There is no significant change in the energy required for the formation of the pre-complex (6A CN ). However, an enthusiastic change in activation energy is observed. The required activation energy for the formation of the transition state (T S6 CN ) is only 11.6 kcal/mol which is lower by 9.2 kcal/mol compared to its nitrogen analog. Thus, PHC is highly reactive to nitrogen even under ambient conditions. Not only that, the diazo derivative of PHC (6B CN ) is thermodynamically stable too. The Gibbs' free energy change for this process is -10.1 kcal/mol. From this study, it may be concluded that a proper mutation at the heteroatom may reduce the activation energy of the reaction and at the same time, it may increase the stability of the product.