Thermochemistry for the Dehydrogenation of Methyl-Substituted Ammonia Borane Compounds

Grant, Daniel J.; Matus, Myrna H.; Anderson, Kevin D.; Camaioni, Donald M.; Neufeldt, Sharon R.; Lane, Clinton F.; Dixon, David A.

doi:10.1021/jp902196d

Cited by 57 publications

(94 citation statements)

References 89 publications

(160 reference statements)

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“…[13] We expect these analytes to induce the opposite response from an n-type and p-type semiconductor interface. NO, however, is an amphoteric free radical [14] and, for this reason, its interactions are far less straightforward.…”

Section: Resultsmentioning

confidence: 99%

Nanostructure‐Driven Analyte–Interface Electron Transduction: A General Approach to Sensor and Microreactor Design

2011

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A concept describing the nanostructure-directed dynamics of acid/base interaction and the balance between physisorption and chemisorption on an extrinsic semiconductor interface is evaluated and compared for n- and p-type semiconductors. The inverse hard/soft acid/base (IHSAB) concept, as it complements the HSAB concept, defines the nature of a dominant physisorption behavior and enables the creation of a matrix of controllable interactions. The technology results in the coupling of Lewis acid/base chemistry with the extrinsic semiconductor majority carriers. Nanoporous silicon layers facilitate the application of nanostructured metal/metal oxides, which provide sensitivity and selectivity for the modified interface. Applied fractional depositions can produce a dominant reversible physisorptive (sensors) or chemisorptive (microreactors) interaction at the semiconductor interface as the nanostructures act as antennas to focus the interaction. The dynamic natures of n- and p-type silicon are evaluated and compared, by focusing on the controlled manipulation of these semiconductors as they are modified with nanostructures and interact with the gas-phase analytes. The observed semiconductor responses correlate well with the temperature dependence of the extrinsic semiconductor, the population of the donor or acceptor levels, and the inherent mobilities of electrons. The response of the modified n-type semiconductors is found to exceed that of comparable p-type systems. The IHSAB concept can be extended to assess the properties of several additional semiconductor interfaces including nanowires. The results obtained not only pertain to sensor and microreactor array design, but also suggest the importance of the dynamic changes created, as the majority charge-carrier concentrations are manipulated and the Fermi energies are modified through chemical interaction.

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Section: Resultsmentioning

confidence: 99%

Nanostructure‐Driven Analyte–Interface Electron Transduction: A General Approach to Sensor and Microreactor Design

2011

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“…Ammonia acts as a Lewis base towards BH 3 with which it forms ammonia‐borane, NH 3 BH 3 . The well‐studied prototypical BN dative bond has a length of 1.658 Å 38–40. The structure of the 1· NH 3 complex, however, does not show this BN dative bond.…”

Section: Resultsmentioning

confidence: 99%

The Lewis Acidity of the BO Triple Bond in Methyl(oxo)borane

Bettinger

Brough

Grunenberg

2013

Zeitschrift anorg allge chemie

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The interaction of methyl(oxo)borane, CH3BO, with typical Lewis bases (nitrogen based and N‐heterocyclic carbenes) was investigated using density functional theory (B97‐D, TPSS‐D3), double hybrid density functionals (PWPB95‐D3, B2PLYP‐D3) in conjunction with empirical dispersion corrections, and coupled cluster theory involving singles, doubles, and a perturbative estimate of triple excitations [CCSD(T)]. A polarized quadruple‐zeta basis set was used throughout. The interaction energies computed with the double‐hybrid methods agree very well with CCSD(T). Compared to typical boron Lewis acids, the interaction energies are much smaller for methyl(oxo)borane, indicating that the BO triple bond results in significantly reduced Lewis acidity. An analysis of the mechanical bond strengths in CH3BO and its complexes indicates that the relaxed BO force constants (compliance constants) and the stretching vibrations decrease with increasing strengths of the dative interactions.

