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Question #44171

Difficulty: 8/10 | 🟢 Free

The Question

The hexaaquacopper(II) complex ion, $\ce{[Cu(H2O)6]^{2+}}$ , exists in aqueous solution at 298 K. Due to its electronic configuration, it undergoes a spontaneous geometric distortion. Identify the correct point group symmetry of the distorted complex and the specific d-orbital that houses the unpaired electron.

Options

A.
$D_{4h}$ , $d_{x^2-y^2}$
B.
$D_{4h}$ , $d_{z^2}$
C.
$O_h$ , $e_g$
D.
$D_{3d}$ , $d_{xy}$

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Correct Answer

Step-by-Step Solution

Explanation

How the Examiner Thinks

Exception_Exposure

Learn to identify edge cases and boundary exceptions that JEE examiners hide in math problems.

Concepts Behind This Question

Hybridization in Non-Standard Cases|Crystal Field Splitting (Octahedral)|d-block Variable Oxidation States

Why This Question Is Tricky

Common Mistakes

The question tests the application of the Jahn-Teller theorem, challenging the high school dogma of fixed $sp^3d^2$ hybridization for coordination number 6.

Students often overlook that a $d^9$ electronic configuration results in an asymmetrically filled $e_g$ set, causing a spontaneous symmetry-breaking distortion (Z-out elongation) to lower the system's energy.

A common trap is assuming perfect $O_h$ symmetry or confusing the energy ordering of the split $e_g$ orbitals, incorrectly placing the unpaired electron in the stabilized $d_{z^2}$ orbital instead of the destabilized $d_{x^2-y^2}$ orbital.

Quick Facts About This Question

Question Information

Subject	Chemistry
Chapter	Chemical Bonding and Molecular Structure - Class 11 Part 1
Concept	Hybridization in Non-Standard Cases
Difficulty	8
Cognitive Load	7
Target Solve Time	160 sec
Access	Free