Question

The magnitude of crystal field stabilization energy ($CFSE$ or ${\Delta }_t$) in tetrahedral complexes is considerably less than in the octahedral field, because

• A. there are only four ligands instead of six, so the ligand field is only 2/3 the size, hence the ${\Delta }_t$ is only 2/3 the size
• B. the direction of the orbitals does not coincide with the direction of the ligands. This reduces the crystal field stabilisation energy $({\Delta }_t)$ by further 2/3
• C. both points a and b are correct
• D. both points a and b are wrong

Answer 1

Answer: (C)

In tetrahedral complexes, there are only four ligands whereas in octahedral complexes, six ligands are observed.
Therefore, tetrahedral complexes show only $2/3$ size than octahedral complexes, hence $\Delta t$ is only $2/3$ of the size.
Also the direction of the orbitals does not coincide with the direction of the ligands.
This reduces the crystal field stabilisation energy $({\Delta }_t)$ by further $2/3$.