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“…While this is undesirable, a mixed amine borane system where a small ratio of a substituted amine borane is combined with ammonia borane could result in sufficient quantities of (CBNH)" formation. Dixon et al [22] have shown significant reductions to the melting point of mixed methylamine borane/ammonia borane systems. The resultant material likely must still undergo chemical processing to regenerate the original hydrogen fuel; however, this chemical processing potentially will be less energy intensive.…”

Section: Discussionmentioning

confidence: 99%

“…These (CBNH)" compounds are potentially less energy intensive making regeneration of the amine borane fuel more feasible [22]. In the present study, rerr-butylamine borane is investigated by heteronuclear in situ solid state NMR to understand hydrogen release from a hydrocarbon containing amine borane.…”

Section: Introductionmentioning

confidence: 99%

Thermal Decomposition of T‐Butylamine Borane Studied by in Situ Solid State NMR

Feigerle¹,

Smyrl²,

Morrell³

et al. 2010

Ceramic Transactions Series

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Amine boranes are a class of hydrogen storage materials which release significant yields of hydrogen gas upon heating to temperatures relevant for automotive applications. The fhermodynamic stability of this class of amine boranes is correlated with the extensive dihydrogen bonding between hydrides bound to boron and amine protons. Further, the hydrogen evolution follows a bimolecular pathway via the di-hydrogen bonding network. The thermal decomposition of t-butylamine borane (tBuAB), (CH 3 )3CNH 2 BH3, has been studied in order to understand the reaction pathway of hydrogen sorption and the impact of the t-butyl substitution dehydrogenation thermodynamics. Ή , U B , and l3 C solid state nuclear magnetic resonance (NMR) spectroscopy has revealed that heating initiates two separate reaction pathways: isomerization and hydrocarbon abstraction resulting in varying yields of isobutane and hydrogen. It is also possible that tBuAB dissociates about the N-B bond giving rise to borane stretching modes in the gas FTIR. Trapped t-butylamine (tBuA) which slowly diffuses from the tBuAB solid in 13 C NMR studies appears to be present; however, this spectral region is convoluted by other decomposition products. n B NMR indicates that the major reaction pathway results in hydrogen evolution with isobutane formation being present in smaller yields. The t-butyl substitution lowers the thermodynamic stability -compared to NH3BH3-but results in impure hydrogen gas stream and lowered capacity due to isobutene evolution. INTRODUCTIONDevelopment of suitable materials to store hydrogen for automotive use has received pointed attention over the past decade [1], Significant progress has been made with the discovery of novel chemical hydrides, complex metal hydrides, and adsorption substrates which continue to optimize both thermodynamics and kinetics of hydrogen sorption [2]. Chemical hydrides typically offer the largest theoretical gravimetric capacities. Autrey et al. [3] have recently shown that mechanical milling of alkali metal hydrides with ammonia borane can further lower the decomposition temperature. In all cases, however, many challenges remain in order to meet the current US DOE performance targets [4].Amine boranes are being considered for hydrogen storage materials since they contain significant quantities of hydrogen which potentially can be released at low temperatures (80-150 °C) via chemical reactions. Ammonia borane, NH3BH3, is one of the most promising in this class as it decomposes to release greater than two moles of pure hydrogen gas (14 wt %) below 160 °C [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19], Although isoelectronic to ethane, NH3BH3 is a solid at room temperature due to the di-hydrogen bonding network formed between the amine protons and boron hydrides in the solid state lattice. Further, it has been shown that the hydrogen release mechanism involves transformation and isomerization to an ionic dimer where a hydride migrates from one boron to the adjacent boron in the dimer [20]. The greatest ch...

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Thermochemistry for the Dehydrogenation of Methyl-Substituted Ammonia Borane Compounds

Cited by 57 publications

References 89 publications

Nanostructure‐Driven Analyte–Interface Electron Transduction: A General Approach to Sensor and Microreactor Design

Nanostructure‐Driven Analyte–Interface Electron Transduction: A General Approach to Sensor and Microreactor Design

The Lewis Acidity of the BO Triple Bond in Methyl(oxo)borane

Thermal Decomposition of T‐Butylamine Borane Studied by in Situ Solid State NMR

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Thermochemistry for the Dehydrogenation of Methyl-Substituted Ammonia Borane Compounds

Cited by 57 publications

References 89 publications

Nanostructure‐Driven Analyte–Interface Electron Transduction: A General Approach to Sensor and Microreactor Design

Nanostructure‐Driven Analyte–Interface Electron Transduction: A General Approach to Sensor and Microreactor Design

The Lewis Acidity of the BO Triple Bond in Methyl(oxo)­borane

Thermal Decomposition of T‐Butylamine Borane Studied by in Situ Solid State NMR

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The Lewis Acidity of the BO Triple Bond in Methyl(oxo)borane