Question

Define the following terms : (a) Ambidentate ligand (b) Crystal field splitting energy

Hint:

"Ambi" means both; an ambidentate ligand has two distinct donor atoms but uses only one per coordinate bond.

Answer 1

Step 1: Concept
Key terminology in Coordination Chemistry.

Step 2: Meaning
Certain unidentate ligands possess multiple donor atoms but bond using only one at a time. Furthermore, the d-orbitals of a central metal ion split in energy when surrounded by ligands.

Step 3: Analysis
A ligand that can attach through two different atoms is called ambidentate (e.g., $NO_{2}^{-}$ via N or O). The energy gap between the resulting sets of d-orbitals ($t_{2g}$ and $e_{g}$) is the crystal field splitting energy (CFSE).

Final Answer: (a) Ambidentate ligand: A unidentate ligand that can coordinate to the central metal atom or ion through two different donor atoms (e.g., $SCN^{-}$ can bind through S or N). (b) Crystal field splitting energy: The energy difference between the two sets of degenerate d-orbitals ($t_{2g}$ and $e_{g}$) created by the electrostatic field of the approaching ligands.