Solid state NMR study on the thermal decomposition pathway of sodium amidoborane NaNH2BH3

Shimoda, Kei; Zhang, Yu; Ichikawa, Takayuki; Miyaoka, Hiroki; Kojima, Yoshitsugu

doi:10.1039/c0jm02828b

Cited by 46 publications

(63 citation statements)

References 19 publications

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“…Thel atter two bands are similart ot hose observed upon thermald ecomposition of the pristineA Bw ith the formation of polymeric (NH x BH x ) n (1 x 2) species ( Figure S10 in the Supporting Information). [31,32] Furthermore, in resemblance to binary amidoboranes M(NH 2 BH 3 ) n (n = 1, M = Li + ,N a + ,K + ; n = 2, M = Ca 2 + ,M g 2 + ) [15,[34][35][36] and to the Li 3 AlH 6 -4 AB [25] system,w eo bserved the formation of amorphous product(s), most likely,o ft he hydrogen-poor Al-N-B-H composition(s). Interestingly,r ecent theoretical calculations of the decomposition mechanism of Al(NH 2 BH 3 ) 3 propose the formation of Al(NBH) 3 .…”

Section: Reactionp Athways Volumetric Analysis and Reversibility Testsmentioning

confidence: 99%

A Composite of Complex and Chemical Hydrides Yields the First Al‐Based Amidoborane with Improved Hydrogen Storage Properties

Dovgaliuk

Jepsen

Safin

et al. 2015

Chemistry A European J

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The first Al-based amidoborane Na[Al(NH2 BH3 )4 ] was obtained through a mechanochemical treatment of the NaAlH4 -4 AB (AB=NH3 BH3 ) composite releasing 4.5 wt % of pure hydrogen. The same amidoborane was also produced upon heating the composite at 70 °C. The crystal structure of Na[Al(NH2 BH3 )4 ], elucidated from synchrotron X-ray powder diffraction and confirmed by DFT calculations, contains the previously unknown tetrahedral ion [Al(NH2 BH3 )4 ](-) , with every NH2 BH3 (-) ligand coordinated to aluminum through nitrogen atoms. Combination of complex and chemical hydrides in the same compound was possible due to both the lower stability of the AlH bonds compared to the BH ones in borohydride, and due to the strong Lewis acidity of Al(3+) . According to the thermogravimetric analysis-differential scanning calorimetry-mass spectrometry (TGA-DSC-MS) studies, Na[Al(NH2 BH3 )4 ] releases in two steps 9 wt % of pure hydrogen. As a result of this decomposition, which was also supported by volumetric studies, the formation of NaBH4 and amorphous product(s) of the surmised composition AlN4 B3 H(0-3.6) were observed. Furthermore, volumetric experiments have also shown that the final residue can reversibly absorb about 27 % of the released hydrogen at 250 °C and p(H2 )=150 bar. Hydrogen re-absorption does not regenerate neither Na[Al(NH2 BH3 )4 ] nor starting materials, NaAlH4 and AB, but rather occurs within amorphous product(s). Detailed studies of the latter one(s) can open an avenue for a new family of reversible hydrogen storage materials. Finally, the NaAlH4 -4 AB composite might become a starting point towards a new series of aluminum-based tetraamidoboranes with improved hydrogen storage properties such as hydrogen storage density, hydrogen purity, and reversibility.

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Section: Reactionp Athways Volumetric Analysis and Reversibility Testsmentioning

confidence: 99%

A Composite of Complex and Chemical Hydrides Yields the First Al‐Based Amidoborane with Improved Hydrogen Storage Properties

Dovgaliuk

Jepsen

Safin

et al. 2015

Chemistry A European J

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“…A number of papers were published reporting alkali metal amidoboranes as sources of pure hydrogen, e.g., LiAB [18,19,86], NaAB [18,86] and KAB [25]. On the other hand, several other groups reported for these materials the desorption of hydrogen contaminated with ammonia: α-LiAB [20,25,39,89,90], β-LiAB [20] and NaAB [23,24,87,88,98]. Some amidoborane salts (KAB [25,89], Mg(AB) 2 [29], Al(AB) 3 [35], and LiAl(AB) 4 [35,40]) were reported to desorb pure hydrogen and, currently, there are no contradictory reports.…”

