scholarly journals Full crystal structure, hydrogen bonding and spectroscopic, mechanical and thermodynamic properties of mineral uranopilite

RSC Advances ◽  
2020 ◽  
Vol 10 (53) ◽  
pp. 31947-31960 ◽  
Author(s):  
Francisco Colmenero ◽  
Jakub Plášil ◽  
Vicente Timón ◽  
Jiří Čejka
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Thermodynamic Properties ◽  
Poor Quality ◽  
X Ray Diffraction ◽  
Uranyl Sulfate ◽  
X Ray ◽  
The Poor

The determination of the full crystal structure of the uranyl sulfate mineral uranopilite, including the positions of the H atoms in the corresponding unit cell, has not been feasible to date due to the poor quality of its X-ray diffraction pattern.

Solvothermal Synthesis and Crystal Structure Determination of Tris- (ethyleneamine-ammonium) Tetraselenoantimonat: Non-Centrosymmetry Mediated by an Extended Unusual N-H···N Hydrogen Bonded Network?

1998 ◽  
Vol 53 (10) ◽  
pp. 1144-1148 ◽  
Author(s):  
Frank Wendland ◽  
Christian Näther ◽  
Michael Schur ◽  
Wolfgang Bensch
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Solvothermal Synthesis ◽  
Amino Nitrogen ◽  
X Ray Diffraction ◽  
Synthesis And Crystal Structure ◽  
X Ray ◽  
Ammonium Hydrogen ◽  
Solvothermal Conditions

AbstractThe title compound has been synthesized under solvothermal conditions by the reaction of elemental chromium, antimony and selenium in a solution of 40% 1,2-ethanediamine (en) in methanol. The crystal structure consists of tetrahedral SbSe43- anions which are connected by monoprotonated 1,2-ethanediamine (enH+) cations via N-H--Se hydrogen bonding. The enH+ cations are joined via strong N-H -N hydrogen bonds between the ammonium hydrogen and the amino nitrogen atom forming four distinct chains, each built up of three crystallographically independent enH+ cations. Two of these chains are running parallel to [100], the other two are parallel to [010]. Based on this arrangement different centrosymmetric or non-centrosymmetric hydrogen bonding patterns are possible, but only in one chain the sequence of NH2 and NH3+ groups was determined by X-ray diffraction

Crystal structure of defect-containing semiconductor nanocrystals – an X-ray diffraction study

2009 ◽  
Vol 42 (4) ◽  
pp. 660-672 ◽  
Author(s):  
Maja Buljan ◽  
Uroš V. Desnica ◽  
Nikola Radić ◽  
Goran Dražić ◽  
Zdeněk Matěj ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Profile Analysis ◽  
Semiconductor Nanocrystals ◽  
X Ray Diffraction ◽  
Structure Quality ◽  
X Ray ◽  
Self Organized ◽  
Full Profile

Defects of crystal structure in semiconductor nanocrystals embedded in an amorphous matrix are studied by X-ray diffraction and a full-profile analysis of the diffraction curves based on the Debye formula. A new theoretical model is proposed, describing the diffraction from randomly distributed intrinsic and extrinsic stacking faults and twin blocks in the nanocrystals. The application of the model to full-profile analysis of experimental diffraction curves enables the determination of the concentrations of individual defect types in the nanocrystals. The method has been applied for the investigation of self-organized Ge nanocrystals in an SiO2matrix, and the dependence of the structure quality of the nanocrystals on their deposition and annealing parameters was obtained.

Crystal structure determination of the conformation of two bicyclo[3.3.1]nonan-ones

1985 ◽  
Vol 63 (6) ◽  
pp. 1166-1169 ◽  
Author(s):  
John F. Richardson ◽  
Ted S. Sorensen
Keyword(s):  
Crystal Structure ◽  
Direct Methods ◽  
Chair Conformation ◽  
Molecular Structures ◽  
Boat Conformation ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
Final Agreement

The molecular structures of exo-7-methylbicyclo[3.3.1]nonan-3-one, 3, and the endo-7-methyl isomer, 4, have been determined using X-ray-diffraction techniques. Compound 3 crystallizes in the space group [Formula: see text] with a = 15.115(1), c = 7.677(2) Å, and Z = 8 while 4 crystallizes in the space group P21 with a = 6.446(1), b = 7.831(1), c = 8.414(2) Å, β = 94.42(2)°, and Z = 2. The structures were solved by direct methods and refined to final agreement factors of R = 0.041 and R = 0.034 for 3 and 4 respectively. Compound 3 exists in a chair–chair conformation and there is no significant flattening of the chair rings. However, in 4, the non-ketone ring is forced into a boat conformation. These results are significant in interpreting what conformations may be present in the related sp2-hybridized carbocations.

scholarly journals Exploring the Structural Chemistry of Pyrophosphoramides: N,N′,N″,N‴-Tetraisopropylpyrophosphoramide

