Epoxidation of an α-tocopherol model compound, 2,2,5,7,8-pentamethylchroman-6-ol, with potassium superoxide; X-ray crystal structure of 4a,5;7,8-diepoxy-4a,7,8,8a-tetrahydro-8a-hydroxy-2,2,5,7,8-pentamethylchroman-6(5H)-one

1979 ◽  
pp. 105-106 ◽  
Author(s):  
Mitsuyoshi Matsuo ◽  
Shigenobu Matsumoto ◽  
Yoichi Iitaka ◽  
Akira Hanaki ◽  
Toshihiko Ozawa
Keyword(s):  
Crystal Structure ◽  
Model Compound ◽  
X Ray ◽  
Potassium Superoxide

Zur Struktur und Komplexchemie von Phosphinoderivaten des 5-Methoxy-2(5H)-furanons / Structure and Coordination Chemistry of Phosphino Derivatives of 5-Methoxy-2(5H)-furanon

1980 ◽  
Vol 35 (9) ◽  
pp. 1075-1082 ◽  
Author(s):  
D. Fenske ◽  
H. Prokscha ◽  
P. Stock ◽  
H. J. Becher
Keyword(s):  
Crystal Structure ◽  
Coordination Chemistry ◽  
Structure Analysis ◽  
Model Compound ◽  
Crystal Structure Analysis ◽  
X Ray ◽  
Derivatives Of ◽  
Cl Atoms ◽  
Cl Atom ◽  
Similar Complex

With R2PSi(CH3)3 (R = C6H5, i-C3H7, t-C4H9) one Cl atom of 3,4-dichlor-5-methoxy-2(5 H)-furanon (1) is substituted by the R2P group. An x-ray crystal structure analysis of the phosphino derivative with R = C6H5 (2) it has shown that of the two Cl atoms in 1 only the β-position (to C= O) is substituted. The coordination chemistry of 2 and its bis- (diphenylphosphino) derivative (3) is studied by preparation of the compounds 2 · Mo(CO)5 and 3 · Mo(CO)4. With PdCl2 · 2 C6H5CN (2) gives a dinuclear complex [2 · PdCl2]2, with bridging Cl atoms. The structure is established by a comparison with the similar complex of PdCl2 and 2-chloro-diphenylphosphino-maleic acid dimethylestor, which was synthe­sized as a model compound and studied by x-ray crystal structure analysis.

Effect of chain ends on the structure of aramid oligomers

2008 ◽  
Vol 86 (1) ◽  
pp. 7-19 ◽  
Author(s):  
Hakim Mehenni ◽  
Hélène Guillou ◽  
Christian Tessier ◽  
Josée Brisson
Keyword(s):  
Crystal Structure ◽  
Crystal Structures ◽  
Model Compound ◽  
Dimethyl Formamide ◽  
X Ray Diffraction ◽  
Aromatic Rings ◽  
X Ray ◽  
Internal Distribution ◽  
Diffraction Patterns ◽  
Additional Form

Synthesis, X-ray diffraction, and Fourier transform infrared spectroscopy of aliphatic–aromatic aramid oligomers are reported with the aim of shedding light on the effect of end-chain substituent on the morphology and structure of poly(para-phenylene terephthalamide) or PPTA. Three types of X-ray powder diffraction patterns were observed: one similar to that of PPTA form I, one similar to that of PPTA form II, and an additional form never reported. Some compounds, differing by their internal distribution of amide–aromatic rings, adopt two different crystal structures, whereas compounds having the same internal amide–aromatic arrangements, but differing by the nature of the end-groups, can adopt the same crystal structure. This clearly shows that both factors influence the packing adopted by the chains. Single-crystal structures of two polymorphs of a nitro-terminated model compound were resolved; both forms incorporate dimethyl formamide, and both show completely different packing. Infrared amide I and II band positions of most studied compounds match those observed for PPTA forms I or II, indicating that they exhibit planar hydrogen bonded sheets of molecules.Key words: aramid, crystal structure, poly(para-phenylene terephtalamide).

