Pentazole kinetic stability

The effects of cyclic 6n electron conjugation have been found in the optimized geometries of pentazole 17 [102] and hexazine 18 [97], The N=N bond is longer than the isolated double bond in NH=NH. The N-N single bond in the tetrazadiene moiety is shorter than the single bond in NH NH. The bond lengths in 18 are nearly intermediate between those in NH NH and NH=NH. The aromatic character of pentazoles was supported by the effect of electron donating substituents on the thermodynamic and kinetic stabilization [103],... 

The kinetic stability of pentazole has been estimated by the activation energy of decomposition or retro-[3 -i- 2]-cycloaddition reaction of 19.8 kcal moL [107] and 19.5 kcal mol- [108] with a half-life of only 14 s at 298 K [108]. 

While triazole compounds are not often energetic enough and pentazole species are kinetically too labile, the tetrazole derivatives often combine the desired endo-thermicity with kinetic stability (Fig. 9.7). Aminotetrazole (AT) and diaminotetraz-... 

In order to stabilize nitrogen-rich molecules, n aromatic delocahzation may be used. In this context five-membered heterocycles with three N atoms - triazoles -, four N atoms - tetrazoles -, and five N atoms - pentazoles - play an important role (Fig. 7). While triazoles often do not possess enough intrinsic energy to be suitable candidates for high explosives, pentazole derivatives are usually either far too sensitive and unstable for any application or need to be kinetically stabilized by bulky groups, which reduce the nitrogen con-... 

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