Zur reaktionsweise von triafulvenen mit azomethinyliden

The reaction of the azomethine ylides 2a–c with cyclopropenones 3 and of 2a with methylene cyclopropenes 7 leads via (3+3)-cycloaddition to pyridones-4 5 and 1,4 - dihydro - N - methyl - 4 - methylene - pyridines 8, respectively. The merocyanine systems 8 exhibit marked solvatochromic and thermochromic properties.     

Zur photochemie der triafulvene—III: Photochemische umwandlungen des 2-(diphenylcyclopropenyliden)-indan-1.3-dions

The photochemical transformations of triafulvene 6 in solvents of different type are investigated. Irradiation of 6 in methanol/ethanol leads to products which are derived from quinodimethane 7 by addition of alcohol in 1.2 or 1.6 fashion. When 6 is irradiated in acetonitrile/benzonitrile, products of complex structural type $\text{17}\text{19}$ are obtained. For structure elucidation a X-ray crystallographic analysis is performed for 17a.     

Die Reaktion von Trithiazylchlorid mit Titantetrachlorid Die Kristallstruktur von (S4N5)2[Ti2Cl10]

Reaction of Trithiazyl Chloride with Titanium Tetrachloride. Crystal Structure of (S₄N₅)₂[Ti₂Cl₁₀] In the reaction of trithiazyl chloride with titanium tetrachloride, chlorine is abstracted and the brown-yellow adduct TiCl₄(N₂S₂) is obtained. In this compound — according to its i.r. spectrum — a N₂S₂ ring is bonded to the titanium via the N atoms, thus forming a polymer. As a by-product, brown crystalline (S₄N₅)₂[Ti₂Cl₁₀] forms. Its crystal structure was determined and refined with X-ray diffraction data (R = 0.042 for 812 reflexions). It crystallizes in the monoclinic space group P2₁/c with two formula units per unit cell. The lattice constants are a = 670, b = 1 633, c = 1108 pm, β = 97.24°. The structure consists of S₄N₅^⊕ cations, which are nearly equal to those in [S₄N₅]Cl, and [Ti₂Cl₁₀]^2? anions, which are nearly identical with those in (PCl₄)₂[Ti₂Cl₁₀].     

Bryophytes,a Source of Biologically Active,Naturally Occurring Material?

Chemical studies of the plant category of mosses (bryophytes) were neglected for a long time. They have now been shown to be a storehouse of naturally occurring materials, including some with novel chemical structures. Many of these materials display considerable biological activity. Investigations are hampered frequently by too small amounts of plant material. The resulting low yields of components are then generally inadequate to permit testing for biological activity. In vitro culture and appropriate chemical synthesis on a preparative scale are being undertaken to overcome this difficulty.     

The Sudakov form factor beyond the leading logarithmic approximation

We present the general form of the asymptotic behavior of the massless electron-photon vetex function in quantum electrodynamics in the limit whereq ², the virtual mass of the photon, becomes large. All the logarithms inq ² are taken into account, whereas inverse powers ofq ² are neglected. In contradistinction to previous investigations we consider the off-shell vertex function and work in the Feynman gauge. Extensive use is made of the α-representation of Feynman integrals.     

Das Quadrupolmoment des 8,42 keV-Niveaus von Tm169

The hyperfine interaction of the 8·42 kev level of Tm¹⁶⁹ was investigated using the Mössbauereffect in Tm-ethylsulfate. The hyperfine-splitting is of pure quadrupoletype; its temperature dependance between 6°K and 250°K was measured. The spectroscopic quadrupolemoment of the 8·42 kev level was determined asQ=?(1·1±0·1) barn, leading to an intrinsic quadrupolmoment ofQ ₀=+(5·5±0·5) barn.