New complexes of rare earth elements with methylsuccinic acid

The rare earth element methylsuccinates were prepared as crystalline solids with general formula Ln2(C5H8O4)3·nH2O, where n = 8 for Ce-Nd and Tb, n = 7 for Sm, n = 6 for Y and La, n= 5 for Dy-Tm, n = 4 for Eu,Yb and n = 3 for Gd. The IR spectra of the complexes prepared were recorded and their solubility in water at 293 K and thermal decomposition in air atmosphere were investigated. During heating the complexes lose crystallization water in one (La, Nd-Gd, Tm-Tu) or two steps (Eu, Dy, Ho, Er) going over to monohydrates (Y, Ce, Tb) or anhydrous compounds (La, Pr-Gd, Dy-Lu) and then the complexes decompose directly to oxides (Ce, Pr, Tb-Er) or with intermediate formation of oxocarbonates Ln2O2CO3 (La, Nd-Gd) or Ln2O(CO3)2 (Y, Tm-Lu). The carboxylate groups in the complexes prepared act probably as bidentate chelating. (author)