Explain stereoisomerism in coordination compounds.

(N/A) Stereoisomerism arises in compounds that have the same chemical formula and chemical bonds but differ in their spatial arrangement of atoms or groups.
Geometric Isomerism:
For square planar complexes of the type $[ML_4]$: This type of isomerism arises due to different possible arrangements of ligands in heteroleptic complexes.
In complexes with coordination number $4$,square planar complexes with the formula $[MX_2L_2]$ exhibit two isomers: the $cis$ isomer,where two $X$ ligands are adjacent to each other,and the $trans$ isomer,where they are opposite to each other.
Other square planar complexes of the type $[MABXL]$ can also show three isomers (two $cis$ and one $trans$). This type of isomerism is not possible in tetrahedral geometry.
For octahedral complexes of the type $[ML_6]$: In complexes with the formula $[MX_2L_4]$,the two $X$ ligands can be oriented in either $cis$ or $trans$ positions relative to each other.
This type of isomerism also arises in complexes with the formula $[MX_2(L-L)_2]$ when bidentate ligands $(L-L)$ (e.g.,$en = NH_2CH_2CH_2NH_2$) are present.
Another type of geometric isomerism arises in octahedral complexes of the type $[Ma_3b_3]$,such as $[Co(NH_3)_3(NO_2)_3]$. If the three donor atoms of the same ligands occupy adjacent corners of an octahedral face,we obtain the facial $(fac)$ isomer.