Question

The octahedral complex ion $ {{[FeC{{l}_{6}}]}^{3-}} $

• A. 5 unpaired electrons $ (t_{2g}^{3}e_{g}^{2}) $
• B. 1 unpaired electron $ (t_{2g}^{1}) $
• C. 3 unpaired electrons $ (t_{2g}^{1}e_{g}^{2}) $
• D. All the electrons are paired

Answer 1

Answer: (A)

In $ {{[FeC{{l}_{6}}]}^{3-}},Fe $ is in + 3 oxidation state. Cl is a weak field ligand so the electrons remain unpaired. $ _{26}Fe=[Ar]3{{d}^{6}}4{{s}^{2}};F{{e}^{3+}}=[Ar]3{{d}^{5}} $ ( $ 5{{e}^{-}}, $ unpaired electrons) Therefore, option $ (a)t_{2g}^{3}e_{g}^{2} $ is correct.