JEE Main · 2022 · 29 Jul 2022 · Shift 2 · Coordination Compounds

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Octahedral complexes of copper (II) undergo structural distortion (Jahn-Teller). Which one of the given copper (II) complexes will show the maximum structural distortion?
(en-ethylenediamine;

H_{2} N - CH_{2} - CH_{2} - NH_{2}

)

(A) $[Cu (H_{2} O)_{6}] SO_{4}$ ✓ Correct
(B) $[Cu (en) (H_{2} O)_{4}] SO_{4}$
(C)cis- $[Cu (en)_{2} Cl_{2}]$
(D)trans- $[Cu (en)_{2} Cl_{2}]$

Answer: (A)

Solution

Jahn-Teller distortion in

Cu^{2 +}

complexes (d⁹ configuration) arises from asymmetric filling of the

e_{g}

orbitals. The distortion is maximum when all ligands are identical and weak-field, allowing maximum flexibility for elongation or compression.

[Cu (H_{2} O)_{6}]^{2 +}

has six identical weak-field ligands (water), leading to maximum Jahn-Teller distortion. The other complexes have mixed ligands (en, Cl) which constrain the geometry.

Answer: (A)

[Cu (H_{2} O)_{6}] SO_{4}

JEE Main · 2022 · 29 Jul 2022 · Shift 2 · Single correct option

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JEE Main · 2022 · 29 Jul 2022 · Shift 2 · Coordination Compounds

Solution

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