Aromaticity and hydrogen storage capability of planar N6 4-and N4 2 rings.

Abstract

Theoretical investigation on planar N64- and N42- rings has been performed. The aromaticity of the rings has been analyzed through their nucleus independent chemical shift (NICS) values as well as the σ- and π-contribution of the Z-component of the induced magnetic field. Counter to a previously reported result [Chem. Phys. Lett. 432 (2006) 331], the N6 4- ring is found to be a local minimum and aromatic with planar D6h symmetry. The N6 2- ring exhibits conflicting aromaticity like AlN44-. Both the N64- and N42- rings can be stabilized in presence of suitable counter cations and systems like N 6Ca2 and N4Li2 can trap molecular hydrogen.