Octahedral Complexes and Geometric Isomerism

Octahedral complexes are those compounds in which a central metal ion is surrounded by six ligands occupying the corners of an octahedron. These ligands can be either monodentate or polydentate, and they can be arranged in different ways around the metal ion. The arrangement of ligands around the metal ion can give rise to different isomers, which are called geometric isomers. Geometric isomers have the same molecular formula and the same connectivity but differ in their spatial arrangement.

Factors Contributing to Geometric Isomerism

The factors contributing to geometric isomerism are:

- The presence of different types of ligands
- The arrangement of ligands around the metal ion
- The presence of chiral ligands or ligand planes

Octahedral Complexes and Geometric Isomerism

In octahedral complexes, geometric isomerism can occur when there are different types of ligands present or when the ligands are arranged in a specific way. The different types of isomers that can be formed are:

- cis isomers: In cis isomers, two identical ligands are adjacent to each other. This arrangement can be either facial (on the same face) or meridional (on the same meridian).
- trans isomers: In trans isomers, two identical ligands are opposite to each other.

Not all octahedral complexes show geometric isomerism. The presence or absence of geometric isomerism depends on the number and type of ligands present in the complex.

Answer Explanation

Option A: [MA5B]

In this octahedral complex, there are five monodentate ligands and one vacant coordination site. As all the ligands are identical, they will occupy the same position around the metal ion. Therefore, there will be only one possible isomer, and there will be no geometric isomerism.