Expanding the hydride chemistry: antiperovskites AMOH (A = Rb, Cs; M = Mo, W) introducing the transition oxometalate hydrides.

The four compounds AMOH (A = Rb, Cs; M = Mo, W) are introduced as the first members of the new material class of the transition oxometalate hydrides. The compounds are accessible a thermal synthesis route with carefully controlled conditions. Their crystal structures were solved by neutron diffraction of the deuterated analogues. RbMoOD, CsMoOD and CsWOD crystallize in the antiperovskite-like KSOF-structure type, while RbWOD adopts a different orthorhombic structure. H MAS NMR, Raman spectroscopy and elemental analysis prove the abundance of hydride ions next to oxometalate ions and experimental findings are supported by quantum chemical calculations. The tetragonal phases are direct and wide band gap semiconductors arising from hydride states, whereas RbWOH shows a unique, peculiar valence band structure dominated by hydride states.