A type of isomerism in co-ordination compound that arises when the counter ion in a complex salt is itself a potential ligand and can displace a ligand which can then become a counter ion
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Ionisation Isomerism
Coordination compounds show two main kinds of isomerism: stereoisomerism (geometrical and optical) and structural isomerism. Structural isomers have different bonds and are of four types: linkage, coordination, ionisation and solvate isomerism.
In ionisation isomerism the counter ion and a ligand change places, so the two isomers give different ions in solution.
The first gives a precipitate of AgBr with \( \ce{AgNO3} \); the second gives a precipitate of \( \ce{BaSO4} \) with \( \ce{BaCl2} \).
NCERT (2026-27 edition):
Ionisation Isomerism
