Explain with two examples each of the following: coordination entity, ligand, coordination number, coordination polyhedron, homoleptic and heterolepti

1)Coordination Entity: Coordination entity is a charged entity having positive or negative charge in which the central atom is surrounded by molecules which may be neutral/negatively charged called Ligands.

Examples:

Cationic Complexes: [Cu(H2O)6]2+ , [Al(H2O)6]3+

Anionic Complexes:  [CuCl4]2- ,  [Al(H2O)2(OH)4]- 

Neutral Complexes: [Co(NH3)4 Cl2] ,[Ni(CO)4]

2)Ligands: Ligands are the neutral or negatively charged entities surrounding the central metal atom of the coordination complex which possesses at least one unshared pair of electrons

Example: F-, Cl-, Br-, I-, H20, and NH3

3)Coordination Number: Coordination Number which is also called as Ligancy is the total number of ligands that are attached to the central metal atom of the coordination complex.

Example: [Cr(NH3)2Cl2Br2]− has Cr3+ as its central cation, and has a coordination number of 6 Al3+ has coordination number 4 in [AlCl4]- but 6 in [AlF6]3-.

4) Coordination polyhedron: Coordination polyhedron is defined as the spatial arrangement of the ligands around the central atom of a coordination complex.

5) Homoleptic complexes: Complexes in which the central metal atom is surrounded only by the same kind of donor groups which are the ligands.

Example : [Ag(CN)2]-,[Fe(CN6)]4+ etc

6) Heteroleptic complexes: Complexes in which the central metal atom is surrounded by more than one kind of donor groups which are the ligands.

Example: [Co(NH3)4 Cl2]+,[Co(NH3)5 Cl]2+