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Question #45079

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The Question

Consider the octahedral coordination complex $\ce{[Co(en)_2(L)]SO_4}$ , where 'en' is ethane-1,2-diamine and 'L' is a bidentate ligand derived from the mono-deprotonation of glutamic acid ( $\ce{HOOC-CH_2-CH_2-CH(NH_2)-COOH}$ ). The ligand 'L' coordinates to the cobalt center exclusively through its $\alpha$ -amino and $\alpha$ -carboxylate groups, leaving the side-chain carboxylic acid uncoordinated. Ignoring stereodescriptors, determine the correct systematic IUPAC name of this coordination complex.

Options

A.
(2-amino-4-carboxybutanoato)bis(ethane-1,2-diamine)cobalt(III) sulfate
B.
(4-amino-4-carboxylatobutanoic acid)bis(ethane-1,2-diamine)cobalt(III) sulfate
C.
(2-aminopentanedioato)bis(ethane-1,2-diamine)cobalt(IV) sulfate
D.
(4-amino-4-carboxybutanoato)bis(ethane-1,2-diamine)cobalt(III) sulfate

Check Your Answer

Correct Answer

Step-by-Step Solution

Explanation

How the Examiner Thinks

Mechanism_Trap

Don't get tricked by the process! Learn the mechanical traps used in competitive exam questions.

Concepts Behind This Question

IUPAC Nomenclature Priority|Complex Ion Oxidation States|Ligand Denticity Variations

Why This Question Is Tricky

Common Mistakes

The question tests a critical intersection between Organic and Coordination IUPAC nomenclature.

In pure organic chemistry, a neutral carboxylic acid ( $\ce{-COOH}$ ) has higher priority than a carboxylate anion ( $\ce{-COO^-}$ ).

However, when naming an anionic ligand for a coordination complex, the coordinated anionic group MUST be designated as the principal functional group (taking the suffix '-oato').

The uncoordinated neutral group is relegated to a substituent (prefix 'carboxy').

Students who blindly apply organic priority rules will incorrectly assign $\ce{-COOH}$ as C1, leading to the trap name '4-amino-4-carboxylatobutanoic acid'.

Furthermore, the problem tests the ability to deduce the correct oxidation state (+3) by recognizing the ligand as a monoanion, trapping students who assume glutamic acid coordinates as a dianion (+4 oxidation state).

Quick Facts About This Question

Question Information

Subject	Chemistry
Chapter	Organic Chemistry – Some Basic Principles and Techniques - Class 11 Part 2
Concept	IUPAC Nomenclature Priority
Difficulty	8
Cognitive Load	7
Target Solve Time	160 sec
Access	Free