4ReCl4 + 32KCN + O2 + H2O → 4K3[Re(CN)8] + 16KCl + 4KOH
Rhenium(IV) chloride react with potassium cyanide, oxygen and water to produce potassium oktacyanorhenate(V), potassium chloride and potassium hydroxide. Potassium cyanide - concentrated solution.