Composition of the thorium(IV)-8-hydroxyquinoline adduct compound

The orange compound formed between thorium(IV) and 8-hydroxyquinoline by conventional precipitation is non-stoichiometric. The composition is very sensitive to experimental conditions; the average ratio of bound 8-hydroxyquinoline to thorium was found to be 4.9:1. The deficiency of 8-hydroxyquinoline is due either to partial hydrolysis of thorium, or to the presence of co-ordinated water. A simple procedure for the preparation of the pure tetrakis compound is described.