Hydride selenide

Hydride selenides are mixed anion compounds containing both hydride and selenide ions. They are in the category of heteroanionic chalcogenides, or mixed anion compounds. Related compounds include the oxyhydrides, hydride sulfides, and hydride tellurides.

Formation
Salt-like hydride selenides may be formed by heating selenium with a metal hydride in an oxygen-free capsule. For rare earth elements, this method works as long as selenium has enough oxidising power to convert a +2 oxidation state to a +3 state. So for europium and ytterbium it does not work as the monoselenide is more stable.

One transition metal complex was formed from a lithium zirconium hydride complex in solution reacting with diphenylphosphine selenide.

Properties
With rare earth elements there are two structure depending on the size of the metal ions. The large atoms form a 2H hexagonal anti-nickel arsenide structure, with hydrogen inserted into tetrahedral positions. A 1H hexagonal structure is found in rare earth elements from gadolinium to lutetium, and yttrium.