NMR Spectroscopy of Tetra(propyn- 1-yl)silane in the Solid State and in Solution

2003 ◽  
Vol 58 (8) ◽  
pp. 809-812 ◽  
Author(s):  
Bernd Wrackmeyer ◽  
Oleg L. Tok ◽  
Amin Badshah
Keyword(s):  
Solid State ◽  
Bulk Material ◽  
Point Group ◽  
Coupling Constants ◽  
Data Set ◽  
Tin Compounds ◽  
X Ray ◽  
Nmr Data ◽  
Solid State Structures

The crystal structure of tetra(propyn-1-yl)silane, Si(C≡CMe)4 1, has revealed a completely asymmetric molecule (point group C1). Since this finding concerns a single crystal, the bulk material of 1 was studied by solid-state 29Si and 13C MAS NMR. This confirmed the result of the X-ray analysis, and by comparison with previous NMR measurements of the tin analogue 1(Sn) it is concluded that 1 and 1(Sn) must have very similar solid-state structures which are in contrast to those known for other tetra(alkyn-1-yl)silicon and -tin compounds. The NMR data set of 1 in solution was completed by determination of the magnitude of coupling constants 1J(13C,13C).

Potential Anticancer Agents, XI. X-Ray Structure Determination of Acantholide [1]

1979 ◽  
Vol 34 (9-10) ◽  
pp. 677-682 ◽  
Author(s):  
H. Lotter ◽  
H. Wagner ◽  
A. A. Saleh ◽  
G. A. Cordell ◽  
N. R. Famsworth
Keyword(s):  
Solid State ◽  
Antitumor Activity ◽  
Sesquiterpene Lactone ◽  
Anticancer Agents ◽  
Structure Determination ◽  
Direct Methods ◽  
X Ray ◽  
Activity Evaluation ◽  
Nmr Data

Abstract The X-ray structure of acantholide, a melampolide sesquiterpene lactone from Acanthosper­mum glabratum (D C .) Willd. was determined by the aid of direct methods. The compound was cy­totoxic but displayed no antitumor activity. Evaluation of the X-ray and NMR data indicated that the same conformation exists in the solid state as in solution.

2-Stannylpyridine-Borane Adducts - Multinuclear Magnetic Resonance Study and X-Ray Structure Determination of a 1,4-Dihydro-4 a,1,4-azastannabora-naphthalene Derivative

1995 ◽  
Vol 50 (5) ◽  
pp. 809-815 ◽  
Author(s):  
Bernd Wrackmeyer ◽  
Heidi E. Maisel
Keyword(s):  
Solid State ◽  
Lone Pair ◽  
Molecular Structures ◽  
Coupling Constants ◽  
Hydrogen Atoms ◽  
Naphthalene Derivative ◽  
X Ray ◽  
Cp Mas Nmr ◽  
Solution Changes

Abstract The adduct formation between 2-trimethylstannyl-pyridine (1) and triethylborane, leading to 2a, and 9-borabicyclo[3.3.1]nonane, leading to 2b, was studied by 1H, 11B, 13C, 15N and 119Sn NMR in solution. Changes in the magnitude of the coupling constants J(119Sn, 13C), with respect to the data for I, were analysed. The absolute signs have been determined [all coupling constants nJ(119SnZ3C) to methyl and pyridine carbon atoms in 1 to 3 possess a negative sign and the same is true for nJ(119Sn,1H) of the pyridine hydrogen atoms] by various two-dimensional NMR experiments, and attributed to the influence of the lone pair of electrons at the nitrogen atom in 1. The NMR spectroscopic results for the 1,4-dihydro- 4a,1,4-azastannabora-naphthalene derivative 3, in which structural fragments are present analogous to those in the borane adducts 2, correspond to those for 1 and 2a,b. The molecu­lar structure of 3 has been determined by X-ray analysis [orthorhombic; P212121, a = 713.9(2), b - 1566.0(2), c = 1578.4(2) pm]. Solid-state 13C and 119Sn CP/MAS NMR spectra prove that the molecular structures of 3 in the solid state and in solution are very similar.

scholarly journals Absolute configuration of naturally occurring glabridin

2013 ◽  
Vol 69 (11) ◽  
pp. 1212-1216 ◽  
Author(s):  
Charlotte Simmler ◽  
Frank R. Fronczek ◽  
Guido F. Pauli ◽  
Bernard D. Santarsiero
Keyword(s):  
Absolute Configuration ◽  
X Ray Diffraction ◽  
Data Set ◽  
X Ray ◽  
Naturally Occurring ◽  
Nmr Data ◽  
Stereochemical Analysis ◽  
Medium Pressure Liquid Chromatography ◽  
Species Specific

The title compound {systematic name: 4-[(3R)-8,8-dimethyl-3,4-dihydro-2H-pyrano[2,3-f]chromen-3-yl]benzene-1,3-diol, commonly named glabridin}, C20H20O4, is a species-specific biomarker from the rootsGlycyrrhiza glabraL. (European licorice, Fabaceae). In the present study, this prenylated isoflavan has been purified from an enriched CHCl3fraction of the extract of the root, using three steps of medium-pressure liquid chromatography (MPLC) by employing HW-40F, Sephadex LH-20 and LiChroCN as adsorbents. Pure glabridin was crystallized from an MeOH–H2O mixture (95:5 v/v) to yield colorless crystals containing one molecule per asymmetric unit (Z′ = 1) in the space groupP212121. Although the crystal structure has been reported before, the determination of the absolute configuration remained uncertain. Stereochemical analysis, including circular dichroism, NMR data and an X-ray diffraction data set with Bijvoet differences, confirms that glabridin, purified from its natural source, is found only in a C3Rconfiguration. These results can therefore be used as a reference for the assignment of the configuration and enantiopurity of any isolated or synthetic glabridin sample.

