Question

The correct structure of the complex having IUPAC name sodium hexanitrocobaltate(III) is:

• A. \( Na_3 [Co(NO_2)_5] \)
• B. \( Na_4 [Co(NO_2)_6] \)
• C. \( Na_3 [Co(NO_2)_6] \)
• D. \( Na_4 [Co(NO_2)_5] \)

Hint:

For complex salts, the number of counterions must balance the charge of the coordination complex.

Answer 1

The Correct Option is C

The given IUPAC name is sodium hexanitrocobaltate(III). 
- "Hexanitro-" refers to six \( NO_2 \) ligands.
- "Cobaltate" indicates the presence of a complex anion.
- The oxidation state of cobalt is (III), meaning \( Co^{3+} \).
- The charge of \( [Co(NO_2)_6]^{3-} \) requires three \( Na^+ \) ions for charge neutrality.
Thus, the correct formula is \( Na_3 [Co(NO_2)_6] \), making the correct answer (c).