ChemInform Abstract: GAS PHASE ELECTROCATALYTIC OXIDATION OF SULFUR DIOXIDE BY SOLID STATE ELECTROCHEMICAL TECHNIQUE

AbstractThe crystal structure and an improved synthesis of 1,3,5-trisilacyclohexane are reported. The solid state structure is compared with the reported structure determined in the gas phase by gas electron diffraction (GED). 1,3,5-Trisilacyclohexane adopts a chair conformation in the solid state. The Si–C bond lengths as well as all angles of 1,3,5-trisilacyclohexane in the solid state have similar dimensions compared to the structure in the gaseous phase.

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Utilizing the Combined Power of Theory and Experiment to Understand Molecular Structure – Solid-State and Gas-Phase Investigation of Morpholine Borane

Australian Journal of Chemistry ◽

10.1071/ch19492 ◽

2020 ◽

Vol 73 (8) ◽

pp. 794

Author(s):

Aliyu M. Ja'o ◽

Derek A. Wann ◽

Conor D. Rankine ◽

Matthew I. J. Polson ◽

Sarah L. Masters

Keyword(s):

Molecular Structure ◽

Solid State ◽

Gas Phase ◽

Hydrogen Generation ◽

Energy Requirement ◽

Hydrogen Release ◽

X Ray Diffraction ◽

Structural Variations ◽

Dehydrogenation Reaction ◽

Quantum Chemical Methods

The molecular structure of morpholine borane complex has been studied in the solid state and gas phase using single-crystal X-ray diffraction, gas electron diffraction, and computational methods. Despite both the solid-state and gas-phase structures adopting the same conformation, a definite decrease in the B–N bond length of the solid-state structure was observed. Other structural variations in the different phases are presented and discussed. To explore the hydrogen storage potential of morpholine borane, the potential energy surface for the uncatalyzed and BH3-catalyzed pathways, as well as the thermochemistry for the hydrogen release reaction, were investigated using accurate quantum chemical methods. It was observed that both the catalyzed and uncatalyzed dehydrogenation pathways are favourable, with a barrier lower than the B–N bond dissociation energy, thus indicating a strong propensity for the complex to release a hydrogen molecule rather than dissociate along the B–N bond axis. A minimal energy requirement for the dehydrogenation reaction has been shown. The reaction is close to thermoneutral as demonstrated by the calculated dehydrogenation reaction energies, thus implying that this complex could demonstrate potential for future on-board hydrogen generation.

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The structure of 1-formyl-3-phenyl-Δ2-pyrazoline in the gas phase (DFT calculations), in solution (NMR) and in the solid state (X-ray crystallography)

Journal of Molecular Structure ◽

10.1016/j.molstruc.2003.10.041 ◽

2004 ◽

Vol 689 (3) ◽

pp. 251-254 ◽

Cited By ~ 14

Author(s):

I. Alkorta ◽

J. Elguero ◽

A. Fruchier ◽

N. Jagerovic ◽

G.P.A. Yap

Keyword(s):

Solid State ◽

Dft Calculations ◽

Gas Phase ◽

Solution Nmr ◽

X Ray ◽

X Ray Crystallography

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Structural studies of organoboron compounds. LVI. 1-Benzyl-7-methyl-3,5-diphenyl-2,4,6-trioxa-1-azonia-3-bora-5-boratabicyclo[3.3.0]octane and 1,4,6,9-tetramethyl-2,7-diphenyl-3,8,11,12-tetraoxa-1,6-diazonia-2,7-diboratatricyclo[5.3.1.12,6]dodecane

Canadian Journal of Chemistry ◽

10.1139/v92-357 ◽

1992 ◽

Vol 70 (11) ◽

pp. 2809-2817 ◽

Cited By ~ 7

Author(s):

Wolfgang Kliegel ◽

Gottfried Lubkowitz ◽

Steven J. Rettig ◽

James Trotter

Keyword(s):

Solid State ◽

Gas Phase ◽

Phenylboronic Acid ◽

Direct Methods ◽

Structural Studies ◽

Triclinic Space Group ◽

Full Matrix ◽

X Ray ◽

Molar Ratios ◽

New Type

The preparation of the N-(2-hydroxypropyl)-N-alkylhydroxylamines, 6a (R = CH3) and 6b (R = CH2Ph), and their reactions with phenylboronic acid are described. Regardless of the molar ratios of reactants employed, the reaction with 6b leads to the 1:2 condensate 1-benzyl-7-methyl-3,5-diphenyl-2,4,6-trioxa-1-azonia-3-bora-5-boratabicyclo[3.3.0]octane, 7, while that with 6a gives rise to the 1:1 condensate 1,4,6,9-tetramethyl-2,7-diphenyl-3,8,11,12-tetraoxa-1,6-diazonia-2,7-diboratatricyclo[5.3.1. 12,6]dodecane, 11 (the cyclic BONBON dimer of 4,6-dimethyl-2-phenyl-1,3-dioxa-4-aza-2-boracyclohexane, 9). Compounds 7 and 11 both crystallize in the triclinic space group [Formula: see text]: for 7; a = 13.126(1), b = 15.337(1), c = 10.9469(5) Å, α = 91.727(5), β = 104.647(5), γ = 72.922(7)°, Z = 4; and for 11; a = 9.0807(4), b = 9.1653(3), c = 6.4876(2) Å, α = 97.708(3), β = 108.830(3), γ = 89.188(4)°, Z = 1. The structures were solved by direct methods and were refined by full-matrix least-squares procedures to R = 0.038 and 0.032 for 5879 and 1827 reflections with I ≥ 3σ(F2), respectively. Compound 7 has the expected bicyclic pyroboronate structure, but represents the first reported N-substituted example of this type of compound. Bond lengths involving boron in 7 are (C) O—B(sp3) = 1.428(2) and 1.420(2), (B)O—B(sp3) = 1.472(2) and 1.468(2), N—B(sp3) = 1.737(2) and 1.762(2), C(phenyl)—B(sp3) = 1.588(2) and 1.584(2), (N)O—B(sp2) = 1.402(2) and 1.404(2), (B)O—B(sp2) = 1.331(2) and 1.329(2), C(phenyl)—B(sp2) = 1.555(3) and 1.553(2) Å. The X-ray analysis establishes a centrosymmetric, twofold N → B coordinated, dimeric structure in the solid state for 11 in which each B—O—N segment of a central six-membered BONBON ring is bridged by an O—C—C moiety. Compound 11 represents the first fully characterized example of a new type of "BONBON" compound. Bond distances involving the boron atom are (N)O—B = 1.465(1), (C)O—B = 1.428(1), N—B = 1.695(2), and C(phenyl)—B = 1.607(2) Å. Spectroscopic evidence indicates that in solution and in the gas phase this material exists predominantly as the monomer 9.

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