Synthesis and study of mixed-ligand heterometallic complexes of cobalt and neodymium succinates with pyridine or phenanthroline

Abstract

The paper reports the results of the study on the synthesis of new heterometallic complexes of Co(II) and Nd(III) with succinic acid in the presence of 1,10-phenanthroline or pyridine. The following hetero- and monocomplexes were synthesized: [Со(С4Н4О4)2Ру]2H2O and [Со(С4Н4О4)Рhen]2H2O; [Nd2(С4Н4О4)3]5Н2О and [Nd2(С4Н4О4)32Phen]2Н2О; [Сo2Nd2(C4Н4O4)54Py]4Н2О and [Сo2Nd2(C4Н4O4)52Phen]4Н2О (Phen – phenanthroline, and Py – pyridine). The study of their composition, structure, thermal properties and determination of the ability of heterocomplexes to form complex oxides was carried out. The complexes were characterized by a number of physicochemical methods: elemental analysis, IR- and diffuse reflection spectroscopies, X-ray powder diffraction and differential thermal analysis. Based on the analysis of diffuse reflection spectra and IR spectra of heterocomplexes, it was shown that succinic acid and 1,10-phenanthroline are bidentately bound to metal atoms. The metals are connected by succinic acid, forming a chain. Oxide powders were obtained during thermolysis of heterocomplexes up to 8000C. The composition of the synthesized heterometallic compounds was controlled by X-ray powder diffraction. It was shown that a complex oxide of NdСоО3 (cubic crystal system), without impurities, was formed, when the heterocomplex of phenanthroline [Сo2Nd2(C4Н4O4)52Phen]4Н2О was heated to 8000C. When heating the heterocomplex of pyridine [Сo2Nd2(C4Н4O4)54Py]4Н2О, in addition to the complex oxide NdСоО3, oxides Nd2О3 (hexagonal crystal system), Nd2О3 (cubic crystal system) and Со3O4 oxide (cubic crystal system) were formed. The heterocomplex [Сo2Nd2(C4Н4O4)52Phen]4Н2О can be used as a precursor for the synthesis of cobaltate of neodymium with lower energy costs than in solid-phase synthesis.