The evolution of hydrogen atom parameters under changing external conditions by time-of-flight single crystal neutron diffraction

Wilson, Chick C.

doi:10.1080/08893110701565913

Cited by 20 publications

(7 citation statements)

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“…This phenomenon is often observed in methyl groups in many crystal structures, even in cases where the methyl group rotation is hindered. 10 Nitromethane is therefore a model system for one of the most common manifestations of anharmonic thermal motion in crystallography.…”

Section: Determination Of the Experimental Equilibrium Structure Of Smentioning

confidence: 99%

Determination of the experimental equilibrium structure of solid nitromethane using path-integral molecular dynamics simulations

Reilly

Habershon

Morrison

et al. 2010

The Journal of Chemical Physics

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Path-integral molecular dynamics (PIMD) simulations with an empirical interaction potential have been used to determine the experimental equilibrium structure of solid nitromethane at 4.2 and 15 K. By comparing the time-averaged molecular structure determined in a PIMD simulation to the calculated minimum-energy (zero-temperature) molecular structure, we have derived structural corrections that describe the effects of thermal motion. These corrections were subsequently used to determine the equilibrium structure of nitromethane from the experimental time-averaged structure. We find that the corrections to the intramolecular and intermolecular bond distances, as well as to the torsion angles, are quite significant, particularly for those atoms participating in the anharmonic motion of the methyl group. Our results demonstrate that simple harmonic models of thermal motion may not be sufficiently accurate, even at low temperatures, while molecular simulations employing more realistic potential-energy surfaces can provide important insight into the role and magnitude of anharmonic atomic motions.

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Section: Determination Of the Experimental Equilibrium Structure Of Smentioning

confidence: 99%

Determination of the experimental equilibrium structure of solid nitromethane using path-integral molecular dynamics simulations

Reilly

Habershon

Morrison

et al. 2010

The Journal of Chemical Physics

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“…Considering molecular systems specifically, much of the focus in previous work has been on single crystal neutron diffraction [10,11]. For example, hydrogen atoms (e.g.…”

Section: Neutron Crystallography Of Molecular Materialsmentioning

confidence: 99%

Neutron powder diffraction – new opportunities in hydrogen location in molecular and materials structure

Wilson¹,

Henry²,

Schmidtmann³

et al. 2014

Crystallography Reviews

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The potential of neutron powder diffraction in the location of hydrogen atoms in molecular materials and inorganic-molecular complexes is reviewed. Advances in instrumentation and data collection techniques that have made this field accessible are reviewed, along with a wide range of applications carried out by our collaboration investigating functional materials, hydrogen-containing minerals and molecular compounds. Some of the limitations in this area, particularly for molecular systems, are also addressed. IntroductionHydrogen is a key element whose functionality in inorganic material systems stretches from geochemical materials (e.g. clay minerals, cements), through key inorganic compounds (e.g. catalysts, co-ordination complexes and hydroxides/hydrates) and materials (e.g. polymers, hydrogen storage media, proton conductors/fuel cell components) to supramolecular and framework systems (e.g aluminosilicates, solvates and clathrates). The role of hydrogen in the structures (and hence derived applications) of these materials is thus of the utmost importance but one that, until recently, experimental methods generally failed to address, or could only do so in selected cases at great expense and considerable effort.Determination of the position of hydrogen in a material, whether it be a naturally occurring hydrate/hydroxide, a cement, a hydride/hydrogen storage material, a solvate or an organometallic compound has traditionally been difficult, time-consuming, expensive and imprecise, even where possible. However, knowledge of the distribution of hydrogen is central to understanding behaviours such as polymorphism, hydrogen bonding and three-dimensional structure definition, proton diffusion 2 pathways and levels of uptake in hydrogen storage materials, physical properties ranging from ferroelectricity to the elastic properties of polymers, and reaction mechanisms. Therefore the implementation and application of methodology that allows routine hydrogen position definition from readily available material (i.e. small easily synthesised quantities and in polycrystalline/small single crystal (≤50µm) form)is both of widespread application and key importance.In the work described here, development of the application of powder neutron diffraction methods in an optimised fashion to such materials is shown to have the capability to reveal structural information in a range of hydrogen-containing materials. A range of recent studies will be summarized, to illustrate the potential of this new capability. The powerful complementary use of both X-ray and computational methods with neutron powder diffraction in these studies will also be highlighted. The aim in this Review is not to provide a detailed account of the different materials studied, but to highlight the power of the methods of approach we have been systematically developing to access more accurate and different chemistry. It draws on a range of examples from our own collaborative work, which has recently focused on this theme [1].In this review, we have deli...

