Question

The type of isomerism shown by the complex [CoCl₂(en)₂] is

• A. Geometrical isomerism
• B. Ionization isomerism
• C. Coordination isomerism
• D. Linkage isomerism

Answer 1

The Correct Option is A

To determine the type of isomerism shown by the complex [CoCl₂(en)₂], let's first understand the complex and its components.

• The complex [CoCl₂(en)₂] consists of a cobalt metal center (Co), two chloride ions (Cl^-), and two ethylenediamine (en) ligands.
• Ethylenediamine (en) is a bidentate ligand, which means it can form two bonds with the central metal atom.
• The cobalt ion is in a coordination number of 6, often leading to an octahedral complex arrangement.

Now, let's analyze the possible isomerism types:

1. Geometrical Isomerism:
   • This type of isomerism arises in coordination compounds when the spatial arrangement of ligands results in different configurations.
   • For an octahedral complex like [CoCl₂(en)₂], geometrical isomerism can occur as the arrangement of the chloride ions and en ligands can differ around the cobalt center.
   • The two main possibilities for such an arrangement in this complex are cis isomer (where the Cl^- ligands are adjacent) and trans isomer (where the Cl^- ligands are opposite each other).
2. Ionization Isomerism:
   • This occurs when complex ions exchange their ligands with ions outside the coordination sphere.
   • Since [CoCl₂(en)₂] does not have ions available to swap with external ions, ionization isomerism isn't applicable.
3. Coordination Isomerism:
   • This type involves the exchange of ligands between two coordination complexes.
   • Here, there is only one metal center, not multiple complexes exchanging ligands.
4. Linkage Isomerism:
   • This exists when a ligand can coordinate to the metal center in different ways/forms.
   • In this complex, ethylenediamine is a bidentate ligand coordinating through the nitrogen atoms only, leaving no scope for linkage isomerism.

Conclusion: The complex [CoCl₂(en)₂] shows geometrical isomerism due to the spatial arrangement of ligands around the cobalt center, which allows for the formation of cis and trans isomers.