in an octahedral crystal field t 2g e g ∆ o ∆ o ∆ o - (d xy , d yz , d xz d x - y and d z ) , d x2 - y2 , d z2 d xy , d yz , d xz Energy Figure: . - Crystal field splitting in octahedral field Crystal field splitting in tetrahedral complexes: The approach of ligands in tetrahedral field can be visualised as follows. Consider a cube in which the central metal atom is placed at its centre (i.e. origin of the coordinate axis as shown in the figure).
The four ligands approach the central metal atom along the direction of the leading diagonals drawn from alternate corners of the cube. L L L L X Y Y' X' Z' Z Figure . tetrahedral ligand field XII U5 Coordination XII U5 Coordination - - - - In this field, none of the d orbitals point dirctly towards the ligands,however the t orbitals (d xy , d yz and d zx ) are pointing close to the direction in which ligands are approaching than the e orbitals (d x2-y2 and d z2 ). As a result, the energy of t orbitals increases by /5Δ t and that of e orbitals decreases by /5Δ t as shown below.
when compared to the octahedral field, this splitting is inverted and the spliting energy is less. The relation between the crystal field splitting energy in octahedral and tetrahedral ligand field is given by the expression; Energy orbitals in free ion d Average energy of the d orbitals in a spherical crystal field Splitting of d-orbitals in an tetrahedral crystal field d xy , d yz , d xz (d xy , d yz , d xz d x - y and d z t e ∆ t ∆ t , d x2 - y2 , d z2 ∆ ∆ t o - Figure: . - Crystal field splitting in