Theoretical studies have suggested that the stabilizing factors for large nitrogen cages tend to favor more five-membered rings, more three-membered rings and cylinder-shaped structure with large numbers of layers. Our further studies on the relative stability of all-nitrogen cages suggest that the stabilizing factors originate from the intramolecular interactions. The cylinder-shaped of N-84 (D-3d) has been studied in detail. To fully understand the bonding in this cage molecule, NBO and AIM analyses are performed. The results show that the intramolecular interactions contribute to the stability of the cylinder-shaped N-84. (C) 2007 Elsevier B.V. All rights reserved.