Question

Explain ionization isomers with suitable example in complexes.

Answer 1

Definition:

Ionization isomerism occurs in coordination compounds when two isomers produce different ions in solution, even though they have the same overall composition. This happens due to the exchange of groups between the coordination sphere and the ionization sphere.

Key Idea:

• The ligands inside the coordination sphere may exchange places with counter-ions outside the sphere.
• This leads to compounds with the same formula but different ions in solution.

Example:

Consider the following two complexes: \[ [Co(NH_3)_5SO_4]Br \quad \text{and} \quad [Co(NH_3)_5Br]SO_4 \]

- The first complex in aqueous solution gives: \[ [Co(NH_3)_5SO_4]Br \;\;\rightarrow\;\; [Co(NH_3)_5SO_4]^+ + Br^- \] Hence, it produces \(Br^-\) ions in solution.

- The second complex in aqueous solution gives: \[ [Co(NH_3)_5Br]SO_4 \;\;\rightarrow\;\; [Co(NH_3)_5Br]^ {2+} + SO_4^{2-} \] Hence, it produces \(SO_4^{2-}\) ions in solution.

Final Answer:

Ionization isomers are coordination compounds that yield different ions in solution. Example: \[ [Co(NH_3)_5SO_4]Br \quad \text{and} \quad [Co(NH_3)_5Br]SO_4 \] are ionization isomers.