Synthesis and Dehydrogenation of Organic Salts of a Five-Membered B/N Anionic Chain,a Novel Ionic Liquid

We have synthesized the tetrabutylammonium (Bu₄N]⁺), tetraethylammonium (Et₄N]⁺), guanidinium (C(NH₂)₃]⁺), and methylguanidinium (C(N₃H₅CH₃)]⁺) salts of the BH₃(NH₂BH₂)₂H]⁻ anion, a five-membered B/N anionic chain, in high yields by the metathesis reactions of NaBH₃(NH₂BH₂)₂H] with the corresponding halides and characterized them by NMR (¹¹B, ¹¹B{¹H}, ¹H, ¹H{¹¹B}, ¹³C), IR, elemental analysis, TGA-DSC, and TGA-MS. These complexes behave like ionic liquids (ILs), in which the melting point of the Bu₄N]BH₃(NH₂BH₂)₂H] is the lowest (−51 °C). The dehydrogenation of these ILs have been studied through the thermal decomposition and catalytic hydrolysis in aqueous solution using the noble or non-noble metals or their salts as catalysts, and the results indicate that these ILs of five-membered B/N anionic chain are promising hydrogen storage materials.