Coordination Compound or Complex
Definition and meaning of Coordination Compound or Complex in chemistry.
A coordination compound is a structure in which a central metal atom or ion is bonded to one or more ligands through coordinate covalent bonds. The ligands donate electron pairs to the metal center, which acts as an electron-pair acceptor.
In more detail
In a coordination compound, the metal atom or ion acts as a Lewis acid (electron-pair acceptor) and the ligands act as Lewis bases (electron-pair donors). The ligands can be neutral molecules (like ammonia or water) or anions (like chloride or cyanide). The number of ligands bonded to the metal is called the coordination number, which typically ranges from two to eight but is often four or six. Coordination compounds are essential in biology, industry, and materials science, with applications ranging from photosynthesis and oxygen transport to catalysis and industrial processes.
Key facts
| Field | Inorganic Chemistry |
|---|---|
| Central Species | Metal atom or cation |
| Bonding Type | Coordinate covalent bonds |
| Common Example | [Cu(NH3)4]2+ |
The complex ion [Cu(NH3)4]2+ contains a copper(II) ion bonded to four ammonia ligands, giving the solution a characteristic deep blue color.
Frequently asked questions
What is the difference between a ligand and a regular atom in a molecule?
A ligand specifically donates an electron pair to a metal center in a coordinate covalent bond, whereas atoms in regular molecules share electrons more equally or are bonded through other types of chemical bonds.
Are coordination compounds only found in chemistry laboratories?
No, coordination compounds are essential in nature; hemoglobin (iron-based oxygen transport), chlorophyll (magnesium-based photosynthesis), and many enzymes contain coordination complexes.