Bonding In Coordination Complexes: Valence Bond Theory (VBT) Notes | Study Inorganic Chemistry - Chemistry

Chemistry: Bonding In Coordination Complexes: Valence Bond Theory (VBT) Notes | Study Inorganic Chemistry - Chemistry

The document Bonding In Coordination Complexes: Valence Bond Theory (VBT) Notes | Study Inorganic Chemistry - Chemistry is a part of the Chemistry Course Inorganic Chemistry.
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BONDING IN COORDINATION COMPLEXES


There are three theories proposed to explain the nature of bonding in coordination complexes.

  • Valence Bond Theory (VBT)
  • Crystal Field Theory (CFT)
  • Ligand Field Theory (LFT) or Molecular Orbital Theory (MOT)

 Valence Bond Theory

This theory is mainly based on following assumptions:

  • The central metal cation or atom makes available a no. of vacant s, p and or d orbitals equal to its coordination no. to form coordinate bonds with ligands.
  • These vacant metal orbitals hybridised to form new set of equivalent hybrid orbitals. These hybrid orbitals have same geometry and energy.
  • The ligands having lone pair of electrons overlaps with these hybrid orbitals to form a coordinate covalent bond.
    Bonding In Coordination Complexes: Valence Bond Theory (VBT) Notes | Study Inorganic Chemistry - Chemistry
     
  • The hybridisation and geometry of the complex is dependent on the coordination no. and the no. of unpaired electrons (magnetic moment) of the metal ion or atom.
  • Ligands are of two types:
    a. Strong field ligands or simply strong ligands. These are either carbon donor or nitroge n donor. For example, CO, CN etc.
    b. Weak field ligands or simply weak ligands. These are halogen (F, Cl etc.) and majorit y of oxygen donor ligands.
  • Strong ligands have t he tendenc y to pair up d-electrons of metal atom or ion to provide necessary orbitals for hybridisation, if required. On the other hand, weak ligands do not have tendency to pair up d electrons.
  • In octahedral complexes, the central metal cation is eit her d2sp3 or sp3d2 hybridised. The complexes having d2sp3 hybridisation are called inner orbital complexes as they involve the inner d orbital (n-1) d orbital for hybridisation.
  • The complexes having sp3dorbitals are called outer orbital complexes as they involved and orbitals for hybridisation.
  • In case of second and third series transit ion metal complexes, pairing takes place irrespective of the nature of ligands due to diffused nature of 4d and 5d orbitals. Hence, these transition metals only form inner orbital complexes.
  • The complexes having one or more unpaired electrons are paramagnetic and the complexes which do not have any unpaired electrons are called diamagnetic complexes.

Here is the table which consists of geometries which are found in coordination complexes.

Bonding In Coordination Complexes: Valence Bond Theory (VBT) Notes | Study Inorganic Chemistry - ChemistryBonding In Coordination Complexes: Valence Bond Theory (VBT) Notes | Study Inorganic Chemistry - Chemistry

Hybridization schemes for the σ-bonding frameworks of different geometrical configuration of ligand donor atoms

 Bonding In Coordination Complexes: Valence Bond Theory (VBT) Notes | Study Inorganic Chemistry - Chemistry
Bonding In Coordination Complexes: Valence Bond Theory (VBT) Notes | Study Inorganic Chemistry - Chemistry
Bonding In Coordination Complexes: Valence Bond Theory (VBT) Notes | Study Inorganic Chemistry - Chemistry
Bonding In Coordination Complexes: Valence Bond Theory (VBT) Notes | Study Inorganic Chemistry - Chemistry

 

Various higher level geometries are given below

Bonding In Coordination Complexes: Valence Bond Theory (VBT) Notes | Study Inorganic Chemistry - Chemistry  Bonding In Coordination Complexes: Valence Bond Theory (VBT) Notes | Study Inorganic Chemistry - Chemistry  Bonding In Coordination Complexes: Valence Bond Theory (VBT) Notes | Study Inorganic Chemistry - Chemistry  Bonding In Coordination Complexes: Valence Bond Theory (VBT) Notes | Study Inorganic Chemistry - Chemistry  Bonding In Coordination Complexes: Valence Bond Theory (VBT) Notes | Study Inorganic Chemistry - Chemistry
Bonding In Coordination Complexes: Valence Bond Theory (VBT) Notes | Study Inorganic Chemistry - Chemistry  Bonding In Coordination Complexes: Valence Bond Theory (VBT) Notes | Study Inorganic Chemistry - Chemistry  Bonding In Coordination Complexes: Valence Bond Theory (VBT) Notes | Study Inorganic Chemistry - Chemistry  Bonding In Coordination Complexes: Valence Bond Theory (VBT) Notes | Study Inorganic Chemistry - Chemistry

The document Bonding In Coordination Complexes: Valence Bond Theory (VBT) Notes | Study Inorganic Chemistry - Chemistry is a part of the Chemistry Course Inorganic Chemistry.
All you need of Chemistry at this link: Chemistry
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