Hydride telluride

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

Formation
Salt-like hydride tellurides may be formed by heating tellurium with a metal hydride in an oxygen-free capsule at around 700°C with a caesium chloride flux to assist in crystal formation. For rare earth elements, this method works as long as tellurium has enough oxidising power to convert a +2 oxidation state to a +3 state. So for samarium, europium, thulium and ytterbium it does not work as the monotelluride is more stable with the metal in a +2 oxidation state. Also scandium and lutetium atoms are too small.


 * LaH3 + Te → LaHTe + H2

Tellurido-hydrido-transition metal complexes are known. They are formed by heating metal hydrido complexes with tellurium.


 * L2MH3 + 2 Te → L2M(Te2)H + H2
 * L2MH3 + Te → L2M(=Te)H + H2

where L and M represent ...

Properties
With rare earth elements the hydride tellurides all have the same structure as the small or heavy rare-earth elements. Six selenium ions are arranged in a trigonal prism around the rare-earth atom. The rectangular faces are capped with hydride ions. Bond lengths are about the same as for binary tellurides and hydrides.

When heated to 1100°C, rare-earth hydride tellurides decompose to a monotelluride: "2LaHTe → 2LaTe + H2"