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How are coordination compounds named under International Union of Pure and Applied Chemistry rules?
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coordination compound
Coordination compounds contain a central metal atom surrounded by nonmetal atoms or groups of atoms, called ligands. For example, vitamin B12 is made up of a central metallic cobalt ion bound to multiple nitrogen-containing ligands.
The systematic naming of coordination compounds follows guidelines established by the International Union of Pure and Applied Chemistry (IUPAC). Key conventions include:1
- Order of Components: For salts, the cation is named before the anion.1
- Naming Complexes: In neutral and cationic complexes, ligands are named first, followed by the metal. For anionic complexes, the metal name ends in the suffix -ate.1
- Ligand Nomenclature: Anionic ligands ending in -ide, -ite, or -ate have their final -e replaced by -o (e.g., -ido, -ito, -ato). Ligands are listed in alphabetical order, ignoring multiplicative prefixes.1
- Multiplicity: The number of ligands is indicated by prefixes such as di-, tri-, and tetra-. For complex ligands, prefixes like bis-, tris-, and tetrakis- are used.1
- Metal Oxidation State: The metal's oxidation number is typically indicated by Roman numerals in parentheses following the metal name.1
- Polynuclear Complexes: Bridging ligands are identified by the prefix mu (-).1
Beyond these systematic rules, many compounds retain traditional names based on their color or discoverer.1