JEE Main 2025 Jan 29 Shift 2, Chemistry Q12: Introduction And Nomenclature

JEE Main2025Jan 29, Shift 2Chemistry

Identify the homoleptic complexes with odd number of d electrons in the central metal.

(A) $[F e O_{4}]^{2 -}$

(B) $[F e (C N)_{6}]^{3 -}$

(D) $[C o C l_{4}]^{2 -}$

(E) $[C o (H_{2} O)_{3} F_{3}]$

Choose the correct answer from the options given below :

Solution

A homoleptic complex contains only one type of ligand. Check each species for (i) ligand uniformity and (ii) parity of the $d$ electron count.

(A) $[F e O_{4}]^{2 -}$ : Homoleptic with $O^{2 -}$ , but $F e$ is in $+ 6$ state, $d^{2}$ . Even count, rejected.

(B) $[F e (C N)_{6}]^{3 -}$ : Homoleptic with $C N^{-}$ ; $F e^{3 +}$ has $d^{5}$ . Odd, accepted.

(C) $[F e (C N)_{5} N O]^{2 -}$ : Mixed ligands $(C N^{-}, N O^{+})$ , not homoleptic.

(D) $[C o C l_{4}]^{2 -}$ : Homoleptic with $C l^{-}$ ; $C o^{2 +}$ has $d^{7}$ . Odd, accepted.

(E) $[C o (H_{2} O)_{3} F_{3}]$ : Mixed ligands $(H_{2} O, F^{-})$ , not homoleptic.

$∴$ Only (B) and (D) satisfy both conditions.

Concept behind this question

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