Isomerism

(i) Enantiomers: Enantiomers are pairs of molecules that are non-superimposable mirror images of each other. They have identical physical properties but differ in their interaction with plane-polarized light and in the way they interact with other chiral substances. For example, the right- and left-handed forms of a chiral molecule are enantiomers.

(ii) Racemic mixture: A racemic mixture is a mixture containing equal amounts of two enantiomers of a chiral compound. In a racemic mixture, the optical activities of the enantiomers cancel each other out, resulting in no net optical rotation.

Possible Isomers of the Complex

The complex ion:

can have two types of geometric isomers: cis and trans.

• Cis isomer: Both Cl⁻ ions are adjacent to each other.
• Trans isomer: The Cl⁻ ions are opposite each other.

Here, “en” stands for ethylenediamine, which is a bidentate ligand. The arrangement of these ligands and the chloride ions around the cobalt center gives rise to these two possible geometric isomers.