Explain different types of structural isomerism in coordination compounds.

(N/A) $i$. Ionisation isomerism: This form of isomerism 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. Hence,there is an exchange of ligands between the coordination entity and the ionisation sphere.
The compounds showing ionisation isomerism give different ions in aqueous solution.
For example: $[Co(NH_3)_5(SO_4)]Br$ and $[Co(NH_3)_5Br]SO_4$.
$ii$. Hydrate isomerism (Solvate isomerism): This form of isomerism exists where water is involved as a solvent. When water molecules are interchanged between the coordination sphere and the ionisation sphere,the resulting isomers are called hydrate (solvate) isomers.
For example:
$[Cr(H_2O)_6]Cl_3 \Rightarrow \text{Violet}$
$[Cr(H_2O)_5Cl]Cl_2 \cdot H_2O \Rightarrow \text{Grey-green}$
$[Cr(H_2O)_4Cl_2]Cl \cdot 2H_2O \Rightarrow \text{Green}$
$iii$. Linkage isomerism: This isomerism arises in a coordination compound containing an ambidentate ligand. $A$ simple example is provided by complexes containing the thiocyanate ligand $(NCS^-)$ which may bind either through sulphur or by nitrogen.
For example:
$1$. $[Cr(SCN)(H_2O)_5]^{2+}$ and $[Cr(NCS)(H_2O)_5]^{2+}$
$2$. $[Co(ONO)(NH_3)_5]^{2+}$ and $[Co(NO_2)(NH_3)_5]^{2+}$
Jorgensen discovered such behaviour in the complex $[Co(NH_3)_5(NO_2)]Cl_2$,which is obtained in a red form,in which the nitrite ligand is bound through oxygen $(-ONO)$,and as a yellow form,in which the nitrite ligand is bound through nitrogen $(-NO_2)$.
$iv$. Coordination isomerism: This type of isomerism arises from the interchange of ligands between cationic and anionic entities.