The conditions and products of thermal decomposition of thorium(IV) complexes with general formula Th(R-C6H4COO)4 (whereR=2-CH3, 3-CH3, 4-CH3), Th(OH)2(4-CH3C6H4COO)2. H2O and Th(OH)2(R-C6H4COO)2·nH2O (whereR=2-COO, 3-COO,n=2;R=4-COO,n=1) were studied. Anhydrous thorium(IV) complexes decompose in two steps. On heating, tetra(2-methylbenzoato)-thorium(IV)
decomposes to yield ThO2 through the intermediate ThOCO3 whereas tetra(3-methylbenzoato)thorium(IV) and tetra(4-methylbenzoato)thorium(IV) decompose to ThO2 through oxocomplexes. Hydrated thorium(IV) complexes are dehydrated in one step and then anhydrous complexes decompose to
ThO2. Di [1,2-(benzene)dicarboxylato]dihydroxythorium(IV) decomposes directly to ThO2, whereas the 1,3- and 1,4-isomers through the intermediate thorium(IV) oxocarbonates.