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Identify the homoleptic complex(es) that is/are low spin. (A) [Fe(CN)5NO]2− (B) [CoF6]3− (C) [Fe(CN)6]4− (D) [Co(NH3)6]3+ (E) [Cr(H2O)6]3+ Choose the correct answer from the options given below : (1) (B) and (E) only (2) (A) and (C) only (3) (C) and (D) only (4) (C) only

1. (B) and (E) only
2. (A) and (C) only
3. (C) and (D) only
4. (C) only

Correct answer: (C) and (D) only

Solution

The complexes [Fe(CN)6]4− and [Co(NH3)6]3+ are low spin due to the strong field ligands CN⁻ and NH3, which cause a significant splitting of the d-orbitals, leading to the pairing of electrons in the lower energy orbitals before occupying the higher ones.

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