Structural Properties of High-Energy NC Molecules: Cyclic Hexamers of NCN.

Molecules with high nitrogen content are of interest for their potential as high-energy materials. However, many molecules with 100% nitrogen content are unstable and dissociate with low barriers, which limits practical applications. In the present study, cyclic hexamers of the basic unit NCN (70% nitrogen by mass) are studied to determine the structural features and bonding characteristics that lead to more stable molecules. Double- and triple-bonded NCN units are compared to determine which form of NCN contributes the greater stability. Theoretical calculations using density functional theory and couple-cluster theory are carried out on a series of NC molecules to determine trends in stability. Energetic and structural trends, as well as differences between DFT and coupled-cluster theory, are calculated and discussed.