Fig. 7: Theoretical calculation of reaction mechanism (ethyl pathway, in black) with comparison with methyl pathway (in blue).

DFT calculations were carried out at the M06-2X-D3/ma-def2-TZVPP//M06-2X-D3/def-TZVP level of theory with continuum solvent model for CH3CN. Free energies referring to the change of free energy in the corresponding reactions are given in kcal mol−1.