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Lewis Acid/Base Interaction Matrix Database

Type 2 Lewis Acid/Base Complexation Chemistry

George Olah Superacids

Protons do not complex efficiently with complex anion Lewis bases as the proton must disrupt the anion’s high symmetry HOMO when a 1:1 complex forms. Hence, the resulting complex is a very powerful proton donor.

Complexes are ionic/highly polar covalent.


Superacids are neutral.


Proton plus complex anion complexes must be prepared in ‘exotic’ solvents such as liquid SO2 and where the complex anion has fluoride ion ligands.

George Olah's 'magic acid' is prepared by mixing antimony pentafluoride and fluorosulfonic acid. Hydrocarbon wax will dissolve in a magic acid solution.

Such complexes are the strongest Brønsted acids known. Super [Brønsted] acids, 'superacids', have pKa values in the region -15 to -25, ie they are up to 20 orders of magnitude more [Brønsted] acidic than sulfuric acid.

Superacids are able to fully protonate all Lewis base organic functional groups (as opposed to protonating a low equilibrium concentration). Alkenes, benzene, carbonyls and nitro functional groups are all protonated by superacids. For example:

Read more on the Wikipedia superacid page.

Congeneric Series: Few series.
Type 2 Lewis acid/base complex (generic)
Fluoroantimonic acid

more here
Hexafluorosilicic acid (aqueous)

more here
Magic acid

more here
Tetrafluoroboric acid

more here
Interactions and reactions classified as:
      1 +1 1
      1 +1 1
      1 +1 1 +1
      1 +1 1
      1 +1 1 +1

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Poster Nucleophiles & Bases

© Mark R. Leach 1999 –

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