New Atom/Group Volume Additivity Method to Compensate for the Impact of Strong Hydrogen Bonding on Densities of Energetic Materials

The quantitative impact of strong hydrogen bonding on the densities of energetic materials is discussed. On the basis of our new volume parameters designated for neutral high-energy density materials, the volume of each NH 2 or NH group must be corrected by −8 Å 3 to compensate for strong bonding: i.e., (1) when both carbon atoms vicinal to an NH 2 or NH group have nitro groups or one C−NO 2 and one N−oxide; or (2) if the molecule has C 2 symmetry, e.g., at least two nitro and two NH 2 groups in the vicinal position, two NH 2 groups may be corrected by −8 Å 3 in total (exemplified by 1,1-diamino-2,2-dinitroethene (FOX-7), 2,4,6-triamino-3,5-dinitropyridine (Cambridge Crystallographic Data Centre (CCDC) Refcode: TIBMUM), 2,6-diamino-3,5-dinitropyrimidine (CCDC refcode: CIWMAW01, etc.); or (3) when some heterocycles (triazole, pyrazole, etc.) contain the fragment −NHNO 2 . For 261 explosives with an average density of 1.803 g·cm −3, the mean absolute deviation (MAD) for the proposed current method is 0.026 g·cm −3, and the mean relative absolute error is 1.5 %.