Chelation of Na+ cations in nonaqueous solvents. Structural requirements and methodological considerations

Intrinsic formation constants for complexes of Na⁺ ions with a series of polyamines have been determined from²³Na NMR measurements in binary mixtures of tetrahydrofuran (THF) and amines. The results show in a totally unambiguous manner a regular decrease in the magnitude of the chelate effect with the number of atoms intervening between the nitrogen ligators. The key assumption, tetracoordination of the cation, is critically examined, and experimental evidence is adduced in its support.     

Détermination du champ de force de valence de l'ion : Son apport dans l'étude de la conformation

A valence force field for α-glycine is proposed and normal modes of vibration are discussed. The study of the small isotopic shifts of ¹⁵N and ¹⁸O is shown to be fundamental in the determination of the force field. There is a quantitative relationship between the isotopic shifts observed on low frequency absorptions and molecular conformation. The perturbations of the ion force field from one crystalline form to another and from solid state to aqueous solution are also discussed.     

Smooth massless limit of field theories. II

It is shown that the massless limit of any Fierz-Pauli field theory, in the external source approximation, is smooth under certain conditions on the sources. These conditions are no stronger than those that arise from the internal consistency of the massless field theory.     

Quasi-classical treatment of multinucleon transfer reactions

The surface nature of the transfer reaction and the quasi-classical relative motion of the nuclei imply strong conditions on optimal scattering angles andQ-values. These are evaluated using the method of stationary phases. Recoil effects are considered. The agreement with experiment is good.     

Spectrophotometric determination of tartaric acid with beta-naphthol

Tartaric acid (50-800 mug) is reacted with beta-naphthol (5 mg) in 90 % sulphuric acid (2 ml) for 30 min on a steam-bath. The solution is cooled and diluted to 25 ml with 90% sulphuric acid and the absorbance is measured at 603 nm. Several absorption maxima are observed and the ratio and intensity of these depend on the concentration of acid during and after the reaction, and on the beta-naphthol concentration. All tartaric acid isomers give essentially the same colour and absorbance. Interference studies are reported.