Hydroxyl-directed reduction of β-hydroxycycloalkanones as a stereoselective route to 1,3-diols: X-ray crystal structure and structural features of (1R*,2R*,6S*)-2-[hydroxy(phenyl)methyl]cyclopentanol

1995 ◽  
pp. 379-383 ◽  
Author(s):  
Stephen H. J. Thompson ◽  
Mary F. Mahon ◽  
Kieran C. Molloy ◽  
Michael S. Hadley ◽  
Timothy Gallagher
Keyword(s):  
Crystal Structure ◽  
Structural Features ◽  
X Ray

New Ternary Phosphide La7Pd17P12: Preparation and Crystal Structure

2002 ◽  
Vol 57 (12) ◽  
pp. 1409-1413 ◽  
Author(s):  
S. Budnyk ◽  
Yu. Prots ◽  
Yu. Kuz’ma ◽  
Yu. Grin
Keyword(s):  
Crystal Structure ◽  
Temperature Region ◽  
Large Family ◽  
Structural Features ◽  
Structural Motif ◽  
Crystal Data ◽  
Monoclinic Structure ◽  
X Ray ◽  
Data Space ◽  
Metal Ratio

The title compound was prepared from elements by sintering in the temperature region between 1073 and 1473 K. The monoclinic structure of La7Pd17P12 was solved and refined from X-ray single crystal data: space group C2/m, a = 24.519(1), b = 4.0859(5), c = 13.6106(8)Å , β = 112.129(3)°, Z = 2, RF = 0.025 for 1065 unique of 4877 measured reflections and 112 refined parameters. Main structural motif of the new phosphide are condensed blocks of trigonal prisms around phosphorus atoms connected to infinite chains via lanthanum atoms. The structural features of La7Pd17P12 are discussed in comparison with some representatives of a large family of structures with metal / non-metal ratio close to 2 : 1.

The Transition Metal-rich Orthophosphate Arrojadite with Special Structural Features

2010 ◽  
Vol 65 (12) ◽  
pp. 1427-1433 ◽  
Author(s):  
Christoph Kallfaß ◽  
Constantin Hoch ◽  
Hermann Schier ◽  
Arndt Simon ◽  
Helmut Schuber
Keyword(s):  
Crystal Structure ◽  
Transition Metal ◽  
Single Crystal ◽  
Structural Features ◽  
Nickel Plate ◽  
Single Crystal Diffraction ◽  
X Ray ◽  
Different Types ◽  
New Feature

The crystal structure of the transition metal-rich orthophosphate mineral arrojadite was reexamined, and the disorder phenomena were analyzed applying modern X-ray single-crystal diffraction and refinement methods on samples from Nickel Plate (USA) and Hagendorf (Germany). As a new feature of the arrojadite structure, two different types of channels oriented along [010] are described. The occupancy of the atomic positions inside these channels have been elucidated.

8-(Dimethylamino)naphthylcopper(I), a novel stable organocopper compound with unusual structural features. Its synthesis, crystal structure (X-ray), and reactivity

1987 ◽  
Vol 325 (1-2) ◽  
pp. 293-309 ◽  
Author(s):  
Erik Wehman ◽  
Gerard van Koten ◽  
Martin Knotter ◽  
Hans Spelten ◽  
Dick Heijdenrijk ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Structural Features ◽  
X Ray

scholarly journals Crystal structure solution of an elusive polymorph of Dibenzylsquaramide

2013 ◽  
Vol 28 (S2) ◽  
pp. S470-S480 ◽  
Author(s):  
Anna Portell ◽  
Xavier Alcobé ◽  
Latévi M. Lawson Daku ◽  
Radovan Černý ◽  
Rafel Prohens
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Structural Features ◽  
Powder Diffraction Data ◽  
Asymmetric Unit ◽  
X Ray ◽  
The Third ◽  
Group Assignment ◽  
Structure Solution

The crystal structure of the third polymorph of dibenzylsquaramide (Portell, A. et al., 2009), (fig. 1) has been determined from laboratory X-ray powder diffraction data by means of direct space methods using the computing program FOX. (Favre-Nicolin and Černý, 2002) The structure resolution has not been straightforward due to several difficulties on the indexing process and in the space group assignment. The asymmetric unit contains two different conformers, which has implied an additional difficulty during the Rietveld (Rietveld, 1969) refinement. All these issues together with particular structural features of disquaramides are discussed.

