Fluoroantimonic acid is the strongest acid created so far. It's formula is HSbF6.
Fluoroantimonic acid (HSbF6) is a mixture of hydrogen fluoride and antimony pentafluoride in various ratios. The 1:1 combination forms the strongest known superacid, which has been demonstrated to protonate even hydrocarbons to afford carbocations and H2.[2]
The reaction of hydrogen fluoride (HF) and SbF5 is exothermic. HF, being an Lewis base, attacks the molecules of SbF5 to give an adduct. In the fluoroantimonic molecule, the anion is coordinated to the hydrogen, although the anion is formally classified as noncoordinating, because it is both a very weak nucleophile and a very weak base.
Despite the proton being called effectively "naked," it is in fact always attached to a fluorine through a very weak dative bond, similar to the hydronium cation.[3] However, the weakness of this bond accounts for the system's extreme acidity. Fluoroantimonic acid is 2×1019 (20 quintillion) times stronger than 100% sulfuric acid.[4]
