Sequential transition States and the valley-ridge inflection point in the formation of a semibullvalene

[structure: see text] Two sequential transition states are calculated at the B3LYP/6-31G(d,p) level for the deazetization of 3b. The intrinsic reaction coordinate for loss of nitrogen passes through a transition state and then a valley-ridge inflection point and ultimately leads to the transition state for the Cope rearrangement of semibullvalene 4b. The energetic and geometrical consequences are discussed.     

Zur Kenntnis von Natrium-hexafluoromanganat(III)

Sodium hexafluoromanganate(III) has been synthesized by heating equimolecular quantities of Na₂MnF₅ and NaF in argon atmosphere. The compound is monoclinic witha=5.56 (1) Å,b=5.84 (1) Å,c=8.10 (2) Å, =90.7 (2) andZ=2. It is a high spin complex with _eff and the deformation of the octahedra is evident from its IR-spectra. Two enantiotropic transitions (at 562 and 653°C) and the melting point at 800°C have been observed.

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8. Mitt.: Mh. Chem.106, 483 (1975).     

Discussion on the method for the measurement of the flexural modulus of coupled materials and reasons of the shifts of theQ −1 maxima caused by coupling

Summary When measuringQ ^–1 and the flexural resonance frequency of bars clamped at one end, constituted by a viscoelastic polymeric material glued to a rigid support of modulusE ₁, it is possible to calculate the componentsE ₂ andE ₂ of the complex elastic modulus of the polymeric material examined. In this work the minimum (critical) value of the ratioa=E ₂ /E ₁=a _c and the values of the ratioQ ₂ ^–1/Q ^–1=F ₁ are evaluated beyond which no exact calculation ofE ₂ and ofQ ₂ ^–1 is possible.Within the confidence limits of the linear viscoelasticity theory, these values depend on the accuracy of measurement of both frequency and resonance curve, as well as on the instrument employed, on the operating temperature and on the ratio between the thicknesses of the two coupled materials.In order to keep outside the critical conditions, the most convenient method involves the use of measurements of coupled test-pieces having different ratiosz between their thicknesses and of supports having different modulusE ₁, depending on the field of temperature of the analysis ofE ₂ and tg ₂ concerning and E.P.R. elastomer and a vulcanized cis-1,4 polyisoprene in very wide ranges of temperature comprising the glass transition. Moreover, it is demonstrated by analysis the shift on the temperature axis of the tg maximum of the composite test-piece with respect to the position of the tg maximum of the polymeric material alone.With 11 figures and 1 table     

The continuation of the periodic table up to Z = 172. The chemistry of superheavy elements

The chemical elements up toZ = 172 are calculated with a relativistic Hartree-Fock-Slater program taking into account the effect of the extended nucleus. Predictions of the binding energies, the X-ray spectra and the number of electrons inside the nuclei are given for the inner electron shells. The predicted chemical behaviour will be discussed for all elements betweenZ = 104-120 and compared with previous known extrapolations. For the elementsZ = 121–172 predictions of their chemistry and a proposal for the continuation of the Periodic Table are given. The eighth chemical period ends withZ = 164 located below Mercury. The ninth period starts with an alkaline and alkaline earth metal and ends immediately similarly to the second and third period with a noble gas atZ = 172.

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Zusammenfassung Mit einem relativistischen Hartree-Fock-Slater Rechenprogramm werden die chemischen Elemente bis zur Ordnungszahl 172 berechnet, wobei der Einfluß des ausgedehnten Kernes berücksichtigt wurde. Für die innersten Elektronenschalen werden Voraussagen über deren Bindungsenergie, das Röntgenspektrum und die Zahl der Elektronen im Kern gemacht. Die voraussichtliche Chemie der Elemente zwischenZ = 104 und 120 wird diskutiert und mit bereits vorhandenen Extrapolationen verglichen. Für die ElementeZ =121–172 wird eine Voraussage über das chemische Verhalten gegeben, sowie ein Vorschlag für die Fortsetzung des Periodensystems gemacht. Die achte chemische Periode endet mit dem Element 164 im Periodensystem unter Quecksilber gelegen. Die neunte Periode beginnt mit einem Alkali- und Erdalkalimetall und endet sofort wieder wie in der zweiten und dritten Periode mit einem Edelgas beiZ = 172.

