Kinetic and mechanistic study of atmospheric reaction of NH3 with OOH radical

The reaction of NH3 with hydroperoxyl radical 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 basis sets. One pre-reactive complex, C1 was formed between ammonia and hydroperoxyl radicals. From a variety of this complex, three types of products are obtained that one of them are found to be thermodynamically stable. In thermodynamic viewpoint, 2H2NO+ 1H2O adduct is spontaneous and exothermic with -36.60 and -35.63 kcal/mol in Gibbs free energy and enthalpy of reaction at the UB3LP level, respectively. In kinetic point of view, the mentioned products after passing one low level transition state is the most favor pathway of reaction. In this reaction, for 2H2NO+ 1H2O adduct is the main thermodynamically and kinetically product. So, the rate constant are calculated at the 200-2500 K temperature range in the reliable pathway in this reaction.