Question

Justify with reasons:
[Fe(H\(_2\)O)\(_6\)]\(^{3+}\) is stronger paramagnetic while [Fe(CN)\(_6\)]\(^{3-}\) is weaker paramagnetic.

Hint:

The strength of the ligand affects the \(d\)-orbital splitting and determines the magnetic properties of the complex.

Answer 1

The difference in the magnetic properties of \([Fe(H_2O)_6]^{3+}\) and \([Fe(CN)_6]^{3-}\) can be attributed to the ligands involved. Water is a weak field ligand that causes minimal splitting of the \(d\)-orbitals in \([Fe(H_2O)_6]^{3+}\). As a result, unpaired electrons remain in the \(d\)-orbitals, making the complex strongly paramagnetic. Cyanide, however, is a strong field ligand, which causes a large splitting of the \(d\)-orbitals in \([Fe(CN)_6]^{3-}\), leading to the pairing of electrons and reducing the paramagnetism of the complex.