A coordination complex is a compound where a metal is bonded to ligands. It can be neutral or charged.
A complex ion is a coordination complex that has an overall positive or negative charge. It usually exists with counter-ions to balance the charge.
In short:
- Coordination complex: metal + ligands, may be neutral or charged.
- Complex ion: charged metal-ligand complex.
Example:
- Coordination complex: a neutral compound with metal and ligands.
- Complex ion: [Fe(CN)₆]³⁻ (anion).