Question

Low spin tetrahedral complexes are not known. 

Hint:

Low-spin complexes are more commonly seen in octahedral geometries where the ligand field splitting is stronger.

Answer 1

Low spin tetrahedral complexes are not known because tetrahedral complexes typically have a weaker ligand field splitting energy compared to octahedral complexes. In a tetrahedral field, the splitting energy (\(\Delta_T\)) is smaller, which does not create a significant enough energy difference between the d-orbitals to cause pairing of electrons. Therefore, in a tetrahedral complex, the electrons tend to occupy all available orbitals singly (high-spin state), and low-spin tetrahedral complexes are not stable.