Question

Identify the formula of Bis(ethylenediamine)dithiocyanatoplatinum(IV)ion from following.

• A. \([\text{Pt(en)}_2(\text{NCS})]^{2+}\)
• B. \(\text{Pt}[(\text{en})_2(\text{SCN})_2]^{4+}\)
• C. \([\text{Pt(en)}_2(\text{SCN})_2]^{2+}\)
• D. \(\text{Pt}[(\text{en})_3(\text{SCN})_2]^{4+}\)

Hint:

Add the charges: Pt(IV) plus neutral en plus two SCN- gives +2.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
To write the formula from the name, put the metal first, then ligands in alphabetical order inside square brackets, and finally the overall charge.

Step 2: Decode the name:
"Bis(ethylenediamine)" means two neutral en ligands. "Dithiocyanato" means two \(\text{SCN}^-\) ligands, each with charge -1. "Platinum(IV)" means the metal has charge +4.

Step 3: Detailed Explanation:
Charge on the complex ion \(= +4 + 2(0) + 2(-1) = +2\).
The formula is \([\text{Pt(en)}_2(\text{SCN})_2]^{2+}\).

Step 4: Why the other options are wrong.
(A) has only one thiocyanate ligand, so it has the wrong ligand count. (B) and (D) write the metal outside the bracket and give a charge of 4+, which is not the net charge. Option (D) also has three en ligands instead of two.

Final Answer:
The formula is \([\text{Pt(en)}_2(\text{SCN})_2]^{2+}\), option (C). \[ \boxed{[\text{Pt(en)}_2(\text{SCN})_2]^{2+}} \]