Tetraaminecopper(II) persulphate
From Sciencemadness Wiki
Tetraammine Copper(II) persulphate (TACPs) is a very weak primary explosive with a very short shelf life.
Production
If solutions of ammonium persulphate and tetraammine copper sulfate are cooled and then mixed, bright purple crystals of the TACPs will settle out. These should be filtered and dried as quickly as possible, as the solid will completely break down into a unknown green solid with no energetic properties in a few hours.
This decomposition may be a reaction with water but is more likely to be a loss of ammonia from the structure.