For the octahedral complexes of Fe3+ in SCN– (thiocyanato - S) and in CN– ligand environments, the difference between the spin only magnetic moments in Bohr magnetons (when approximated to the nearest integer) is: [Atomic number of Fe = 26]

Engineering

Chemistry

Crystal Field Theory and Valence Bond Theory

Question

For the octahedral complexes of Fe³⁺ in SCN^– (thiocyanato - S) and in CN^– ligand environments, the difference between the spin only magnetic moments in Bohr magnetons (when approximated to the nearest integer) is:

[Atomic number of Fe = 26]

LiveFree JEE Main Previous Year Online Papers Live Free JEE Advance Previous Year Online Papers

College PredictorLive

Know your College Admission Chances Based on your Rank/Percentile, Category and Home State.

Get your JEE Main Personalised Report with Top Predicted Colleges in JoSA

[Fe(SCN)₆]^3- and [Fe(CN)₆]^3-

In both the cases the electronic configuration of Fe³⁺ will be

1s², 2s², 2p⁶, 3s², 3p⁶, 3d⁵

Since SCN is a weak field ligand and $\bar{C} N$ is a strong field ligand, the pairing will occur only in case of [Fe(CN)₆]^3-

Difference in spin only magnetic moment = 5.91 – 1.73 = 4.18 ≈ 4