Effect of Hydrogen Bond Interaction on the Decomposition Temperature, Aromaticity, and Bond Order of Nonmetallic Pentazolate Salts

Nonmetallic pentazolate (cyclo-N5 –) salts are novel polynitrogen high-energy-density materials with great potential and application prospects. Hydrogen bond networks play a vital role in improving the thermal stability of these compounds. In order to further increase the decomposition temperature (T d) and attain a more thorough exploration of these compounds, we evaluated and visualized the energy of hydrogen bonds (E_HBs) and the effects of HBs on T d, aromaticity, and the Mayer bond order (MBO). The increase in the total E_HBs can increase the T d, such as with 3,6,7-triamino-7H-[1,2,4]­triazolo­[4,3-b]­[1,2,4]­triazol-2-ium and biguanidinium pentazolates. Moreover, an increase in the maximum E_HBs can reduce the aromaticity of the cyclo-N5 – anion and increase the difference between the maximum and minimum MBO, like 3,9-diamino-6,7-dihydro-5H-bis­([1,2,4]­triazolo)­[4,3-e:3′,4′-g]­[1,2,4,5]­tetrazepine-2,10- diium and O-(carboxymethyl)­hydroxylammonium pentazolates. In addition, increasing the number of donors of hydrogen bonds, especially the proportion of O–H bonds, can significantly increase the T d of pentazolate salts.