scholarly journals Determination of the relative configuration of tropinone and granatanone aldols by using TBDMS ethers

2012 ◽  
Vol 8 ◽  
pp. 1877-1883 ◽  
Author(s):  
Ryszard Lazny ◽  
Aneta Nodzewska ◽  
Katarzyna Sidorowicz ◽  
Przemyslaw Kalicki
Keyword(s):  
Coupling Constants ◽  
Side Chain ◽  
X Ray Diffraction ◽  
Relative Configuration ◽  
X Ray ◽  
Vicinal Coupling Constants ◽  
Nmr Data ◽  
And Shifts ◽  
Solventless Reaction

The relative configurations oftert-butyldimethylsilyl (TBDMS) ethers of all four diastereomers of the aldols of tropinone (8-methyl-8-azabicyclo[3.2.1]octan-3-one), as well as of granatanone (9-methyl-9-azabicyclo[3.3.1]nonan-3-one), were determined from NMR data, and from the observed interconversion of the diastereomers (exo,antitoendo,synandexo,syntoendo,anti). Theexoforms invert toendoisomers in the presence of silica gel. The relative configuration of a new isomer of tropinone aldol accessible synthetically through the direct solventless reaction of tropinone and benzaldehyde in the presence of water was determined asexo,synby comparison of NMR data of the aldol isomers, in particular vicinal coupling constants and shifts corresponding to the side-chain CH group, with data of related TBDMS derivatives and confirmed by single-crystal X-ray diffraction.

scholarly journals Investigation of Solvatomorphism and Its Photophysical Implications for Archetypal Trinuclear Au3(1-Methylimidazolate)3

Molecules ◽  
2021 ◽  
Vol 26 (15) ◽  
pp. 4404
Author(s):  
Shengyang Guan ◽  
David C. Mayer ◽  
Christian Jandl ◽  
Sebastian J. Weishäupl ◽  
Angela Casini ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Density Functional ◽  
Bulk Material ◽  
Variable Temperature ◽  
Active Phase ◽  
Solvent Free ◽  
X Ray Diffraction ◽  
X Ray ◽  
Aurophilic Interactions

A new solvatomorph of [Au3(1-Methylimidazolate)3] (Au3(MeIm)3)—the simplest congener of imidazolate-based Au(I) cyclic trinuclear complexes (CTCs)—has been identified and structurally characterized. Single-crystal X-ray diffraction revealed a dichloromethane solvate exhibiting remarkably short intermolecular Au⋯Au distances (3.2190(7) Å). This goes along with a dimer formation in the solid state, which is not observed in a previously reported solvent-free crystal structure. Hirshfeld analysis, in combination with density functional theory (DFT) calculations, indicates that the dimerization is generally driven by attractive aurophilic interactions, which are commonly associated with the luminescence properties of CTCs. Since Au3(MeIm)3 has previously been reported to be emissive in the solid-state, we conducted a thorough photophysical study combined with phase analysis by means of powder X-ray diffraction (PXRD), to correctly attribute the photophysically active phase of the bulk material. Interestingly, all investigated powder samples accessed via different preparation methods can be assigned to the pristine solvent-free crystal structure, showing no aurophilic interactions. Finally, the observed strong thermochromism of the solid-state material was investigated by means of variable-temperature PXRD, ruling out a significant phase transition being responsible for the drastic change of the emission properties (hypsochromic shift from 710 nm to 510 nm) when lowering the temperature down to 77 K.

scholarly journals Simple Methylcadmium Alkoxides

2007 ◽  
Vol 62 (10) ◽  
pp. 1339-1342 ◽  
Author(s):  
Surajit Jana ◽  
Tania Pape ◽  
Norbert W. Mitzel
Keyword(s):  
Mass Spectrometry ◽  
Solid State ◽  
Molecular Formula ◽  
Equimolar Ratio ◽  
X Ray ◽  
X Ray Crystallography ◽  
Elemental Analyses ◽  
Solid State Structures ◽  
Structural Aspects ◽  
C Nmr

The reaction of dimethylcadmium with alcohols R-OH in equimolar ratio leads to the formation of tetrameric methylcadmium alkoxides with molecular formula [(MeCd)4 (OR)4] [R = Me (1), Et (2) and iPr (3)]. These compounds have been characterised by 1H, 13C NMR and IR spectroscopy, by mass spectrometry, elemental analyses and by X-ray crystallography (for 2 and 3). The solid state structures show distorted cubane-type aggregates with Cd4O4 cores. The structural aspects and the spectroscopic characterisations of these compounds are discussed.

The solid state structures of the high and low temperature phases of dimethylcadmium

2016 ◽  
Vol 52 (66) ◽  
pp. 10144-10146 ◽  
Author(s):  
Felix Hanke ◽  
Sarah Hindley ◽  
Anthony C. Jones ◽  
Alexander Steiner
Keyword(s):  
Solid State ◽  
Low Temperature ◽  
Dft Calculations ◽  
Methyl Groups ◽  
X Ray ◽  
Solid State Structures

X-ray structures and DFT calculations show that the HT phase is of Me2Cd is two-dimensionally disordered, while the LT phase is ordered. Both phases contain linearly coordinated cadmium atoms; methyl groups are staggered in the HT form and eclipsed in the LT-form.

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