Cupric tetramminosulphate. I. Thermal decomposition

Abstract

A completely anhydrous sample of cupric tetramminesulphate has been prepared. T h e product previously reported to be anhydrous was found to contain up to 4 ' k of moisture on keeping over calcium chloride. Thermal decomposition of the slightly hydrated, as well as the completely anhydrous compounds, was followed in a closed apparatus at atmospheric pressure and/or in a vacuum. T w o molecules of ammonia were reversibly liberated on two successive steps. In a vacuum, the completely anhydrous, deep violetblue Cu(NH,),SO, lost one ammonia molecule a t 30" and a second molecule at 55". giving the pale blue Cu(NH,),SO,. A t temperatures above -90". irreversible decomposition of the diammine occurs with the gradual formation of a dark-grey to brown product, accompanied by sublimation of animonium sulphate.*