Face-Sharing Homo- and Hetero-Bitetrahexahedral Superatomic Molecules M1M2@Li20 (M1/M2 = Ti and W).

Abstract

Superatoms, being a class of clusters with chemical behavior similar to atoms, can be used as building blocks for constructing novel functional materials. Here, superatomic molecules M1M2@Li20 (M1/M2 = Ti and W) are built with our recently discovered tetrahexahedral superatoms Ti@Li14 and W@Li14. A low-energy face-sharing bi-tetrahexahedral structure with a high symmetry of D6 h is identified by global minimum structure search and frequency calculations. The number of shared Li atoms amounts to 6, which is rarely seen before. Molecular orbital and chemical bonding analyses reveal that although isolated superatoms Ti@Li14 and W@Li14 are nonmagnetic, Ti2@Li20 is an open-shell superatomic molecule with a magnetic moment of 2 μB, whereas for W2@Li20, the electronic shell remains closed. In both Ti2@Li20 and W2@Li20, a quadruple superbonding between superatoms is found. Interestingly, an assembly of two hetero-tetrahexahedral superatoms Ti@Li14 and W@Li14 also gives a face-sharing bi-tetrahexahedral structure but with a notable dipole moment. This study provides a basic understanding for the superatomic bonding of Ti@Li14 and W@Li14, which may aid their application in developing multi-superatom molecules or even bulk crystals.