CF_4-<i>n</i>(SO₃)<i>_n</i> (<i>n</i> = 1–4): a new series of organic superhalogens

Superhalogens are species having higher electron affinity (EA) or vertical detachment energy (VDE) than those of halogen atoms. CF4 is a molecule having no positive EA or VDE. In the quest for new organic superhalogens, we substitute SO3 in the place of F in CF4 successively and study the resulting CF4-n(SO3)n (n = 1–4) neutral molecules and their anions using density functional theory and quantum theory of atoms in molecule at the ωB97xD/6-311 + G(d) and B3LYP/6-311 + G(d) levels, respectively. The EA of CF4-n(SO3)n and VDE of their anions, being greater than 5 eV, suggest that all these molecules behave as superhalogens. There is significant structural relaxation in C(SO3)4 molecule, leading to the remarkably high VDE of corresponding anions. The superhalogen properties have been explained on the basis of the electronic charge delocalisation over SO3 moieties. We believe that these findings will add a new chapter in the exploration of organic superhalogens.