Two novel derivatives of ammonia borane for hydrogen storage: synthesis, structure, and hydrogen desorption investigation

Two new derivatives of ammonia borane (AB), 1,2/1,3-di-aminopropane borane (1,2/1,3-TMDAB), were prepared through the coordination reaction between 1,2/1,3-di-aminopropane and BH3–THF, which were then characterized by HR-XRD, FT-IR, 13C and 11B NMR. The crystal structure of 1,3-TMDAB was obtained with a combined technique of HR-XRD data and DFT calculations. 1,3-TMDAB crystallizes in the space group of P212121 (no. 19) with an orthorhombic crystal system and lattice constants of a = 12.6439(8) Å, b = 8.6289(3) Å, c = 7.2322(2) Å, and V = 789.05(3) Å3. Both samples, with a theoretical hydrogen content of 9.8 wt%, were shown to release pure H2 during thermal dehydrogenation, presenting great advantages over AB which releases large amounts of impurities (such as NH3, B2H6 or borazine). Moreover, 1,2/1,3-TMDAB did not foam and showed a faster dehydrogenation rate compared with AB. Our newly synthesized 1,2/1,3-TMDAB may serve as a superior alternative to AB for hydrogen storage and enrich the research field of B–N–H hydrogen storage materials.