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

Concept: Coordination complexes are classified as:

• 
  Homoleptic complexes: Contain only one type of ligand.
• 
  Heteroleptic complexes: Contain more than one type of ligand.

Step 1: Check each option.
Option (A): [Co(NH$_3$)$_6$]$^{3+}$ Contains only NH$_3$ ligands → Homoleptic.
Option (B): [Cr(NH$_3$)$_6$]$^{3+}$ Only NH$_3$ ligands → Homoleptic.
Option (C): [Ni(H$_2$O)$_6$]$^{2+}$ Only H$_2$O ligands → Homoleptic.
Option (D): [Co(NH$_3$)$_4$Cl$_2$]$^{+}$ Contains two different ligands: NH$_3$ and Cl$^-$. Hence, heteroleptic complex.