ab initio Calculations and Mechanism of 1,3-Dipolar Additions on ethylene

Abstract

ab initio calculations for the dipolar addition of ethylene with CNO, N₂O, ONO and O₃ have been carried out using hybrid density functional B3LYP and moller plesset energy correlation MP2 with aug-cc- PVDZ basis sets using Gaussian 03 suite of programmes. A cyclic Diels Alder type mechanism is suggested for N₂O and CNO and a fragmented one for ONO and O₃ using geometry optimization and harmonic vibrational frequencies. The shift in mechanism is due to difference in the ambivalent character of dienophiles.