Crystal Field Theory
Crystal field theory established in 1929 explains the interaction of the metal ion and the ligand as a pure electrostatic reaction , where the ligands are considered as the point charges in vicinity of the atomic orbitals of the central atom.
The extension and development of the crystal field theory takes into account the partial covalent nature of bonds that exists between the ligand and the metal atom.
It is mainly through the application of molecular orbital theory. Crystal field theory often termed as ligand field theory. The theory points out anions as point charges and neutral molecules as dipoles.
Therefore the theory was proposed as it provided description on the metal-ligand bond
As an ionic bond arises only from the electrostatic interactions between the metal ions and ligands. Crystal field theory considers anions as point charges and neutral molecules as dipoles.
When there exists no bond of the transition metals to any ligand, their d orbitals are degenerate, meaning they have the same energy.
When bonding with other ligands takes place, as a result of different symmetries
Therefore the d orbitals and the inductive effect of the ligands on the electrons, the d orbitals split apart and dont break.
Features of Crystal Field Theory
·The Crystal field theory (CFT) is a model for the bonding interaction between transition metals and ligands.
In other words it describes the effect of attraction in cations and ligands.
The attraction between the positive charge of the metal cation and negative charge on the non-bonding electrons of a ligand.
Therefore, When the ligand approaches the central metal ion the dangerously of electronic orbital states, usually d or f orbitals, breaks due to the statistic electric field by a surrounding charge distribution.
In other words, CFT successfully accounts for some magnetic properties, colours, hydration energies of transition metal complexes,
CFT does not help to describe bonding ,The net change in crystal energy resulting from the orientation of d orbitals of a transition metal cation inside a coordinating group of anions also called ligands.
However an important factor of transition is that they have the ability to form complexes, the complex form may be a central metal ion or an atom surrounded by many ligands.
The interaction that occur between these ligands with the central metal atom or ion is subject to the theory.
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