SLi 4 X 3 - (X = Cl, Br, I)：fan-shaped superhalogen anions featuring planar tetracoordinate sulfur

Abstract

The first planar tetracoordinate sulfur (ptS) SLi 4 X 3 - (X = Cl, Br, I) mono-anionic clusters have been designed by using the "partially eliminating after isoelectonicreplacing" strategy, inspired the previously reported ptF FLi 4 X 4 - (X = Cl, Br, I) clusters.They are true ptS global minima featuring the fan-shaped structures with a SLi 4 core and three peripheral X bridges. They are also dynamically stable at room temperature, based on Born-Oppenheimer molecular dynamics simulations. Chemical bonding analyses indicate that the ptS centers are mainly ionically connected to the Li ligands, due to their significant difference in electronegativity. Encouragingly, the exotic SLi 4 X 3 - (X = Cl, Br, I) clusters have the ground-state vertical detachment energies of 4.33, 4.60, 4.90 eV at the OVGF/def2-TZVPP level, respectively, which are greater than the electron affinity of chlorine atom (3.61 eV) and can be considered as the superhalogen anions. The current work not only presents a new strategy for designing ptS species but also builds an important link between ptS and superhalogens.