How can Fe + be both a lewis acid and A bronsted acid ?

asked by @bja1 • over 1 year ago • Organic Chemistry • 5 pts
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1 answer

Hey there! Iron is definitely a Lewis Acid because it fits the definition as a species that accepts an electron pair (i.e., an electrophile) and will have vacant orbitals.

Here is a comprehensive breakdown of some other scenarios where we could classify a compound as a Lewis Acid:

  • All cations are Lewis acids since they are able to accept electrons (e.g., Cu2+, Fe2+, Fe3+)
  • An atom, ion, or molecule with an incomplete octet of electrons can act as an Lewis acid (e.g., BF3, AlF3)
  • Molecules where the central atom can have more than 8 valence shell electrons can be electron acceptors, and thus are classified as Lewis acids (e.g., SiBr4, SiF4)
  • Molecules that have multiple bonds between two atoms of different electronegativities (e.g., CO2, SO2)

Now I'm not quite sure that Iron would fit the definition of a bronsted Acid in a common scenario. It would have to have a proton to donate.

If you would give me more context I can give you a more direct answer! However to distinguish between the two you should use other compounds such as Carboxylic Acid or Water which can be both a Lewis and Bronsted Acid.

I hope this helped!

answered by @chris • over 1 year ago