Question

Which among the following complexes is heteroleptic and cationic in nature?

• A. \([\text{Ni}(\text{CO})_4]\)
• B. \([\text{Co}(\text{NH}_3)_4\text{Cl}_2]\text{Cl}\)
• C. \([\text{Pt}(\text{NH}_3)_2\text{Cl}_2]\)
• D. \(\text{K}_4[\text{Fe}(\text{CN})_6]\)

Hint:

To identify a cationic complex, check whether counter ions (like Cl\(^-\)) are written outside the coordination sphere.

Answer 1

The Correct Option is B

Step 1: Understand the terms used.
A heteroleptic complex contains more than one type of ligand.
A cationic complex carries a positive charge on the coordination entity.
Step 2: Analyze each option.
(A) \([\text{Ni}(\text{CO})_4]\): This complex has only one type of ligand (CO) and is neutral, so it is homoleptic and not cationic.
(B) \([\text{Co}(\text{NH}_3)_4\text{Cl_2]\text{Cl}\):} This complex contains two different ligands (\(\text{NH}_3\) and \(\text{Cl}^-\)), making it heteroleptic. The coordination sphere has a \(+1\) charge, so it is cationic.
(C) \([\text{Pt}(\text{NH}_3)_2\text{Cl_2]\):} Although heteroleptic, this complex is neutral, not cationic.
(D) \(\text{K}_4[\text{Fe}(\text{CN})_6]\): This is an anionic complex, not cationic.
Step 3: Conclusion.
The complex \([\text{Co}(\text{NH}_3)_4\text{Cl}_2]\text{Cl}\) is both heteroleptic and cationic in nature.