Preparation and Thermal Analysis of Cobalt(III) Complex with Quadridentate Dioxime

Abstract

Electrolyte cobalt (III) complexes with quadridentate dioxime, formulated as [Co(Hbhen)B₂]Cl₂ or [Co(Hbhpn)B₂]Cl₂ were isolated, where dioxime ligand H₂bhen was N, N'-bis(2-hydroxyimino-1-methylpropylidene) ethylenediamine and H₂bhpn was N, N'-bis(2-hydroxyimi-no-1-methylpropylidene)-1, 3-propanediamine, while B was aniline or its derivatives, and X was Cl-, Br-, or I- ion. Thermal decomposition of these complexes was also studied in the solid state by thermogravimetry (TG) and differential thermal analysis (DTA).
An endothermic phenomenon was observed at the first stage of therma l decomposition of these complexes. The analytical studies on the infrared and electronic spectra of therma l decomposition products revealed that the endothermic phenomenon was due to the replac ement of axial ligand (base B) by the outer-sphere anion. It was found that a new green compound was formed as the replacement product at the first thermal decomposition of [Co(Hbhpn)B₂]X₂complex. The electronic, infrared, and X-ray photoelectron spectra of the green compound suggest that the constitutional formula is [CoX₂(Hbhpn)].