The magnitude of crystal field stabilisation energy (CFSE or Δt) in tetrahedral complexes is considerably less than in the octahedral field. Because
(a) There are only 4 ligands instead of six.
So the ligand field in only 2/3 the size, hence Δt, is only 2/3 the size.
(b) the direction of orbitals does not coincide with the direction of the ligands. This reduces the crystal field stabilisation energy (Δt) by further 2/3.
(c) both (a) and (b) are correct
(d) both (a) and (b) are wrong.
