Thermal and spectroscopic analysis of Co(II)–Fe(III) polyglyoxylate obtained through the reaction of ethylene glycol with metal nitrates

Abstract

The synthesis and thermal and spectroscopic studies of a new CoII–FeIII heteropolynuclear coordination compound are presented. The in situ oxidation product of ethylene glycol plays the role of ligand. Under specific working conditions, the reaction of ethylene glycol with FeIII and CoII nitrates in dilute acid solutions occurs with the oxidation of the former to glyoxylic acid, coordinated to the CoII and FeIII cations as glyoxylate anion (C2H2O4 2−), with simultaneous isolation of the heteropolynuclear coordination compound. In order to separate and identify the ligand, the synthesized coordination compound, having the composition formula Co4Fe10(L)9(OH)20(H2O)32·14H2O, where L is the glyoxylate anion, has been treated with R–H cationite (Purolite C-100). After the retention of the metal cations, the resulting glyoxylic acid was confirmed by measuring its physical constants, by specific reactions and through spectroscopic methods. The synthesized coordination compound was characterized by physical–chemical analysis, electronic spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffractometry (XRD) and thermal analysis. Cobalt ferrite impurified with ferric oxide was obtained following the thermal decomposition of CoII–FeIII polyhydroxoglyoxylate. The oxides obtained through thermolysis were studied by FTIR, XRD, scanning electron microscopy (SEM) and elemental analysis.