| Abstract
| - The relative stabilities of nonisomers are investigated. Twenty-two species of nitrogen cage molecules N2n(N6 (D3h), N8 (Oh), N10 (D5h), N12 (D6h), N12 (D3d), N16 (D4d), N18 (D3h), N20 (Ih), N24 (D3d), N24 (D4h), N24(D6d), N30 (D3h), N30 (D5h), N32 (D4d), N36 (D3d), N40 (D4h), N42 (D3h), N48 (D4d), N48 (D3d), N54 (D3h), N56(D4h), and N60 (D3d)), which are divided into four sets, have been studied in detail. The geometries and varietiesof energies are examined extensively, and NBO analysis and AIM analysis are applied to investigate thebonding properties of the cage molecules. The introducing of the concept of “layer” can well assist in explainingwhy one nonisomer molecule is more stable than another one. The results show that the lengths of bonds, onboth sides of which are five-membered rings (referred to as pentagons), are the shortest and the orbital energiesare the lowest. The nonlocalized electron numbers of orbitals, on at least one side of which is a triangle, arethe greatest. Pentagons play a major role in the stability of a cage molecule, and the three-membered rings(referred to as triangles) play the second one. The layers in nitrogen cage molecules also contribute to therelative stabilities.
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