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Resumé Les éléments chimiques jusqu'áZ = 172 sont calculés à l'aide d'un programme Hartree-Fock-Slater relativiste en tenant compte de l'extension du noyau. On fournit des prédictions quant aux énergies de liaison, aux spectres X et au nombre d'électrons dans les noyaux pour les couches électroniques internes. Le comportement chimique prévu est discuté pour tous les éléments entreZ = 104–120 et comparé aux extrapolations connues auparavant. Pour les éléments Z =121–172 on effectue des prévisions de propriétés chimiques et l'on propose un prolongement du Tableau Périodique. La huitième période chimique se termine àZ = 164 sous le mercure. La neuviéme période débute avec un métal alcalin et alcalino-terreux et se termine comme la seconde et la troisième période avec un gaz rare àZ = 172.

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This work has been supported by the Bundesministerium für Wissenschaft und Bildung and by the Deutsche Forschungsgemeinschaft.     

When Ramification points meet

Summary This paper contains three applications of the technique of limit series (our [1986]) to the theory of ramification of linear series on smooth curves, and curves of compact type, overC.Let {L _t t|<}, be a family of linear series on a smooth family of smooth curves {C _t }, and letp ₁(t),p ₂(t)C _t be sections of the family which coincide (only) att=0. Setp=p ₁())=p ₂(0)C ₀.We first give a condition related to the Schubert calculus which must be satisfied by the ramification series and the . We then take up the converse problem: In what ways can a given ramification point arise as a limit? We show that if the ramification point isdimensionally proper in the sense of our [1986], then families of every kind allowed by the Schubert calculus condition can actually be constructed. Finally, we prove that dimensional propriety is in a strong sense an open condition, so that ramification points constructed as above are again dimensionally proper.In the body of the paper we work not with pairs of points, as above, but with arbitrary finite collections of points approaching (possibly) several points of the limit curve. Further, by their nature, the results are valid for families of curves of compact type.     

Sharpness of the phase transition in percolation models

The equality of two critical points — the percolation thresholdp _H and the pointp _T where the cluster size distribution ceases to decay exponentially — is proven for all translation invariant independent percolation models on homogeneousd-dimensional lattices (d1). The analysis is based on a pair of new nonlinear partial differential inequalities for an order parameterM(,h), which forh=0 reduces to the percolation densityP — at the bond densityp=1–e ^– in the single parameter case. These are: (1)MhM/h+M ²+MM/, and (2) M/|J|MM/h. Inequality (1) is intriguing in that its derivation provides yet another hint of a ³ structure in percolation models. Moreover, through the elimination of one of its derivatives, (1) yields a pair of ordinary differential inequalities which provide information on the critical exponents and . One of these resembles an Ising model inequality of Fröhlich and Sokal and yields the mean field bound 2, and the other implies the result of Chayes and Chayes that . An inequality identical to (2) is known for Ising models, where it provides the basis for Newman's universal relation and for certain extrapolation principles, which are now made applicable also to independent percolation. These results apply to both finite and long range models, with or without orientation, and extend to periodic and weakly inhomogeneous systems.Research supported in part by the NSF Grant PHY-8605164Also in the Physics Department     

Wirkungsgrade in der Welt des Lebens und der Technik

Zusammenfassung Um der oft gehörten Meinung entgegenzutreten, die energetischen Wirkungsgrade lebender Organismen seien wesentlich höher als die technischer Verfahren, werden entsprechende Werte miteinander verglichen. Der sehr niedrige Wirkungsgrad der Photosynthese zusammen mit der kleinen Energiedichte der Sonnenstrahlung erzwang ab einer kritischen Größe die Aufspaltung in Energiesammler, die Pflanzen, und Verbraucher chemischer Energie, den Tieren. Dank den 10 mal höheren Wirkungsgraden in der Technik, lassen sich Solarmobile bauen, die von der auf sie fallenden Sonnenstrahlung angetrieben werden. Wegen des Multiplikationsgesetzes der Teilwirkungsgrade ergeben sich sowohl für die Speicherung der Sonnenenergie in den fossilen Brennstoffen wie in der Nahrungskette extrem niedrige Wirkungsgrade.

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Efficiencies in the world of life and in engineering

One often hears the opinion, that the efficiencies in the world of life are higher than in engineering. To disprove this, many values of efficiency of corresponding processes are compared. The very low efficiency of photosynthesis in living plants together with the low density of solar radiation has led the world of life to split into collectors of energy, the plants, and consumers of chemical energy, the animals. Thanks to the ten times higher efficiencies of solar cells, it is possible, to produce solar mobiles, vehicles that move driven by solar radiation.

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Herrn Prof. Dr.-Ing. U. Grigull zum 75. Geburtstag gewidmet     

Further evidence for magnetic charge from meson spectroscopy

Recently evidence was presented for the existence of magnetic charge from Zeeman splitting in meson states. The model by Akers predicted the existence of a new meson at 1814 MeV withI ^G(J ^PC )=0⁺(0^–+). Experimental evidence for this new meson is cited and discussed.