Question

Justify with reasons:
[NiCl\(_4\)]\(^{2-}\) is paramagnetic while [Ni(CO)\(_4\)] is diamagnetic, although both are tetrahedral.

Hint:

The type of ligand determines the extent of \(d\)-orbital splitting and influences the magnetic properties of the complex.

Answer 1

The magnetic properties of \([NiCl_4]^{2-}\) and \([Ni(CO)_4]\) differ due to the nature of the ligands. In \([NiCl_4]^{2-}\), chloride ions are weak field ligands, which cause minimal splitting of the \(d\)-orbitals. This results in unpaired electrons, making the complex paramagnetic. On the other hand, carbon monoxide is a strong field ligand, which causes a significant splitting of the \(d\)-orbitals, leading to the pairing of electrons in \([Ni(CO)_4]\). This electron pairing makes the complex diamagnetic, despite both complexes having a tetrahedral geometry.