Theoretical study of substituent effects on the barrier energy of CH2NH + NO reaction in gas phase

The reaction of methanimine with NO on the doublet potential energy surface was carried out using the UMP2,UB3LYP and CCSD(T)//B3LYP theoretical approaches in connection with the 6-311++G (d, p) and some other basissets. Two pre-reactive complex, C1 and C2 was formed between CH2NH and nitric oxide. From a variety of thiscomplex, two types of products are obtained that one of them are found to be thermodynamically stable. Inthermodynamic viewpoint, CH3+N2O adduct is spontaneous and exothermic with -14.30 and -13.63 kcal/mol in Gibbsfree energy and enthalpy of reaction at the UB3LP level, respectively. In kinetic point of view, the mentioned productsafter passing one transition state is the most favor pathway of reaction. In this reaction, for HCN+ HNOH adduct is themain kinetically product. So, we have studied the substituent effects on the barrier energy in this path. The obtainedsubstituent effects analysis showed that the barrier energy is reduced when one of the hydrogen atom in –CH2 issubstituent via activating group such as –NH2.

Keywords:

Mechanism , methanimine , Potential energy surface , substituent , activating group