Design of a Novel Series of Hetero-Binuclear Superhalogen Anions MM'X (M = Li, Na; M' = Be, Mg, Ca; X = Cl, Br).

A series of hetero-binuclear superatom motifs involving chloride/bromide ligands, that is, MM'X (M = Li, Na; M' = Be, Mg, Ca; X = Cl, Br) anions, have been characterized by using many-body perturbation theory calculations. Large vertical electron detachment energies (VDEs, 5.470-6.799 eV) confirm the superhalogen identity of these anions. A larger VDE value can be obtained by introducing small M or large M' central atoms and small halogen ligand atoms. Thus, one isomer of LiCaCl possesses the largest VDE value. Besides, when the extra electron is shared by all ligand atoms or three bridging ligand atoms, the isomers have relatively larger VDE values.