Comparative Theoretical Studies on Several Energetic Substituted Dioxin-imidazole Derivatives

Abstract

The molecular structures, infrared spectra, heats of formation (HOFs), detonation properties, chemical and thermal stabilities of several tetrahydro-[1,4]dioxino[2,3-d:5,6-d′] diimidazole derivatives with different substituents were studied using DFT-B3LYP method. The properties of the compounds with different groups such as -NO2, -NH2, -N3, and -ONO2 were further compared. The -NO2 and -ONO2 groups are effective substituents for increasing the densities of the compounds, while the substitution of -N3 group can produce the largest HOF. The compound with -NO2 group has the same detonation properties as 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane, while the compound with -ONO2 group has lower detonation properties than those of hexahydro-1,3,5-trinitro-1,3,5-triazine. The nature bond orbital analysis reveals that the relatively weak bonds in the molecules are the bonds between substituent groups and the molecular skeletons as well as C–O bonds in the dioxin rings. The electron withdrawing groups (-NO2, -N3, and -ONO2) have inductive effects on the linkages between the groups and molecular skeletons. In addition, researches show that the electronegativities of the groups are related with the stabilities of the compounds. Considering detonation performance and thermal stability, the 1,5-dinitro-2,6-bis(trinitromethyl)-3a,4a,7a,8a-tetrahydro-[1,4]dioxino-[2,3-d:5,6-d′] diimidazole satisfies the requirements of high energy density materials.