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Question #44559

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The Question

A coordination compound has the empirical formula \ce{CoFeC6H18N12}. It exhibits coordination isomerism, existing as two primary isomers, $C_1$ and $C_2$ . In both isomers, the metals are in the +3 oxidation state and form homoleptic octahedral entities.

In $C_1$ , the complex cation contains the metal with the higher atomic number. In $C_2$ , the complex cation contains the metal with the lower atomic number.

Let $E^\circ_1$ and $E^\circ_2$ be the standard reduction potentials for the \ce{Co(III)/Co(II)} redox couple in the respective coordination environments of $C_1$ and $C_2$ at 298 K.

Which of the following correctly gives the IUPAC name of $C_2$ and the correct thermodynamic relationship between $E^\circ_1$ and $E^\circ_2$ ?

Options

A.
Hexaammineiron(III) hexacyanidocobaltate(III) ; $E^\circ_1 > E^\circ_2$
B.
Hexaammineiron(III) hexacyanidocobaltate(III) ; $E^\circ_1 < E^\circ_2$
C.
Hexaamminecobalt(III) hexacyanidoferrate(III) ; $E^\circ_1 > E^\circ_2$
D.
Hexaamminecobalt(III) hexacyanidoferrate(III) ; $E^\circ_1 < E^\circ_2$

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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

Coordination Isomerism|IUPAC Nomenclature Priority|Electrode Potential Dependencies

Why This Question Is Tricky

Common Mistakes

This question tests the intersection of coordination isomerism, IUPAC nomenclature, and the thermodynamic consequences of Crystal Field Theory.

Students often memorize that Co(III) is a strong oxidizing agent but fail to account for the 'Hidden Variable': the nature of the ligand field.

A strong field ligand like \ce{CN^-} creates a massive \Delta_o, exceptionally stabilizing the $t_{2g}^6$ state of Co(III) and drastically lowering its reduction potential compared to the ammine complex.

The trap lies in confusing the isomers based on atomic numbers or assuming that a stronger ligand field makes the complex a stronger oxidizing agent.

Quick Facts About This Question

Question Information

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