Hydrogen Release Studies of Alkali Metal Amidoboranes

Journal Article · Mon Apr 19 04:00:00 EDT 2010 · Inorganic Chemistry, 49(8):3905-3910

DOI:https://doi.org/10.1021/ic100119m· OSTI ID:982297

Luedtke, Avery T; Autrey, Thomas

A series of metal amido boranes LiNH2BH3 (LAB), NaNH2BH3 (SAB), LiNH(Me)BH3 (LMAB), NaNH(Me)BH3 (SMAB), KNH(Me)BH3 (PMAB), and KNH(tBu)BH3 (PBAB) were synthesized, by solution phase methods, and the thermal release of H2 in the solid state was studied. Based on the observed trends in reaction rates of H > Me > tBu and the kinetic isotope effect, the mechanism of hydrogen release from MAB compounds was found to proceed through a bimolecular mechanism involving the intermediacy of a MH (M = Li, Na, or K). The mechanism of hydrogen release from metal amidoboranes, a metal ion assisted hydride transfer, is very different than the mechanism of hydrogen release from the parent compound ammonia borane (AB). The non-volatile products formed from MAB’s are significantly different than the products formed after hydrogen release from AB. The boron containing resulting from the release of one equivalent of hydrogen from the metal amidoboranes were characterized by MAS 11B NMR spectroscopy and found to contain both BH3 and sp2 hybridized BH groups, consistent with a general structural feature MN(R)=BHN(R)MBH3. This work was funded by the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy as part of the Chemical Hydrogen Storage CoE at Pacific Northwest National Laboratory (PNNL). PNNL is operated for the U.S. DOE by Battelle. MAS NMR studies were performed using EMSL, a national scientific user facility sponsored by the Department of Energy’s Office of Biological and Environmental Research located at PNNL.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 982297
• Report Number(s): PNNL-SA-71061; 25661; EB4202000
• Journal Information: Inorganic Chemistry, 49(8):3905-3910, Journal Name: Inorganic Chemistry, 49(8):3905-3910 Journal Issue: 8 Vol. 49; ISSN 0020-1669; ISSN 1520-510X
• Country of Publication: United States
• Language: English

Related Subjects

08 HYDROGEN
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
59 BASIC BIOLOGICAL SCIENCES
99 GENERAL AND MISCELLANEOUS
ALKALI METALS
AMMONIA
BORANES
BORON
ENERGY
ENERGY EFFICIENCY
Energy Storage
Environmental Molecular Sciences Laboratory
HYDRIDES
HYDROGEN
HYDROGEN STORAGE
IONS
ISOTOPE EFFECTS
KINETICS
METALS
Metal Amidoborane
Metal Ion Assisted Hydride Transfer
NUCLEAR MAGNETIC RESONANCE
REACTION KINETICS
SOLIDS
SOLUTIONS
SPECTROSCOPY
Solid State Kinetics
WORK