A computer-aided quantum chemical study of the N15- cluster

Ab initio (RHF, MP2) and Density Functional Theory (DFT) methods have been used to examine six isomers of the N-15(-) cluster with the 6-31+G* basis set. Different from the known odd-numbered anionic N-7(-), N-9(-), and N-11(-) clusters, in which the open-chain structures are the most stable species, the most stable N-15(-) isomer is structure 1 (C-1), which may be considered as a complex between the fragments cyclic N-5(-) (D-5h) and staggered N-10 (D-2d). The decomposition pathways of structure 2 (C-S), containing two aromatic N-5 rings connected by a N-5 chain, and the open-chain structure 3 (C-2v) were studied at the B3LYP/6-31+G* level of theory. Relative energies were refined at the level of B3LYP/6-311+G(3df, 2p)//B3LYP/6-31+G*+ZPE (B3LYP/6-31+G*). The barriers for N-2 and N-5(-) (D-5h) fission reactions for structure 2 are predicted to be 18.2 and 14.2 kcal mol(-1), respectively. The corresponding N-2+N-3(-) fission barrier for structure 3 is predicted to be 11.2 kcal mol(-1). Supplementary material is available for this article if you access the article at http://dx.doi.org/10.1007/s00894-003-0118-0. A link in the frame on the left on that page takes you directly to the supplementary material.