Name: CFT: Theory of Coordination Compounds
Uploaded: 2019-07-19
Duration: 6 min 25 s
Description: There are various theories to explain bonding in coordination compounds. Crystal field theory is one of those theories. It explains many properties.

Question

The complex ${[Ni {(CN)}_{4}]}^{2 -}$ is diamagnetic, but ${[{NiCl}_{4}]}^{2 -}$ is paramagnetic and has two unpaired electrons. Explain these observations and deduce the structures of the two complexes.

Accepted Answer

$[Ni (CN)_{4}]^{2 -}$ :

Here, $Ni$ is in $+ 2$ oxidation state and ${CN}^{-}$ is strong field ligand, which will pair up the electron of ${Ni}^{2 +}$ in the complex.

The electronic configuration of ${Ni}^{2 +}$ in the complex is ${Ni}^{2 +} : [Ar] 3 d^{8} 4 s^{0} 4 p^{0}$ .

Now, $1$ orbital of $3 d$ is empty and, hence, the hybridization of ${Ni}^{2 +}$ in the complex is ${dsp}^{2}$ .

$∴$ The shape of ${[Ni {(CN)}_{4}]}^{2 -}$ is square planar. As there is an ion in the complex, it is diamagnetic.

${[{NiCl}_{4}]}^{2 -}$ :

Here, $Ni$ is in $+ 2$ oxidation state, but ${Cl}^{-}$ is a weak field ligand. Therefore, the complex will from an outer orbital or high spin complex.

The electronic configuration of ${Ni}^{2 +}$ in the complex is ${[Ni {(CN)}_{4}]}^{2 -}$ .

Here, we can see, there are $2$ unpaired electrons in the $3 d -$ orbital of ${Ni}^{2 +}$ . Therefore, the complex is paramagnetic.

The hybridization becomes ${sp}^{3}$ and, hence, the shape of ${[{NiCl}_{4}]}^{2 -}$ is tetrahedral.

The complex ${[Ni {(CN)}_{4}]}^{2 -}$ is diamagnetic, but ${[{NiCl}_{4}]}^{2 -}$ is paramagnetic and has two unpaired electrons. Explain these observations and deduce the structures of the two complexes.

Important Questions on Coordination Compounds

Learn and Prepare for any exam you want !

The complex NiCN42- is diamagnetic, but NiCl42- is paramagnetic and has two unpaired electrons. Explain these observations and deduce the structures of the two complexes.

Important Questions on Coordination Compounds

Learn and Prepare for any exam you want !

The complex ${[Ni {(CN)}_{4}]}^{2 -}$ is diamagnetic, but ${[{NiCl}_{4}]}^{2 -}$ is paramagnetic and has two unpaired electrons. Explain these observations and deduce the structures of the two complexes.