Question

Why crystal field splitting energy is less for tetrahedral and octahedral

Answer 1

In tetrahedral field none of the d-orbitals point directly towards the ligands lowering the electron-electron repulsion and therefore splitting of energy is less compare to the octahedral field and less number of ligands produces less crystal field splitting. Since the magnitude of crystal field splitting energy in tetrahedral field is small and always less than pairing energy. So, the pairing of electrons will never be energetically favourable. Thus all the tetrahedral complexes are high spin complexes. Coloured because of d-d transition (i.e.,e1t02−>e0t12)(i.e.,e1t20−>e0t21) as less energy required for transition.

Answer 2

In a tetrahedral crystal field splitting, the d-orbitals again split into two groups, with an energy difference of Δtet. ... Furthermore, since the ligandelectrons in tetrahedral symmetry are not oriented directly towards the d-orbitals, the energy splitting will belower than in the octahedral case.