Stability of Carbon-Nitrogen Cages in 3-Fold Symmetry.

Molecules consisting entirely of nitrogen have been studied extensively for their potential as high energy density materials (HEDM). One class of potential high-energy nitrogen molecules is the cage of three-coordinate nitrogen. Previous theoretical studies of cages Nx have shown that the most stable isomers are cylindrical molecules with 3-fold symmetry and triangular endcaps, but such molecules are not stable with respect to dissociation. In the current study, nitrogen cages are modified to include carbon atom substituents. Carbon atoms are studied for their potential to stabilize the nitrogen structures while maintaining significant levels of energy release from the molecules. Theoretical calculations are carried out on a sequence of high-energy cages with carbon and nitrogen. Density functional theory (B3LYP), perturbation theory (MP2 and MP4), and coupled-cluster theory (CCSD(T)) are used in conjunction with the correlation-consistent basis sets of Dunning. Stability trends as a function of molecule size are calculated and discussed.