It decomps in H2O.
Dangerous stuff, toady played with Mn2)7 a bit as a kid. It appears as a dark, kinda oily looking liquid. Very, very powerful oxidant.And when it dets, it decomps into enough ozone gas to set fire to EtoH, dripped onto a substrate. It can be prepared as a solution in anhydrous CCl4 however, or in dichlor. Do NOT try distilling it though. The elder toad has been meaning to try playing about with it in soln. as an oxidant sometime.