Cl©Li5Cl5−: A Star-like Superhalogen Anion Featuring a Planar Pentacoordinate Chlorine at the Center

Among the known planar pentacoordinate atoms, chlorine is missing due to its large radius and high electronegativity. Herein, we report the first star-like superhalogen anion <i>D</i>_5<i>h</i> Cl©Li₅Cl₅^- (<b>1</b>), which contains a planar pentacoordinate chlorine (ppCl) at the center. Computer structural searches and high-level calculations reveal that <b>1</b> is a true global minimum (GM) on the potential energy surfaces. Molecular dynamics simulations indicate it is kinetically stable against isomerization or decomposition. Although detailed chemical bonding analyses reveal one delocalized 6c-2e σ bond over the Cl©Li₅ central unit and five delocalized 3c-2e σ bonds along the periphery, while aromaticity has very little beneficial effect on stability, instead, ionic interaction dominates the stability of the system. More encouragingly, with the large HOMO-LUMO energy gap of 7.66 eV and vertical detachment energy of 7.87 eV, the highly chemically inert <b>1</b> can be viewed as a typical superhalogen anion and is possible to be synthesized and characterized in future experiments.