An isomeric study of N5+, N5, and N5-:: a Gaussian-3 investigation

An isomeric study for N-5, N-5(+), and N-5(-) has been carried out using the Gaussian-3 (G3) method. At the MP2(FU)/6-31G(d) level, six N-5, five N-5(+) and four N-5(-) isomers are identified. Of these 15 species, 12 of them have not been reported previously. The most stable N-5 isomer is a weak N-2...N-3 complex with C-2v symmetry, while the most stable N-5(-) isomer is also a weak N-2...N-3(-) complex with the same symmetry. The most stable species for N-5(+) has an open-chain structure with C-2v symmetry, which has been synthesized and characterized spectroscopically. Natural bond orbital (NBO) analysis suggests that the stability of this cation is enhanced by hyperconjugation. (C) 2000 Elsevier Science B.V. All rights reserved.