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Question #44576

Difficulty: 8/10 | 🟢 Free

The Question

An aqueous solution of a coordination compound with the empirical formula \ce{M(en)2Cl3} (where \ce{M^{3+}} is a d6d^6 transition metal) is treated with excess \ce{AgNO3(aq)} at 298 K298\text{ K}, yielding exactly 1 mol1\text{ mol} of \ce{AgCl(s)} precipitate per mole of the compound. The complex cation exists in multiple stereoisomeric forms. Due to the anisotropic ligand field, the crystal field splitting energy (Δo\Delta_o) is highly sensitive to the geometry. In the \textit{trans}-isomer, the weaker axial field results in Δo<P\Delta_o < P (where PP is the spin-pairing energy). Conversely, in the \textit{cis}-isomer, the synergistic ligand field yields Δo>P\Delta_o > P.

Calculate the sum of the numerical values of: (i) The total number of stereoisomers of the complex cation. (ii) The number of unpaired electrons in the high-spin isomer. (iii) The spin-only magnetic moment (in BM) of the optically active isomer(s).

Options

  • A.

    7

  • B.

    6

  • C.

    11.90

  • D.

    5

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

Optical Isomerism Logic|Valence Bond Theory Hybridization|Spin-Only Magnetic Moment

Why This Question Is Tricky

Common Mistakes

Tests the intersection of Crystal Field Theory and Stereochemistry.

Students typically rely on the heuristic that d6d^6 complexes with strong-field ligands (like ethylenediamine) are universally low-spin (d2sp3d^2sp^3, diamagnetic).

The trap introduces a geometry-dependent ligand field where the trans-isomer is forced into a high-spin state (Δo<P\Delta_o < P) while the cis-isomer remains low-spin (Δo>P\Delta_o > P).

To solve, the student must decouple the magnetic moment calculation from the empirical formula and correctly map the high/low spin states to the specific chiral (cis) and achiral (trans) geometries.

Quick Facts About This Question

Question Information

SubjectChemistry
ChapterCoordination Compounds - Class 12
ConceptOptical Isomerism Logic
Difficulty8
Cognitive Load7
Target Solve Time160 sec
AccessFree