Stephan Scheins

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The electron densities of five morphine related molecules (codeine, diprenorphine, naltrexone in the neutral and protonated states, and dextromethorphan) were determined from high-resolution X-ray diffraction experiments (Mo Kalpha and synchrotron primary radiation) at low temperature and CCD area detection techniques. Bond topological analyses were(More)
The electron density distribution of morphine hydrate has been determined from high-resolution single-crystal X-ray diffraction measurements at 25 K. A topological analysis was applied and, in order to analyze the submolecular transferability based on an experimental electron density, a partitioning of the molecule into atomic regions was carried out,(More)
A RATIO method for analysis of intensity changes in time-resolved pump-probe Laue diffraction experiments is described. The method eliminates the need for scaling the data with a wavelength curve representing the spectral distribution of the source and removes the effect of possible anisotropic absorption. It does not require relative scaling of series of(More)
A high-resolution X-ray diffraction data set was collected within 48 h at 100 K with synchrotron radiation and area detection. A full topological analysis was applied to the resulting electron-density model. This analysis was followed by a Bader partitioning making use of the zero-flux surfaces of the electron-density gradient vector field. The atomic and(More)
Strychnine has an interesting oligocyclic structure of seven condensed rings. It is easy to crystallize and gives crystals of excellent quality which diffract nicely to high regions in reciprocal space. It was thus chosen for a comparative charge-density study based on four high-resolution data sets (sin theta;/lambda >or= 1.15 A-1) that were measured with(More)
Definitive experimental results on the geometry of fleeting species are at the time of writing still limited to monochromatic data collection, but methods for modifications of the polychromatic Laue data to increase their accuracy and their suitability for pump-probe experiments have been implemented and are reviewed. In the monochromatic experiments(More)
For the measurement of very accurate high-resolution X-ray data for charge-density work, synchrotron beamlines provide a bright radiation source of outstanding properties. Most important are the very high primary intensity and the possibility of choosing hard radiation with lambda approximately 0.5 A or even shorter. This together with area detection and a(More)
The experimental charge densities of the halogenated C(60) fullerenes C(60)F(18) and C(60)Cl(30) were determined from high-resolution X-ray data sets measured with conventional Mo(Kalpha) radiation at 20 K for C(60)Cl(30) and with synchrotron radiation at 92 K for the fluorine compound. Bond topological and atomic properties were analyzed by using Bader's(More)
Mixed-valence trinuclear carboxylates, [M(3)O(O(2)CR)(6)L(3)] (M = metal, L = terminal ligand), have small differences in potential energy between the configurations M(II)M(III)M(III)⇔M(III)M(II)M(III)⇔M(III)M(III)M(II), which means that small external changes can have large structural effects, owing to the differences in coordination geometry between M(2+)(More)