Iron(I) hydride

Iron(I) hydride is a chemical compound of iron and hydrogen with chemical formula FeH. It has been detected in isolation only in extreme environments, like trapped in frozen noble gases, in the atmosphere of cool stars, or as a gas at temperatures above the boiling point of iron. It is assumed to have three dangling valence bonds, and is therefore a free radical; its formula may be written FeH to emphasize this fact.