Yttrium(III) chloride
Yttrium(III) chloride is an inorganic compound of yttrium and chloride. It exists in two forms, the hydrate (YCl(HO)) and an anhydrous form (YCl). Both are colourless solids that are highly soluble in water and deliquescent. Structure. Solid YCl adopts a cubic structure with close-packed chloride ions and yttrium ions filling one third of the octahedral holes and the resulting YCl octahedra sharing three edges with adjacent octahedra, giving it a layered structure. This structure is shared by a range of compounds, notably AlCl. Preparation and reactions. YCl is often prepared by the "ammonium chloride route," starting from  either YO or hydrated chloride or oxychloride. or YCl·6HO. These methods produce (NH)[YCl]: The pentachloride decomposes thermally according to the following equation: The thermolysis reaction proceeds via the intermediacy of (NH)[YCl]. Treating YO with aqueous HCl produces the hydrated chloride (YCl·6HO). When heated, this salt yields yttrium oxychloride rather than reverting to the anhydrous form.