Question:
Explain why [Fe(H2O)6]3+ has a magnetic moment value of 5.92 BM whereas
[Fe(CN)6]3– has a value of only 1.74 BM.
Solution:
For [Fe(H2O)6]3+, H2O is a weak field ligand won’t cause pairing of electrons. So, the number of unpaired electrons will be 5.
[Fe(CN)6]3–, Fe3+ has six unpaired electrons. CN- is a strong field ligand which will cause pairing of all the electrons. So, the electrons will start pairing leaving behind one unpaired electron.