C2H2 and C3H3, which has been discussed earlier when modelling kinetics of thermal decomposition of Cp. Additionally, production of C2H2 and C3H3 • has also been discussed as products in several other decomposition studies, e.g., through hydrocarbon combustion. There are many isomers of C3H3 • and we considered the most stable isomers, i.e., the cyclic (cyclopropenyl radical) and linear (propargyl radical) isomers, according to reaction formulas 16 and 17. The decomposition of Cp leading to C2H2 and C3H3 • showed reaction enthalpies of 3.1 eV (reaction 16) and 4.6 eV (reaction 17), implying that the routes are thermodynamically possible. Although, to our knowledge, no cross sections have been found for reactions 16 and 17.