Ab initio calculations suggest that structures S(N-4) (m = 1-3) correspond to local energy minima on the relevant potential energy surfaces. S(N-4)(3) is 5.8 kcal/mol lower in energy than the transition structure of dissociation, and sulfur atom prefers an sp(3)d(2) hybridization. S(N-4)(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. (C) 2004 Published by Elsevier B.V.