Question

Give reason :
$\left[Fe\right(H_{2}O{)}_6{]}^{3+}$ is strongly para magnetic whereas $\left[Fe\right(CN{)}_6{]}^{3-}$ is weakly para magnetic

Answer 1

This is due to the fact that $H_{2}O$ is a weak field ligand that forms high spin complexes. In $\left[Fe\right(H_{2}O)6{]}^{3+}$ there are 5 unpaired electrons whereas in $\left[Fe\right(CN{)}_6{]}^{3-}$ there is only one unpaired electron.

This is the reason why $\left[Fe\right(H_{2}O{)}_6{]}^{3+}$ is strongly paramagnetic whereas$\left[Fe\right(CN{)}_6{]}^{3-}$ is weakly paramagnetic.