Interhalogen Compounds

Reaction between two different halogens

Types: XX’, XX’3, XX’5 and XX’7

X – Halogen of larger size, more electropositive

X’- Halogen of smaller size

\(\frac{Radius\text{ }of\text{ }X}{Radius\text{ }of\text{ }X’}\propto No:\text{ }of\text{ }atoms\text{ }per\text{ }molecule\)


  • Direct combination.
  • Product depends on the concentrations of the reactants.
    Cl₂ + F₂ → 2ClF
    Cl₂ + 3F₂ → 2ClF₃


  • Covalent molecules
  • Diamagnetic
  • Volatile solids/liquids {except ClF which is a gas}
  • More reactive than halogens {except Fluorine} because X – X’ bond is weaker than X – X bond
  • All are polar due to difference in their electronegativity.
  • Some compounds partially ionize in solution. For example:
  • 2ICl → I⁺ + ICl²⁻


  • XX₃ – bent T shape
  • XX₅ – Square pyramidal
  • IF₇ – Pentagonal bipyramidal


  • Some interhalogens, such as BrF3, IF5, and ICl, are good halogenating
    Ex: U + 3ClF₃ → UF₆ + 3ClF
  • Iodine monochloride helps to measure the saturation of fats and oils, and as a catalyst for some reactions.
  • A number of interhalogens, including IF7, are used to form polyhalides.