Question

Identify anionic complex from following

• A. Bis (ethylene diamine) dithiocyanatoplatinum (IV)
• B. Pentaamminecarbonatocobalt (III) chloride
• C. Pentacarbonyliron (0)
• D. Sodiumhexanitrocobaltate (III)

Answer 1

The Correct Option is D

Correct Answer: (4) Sodium hexanitrocobaltate(III)

Solution:

To determine the anionic complex, we classify coordination compounds based on the net charge of the complex ion:

• Cationic complex: Positively charged complex ion
• Neutral complex: No net charge
• Anionic complex: Negatively charged complex ion

Let’s evaluate each option:

(1) Bis(ethylenediamine)dithiocyanatoplatinum(IV)
- Ethylenediamine is neutral, dithiocyanate is anionic
- Platinum is +4; overall charge is balanced
→ Neutral complex → Not anionic

(2) Pentaamminecarbonatocobalt(III) chloride
- Ammine is neutral, carbonate is -2
- Cobalt is +3, and there's an external Cl⁻ ion
→ Complex is cationic → Not anionic

(3) Pentacarbonyliron(0)
- CO is a neutral ligand
- Iron is in 0 oxidation state
→ Neutral complex → Not anionic

(4) Sodium hexanitrocobaltate(III)
- Sodium (Na⁺) is outside the complex
- Complex: [Co(NO₂)₆]³⁻
→ Negatively charged complex ion → This is the anionic complex