Synthesis and structure of a magnesium–amidoborane complex and its role in catalytic formation of a new bis-aminoborane ligand

Spielmann, Jan; Bolte, Michael; Harder, Sjoerd

doi:10.1039/b914979a

Cited by 98 publications

(90 citation statements)

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“…In Ca(NH 2 BH 3 ) 2 ·NH 3 , the Ca 2+ cation has a trigonal bipyramidal coordination geometry, surrounded by two N's of the NH 2 As a result of the Ca−N interaction, the N−H bonds in the adducted NH 3 were lengthened (1.025 Å versus 1.020 Å in NH 3 gas). This is further evidenced by the absences of the high-frequency N−H stretching of NH 3 (∼3444 cm 28−30 were also detected in Ca(NH 2 BH 3 ) 2 ·NH 3 , revealing a strengthened B−N bond and weakened B−H bond, respectively, in the structure.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…A hydrogen-storage capacity of ∼10.2 wt % can be achieved upon heating to 300°C with the detection of less than 0.1 equiv. of NH 3 , showing higher hydrogen capacity with improved purity as compared to Ca-(NH 2 …”

Section: ■ Conclusionmentioning

confidence: 99%

“…Despite the salient role of NH 3 in the ammoniate complexes, contamination of H 2 by a small amount of NH 3 is unavoidable. It is worth mentioning that the presence of even a few ppm of NH 3 would poison the fuel cell. Earlier study in the investigation of the ammoniate samples revealed that by reducing the amount of N−H group in the starting materials, that is, using MgNH instead of Mg(NH 2 ) 2 , monoammoniate of magnesium amidoborane can be formed, and it demonstrates the capability of complete conversion of NH 3 to H 2 in the dehydrogenation process.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Earlier study in the investigation of the ammoniate samples revealed that by reducing the amount of N−H group in the starting materials, that is, using MgNH instead of Mg(NH 2 ) 2 , monoammoniate of magnesium amidoborane can be formed, and it demonstrates the capability of complete conversion of NH 3 to H 2 in the dehydrogenation process. 23 Therefore, in this study, we tentatively reduced the NH 3 27 A mixture of CaNH and NH 3 BH 3 in a 1:2 molar ratio was ball milled under an inert atmosphere for 10 h on a Retsch PM400 planetary mill. Ball milling gave a solid product and hardly any gaseous product could be detected.…”

Section: ■ Introductionmentioning

confidence: 99%

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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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Section: ■ Results and Discussionmentioning

confidence: 99%

Section: ■ Conclusionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

See 2 more Smart Citations

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

Chua

Zhou

et al. 2012

Inorg. Chem.

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“…The lattice parameters are: a = 7.1051(8) Å, b = 13.930(1) Å, c = 5.1477(7) Å, V = 509.489 Å 3 with Z = 8 [19]. Volume of a formula unit is equal to 63 Synthesis of β-LiAB considers a special 5 h regime of ball milling of a mixture containing ammonia borane and LiH in molar ratio 1:1 [20]. Firstly, as an intermediate product LiNH 2 BH 3¨N H 3 BH 3 is formed, which later reacts with LiH while yielding β-LiAB.…”

Section: Alkali 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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Alkaline Earth Metals: Organometallic ChemistryUpdate based on the original article by Jacob S. Alexander, Marites Guino‐o, Maria Felisa Zuniga, Roger C. Hahn and Karin Ruhlandt‐Senge,Encyclopedia of Inorganic ChemistrySecond Edition, © 2005, John Wiley & Sons, Ltd.

Goos¹,

Flores²,

Takahashi³

et al. 2012

Encyclopedia of Inorganic and Bioinorganic Chemistry

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The organometallic chemistry of the alkaline‐earth metals has undergone a renaissance during the last 20 years with heavy organoalkaline‐earth metal compounds becoming recognized as an area of organometallic chemistry with significant potential. Intense research efforts have provided a series of synthetic methodologies that provided access to a rapidly growing family of compounds not thought possible only recently. As a result, this improved insight did not only provide the basis for a more detailed understanding of the metal‐ligand bonding characteristics but also paved the way toward a number of applications including uses as diverse as in polymerization initiation, organic synthetic chemistry, catalysis, and materials chemistry. This article summarizes some of the recent, exciting developments in regards to alkaline‐earth organometallics.

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Synthesis and structure of a magnesium–amidoborane complex and its role in catalytic formation of a new bis-aminoborane ligand

Abstract: A synthetic route to a magnesium-amidoborane complex and its role in the catalytic conversion of a substituted ammonia-borane RNH(2)BH(3) into HB(NHR)(2) is discussed.

Cited by 98 publications

References 12 publications

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

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

Mono- and Bimetalic Amidoboranes

Alkaline Earth Metals: Organometallic ChemistryUpdate based on the original article by Jacob S. Alexander, Marites Guino‐o, Maria Felisa Zuniga, Roger C. Hahn and Karin Ruhlandt‐Senge,Encyclopedia of Inorganic ChemistrySecond Edition, © 2005, John Wiley & Sons, Ltd.

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