Using crystal field theory, draw energy level diagram, write electronic configuration of the central metal atom/ion and determine the magnetic moment value in the following
(a) [CoF6]3−,[Co(H2O)6]2+,[Co(CN)6]3−
(b) FeF3−6,[Fe(H2O)6]2+,[Fe(CN)6]4−
(a) [CoF6]3−,[Co(H2O)6]2+,[Co(CN)6]3−
[CoF6]3−
F− is a weak field ligand.
Configuration of Co3+=3d6(or t42g e2g)
Number of unpaired electrons (n)=4
Magnetic moment (μ)=√n(n+2)=√4(4+2)=√24=4.9BM [Co(H2O)6]2+
[Co(H2O)6]2+
H2O is a weak field ligand.
Configuartion of Co2+=3d7(or t52g e2g)
Number of unpaired electrons (n)=3
μ=√3(3+2)=√15=3.87BM
[Co(CN)6]3− i.e., Co3+
∵ CN is strong field ligand.
Co3+=3d6(or t62g t0g)
There is no unpaired electron, so it is diamagnetic.
μ=0
(b) FeF3−6,[Fe(H2O)6]2+,[Fe(CN)6]4−
[FeF6]3−,
Number of unpaired electrons, n=5
μ=√5(5+2) =√35=5.92BM
[Fe(H2O)6]2+
[Fe(CN)6]4−
Since, CN− is a strong field ligand, all the electrons get paired.
Fe2+=3d6(or t62ge0g)
Because there is no unpaired electron, so it is diamagnetic in nature.