Q. 46 Using crystal field theory, draw energy level diagram, wrile electronic

configuration of the central metal atom/ion and determine the magnetic

moment value in the following.

(a)  CoF63-,Co(H20)62+,Co(CN)63-

(b) FeF63-Fe(H20)62+,Fe(CN)64-


F is a weak field ligand.

Configuration of Co3+=3d6(ort2g4eg2

Number of unpaired electrons (n) =4

Magnetic moment (μ)=n(n+2)=4(4+2)=24=4.9BMCo(H2O62+

 H2O is a weak field ligand.

Configuration of Co2+=3d7(or t2g5eg2)Number of unpaired electons (n) =3μ=3(3+2) =15=3.87 BMCo(CN)63- e.e., Co3+ CN is strong field ligand.

There is no unpaired electon, so it is diamagnetic


(b) FeF63-

Fe3+=3d5(or t2g3e2g)Number of unpaireed electons, n=5μ=5(5+2)=35=5.92BMFe(H2O62+

Fe3+=3d5(or t2g3e2g)Number of unpaireed electons, n=4μ=4(4+2)=24=Fe(CN)64-

Since , CN is a strong filed ligand, all the electrons get paired.

Fe2+=3d6(or t2g6e20)

Because there is no unpaired electron, so it is diamagnetic in nature.