Darstellung und Eigenschaften von Norbornylquecksilberverbindungen

Preparation and Properties of Norbornyl Mercury Compounds Bis(1-norbornyl) and bis(2-norbornyl)mercury, 1- und 2-norbornylmercury chloride and 1-norbornylmercury i-butyl were synthesized and characterized by ¹³C-N.M.R. investigations and in case of bis(1-norbornyl) mercury also by the I.R. and mass spectrum. The ¹J(¹⁹⁹Hg? ¹³C) coupling constants of the 1-norbornyl compounds demonstrate the trans-influence of the norbornyl anion.     

A review of time-domain impedance modelling and applications

Time-domain impedance boundary conditions are reviewed and similarities between the models are shown. The extended Helmholtz resonator model is used with a time-domain impedance boundary condition for impedance eduction and simulation of the noise radiation from a lined aeroengine nozzle. Model parameters obtained by impedance eduction from flow duct measurements and then used to predict the noise radiation for realistic aeroengine nozzle flow and geometry. The prediction of sound radiation from a coaxial jet nozzle at approach conditions with the educed model parameters is performed in 2D and 3D. Various features of the numerical method that enable it to be used for realistic applications are presented. This includes the suppression of flow instabilities in the linear inviscid solution and analysis of the solution to prove the global conservation of acoustic energy in each individual result. It is found that the current approach is too time consuming for optimisation, even for a 2D simulation using parallel processing. Thus, finally the potential of porting a CAA method to the graphics processing unit (GPU) is shown in one example. The GPU based computation is about 100 times faster. The results are encouraging, even though the GPU variant needs further validation.     

Vinylierung und 91Zr-NMR-Spektren von Substituierten Zirconocendichloriden

Vinylation and ⁹¹Zr N.M.R. Spectra of substituted Zirconocene Dichlorides Substituted zirconocene dichlorides react with vinyl lithium with formation of zirconacyclopent-2-enes, Cp₂ZrCH = CHCH₂CH₂, or zirconocene butadiene complexes, Cp₂Zr(C₄H₆). The compounds obtained were characterized by their ¹H and ¹³C n.m.r. spectra. The ⁹¹Zr n.m.r. chemical shifts of substituted zirconocene dichlorides correlate with the bond angles Cp′? Zr? Cp′ and Cl? Zr? Cl respectively. They can be used to estimate the reaction behaviour of zirconocene dichlorides.     

Beiträge zur Chemie der Alkylverbindungen von Übergangsmetallen. XXI [1] Versuche zur Alkylierung von Vanadin(IV)-chlorid und Vanadinoxidtrichlorid

Inhaltsübersicht. Es wird über Reaktionen von Vanadin(IV)-chlorid mit Zinkdialkylen und Bortrialkylen berichtet. Dabei entstehen aus Vanadin(IV)-chlorid und Zinkdialkylen Komplexe des Vanadin(III)-chlorids, Vanadin(II)-chlorids und von Alkylvanadindichloriden mit Zinkchlorid, Alkylzinkchloriden oder Zinkdialkylen. Bortrialkyle bewirken die Bildung von reaktivem Vanadin(III)-chlorid, das in Komplexe mit Diäthyläther der Formel VCl₃ · n O(C₂H₅)₂ (n = 1–3) übergeführt werden konnte. Contributions to the Chemistry of Transition Metal Alkyl Compounds. XXI. Experiments for the Alkylation of Vanadium Tetrachloride and Vanadium Oxidetrichloride Abstract. It is reported on experiments for alkylating vanadium tetrachloride by means of zinc dialkyls and boron trialkyls. Zinc dialkyls causes the formation of complexes of vanadium tetrachloride, vanadium trichloride and alkyl vanadium dichlorides with zinc chloride, alkyl zinc chlorides and zinc dialkyls. In the reactions with boron trialkyls high reactive vanadium trichloride is formed, which reacts with diethyl ether to complexes with the formula VCl₃ · n O(C₂H₅)₂ (n = 1–3).     

