What is meant by unidentate, didentate and ambidentate ligands ? Give two examples for each.

Explanation

i) Unidentate ligands : Ligands which can coordinate to central metal atom or ion through only one donor atom are called unidentate ligands. For example, `Cl^(-) and NH_3`.
ii) Didentate ligands : Ligands which have two donor atoms and can co-ordinate to the central metal atom or ion at two positions are called didentate ligands. For example, ethylenediamine (en),i.e, `(H_2N - CH_2 - CH_2- NH_2)`
iii) Ambidentate ligands : The unidentate ligands which can coordinate to the central metal atom or ion through more than one site are called ambidentate ligaqds. For example, `NO_2^(-) and SCN^(-)` ions.