Question

What are monodentate ligands? Write one example.

Answer 1

First we should know what ligand is- so a ligand is an ion or molecule, which donates a pair of electrons to the central metal atom or ion to form a coordination complex. The word ligand is from Latin, which means “tie or bind”.

Complete step by step answer:

A ligand is an ion or molecule that binds to a central metal atom to form a coordinate complex. Ligands are electron donors; they donate its lone pair of electrons to central metal ions in order to form complex compounds. ligands may be negatively charged or neutral in nature. Whereas central metal ions are electron acceptors, they accept electrons donated by ligands.
Here a single ligand L, which could be water or any other, donates a pair of electrons to form a bond with a metal atom M.
$L\rightarrow M$
Ligands can be classified on the basis of various things. The most important classification on the basis of their binding site with the central metal ion.They are ions/molecules with lone pair of electrons coordinate to empty d-orbitals of transition metal ions
On the basis of their donor site they can be classified as monodentate, bidentate, poly and ambidentate ligands.
Monodentate ligands-These are the ligands which coordinate to only one site to central metal ions i.e. only one pair of electrons can be donated to central metal ions. For example:
$Cl^{-}, Br^{-}, SO_{4}^{2-}, NH_{3}, H_{2}O$
We must be aware about denticity, it refers to the number of donor groups in ligands that bind to central metal atoms through coordinate bonds.

Note:
The most important way of classifying ligands is by the quantity of points at which they're attached to, or sure to, the metal center. This is the denticity. Ligands with one potential donor atom are monodentate. Polydentate ligand is a ligand this is connected to an important steel ion by means of bonds from or more donor atoms.