Catalytic Effects of Ruthenocene Bimetallic Compounds Derived from Fused Aromatic Ring Ligands on the Main Oxidizing Agent for Solid Rocket Motor

We report the catalytic effect of three ruthenocene bimetallic compounds derived from fused aromatic rings of general formula [{Cp*Ru}₂L], with Cp*: pentamethylcyclopentadiene and L = pentalene (1), 2,6-diethyl-4,8-dimethyl-s-indacene (2), and 2,7-diethyl-as-indacene (3), on the thermal decomposition of ammonium perchlorate (AP). The new compound 3 was characterized by a combination of multinuclear magnetic resonance (NMR) spectroscopy and elemental analysis. The differential scanning calorimetry (DSC) analysis of compound 3 shows a decrease in the decomposition temperature of AP to 347 ºC, increases the energy release to 2048 J g^-1 and, consequently, leads to the lowest activation energy (42.9 kJ mol^-1). These results are comparable to the typically used metallocene (catocene: 347 ºC and 2472 J g^-1), suggesting a suitable and competitive alternative to be used as a modifier for composite solid propellants.

Keywords:
thermal decomposition; burning rate; catalysis