Oxidehydrides

Oxidehydrides are a class of inorganic compounds that contain both oxide (O2−) and hydride (H−) anions within a single crystalline framework. Often described as oxyhydrides or mixed-anion oxides, they can be viewed as oxide lattices into which hydride ions have been inserted or substituted. The resulting materials are typically metal-rich and exhibit properties distinct from simple oxides or hydrides because of the simultaneous presence of two different anion types.

In oxidehydrides, oxide and hydride ions occupy distinct lattice sites and interact with a network of metal cations. The hydride ions can act as electron donors and can form M–H bonds, influencing electronic, optical, and magnetic properties. Because hydrogen positions are light, neutron diffraction and vibrational spectroscopy (IR, Raman) are common tools to characterize them, alongside X-ray diffraction for overall structure.

Synthesis generally requires high-temperature hydrogenation of precursors or metathesis-type reactions using hydride sources under reducing conditions. General formulae are written as MxOyHz, with the oxide content y and hydride content z balancing charge and framework. Reported oxidehydrides span various metals, including transition and rare-earth elements, and often adopt fluorite-like, perovskite-related, or layered structures.

Potential applications and interest center on their mixed-anion chemistry, which can yield unconventional electronic behavior, proton conductivity, hydrogen storage potential, and catalytic activity. The field remains active, with ongoing efforts to stabilize, characterize, and understand the relationships between composition, structure, and properties in oxidehydrides.