Mass-Spectrometric Investigation of the Low-Pressure Dissociation of B2H6

Sinke, E. J.; Pressley, George A.; Baylis, A. B.; Stafford, Fred E.

doi:10.1063/1.1726238

Cited by 24 publications

(10 citation statements)

References 6 publications

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“…31 The dimerization energy of borane was also estimated, during the 1960s, using electron impact ionization mass spectroscopy. Various experiments [26][27][28] tried to measure the energies of the processes…”

Section: A the Experimental Estimation Of The Dimerization Energy Of Boranementioning

confidence: 99%

Quantum Monte Carlo calculations of the dimerization energy of borane

Fracchia

Bressanini

Morosi

2011

The Journal of Chemical Physics

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Accurate thermodynamic data are required to improve the performance of chemical hydrides that are potential hydrogen storage materials. Boron compounds are among the most interesting candidates. However, different experimental measurements of the borane dimerization energy resulted in a rather wide range (-34.3 to -39.1) ± 2 kcal/mol. Diffusion Monte Carlo (DMC) simulations usually recover more than 95% of the correlation energy, so energy differences rely less on error cancellation than other methods. DMC energies of BH(3), B(2)H(6), BH(3)CO, CO, and BH(2)(+) allowed us to predict the borane dimerization energy, both via the direct process and indirect processes such as the dissociation of BH(3)CO. Our D(e) = -43.12(8) kcal/mol, corrected for the zero point energy evaluated by considering the anharmonic contributions, results in a borane dimerization energy of -36.59(8) kcal/mol. The process via the dissociation of BH(3)CO gives -34.5(2) kcal/mol. Overall, our values suggest a slightly less D(e) than the most recent W4 estimate D(e) = -44.47 kcal/mol [A. Karton and J. M. L. Martin, J. Phys. Chem. A 111, 5936 (2007)]. Our results show that reliable thermochemical data for boranes can be predicted by fixed node (FN)-DMC calculations.

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Section: A the Experimental Estimation Of The Dimerization Energy Of Boranementioning

confidence: 99%

Quantum Monte Carlo calculations of the dimerization energy of borane

Fracchia

Bressanini

Morosi

2011

The Journal of Chemical Physics

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“…Table VI compares the heats of formation of analogous sulfurand oxygen-containing ions, both for molecule ions and fragment ions. For the molecule ions the heats of formation of the oxygenated species are uniformly lower than the sulfur species, the differences being of the order of [6][7][8][9][10][11][12][13][14][15][16][17][18][19] kcal/mole. The CH3S+ ion has approximately the same heat of formation as the CH30+ ion; however, reliable data are not available for the C2H50+ ion so a comparison cannot be made for the ethyl-substituted ion.…”

Section: Energetics Of Ion Formation In Mercaptans and Sulfidesmentioning

confidence: 99%

Fragmentation of aliphatic sulfur compounds by electron impact

Keyes¹,

Harrison²

1968

J. Am. Chem. Soc.

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difference between the two transition states is substantially lower than that between I and the first transition state for ionization. On the other hand, a single-maximum potential energy diagram is sufficient for nonpolar solvents. ConclusionThe complementary evidences gained from this spectral, kinetic, and equilibrium study lead to the conclusions that (a) the colored transients from indolinospiropyrans are zwitterionic; (b) these colored transients exist in solution as an equilibrium distribution distribution of steroisomers; (c) the dominant isomer in nonpolar solvents is a planar irois-monomeric species, while that in polar and hydroxylic media is a dimeric and/or associated species. It is shown that the effect of solvent on the visible absorption spectra of the transients from indolinospiropyrans parallels that for the ionic cyanine dyes.20 This with the kinetic and equilibrium data presented indicate that contributions from quinoid species are probably minimal rather than 5671 dominant, as was previously thought17 from spectral comparisons with the nonionic merocyanines.An intriguing, but as yet unexplained feature of this work is the extremes of spectral and kinetic behavior exhibited by the indolinospiropyrans and the simple pyran and benzopyran.46 In the latter cases the transient photoproduct appears to be a molecular species. In contrast, the action of the indolino nucleus in conferring definite zwitterionic character to the transient photoproduct from spiropyrans is dramatic. This apparent ability of the indolino substituent to stabilize ionic structures is of continuing research interest in this laboratory.

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“…The spread in the literature values cited for the enthalpy of formation of BH 3 is about 27 kJ•mol Ϫ1 ͑from 79.50 to 106.69 kJ•mol Ϫ1 ͒ 1,2,[32][33][34]37,[54][55][56][57][58][59][60][61][62][63][64]. From the recent measured atomization energy reported byRuscic et al, …”

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Thermochemistry of the Boranes

Bauer

1998

Journal of Physical and Chemical Reference Data

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Articles you may be interested inThermochemistry of radicals formed by hydrogen abstraction from 1-butanol, 2-methyl-1-propanol, and butanal A compilation is presented of published experimental and computational reports ͑191 references͒ on the structures, vibrational frequencies, molar enthalpies of formation and standard entropies for 26 gas phase boranes for the temperature range from 0 to 1500 K. The thermochemical properties have been collated via standard programs and are listed in a convenient tabular format. Levels of uncertainties in the thermodynamic functions have not been assessed, because of the limited experimental and computational data. The tabulated values were fitted to standard seven-parameter ͑NASA͒ polynomials to facilitate the computation of enthalpies of formation, entropies, and heat capacities for modeling purposes. Within the context of intrinsic uncertainties, the equilibrium compositions of the gas phase were calculated, constrained to constant temperature and volume, for several boron-hydrogen ͑B/H͒ ratios, at various temperatures and pressures. The ͑unex-pected͒ results indicate that in none of the reported gas-phase kinetics studies was thermodynamic equilibrium attained, even though the measured concentration profiles appear to extrapolate to steady state product distributions.

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Mass-Spectrometric Investigation of the Low-Pressure Dissociation of B2H6

Cited by 24 publications

References 6 publications

Quantum Monte Carlo calculations of the dimerization energy of borane

Quantum Monte Carlo calculations of the dimerization energy of borane

Fragmentation of aliphatic sulfur compounds by electron impact

Thermochemistry of the Boranes

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