Question

Explain and illustrate with an example of the following in relation to coordination compounds:

Ionisation isomerism

Answer 1

1. When coordination compounds having the same molecular formula show a difference in their ionisation behaviour and furnish different types of ions in solution, the phenomenon is called ionisation isomerism.
2. An interchange of groups between the coordination and ionic spheres gives rise to ionisation isomerism. Two different compounds with the formula Co(NH₃)₅(Br)(SO₄), for instance.
3. One example of ionisation isomerism is [Co(NH₃)₅(Br)(SO₄)] and [Co(NH₃)₅(SO₄)]Br. The structure of both the isomers [Co(NH₃)₅(Br)(SO₄)] and [Co(NH₃)₅(SO₄)]Br.
   
4. We can prepare these ionisation isomers the following way:
   \[\ce{[Co(NH3)5(SO4)]Br  -> [Co(NH3)5 (Br)]^{2+} + SO^{2-}_4]}\]
   Red Violet
   \[\ce{[Co(NH3)5(SO4)]Br  -> [Co(NH3)5(SO^{2-}_4)]^+ + Br^-}\]
   Red