THERMAL BEHAVIOR OF DOUBLE COMPLEXES [Co(NH3)6][Fe(CN)6] AND [CO(en)3][Fe(CN)6]·2H2O

Abstract

Thermal behavior of double complex compounds (DCC) of first transition metal row has been studied on the example of [СоA6][Fe(CN)6] (A = NH3, C2H8N2/2) in oxidative(air), inert(argon, nitrogen, helium) and reductive(hydrogen) atmospheres. The analysis of solid and gaseous thermolysis products has been performed for separate temperature ranges. The TG curves of the thermolysis first stage coincide with each other for all the investigated atmospheres up to approximately 300 °C. DCC [Со(NH3)6][Fe(CN)6] (I) and [Со(en)3][Fe(CN)6] (II) undergo to first stage of thermal decomposition with the removal of the part of neutral ligands and 1-2, but not more as 3 CN groups in temperature range of 160-300 and 200-350°С in oxidative and 160-400 and 210-550 °С, in inert medium, respectively. DCC I forms the intermediate [(NH3)2CoFeC4N3], [(NH3)2.6CoFe(CN)5] and [(NH3)3CoFe(CN)4.3] at 330, 350 и 430 °С in atmosphere of air, argon and hydrogen. For DCC II the intermediates are not registered. At temperatures above 300 °C the TG curves diverge and relate already to the interaction of thermolysis products with the gaseous medium. The thermolysis in argon and hydrogen is accompanied by partial reduction of ligands and central atoms of DCCs, thermolysis in the air atmosphere - complete oxidation of ligands and central ions. The thermal behavior of DCC is compared with the thermal behavior of 3d metals cationic complexes on base of literature data. The thermolysis of all the DCC and cation complexes discussed here proceeds with the removal of neutral ligands in the temperature range of 50-400 °C. For citation:Pechenyuk S.I., Domonov D.P., Gosteva A.N., Semushina Yu.P., Shimkin A.A. Thermal behavior of double complexes [Co(NH3)6][Fe(CN)6] and [Co(en)3][Fe(CN)6]·2H2O. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 4-5. P. 49-56