Question

Identify homoleptic complex from following :

• A. $[\text{Co}(\text{NH}_3)_6]\text{Cl}_3$
• B. $[\text{Co}(\text{NH}_3)_4\text{Cl}_2]$
• C. $[\text{Co}(\text{NH}_3)_5\text{Cl}]\text{SO}_4$
• D. $[\text{Co}(\text{ONO})(\text{NH}_3)_5\text{Cl}_2]$

Hint:

Look strictly inside the square brackets $[\quad]$. If you see more than one chemical species attached to the central metal, it's immediately heteroleptic. Ignore counter-ions outside the brackets!

Answer 1

The Correct Option is A

Step 1: Understanding the Question:
We need to identify which of the provided coordination compounds qualifies as a "homoleptic" complex.

Step 2: Key Formula or Approach:
A

homoleptic complex is a coordination compound in which the central metal atom or ion is bound to only one specific kind of donor group (ligand).
A

heteroleptic complex is one where the central metal atom is bound to more than one distinct type of ligand.

Step 3: Detailed Explanation:
Let's analyze the coordination sphere (the square brackets) of each option:
(A) $[\text{Co}(\text{NH}_3)_6]^{3+}$: The central Cobalt ion is bound to six identical ammine ($\text{NH}_3$) ligands. Because there is only one type of ligand, it is homoleptic.
(B) $[\text{Co}(\text{NH}_3)_4\text{Cl}_2]$: The Cobalt ion is bound to four ammine ligands and two chloride ligands. Since there are two different types, it is heteroleptic.
(C) $[\text{Co}(\text{NH}_3)_5\text{Cl}]^{2+}$: The Cobalt ion is bound to five ammine ligands and one chloride ligand. It is heteroleptic.
(D) $[\text{Co}(\text{ONO})(\text{NH}_3)_5\text{Cl}_2]$: This coordination sphere contains nitrite, ammine, and chloride ligands. It is highly heteroleptic.

Step 4: Final Answer:
The only homoleptic complex is $[\text{Co}(\text{NH}_3)_6]\text{Cl}_3$, matching option (A).