Question

Write IUPAC names of the following coordination compounds:

(i) \([Ag(NH_3)_2][Ag(CN)_2]\)

(ii) \(K_3[Fe(C_2O_4)_3]\)

Hint:

To name a coordination compound, name the cation first and then the anion.

Answer 1

Concept:
To name a coordination compound, name the cation first and then the anion. Inside a complex ion, name the ligands in alphabetical order with their number prefixes, then the metal, and show the metal's oxidation state in Roman numerals. If the complex ion is negative, the metal name ends in -ate.

Step 1 (part i):
The compound \([Ag(NH_3)_2][Ag(CN)_2]\) has both a complex cation and a complex anion. In the cation \([Ag(NH_3)_2]^+\), the ligand is ammine (NH3) and silver is +1, so it is diamminesilver(I). In the anion \([Ag(CN)_2]^-\), the ligand is cyano (CN) and silver is +1; since the ion is negative the metal is named argentate, so it is dicyanidoargentate(I).
Name: diamminesilver(I) dicyanidoargentate(I).

Step 2 (part ii):
The compound \(K_3[Fe(C_2O_4)_3]\) has potassium as the cation. In the anion, the ligand is oxalato (C2O4, a bidentate ligand). Find iron's oxidation state: 3 potassium give +3, and three oxalate ligands give 3 times (-2) = -6, so iron must be +3 to balance. The complex is negative, so iron is named ferrate. With three oxalato ligands we use tris (because oxalato already contains a multiplying prefix).
Name: potassium trioxalatoferrate(III) (also written potassium tris(oxalato)ferrate(III)).

Answer:
(i) Diamminesilver(I) dicyanidoargentate(I)
(ii) Potassium trioxalatoferrate(III)