Functionalization of the sumanene by nitrous oxide: A mechanistic study

Abstract

The mechanistic study of the cycloaddition reaction of nitrous oxide onto sumanene nanostructure carried out systematically using quantum chemistry methods. The 1,3-dipolar cycloaddition reaction of nitrous oxide with different kinds of C–C bond of sumanene in thirteen 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. Thirty-three transition states were identified for all pathways and confirmed by intrinsic reaction coordinate (IRC) calculations. The rate constants for all paths were calculated by using canonical transition state theory (CTST). Results showed that N2O addition to flank position is more favorable than other positions of sumanene, energetically. The major products are sumanene with an epoxide group in flank, spoke and hub6 positions; also products with an enol or oxepin group in rim and hub5 positions, respectively. Also, for all five positions, in the first step, C21H12N2O with a pentagon heterocycle contain O–N–N will be formed. In subsequent steps, either N2 extrusion or rearrangement can be done. Products related to outer positions of sumanene are more stable than corresponding products related to middle positions of sumanene (hub and spoke).