A theoretical study on the stability of N15+ cluster

Ab initio (MP2) and density functional theory (DFT) methods have been used to examine three isomers of the N15+ cluster with the 6-31G* basis set. The most stable isomer is the trans structure (CS), containing one aromatic N5 ring and two N5 side chains. The decomposition pathways of the three isomers were studied at the B3LYP/6-31G* level of theory. Relative energies were refined at the level of B3LYP/6-311G(3df,2p)//B3LYP/6-31G* + ZPE (B3LYP/6-31G*). The decomposition reactions of the global minimum prefer side-chain fission, with barriers of 9.3 and 12.0 kcal mol−1 for N2 and N5+ (C2v) fission reactions, respectively. The ring breaking reaction has a barrier of 19.4 kcal mol−1. The corresponding side-chain fission barriers for the second structure (C2v), which is a cis isomer, are predicted to be 9.3 kcal mol−1 and 12.1 kcal mol−1, respectively. The barrier height for breaking the center ring of the three connected N5 rings of the third structure (C2) is predicted to be 8.0 kcal mol−1.