A theoretical prediction of the molecular and electronic structures, thermodynamic properties, and stability of 1,3-diazido-2-methyl-2-nitropropane (DAMNP)

1,3-Diazido-2-methyl-2-nitropropane (DAMNP) is a newly synthesized azido compound and may be a potential candidate of the plasticizer of propellants. For better understanding its properties, the molecular conformations, electronic structure, IR spectrum, thermodynamic properties, pyrolysis mechanism, and specific impulse (I (S)) were studied using the B3LYP/6-31++G** method of density functional theory (DFT). The electronic structure of DAMNP was analyzed by the natural atomic charges, bond orders, donor-acceptor interactions, and molecular electrostatic potential (MEP). Results show that the main contributions to the highest occupied molecular orbital and the lowest unoccupied molecular orbital are from -N-3 and -NO2, respectively. The most negative area on the MEP locates at the O atoms of -NO2, which agrees with the atomic charges distributions. The pyrolysis mechanism was investigated by considering three possible bond dissociations (C-N-3, C-NO2, and N-N-2). Results show that the pyrolysis of DAMNP starts from the rupture of N-N-2 finished cooperatively via the H-transfer process to eliminate N-2. The lowest energy needed for pyrolysis is 165.13 kJ mol(-1). To verify the reliability of the method, the organic azido compound CH3N3 was also considered. DAMNP has a slightly higher thermal stability than CH3N3. However, using DAMNP to replace the plasticizer nitroglycerin of the nitramine modified double-base propellant leads to a decrease in I (S). Therefore, whether DAMNP can be really used as a plasticizer or not is worth further considerations.