Explosive molecular ionic crystals.
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(-), N(3)(-), NCO(-), or NCS(-) (an isoelectronic set of unsaturated linear triatomic anions). Another such family are the globular oxyanions X(-) = ClO(2)(-), ClO(3)(-), ClO(4)(-), NO(3)(-), and MnO(4)(-). Mishandling of NH(4)NO(3) or NH(4)ClO(4) 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 X(2)(-), exothermic reactions proceed with high yield.
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