Question

Which of the following coordination compounds would exhibit optical isomerism

• A. Diamminedichloroplatinum (II)
• B. Trans-dicyanobis (ethylenediamine) chromium (III) chloride
• C. Tris – (ethylenediamine) cobalt (III) bromide
• D. Pentaamminenitrocobalt (III) iodide

Answer 1

The Correct Option is C

Optical isomerism occurs in coordination compounds that do not possess a plane of symmetry or a center of symmetry. They are typically chiral, meaning they can exist as non-superimposable mirror images (enantiomers).

Let's analyze each option to determine which compound exhibits optical isomerism:

1. Diamminedichloroplatinum (II): This compound typically forms a square planar geometry around the platinum. Such configurations usually do not result in optical isomerism because they can have a plane of symmetry.
2. Trans-dicyanobis (ethylenediamine) chromium (III) chloride: The "trans" configuration implies that similar ligands are opposite each other, leading to a plane of symmetry. Therefore, it does not exhibit optical isomerism.
3. Tris-(ethylenediamine) cobalt (III) bromide: This compound forms an octahedral complex with three bidentate ethylenediamine ligands. The structure lacks a plane of symmetry and can exist as non-superimposable mirror images, hence it is optically active.
4. Pentaamminenitrocobalt (III) iodide: This compound usually has a plane of symmetry, and thus, does not show optical isomerism.

From the analysis, Tris-(ethylenediamine) cobalt (III) bromide is the only coordination compound among the given options that can exhibit optical isomerism due to its chiral configuration in an octahedral arrangement.