TbCl3

Terbium trichloride, TbCl3, is a halide compound of the lanthanide terbium. It exists as an anhydrous salt and as hydrates; the hexahydrate TbCl3·6H2O is common when prepared or used in aqueous media. The anhydrous form is highly hygroscopic and rapidly hydrolyzes in moist air, forming terbium oxychloride species and hydrated forms.

Preparation and handling: TbCl3 can be prepared by reacting terbium oxide or hydroxide with hydrochloric acid: Tb2O3 + 6 HCl → 2 TbCl3 + 3 H2O. It can also be produced by direct chlorination of terbium metal: 2 Tb + 3 Cl2 → 2 TbCl3. In solution, Tb3+ forms aqua complexes, and in the presence of chloride, various chloro complexes can form. The compound is typically handled under dry conditions or in dry solvents due to its moisture sensitivity.

Properties: TbCl3 is a white to colorless solid that dissolves in water to give acidic chloride solutions. The anhydrous salt is moisture sensitive and can release hydrochloric acid upon hydrolysis. It readily forms coordination complexes with ligands such as water, amines, and phosphines, reflecting the Lewis acidic character of Tb3+ in this system.

Applications: TbCl3 serves as a convenient source of terbium(III) ions for the synthesis of coordination compounds and for preparing terbium-doped phosphors and materials used in displays and lighting. It is employed in research as a precursor for terbium-containing compounds and in various synthesis routes requiring Tb3+.

Safety: TbCl3 is corrosive and can irritate skin and eyes. Solutions are acidic and can release HCl upon hydrolysis. It should be handled with appropriate personal protective equipment, and dry conditions or inert atmospheres are recommended to avoid hydrolysis.