Question

Which one of the following octahedral complexes will not show geometric isomerism? (A and B are monodentate ligands)

• A. [MA2B4]
• B. [MA3B3]
• C. [MA4B2]
• D. [MA5B]

Answer 1

Answer: (D)

[MA5B]

Answer 2

Geometric isomerism occurs in octahedral complexes when there are at least two different types of ligands or when there is a bidentate ligand present. Geometric isomerism is not possible when all ligands are the same type and are monodentate. In such cases, the ligands can only occupy adjacent positions in the octahedral coordination sphere.
Among the options given:
(1) [MA2B4] has two types of ligands (A and B), so it can exhibit geometric isomerism.
(2) [MA3B3] has two types of ligands (A and B), so it can exhibit geometric isomerism.
(3) [MA4B2] has two types of ligands (A and B), so it can exhibit geometric isomerism.
(4) [MA5B] has only one type of ligand (A), and they are all monodentate. Therefore, it will not show geometric isomerism.

So, the correct answer is (D): [MA5B].