Regio- and Diastereoselective Synthesis and X-ray Structure Determination of (+)-2-Deoxyoryzalexin S from (+)-Podocarpic Acid. Structural Nonidentity with Its Nominal Natural Isolated Enantiomer

2012 ◽  
Vol 75 (11) ◽  
pp. 1944-1950 ◽  
Author(s):  
Francesca Leonelli ◽  
Valentina Latini ◽  
Andrea Trombetta ◽  
Gabriele Bartoli ◽  
Francesca Ceccacci ◽  
...  
Keyword(s):  
Structure Determination ◽  
Diastereoselective Synthesis ◽  
X Ray

The protonation of the ethylenediphosphinetetraacetate anion and the crystal structure of the bis (hydrogen bromide) of ethylenediphosphinetetraacetic acid

1981 ◽  
Vol 46 (12) ◽  
pp. 3063-3073 ◽  
Author(s):  
Jana Podlahová ◽  
Bohumil Kratochvíl ◽  
Vratislav Langer ◽  
Josef Šilha ◽  
Jaroslav Podlaha
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Structure Determination ◽  
Free Acid ◽  
Hydrogen Bromide ◽  
Carboxyl Groups ◽  
Spectroscopic Methods ◽  
X Ray ◽  
Partial Formation

The equilibria and mechanism of addition of protons to the ethylenediphosphinetetraacetate anion (L4-) were studied in solution by the UV, IR, 1H and 31P NMR spectroscopic methods. A total of six protons can be bonded to the anion. They are added stepwise, first with partial formation of zwitterions containing P-H bonds, which then dissociate with formation of the free acid, H4L, where all four protons are bonded in carboxyl groups. The formation of zwitterions is strongly dependent on the concentration. In the final stage, the acid bonds two additional protons to form the bis-phosphonium cation, H6L2+. A number of isostructural salts containing this cation, H4L.2 HX (X = Cl, Br, I), have been prepared. The X-ray crystal structure determination of the bromide confirmed the expected arrangement. The bromide crystals are monoclinic, a = 578.2, b = 1 425.0, c = 1 046.7 pm, β = 103.07° with a space group of P21/c, Z = 2. The final R factor was 0.059 based on 1 109 observed reflections. The structure consists of H6L2+ cations containing protons bonded to phosphorus atoms (P-H distance 134 pm) and of bromide anions, located in gaps which are also sufficiently large for I- anions in the isostructural iodide. The interbonding of phosphonium cations proceeds through hydrogen bonds, C-OH...O=C, in which the O...O distance is 275.3 pm.

scholarly journals Radical Ion Salts and Complexes, Part XVII. TCNQ Salts of 1,4-Dimethylpyridine and 2,3-Bis(1-methyl-4-pyridinio)butane

1999 ◽  
Vol 23 (3) ◽  
pp. 196-197
Author(s):  
Timothy J. Houghton ◽  
Stephen C. Wallwork
Keyword(s):  
Structure Determination ◽  
X Ray ◽  
Electrical Conductivities ◽  
Complex Salts ◽  
Radical Ion Salts

X-Ray structure determination of the complex salts [MeNC5H4Me]+[TCNQ2]- [1,4-dimethylpyridinium 2(7,7,8,8-tetracyanoquinodimethane) (1-); I] and [Me(NC5H4)(Me)CH-CH(Me)(C5H4N)Me]2+[TCNQ4]2- [ meso-2,3-bis( N-methyl-4-pyridyl)butane(2+) 4(7,7,8,8-tetracyanoquinodimethane) (2-); II], where TCNQ=(CN)2C(C6H4)C(CN)2, shows that, although in both salts the TCNQ moieties are stacked in columns, lateral shifts break these columns into diads for I and tetrads for II causing their electrical conductivities to be only moderate (Σ = 2–4 × 10−3 ohm−1 cm−1).

Syntheses, X-ray, MSn, NMR and CD structure determination of nickel(II) complexes of Schiff bases of (S)-N-(2-benzoylphenyl)-1-benzylpyrrolidine-2-carboxamide and aromatic α-amino acids

Polyhedron ◽  
2008 ◽  
Vol 27 (17) ◽  
pp. 3477-3483 ◽  
Author(s):  
Milan Nádvorník ◽  
Vratislav Langer ◽  
Robert Jirásko ◽  
Michal Holčapek ◽  
Tomáš Weidlich ◽  
...  
Keyword(s):  
Amino Acids ◽  
Schiff Bases ◽  
Structure Determination ◽  
X Ray ◽  
Determination Of Nickel

Theoretical Study and X-ray Structure Determination of Dimethyldihydropyrene

1998 ◽  
Vol 63 (9) ◽  
pp. 3125-3127 ◽  
Author(s):  
Richard Vaughan Williams ◽  
W. Daniel Edwards ◽  
Ashwani Vij ◽  
Robert W. Tolbert ◽  
Reginald H. Mitchell
Keyword(s):  
Structure Determination ◽  
Theoretical Study ◽  
X Ray

scholarly journals X-ray crystallographic structure determination of the smoke-derived karrikin KAR3

2013 ◽  
Vol 88 ◽  
pp. 107-109 ◽  
Author(s):  
J.J. Nair ◽  
O.Q. Munro ◽  
M. Pošta ◽  
H.B. Papenfus ◽  
P. Beier ◽  
...  
Keyword(s):  
Structure Determination ◽  
Crystallographic Structure ◽  
X Ray

Structure determination of ultrathin NbSe2 films by Grazing incidence x-ray diffraction

1994 ◽  
Vol 89 (7) ◽  
pp. 583-586 ◽  
Author(s):  
Toshihiro Shimada ◽  
Yukito Furukawa ◽  
Etsuo Arakawa ◽  
Kunikazu Takeshita ◽  
Tadashi Matsushita ◽  
...  
Keyword(s):  
Structure Determination ◽  
Grazing Incidence ◽  
X Ray Diffraction ◽  
X Ray
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