Naming Coordination Compounds
Coordination compounds are a group of compounds in which a central metal ion is bonded to electron rich ligands. The number and type of ligands vary which causes some confusion when naming the compound. A number of rules have been put in place to help name the coordination compound or coordination complex.
1. The name of the cation comes before the anion.
- The oxidation number of the cation is given in parentheses as a Roman numeral after the cation name if the cation can have more than one oxidation state.
2. The ligands are named before the cation and are in alphabetical order.
- Prefixes are used to denote the number of ligands (the prefixes do not factor in to alphabetical order).
- If the ligand is an anion, they will end in the letter o.
- If the ligand already contains a Greek prefix (di, tri, tetra...) then alternate prefixes are used.
3. If the coordination complex ion is negative, then it will end in ~ate.
Examples:
1. Name the following complex ion: [Fe(CN)6]-4
Answer: Hexacyanoferrate (II) ion
2. Name the following coordination compound: [Pt(NH3)5Cl]Br3
Answer: Pentaaminechloroplatinum (IV) bromide
1. The name of the cation comes before the anion.
- The oxidation number of the cation is given in parentheses as a Roman numeral after the cation name if the cation can have more than one oxidation state.
2. The ligands are named before the cation and are in alphabetical order.
- Prefixes are used to denote the number of ligands (the prefixes do not factor in to alphabetical order).
- If the ligand is an anion, they will end in the letter o.
- If the ligand already contains a Greek prefix (di, tri, tetra...) then alternate prefixes are used.
3. If the coordination complex ion is negative, then it will end in ~ate.
Examples:
1. Name the following complex ion: [Fe(CN)6]-4
Answer: Hexacyanoferrate (II) ion
- The prefix hexa is used for the six cyanide ligands.
- The ligand is an anion so it ends in o.
- The complex ion is negative so the ion ends in ~ate.
- The oxidation state of the iron is +2 which is represented by the Roman numeral.
2. Name the following coordination compound: [Pt(NH3)5Cl]Br3
Answer: Pentaaminechloroplatinum (IV) bromide
- The prefix penta is used for the five NH3 (amine) ligands.
- The Cl ligand is an anion and ends in o.
- The platinum has an oxidation state of +4 which is represented by the Roman numeral.
- The anion is bromine, which has the suffix ~ide.
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Related Links: Chemistry Transition Metals Chelating Agents Coordination Compounds |
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