Beiträge zur Chemie der Alkylverbindungen von Übergangsmetallen. XIII. Über die Reaktion von Vanadinsäure-triisopropylester mit Zinkdimethyl—Zur Kenntnis des Methylvanadinoxiddiisopropoxids

Contributions to the Chemistry of Transition Metal Alkyl Compounds. XIII. the Reaction of Vanadium Isopropyl Ester with Dimethyl Zinc. — On the Formation of CH₃VO(i-OC₃H₇)₂ Dimethyl zinc reacts with ortho vanadium acid triisopropyl ester forming methyl zinc isopropoxide (CH₃Zn-i-OC₃H₇)_n and methyl vanadium oxide diisopropoxide CH₃VO(i-OC₃H₇)₂. The new σ-organovanadium compound was isolated and thoroughly characterized.     

The use of a lyotropic liquid-crystalline medium and residual dipolar coupling constants for determination of the spatial structure of thiacalix[4]arenes in solutions

The possibility of using an approach for the elucidation of the spatial structure of functionalized thiacalix[4]arenes based on the determination the residual dipolar coupling constants between the ¹H and ¹³C nuclei separated by one chemical bond (¹ D _CH) in lyotropic liquid-crystalline media (poly--benzyl-L-glutamate and CDCl₃) is demonstrated for the first time. This approach was used to distinguish between the cone and 1,3-alternate conformations of 5,11,17,23-tetra-tert-butyl-25,26,27,28-tetrakis(2-oxopropyloxy)-2,8,14,20-tetrathiacalix[4]arene. The results were confirmed by the data from 2D NMR (¹H—¹H) NOESY experiments for these compounds in an isotropic solvent (CDCl₃).     

Chirale Dimethylgalliumaminoalkoxide

Chiral Dimethylgallium Amino Alkoxides Me₃Ga reacts with (S)-1-methyl-2-pyrrolidinyl-methanol, (+);(–)-2-piperidyl-methanol, and (S)-α,α,-diphenyl-2-pyrrolidinyl-methanol in molar ratio 1 : 1 with formation of the corresponding dimethylgallium aminoalkoxides 1 – 3 . As a consequence of the Ga–N-interaction new centres of chirality containing asymmetric surrounded N-atoms are formed. Compounds 1 – 3 were characterized by their ¹H, ¹³C nmr and mass spectra. The crystal structures of 1 – 3 were determined by single crystal structure analysis. 1 and 2 are dimeric in solid state, 3 is forming monomeric molecules. 1 and 3 crystallize in the monoclinic space group P2₁ with Z = 2, a = 7.245(4), b = 11.887(3), c = 11.807(6) Å, β = 93.48(3)° for 1 and Z = 4, a = 11.0871(7); b = 6.539(4), c = 12.6919(8) Å, β = 107.04(1)° for 3 . 2 and 2 a crystallize in the monoclinic space groups C2/m and C2/c with Z = 2, a = 15.891(3), b = 9.526(2), c = 7.345(1) Å, β = 111.89(3)° for 2 and Z = 4, a = 19.374(4), b = 8.430(2), c = 19.961(4) Å, β = 100.09(3)° for 2 a .     

Darstellung,Eigenschaften und Molekülstrukturen von chiralen Dimethylaluminium-aminoalkoxiden

Preparation, Properties, and Molecular Structures of Chiral Dimethylaluminum Amino Alkoxides Dimethylaluminium-2-piperidylmethoxide ( 1 ), N-methyl-3-piperidyloxide ( 2 ), R(–)-2-aminobutoxide ( 3 ) and cis-1 R, 2 S-2-N-benzylaminocyclohexyl-1-methoxide ( 4 ) were obtained by reaction of Me₃Al with the corresponding aminoalkohols in n-pentane. The compounds were characterized by ¹H, ¹³C, and ²⁷Al n.m.r. spectroscopy. The molecular structures of 1 , 3 , and 4 were determined by X-ray diffraction. The compounds form oxygen-bridged dimers and in consequence of an Al–N interaction two additional chelate rings. The bond distances of the central Al₂O₂ ring correspond with 1.9 Å to those of known dialkylaluminumalkoxides. The Al–N bond distances run to 2.18 Å which indicates a strong EDA interaction.