Question

Write formula of sodium dicyanoaurate(I) complex.

Answer 1

To solve this we must know that the central metal in the sodium dicyanoaurate(I) complex is aurum $\left( {{\text{Au}}} \right)$. The ligand is cyano. The (I) indicates that there is one positive charge on the dicyanoaurate ion.

Complete solution:
We are given the complex sodium dicyanoaurate(I).
The ligand is cyano. dicyano indicates that there are two cyanide ligands. The chemical formula for cyanide ligand is ${\text{CN}}$.
aurate indicates that the central metal ion is aurum. The chemical symbol for aurum is ${\text{Au}}$.
Thus, we write dicyanoaurate(I) in the square parentheses. Thus, $[{\text{Au(CN}}{{\text{)}}_2}]$.
sodium indicates that sodium ligand is outside the first coordination sphere. Thus, we write sodium outside the parentheses. Thus, ${\text{Na}}[{\text{Au(CN}}{{\text{)}}_2}]$.

Thus, the formula of sodium dicyanoaurate(I) complex is ${\text{Na}}[{\text{Au(CN}}{{\text{)}}_2}]$.

Note: The rules for writing the IUPAC nomenclature of complexes are as follows:

1. Identify the ligand and name the ligand with the prefix mono-, di-, tri-, tetra-, etc. depending on the number of ligands.
2. Identify the central metal atom and write the name of the central metal atom ending with suffix –ate.
3. Determine the oxidation number of the central metal atom and write the charge in roman numeral in a bracket ( ) after writing the complete name.
4. The central metal is always written inside the square parentheses.
5. The ligands outside the second coordination sphere are written outside the square parentheses.