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

Preparation:

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

Properties:

• 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⁻

Structure:

•  XX₃ - bent T shape
• XX₅ - Square pyramida
•  IF₇ - Pentagonal bipyramidal

Uses:

• Some interhalogens, such as BrF₃, IF₅, and ICl, are good halogenating agents.
  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.