Rubidium superoxide, rubidio superoxide or rubidium hyperoxide is a chemical compound with the chemical formula . Rubidium forms superoxide under certain conditions like direct contact with oxygen. In terms of oxidation states, the negatively charged superoxide and positively charged rubidium give it a structural formula of .
is stable in dry air, but is extremely hygroscopic. Between 280 and 360 ðC, rubidium superoxide will decompose, leaving not rubidium sesquioxide (), but rather rubidium peroxide ().
The compound has been studied as an example of magnetism arising intrinsically from the p-shell. has been predicted to be a paramagnetic Mott insulator. At low temperatures, it transitions to antiferromagnetic order, with a Neel temperature of 15 K.
Roughly speaking, has a crystal structure similar to tetragonal calcium carbide, but is rather distorted due to the JahnâÂÂTeller effect, which makes the crystal structure less symmetrical.
Rubidium superoxide can be created by slowly exposing elemental rubidium to oxygen gas:
Like other alkali metal hyperoxides, crystals can also be grown in liquid ammonia.
An even more oxygen rich compound, that of rubidium ozonide () can be created by reacting with ozone.