For better understanding the low temperature reaction pathway, the variations of reaction energetics as a function of temperature are explored and then analyzed by applying the energetic span model, in which the turnover frequency (TOF) determining transition state (TDTS) and TOF determining intermediate state (TDI) that maximize the energy span determine the rates and kinetics of the catalytic cycle . The energetic span approximation of the exothermal catalytic cycle to calculate turn over frequency ( 𝑇𝑂𝐹 ) from the energetic span (δE) of the free energy path: