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Anujitha from SHARJAH INDIAN SCHOOL, asked a question
Subject: Chemistry , asked on 30/1/13

what are the limitations of valence bond theory?


Sumeet Malik , Meritnation Expert added an answer, on 31/1/13

Limitation of Valence Bond Theory

  • Lots of assumption are involved
  • Colour exhibition by coordination compounds is not explained.
  • For a compound of coordination number 4 is tetrahedral or square planar cannot be exactly predicted.
  • Weak and strong ligands cannot be distinguished.
  • It cannot explain why certain ligands form high spin and while others low spin complexes.

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Sanya From International Indian School, added an answer, on 31/1/13
26 helpful votes in Chemistry

 The valence bond theory was fairly successful in explaining qualitatively the geometry and magnetic behaviour of the complexes. But, it could not explain the following :

(i) The origin of their absorption spectra could not be explained.

(ii) Why did different complexes of the same metal show different colours.

(iii) Relative stabilities of different complexes could not be explained.

(iv) Why should certain ligands form high spin, while others low spin complexes.

(v) it assumes all  bonds  are localized  bonds . As we will see, this is not a valid assumption.

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