Read the IUPAC Naming Rules Before You Name a Complex
IUPAC naming is mechanical once you fix the order: ligands alphabetically (ignoring multiplying prefixes), then the metal, then its oxidation state in Roman numerals, with '-ate' added only for anionic complexes.
IUPAC Nomenclature is the central idea in this question pattern. Identify the condition in the stem before applying the method below.
Ligands first, alphabetically, then the metal
For [Pt(NH₃)₂Cl₂], 'ammine' comes before 'chlorido' alphabetically, and platinum keeps its own name (a neutral/cationic complex doesn't get the '-ate' suffix): diamminedichloridoplatinum(II) — the oxidation state is +2 here since the two Cl⁻ balance a neutral overall complex.
Anionic complexes get the metal's Latin '-ate' name
When the whole complex ion carries a negative charge, the metal name switches to its Latinate '-ate' form: platinum becomes 'platinate', gold becomes 'aurate'. For a salt built from a cationic gold-en-aqua complex and an anionic gold-oxalato complex, the cation keeps 'gold' and the anion becomes 'aurate': diaquobis(ethylenediamine)gold(III) tris(oxalato)aurate(III).
Going from formula to name and back again
The same alphabetical-ligand, metal-then-oxidation-state logic runs in reverse when you're asked for a formula from a name. Diammine dichlorodicyano chromate(III) tells you: 2 NH₃ + 2 Cl⁻ + 2 CN⁻ around Cr(III); since the complex carries the '-ate' suffix it must be anionic — the four anionic ligands outweigh the +3 metal charge, giving [CrCl2(CN)2(NH₃)₂]-.
OlympIQ exam lens
- ✓Order ligands alphabetically by name, ignoring di-/tri-/tetra- multiplying prefixes.
- ✓A negatively-charged complex ion always gets the metal's Latinate '-ate' name (platinate, aurate, ferrate).
- ✓Oxidation state in Roman numerals comes right after the metal name, derived from overall charge balance.
- ✓When a formula shows two different complex ions as cation and anion, name each independently.
Don't alphabetise by the multiplying prefix (di-, tris-) — 'dichlorido' is alphabetised under 'c', not 'd'. And the '-ate' suffix only applies when the complex ion itself is anionic, not just because an anion appears somewhere in the full salt.
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