Darstellung und Kristallstruktur von Cadmiumazid Cd(N3)2

Preparation and Crystal Structure of Cadmium Azide Cd(N₃)₂ Solvent free, binary cadmium azide was synthesized by the reaction of cadmium carbonate and a 24 weight% solution of HN₃ in water. Cadmium azide is a colorless, crystalline powder which is highly sensitive to percussion and heat. Caution, the manipulation of Cd(N₃)₂ is very dangerous! The crystal structure was solved by single‐crystal methods and the phase purity was verified by a Rietveld refinement (Cd(N₃)₂, Pbca, no. 61; a = 7.820(2), b = 6.440(2), c = 16.073(3) Å; Z = 8, 1174 independent reflections, 64 parameters, R1 = 0.022). Cadmium azide crystallizes in a new structure type. In the crystal there are edge‐sharing Cd₂(N₃)₁₀ double octahedrons which are further connected to other units by azide bridges. Vibrational spectroscopic investigations (Raman an IR) are discussed with respect to the crystal structure data.     

Asymmetric diels-alder reactions : facile preparation and structure of sulfonamido-isobornyl acrylates

The crystalline chiral auxiliaries $\text{2}$,$\text{3}$ and $\text{4}$ were prepared from camphor-10-sulfonyl chlorides in 2 steps. Their readily accessible acrylates underwent efficient asymmetric diels-alder additions to cyclopentadiene, the topicity of which agrees with X-ray evidence.     

The crystal structures of two Mercury Perrhenates

The mercury perrhenates with the empirical formulas HgReO₄ and Hg₂ReO₅ were prepared by annealing powdered mixtures of mercury(II)oxide and mercury(II)metaperrhenate Hg(ReO₄)₂ in sealed silica tubes. Their crystal structures were determined from single-crystal X-ray data. HgReO₄ crystallizes dimeric with nearly linear O₃Re? O? Hg? Hg? O? ReO₃ molecular units and Hg₂ReO₅ has a solid state structure, where Hg(I) and Hg(II) together with oxygen atoms form 14-membered rings, which are condensed to two-dimensionally infinite polycationic nets of composition (Hg₂²⁺ · 2 HgO)_n. These nets are separated from each other by tetrahedral ReO₄^? anions.     

Applications of adsorptive stripping voltammetry for the trace analysis of metals, pharmaceuticals and biomolecules

 A review with 159 references is presented on the applications of adsorptive stripping voltammetry (AdSV) for determining trace metal ions in different environmental samples (e.g. water, soil, plant, biological fluids). The analytical applications of AdSV to biologically active organic compounds (e.g. pharmaceuticals, pesticides, biomolecules) are also discussed. Received: 18 December 1995/Revised: 8 January 1997/Accepted: 12 January 1997     

The electronic structure of molecules by a many-body approach

The vertical valence ionization potentials of cyclopropane, ethylene oxide and ethylene imine are calculated by a many-body Green's function method. For C₃H₆ the ordering of the ionization potentials is 2e(), 1e(), 2a₁(), 1a₂(), 1e(). The assignment of the 2a₁ and the 1a₂ ionization potentials which has been controversial is thus clarified. The ordering is in agreement with the result obtained via Koopmans' theorem. For ethylene oxide and ethylene imine Koopmans' theorem fails in predicting the correct order of ionic states. For C₂H₄O the ordering of the ionization potentials is 2b ₁(), 4a ₁, 1a ₂(), 2b ₂,3a ₁, 1b ₁(), 1b ₂, 2a ₁ and for C₂H₅N 6a, 5a, 3a, 2a, 4a, 3a, 1a, 2a. The agreement of the computed ionization potentials with the experimental values is very satisfactory.     

Conformationally Controlled Odor Perception in ‘Steroid-type’ Scent Molecules

A series of compounds possessing a ‘Steroid-type’ scent and related to 4-(4′-t-butylcyclohexyl)-4-methyl-2-pentanones ( 1 and 2 ) has been synthesized. The odor of these compounds has been found to be dependent on their conformation; only when the molecule can assume a steroid-like shape there is an interaction with the odor chemoreceptor.     

Piperaceae alkaloids: Part IV. Structure and Synthesis of Cyclostachine A,Cyclostachine B and Cyclopiperstachine

Three new alkaloids designated as cyclostachine A (2), cyclostachine B (7) and cyclopiperstachine (10) have been isolated from Piper trichostachyon C. DC. Their structures have been derived on the basis of spectral and degradative studies and confirmed by synthesis. The ¹H- and ¹³C-NMR. spectra of these compounds are discussed.