Question

Explain the magnetic behaviour of the complex K₃[Fe(CN)₆] on the basis of valence bond theory.

Answer 1

1. The magnetic behavior of the complex K₃[Fe(CN)₆] can be explained based on the strong field nature of the cyanide (CN⁻) ligands. Fe³⁺, which has the electron configuration 3d⁵, undergoes d²sp³ hybridization to form six bonds with the six cyanide ligands in an octahedral arrangement.
2. Because the cyanide ions cause a significant separation of the d-orbitals, the five electrons in the Fe³⁺ ion pair up in the lower-energy t_2g orbitals.
3. As a result, there are no unpaired electrons in the complex. Since magnetic properties are directly related to the presence of unpaired electrons, the absence of unpaired electrons makes K₃[Fe(CN)₆] diamagnetic.
4. This means the complex does not exhibit any magnetic moment and is not attracted to a magnetic field.