Nomenclature of Coordination Compounds

Before IUPAC standardised things, coordination compounds were simply named after their discoverers -- K[PtCl₃(C₂H₄)] was 'Zeise's salt' and [Pt(NH₃)₄][PtCl₄] was 'Magnus's green salt'. With thousands of synthesised complexes now known, IUPAC's 2005-recommendation system names them systematically instead, starting from the first and most general rule: the cation is always named first, followed by the anion, regardless of whether either ion is simple or itself complex -- so in K₄[Fe(CN)₆] the simple cation K⁺ is named before [Fe(CN)₆]⁴⁻; in [Co(NH₃)₆]Cl₃ the complex cation [Co(NH₃)₆]³⁺ is named before the simple an …