Coordination Entity Vs. Coordination Sphere

Definition:

A coordination entity is a compound or ion that contains a metal atom or ion, which coordinates with a group of surrounding molecules or ions known as ligands. Coordination sphere, on the other hand, refers to the central metal ion and its surrounding ligands.

Composition:

A coordination entity consists of a central metal ion or atom and its surrounding ligands, which are usually anions or neutral molecules. The coordination sphere, on the other hand, consists of the central metal ion and its inner sphere, which includes the ligands directly coordinated to the metal ion.

Structure:

The coordination entity has an overall three-dimensional structure, which is determined by the number and arrangement of ligands around the central metal ion. The coordination sphere, however, is a two-dimensional representation of the complex, which shows all the ligands coordinated to the central metal ion.

Charge:

The coordination entity has a charge that is equal to the charge on the central metal ion. This charge is the sum of the charges on the metal ion and the ligands. The coordination sphere, however, does not have a charge as it is a representation of the complex and not an actual entity.

Examples:

An example of a coordination entity is [Fe(CN)6]4-, which consists of a central iron ion coordinated to six cyanide ligands. An example of a coordination sphere is [Cu(NH3)4(H2O)2]2+, which consists of a central copper ion coordinated to four ammonia ligands and two water molecules.

Conclusion:

In summary, a coordination entity refers to the entire complex consisting of a central metal ion and its surrounding ligands, while the coordination sphere refers to the central metal ion and its inner sphere of ligands.