Thorium Acetylacetone, Th(C₅H₇O₂)₄

In common with other rare earth metals, thorium forms a solid compound with acetylacetone - Thorium Acetylacetone, Th(C₅H₇O₂)₄. It is obtained by the action of acetylacetone on thorium hydroxide, of sodium acetylacetone on thorium salts, or in nearly quantitative yield by adding a solution of a thorium salt to a faintly alkaline solution of acetylacetone, and precipitating with the smallest quantity of ammonia. The product can be crystallised from alcohol, melts at 171° C., and may be sublimed under reduced pressure without appreciable decomposition; its molecular weight in carbon tetrachloride solution confirms the formula Th(C₅H₇O₂)₄. With ammonia it forms the addition compound [Th(C₅H₇O₂)₄]₂.NH₃. The stereochemical constitution of thorium and other metallic acetylacetones presents an interesting problem.