Eaton and colleagues were created octanitrocubane's nitro-less parent, cubane, in 1964. Cubane is very dense, 1.29 g cm-3, among the dozen or so most dense saturated hydrocarbons. This combined with its high heat of formation led scientists at the US Army Armament Research and Development Centre (ARDEC) to propose octanitrocubane (ONC) as a new explosive.
The aptly named cubane (C8H8) has a molecular framework of eight carbon atoms placed at the corners of a cube. With a C-C-C bond angle of 90° rather than the standard 109.5° for most hydrocarbons the strain energy stored in the chemical bonds is great: 150 kcal/mol. When the hydrogen atoms are replaced with eight energy-rich nitro groups the result is a powerful explosive.
The nitro groups provide oxygen for combustion of carbon and the nitrogen groups combine to release dinitrogen (N2), further increasing the volume of liberated gas.
The high density of ONC is also crucial to its strength as an explosive, because the pressure of the detonation increases tremendously with increasing density of the explosive of the explosive. The density of ONC is approximately 2 g cm-3, significantly higher than that of TNT (1.53 g cm-3) and octogen/ HMX (1.89 g cm-3).
Although not enough ONC has been produced to test its incredible blasting potential, all the evidence suggests that is more powerful than the best non-nuclear explosives.
Octanitrocubane Movie (University of Washington Department of Chemistry)