Question

The type of isomerism shown by the complex $[CoCl_2(en)_2]$ is

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

Answer 1

The Correct Option is B

The given complex is [CoCl_2(en)_2], where 'en' stands for ethylenediamine, a bidentate ligand. Let's analyze the type of isomerism it exhibits.

Understanding Isomerism in Coordination Compounds:

Isomerism is a phenomenon where compounds have the same chemical formula but different structural or spatial arrangements. Common types of isomerism in coordination chemistry include:

• Linkage Isomerism: Occurs when a ligand can coordinate to a metal atom/ion through different atoms.
• Geometrical Isomerism: Deals with the spatial arrangement of ligands, most commonly seen in octahedral or square planar complexes.
• Ionization Isomerism: Occurs when there is an exchange of ions inside or outside the coordination sphere.
• Coordination Isomerism: Happens when the composition of the coordination spheres in a complex salt is different.

Analyzing the Given Complex [CoCl_2(en)_2]:

1. The complex [CoCl_2(en)_2] contains a cobalt ion coordinated by two chloride ions and two ethylenediamine ligands.

2. Ethylenediamine is a bidentate ligand, which means it occupies two coordination sites on the cobalt center.

3. The geometry around the cobalt is octahedral, which is a common geometry for complexes with coordination number 6.

Identification of Isomerism:

- Since we have two different types of monodentate (Cl^-) and bidentate ligands (en) in the complex, geometrical isomerism is possible. Specifically, we can have cis and trans isomers based on the relative positions of the chloride ions.

Conclusion:

In the complex [CoCl_2(en)_2], the type of isomerism exhibited is Geometrical Isomerism. This is due to the possible arrangement of the chloride ions in either cis or trans positions relative to each other within an octahedral geometry.