Question

Which of the following is heteroleptic complex?

• A. [Co(NH$_3$)$_6$]$^{3+}$
• B. [Cr(NH$_3$)$_6$]$^{3+}$
• C. [Ni(H$_2$O)$_6$]$^{2+}$
• D. [Co(NH$_3$)$_4$Cl$_2$]$^{+}$

Hint:

Homoleptic = one type of ligand. Heteroleptic = more than one type of ligand (mixed ligands).

Answer 1

The Correct Option is D

A heteroleptic complex is a coordination compound where the central metal atom is bonded to more than one kind of ligand. This contrasts with homoleptic complexes, where the metal is surrounded by only one type of ligand.

Let's analyze the given options:

1. [Co(NH₃)₆]³⁺: This complex contains only ammonia (NH₃) as a ligand. Therefore, it is a homoleptic complex.
2. [Cr(NH₃)₆]³⁺: This complex also contains only ammonia (NH₃) as a ligand. Hence, it is a homoleptic complex.
3. [Ni(H₂O)₆]²⁺: This complex contains only water (H₂O) as a ligand. Therefore, it is a homoleptic complex.
4. [Co(NH₃)₄Cl₂]⁺: In this complex, two types of ligands are present: ammonia (NH₃) and chloride (Cl^-). This makes it a heteroleptic complex because there are different kinds of ligands attached to the cobalt (Co) metal center.

From the analysis above, the correct answer is [Co(NH₃)₄Cl₂]⁺.