Hydrothermal synthesis and characterization of lanthanide oxalates: <i style="">In situ</i> oxalate formation from tartaric acid in presence of KI

Abstract

Two new three-dimensional lanthanide oxalates [Pr₂(C₂O₄)₃(H₂O)₄]·2H₂O (<b style="">1</b>) and [Nd₂(C₂O₄)₃(H₂O)₄]·2H₂O (<b style="">2</b>) and a two-dimensional oxalate [Pr₂(C₂O₄)₃(H₂O)₆]·3H₂O (<b style="">3</b>) have been prepared by hydrothermal process and characterized by single crystal X-ray analysis. Compound <b style="">(1)</b> crystallizes in monoclinic crystal system with <i style="">P</i>2₁/c space group whereas <b style="">(2)</b> crystallizes in triclinic crystal system with <i style="">P</i>ī space group. Although Pr and Nd are twin lanthanides, they have produced different crystal structures under the same reaction conditions. Compound <b style="">(3)</b> is produced by the <i>in situ</i> hydrothermal degradation of tartaric acid to oxalate ions in presence of KI. In this reaction, the iodide anion instead of metal cation, acts as the reducing agent during the degradation of tartaric acid to oxalate. Thermogravimetric, elemental analysis and IR studies have also been carried out for these compounds.