Question

Which is more likely to be paramagnetic, $\mathbf{\text{Fe}}{{\mathbf{\left(}\mathbf{\text{CN}}\mathbf{\right)}}_{\mathbf{\text{6}}}}^{\mathbf{\text{4-}}}$ or $\mathbf{\text{Fe}}{{\mathbf{\left(}{\mathbf{\text{H}}}_{\mathbf{\text{2}}}\mathbf{\text{O}}\mathbf{\right)}}_{\mathbf{\text{6}}}}^{\mathbf{\text{2+}}}$? Explain.

Short answer

Here, $\text{Fe}{{\left({\text{H}}_{\text{2}}\text{O}\right)}_{\text{6}}}^{\text{2+}}$is more likely to be paramagnetic.

Step-by-step solution

A concept:

Paramagnetism is a form of magnetism where some materials are weakly attracted by an externally applied magnetic field and create internal, induced magnetic fields in the direction of the applied magnetic field.

Explain which are more likely to be paramagnetic:

As ${\text{CN}}^{-}$is a strong field ligand and ${\text{H}}_{\text{2}}\text{O}$is a weak field ligand.

A strong field ligand causes pairing of electrons due to large crystal field splitting energy hence pairing of electrons occurs whereas a weak field ligand fails to do so.