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Question
The hexaquo manganese(II) ion contains five unpaired electrons, while the hexacyanoion contains only one unpaired electron. Explain using Crystal Field Theory.
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Solution
Mn(II) possesses a 3d5 electronic configuration. Water is a weak field ligand, resulting in a small Δ0. Therefore, the hexaaqua complex will be a high-spin complex with five unpaired electrons. On the other hand, CN− is a strong field ligand, resulting in a substantial Δ0. Therefore, in its cyano complex, the electrons are paired, resulting in a single unpaired electron.
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