On the Aluminum Cluster Superatoms acting as Halogens and Alkaline-earth Metals

It is shown that a new class of super-polyhalides can be formed by combining the Al$_{13}$ super-halogen with the conventional halogen, I. Experimental reactivity studies demonstrate that the new super-polyhalides, Al$_{13}$I$_{x}^{-}$, exhibit pronounced stability for even numbers of I atoms. Theoretical investigations probing the geometry and the electronic structure reveal that the enhanced stability is associated with pairs of I atoms occupying the on-top sites around the Al$_{13}^{-}$ core. We also demonstrate another series, Al$_{14}$I$_{x}^{-}$, that exhibits stability for odd numbers of I atoms. It is shown that this series can be described as consisting of an Al$_{14}$I$_{3}^{-}$ core upon which the I atoms occupy on-top locations around the Al atoms. The potential synthetic utility of superatom chemistry built upon these motifs will be addressed.