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Question #44579

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The Question

Consider the following three mononuclear coordination complexes: (I) \ce{[Pt(gly)2]} (II) \ce{[Zn(gly)2]} (III) \ce{[Co(en)2Cl2]+} (where gly = glycinato, en = ethylenediamine)

Assume all complexes exhibit their ideal, characteristic coordination geometries without any solvent coordination. Let $S$ represent the total number of stereoisomers and $E$ represent the number of enantiomeric pairs for a given complex. Which of the following options correctly lists the values of $(S, E)$ for complexes (I), (II), and (III) respectively?

Options

A.
(I): (2, 0); (II): (2, 1); (III): (3, 1)
B.
(I): (2, 0); (II): (1, 0); (III): (3, 1)
C.
(I): (3, 1); (II): (2, 1); (III): (4, 1)
D.
(I): (2, 0); (II): (2, 0); (III): (3, 1)

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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

Optical Isomerism Logic|Geometric Isomerism Requirements|Oxidation State Traps

Why This Question Is Tricky

Common Mistakes

This question tests the student's ability to move beyond rote memorization of optical isomerism rules.

The primary trap lies in Complex (II), \ce{[Zn(gly)2]}.

Students often falsely assume that tetrahedral complexes are only chiral if all four ligands are different, or they memorize that bis-chelate complexes are only chiral in octahedral \textit{cis} geometries.

By forcing them to evaluate the symmetry of a tetrahedral $[M(AB)_2]$ complex, the question reveals that the unsymmetrical bidentate ligand breaks the $S_4$ improper axis of rotation present in $[M(AA)_2]$ , rendering the molecule chiral ( $C_2$ symmetry).

Additionally, it tests the fundamental assignment of coordination geometries based on periodic trends ( $5d^8$ vs $3d^{10}$ ).

Quick Facts About This Question

Question Information

Subject	Chemistry
Chapter	Coordination Compounds - Class 12
Concept	Optical Isomerism Logic
Difficulty	8
Cognitive Load	7
Target Solve Time	160 sec
Access	Free