Phosphoranes bicycliques a liaison PH : Bases de Lewis potentielles

By reaction of Borane Dimethyl Sulfide on the bicyclophosphorane $\text{1}$ the adduct $\text{2}$ is obtained with 56 % yield; by-products $\text{3}$ and $\text{4}$ are characterized .     

Anionic polymerization of 2-vinylpyridine initiated by symmetrical organomagnesium compounds in tetrahydrofuran

Anionic polymerization of 2-vinylpyridine has been studied, initiated either by dialkyl and diaryl magnesium or by living oligomers in tetrahydrofuran solution at 20°C. Spectrophotometric observations indicate the existence of stable active species with different structures. Kinetic data for propagation and viscosimetric measurements on two-ended polymers agree with a cyclic structure of living polymers and lead us to the conclusion of the existence of reactive negative “tripleions.”     

Isomerisation de l'ion moleculaire de derives substitues polycycliques du benzodioxinne-1,4

Three fragmentations (loss of phenyl, hydrogen and a RCO radical) of benzocyclobutene derivatives of differently substituted 1,4-benzodioxin were studied. In some cases these molecules, deuteriated in a specific position, revealed the existence of several isomers of the molecular ion.     

Un correlateur optique par filtrage chromatique fonctionnant en temps reel et en source etendue de lumiere blanche

Relief-type holograms were copied on PVC sheets from a master made on a photosensitive As-Se-Ge amorphous film. One hundred hologram copies could be printed successively without degradation of the reconstructed image quality. Typical diffraction efficiency of the copied hologram was about 2%.     

Recherches théoriques sur la structure électronique de molécules contenant des atomes hybridés en sp:

Résumé La méthode L. C. A. O. améliorée est utilisée pour étudier la structure électronique des molécules de vinylacétylène, de divinylacétylène et de butatriène, réduites à leur système . Les énergies des premières transitions N V sont en excellent accord avec l'expérience. Une relation entre l'indice de liaison mobile et la distance interatomique, pour des liaisons reliant des atomes hybridés l'un en sp et l'autre en sp ₂, est proposée.

---

The improved LCAO theory is used to study the electronic structure of vinylacetylene, divinylacetylene and butatriene molecules, reduced at their system. The first N V transition energies are in excellent agreement with experiment. A relation between mobile bond order and bond distance, for bonds between sp and sp ₂ hybridized atoms, is proposed.

---

Zusammenfassung Die elektronische Struktur der auf ihr -System reduzierten Moleküle Vinylacetylen, Divinylacetylen und Butatrien wird mit Hilfe der verbesserten LCAO-Methode untersucht. Die berechneten Energien der ersten N V-übergÄnge stimmen mit dem Experiment ausgezeichnet überein. Eine Beziehung zwischen Bindungsabstand und -Bindungsindex für Bindungen zwischen sp- und sp ₂-hybridisierten Atomen wird vorgeschlagen.

     

Evaluation of higher-order effective potentials with dimensional regularization

A new and simple method for evaluating high-order effective potentials is presented. It is based on the renormalization procedure of 't Hooft and Veltman used in conjunction with the scheme of dimensional regularization. Explicit calculations of the effective potential of a scalar field in two-loop approximation are carried out.     

Une méthode topologique pour L'etude de la propriété de ramsey

The paper is devoted to the study of some particular subclasses of the class of Ramsey sets, each one associated with an ultrafilter onΝ. By topological methods, we show that every such class contains the analytic sets. This generalizes the results of Silver and Mathias on this subject. Furthermore some applications to functional analysis are given, and a discussion of the additivity of these classes and of the Ramsey property of the ultrafilters is presented, under the hypothesis of Martin's Axiom.      

Synthese et etude par resonance magnetique nucleaire du carbone 13 et de l'etain 119 d'une serie de triorganostannyl-2 butanes

Optically active triorgano-2-stannylbutanes have been synthetized by different methods, one being the direct substitution of optically active s-butyl halides with triorganostannyl alkali metals. This route involves a complete or partial inversion of configuration at the chiral carbon atom. Carbon-13 and tin-119 NMR data are reported as support for the identification of eight triorgano-2-stannylbutanes. The special case of tetra(2-butyl)tin, with four identical chiral centres has been examined.     

Étude par rm13c d'alcaloïdes à squelette acridinone 9(10h) et pyrido(4,3b) carbazole(6h)

Both synthetic and natural acridinone and pyridocarbazole alkaloids have been studied by ¹³C NMR and simple model systems used for comparison.