3. Ligands
Ligands is electron donating species( ions or molecules) bound to the Central atom in the coordination entity.
These may be charged or neutral. Ligands are of the following types:
( i) Unidentate It is a ligand, which has one donor site, i. e., the ligand bound to a metal ion through a single donor site. e. g., H2O, NH3, etc.
( ii) Didentate It is the ligand. which have two donor sites.
( iii) Polydentate It is the ligand, which have several donor sites. e. g., [ EDTA ] 4- is hexadentate ligand.