Question

Assertion (A) $AlCl _{3}$ exists as a dimer through halogen bridged bonds.
Reason (R) $AlCl _{3}$ gets stability by accepting electrons from the bridged halogen.

• A. Both (A) and (R) are true and (R) is the correct explanation of (A)
• B. Both (A) and (R) are true but (R) is not the correct explanation of (A)
• C. (A) is true, but (R) is false
• D. (A) is false, but (R) is true

Answer 1

Answer: (A)

$AlCl _{3}$ exists as a dimer through halogen bridged bonds. It is an electron deficient species. In order to complete the octet of aluminium, the molecule dimerises to form $Al _{2} Cl _{6}$ in which electrons are added to aluminium octet through coordinate bond by chlorine atom.



$ Al _{2} Cl _{6}$ forms from two $AlCl _{3}$ molecules. Since, two $Cl$ atoms can act as a "bridge".