Which of the following ligands is considered a chelating ligand?

Solution

1. A chelating ligand must have two or more donor atoms to form a ring.
2. ${\text{NH}}_3$, ${\text{Cl}}^{-}$, and ${\text{H}}_2\text{O}$ are monodentate ligands.
3. Ethylenediamine ($\text{en}$) is ${\text{NH}}_2{\text{CH}}_2{\text{CH}}_2{\text{NH}}_2$, which acts as a bidentate ligand.
4. Hence the answer is (B).