Superatom Compounds, Clusters, and Assemblies:  Ultra Alkali Motifs and Architectures

It has recently been demonstrated that chosen clusters of specific size and composition can exhibit behaviors reminiscent of atoms in the periodic table and hence can be regarded as superatoms forming a third dimension. An Al(13) cluster has been shown to mimic the behavior of halogen atoms. Here, we demonstrate that superatom compounds formed by combining superhalogens (Al(13)) with superalkalis (K(3)O and Na(3)O) can exhibit novel chemical and tunable electronic features. For example, Al(13)(K(3)O)3 is shown to have low first and second ionization potentials of 2.49 and 4.64 eV, respectively, which are lower than alkali atoms and can be regarded as ultra alkali motifs. Al(13)K(3)O is shown to be a strongly bound molecule that can be assembled into stable superatom assemblies (Al(13)K(3)O)n with Al(13) and K(3)O as the superatom building blocks. The studies illustrate the potential of creating new materials with an unprecedented control on physical and electronic properties.