Crystal Structure Explains Crystal Habit for the Antiviral Drug Rimantadine Hydrochloride

2014 ◽  
Vol 69 (7) ◽  
pp. 823-828 ◽  
Author(s):  
Anatoly Mishnev ◽  
Dmitrijs Stepanovs
Keyword(s):  
Crystal Structure ◽  
Symmetry Axis ◽  
Antiviral Drug ◽  
Structural Features ◽  
Unit Cell ◽  
Crystal Habit ◽  
Maximal Dimension ◽  
X Ray ◽  
Rimantadine Hydrochloride ◽  
Inner Channel

The crystal structure of the antiviral drug rimantadine hydrochloride, C12H22N+ Cl−, has been elucidated by a single-crystal X-ray structure analysis. The structure consists of 1-(1- adamantyl)ethanamine (rimantadinium) cations and chloride anions. The Cl− anions link the rimantadinium cations via N-H...Cl hydrogen bonds into infinite rectangular chord-like structural units with charged groups in the inner channel and aliphatic groups on the surface, and oriented along the unit cell c axis. In contrast to strong electrostatic and hydrogen bonding inner interactions the chords in the crystal are held together by weak van der Waals forces only. A two-fold symmetry axis passes through the center of the chord. By indexing of the crystal faces it has been shown that the maximal dimension of the needle-like crystals coincides with the direction of the unit cell c axis. These structural features explain the crystal habit and the anisotropy of the mechanical properties of rimantadine hydrochloride crystals observed upon slicing and cleavage.

scholarly journals Preparation and Crystal Structure of a Rhenium Analogue of the Cationic Renal Agent, Tc-99m Diaminocyclohexane

2000 ◽  
Vol 7 (3) ◽  
pp. 141-145 ◽  
Author(s):  
Luigi G. Marzilli ◽  
Lory Hansen ◽  
Andrew Taylor ◽  
Rene Lachicotte
Keyword(s):  
Crystal Structure ◽  
Plasma Flow ◽  
Structural Parameters ◽  
Renal Plasma Flow ◽  
Chemical Study ◽  
Structural Features ◽  
Racemic Mixture ◽  
X Ray ◽  
X Ray Crystallography ◽  
Renal Agent

We report here a chemical study on a Re analogue of one of the few cationic Tc-99m tracers previously investigated as an agent for effective renal plasma flow (ERPF) measurement. Cationic Tc-99m tracers have the potential for overcoming problems associated with common anionic Tc-99m tracers in patients who have developed a uremic state. The Tc-99m-DACH tracer, prepared from 1,2-diaminocyclohexane (1,2-DACH), is the only cationic renal agent tested in humans and has seven possible isomers. The complex isolated from the reaction of the racemic mixture, (±)-trans-1,2-DACH, and ReIO2(PPh3)2 after conversion to the BPh4- salt was found by X-ray crystallography to be the meso isomer, trans-[ReO2 (trans-R,R-1,2-DACH)(trans-S,S-l,2-DACH)][BPh4]·MeOH·2H2O (1). The structural parameters for 1 are normal. The complex is highly symmetrical, suggesting that the analogous meso Tc-99m-DACH agent is also symmetrical. Studies of other Tc-99m-DACH agents that were made from cis-1,2-DACH or individual trans-1,2-DACH enantiomers show that the biodistribution is not very dependent on the starting 1,2-DACH ligand stereochemistry; these agents must be less symmetrical than the meso Tc-99m-DACH agent analogue of 1. Thus, the overall charge and lipophilicity (similar for all Tc-99m-DACH isomers) exert a greater influence on biodistribution than the specific structural features of the different Tc-99m-DACH isomers.

scholarly journals The structure of kaliophilite KAlSiO4, a long-lasting crystallographic problem

IUCrJ ◽  
2020 ◽  
Vol 7 (6) ◽  
pp. 1070-1083 ◽  
Author(s):  
Enrico Mugnaioli ◽  
Elena Bonaccorsi ◽  
Arianna E. Lanza ◽  
Erik Elkaim ◽  
Virginia Diez-Gómez ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Rietveld Method ◽  
Structural Features ◽  
Unit Cell ◽  
X Ray Diffraction ◽  
Channel System ◽  
X Ray ◽  
Cell Parameters ◽  
Peak Broadening ◽  
Structure Solution

