Question

Explain the geometrical isomerism of the octahedral complex of the type [M(AA)₂B₂]^n± with a suitable example.

Answer 1

1. Consider an octahedral complex of metal M with coordination number six and a bidentate ligand AA and monodentate ligand B having molecular formula [M(AA)₂B₂]^n± 
2. Bidentate ligand AA has two identical coordinating atoms.
3. When two bidentate AA ligands and two "B" ligands are positioned next to each other, a cis-isomer is produced.
4. When two B and two AA ligands are positioned opposite each other, a trans-isomer is produced.
5. For example, consider a complex [Co(en)₂Cl₂]⁺ 

(a)

(b)