Question

Discuss the nature of bonding in $\left[Fe\right(CN{)}_6{]}^{-4}$ on the basis of valence bond theory. What is its structure and magnetic characteristics?

(At number $Fe=26$)

Answer 1

In the above coordination complex, iron exists in the $+2$ oxidation state.

$F{e}^{2+}$: Electronic configuration is $3d^6$.

Orbitals of $F{e}^{2+}$ ion:

As $C{N}^{-}$ is a strong ligand, it causes the pairing of the unpaired $3d$ electrons.

since there are six ligands around the central metal ion, the most feasible hybridization is $d^{2}s{p}^3$.

$d^{2}s{p}^3$ hybridized orbitals of $F{e}^{2+}$ are $6$ electron pairs are from $C{N}^{-}$ ion occupy the six hybrid $d^{2}s{p}^3$ orbitals.

Hence, the geometry of the complex is octahedral and the complex is diamagnetic (as there are no unpaired electrons).