Metal Cluster Electrides: A New Type of Molecular Electride with Delocalised Polyattractor Character

Electrides are ionic substances containing isolated electrons. These confined electrons are topologically characterised by a quasi‐atom, that is, a non‐nuclear attractor (NNA) of the electron density. The electronic structure of the octahedral 4A1g Li6+ and 5A1g Be6 species shows that these species have a large number of NNAs. These NNAs have highly delocalised electron densities and, as a result, the chemical bonding pattern of these systems is reminiscent of that in solid metals, in which metal cations are surrounded by a “sea” of delocalised valence electrons. We propose the term metal cluster electrides to refer to this new class of compounds. In this study, we establish a computational protocol to identify, characterize, and design metal cluster electrides and we elucidate the intricate bonding patterns of this particular type of species. Octahedral cluster electrides: Metal cluster electrides are a new class of electrides with a large number of non‐nuclear attractors (NNAs), and most of the valence electrons are located in these NNAs. The chemical bond in these species is reminiscent of those in metallic crystals. Octahedral Li6+ (S=3/2) and Be6 (S=2) (see graphic) are reported to belong to this new class of electrides.