JEE Main 2023 — Coordination Compounds Question with Solution

Meridional (mer) isomerism is a type of geometrical isomerism found specifically in octahedral complexes, where three identical ligands occupy a meridian plane. Thus, it requires at least three identical bidentate or monodentate ligands.

Given the options, the complex that could potentially exist as a meridional isomer is :

Option D : $[\mathrm{Co}({\mathrm{NH}}_3{)}_3({\mathrm{NO}}_2{)}_3]$

In this complex, there are three $\mathrm{N}{\mathrm{H}}_3$ and three $\mathrm{N}{\mathrm{O}}_2$ ligands, allowing it to form a meridional configuration where either all three $\mathrm{N}{\mathrm{H}}_3$ or all three $\mathrm{N}{\mathrm{O}}_2$ ligands lie along a meridian plane.