Chemistry ◽  
2021 ◽  
Vol 3 (1) ◽  
pp. 149-163
Author(s):  
Duncan Micallef ◽  
Liana Vella-Zarb ◽  
Ulrich Baisch
Keyword(s):  
Crystal Structure ◽  
Mass Spectrometry ◽  
Nuclear Magnetic Resonance ◽  
Hydrogen Bonding ◽  
Nmr Spectroscopy ◽  
Ir Spectroscopy ◽  
Room Temperature ◽  
Intermolecular Hydrogen Bonding ◽  
X Ray Diffraction ◽  
X Ray

N,N′,N″,N‴-Tetraisopropylpyrophosphoramide 1 is a pyrophosphoramide with documented butyrylcholinesterase inhibition, a property shared with the more widely studied octamethylphosphoramide (Schradan). Unlike Schradan, 1 is a solid at room temperature making it one of a few known pyrophosphoramide solids. The crystal structure of 1 was determined by single-crystal X-ray diffraction and compared with that of other previously described solid pyrophosphoramides. The pyrophosphoramide discussed in this study was synthesised by reacting iso-propyl amine with pyrophosphoryl tetrachloride under anhydrous conditions. A unique supramolecular motif was observed when compared with previously published pyrophosphoramide structures having two different intermolecular hydrogen bonding synthons. Furthermore, the potential of a wider variety of supramolecular structures in which similar pyrophosphoramides can crystallise was recognised. Proton (1H) and Phosphorus 31 (31P) Nuclear Magnetic Resonance (NMR) spectroscopy, infrared (IR) spectroscopy, mass spectrometry (MS) were carried out to complete the analysis of the compound.

The molecular and crystal structure of [Pt(diethylenetriamine)(guanosine)](ClO4)2

1979 ◽  
Vol 57 (1) ◽  
pp. 57-61 ◽  
Author(s):  
R. Melanson ◽  
F. D. Rochon
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Least Squares ◽  
Platinum Atom ◽  
X Ray Diffraction ◽  
Orthorhombic Space Group ◽  
X Ray ◽  
R Factor ◽  
Square Planar ◽  
Coordination Plane

The crystal structure of [Pt(diethylenetriamine)(guanosine)](ClO4)2 has been determined by X-ray diffraction. The crystals are orthorhombic, space group P212121, with a = 12.486(6), b = 13.444(7), c = 14.678(11) Å, and Z = 4. The structure was refined by block-diagonal least-squares analysis to a conventional R factor of 0.050 and a weighted Rw = 0.045.The coordination around the platinum atom is square planar. Guanosine is bonded to platinum through N(7). The purine planar ring makes an angle of 62.7° with the platinum coordination plane. The structure is stabilized by hydrogen bonding.

The crystal structure of gatehouseite

2011 ◽  
Vol 75 (6) ◽  
pp. 2823-2832
Author(s):  
P. Elliott ◽  
A. Pring
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Three Dimensional ◽  
Direct Methods ◽  
Chemical Analyses ◽  
X Ray Diffraction ◽  
X Ray ◽  
Manganese Phosphate ◽  
Phosphate Mineral ◽  
Unit Formula

AbstractThe crystal structure of the manganese phosphate mineral gatehouseite, ideally Mn52+(PO4)2(OH)4, space group P212121, a = 17.9733(18), b = 5.6916(11), c = 9.130(4) Å, V= 933.9(4) Å3, Z = 4, has been solved by direct methods and refined from single-crystal X-ray diffraction data (T = 293 K) to an R index of 3.76%. Gatehouseite is isostructural with arsenoclasite and with synthetic Mn52+(PO4)2(OH)4. The structure contains five octahedrally coordinated Mn sites, occupied by Mn plus very minor Mg with observed <Mn—O> distances from 2.163 to 2.239 Å. Two tetrahedrally coordinated P sites, occupied by P, Si and As, have <P—O> distances of 1.559 and 1.558 Å. The structure comprises two types of building unit. A strip of edge-sharing Mn(O,OH)6 octahedra, alternately one and two octahedra wide, extends along [010]. Chains of edge- and corner-shared Mn(O,OH)6 octahedra coupled by PO4 tetrahedra extend along [010]. By sharing octahedron and tetrahedron corners, these two units form a dense three-dimensional framework, which is further strengthened by weak hydrogen bonding. Chemical analyses by electron microprobe gave a unit formula of (Mn4.99Mg0.02)Σ5.01(P1.76Si0.07(As0.07)Σ2.03O8(OH)3.97.

scholarly journals Magnetically Oriented Powder Crystal to Indexing and Structure Determination

