Ti(N5)4 as a Potential Nitrogen-Rich Stable High-Energy Density Material.

We have studied molecular structures and kinetic stabilities of M(N5)3 (M = Sc, Y) and M(N5)4 (M = Ti, Zr, Hf) complexes theoretically. All of these compounds are found to be stable with more than a 13 kcal/mol of kinetic barrier. In particular, Ti(N5)4 showed the largest dissociation energy of 173.0 kcal/mol and thermodynamic stability. This complex had a high nitrogen content (85% by weight), and a significantly high nitrogen to metal ratio (20:1) among the neutral M(N5)n species studied here and in the literature. Ti(N5)4 is thus forecasted to be a good candidate for a nitrogen-rich high-energy density material (HEDM). We reveal in further detail using ab initio molecular dynamics simulations that the dissociation pathways of M(N5)n involve the rearrangements of the bonding configurations before dissociation.