Abstract: This paper describes the syntheses of three new eight- membered ring explosives containing N-NOand gem-nitro groups. Some of their properties such as the impact sensitivity and thermal stability and others have been investigated. The electronic structures have been calculated by quantum chemical CNDO/2 method. It is shown that if the N-NO₂ group in these molecules is substituted by N-NOgroup, then the impact sensitivity of these explosives will obviously become lower. The C-Nbond gem-dinitro group for each eight-membered ring explosives is probably the initiation bond of the thermal decomposition because the bond order of the C-Nbond in gem-dinitro group is the lowest, and the corresponding bond energy of ℃-Nbond is the lowest, the C-Nbond in gem-nitro group is comparatively weak.

Key words: explosive, impact sensitivity, thermal stability, CNDO/2 calculation