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“…

Crystal structure analysis by single-crystal X-ray diffraction (XRD) is the most commonly used method for determining whether Brønsted proton transfer or hydrogen-bonding take place in the solid state of organic materials. [1][2][3] Proton transfer is often identifiable by XRD, [1,2,[4][5][6][7][8][9] especially when analyzed in conjunction with structural indicators such as bond angles and bond lengths. [1,2,4,10] However, even with high-quality crystals an unequivocal determination of atomic hydrogen or proton positions is not always straightforward, particularly with systems involving proton disorder, temperature migration, or other unusual behavior.

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mentioning

confidence: 99%

“…[1,2,4,10] However, even with high-quality crystals an unequivocal determination of atomic hydrogen or proton positions is not always straightforward, particularly with systems involving proton disorder, temperature migration, or other unusual behavior. [8] Multi-component materials, for example, formed by solid-state preparation such as milling, or an inability to obtain suitable single crystals present additional limitations. Complementary experimental methods sensitive to proton and hydrogen positions become invaluable in such cases.Sometimes standard laboratory techniques such as vibrational spectroscopies provide the desired information [1,7] when the relevant spectral features are not too complex or broadened.…”

mentioning

confidence: 99%

“…Complementary experimental methods sensitive to proton and hydrogen positions become invaluable in such cases.Sometimes standard laboratory techniques such as vibrational spectroscopies provide the desired information [1,7] when the relevant spectral features are not too complex or broadened. More often, advanced techniques such as neutron diffraction, [1,8,10] in which proton position can be quantitatively determined, are employed. Examples for such systems are urea/phosphoric acid, [9,11,12] 4,4'-bipyridyl/benzene-1,2,4,5tetracarboxylic acid, [13] 4-methylpyridine/pentachlorophenol, [14] and benzoic acid.…”

mentioning

confidence: 99%

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Crystallography Aided by Atomic Core‐Level Binding Energies: Proton Transfer versus Hydrogen Bonding in Organic Crystal Structures

et al. 2011

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Ionisch oder H‐verbrückt? Der Transfer von Brønsted‐Protonen zu Stickstoffakzeptoren in organischen Kristallen verursacht starke Verschiebungen der Bindungsenergien des N1s‐Rumpfniveaus. Eine Untersuchung von 15 organischen Cokristall‐ und Salzsystemen zeigt, dass Röntgen‐Photoelektronenspektroskopie ergänzend zur Röntgenkristallographie genutzt werden kann, um Protonentransfer von Wasserstoffbrücken in kondensierter Materie zu unterscheiden (siehe Bild).

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The evolution of hydrogen atom parameters under changing external conditions by time-of-flight single crystal neutron diffraction

Cited by 20 publications

References 126 publications

Determination of the experimental equilibrium structure of solid nitromethane using path-integral molecular dynamics simulations

Determination of the experimental equilibrium structure of solid nitromethane using path-integral molecular dynamics simulations

Neutron powder diffraction – new opportunities in hydrogen location in molecular and materials structure

Crystallography Aided by Atomic Core‐Level Binding Energies: Proton Transfer versus Hydrogen Bonding in Organic Crystal Structures

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