Question

The secondary valency of Pt in \( [Pt(en)_2Cl_2]^{2+ \) is}

• A. 6
• B. 5
• C. 4
• D. 2

Hint:

Ethylenediamine (en) is a very common bidentate ligand. Always multiply its count by 2 when calculating the coordination number.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
In coordination chemistry, the secondary valency of a metal atom refers to its coordination number, which is the total number of ligand donor atoms directly bonded to it.
Step 2: Detailed Explanation:
In the complex \( [Pt(en)_2Cl_2]^{2+} \):
1. 'en' (ethylenediamine) is a bidentate ligand. There are 2 'en' molecules.
Contribution to C.N. = \( 2 \times 2 = 4 \).
2. 'Cl' (chloride) is a monodentate ligand. There are 2 chloride ions.
Contribution to C.N. = \( 2 \times 1 = 2 \).
Total C.N. = \( 4 + 2 = 6 \).
Therefore, the secondary valency is 6.
Step 3: Final Answer:
The secondary valency of Pt in the given complex is 6.