Aqueous telluridoindate chemistry: water-soluble salts of monomeric, dimeric, and trimeric In/Te anions [InTe(4)](5-), [In(2)Te(6)](6-), and [In(3)Te(10)](11-)

Water-soluble salts of monomeric, dimeric, and/or trimeric telluridoindate anions, [K(5)(H(2)O)(2.16)][InTe(4)] (1), [K(5)(H(2)O)(5)][InTe(4)] (2), [K(6)(H(2)O)(6)][In(2)Te(6)] (3), [K(16)(H(2)O)(9.62)][InTe(4)](2)[In(2)Te(6)] (4), [K(133)(H(2)O)(24)][In(3)Te(10)](12)Te(0.5) (5), and [Rb(6)(H(2)O)(6)][In(2)Te(6)] (6), were prepared by a fusion/extraction method starting from the elements and characterized by single-crystal X-ray diffraction as well as spectroscopic methods. The compounds are the first hydrates of telluridoindate salts and thus point toward an aqueous coordination chemistry with binary In/Te ligands. Both crystallization from the extracts as mixtures of salts as well as preliminary spectroscopic investigation of the solutions indicate the presence of an equilibrium of different anionic species. Here, the indates differ from related stannates, which also show pH-dependent aggregation, but to a much lesser extent and in a better distinguishable manner. We present syntheses and crystal structures and discuss observation of the coexistence of different anions both in the solid state and in solution.     

Computations of form and stability of rotating drops with finite elements

^** Email: claus{at}mathematik.uni-freiburg.de We consider the numerical computation of equilibrium shapesof rotating drops and their bifurcations, depending on the angularvelocity. The drops are subject to centrifugal forces and surfacetension alone. We present a path-tracking algorithm which isbased on the discretisation of a continuously formulated Newton'siteration. Our algorithm uses parametric finite elements andavoids artificial symmetry assumptions. The results of our numericalexperiments extend those published by Brown & Scriven (1980,The shape and stability of rotating liquid drops. Proc. R. Soc.Lond. Ser. A, 371, 331– 357) and cover drops of spheroidalas well as annular shape.     

Determination of L-hyoscyamine in atropine and D-hyoscyamine in L-hyoscyamine by chiral capillary electrophoresis as an alternative to polarimetry

A method for the separation of atropine enantiomers, D- and L-hyoscyamine by capillary electrophoresis (CE) has been developed and validated. The advantages of the CE method compared with polarimetry include smaller amounts of analytes and a lower limit of detection of the unwanted enantiomer. Moreover, the present method enables a baseline separation of the analytes and tropic acid, one of the typical impurities of atropine. The developed enantioseparation of atropine was performed using a commercially available sulfated beta-cyclodextrin and was validated for the determination of L-hyoscyamine in atropine as well as for the enantiomeric purity of L-hyoscyamine.     

Die stereoisomeren bicyclo[4.2.0]octan-cis-Diole-(7,8)

The stereochemical assignment of the bicyclo[4.2.0]octane-cis-7,8-diols is reinvestigated. It is shown that the cis-diols prepared by different routes are indeed stereoisomers, the lower melting being the exo-isomer (1), the higher melting the endo-isomer (2). The synthesis of the previously unknown trans-fused bicyclo[4.2.0]octane-cis-7,8-diol (3) via photosensitized cycloaddition of vinylene carbonate to cyclohexene is described.