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

  • 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.


Related Links:

Chemistry
Transition Metals
Chelating Agents
Coordination Compounds



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