What is meant by a unidentate ligand ? Give an example…

What is meant by a unidentate ligand ? Give an example.

Ans.

A unidentate ligand is a type of ligand that can form only one bond to a central metal ion in a coordination complex. In other words, it has only one donor atom that can donate a pair of electrons to the metal ion.

Unidentate ligands typically have one atom capable of forming a coordinate covalent bond with the metal ion. This can be a lone pair of electrons on an atom, such as nitrogen, oxygen, sulfur, or a halogen, which can be donated to the metal ion.

Examples of unidentate ligands include:

1. Ammonia (NH3): Ammonia has a lone pair of electrons on the nitrogen atom, which can coordinate with a metal ion to form a coordination complex. The nitrogen atom acts as the donor atom, forming a single bond with the metal ion.

2. Chloride ion (Cl-): The chloride ion can serve as a unidentate ligand by donating its lone pair of electrons to a metal ion, forming a single bond.

3. Water (H2O): Water molecules can act as unidentate ligands when coordinating with metal ions. The oxygen atom in water has two lone pairs of electrons, but it can only donate one pair to the metal ion, making it a unidentate ligand.

In each of these examples, the ligands can form only one bond with the central metal ion, making them unidentate ligands.