HCF4−n(SO3)n (n=1–4): Designing new series of organic superacids

Abstract

Superacids are systems that exhibit higher acidity compared to extremely strong mineral acid, i.e. 100% pure sulphuric acid (H2SO4). They can be designed by the protonation of appropriate superhalogen anions. Superhalogens possess higher electron affinity (EA) than halogens. Most recent examples include CF[Formula: see text], which behave as superhalogens for [Formula: see text]. In this work, we studied the protonation of CF[Formula: see text] using density functional theory calculations at the B3LYP/6-311[Formula: see text] level. The Gibbs’ free energies of deprotonation ([Formula: see text]) values of the resulting protonated complexes, HCF[Formula: see text] for [Formula: see text]–4; are either lower or nearly equivalent to that of H2SO4 ([Formula: see text][Formula: see text]kcal/mol). This suggests that all these protonated complexes exhibit superacidic behavior. Notably, the HC[Formula: see text] compound undergoes significant structural relaxation, leading to a remarkably less [Formula: see text] value. Our findings should enrich the literature with a new series of superacids and motivate further studies to explore novel organic superacids.