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प्रश्न
State the superiority of crystal field theory over valence bond theory.
Why is crystal field theory regarded superior to valence bond theory?
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उत्तर
Despite the constraints mentioned above, crystal field theory outperforms valence bond theory. The crystal field theory is thought to be preferable to the valence bond theory for the following reasons.
- Crystal field theory describes the magnetic properties of complexes in detail and provides an explanation for how magnetic moments vary with temperature. VBT fails to provide these additional details.
- Crystal field theory measures the stability of a complex. With this measure, the geometry gained by a particular complex can be predicted. VBT does not include such a measure.
- Crystal field theory explains certain thermodynamic and kinetic features of complexes. VBT does not offer such an explanation.
- Only crystal field theory can explain the observed d-d transitions in complexes and their hue. The VBT does not explain spectroscopic features or complex coloration adequately.
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संबंधित प्रश्न
Draw figure to show the splitting of d orbitals in an octahedral crystal field.
How are the following conversions carried out?
Benzoic acid into metanitrobenzoic acid.
Why are low spin tetrahedral complexes rarely observed?
Write the electronic configuration of Fe(III) on the basis of crystal field theory when it forms an octahedral complex in the presence of (i) strong field, and (ii) weak field ligand. (Atomic no.of Fe=26)
Draw the structures of the following :
(1) XeF6
(2) IF7
Complete and balance the following reactions:
\[\ce{P4 + H2SO4 ->}\] ______ + ______ + ______
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, \[\ce{[Co(NH3)6]^{3+}}\], \[\ce{[Co(CN)6]^{3-}}\], \[\ce{[Co(H2O)6]^{3+}}\]
Atomic number of \[\ce{Mn}\], \[\ce{Fe}\] and \[\ce{Co}\] are 25, 26 and 27 respectively. Which of the following inner orbital octahedral complex ions are diamagnetic?
(i) \[\ce{[Co(NH3)6]^{3+}}\]
(ii) \[\ce{[Mn(CN)6]^{3-}}\]
(iii) \[\ce{[Fe(CN)6]^{4-}}\]
(iv) \[\ce{[Fe(CN)6]^{3-}}\]
An aqueous pink solution of cobalt (II) chloride changes to deep blue on addition of excess of HCl. This is because:
(i) \[\ce{[Co(H2O)6]^{2+}}\] is transformed into \[\ce{[CoCl6]}^{4-}\]
(ii) \[\ce{[Co(H2O)6]^{2+}}\] is transformed into \[\ce{[CoCl4]}^{2-}\]
(iii) tetrahedral complexes have smaller crystal field splitting than octahedral complexes.
(iv) tetrahedral complexes have larger crystal field splitting than octahedral complex.
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.
Why are low spin tetrahedral complexes not formed?
Give the electronic configuration of the following complexes on the basis of Crystal Field Splitting theory.
\[\ce{[CoF6]^{3-}, [Fe(CN)6]^{4-} and [Cu(NH3)6]^{2+}}\].
Arrange following complex ions in increasing order of crystal field splitting energy (∆O):
\[\ce{[Cr(Cl)6]^{3-}, [Cr(CN)6]^{3-}, [Cr(NH3)6]^{3+}}\].
\[\ce{CuSO4 . 5H2O}\] is blue in colour while \[\ce{CuSO4}\] is colourless. Why?
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:
\[\ce{[CoF6]^{3-}, [Co(H2O)6]^{2+}, [Co(Cn)6]^{3-}}\]
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:
\[\ce{[FeF6]^{3-}, [Fe(H2O)6]^{2+}, [Fe(CN)6]^{4-}}\]
Why are different colours observed in octahedral and tetrahedral complexes for the same metal and same ligands?
The CFSE for octahedral [CoCl6]−4 is 18,000 cm−1. What will be the CFSE for tetrahedral [CoCl3]−2?
In a coordination entity, the electronic configuration of the central metal ion is t2g3 eg1
Draw the crystal field splitting diagram for the above complex.
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:
- Both the complexes can be high spin.
- Ni(II) complex can very rarely below spin.
- With strong field Ligands, Mn(II) complexes can be low spin.
- 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 strong field ligand for which Δ0 > P.
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.
On the basis of Crystal Field Theory, write the electronic configuration of d4 ion if Δ0 > P.
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:
