Explosive Molecular Ionic Crystals

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Science  07 Jul 1989:
Vol. 245, Issue 4913, pp. 37-42
DOI: 10.1126/science.245.4913.37


In ionic crystals of the form M+X-, certain covalently bonded anion groups X- are particularly associated with instability. The heavier metal cations M+ enhance this. Very sensitive explosives occur within the extended azide family, where X- = CNO-, N3-, NCO-, or NCS- (an isoelectronic set of unsaturated linear triatomic anions). Another such family are the globular oxyanions X- = ClO2-, ClO3-, ClO4-, NO3-, and MnO4-. Mishandling of NH4NO3 or NH4ClO4 has caused major disasters. An irreversible cyclic mechanism is proposed for such decomposition, involving mechanoelectronic band-gap excitation and coalescence of X with X-. From an intracrystalline ion-molecule collision complex, the singly charged dianion X2-, exothermic reactions proceed with high yield.