scholarly journals Redetermination of β-Ba(PO3)2

2014 ◽  
Vol 70 (2) ◽  
pp. i7-i7 ◽  
Author(s):  
Matthias Weil
Keyword(s):  
Bond Length ◽  
Coordination Polyhedron ◽  
Structure Determination ◽  
Length Distribution ◽  
Anisotropic Displacement Parameters ◽  
The Absolute ◽  
Bond Length Distribution ◽  
Absolute Structure ◽  
Atomic Coordinates

In comparison with the previous structure determination of the β-modification of bariumcatena-polyphosphate that was based on Weissenberg film data [Grenieret al.(1967).Bull. Soc. Fr. Minéral. Cristallogr.90, 24–31], the current CCD-data-based redetermination reveals all atoms with anisotropic displacement parameters, standard uncertainties for the atomic coordinates, and the determination of the absolute structure. Moreover, a much higher accuracy in terms of the bond-length distribution for the polyphosphate chain, with two shorter and two longer P—O distances, was achieved. The structure consists of polyphosphate chains extending parallel to [100] with a periodicity of two PO4tetrahedra. The Ba2+cations are located between the chains and are surrounded by ten O atoms in the form of a distorted coordination polyhedron, with Ba—O distances ranging from 2.765 (3) to 3.143 (3) Å, also reflecting the higher precision of the current redetermination.

scholarly journals Absolute structure determination of compounds with axial and planar chirality using the crystalline sponge method

2015 ◽  
Vol 6 (7) ◽  
pp. 3765-3768 ◽  
Author(s):  
Shota Yoshioka ◽  
Yasuhide Inokuma ◽  
Manabu Hoshino ◽  
Takashi Sato ◽  
Makoto Fujita
Keyword(s):  
Structure Determination ◽  
Asymmetric Syntheses ◽  
Planar Chirality ◽  
The Absolute ◽  
Absolute Structure

The absolute structure determination of compounds with axial and planar chirality obtained by recently developed asymmetric syntheses was achieved using the crystalline sponge method without using any reference compounds or synthetic modifications.

Chiral Crystalline Sponges for the Absolute Structure Determination of Chiral Guests

2017 ◽  
Vol 139 (33) ◽  
pp. 11341-11344 ◽  
Author(s):  
KaKing Yan ◽  
Ritesh Dubey ◽  
Tatsuhiko Arai ◽  
Yasuhide Inokuma ◽  
Makoto Fujita
Keyword(s):  
Structure Determination ◽  
The Absolute ◽  
Absolute Structure

The use of Mo Kα radiation in the assignment of the absolute configuration of light-atom molecules; the importance of high-resolution data

2014 ◽  
Vol 70 (4) ◽  
pp. 660-668 ◽  
Author(s):  
Eduardo C. Escudero-Adán ◽  
Jordi Benet-Buchholz ◽  
Pablo Ballester
Keyword(s):  
High Resolution ◽  
Crystal Structures ◽  
Structure Determination ◽  
Great Majority ◽  
Data Sets ◽  
Light Atom ◽  
High Resolution Data ◽  
The Absolute ◽  
Absolute Structure

Recent studies have confirmed the usefulness of the Hooft and Parsons methodologies for determination of the absolute crystal structures of enantiopure light-atom compounds using CuKα radiation. While many single-crystal diffractometers used for small-molecule structure determination are equipped with molybdenum anodes, use of data from such instruments for the absolute structure determination of light-atom crystal structures is rarely documented and has often been found to be unsuccessful. The Hooft and Parsons methodologies have been applied to 44 data sets obtained from single crystals containing light-atom molecules of known chirality using Mo Kαradiation. Several factors influencing the calculation of accurate and precise values for the Hooft and Parsons parameters obtained from these data sets have been identified, the inclusion of high-resolution diffraction data being particularly important. The correct absolute structure was obtained in all cases, with the standard uncertainties of the final absolute structure parameters below 0.1 for the great majority.

On measuring the size of distortions in coordination polyhedra

2006 ◽  
Vol 62 (4) ◽  
pp. 692-694 ◽  
Author(s):  
I. David Brown
Keyword(s):  
Bond Length ◽  
Coordination Polyhedron ◽  
Length Distribution ◽  
Higher Moments ◽  
Coordination Polyhedra ◽  
The Third ◽  
Suitable Index ◽  
Average Bond ◽  
Bond Length Distribution ◽  
Unique Index

There is no unique index that measures the size of the distortion found in a coordination polyhedron because different indices can result in a different ordering depending on the mode of the distortion (i.e. the third and higher moments of the bond-length distribution). This paper proposes the increase in the average bond length as a suitable index as this is directly related to the increase in volume of the coordination polyhedron and hence of the unit cell. Some examples are discussed.

scholarly journals Redetermination of theγ-form of tellurium dioxide

IUCrData ◽  
2017 ◽  
Vol 2 (12) ◽  
Author(s):  
Matthias Weil
Keyword(s):  
Crystal Structure ◽  
Diffraction Data ◽  
Structure Determination ◽  
Three Dimensional ◽  
X Ray Diffraction ◽  
X Ray ◽  
Accuracy And Precision ◽  
Anisotropic Displacement Parameters ◽  
Absolute Structure

The crystal structure of γ-TeO2was redetermined on the basis of single-crystal X-ray diffraction data. The previous structure determination of this modification was based on laboratory powder X-ray diffraction data [Champarnaud-Mesjardet al.(2000).J. Phys. Chem. Solids,61, 1499–1507]. The current redetermination revealed all atoms with anisotropic displacement parameters, accompanied with a much higher accuracy and precision in terms of bond lengths and angles, and the determination of the absolute structure. The crystal structure consists of TeO4bisphenoids that combine through corner-sharing of all their oxygen atoms into a three-dimensional framework.

Polymorphism, polar morphology and absolute structure determination of 4-iodo-4′-nitrobiphenyl (INBP)

CrystEngComm ◽  
2010 ◽  
Vol 12 (4) ◽  
pp. 1252-1262 ◽  
Author(s):  
Gaël Labat ◽  
Norwid-Rasmus Behrnd ◽  
Gaëtan Couderc ◽  
Michel Bonin ◽  
Julius Tsuwi ◽  
...  
Keyword(s):  
Structure Determination ◽  
Absolute Structure
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