Azolylpentazoles as high-energy materials: a computational study.
The structures of highly energetic substituted pentazole compounds and their decomposition to give dinitrogen and the corresponding azide were investigated by ab initio quantum chemical methods. The substituents include azolyl groups (five-membered aromatic rings with different numbers of nitrogen atoms), CH(3), CN, and F. The decomposition pathway was followed for several substituted azolyl- and phenylpentazoles and compared to the known experimental and theoretical results. The NMR parameters of most of the as-yet unknown pentazole compounds were predicted. The activation energy for the decomposition increases, while the decomposition energy of the substituted pentazole decreases with greater electron-donating character of the substituent of the pentazole. Thus, anionic pentazoles are more stable than neutral pentazoles. Methylpentazole is predicted to be among the most stable pentazoles, even though it does not contain an aromatic system.