Calculated Structures and Electrostatic Potentials of Some 1,4-Dioxazines and 1,4-Dioxadiazines

摘要

An ab initio SCF computational study has been performed on the structural features, relative stabilities and electrostatic potentials of 1,4,2-dioxazine and its 3-nitro derivative and the three isomeric 1,4-dioxadiazines and their dinitro derivatives. Within the two sets of isomeric diazines, those with ring nitrogens adjacent to each other are by far the least stable. Due to the presence of so many electronegative atoms competing for the polarizable electronic charge, the negative electrostatic potentials associated with the ring heteroatoms are weaker than is generally observed for nitrogen and oxygen lone pairs, and no negative potentials are found above the double bonds. The basicities of the ring nitrogens and the reactivities of the double bonds toward electrophiles are therefore expected to be relatively low. The nitro derivatives show buildups of positive potential above the rings and the C-NO2 bond regions, which are expected to facilitate the approach of nucleophiles. Keywords: Structures; Dioxazines; Dixoadiazines; Electrostatic potential; Nitrodioxdiozines; nitrodioxadiazines, Reprints. (mjm)