Question

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

• A. 6
• B. 5
• C. 4
• D. 2

Hint:

Secondary valency is the coordination number of the central metal, that is, the total number of ligand donor atoms directly bonded to the metal.

Answer 1

The Correct Option is A

Step 1: Define secondary valency.
The secondary valency is the coordination number, that is, the total number of donor atoms directly bonded to the central metal.

Step 2: Look at the ligands.
The complex is \([Pt(en)_2Cl_2]^{2+}\). It has two 'en' ligands and two \(Cl^-\) ligands.

Step 3: Count donor atoms from en.
'en' (ethylenediamine) is bidentate, so each en gives \(2\) donor atoms. Two en give \(2 \times 2 = 4\) donor atoms.

Step 4: Add the chloride donors.
The two \(Cl^-\) give \(2\) more donor atoms. Total \(= 4 + 2 = 6\).

Step 5: Conclusion.
The coordination number, that is the secondary valency, is \(6\).

\[ \boxed{6} \]