Dysprosium(II) bromide, also known as dysprosium dibromide, is an inorganic compound of dysprosium and bromine with the chemical formula DyBr2. It is one of the comparatively few binary lanthanide halides in which the lanthanide occurs in the +2 oxidation state.
Preparation Dysprosium(II) bromide can be prepared by reduction of dysprosium(III) bromide with elemental dysprosium under vacuum at about 800–900 °C:
Dy + 2 DyBr3 → 3 DyBr2
It can also be obtained by metallothermic reduction of DyBr3 with an alkali metal under high-temperature conditions. Reduction with sodium has been reported to give DyBr2, whereas heavier alkali metals tend to form ternary bromides instead.
Properties Dysprosium(II) bromide is a black, highly hygroscopic crystalline solid. It must be handled under rigorously dry inert gas or in high vacuum. On exposure to moist air it forms hydrated material which is unstable and gradually converts into oxybromides with evolution of hydrogen; the reaction proceeds much more rapidly in liquid water.
DyBr2 is a salt-like divalent rare-earth halide rather than a metallic subhalide. It adopts the strontium iodide structure type, in which Dy2+ is seven-coordinate by bromide ions. The structure is orthorhombic; modern crystallographic databases index DyBr2 in space group Pbca (No. 61).
Dysprosium(II) bromide belongs to the same structural family as the dibromides of thulium and ytterbium, which also adopt the SrI2-type structure.
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