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प्रश्न
On the basis of crystal field theory explain why Co(III) forms paramagnetic octahedral complex with weak field ligands whereas it forms diamagnetic octahedral complex with strong field ligands.
उत्तर
With weak field ligands; ∆0 < p, the electronic configuration of Co (III) will be \[\ce{t^4_{2g} e^2_g}\] and it has 4 unpaired electrons and is paramagnetic. With strong field ligands, ∆0 > p, the electronic configuration will be \[\ce{t^6_{2g} e^0_g}\]. It has no unpaired electrons and is diamagnetic.
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संबंधित प्रश्न
On the basis of crystal field theory, write the electronic configuration for d4 ion if ∆0 < P.
Draw the structures of the following :
(1) XeF6
(2) IF7
The colour of the coordination compounds depends on the crystal field splitting. What will be the correct order of absorption of wavelength of light in the visible region, for the complexes, \[\ce{[Co(NH3)6]^{3+}}\], \[\ce{[Co(CN)6]^{3-}}\], \[\ce{[Co(H2O)6]^{3+}}\]
Match the complex ions given in Column I with the hybridisation and number of unpaired electrons given in Column II and assign the correct code:
| 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 |
| C. \[\ce{[Ni(NH3)6]^{2+}}\] | 3. d2sp3, 3 |
| D. \[\ce{[MnF6]^{4-}}\] | 4. sp3, 4 |
| 5. sp3d2, 2 |
Using crystal field theory, draw energy level diagram, write electronic configuration of the central metal atom/ion and determine the magnetic moment value in the following:
\[\ce{[CoF6]^{3-}, [Co(H2O)6]^{2+}, [Co(Cn)6]^{3-}}\]
Considering crystal field theory, strong-field ligands such as CN–:
Crystal field stabilising energy for high spind4 octahedral complex is:-
Using crystal field theory, write the electronic configuration of d5 ion, if Δ0 > P.
For octahedral Mn(II) and tetrahedral Ni(II) complexes, consider the following statements:
(i) Both the complexes can be high spin.
(ii) Ni(II) complex can very rarely below spin.
(iii) With strong field Ligands, Mn(II) complexes can be low spin.
(iv) Aqueous solution of Mn (II) ions is yellow in colour.
The correct statements are:
Read the passage carefully and answer the questions that follow.
|
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:
|
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+
