Thermal analysis of lanthanide(III) and Y(III) complexes with 4-hydroxy-3-methoxybenzoic acid

Summary

The complexes of lanthanides(III) and Y(III) with 4-hydroxy-3-methoxybenzoic acid (vanillic acid) of the formula Ln(C₈H₇O₄)₃×nH₂O where n=2 for La(III), Pr(III); n=3 for Nd(III); n=4 for Sm(III); n=5 for Ce(III) and n=6 for Eu(III), Gd(III), Tb(III), Dy(III), Ho(III), Er(III), Tm(III), Yb(III), Lu(III) and Y(III) were prepared and IR spectra and X-ray diffraction patterns and their thermal decomposition were investigated. The carboxylate group in the studied complexes is a bidentate chelating or a bidentate chelating and bridging ligand. They are crystalline compounds. When heated, the complexes lose their crystallization water and decompose to the oxides Ln₂O₃, CeO₂, Pr₆O₁₁ and Tb₄O₇. The intermediate decomposition products of complexes of La(III) to Lu(III) (except Ce(III)) are oxocarbonates Ln₂O₂CO₃.