Kinetics and mechanism of the thermolysis and photolysis of binary boranes

Greenwood, N. N.; Greatrex, Robert

doi:10.1351/pac198759070857

Cited by 50 publications

(40 citation statements)

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“…To get to a trimer, one would likely need to break down a dimer, a costly step in enthalpy, which has nevertheless been suggested 43 in the pyrolysis of B 2 H 6 to yield higher boranes, that is, The measured dissociation enthalpy for step I is about 36 ± 3 kcal/mol (around 450 K). 33 Step II, the formation of a B 3 H 9 …”

Section: Journal Of the American Chemical Societymentioning

confidence: 99%

BH₃ under Pressure: Leaving the Molecular Diborane Motif

Yao

Hoffmann

2011

J. Am. Chem. Soc.

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Molecular and crystalline structures of (BH 3 ) n have been theoretically studied in the pressure regime from 1 atm to 100 GPa. At lower pressures, crystals of the familiar molecular dimer are the structure of choice. At 1 atm, in addition to the well-characterized β diborane structure, we suggest a new polymorph of B 2 H 6 , fitting the diffraction lines observed in the very first X-ray diffraction investigation of solid diborane, that of Mark and Pohland in 1925. We also find a number of metastable structures for oligomers of BH 3 , including cyclic trimers, tetramers, and hexamers. While the higher oligomers as well as one-dimensional infinite chains (bent at the bridging hydrogens) are less stable than the dimer at ambient pressure, they are stabilized, for reasons of molecular compactness, by application of external pressure. Using periodic DFT calculations, we predict that near 4 GPa a molecular crystal constructed from discrete trimers replaces the β diborane structure as the most stable phase and remains as such until 36 GPa. At higher pressures, a crystal of polymeric, one-dimensional chains is preferred, until at least 100 GPa.

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Section: Journal Of the American Chemical Societymentioning

confidence: 99%

BH₃ under Pressure: Leaving the Molecular Diborane Motif

Yao

Hoffmann

2011

J. Am. Chem. Soc.

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“…it can decompose to B 4 H 8 and B 3 H 7 [5]. Pentaborane is additionally formed in the thermal decomposition of diborane at 250°C and 0.16 bar with the yield of 33% [3]:…”

Section: Introductionmentioning

confidence: 99%

Catalyst Deactivation in Diborane Decomposition

et al. 2005

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“…42 Figure 3 compares the H 2 , diborane, and triborane releases of as-received LiBH 4 , heat-treated Mg(BH 4 ) 2 , and as-prepared Li/Mg(BH 4 ) 3 , respectively. As shown in Figure 3, a large quantity of diborane is emitted during the decomposition of Mg(BH 4 ) 2 and LiBH 4 .…”

Section: Resultsmentioning

confidence: 99%

Decomposition Behavior of Eutectic LiBH₄–Mg(BH₄)₂ and Its Confinement Effects in Ordered Nanoporous Carbon

et al. 2014

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We present the crystal structure, diborane (B 2 H 6 ) and triborane (B 3 H n ) evolution, and dehydrogenation kinetics, of both bulk and nanoconfined Li/Mg(BH 4 ) 3 in a highly ordered nanoporous carbon template. The bialkali borohydride Li/Mg(BH 4 ) 3 mainly forms a structure similar to that of α-Mg(BH 4 ) 2 . The decomposition temperature of Li/Mg(BH 4 ) 3 lies between that of LiBH 4 and Mg(BH 4 ) 2 . A direct line-of-site residual gas analyzer mass spectrometer shows that very little diborane and no detectable triborane are released during the decomposition of bulk Li/Mg(BH 4 ) 3 , which is quite different from Mg(BH 4 ) 2 or LiBH 4 , indicating that the dual-cation borohydride undergoes a different decomposition pathway, and that the reaction pathway related to diborane or triborane formation was suppressed. The nanoconfined Li/Mg(BH 4 ) 3 shows a higher cycling capacity as well as a lower decomposition temperature but, in contrast, produces more diborane and triborane in comparison with bulk Li/ Mg(BH 4 ) 3 .

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Kinetics and mechanism of the thermolysis and photolysis of binary boranes

Abstract: Abstract

Cited by 50 publications

References 2 publications

BH₃ under Pressure: Leaving the Molecular Diborane Motif

BH₃ under Pressure: Leaving the Molecular Diborane Motif

Catalyst Deactivation in Diborane Decomposition

Decomposition Behavior of Eutectic LiBH₄–Mg(BH₄)₂ and Its Confinement Effects in Ordered Nanoporous Carbon

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Kinetics and mechanism of the thermolysis and photolysis of binary boranes

Abstract: Abstract

Cited by 50 publications

References 2 publications

BH3 under Pressure: Leaving the Molecular Diborane Motif

BH3 under Pressure: Leaving the Molecular Diborane Motif

Catalyst Deactivation in Diborane Decomposition

Decomposition Behavior of Eutectic LiBH4–Mg(BH4)2 and Its Confinement Effects in Ordered Nanoporous Carbon

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Product

Resources

About

BH₃ under Pressure: Leaving the Molecular Diborane Motif

BH₃ under Pressure: Leaving the Molecular Diborane Motif

Decomposition Behavior of Eutectic LiBH₄–Mg(BH₄)₂ and Its Confinement Effects in Ordered Nanoporous Carbon