Stability, Reactivity, and Aromaticity of Compounds of a Multivalent Superatom

In this communication we analyze the stability, reactivity and possible aromatic behavior of two recently reported clusters (Reveles J. U.; Khanna S. N.; Roach P. J.; Castleman A. W. jr. Proc. Natl. Acad. Sci, 2006, 103, 18405), viz., Al7C- and Al7O- in the light of the principles of the maximum hardness and minimum electrophilicity as well as the nucleus independent chemical shift values.