An example of a cation complex is [Co(NH₃)₆]³⁺.
Coordination complexes, also known as coordination compounds, are fascinating chemical structures formed by a central metal atom or ion surrounded by a group of molecules or ions called ligands. These ligands bond to the central metal atom through coordinate covalent bonds.
Depending on the overall charge of the complex, it can be a cation complex (positively charged), an anion complex (negatively charged), or a neutral complex.
Understanding Cation Complexes
A cation complex is simply a coordination complex that carries a net positive electrical charge. This positive charge arises from the charges of the central metal ion and the ligands attached to it. If the positive charge of the metal ion outweighs the negative charges of the ligands (or if the ligands are neutral), the resulting complex will be positively charged.
Example of a Cation Complex: [Co(NH₃)₆]³⁺
According to the reference provided: "Example of coordination complexes and compounds are: Complex Cation: [Co(NH3)6]3+ Complex Anion: [CoCl4(NH3)2]−".
This explicitly identifies [Co(NH₃)₆]³⁺ as an example of a complex cation. Let's break down what this means:
- Co: This is the central metal ion, Cobalt. In this complex, Cobalt is in the +3 oxidation state (Co³⁺).
- NH₃: These are the ligands, Ammonia molecules. Ammonia is a neutral ligand, meaning it carries no charge.
- 6: This number indicates that there are six Ammonia ligands bonded to the central Cobalt ion.
- [ ]³⁺: The brackets enclose the entire complex unit (the metal ion and its ligands), and the superscript ³⁺ indicates the overall charge of the complex.
Since the Cobalt ion has a +3 charge and the six Ammonia ligands are neutral (6 x 0 = 0), the total charge of the complex is +3 + 0 = +3. Hence, [Co(NH₃)₆]³⁺ is a positively charged complex, making it a cation complex.
Components of the Complex
The structure of the complex can be summarized in a table:
| Component | Chemical Formula | Role in Complex | Charge |
|---|---|---|---|
| Central Metal Ion | Co | Central Atom | +3 |
| Ligand | NH₃ | Ligand | 0 |
| Number of Ligands | 6 | Coordination # | N/A |
| Overall Complex | [Co(NH₃)₆]³⁺ | Cation Complex | +3 |
This example clearly illustrates how a metal ion and neutral ligands can combine to form a positively charged coordination entity.
