What is Stereoisomerism ? Explain the geometrical' isomerism in coordinationi compounds with suitable example.

Explanation

Stereoisomerism : Sterioisomerism is a form of isomerism in which two substances have the same composition and structure but differ in the relative spatial positions of the ligands. Geometrical isomerism
This type of isomerism arises in heteroleptic complexes due to different possible geometric arrangements of the ligands.
In square planar complexes of formula `MX_(2)L_(2)` the two ligands X may be arranged adjacent to each other in a cis isomer or opposite, to each other in a trans isomer.

Octahedral complexes of formula `[MX_(2)L_(4)]` in which two ligands X may be oriented cis or trans to each other.


Tetrahedral complexes do not show geometrical isomerism because the relative positions of the unidentate ligands attached to the central atom are the same with respect to each other.