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Questions
What is the difference between a weak field ligand and a strong field ligand?
Explain the difference between a weak field ligand and a strong field ligand.
Write the difference between a strong field ligand and a weak field ligand.
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Solution
| S.No. | Weak Field Ligand | Strong Field Ligand |
| 1. | A ligand that produces a small splitting of the d-orbitals in the central metal ion. | A ligand that produces a large splitting of the d-orbitals in the central metal ion. |
| 2. | These are the ligands used in octahedral complexes in which the crystal field stabilization energy Δ° is less than the pairing energy (P) in a single orbital. | These are the ligands used in octahedral complexes in which the crystal field stabilization energy Δ° is greater than the pairing energy (P). |
| 3. | Complexes formed by these ligands are also known as high-spin complexes. | Complexes formed by these ligands are also known as low-spin complexes |
| 4. | The complexes formed are generally paramagnetic. | The complexes formed are mostly diamagnetic or relatively less paramagnetic. |
| 5. | Examples of weak field ligands include I−, Br−, Cl−, and H2O. | Examples of strong field ligands include NH3, CN−, Co. |
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| Column I (Complex ion) | Column II (Hybridisation, number of unpaired electrons) |
| A. \[\ce{[Cr(H2O)6]^{3+}}\] | 1. dsp2, 1 |
| B. \[\ce{[Co(CN)4]^{2-}}\] | 2. sp3d2, 5 |
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| 5. sp3d2, 2 |
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- Both the complexes can be high spin.
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|
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|
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(a) Out of ligands "A", "B", "C" and "D", which ligand causes maximum crystal field splitting? Why?
OR
Which of the two, “A” or “D” will be a weak field ligand? Why?
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(Given: If 560 - 570 nm of light is absorbed, the colour of the complex observed is violet.)
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- [CrA6]3-
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