Editing Actinium (section)

===Halides===
[[Actinium trifluoride]] can be produced either in solution or in solid reaction. The former reaction is carried out at room temperature, by adding [[hydrofluoric acid]] to a solution containing actinium ions. In the latter method, actinium metal is treated with hydrogen fluoride vapors at {{cvt|700|°C}} in an all-platinum setup. Treating actinium trifluoride with [[ammonium hydroxide]] at {{cvt|900|–|1000|°C}} yields [[oxyfluoride]] AcOF. Whereas lanthanum oxyfluoride can be easily obtained by burning lanthanum trifluoride in air at {{cvt|800|°C}} for an hour, similar treatment of actinium trifluoride yields no AcOF and only results in melting of the initial product.<ref name="j2" /><ref name="m87">Meyer, pp. 87–88</ref>

:AcF<sub>3</sub> + 2 NH<sub>3</sub> + H<sub>2</sub>O → AcOF + 2 NH<sub>4</sub>F

Actinium trichloride is obtained by reacting actinium hydroxide or [[oxalate]] with [[carbon tetrachloride]] vapors at temperatures above {{cvt|960|°C}}. Similarly to the oxyfluoride, actinium [[oxychloride]] can be prepared by hydrolyzing actinium trichloride with [[ammonium hydroxide]] at {{cvt|1000|°C}}. However, in contrast to the oxyfluoride, the oxychloride could well be synthesized by igniting a solution of actinium trichloride in [[hydrochloric acid]] with [[ammonia]].<ref name="j2" />

Reaction of [[aluminium bromide]] and actinium oxide yields [[Actinium(III) bromide|actinium tribromide]]:
:Ac<sub>2</sub>O<sub>3</sub> + 2 AlBr<sub>3</sub> → 2 AcBr<sub>3</sub> + Al<sub>2</sub>O<sub>3</sub>

and treating it with ammonium hydroxide at {{cvt|500|°C}} results in the oxybromide AcOBr.<ref name="j2" />