Theoretical Investigation of Energetic Salts with Pentazolate Anion

Energetic salts based on pentazolate anion (cyclo-N₅^-) have attracted much attention due to their high nitrogen contents. However, it is an enormous challenge to efficiently screen out an appropriate cation that can match well with cyclo-N₅^-. The vertical electron affinity (VEA) of the cations and vertical ionization potential (VIP) of the anions for 135 energetic salts and some cyclo-N₅^- salts were calculated by the density functional theory (DFT). The magnitudes of VEA and VIP, and their matchability were analyzed. The results based on the calculations at the B3LYP/6-311++G(d,p) and B3LYP/aug-cc-pVTZ levels indicate that there is an excellent compatibility between cyclo-N₅^- and cation when the difference between the VEA of cation and the VIP of cyclo-N₅^- anion is -2.8 to -1.0 eV. The densities of the salts were predicted by the DFT method. Relationship between the calculated density and the experimental density was established as ρ_Expt = 1.111ρ_cal - 0.06067 with a correlation coefficient of 0.905. This regression equation could be in turn used to calibrate the calculated density of the cyclo-N₅^- energetic salts accurately. This work provides a favorable way to explore the energetic salts with excellent performance based on cyclo-N₅^-.