Write a note on geometrical isomerism.

Explanation

Geometrical isomerism. It occurs in disubstituted complexes with co-ordinates number four or six, having square planar or octahedral arrangement respectively. It does not occur in tetraliedral complexes. When similar groups are adjacent to each other, it is called cis isomer, whereas when similar groups are opposite to each other, it is called trans isomer.
Examples. (i) `[Pt(NH_3)_2Cl_2]` - a square planer complex exists in two forms as :

(ii) As octahedral complex `[Co(NH_3)_4Cl_2]^(+)` exists in two forms as: