Regiochemistry of addition of aminoheterocycles to α-cyanocinnamonitriles: formation of aza-bridged bi- and tricycles

The additions of various five-membered ring aminoheterocycles to α-cyanocinnamonitriles were studied. Regiochemistry of product formation can in most cases be controlled by choosing the appropriate electrophile. An α-cyanocinnamonitrile with an additional β-leaving group normally provides products arising from initial attack of the ring amino group, while exo attack predominates in the case of the parent α-cyanocinnamonitrile. Aminopyrazole and aminoindazole provide only exo products with either electrophile. Product assignments were made via X-ray and 2D NMR methods; these assignments serve as a benchmark to several literature references and to future investigations of conjugate additions of these nucleophiles.     

Intermolecular potentials obtained from high-energy alkali scattering

Intermolecular potentials have been obtained from high-energy total cross sections for several alkali metal systems: CS + He, Ne, Ar, CH₃NO₂; K + CH₄, C(CH₃)₄, C₆H₆, c-C₆H₁₂, CH₃I, CCl₄, SF₆, N₂. For the CS-rare gas cases and K + N₂ only the repulsive part was determined. For the rest both attractive and repulsive parts were seen.     

On the molecular structure and nmr spectrum of cis-[PtPh2(Ph2PCH2PPh2)]

The X-ray crystal structure analysis of cis-[PtPh₂(Ph₂PCH₂PPh₂)] suggests that the unusually low PtP coupling constant is a consequence of distortion of the valency angles at the platinum and phosphorus atoms; the restrictive geometry of the chelate ring does not effect the lengths of the metal—ligand bonds.     

Industrial exposure to arsenic

The normal levels of arsenic in human tissue are reported together with the arsenic concentrations found in the investigation of a large number of industrial exposure incidents. These results are useful for establishing that industrial exposure has taken place and for confirming arsenic poisoning but they cannot be used realistically to predict that any person or group will suffer a visible deterioration in health because no correlation between arsenic contamination and symptoms can be made. Industrial workers who are affected by arsenic exposure are often no more exposed than their co-workers.     

The relationship between transmission efficiencies in the FRR and fat modes of an electron spectrometer

The electron transmission efficiency as a function of kinetic energy for an electron spectrometer operating in the fixed analyser transmission (FAT) mode has been determined by direct comparison with the known transmission efficiency in the fixed retard ratio (FRR) mode. Results obtained from the background intensity and from the relative peak heights of a number of elements compare well with each other. They suggest that transmission in the FAT mode is nearly independent of kinetic energy.