B3LYP calculations of the potential energy surfaces of the thermal dissociations and the triplet ground state of pyrolysis products [formula omitted] for halogen azides XN 3 (X: F, Cl, Br, I)

Abstract

Mechanisms of XN 3 (X: F, Cl, Br, I) dissociations are proposed based on B3LYP calculated potential energy surfaces. The energy gaps between the ground-state reactants XN 3( x ̃ 1 A ′) and the intersystem crossing (ISC) points are only a little lower than respective potential energy barriers of the spin-allowed reactions, XN 3( x ̃ 1 A ′)→ XN(a 1 Δ)+ N 2( x ̃ 1 Σ g +) . The ISC point, therefore, is considered as a ‘transition state’ of the spin-forbidden reactions, XN 3( x ̃ 1 A ′)→ XN( x ̃ 3 Σ −)+ N 2( x ̃ 1 Σ g +) . The methods of IRC and topological analysis of electron density are used to predict the thermal dissociation pathway of the reactions studied.