2014 ◽  
Vol 70 (a1) ◽  
pp. C1560-C1560
Author(s):  
Fumiko Kimura ◽  
Wataru Oshima ◽  
Hiroko Matsumoto ◽  
Hidehiro Uekusa ◽  
Kazuaki Aburaya ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Crystal Lattice ◽  
Powder Diffraction ◽  
Diffraction Method ◽  
Lattice Parameters ◽  
X Ray Diffraction ◽  
X Ray ◽  
Crystal Lattice Parameters

In pharmaceutical sciences, the crystal structure is of primary importance because it influences drug efficacy. Due to difficulties of growing a large single crystal suitable for the single crystal X-ray diffraction analysis, powder diffraction method is widely used. In powder method, two-dimensional diffraction information is projected onto one dimension, which impairs the accuracy of the resulting crystal structure. To overcome this problem, we recently proposed a novel method of fabricating a magnetically oriented microcrystal array (MOMA), a composite in which microcrystals are aligned three-dimensionally in a polymer matrix. The X-ray diffraction of the MOMA is equivalent to that of the corresponding large single crystal, enabling the determination of the crystal lattice parameters and crystal structure of the embedded microcrytals.[1-3] Because we make use of the diamagnetic anisotropy of crystal, those crystals that exhibit small magnetic anisotropy do not take sufficient three-dimensional alignment. However, even for these crystals that only align uniaxially, the determination of the crystal lattice parameters can be easily made compared with the determination by powder diffraction pattern. Once these parameters are determined, crystal structure can be determined by X-ray powder diffraction method. In this paper, we demonstrate possibility of the MOMA method to assist the structure analysis through X-ray powder and single crystal diffraction methods. We applied the MOMA method to various microcrystalline powders including L-alanine, 1,3,5-triphenyl benzene, and cellobiose. The obtained MOMAs exhibited well-resolved diffraction spots, and we succeeded in determination of the crystal lattice parameters and crystal structure analysis.

scholarly journals SPECTROSCOPIC METHODS TO DETERMINATION OF GEOTHITE IN KAOLINITE

2020 ◽  
Vol 17 (35) ◽  
pp. 303-314
Author(s):  
Marcelo Kehl; ; ; ; DE SOUZA ◽  
Marcos Antônio KLUNK ◽  
Soyane Juceli Siqueira XAVIER ◽  
Mohuli DAS ◽  
Sudipta DASGUPTA
Keyword(s):  
Spectroscopic Methods ◽  
Industrial Minerals ◽  
X Ray Diffraction ◽  
Simple Shape ◽  
X Ray ◽  
Spectroscopic Monitoring ◽  
Partial Release ◽  
Primary Minerals

One of the main contaminants of kaolinite, the iron, directly impacts quality in its commercial value. The spectroscopic monitoring, measured the depth of absorption of kaolinite, is compared with the literature in order to identify possible contaminants. The occurrence of kaolinite is due to the formation of primary minerals after the partial release of cations and silicon. This clay-mineral has a simple shape, with variable crystallographic imperfections, especially in the presence of iron, which replaces aluminum in the mineral chain, causing various structural disorganizations. The extraction of industrial minerals combined with geological studies, allows the development of new sources of energy, such as clay minerals, in particular kaolinite. Depending on the origin of the kaolinites, the presence of iron oxides in its structure, Fe2O3 and FeO(OH), are common. By comparing the results of spectroscopy (X-ray fluorescence, X-ray diffraction, RAMAN) and imaging using SEM-EDS, it was possible to identify kaolinite, with a higher determination coefficient, when the proportion of kaolinite reaches 60% or more in the mix. Kaolinite can be identified and quantified with a high correlation in the mixture from the sample absorption. Thus, the method has great potential to assist in quantifying and, consequently, in discriminating the quality of kaolinite.

scholarly journals Rubidium tetrafluoridobromate(III): redetermination of the crystal structure from single-crystal X-ray diffraction data

IUCrData ◽  
2019 ◽  
Vol 4 (11) ◽  
Author(s):  
Artem V. Malin ◽  
Sergei I. Ivlev ◽  
Roman V. Ostvald ◽  
Florian Kraus
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Single Crystals ◽  
Diffraction Data ◽  
Structure Type ◽  
X Ray Diffraction ◽  
X Ray ◽  
Square Planar ◽  
Atomic Coordinates

Single crystals of rubidium tetrafluoridobromate(III), RbBrF4, were grown by melting and recrystallizing RbBrF4 from its melt. This is the first determination of the crystal structure of RbBrF4 using single-crystal X-ray diffraction data. We confirmed that the structure contains square-planar [BrF4]− anions and rubidium cations that are coordinated by F atoms in a square-antiprismatic manner. The compound crystallizes in the KBrF4 structure type. Atomic coordinates and bond lengths and angles were determined with higher precision than in a previous report based on powder X-ray diffraction data [Ivlev et al. (2015). Z. Anorg. Allg. Chem. 641, 2593–2598].

Sign in / Sign up

Export Citation Format

Share Document