Colouring matters of Australian plants. XXII. Ventilagone: crystal structure and an approach to synthesis

1980 ◽  
Vol 33 (2) ◽  
pp. 303 ◽  
Author(s):  
RG Cooke ◽  
A Liu ◽  
CL Raston ◽  
AH White
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Least Squares ◽  
Title Compound ◽  
Model Compound ◽  
X Ray Diffraction ◽  
Compound A ◽  
X Ray ◽  
Naturally Occurring

The crystal structure of the title compound, a naturally occurring tricyclic quinone, C16H16O5, has been found to be (1R*,3S*)-7,10- dihydroxy-1,3,8-trimethyl-3,4,6,9-tetrahydro-1H-naphtho[2,3-c]-pyran- 6,9-dione by single-crystal X-ray diffraction methods at 295(1) K and refined by least squares to a residual of 0.033 for 1143 'observed' reflections. Crystals are monoclinic, P21, a 8.346(8), b 16.79(2), c 4.911(5)Ǻ, β 101.17(8)°, Z 2. The molecule is shown to have the cis configuration. As an approach to the synthesis of the pigment the model compound 5-chloro-8-methoxy-1,3-dimethylisochroman has been prepared and the two racemic forms have been separated and characterized.

A study on α-RuCl3 crystal structure by scanning tunneling microscopy

1989 ◽  
Vol 47 ◽  
pp. 30-31
Author(s):  
H.-J. Cantow ◽  
H. Hillebrecht ◽  
S. Magonov ◽  
H. W. Rotter ◽  
G. Thiele
Keyword(s):  
Crystal Structure ◽  
Density Distribution ◽  
Scanning Tunneling Microscopy ◽  
Electron Density ◽  
Structure Determination ◽  
Electron Density Distribution ◽  
Scanning Tunneling ◽  
Monoclinic Space Group ◽  
Tunneling Microscopy ◽  
X Ray

From X-ray analysis, the conclusions are drawn from averaged molecular informations. Thus, limitations are caused when analyzing systems whose symmetry is reduced due to interatomic interactions. In contrast, scanning tunneling microscopy (STM) directly images atomic scale surface electron density distribution, with a resolution up to fractions of Angstrom units. The crucial point is the correlation between the electron density distribution and the localization of individual atoms, which is reasonable in many cases. Thus, the use of STM images for crystal structure determination may be permitted. We tried to apply RuCl3 - a layered material with semiconductive properties - for such STM studies. From the X-ray analysis it has been assumed that α-form of this compound crystallizes in the monoclinic space group C2/m (AICI3 type). The chlorine atoms form an almost undistorted cubic closed package while Ru occupies 2/3 of the octahedral holes in every second layer building up a plane hexagon net (graphite net). Idealizing the arrangement of the chlorines a hexagonal symmetry would be expected. X-ray structure determination of isotypic compounds e.g. IrBr3 leads only to averaged positions of the metal atoms as there exist extended stacking faults of the metal layers.

X-ray Crystal Structure of ?9-THC-tosylate

Planta Medica ◽  
2008 ◽  
Vol 74 (03) ◽  
Author(s):  
W Gul ◽  
P Carvalho ◽  
D Slade ◽  
M Avery ◽  
JR Duchek ◽  
...  
Keyword(s):  
Crystal Structure ◽  
X Ray

Crystal structure of an inclusion complex between chiral monoaza-15-crown-5 and S(–)-1-phenyl-ethyl ammonium percholorate

2003 ◽  
Vol 218 (5) ◽  
Author(s):  
Süheyla Özbey ◽  
F. B. Kaynak ◽  
M. Toğrul ◽  
N. Demirel ◽  
H. Hoşgören
Keyword(s):  
Crystal Structure ◽  
Inclusion Complex ◽  
Single Crystal ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
New Type

AbstractA new type of inclusion complex, S(–)-1 phenyl ethyl ammonium percholorate complex of R-(–)-2-ethyl - N - benzyl - 4, 7, 10, 13 - tetraoxa -1- azacyclopentadecane, has been prepared and studied by NMR, IR and single crystal X-ray diffraction techniques. The compound crystallizes in space group

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