Amminelithium Amidoborane Li(NH3)NH2BH3: A New Coordination Compound with Favorable Dehydrogenation Characteristics

Xia, Guanglin; Yu, Xuebin; Guo, Yanhui; Wu, Zhu; Yang, Chuanzhen; Liu, Huan; Dou, Shi Xue

doi:10.1002/chem.200903220

Cited by 64 publications

(62 citation statements)

References 52 publications

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“…CaAB was prepared according to literature procedures. [13] 15 N-labeled CaAB·2 NH 3 was prepared by reacting Ca( 15 NH 2 ) 2 with unlabeled AB (molar ratio of 1:2) . All materials were handled inside a glove-box filled with purified argon.…”

Section: Discussionmentioning

confidence: 99%

“…[7][8][9] Kim and co-workers suggested that the metal cation "relays" the hydride, and the barrier for transfer was found to correlate with the ionic character of the metal-hydride interaction. [9] More recently, a new subfamily of metal amidoboranes, which are known as metal amidoborane ammoniates, was prepared by reacting AB with Ca(NH 2 ) 2 , LiNH 2 , or MgNH, yielding Ca(NH 2 BH 3 ) 2 ·2 NH 3 (CaAB·2 NH 3 ), [11] Li(NH 2 BH 3 ) 2 ·NH 3 (LiAB·NH 3 ), [12,13] and Mg(NH 2 BH 3 ) 2 ·NH 3 (MgAB·NH 3 ). [14] The hydrogen contents of these compounds are ca.…”

Section: Introductionmentioning

confidence: 99%

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Mechanistic Investigation on the Formation and Dehydrogenation of Calcium Amidoborane Ammoniate

Chua¹,

Wen²,

Shaw³

et al. 2012

ChemSusChem

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Possessing high H2 capacities and interesting dehydrogenation behavior, metal amidoborane ammoniates were prepared by reacting Ca(NH2)2, MgNH, and LiNH2 with ammonia borane to form Ca(NH2BH3)2⋅2 NH3, Mg(NH2BH3)2⋅NH3, and Li(NH2BH3)2⋅NH3 (LiAB⋅NH3). Insight into the mechanisms of amidoborane ammoniate formation and dehydrogenation was obtained by using isotopic labeling techniques. Selective 15N and 2H labeling showed that the formation of the ammoniate occurs via the transfer of one H(N) from ammonia borane to the [NH2]− unit in Ca(NH2)2 giving rise to NH3 and [NH2BH3]−. Supported by theoretical calculations, it is suggested that the improved dehydrogenation properties of metal amidoborane ammoniates compared to metal amidoboranes are a result of the participation of a strong dihydrogen bond between the NH3 molecule and [NH2BH3]−. Our study elucidates the reaction pathway involved in the synthesis and dehydrogenation of Ca(NH2BH3)2⋅2 NH3, and clarifies our understanding of the role of NH3, that is, it is not only involved in stabilizing the structure, but also in improving the dehydrogenation properties of metal amidoboranes.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Mechanistic Investigation on the Formation and Dehydrogenation of Calcium Amidoborane Ammoniate

Chua¹,

Wen²,

Shaw³

et al. 2012

ChemSusChem

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“…A variety of B-N amidoborane ammoniates, have previously been synthesized by reacting MAB and NH3, including LiNH2BH3·NH3 [16], Mg(NH2BH3)2·3NH3 [17], and Ca(NH2BH3)2·NH3 [18]. However, to the best of our knowledge, there has been no prior report of the synthesis of an aluminum analog.…”

Section: Introductionmentioning

confidence: 99%

Efficient Synthesis of an Aluminum Amidoborane Ammoniate

et al. 2015

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“…24,25 These ammoniates demonstrated significantly improved dehydrogenation properties owing to the active participation of NH 3 in the dehydrogenation process. Despite the salient role of NH 3 in the ammoniate complexes, contamination of H 2 by a small amount of NH 3 is unavoidable.…”

Section: ■ Introductionmentioning

confidence: 99%

Monoammoniate of Calcium Amidoborane: Synthesis, Structure, and Hydrogen-Storage Properties

Chua

Zhou

et al. 2012

Inorg. Chem.

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The monoammoniate of calcium amidoborane, Ca-(NH 2 BH 3 ) 2 ·NH 3 , was synthesized by ball milling an equimolar mixture of CaNH and AB. Its crystal structure has been determined and was found to contain a dihydrogen-bonded network. Thermal decomposition under an open-system begins with the evolution of about 1 equivalent/formula unit (equiv.) of NH 3 at temperatures <100°C followed by the decomposition of Ca(NH 2 BH 3 ) 2 to release hydrogen. In a closed-system thermal decomposition process, hydrogen is liberated in two stages, at about 70 and 180°C, with the first stage corresponding to an exothermic process. It has been found that the presence of the coordinated NH 3 has induced the dehydrogenation to occur at low temperature. At the end of the dehydrogenation, about 6 equiv. (∼ 10.2 wt %) of hydrogen can be released, giving rise to the formation of CaB 2 N 3 H. ■ INTRODUCTIONThe increasing scarcity of fossil fuels and their link to global warming underscores the need to shift our current energy sources to more environmentally friendly and efficient alternatives. Hydrogen has been regarded as the most promising future fuel as it is high in energy and when it burns, it produces no pollution. However, one of the most important technological challenges facing a hydrogen economy is the development of safe and energy-efficient hydrogenstorage materials, especially for use with hydrogen fuel-cell vehicles. Ammonia borane (NH 3 BH 3 , AB) has drawn significant attention as one of the potential hydrogen-storage materials because of its high hydrogen capacity (ca. 19.6 wt %) and moderate dehydrogenation properties. However, its widespread application is restricted because of the slow dehydrogenation kinetics and the release of volatile byproduct.1,2 Aiming to improve its hydrogen storage properties, active research activities have been focused on the catalytic dehydrocoupling of ammonia borane and its derivatives, that is, primary and secondary amineboranes (RNH 2 BH 3 and R 2 NHBH 3 ).3−6 Besides kinetic improvement, ammonia borane with its potential N−H group which protonic H + is of the weak Lewis acidity, could be functionalized for thermodynamic improvement. As results of the introduction of a functional group by reacting ammonia borane with a stronger Lewis acid, that is, metal hydrides, a series of single-metal and double-metal amidoboranes consisting of metal cations and amidoborane anions were developed, including amidoboranes of Li,7,8 Na,7 K, 9 Ca, 10,11 Sr, 12 Y, 13 Na 2 Mg, 14 NaMg, 15 and NaLi. 16 These metal amidoboranes are found to exhibit significant improvement over the parent AB, including reduced dehydrogenation temperature with moderate dehydrogenation thermodynamics, improved dehydrogenation kinetics, and suppression of the release of volatile byproduct. In addition, intensive mechanistic investigations were also studied to understand the role of metal cation in the improved dehydrogenation properties. 3,17−21 Besides metal hydrides, metal amides or imides, which typically contain s...

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Amminelithium Amidoborane Li(NH₃)NH₂BH₃: A New Coordination Compound with Favorable Dehydrogenation Characteristics

Cited by 64 publications

References 52 publications

Mechanistic Investigation on the Formation and Dehydrogenation of Calcium Amidoborane Ammoniate

Mechanistic Investigation on the Formation and Dehydrogenation of Calcium Amidoborane Ammoniate

Efficient Synthesis of an Aluminum Amidoborane Ammoniate

Monoammoniate of Calcium Amidoborane: Synthesis, Structure, and Hydrogen-Storage Properties

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