Beiträge zur Chemie der Silicium-Schwefel-Verbindungen. 53. Die Struktur des 1,3-Dimethyl-1,1,3,3-Tetraphenyldisilthians

Contributions to the Chemistry of Silicon-Sulphur Compounds. 53. Structure of 1,3-Dimethyl-1,1,3,3-tetraphenyldisilthiane 1,3-Dimethyl-1,1,3,3-tetraphenyldisilthiane was obtained by an insertion reaction of sulphur with Ph₂ MeSiH. The compound crystallizes triclinically (P1 ; a = 1166.7; b = 1231.1; c = 988.6 pm; α = 113.23; β = 90.34; γ = 112.43°; Z = 2). The X-ray structure analysis shows a bent configuration of the molecule with Si? S? Si = 108.7°. The results are discussed together with the structures of hexaphenyldisilthiane and dimethyltetraphenyldisiloxane.     

Eine infrarotspektrometrische Methode zur Bestimmung von Pyrethrin II aus Pyrethrumextrakten

Ohne Zusammenfassung     

Zucker in Obstpuddingpulver

Ohne Zusammenfassung     

Practical and theoretical aspects concerning the use of salt bridges in electrochemistry

The emf of electrochemical cells containing various sorts of salt bridges between various concentrations has been measured. The net diffusion potential over a salt bridge has been treated theoretically. An expression to calculate the net diffusion potential has been derived and tested on values estimated from the emf measurements. A merit factor has been calculated for a saturated KCl bridge separating two HCl solutions and compared with the merit factor estimated from emf measurements on the cell:Pt|Ag|AgCl, HCl(c₁)|KCl(sat)|HCl(c₂), AgCl|Ag|Pt The practical performance of two commonly used reference electrodes with salt bridges has been tested on emf measurements on KBr solutions.     

Maximally entangled mixed states: creation and concentration

Using correlated photons from parametric down-conversion, we extend the boundaries of experimentally accessible two-qubit Hilbert space. Specifically, we have created and characterized maximally entangled mixed states that lie above the Werner boundary in the linear entropy-tangle plane. In addition, we demonstrate that such states can be efficiently concentrated, simultaneously increasing both the purity and the degree of entanglement. We investigate a previously unsuspected sensitivity imbalance in common state measures, i.e., the tangle, linear entropy, and fidelity.     

Hydrogenolysis of [PhBP3]Fe[triple bond]N-p-tolyl: probing the reactivity of an iron imide with H2

This paper describes the reductive hydrogenolysis of a low-spin (S = 1/2) iron(III) imide. Pseudotetrahedral [PhBP3]FeIIIN-p-tolyl is reduced by hydrogen at ambient temperature and pressure in benzene solution. The reduction appears to proceed in a stepwise fashion. An intermediate S = 2 iron(II) anilide, [PhBP3]Fe(N(H)-p-tolyl), is observed and has been independently generated and structurally characterized. Prolonged hydrogenolysis in benzene results in the complete hydrogenolysis of the Fe-N linkage to release H2N-p-tolyl. The major iron-containing product formed from this step is the diamagnetic cyclohexadienyl complex, [PhBP3]Fe(eta5-cyclohexadienyl), which has also been independently prepared and structurally characterized. Evidence is presented to suggest that the final [PhBP3]Fe(eta5-cyclohexadienyl) product is formed via benzene insertion into a reactive [PhBP3]FeII-H intermediate.     

Pump modulation frequency resolved excited state absorption spectra in Tm<Superscript>3+</Superscript> doped YLF

Excited state absorption (ESA) in a 1% doped Tm:YLF crystal in the range from 1000 nm to 1300 nm is reported. In this spectral range, three ESA bands are expected: ³F₄³F₂ (from 1040 nm to 1096 nm), ³F₄³F₃ (from 1111 nm to 1169 nm), and ³H₄¹G₄ (from 1118 nm to 1240 nm). In a conventional continuous wave ESA setup only the first two bands are observed because the lifetime of the ³F₄ level is much longer (15.6 ms) than the lifetime of the ³H₄ level (1.56 ms). In order to observe the ³H₄¹G₄ ESA band, pump modulation dependent measurements were performed, where the modulation frequency of the pump selects the ESA signal to be measured. PACS 42.62.Fi; 42.70.Hj; 78.20.Ci; 78.20.Bh