Naming Complexes

Chloride, Cl- is one element Naming complexes Definition: A complex is a central metal ion surrounded by ligands Examples: [Cu(H2O)6]2+ and [CuCl4]2- Round brackets, ( ) are used around ligands comprising of more than one element such as: Water (H2O), ammonia (NH3), hydroxide ions (OH-) Square brackets, [ ] are used to enclose the complex, with the overall charge written outside Chloride, Cl- is one element

Naming complexes The name of a complex gives you information about: The number of each type of ligand The identity of each ligand The identity of the central metal ion and its oxidation state Example: [Cr(H2O)4(OH)2]+ 4 water (H2O) ligands and 2 hydroxide (OH-) ligands Chromium(III) ion, Cr3+

Number of ligands When there are two or more ligands around the central metal ion, the number is shown by a prefix Example: [Cu(H2O)6]2+ Name: Hexa Number of ligands Prefix 2 Di 3 Tri 4 Tetra 5 Penta 6 Hexa

Name of ligands The identity of each type of ligand is shown by a name This name is not identical to the name of the ligand Example: [Cu(H2O)6]2+ Name: Hexaaqua Ligand Name in complex Water Aqua Ammonia Ammine Chloride Chloro Hydroxide Hydroxo Cyanide Cyano

Names of metals The name of the metal changes depending on whether the complex is positively or negatively charged If the complex is positively charged, the metal is identified by its normal name, with the oxidation state shown in brackets Example: [Cu(H2O)6]2+ Name: Hexaaquacopper(II) Example: [Cu(H2O)6]+ Name: Hexaaquacopper(I) Example: [Co(H2O)6]2+ Name: Hexaaquacobalt(II)

Name in negatively charged complex Names of metals If the complex is negatively charged, the oxidation state of the metal is still shown in brackets But the ending of the metal’s name has the suffix ate added to it Metal Name in negatively charged complex Chromium Chromate Cobalt Cobaltate Copper Cuprate Iron Ferrate Manganese Manganate

Name in negatively charged complex Names of metals Metal Name in negatively charged complex Chromium Chromate Cobalt Cobaltate Copper Cuprate Iron Ferrate Manganese Manganate Nickel Nickelate Silver Argentate Vanadium Vanadate

Naming complexes It is acceptable to have two letter a’s next to each other, such as hexaaqua or hexaamine Formula Name [Ag(NH3)2]+ Diamminesilver(I) [Co(H2O)6]2+ Hexaaquacobalt(II) [Co(NH3)6]2+ Hexaamminecobalt(II) [CoCl4]2- Tetrachlorocobaltate(II) [AgCl2]- Dichloroargenate(I) [Fe(H2O)6]2+ Hexaaquairon(II) [Ag(CN)2]- Dicyanoargenate(I)

Naming complexes If two or more ligands are present in a complex, they are named in alphabetical order It is the name of the ligand which is written in alphabetical order, not the numbering prefix Examples: [Cu(H2O)5(OH)]+ Pentaaquahydroxocopper(II) [Cu(H2O)2(NH3)4]2+ Tetraamminediaquacopper(II) [Fe(H2O)4(OH)2]+ Tetraaquadihydroxoiron(III)

Writing formulae When you write the formula of a complex: First write the symbol of the central metal ion Then write the symbols of the ligands in alphabetical order Include brackets and work out the charge on the outside Example: Tetraaquadichlorochromium(III) ion [CrCl2(H2O)4]+ Not [Cr(H2O)4Cl2]+

Writing formulae First write the symbol of the central metal ion Then write the symbols of the ligands in alphabetical order Include brackets and work out the charge on the outside Name Formula Diaquasilver(I) [Ag(H2O)2]+ Hexaaquavanadium(III) [V(H2O)6]3+ Tetracyanonickelate(II) [Ni(CN)4]2- Tetrachloroferrate(II) [FeCl4]2- Diaquatetrahydroxochromate(III) [Cr(H2O)2(OH)4]- Triaaquatrihydroxocuprate(II) [Cu(H2O)3(OH)3]-