Any combination of a cation associated with molecules or anions
containing unshared pairs of electrons. The interaction can range from
purely electrostatic to that approaching covalent character.
With respect to a complex we further define:
- Metal Cation - The central metal atom in the complex
- Ligand(s) – the anions or molecules involved in forming the complex with the central metal cation
- Ligand Atom – the particular atom involved in the interaction with the central metal atom