Mono- and Dinuclear Ferrocenyl Ionic Compounds with Polycyano Anions. Characterization, Migration, and Catalytic Effects on Thermal Decomposition of Energetic Compounds

Neutral ferrocene-based burning rate (BR) catalysts show strong migration trends and volatility during long-time storage and curing of the composite solid propellants. To reduce these disadvantages thirty-two ferrocenyl quaternary ammonium compounds, paired with polycyano anions, were synthesized and characterized by H-1 NMR, C-13 NMR, and UV/Vis spectroscopy, as well as elemental analysis. Additionally, crystal structures of eight compounds were confirmed by single-crystal X-ray diffraction. TG and DSC analyses indicated that the compounds containing 1,1,2,3,3-pentacyanopropenide anions show high thermal stability. Cyclic voltammetry studies suggested that they are quasi-reversible or irreversible redox systems. Anti-migration tests verified that the tested compounds show very low migration tendency and some of them exhibit no migration after 30 days aging at 70 degrees C. Their catalytic efficiency in the thermal decomposition of ammonium perchlorate (AP), 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX), and 1,2,5,7-tetranitro-1,3,5,7-tetraazacyclooctane (HMX) were examined by DSC analyses. The results revealed that most of the compounds exhibit distinct effects on the thermal degradation of AP and RDX. Two compounds have good catalytic ability in the thermal decomposition of HMX, representing rare examples of the reported ferrocenyl ionic compounds, which display catalytic property during combustion of HMX.