Section: Thermal Decomposition Of Metal Amidoboranesmentioning

confidence: 99%

“…In Figure 4, we have shown a collection of the 11 B NMR spectra, while, in Table 3, we have listed 11 B NMR chemical shifts and J-coupling constants for various amidoboranes present studied so far. Two papers have reported "non-standard" NMR spectra of amidoborane salts; Shimoda et al studied NaAB with 23 Na NMR [88] and KAB with temperature resolved 39 K NMR spectroscopy [89]. Figure 5.…”

Section: Nmr Ir and Raman Spectra Of Metal Amidoboranesmentioning

confidence: 99%

Mono- and Bimetalic Amidoboranes

et al. 2016

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Abstract:In this review, we present an overview on metal amidoboranes, which have recently been considered as hydrogen storage materials for fueling of the low temperature fuel cells. We focus on amidoborane salts containing only metal cations and amidoborate anions. During the last decades, 19 new compounds from this group were described in the literature. We provide a summary of various physical and chemical properties of amidoborane compounds reported up to date.

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“…However, these approaches are difficult and costly because of safety concerns and other problems. Therefore, more and more research efforts in material development are now aiming to process light elements to achieve materials with high hydrogen content 2, 4, 5. Ammonia borane (NH 3 BH 3 , abbreviated AB) is a colorless solid that is stable at room temperature.…”

Section: Introductionmentioning

confidence: 99%

Novel theoretical studies of the dehydrogenation of LiBH₂NH₃

Wang

Zhang

Man

et al. 2012

Int J of Quantum Chemistry

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It is believed that the dehydrogenation of LiNH 2 BH 3 (LAB) proceeds through a combination of the decomposition of the LiBH 2 NH 3 (LBA) and LAB isomers. The dehydrogenation of LBA, an isomer of LAB, is discussed in this article. It is demonstrated that the loss of H 2 from LBA takes place in a two-step reaction. Studies of the dehydrogenation process were performed using Møller-Plesset second-order perturbation theory with a 6-311þþG(3df,2pd) basis set. The intrinsic reaction coordinate was calculated to determine the minimum energy paths. Finally, the rate constants were obtained using the transition-state theory (TST), TST/Eckart, canonical variational transition-state theory (CVT), CVT/smallcurvature tunneling correction, and CVT/zero-curvature tunneling correction methods from 200 to 2500 K. This is the first report on a different dehydrogenation mechanism for an alkali-metal amidoborane, and the energy barrier of LBA is much lower than that of the traditionally studied LAB.

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Solid state NMR study on the thermal decomposition pathway of sodium amidoborane NaNH2BH3

Cited by 46 publications

References 19 publications

A Composite of Complex and Chemical Hydrides Yields the First Al‐Based Amidoborane with Improved Hydrogen Storage Properties

A Composite of Complex and Chemical Hydrides Yields the First Al‐Based Amidoborane with Improved Hydrogen Storage Properties

Mono- and Bimetalic Amidoboranes

Novel theoretical studies of the dehydrogenation of LiBH₂NH₃

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Solid state NMR study on the thermal decomposition pathway of sodium amidoborane NaNH2BH3

Cited by 46 publications

References 19 publications

A Composite of Complex and Chemical Hydrides Yields the First Al‐Based Amidoborane with Improved Hydrogen Storage Properties

A Composite of Complex and Chemical Hydrides Yields the First Al‐Based Amidoborane with Improved Hydrogen Storage Properties

Mono- and Bimetalic Amidoboranes

Novel theoretical studies of the dehydrogenation of LiBH2NH3

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Novel theoretical studies of the dehydrogenation of LiBH₂NH₃