AcCl3

AcCl3, or actinium trichloride, is an inorganic compound with the formula AcCl3. It consists of actinium in the +3 oxidation state coordinated to chloride ligands, forming a salt that is typical of actinide chlorides. In the solid state, it is a crystalline material; in aqueous media it hydrolyzes readily to form aqua- and oxychloride species. The compound is usually prepared and stored under controlled conditions in specialized laboratories due to the radiological nature of actinium.

Preparation and properties

Actinium trichloride can be produced by chlorinating actinium-containing solids, such as actinium oxide, with chlorine gas at elevated temperatures, or by reacting actinium salts with hydrogen chloride. In solution, AcCl3 forms various hydrated and complexed species and behaves as a strong Lewis acid, coordinating with chloride and water molecules. Its chemistry is similar in many respects to other trivalent actinide chlorides, with sensitivity to moisture and oxidation state.

Applications

Because all actinium compounds are radioactive, AcCl3 has limited commercial use. It serves primarily as a radiochemical reagent and as a precursor for synthesizing other actinium compounds, including those investigated for radiopharmaceutical applications. In particular, actinium-225–based compounds are studied for targeted alpha therapy, where AcCl3 can act as a starting material for producing more complex actinium-containing radiopharmaceuticals.

Safety

Actinium compounds are highly radioactive alpha emitters. Handling AcCl3 requires licensed radiochemical facilities, appropriate shielding, containment, and strict radiological monitoring. Long-lived isotopes contribute to ongoing radiological hazards, and disposal is tightly regulated.