A little bit of lithium does a lot for hydrogen.

From detailed assessments of electronic structure, we find that a combination of significantly quantal elements, six of seven atoms being hydrogen, becomes a stable metal at a pressure approximately 1/4 of that required to metalize pure hydrogen itself. The system, LiH(6) (and other LiH(n)), may well have extensions beyond the constituent lithium. These hypothetical materials demonstrate that nontraditional stoichiometries can considerably expand the view of chemical combination under moderate pressure.