Quantum mechanical calculations were carried out using Gaussian 16 . Geometry optimizations and frequency calculations were obtained with the G4 methodology which has proven to provide low errors in the calculation of formation enthalpies of both closed-shell and open-shell species . Intrinsic reaction coordinate (IRC) calculations were carried out on the key optimized transition state structures to ensure that they are connected to the correct minima. Free energies at 1500 K and 1 atm were obtained using the Goodvibes software .