Osmium heptafluoride

Osmium heptafluoride is a possible inorganic chemical compound of osmium metal and fluorine with the chemical formula. It was first reported in 1966 by the reaction of fluorine and osmium at 600 °C and 400 atm, but no purported synthesis could be reproduced in 2006, giving only osmium hexafluoride instead.

Physical properties
If it exists, osmium(VII) fluoride is supposedly a bluish-yellow hygroscopic substance, extremely unstable. The compound starts decomposing at –100 °C. It should be stored in a nickel vessel at the temperature of liquid nitrogen.

Chemical properties
Osmium heptafluoride decomposes to osmium hexafluoride when slightly heated:
 * 2OsF7 -> 2OsF6 + F2