Question

Explain coordination and ionisation isomerism with suitable examples?

Answer 1

Coordination isomerism:
Ligands are interchanged between cationic and anionic entities of different metal ions present in the complex. The isomers have same molecular formula.
For example, in $\left[Co\right(N{H}_3{)}_6\left]\right[Cr\left(CN{)}_6\right]$, ammonia ligands are bound to $Co$ and cyano ligands are bound to $Cr$. Whereas in $\left[Cr\right(N{H}_3{)}_6\left]\right[Co\left(CN{)}_6\right]$, ammonia ligands are bound to $Cr$ and cyano ligands are bound to $Co$.
Ionisation isomerism ( ion-ion exchange isomerism ):
There is exchange of ions inside and outside co-ordination sphere. The isomers have same molecular formula but produce different ions in solution.
Example: Red violet colored $\left[Co\right(N{H}_3{)}_{5}S{O}_4]Br$ produces $\left[Co\right(N{H}_3{)}_{5}S{O}_4{]}^{+}+B{r}^{-}$ ions in solution whereas red colored $\left[Co\right(N{H}_3{)}_{5}Br]S{O}_4$ produces $\left[Co\right(N{H}_3{)}_{5}Br{]}^{2+}+S{O}_4^{2-}$ ions in solution.