Explain why `[Fe(H_(2)O)_(6)]^(3+)` has magnetic moment value of 5.92 BM whereas `[Fe(CN)_(6)]^(3-)` has a value of only 1.74 BM.

Explanation

`[Fe(CN)_(6)]^(3-)` involves `d^(2)sp^(3)` hybridisation with one unpaired electron and `[Fe(H_(2)O)_(6)]^(3+)` involves `sp^(3)d^(2)` hybridisation with five unpaired electrons. This difference is due to the presence of strong ligand `CN^(-)` and weak ligand `H_(2)O` in these complexes.