Quantum-chemical study of the structure and thermochemical properties of nitropiperazines and nitrosopiperazines

Abstract

We have used MNDO and PM3 approximations and the density functional method (6–31G*) for a quantum chemical study of the structure and some physicochemical properties of N-nitro and N-nitroso derivatives of piperazine, furazano[3,4-b]piperazine, and bisfurazano[3,4-b;3′,4′-e]piperazine. We have analyzed the structural, electronic, and thermochemical characteristics and the enthalpies of formation for the compounds in the gas phase and in the solid phase. We have found a correlation between the strength of the N-N bond and the N-N bond length, the pyramidality of the nitrogen atom of the piperazine ring, and the size of the energy gap between the frontier orbitals. Based on calculations by the density functional method, we have carried out a comparative analysis of the thermochemical stability of the compounds in homolytic reactions.