Question

Classify the following ligand based on the number of donor atoms.
1.NH3 2.en 3.ox2- 4.triamino triethylamine 5.pyridine

Answer 1

Answer :

(1) $NH_3$ is monodentate ligand.

(2) 'en' (ethylene diamine), $H_2N-CH_2-CH_2-NH_2$ is bidentate ligand.

(3) $ox^{2-}$ (oxalato ion), $C_2O_4^{2-}$ is bidentate ligand.

(4) Triamino triethylamine is tetradentate ligand.

(5) Pyridine is monodentate ligand.

Explanation :

Depending on the number of donor atoms of a ligand coordinated to the central metallic atom, the ligands have been classified as, Monodentate and Polydentate.

(1) Monodentate : The ligands which have only one donor atom.

(2) Polydentate : The ligands which have more that one donor atom. These may be bidentate, tridentate, tetradentate and so on.

Bidentate ligands : Bidentate ligands have two lone pairs and both of which can bond to the central metal ion. Bidentate ligands may be neutral molecules or anions.

Tridentate ligands : Tridentate ligands have three lone pairs and the three lone pair can bond to the central metal ion.

Tetradentate ligands : Tetradentate ligands have two lone pairs and the four lone pair can bond to the central metal ion.

The structure of given ligands are shown below.