Which of the following is diamagnetic?
- $[Fe(CN)_6]^{3-}$
\(Co(O_x)_3]^{3-}\)
- $[FeF_6]^{3-}$
- $[CoF_6]^{3-}$
The Correct Option is B
Solution and Explanation
\([Fe(CN)_6]^{3-}\) has magnetic moment of a single unpaired electron whereas \([FeF_6]^{3-}\) has a magnetic moment of five unpaired electrons.
\([CoF_6]^{3-}\) is paramagnetic with four unpaired electrons while \([Co(C_2O_4)_3]^3\) is diamagnetic. This anomaly is explained by valence bond theory in terms of formation of inner and outer orbital coordination entities. \([Co(C_2O_4)_3]^{3-}\) is an inner orbital complexes having \(d^2sp^3\) hybridization.
So, the correct option is (B): \(Co(O_x)_3]^{3-}\)
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Concepts Used:
Coordination Compounds
A coordination compound holds a central metal atom or ion surrounded by various oppositely charged ions or neutral molecules. These molecules or ions are re-bonded to the metal atom or ion by a coordinate bond.
Coordination entity:
A coordination entity composes of a central metal atom or ion bonded to a fixed number of ions or molecules.
Ligands:
A molecule, ion, or group which is bonded to the metal atom or ion in a complex or coordination compound by a coordinate bond is commonly called a ligand. It may be either neutral, positively, or negatively charged.