Dérivés Alléniques du Phosphore. Influence de l'État de Coordination du Phosphore et de la Nature des Radicaux Liés au Phosphore sur les Signes de J(P?H)

The signs of the phosphorus-proton coupling constants in various allenic organophosphorus compounds have been determined by either analysis of the AB₂X spectra or double resonance. Probable absolute signs have been obtained by taking ³J(P? H) as positive. In allenic phosphine oxides, the following signs are obtained: ²J(P? H) +ve, ³J(P? H) +ve, ⁴J(P? H) ?ve, ⁵J(P? H) +ve and the ⁴J(P? H) coupling constant varies mostly with the inductive effect of the substituents bound to the phosphorus atom. In allenic phosphines, these sings are: ²J(P? H) +ve, ³J(P? H) +ve, ⁴J(P? H) ?ve and +ve and the ⁴J(P? H) coupling constant varies with both the inductive and resonance effects to the substituents. This coupling constant is negative except when the phosphorus atom is bound to groups which are electron-donating by resonance effects. These results are discussed in relation to the pπ? dπ bonding in phosphine.     

Étude théorique de l'oxime de l'acroléine

Résumé La méthode semi-empirique de Pariser-Parr-Pople est appliquée à l'étude des quatre isomères géométriques de l'oxime de l'acroléine, en utilisant les paramètres empiriques déterminés précédemment pour les oximes de la p-benzoquinone. L'analyse théorique des énergies totales permet de penser sans ambiguité que seule la forme -trans peut exister. Dans ces conditions, le spectre électronique calculé est en très bon accord avec les résultats expérimentaux.

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The Pariser-Parr-Pople's method is applied to the study of the four -geometric conforme of the oxime derived from acrolein, using empirical parameters precedently defined for the study of p- benzoquinone oximes. The theoretical analysis of total energies allow the conclusion that alone the -trans form may exist. In these conditions, the computed electronic spectrum is in good agreement with experimental data.

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Zusammenfassung Mit der PPP-Methode wurden die vier geometrischen Isomeren des Oxims des Acrolein behandelt. Dabei wurden die empirischen Parameter benutzt, die schon bei der Untersuchung des Oxims des p-Benzochinons verwandt wurden. Es ergibt sich, daß nur die -trans Form existiert und für diesen Fall auch das berechnete Elektronenspektrum mit den experimentellen Werten gut übereinstimmt.

     

Reactivity of 4-halogeno 1-vinyl naphthalenes in cationic polymerization

Improved methods for the synthesis of 4-halogeno 1-vinylnaphthalenes are proposed. Reactivity ratios are determined for the following systems: 4-fluoro-1-vinyl naphthalene-styrene, 4-chloro-1-vinyl naphthalene-styrene, and 4-bromo-1-vinyl naphthalene-styrene. The determinations are performed at various specific temperatures and the relative activation parameters are obtained. It appears that the reactivity of 1-vinyl naphthalene is drastically decreased when substituted by a halogen. In the case of 1-vinyl naphthalene the selection is enthalpically controlled.     

Etude comparative des proprietes magnetiques des oxydes lamellaires ACrO2 (A = Li,Na, K)—I: Etude par effet Mössbauer de LiCrO2 dope par le fer

A Mössbauer study of the dimensionality of magnetic interactions in the layer oxide LiCr_0.99Fe_0.01O₂ shows a 2-D behaviour.     

The electronic structure of sulphur chloride penta-fluoride

The electronic structure of SCIF₅ is computed within the framework of the CNDO/2 approximation on the basis of Kewley's microwave geometrical data and is compared with our previous results on SF₆. The charge distribution and the value of the dipole moment are discussed as a function of the F-S-F_ax angle and an inversion of the net charge on Cl is observed when passing through the 95° value for (F-S-F_ax) angle.     

Sels d'aziridinium stables c-fonctionnalisés II: Stéréochimie de la quaternisation,synthèses stérèodirigées de composés n-trideutériométhylés et attribution de leurs configurations relatives par el'fet overhauser nucléaire

Aziridines bearing a functionality on a ring carbon and an alkyl or deuteriomethyal group on nitrogen have been quaternized at different temperatures. The configurations of the resulting, stable, diastereomeric aziridinium ions have been assigned by Nuclear Overhauser effect. The stereoselectivity in quaternization is discussed.