Synthesis, crystal structure and properties of benzimidazole-bridged dinuclear ferrocenyl derivatives

1-Ferrocenyl methyl-2-ferrocenyl-3-methylbenzimidazolium iodide (3) and 1-ferrocenyl methyl-2-ferrocenyl-3-ethylbenzimidazolium iodide (4) have been synthesized and fully characterized by MS, IR, 1H NMR, 13C NMR and elemental analysis. The structure-property relationship was investigated based on single crystal X-ray diffraction analysis, UV–Vis spectroscopy, electrochemical measurements and density functional theory calculations (DFT). The mechanism of the electron transfer of 3 has been studied by DFT. Their catalytic effect on the thermal decomposition of ammonium perchlorate (AP) was investigated using differential scanning calorimetry (DSC) and thermogravimetry (TG). The results from DSC and TG analysis indicate that 3 and 4 are of high catalytic effect on lowering the decomposition temperature of AP. We expect that the novel benzimidazole-bridged dinuclear ferrocenyl derivatives would have great value in preparing high-burning-rate catalyst for composite solid propellants.