Solution:
Let's analyze each complex ion to determine the correct electronic configuration based on Crystal Field Theory:
(A) [Mn(CN)6]4−
Mn in +2 oxidation state, so its electronic configuration is 3d5.
CN−is a strong field ligand, causing a large splitting of the d orbitals.
Therefore, all five electrons will occupy the lower energy t2g orbitals, leading to the configuration t2g5, which corresponds to (R).
(B) [Co(H2O)6]2+
Co in +2 oxidation state, its electronic configuration is 3d7.
H2O is a weak field ligand, resulting in a smaller splitting of the d orbitals.
Therefore, the electronic configuration will be t2g5eg2, which corresponds to (S).
(C) [Fe(H2O)6]2+
Fe in +2 oxidation state, its electronic configuration is 3d6.
H2O is a weak field ligand, leading to a smaller splitting of the d orbitals.
Therefore, the electronic configuration will be t2g4eg2, which corresponds to (Q).
(D) [MnCl4]2−
Mn in +2 oxidation state, its electronic configuration is 3d5.
Cl−is a weak field ligand. The complex is tetrahedral, which results in a different splitting pattern than octahedral complexes.
In a tetrahedral complex, the eg orbitals are lower in energy than the t2g orbitals.
Therefore, the electronic configuration will be eg2t2g3, which corresponds to (P).
Therefore, the correct matching is:
A=R
B=S
C=Q
D=P
So the final answer is Option B.
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