Question

Oxidation state of Fe in the complex \( K_3[Fe(CN)_5NO] \) is (+) ........... 
 

Hint:

In coordination compounds, the oxidation state of the metal is calculated by balancing the charges of the ligands and the overall charge of the complex.

Answer 1

Correct Answer: 2

Step 1: Identify the overall charge

The complex contains 3 K⁺ ions, so the complex ion [Fe(CN)₅NO]³⁻ has a charge of -3.

Step 2: Assign oxidation states

Using the standard approach for nitrosyl complexes:

$$\text{Oxidation state of Fe} + \text{Charge from ligands} = -3$$

Step 3: Determine ligand charges

• CN⁻: 5 cyanide ligands contribute 5 × (-1) = -5
• NO: In coordination complexes like this (analogous to sodium nitroprusside), NO is treated as NO⁺, contributing +1

Step 4: Calculate Fe oxidation state

$$x + 5(-1) + (+1) = -3$$ $$x - 5 + 1 = -3$$ $$x - 4 = -3$$ $$x = +2$$

Answer: +2