JEE Main 2022 · 29 Jul · Shift 2 · Chemistry Q71

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ChemistrySingle correct+4 / -1Question 71 of 90

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 $_2$ )

\mathrm{[Cu(H_2O)_6]SO_4}

\mathrm{[Cu(en)(H_2O)_4]SO_4}

cis-

\mathrm{[Cu(en)_2Cl_2]}

trans-

\mathrm{[Cu(en)_2Cl_2]}

Answer and worked solution

Official answer: A

Jahn-Teller. With six identical weak-field water ligands, the $d^9$ $e_g$ degeneracy is fully expressed, giving the largest tetragonal elongation. Mixed and chelating ligands already break the symmetry and constrain the distortion.

(A)

Topics:Crystal field theory

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JEE Main 2022 · 29 Jul · Shift 2, Chemistry question 71