Kaliophilite is a feldspathoid mineral found in two Italian magmatic provinces and represents one of the 12 known phases with composition close to KAlSiO4. Despite its apparently simple formula, the structure of this mineral revealed extremely complex and resisted structure solution for more than a century. Samples from the Vesuvius–Monte Somma and Alban Hills volcanic areas were analyzed through a multi-technique approach, and finally the crystal structure of kaliophilite was solved using 3D electron diffraction and refined against X-ray diffraction data of a twinned crystal. Results were also ascertained by the Rietveld method using synchrotron powder intensities. It was found that kaliophilite crystallizes in space group P3 with unit-cell parameters a = 27.0597 (16), c = 8.5587 (6) Å, V = 5427.3 (7) Å3 and Z = 54. The kaliophilite framework is a variant of the tridymite topology, with alternating SiO4 and AlO4 tetrahedra forming sheets of six-membered rings (63 nets), which are connected along [001] by sharing the apical oxygen atoms. Considering the up (U) and down (D) orientations of the linking vertex, kaliophilite is the first framework that contains three different ring topologies: nine (1-3-5) (UDUDUD) rings, six (1-2-3) (UUUDDD) rings and twelve (1-2-4) (UUDUDD) rings. This results in a relatively open (19.9 tetrahedra nm−3) channel system with multiple connections between the double six-ring cavities. Such a framework requires a surprisingly large unit cell, 27 times larger than the cell of kalsilite, the simplest phase with the same composition. The occurrence of some Na for K substitution (3–10%) may be related to the characteristic structural features of kaliophilite. Micro-twinning, pseudo-symmetries and anisotropic hkl-dependent peak broadening were also detected, and they may account for the elusive character of the kaliophilite crystal structure.

Synthesis and crystal structure of C2/c Ca(Co,Mg)Si2O6 pyroxenes: effect of the cation substitution on cell volume

2017 ◽  
Vol 81 (5) ◽  
pp. 1129-1139 ◽  
Author(s):  
C. Gori ◽  
M. Tribaudino ◽  
L. Mantovani ◽  
G. D. Gatta ◽  
D. Delmonte ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Comparative Analysis ◽  
Diffraction Data ◽  
Divalent Cations ◽  
Structural Features ◽  
Cation Substitution ◽  
X Ray Diffraction ◽  
Synthesis And Crystal Structure ◽  
X Ray ◽  
Experimental Findings

AbstractA series of clinopyroxenes along the CaMgSi2O6–CaCoSi2O6 join was synthesized by quenching from melts at 1500°C and subsequent annealing at 1250°C (at 0.0001 GPa). This protocol proved to be the most effective to obtain homogenous, impurity-free and stoichiometric pyroxenes. Electron microprobe analyses in energy dispersive mode were conducted and single-crystal X-ray diffraction data were collected on Ca (CoxMg1-x)Si2O6 pyroxenes with x = 0.2, 0.4, 0.5, 0.6. Effects of cation substitution at the M1 site are described. The experimental findings of this study allow us to extend the comparative analysis of the structural features of pyroxenes with divalent cations at the M1 and M2 sites.

Crystal and solution structure of a pendant-armed macrocyclic complex of palladium(II)

1994 ◽  
Vol 72 (6) ◽  
pp. 1525-1532 ◽  
Author(s):  
B. Chak ◽  
A. McAuley ◽  
T.W. Whitcombe
Keyword(s):  
Crystal Structure ◽  
Solution Structure ◽  
Structural Features ◽  
Macrocyclic Complex ◽  
Chelating Ligands ◽  
Sulphur Atom ◽  
Positive Interaction ◽  
Range Interaction ◽  
X Ray ◽  
Long Range Interaction

The synthesis and X-ray crystal structure of [Pd)py2[9]aneN2S)](BF4)2 (py2[9]aneN2S = 1-thia-4,7-bis(pyridylmethyl)diaza-cyclononane) (P21/n,a = 10.233(4) Å, b = 11.484(5) Å, c = 19.913(6) Å, β = 94.03(4)°, V = 2334(2) Å3, R = 0.0705, Rw = 0.0759 ) are presented. The crystal structure indicates a long range interaction (2.92 Å) between the planar palladium and the apical sulphur atom. Although this distance is longer than the value for a Pd—S bond observed normally there is evidence for a net positive interaction provided by the solution structure as determined by NMR spectroscopy. Comparative analysis of the structural features exhibited by this complex with similar nine-membered chelating ligands emphasizes the presence of an axial Pd—S bond.

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