Question

Write the optically active isomers of [Co(en)₂Cl₂]⁺.

Answer 1

1. Optical isomers are compounds with the identical number and type of atoms, bonds, and groupings. They have non-superimposable mirror images, also known as enantiomers. Chiral molecules or ions refer to optical isomers.
2. The cis-isomer, in which both Cl⁻ ligands are adjacent to each other, can exist as two non-superimposable mirror image forms known as the Λ (lambda) and Δ (delta) isomers.
3. Trans-isomer of [Co(en)₂Cl₂]⁺ is optically inactive because it is superimposable on its mirror image (has a plane of symmetry).
4. These two forms are enantiomers and are optically active, meaning they rotate plane-polarized light in opposite directions.
5. The complex [Co(en)₂Cl₂]⁺ is in the composition [M(AA)₂B₂] type and thus it shows optical isomerism. It is cis form can be resolved into two optically active isomers as it does not have any plane of symmetry. On the other hand the trans isomer has a plane of symmetry and hence shows no optically active form.