Nitratoauric acid

Nitratoauric acid, hydrogen tetranitratoaurate, or simply called gold(III) nitrate is a crystalline gold compound that forms the trihydrate, HAu(NO3)4*3H2O or more correctly H5O2Au(NO3)4*H2O. This compound is an intermediate in the process of extracting gold. In older literature it is also known as aurinitric acid.

Preparation and reactions
Nitratoauric acid is prepared by the reaction of gold(III) hydroxide and concentrated nitric acid at 100 °C:
 * Au(OH)3 + 4HNO3 -> HAu(NO3)4 + 3 H2O

This compound reacts with potassium nitrate to form potassium tetranitratoaurate at 0 °C:
 * HAu(NO3)4 + KNO3 -> KAu(NO3)4 + HNO3

Properties
Nitratoauric acid trihydrate decomposes to the monohydrate at 72 °C. If continually heated to 203 °C, it decomposes to auric oxide.

Simple gold(III) nitrate
The production of the simple nitrate (Au(NO3)3) was reported from the reaction of gold oxide and dinitrogen pentoxide, however, this was later proven to be nitronium tetranitratoaurate ((NO2)Au(NO3)4).

However, the ammine complex of the simple gold nitrate is known. Au(NH3)4(NO3)3, also known as tetraaminegold(III) nitrate, is produced by the addition of ammonium nitrate to a solution of chloroauric acid. The hydrolysis of this compound produces fulminating gold.