Crystal structure of isotactic poly(4-methyl-1-pentene)

The crystal structure of isotactic poly(4-methyl-1-pentene) was determined by x-ray analysis. The unit cell is tetragonal, P4 b2, with α = 18.70 Å and c (fiber axis) = 13.68 Å; it contains four molecular chains each consisting of seven monomeric units in the fiber period. The molecular conformation is essentially a (7/2) helix, but deviates slightly from the uniform (7/2) helix. The unusual low density is discussed from the structural point of view.     

Low-lying levels in 120Sb studied with the 120Sn(p,nγ) reaction

Properties of the levels in ¹²⁰Sb have been studied with the reaction ¹²⁰Sn(p, nγ). The low-lying level scheme of ¹²⁰Sb below 450 keV was constructed from the γ-ray excitation functions and γ-γ coincidences. The spins and parities were assigned from comparisons of the measured angular distributions and linear polarizations of the deexciting γ-rays as well as the absolute excitation functions of the residual levels with the predictions of the statistical compound nucleus model. In addition, the half-life of an isomeric state at 78.15 keV was measured. The results are 8.37 keV, 2^?; 78.15 keV, 3⁺; $\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{= 241±3}\text{ns}$; 149.29 keV, 3⁺; 166.05 keV, 3^?; 192.64 keV, 2⁺; 233.06 keV, 2⁺; 243.80 keV, 4; 260.29 keV, 3^?; 261.68 keV, 4; 334.07 keV, 4; 341.14 keV, 5; 343.21 keV, 4; 390.31 keV, 2 or 3⁺; 437.68 keV, 1 or 2 and 447.68 keV, 1⁽⁺⁾.     

Infrared band intensities and the complete quadratic force field for planar vibrations of gaseous benzene

Infrared absolute band intensities of the planar fundamental modes were measured for benzene and its deuterium homologs in the gas phase, and were successfully interpreted in terms of effective charges and charge flux parameters. The charge flux parameters were determined from the intensities by taking the effective charge on the hydrogen atom of benzene to be 0.125 e, a value which had previously been obtained from the nonplanar modes. The parameters determined were found to be quite consistent with those of other molecules. The complete quadratic planar force field of benzene was also introduced, the 273 assigned frequencies having been reproduced with a root-mean-square difference of 2.9 cm^?1.     

Trace determination of iodide by derivatization and electron-capture gas chromatography

Summary A simple, sensitive and specific method is described for the determination of iodide as pentafluorobenzyl iodide, based on the chemical derivatization of iodide anion with pentafluorobenzyl bromide. The derivative formed in the reaction solution was directly analyzed, without further pretreatment, by gas chromatography with an electroncapture detector. The detection limit was about 1 ng of iodide anion in 0.10 ml of aqueous sample analyzed. Interferences of some common anions with the method were investigated and were proved to be minimal. It was demonstrated that the proposed method is applicable to the determination of iodide in spring water.

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Bestimmung von Iodidspuren durch Derivatisierung und Electron-Capture GC

Zusammenfassung Eine einfache, empfindliche und spezifische Methode wird beschrieben zur Iodidbestimmung als Pentafluorbenzyliodid, die auf der Reaktion von Iodid mit Pentafluorbenzylbromid beruht. Das gebildete Derivat wird direkt ohne weitere Vorbehandlung der GC mit Electron-Capture-Detektion unterworfen. Die Nachweisgrenze liegt bei etwa 1 ng Iodid in 0,1 ml. Störungen durch andere Anionen wurden untersucht und erwiesen sich als unbedeutend. Das Verfahren wurde zur Iodidbestimmung in Quellwasser angewendet.

     

The phosphorescent states of pentachlorobenzene, 1,2,3,4- and 1,2,3,5-tetrachlorobenzenes

The symmetries of the vibrations appearing in the phosphorescence spectra of C_2v molecules, pentachlorobenzene, 1,2,3,4- and 1,2,3,5-tetrachlorobenzenes are assigned with the aid of optically detected magnetic resonance. It is found that the vibration which softens the Cl…Cl repulsion, in addition to C-Cl out-of-plane vibrations, plays an important role in the radiative properties of pentachlorobenzene in the triplet state.     

Dirhodium(II) tetrakis[N-tetrachlorophthaloyl-(S)-tert-leucinate]: a new chiral Rh(II) catalyst for enantioselective amidation of C---H bonds

Dirhodium(II) tetrakis[N-tetrachlorophthaloyl-(S)-tert-leucinate], characterized by substitution of chlorine atoms for four hydrogen atoms on the phthalimido group in the parent dirhodium(II) complex has been found to be well suited for enantioselective amidation of benzylic C---H bonds with [(4-nitrophenyl)sulfonylimino]phenyliodinane. The observed enantioselectivity of up to 84% ee is the highest reported to date for dirhodium(II) complex-catalyzed C---H amidations.