11/03/2008 · The aqua regia is a powerful solvent due to the combined effect of ions H +, NO3 , and Cl in solution ( The oxidation is favored by the complexing capacity of the ion Cl 2 ) . The three ions react with gold atoms, for example, to form water, and the stable nitric oxide ion aurico tetrachloride complex ( AuCl4 ), which remains in ...