Question

Ethylene diaminetetraacetate ion is a/an:

• A. hexadentate ligand
• B. ambidentate ligand
• C. monodentate ligand
• D. bidentate ligand

Answer 1

The Correct Option is A

To determine the nature of the ethylene diaminetetraacetate ion (EDTA), it is important to understand the concept of ligands and their classifications based on the number of binding sites they possess. 

1. **Definition of Ligands**: Ligands are atoms, ions, or molecules that can donate a pair of electrons to the central metal atom/ion in a coordination complex.

2. **Types of Ligands based on Denticity**:

• Monodentate Ligands: These ligands possess only one donor site. An example is Cl^-.
• Bidentate Ligands: These ligands have two donor sites that allow them to bind at two places on the central atom. An example is ethylenediamine.
• Ambidentate Ligands: These ligands can bind through different atoms, but only one at a time. A classic example is NO₂^- (can bind through nitrogen or oxygen).
• Hexadentate Ligands: These ligands have six donor sites, allowing them to form up to six bonds with a central metal ion.

 

3. **Nature of EDTA**: EDTA is an ethylene diamine tetraacetic acid that can donate six pairs of electrons from its two nitrogen and four oxygen atoms. Thus, EDTA is classified as a hexadentate ligand.

4. **Conclusion**: EDTA, being able to form six bonds with a central metal ion, is best described as a hexadentate ligand.