Stability of high-energy nitrogen-rich sulfides S(N4)m

Ab initio calculations suggest that structures S(N4)m (m=1–3) correspond to local energy minima on the relevant potential energy surfaces. S(N4)3 is 5.8 kcal/mol lower in energy than the transition structure of dissociation, and sulfur atom prefers an sp3d2 hybridization. S(N4)2 and SN4 are somewhat more stable kinetically, due to 17.3 and 13.5 kcal/mol barriers of dissociation. The low gas phase barriers of S(N4)m mean that these nitrogen-rich sulfides require external stabilization if they are to be used as high-energy density materials. The special role of the sulfur d-orbitals in the geometrical arrangements of these systems was also investigated.