Aluminohydrides: Structures, NMR, solid-state reactions

Proton NMR studies of the NaAlH4 structure

“…The M 2 value for the 0°configuration is smaller than the experimentally observed second moment, which is an indication of structural differences between NaAlH 4 and its isotopic modification NaAlD 4 . It is interesting to note that previous investigations of the 23 Na and 27 Al quadrupole coupling constants also yielded different values for NaAlH 4 and NaAlD 4 [16]. On the other hand, the heteronuclear contribution M 2,hetero agrees within the experimental uncertainty with the measured value.…”

“…The first 1 H NMR investigations of hydrogen dynamics in the hexahydride Na 3 AlH 6 were performed in 1981 by Senegas et al [15]. Measurements of the 2 H, 23 Na, and 27 Al quadrupole coupling constants have been performed on NaAlH 4 and its isotopic modification NaAlD 4 [16]. The Ti-catalyzed thermal decomposition of LiAlH 4 has been studied by 27 Al magic angle spinning (MAS) NMR spectroscopy [17,18].…”

Molecular H2 trapped in AlH3 solid

“…In closing, we note that other hydrogen-storage materials (e.g., such as NaAlH 4 ) have been reported [8][9][10][11][12][13][14] to show similar sharp NMR peaks. While we suspect that trapped molecular H 2 may also be present in some of these materials, the peak could arise from residual solvents.…”

“…Indeed, Zogal et al reported such a feature in spectra produced by both continuous-wave [6] and pulsed [7] methods years ago, which they attributed to molecular hydrogen (H 2 ) adsorbed on surfaces of the hydride particles [7]. Similar narrow NMR components have been reported [8][9][10][11][12][13][14] in related hydrogen-storage systems such as NaAlH 4 .…”

Parametrization of a reactive force field for aluminum hydride

“…[48][49][50][51] The issue of hydrogen molecules being trapped in cages or channels of hydrogen storage media will present the next technological challenges with a view to fully harnessing the storage capabilities of these systems. Trapped molecular hydrogen implies that not all the desorbed hydrogen diffuses out during the thermal decomposition process of the potential hydrogen storage materials.…”