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Question
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:
\[\ce{[FeF6]^{3-}, [Fe(H2O)6]^{2+}, [Fe(CN)6]^{4-}}\]
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Solution
(1) \[\ce{FeF^{3-}6}\]:
\[\ce{Fe^{3+} = 3d^5}\]
Number of unpaired electrons = 5
Magnetic moment = `sqrt(5(5 + 2))` = 5.92 BM
(2) \[\ce{[Fe(H2O)6]^{2+}}\]:
\[\ce{Fe^{2+} = 3d^6}\]
Number of unpaired electrons = 4
Magnetic moment = `sqrt(4(4 + 2))` = 4.9 BM
(3) \[\ce{[Fe(CN)6]^{4-}}\]:
\[\ce{Fe^{2+} = 3d^6}\]
Since CN– is a strong field ligand all the electrons get paired.
No unpaired electrons so diamagnetic.
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