Question

Using the IUPAC norms, write the systematic names of the following.
(i) ${K}_{4}[Fe{(CN)}_{6}]$
(ii) $[Cu{(N{H}_{3})}_{4}]S{O}_{4}$

Answer 1

The IUPAC naming of the coordination compound provides a method to represent and
describe the names and formulas of coordination compounds systematically. The given compounds
are also named with reference to the rules set up by IUPAC.

Complete step by step solution:
The rules of complex nomenclature are given below:
Rule 1: While naming a complex compound, we always name the cation before the anion.
Rule 2: When we see that there are multiple types of ligands present in any coordination compound, we name the ligands in alphabetic order after by the name of central metal atom/ion.
-Name of the anionic ligands ends with ‘o’.
-For neutral ligands, their common name is used
Rule 3: If the names of the ligands have a numerical prefix, then we use the terms like bis, tris, tetrakis.
Rule 4: After naming the ligand in alphabetic order, we name the central metal atom/ion.
-If the complex ion is a cation, we name the metal the same as the element.
-If the complex is an anion, the name of metal ends with the suffix -ate for Latin name.
Rule 5: We give the oxidation state of the metal in the complex as a roman numeral in parentheses.
Rule 6: We name the neutral complex molecule similar to that of the complex cation.
Let us now name see the IUPAC name of the given complex compounds.
(i) ${K}_{4}[Fe{(CN)}_{6}]$:
In the given chemical compound, the cation present is potassium. Its IUPAC name would start from potassium. The ligand present in this compound is the -CN group, which is named as cyano which we get from the name cyanide. Since there are six molecules of cyanide ions therefore we write hexacyano. Now, the central atom is iron and has a +2 oxidation state.
Therefore, the IUPAC name of the compound becomes potassium hexacyanoferrate(II).
(ii) $[Cu{(N{H}_{3})}_{4}]S{O}_{4}$:
In this chemical compound, there is no main cation present rather the main anion is present. The ligand present in the compound is the $-N{H}_{3}$ group, which is named as ammine which we get from the name of the group, amine. And since there are 4 molecules of amine, we write tetraammine. Now, the central atom is copper which has a +2 oxidation state. Therefore the name becomes tetraamminecopper(II). Now the main anion present is the sulphate ion.
Hence, the IUPAC name of the compound becomes tetraamminecopper(II)sulphate.

Note: In the above-given compound, students tend to get confused with ${K}_{3}[Fe{(CN)}_{6}]$ and ${K}_{4}[Fe{(CN)}_{6}]$. Please note that the IUPAC name of the first compound is Potassium hexacyanoferrate(III) and that of latter is potassium hexacyanoferrate(II). There is a difference in oxidation states.