Design of a Novel Series of Hetero-Binuclear Superhalogen Anions MM′X(4) (−) (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(4) (−) (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(4) (−) 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.