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Question
What is the spectrochemical series?
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Solution
Crystal field splitting, Δo depends on the field produced by the charge present on the ligand and the metal ion. Some ligands can produce strong fields and in such a case the splitting is more, while others produce weak fields due to which the splitting of d-orbitals is less. Generally, ligands can be arranged in a series in the order of their increasing field strength as follows:
\[\ce{I^- < Br^- < SCN^- < Cl^- < S^2- < F^- < OH^- < C2O^{2-}_4 < H2O < NCS^- < EDTA^{4-} < NH3 < en < CN^- < CO}\]
This type of series is called a spectrochemical series. It is determined by experimental facts based on the absorption of light by complexes formed with different ligands.
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RELATED QUESTIONS
On the basis of crystal field theory, write the electronic configuration for d4 ion if ∆0 < P.
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| A. \[\ce{[Cr(H2O)6]^{3+}}\] | 1. dsp2, 1 |
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Considering crystal field theory, strong-field ligands such as CN–:
The correct order of increasing crystal field strength in following series:
What is crystal field splitting energy?
For octahedral Mn(II) and tetrahedral Ni(II) complexes, consider the following statements:
- Both the complexes can be high spin.
- Ni(II) complex can very rarely below spin.
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- Aqueous solution of Mn (II) ions is yellow in colour.
The correct statements are:
On the basis of crystal field theory, write the electronic configuration for the d5 ion with a weak ligand for which Δ0 < P.
On the basis of crystal field theory, write the electronic configuration for d4 with a strong field ligand for which Δ0 > P.
Read the passage carefully and answer the questions that follow.
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Crystal field splitting by various ligands Metal complexes show different colours due to d-d transitions. The complex absorbs light of specific wavelength to promote the electron from t2g to eg level. The colour of the complex is due to the transmitted light, which is complementary of the colour absorbed. The wave number of light absorbed by different complexes of Cr ion are given below:
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Answer the following questions:
(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?
(b) Which of the complexes will be violet in colour? [CrA6]3- or [CrB6]3+ and why?
(Given: If 560 - 570 nm of light is absorbed, the colour of the complex observed is violet.)
(c) If the ligands attached to Cr3+ ion in the complexes given in the table above are water, cyanide ion, chloride ion, and ammonia (not in this order).
Identify the ligand, write the formula and IUPAC name of the following:
- [CrA6]3-
- [CrC6]3+
On the basis of Crystal Field Theory, write the electronic configuration of d4 ion if Δ0 > P.
The value of the spin only magnetic moment for one of the following configurations is 2.84 BM. The correct one is:
The correct order of the wavelength of light absorbed by the following complexes is:
- [Co(NH3)6]3+
- [Co(CN)6]3−
- [Cu(H2O)4]2+
- [Ti(H2O)6]3+
Choose the correct answer from the options given below:
