JEE Main 2024 — Coordination Compounds Question with Solution

A homoleptic complex is one in which a central metal atom or ion is surrounded by only one kind of donor groups, ligands or ions. On the other hand, a heteroleptic complex contains a central metal surrounded by more than one kind of donor groups, ligands or ions.

Let's examine the given options :

Option A: $\left[\mathrm{Ni}{\left({\mathrm{NH}}_3\right)}_2{\mathrm{Cl}}_2\right]$

This complex contains two different ligands, ammonia (${\mathrm{NH}}_3$) and chloride (Cl). Therefore, it is a heteroleptic complex.

Option B: ${\left[\mathrm{Co}{\left({\mathrm{NH}}_3\right)}_4{\mathrm{Cl}}_2\right]}^{+}$

Just like Option A, this complex has two types of ligands, ammonia (${\mathrm{NH}}_3$) and chloride (Cl), making it a heteroleptic complex.

Option C: ${\left[\mathrm{Fe}{\left({\mathrm{NH}}_3\right)}_4{\mathrm{Cl}}_2\right]}^{+}$

Again, this complex has ammonia (${\mathrm{NH}}_3$) and chloride (Cl) ligands, so it is a heteroleptic complex.

Option D: ${\left[\mathrm{Ni}(\mathrm{CN}{)}_4\right]}^{2-}$

This complex has only cyanide (CN) ligands surrounding the nickel ion, with no other types of ligands present. Thus, this is a homoleptic complex because it is coordinated by a single type of ligand.

Therefore, Option D is the correct answer as it represents a homoleptic complex.