Doubly Charged Superhalogen Systems

In this chapter, we present an extension of the superhalogen concept by incorporating di-anions. Although achieving stability toward electron detachment for di-anions is challenging, we have made an intriguing discovery regarding the sufficient stability exhibited by polynuclear species. We have studied this phenomenon in various systems such as MF₆ ^2– (M = Si, Ge, Sn, Pb), TeF₈ ^2–, AlF₅ ^2–, Al₂F₈ ^2–, Si₂F₁₀ ^2–, Si₃F₁₄ ^2– and B₁₂F₁₂ ^2–. The effective design strategies used for constructing singly charged superhalogens have proven to be equally successful in the development of doubly charged superhalogens. These strategies involve the utilization of ligands with high ionization potentials, the nonbonding nature of HOMO orbital(s) and maximizing the number of ligands. Specifically, we have utilized fluorine as the ligand due to its exceptional effectiveness. The study uses methods such as global minimum search and energy calculations to determine the VDEs and ADEs of these di-anions. The results demonstrate the high VDEs and ADEs exhibited by these di-anions, indicating their characteristic superhalogen properties. Overall, this research contributes to the understanding of superhalogens and offers valuable insights for the development of new superhalogen systems.