COMPUTATIONAL STUDY OF THE GAS PHASE REACTION OF HNCO AND SUMANENE: A DFT STUDY

The mechanistic study of the cycloaddition reaction of HNCO onto sumanene nanostructure carried out systematically using quantum chemistry methods. The 1,3-dipolar cycloaddition reaction of HNCO with different kinds of C–C bond of sumanene in twenty pathways was investigated. Geometry of reactants, transition states, intermediates and products were optimized at B3LYP/6-311+G(d) level of theory. Vibrational frequencies and relative energies for all stationary points were determined. Eighty one transition states, thirteen product and sixty one intermediate were identified and the rate constants for all paths were calculated by using canonical transition state theory (CTST). In the first step, C22H13NO with a pentagon heterocycle contain HN–C–O forms for all positions. According to all calculated data and reported results, HNCO addition to rim position is the most diverse reaction with 61-transation sates, but HNCO addition to flank position is more favorable than other positions of sumanene, energetically.