Chemistry of aliphatic unconjugated nitramines. Part 4.—Photophysical processes of secondary nitramines

Abstract

A zero-order Born-Oppenheimer approximation of the electronically excited states of secondary aliphatic unconjugated nitramines is given, and their subsequent photophysical processes, for irradiation with 254 nm light, are deduced therefrom. This data could not be obtained by experiment. We suggest that RDX and HMX form charge transfer (CT) complexes upon crystallization. These complexes appear unique in that their CT exciton band is of lower energy than the normal singlet exciton band of their molecular crystals. Static reactivity indices are used to predict the likely primary dissociative products obtainable from each excited state of secondary nitramines; theory predicts that the axial and equatorial nitramine groups of the polynitramines RDX, α- and β-HMX, may possess quite novel selective decomposition paths and hence give different primary dissociative products.