Coordination of aminoborane, NH2BH2, dictates selectivity and extent of H2 release in metal-catalysed ammonia borane dehydrogenation

Pons, Vincent; Baker, R. Tom; Szymczak, Nathaniel K.; Heldebrant, David J.; Linehan, John C.; Matus, Myrna H.; Grant, Daniel J.; Dixon, David A.

doi:10.1039/b809190k

Cited by 170 publications

(245 citation statements)

References 24 publications

Supporting

Mentioning

225

Contrasting

Unclassified

Order By: Relevance

“…This side reaction can be considered as evidence for the generation of BH 2 NH 2 , which is presumed to be able to catalyze the dehydrogenation of AB. [13,14] However, it was only a minor competition reaction here, because 1 equiv of AB can hydrogenate 2 equiv of 1 a nearly quantitatively if given enough time (Table 1, entry 6). A scrambling experiment with AB and its doubly deuterated isotopologue A(D)B(D) was also carried out to see whether AB would decompose at such conditions.…”

mentioning

confidence: 93%

Transfer Hydrogenation of Imines with Ammonia–Borane: A Concerted Double‐Hydrogen‐Transfer Reaction

et al. 2010

View full text Add to dashboard Cite

show abstract

mentioning

confidence: 93%

Transfer Hydrogenation of Imines with Ammonia–Borane: A Concerted Double‐Hydrogen‐Transfer Reaction

et al. 2010

View full text Add to dashboard Cite

show abstract

“…They have been studied using a combination of spectroscopic techniques, isotope labeling, trapping studies, and theory and modeling. These studies have led to the proposed general mechanistic scheme of catalytic dehydrogenation of ammonia borane via transition metalmediated catalysts as proposed by the team of Baker, Linehan, and Dixon [93] and shown in Figure 15. The metal catalyzed hydrogen release from ammonia borane is proposed to proceed by one of two paths depending on the nature of the catalyst.…”

Section: Catalytic Release Of Hydrogen From Ammonia Boranementioning

confidence: 99%

Accelerating the Understanding and Development of Hydrogen Storage Materials: A Review of the Five-Year Efforts of the Three DOE Hydrogen Storage Materials Centers of Excellence

Klebanoff

Ott

Simpson

et al. 2014

Metallurgical and Materials Transactions E

View full text Add to dashboard Cite

A technical review of the progress achieved in hydrogen storage materials development through the U.S. Department of Energy's (DOE) Fuel Cell Technologies Office and the three Hydrogen Storage Materials Centers of Excellence (CoEs), which ran from 2005 to 2010 is presented. The three CoEs were created to develop reversible metal hydrides, chemical hydrogen storage materials, and high-specific-surface-area (SSA) hydrogen sorbents. For each CoE, the approach taken is specified, key outcomes and accomplishments identified, and recommendations for future work are suggested. The Metal Hydride Center of Excellence addresses work on destabilized hydrides, including the LiBH/Mg 2 NiH 4 system, borohydrides, amides, and alanes; and compares the best materials to DOE targets. The Chemical Hydrogen Storage Center of Excellence discusses the classes of materials studied for chemical hydrogen storage, focusing on ammonia borane and examines the progress in developing efficient regeneration schemes. The Hydrogen Sorption Center of Excellence describes the progress in developing high-SSA sorbents and pathways for developing improved materials capable of achieving DOE targets. The phenomenon of spillover is also observed and its importance to ensuring improved measurements is discussed. Through the five-year effort of the Hydrogen Storage Materials Centers of Excellence, significant progress was achieved in developing and understanding hydrogen storage materials.

show abstract

“…11 B NMR spectra in THF-D 8 showing the decomposition of 3a at room temperature. Initially 3a was formed by keeping a NMR sample of 1a with AB (3 : 1 molar ratio) at -40…”

Section: Fig 3 In Situmentioning

confidence: 99%

“…The catalytic reaction of AB in the presence of cyclohexene was reported to result in a hydroboration reaction with formation of Cy 2 BNH 2 when using rhodium 8 or platinum 9 catalysts. On the other hand, olefins including cyclohexene were seen to be transfer hydrogenated by AB or dimethylamine borane (DMAB) using Rh colloid or nitrosyl Re(I) complexes.…”

Section: Introductionmentioning

confidence: 99%

Synthetic and mechanistic studies of metal-free transfer hydrogenations applying polarized olefins as hydrogen acceptors and amine borane adducts as hydrogen donors

2012

View full text Add to dashboard Cite

Metal-free transfer hydrogenation of polarized olefins (RR'C=CEE': R, R' = H or organyl, E, E' = CN or CO(2)Me) using amine borane adducts RR'NH-BH(3) (R = R' = H, AB; R = Me, R' = H, MAB; R = (t)Bu, R' = H, tBAB; R = R' = Me, DMAB) as hydrogen donors, were studied by means of in situ NMR spectroscopy. Deuterium kinetic isotope effects and the traced hydroboration intermediate revealed that the double H transfer process occurred regio-specifically in two steps with hydride before proton transfer characteristics. Studies on substituent effects and Hammett correlation indicated that the rate determining step of the H(N) transfer is in agreement with a concerted transition state. The very reactive intermediate NH(2)=BH(2)] generated from AB was trapped by addition of cyclohexene into the reaction mixture forming Cy(2)BNH(2). The final product borazine (BHNH)(3) is assumed to be formed by dehydrocoupling of NH(2)=BH(2)] or its solvent stabilized derivative NH(2)=BH(2)]-(solvent), rather than by dehydrogenation of cyclotriborazane (BH(2)NH(2))(3) which is the trimerization product of NH (2) Metal-free transfer hydrogenation of polarized olefins (RR¢C CEE¢: R, R¢ = H or organyl, E, E¢ = CN or CO 2 Me) using amine borane adducts RR¢NH-BH 3 (R = R¢ = H, AB; R = Me, R¢ = H, MAB; R = t Bu, R¢ = H, tBAB; R = R¢ = Me, DMAB) as hydrogen donors, were studied by means of in situ NMR spectroscopy. Deuterium kinetic isotope effects and the traced hydroboration intermediate revealed that the double H transfer process occurred regio-specifically in two steps with hydride before proton transfer characteristics. Studies on substituent effects and Hammett correlation indicated that the rate determining step of the H N transfer is in agreement with a concerted transition state.

show abstract

Coordination of aminoborane, NH2BH2, dictates selectivity and extent of H2 release in metal-catalysed ammonia borane dehydrogenation

Abstract: In situ(11)B NMR monitoring, computational modeling, and external trapping studies show that selectivity and extent of H(2) release in metal-catalysed dehydrogenation of ammonia borane, NH(3)BH(3), are determined by coordination of reactive aminoborane, NH(2)BH(2), to the metal center.

Cited by 170 publications

References 24 publications

Transfer Hydrogenation of Imines with Ammonia–Borane: A Concerted Double‐Hydrogen‐Transfer Reaction

Transfer Hydrogenation of Imines with Ammonia–Borane: A Concerted Double‐Hydrogen‐Transfer Reaction

Accelerating the Understanding and Development of Hydrogen Storage Materials: A Review of the Five-Year Efforts of the Three DOE Hydrogen Storage Materials Centers of Excellence

Synthetic and mechanistic studies of metal-free transfer hydrogenations applying polarized olefins as hydrogen acceptors and amine borane adducts as hydrogen donors

Contact Info

Product

Resources

About