Question

Low spin tetrahedral complexes are not known.

Answer 1

When four ligands surround the metal ion in a tetrahedral molecule, this is known as sp³ hybridization. The d-orbitals separate into two groups during crystal field splitting: one group has a larger energy than the other. The splitting energy of d orbitals is significantly lower than the pairing energy because the ligands in a tetrahedral complex approach between the axes rather than directly approaching the d-orbitals. As a result, electrons jump to the higher-energy d-orbitals instead of pairing, forming high-spin complexes.