Ammonia-Borane and Related Compounds as Dihydrogen Sources

Studies conducted in the subject of ammonia-borane and related compounds as dihydrogen sources are presented. The phase transitions of ammonia-borane studied at increased pressures and at various temperatures by powder X-ray diffraction show change of its crystal lattice. The inelastic incoherent neutron scattering (IINS) spectra of ammonia-borane shows an improved assignment of low frequency torsional motions. Studies have also found that the head to tail dimer of ammonia-borane exhibit dihydrogen bonds. The nonvolatile white residue of the first decomposition step of ammonia-borane is described as polyaminoborane (PAB) of the composition BNH4 and is likely to contain borazinyl residues, cyclic, and cross-linked structures. Additives such as lithium imide and lithium nitride used for the release of hydrogen from ammonia-borane in solution showed release of ammonia gas.