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 .