Theoretical studies on the stability of salts formed by 3-substituted 6-nitraminotetrazines with different cations

A series of energetic salts based on the cations NH4 (+), NH3OH(+), N2H5 (+) and C(NH2)3 (+) and the anions of 6-nitraminotetrazine and its 3-substituted derivatives of -NH2, -N3, -ONO2, -NF2 or -NO2 was studied using dispersion-corrected density functional theory (DFT-D). In comparison with salts of unsubstituted 6-nitraminotetrazine, -NH2 substitution strengthens the hydrogen bonding interaction and other intramolecular interactions (such as charge transfer, binding energy, second-order perturbation energy and dispersion energy), -N3 has tiny effects on these interactions, and other groups weaken these interactions, with weakening decreasing in the order -NO2 > -NF2 > -ONO2. The ability of the cations to produce strong intramolecular interactions decreases in the order NH3OH(+) > N2H5 (+) > NH4 (+) > C(NH2)3 (+), which is contrary to the order of the basicity of bases. Stronger intramolecular interactions lead to more stable salts. All substituent groups improved the chemical stability except -ONO2, while cations had no effect on chemical stability. All substituent groups were helpful in improving aromaticity, in the sequence -ONO2 > -NF2 > -NO2 > -N3 > -NH2.