Cobalt–Imidazole Complexes: Effect of Anion Nature on Thermochemical Properties

Abstract

A solvent-free method was proposed for the synthesis of hexaimidazolecobalt(II) nitrate and perchlorate complexes—[Co(C3H4N2)6](NO3)2 and [Co(C3H4N2)6](ClO4)2—by adding cobalt salts to melted imidazole. The composition, charge state of the metal, and the structure of the resulting complexes were confirmed by elemental analysis, XPS, IR spectroscopy, and XRD. The study of the thermochemical properties of the synthesized complexes showed that [Co(C3H4N2)6](NO3)2 and [Co(C3H4N2)6](ClO4)2 are thermally stable up to 150 and 170 °C, respectively. When the critical temperature of thermal decomposition is reached, oxidative two-stage gasification is observed. In this case, the organic component of the [Co(C3H4N2)6](NO3)2 complex undergoes almost complete gasification to form Co3O4 with a slight admixture of CoO, which makes it attractive as a component of gas-generation compositions, like airbags.

Keywords

• gas-generation composition
• cobalt complex
• solvent-free synthesis
• imidazole
• high-energy ligand
• oxidizing anion