Microwave spectra of deuterated ethanes: Internal rotation potential function and rz structure

The microwave spectra of CH₃CHD₂ in the first excited torsional state and of CH₃CH₂D and CD₃CH₂D in the ground states have been observed by a source-modulation spectrometer and analyzed to determine the two potential constants, V₃ and V₆, simultaneously and also to assess the isotopic effects on the potential function. The results obtained for C₂H₆ are V₃ = 2.882 ± 0.010 and V₆ = 0.020 ± 0.010 kcal/mole. The staggered conformation in ethane was established by observing microwave spectra of gauche CH₂DCH₂D. The r_z structure of ethane was recalculated by adding precise rotational constants obtained in this work to previous microwave and infrared data.     

Polarized (letter ‘8’) memory in CdSe point contact diodes

Polarized memory, i.e., the memory in which switching between ON and OFF states depends on the polarity of bias voltage has been found in point contact diodes on single crystals of CdSe, CdS, CdTe, GaAs and GaP. The detailed features of switching characteristics depend on the choice of metals for the point contact electrode, on the sharpness of the contact and also on the resistance of the current limiter in the circuit. Observation of the transients between ON and OFF has also been performed.     

The isolation and structures of euphoscopins a and b

Two new toxic substances, euphoscopins A and B, have been isolated from the plant $\text{Euphorbia}$$\text{helioscopia}$ L., and their absolute stereostructures also been elucidated on the basis of their spectral data coupled with an X-ray crystallographic analysis of the $\text{p}$-bromobenzoate readily obtained on treatment of euphoscopin A with $\text{p}$-bromobenzoyl chloride - pyridine. These antitumor substances belong to a group of jatrophone-type diterpenes.     

Artin-Gruppen und Coxeter-Gruppen

Ohne Zusammenfassung     

Pentadienylsilanes as new reagents of the siteselective dienylmethylation of electrophiles promoted by a Lewis acid

(2,4-Pentadienyl)- and (2,4-hexadienyl)trimethylsilanes, prepared from the corresponding pentadienylpotassiums and trimethylchlorosilane, react smoothly with various electrophiles such as acetals, aldehydes and acid halides to give pentadienylation products, with regiospecific transposition of the pentadienyl group.