Question

Find oxidation number and coordination number of Fe in K\(_4\)[Fe(CN)\(_6\)].

Hint:

Oxidation number is found by charge balance; coordination number = number of ligands directly bonded.

Answer 1

Step 1: Formula.
The complex is K\(_4\)[Fe(CN)\(_6\)]. Potassium has charge +1. Cyanide ion (CN\(^-\)) has charge –1.
Step 2: Calculation of oxidation state.
Let oxidation state of Fe = \(x\). \[ 4(+1) + x + 6(-1) = 0 \] \[ 4 + x - 6 = 0 \implies x - 2 = 0 \implies x = +2 \] Step 3: Coordination number.
The number of ligands directly attached to Fe is 6 (from 6 CN\(^-\) ligands). Hence, coordination number = 6.
Step 4: Conclusion.
Oxidation number of Fe = +2, coordination number = 6.