A simple model of short-range interactions II. The orientation dependence of the interaction between non-bonded hydrogen atoms

The simple model of short-range interactions described in the preceding paper has been applied to the study of the orientation dependence of the interaction between the non-bonded hydrogen atoms of two CH fragments. Calculation shows that for the same interatomic distance the interaction energy between non-bonded hydrogen atoms is strongly dependent on the relative orientation of the two bonds even for large values ofR.     

Note on the solution of secular problems with two non-orthogonal basis functions

A convenient trigonometric expression for the eigenfunctions and eigenvalues of 2 x 2 secular problems including overlap is presented.     

Low temperature absorption spectra of TcO 4 − and ReO 4 − in KClO4

The low temperature spectra of TcO ₄ ^– and ReO ₄ ^– both show two band systems with pronounced vibrational structures. The bands are identified as¹ A ₁¹ T ₂ transitions. No other bands are observed with certainty. It seems likely that the KClO₄ crystals contain KReO₄ crystallites. They are therefore not pure mixed crystals. It is concluded that the virtual orbital (2e) used in the construction of the low lying states resembles an atomic nd orbital more and more when going from n=3, Mn to n=5, Re.

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Zusammenfassung Die Tieftemperaturspektren von TcO ₄ ^– und ReO ₄ ^– zeigen beide zwei Bandensysteme mit ausgeprägten Schwingungsstrukturen. Die Banden werden als ¹ A ₁¹ T ₂-Übergänge identifiziert. Keine anderen Banden werden mit Sicherheit beobachtet. Es scheint wahrscheinlich, daß die KClO₄-Kristalle KReO₄-Kristallite enthalten und deswegen keine reinen Mischkristalle sind. Es wird geschlossen, daß das virtuelle Orbital (2e), welches zur Konstruktion der tiefliegenden Zustände gebraucht wird, in der Reihe n=3, Mn bis n=5, Re immer weitgehender einem nd-Atomorbital ähnelt.

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Nachwuchsstipendiat, Schweizerischer Nationalfonds.     

Konstitution und physikalische Eigenschaften von Äthern, 7. Mitt.: Unterschiedlich substituierte Glykol- und Pentaerythritäther

Zusammenfassung Für Untersuchungen über das Viskositäts-Temperatur-Verhalten³ und andere physikalische Eigenschaften⁴ werden weitere 20 Äther synthetisiert, und zwar Glykoläther gleicher Kettenlänge mit Hexyl-, Phenyl-, Cyclohexyl- und Benzylrest sowie isomere Pentaerythritäther mit möglichst großen Unterschieden in der Molekülgestalt bei gleichbleibender Anordnung der polaren Gruppen. Alle Äther—deren Konstitution IR-spektroskopisch gestützt wird — sind ferner so ausgewählt⁵, daß sie in einem experimentell leicht zugänglichen Temperaturbereich (10–90°C) kinematische Viskositäten zwischen 1 und 15 cSt aufweisen.6. Mitt.: Mh. Chem.91, 48 (1960).     

On the lattice stability of metals

The success of perturbation calculations of second order for the NFE (“Nearly Free Electron”) metals and that of the two-parameter model of Pettifor for the transition elements show that the lattice-stability of the metals has simple physical reasons. Using the results of Harrison, Heine and Weaire, Deegan, and Pettifor, a model is developed which allows to explain the stability of the three metal lattices in terms of differences in the potentials. Only those potential differences are considered which are caused by the different packing of the lattices. With the aid of the virial theorem the band structure energy is connected with the potential bandstructure energy. The sequence of stability is predicted to be body centered cubic (bcc), hexagonal close packed (hcp), face centered cubic (fcc) with increasing valence electron concentration. The ranges of stability can be expressed in simple numbers. This simple model holds in principle for NFE as well as for transition metals because it contains no assumptions restricted to only one of these metal types. Deviations of the observed lattice stability from the model can be understood from the approximations involved.     

Stereochemistry of cyclobutanone resulted from cycloadditions of t-butylcyanoketene to bicyclo[2.2.1]heptene derivatives, as evidence for a π2s+π2a reaction mode

The stereochemistry of the cyclobutanones 1-7, resulted from the reaction of t-butylcyanoketene with bicyclo[2.2.1]heptene, bicyclo[2.2.1]heptadiene, 1,4 - dihydro - 1,4 - methanonaphthalene, 1,4 - dihydro - 9 - (1 - methylethylidene) - 1,4 - methanonaphthalene, 1,4 - dihydro - 1,4 - epoxynaphthalene, l,4,4a,8b - tetrahydro - 1,4 - methanobiphenylene (l,4,4a,8b) and 1,4,4a,8b - tetrahydro - 1,4 - methanobiphenylene(1,4,4aβ,8bβ) was established as having the cyclobutanone ring exo and the t-Bu group in the configuration. These findings represent a stereochemical argument in favour of a _π2_s + _π2_a reaction mode of t-butylcyanoketene to the above mentioned bicyclo[2.2.1]heptene derivatives. Observations regarding preservation of the original configurations of alkenes as well as the geometrical distorsion of the cyclobutanones are shortly discussed.     

Potentiostatische Makroelektrolyse einer Reihe von Aryl-polyenketonen und spektroskopischer Nachweis der Produkte

Using data from preparative potentiostatic macroelectrolysis, IR spectroscopy of the isolated products and polarographic data, conclusions are drawn concerning the mechanism of electrode reduction of a series of ,-diphenyl polyene ketones.Electrolysis was carried out in 60% bufferedDMF at three typical pH values causing changes in the mechanism of the electrode process.The data obtained indicate the following scheme for the mechanism of the electrode process: (a) in the strongly acidic region: H⁺, e, H⁺, e; (b) in the intermediate region: H⁺, e, e, H⁺; (c) in the strongly alkaline region: e, H⁺, H⁺, e, H⁺, e.

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Mit 2 Abbildungen     

Fluordiazadiphosphetidine, 3. Mitt.: Die thermische Behandlung von 2,2,2,4,4,4-Hexafluoro-1,3-dimethyl-1,3,2,4-diazadiphosphetidin unter Druck in Gegenwart von Phosphor(V)fluorid und Alkalimetallfluoriden

Prolonged heating of (CH₃NPF₃)₂ in a sealed tube at 120°C yields (CH₃N)₄P₃F₇ and PF₅. Under the experimental conditions these compounds react to (CH₃N)₄P₃F₆ ⁺PF₆ ^–. Reaction of (CH₃NPF₃)₂ in the presence of PF₅ leads to a marked decrease in the formation of the ionic compound. The influence of the fluoride donating saltsMF (M=Li, Na, K, Cs) is investigated.

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Mit 1 Abbildung

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Früher: Alkyliminophosphorsäuretrihalogenide, 1. und 2. Mitt.     

Über einige neue Bispirane

We have obtained four new bispirane systems in which both spiroatoms are vicinal atoms in cyclopropane or cyclobutane rings and in which the heterocyclic component has the basic structure of 1,4-dioxep-2-ene. We have shown that from two possibilities (bispiran, propellan) the general reaction leads only to a bispiran system. To the bispiran2 exhibiting the highest hyperchromism we ascribed the bispirocoplanar conformation (Fig. 1).

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Mit 3 Abbildungen