Explain different types of isomerism exhibited by coordination compounds, giving suitable examples.

I) Structural isomerism: Two (or) More compounds having same molecular formula, but different structural arrangements are called structural isomerism.
Structural isomerism is mainly 4 types.
i) Ionization isomerism: Compounds having same molecular formula but give different ions in a solution is called ionisation isomerism.
$\mathrm{ }\mathbf{Ex}\mathbf{.}\mathrm{ }\left[\mathrm{Co}{\left({\mathrm{NH}}_3\right)}_5\mathrm{Br}\right]{\mathrm{SO}}_4,\left[\mathrm{Co}{\left({\mathrm{NH}}_3\right)}_5{\mathrm{SO}}_4\right]\mathrm{Br}$
ii) Hydrated isomerism: Compounds having same formula, but different number of water molecules attached to metal atom (or) ion as ligands are called Hydrated isomerism.
$\mathbf{\text{ Ex.}}\left[\mathrm{Cr}{\left({\mathrm{H}}_2\mathrm{O}\right)}_6\right]{\mathrm{Cl}}_3,\left[\mathrm{Cr}{\left({\mathrm{H}}_2\mathrm{O}\right)}_5\mathrm{Cl}\right]{\mathrm{Cl}}_2\cdot {\mathrm{H}}_2\mathrm{O}$
iii) Linkage isomerism: It is shown by the compounds containing ambidentate ligand which can attach to the metal through more than one Donar atom.
$\mathbf{\text{ Ex.}}\left[\mathrm{Co}\left({\mathrm{NO}}_2\right){\left({\mathrm{NH}}_3\right)}_5\right]{\mathrm{Cl}}_2\text{, }\left[\mathrm{Co}\left(\mathrm{ONO}\right){\left({\mathrm{NH}}_3\right)}_5\right]{\mathrm{Cl}}_2$
iv) Coordination isomerism: Compounds having same formula, but two central metal atoms (or) ions exchanges their ligands are called coordination isomerism.
$\mathbf{Ex}.\left[\mathrm{Co}{\left({\mathrm{NH}}_3\right)}_6\right]\left[\mathrm{Cr}(\mathrm{CN}{)}_6\right]\text{, }\left[\mathrm{Co}(\mathrm{CN}{)}_6\right]\left[\mathrm{Cr}{\left({\mathrm{NH}}_3\right)}_6\right]$
II) Stereo isomerism: compounds having same formula and structure but different spatial arrangements of ligands around central metal atom (or) ion.
Stereo isomers are mainly two types.
i) Geometrical isomerism: When two identical groups occupy adjacent positions, the isomers are called cis isomers. When they are arranged opposite to one another that isomers are called trans isomers. Square planar complexes of MA₂X₂ ,MABX₂ etc., octahedral complexes of MA₄X₂ and MA₃X₃ exhibits Geometrical isomerism.
$\mathbf{Ex}:\left[\mathrm{Pt}{\left({\mathrm{NH}}_3\right)}_2{\mathrm{Cl}}_2\right]$

ii) Optical isomerism: If two isomers are non-super imposable, mirror images to each other they are called optical isomers and the process is called optical isomerism.
Octahedral complexes with 2 (or) 3 bidentate ligands shows optical isomerism.
$\mathbf{Ex}\mathbf{.}{\left[{\mathrm{CoCl}}_2(\mathrm{en}{)}_2\right]}^{+},{\left[\mathrm{Co}(\mathrm{en}{)}_3\right]}^{+3}$