PtO2•4H2O + 4(NH3•H2O) → [Pt(NH3)4(OH)2](OH)2 + 6H2O
Platinum(IV) oxide tetrahydrate react with ammonium hydroxide to produce trance-dihydroxotetraammineplatinum(IV) hydroxide and water. Ammonium hydroxide - concentrated solution. The reaction takes place in a diluted solution sodium hydroxide.