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ChemHardMain 2026 • 2nd Apr - Shift 1

Match Chromium III Complexes with Crystal Field Splitting Energy Values

Match List - I with List - II.

List - IList - IIChromium (III) ComplexesΔ0(cm−1)(en=ethylene diamine)A. [Cr(CN)6]3−I. 15,060B. [CrF6]3−II. 17,400C. [Cr(H2O)6]3+III. 22,300D. [Cr(en)3]3+IV. 26,600\begin{array}{|l|l|}\hline \text{List - I} & \text{List - II} \\ \text{Chromium (III) Complexes} & \Delta_0 (\text{cm}^{-1}) \\ (en = \text{ethylene diamine}) & \\ \hline \text{A. } [\text{Cr}(\text{CN})_6]^{3-} & \text{I. } 15,060 \\ \text{B. } [\text{CrF}_6]^{3-} & \text{II. } 17,400 \\ \text{C. } [\text{Cr}(\text{H}_2\text{O})_6]^{3+} & \text{III. } 22,300 \\ \text{D. } [\text{Cr}(en)_3]^{3+} & \text{IV. } 26,600 \\ \hline \end{array}

Choose the correct answer from the options given below :

Options

A

A-I, B-II, C-III, D-IV

B

A-II, B-III, C-IV, D-I

C

A-III, B-IV, C-I, D-II

D

A-IV, B-I, C-II, D-III

Correct

Topics & Concepts

Coordination CompoundsCoordination CompoundsCrystal Field Theory

Step-by-Step Solution

To determine the correct matching between the Chromium (III) complexes in List - I and their crystal field splitting energy (Δ0\Delta_0) values in List - II, we use Crystal Field Theory (CFT).

  1. Oxidation State of Central Metal: In all four given complexes, the central metal ion is Chromium in the +3+3 oxidation state (Cr3+\text{Cr}^{3+}, 3d33d^3 configuration). Since the metal ion and its oxidation state are identical across all complexes, the magnitude of the crystal field splitting energy (Δ0\Delta_0) depends exclusively on the nature (field strength) of the ligands attached to the metal center.

  2. Spectrochemical Series: According to the spectrochemical series, ligands are arranged in increasing order of their field strength (ability to cause crystal field splitting): F−<H2O<en<CN−\text{F}^- < \text{H}_2\text{O} < \text{en} < \text{CN}^-

  3. Order of Crystal Field Splitting Energy (Δ0\Delta_0): A stronger ligand produces a larger splitting of the dd-orbitals, resulting in a higher value of Δ0\Delta_0. Therefore, the order of Δ0\Delta_0 for the given complexes is: Δ0([CrF6]3−)<Δ0([Cr(H2O)6]3+)<Δ0([Cr(en)3]3+)<Δ0([Cr(CN)6]3−)\Delta_0\left([\text{CrF}_6]^{3-}\right) < \Delta_0\left([\text{Cr}(\text{H}_2\text{O})_6]^{3+}\right) < \Delta_0\left([\text{Cr}(\text{en})_3]^{3+}\right) < \Delta_0\left([\text{Cr}(\text{CN})_6]^{3-}\right)

  4. Matching with Given Values: Arranging the values in List - II in increasing order: 15,060 cm−1<17,400 cm−1<22,300 cm−1<26,600 cm−115,060\text{ cm}^{-1} < 17,400\text{ cm}^{-1} < 22,300\text{ cm}^{-1} < 26,600\text{ cm}^{-1}

    By comparing the order of ligand field strengths with the Δ0\Delta_0 values, we get:

    • B. [CrF6]3−[\text{CrF}_6]^{3-} (weakest ligand, F−\text{F}^-) →\rightarrow I. 15,060 cm−115,060\text{ cm}^{-1}
    • C. [Cr(H2O)6]3+[\text{Cr}(\text{H}_2\text{O})_6]^{3+} (H2O\text{H}_2\text{O}) →\rightarrow II. 17,400 cm−117,400\text{ cm}^{-1}
    • D. [Cr(en)3]3+[\text{Cr}(\text{en})_3]^{3+} (en\text{en}) →\rightarrow III. 22,300 cm−122,300\text{ cm}^{-1}
    • A. [Cr(CN)6]3−[\text{Cr}(\text{CN})_6]^{3-} (strongest ligand, CN−\text{CN}^-) →\rightarrow IV. 26,600 cm−126,600\text{ cm}^{-1}

Thus, the correct matching is: A-IV, B-I, C-II, D-III\text{A-IV, B-I, C-II, D-III}

Correct Option: D

Match Chromium III Complexes with Crystal Field Splitting Energy Values | Chemistry PYQ Solution - JEE Challenger