First structurally characterized actinide isocyanates

The synthesis and characterization of the neutral uranylisocyanate UO(2)(NCO)(2)(OP(NMe(2))(3))(2) [crystal data: monoclinic, P2(1)/c, a = 8.512(2) A, b = 10.931(2) A, c = 14.329(3) A, beta = 103.923(3) degrees , V = 1294.0(4) A(3), Z = 2] and isocyanato uranate (Et(4)N)(6)[(UO(2))(2)(NCO)(5)O](2) x 2CH(3)CN x H(2)O [crystal data: monoclinic, P2(1)/c, a = 17.2787(2) A, b = 15.560(1) A, c = 32.7619(4) A, beta = 94.0849(5) degrees , V = 8786.5(2) A(3), Z = 4] are reported. Not only are these compounds the first unambiguously characterized uranium isocyanates regardless of the oxidation state for uranium, but they are also the first structurally characterized actinide isocyanates. Both compounds show coordination of the OCN moiety through nitrogen to uranium and were characterized using IR and (1)H, (13)C, (14)N, and (31)P NMR spectroscopy and X-ray diffraction.     

Synthesis and Extraction Studies of a Versatile Calix[4]arene-Based “Proton-Switchable Extractant” for Toxic Metals and Dichromate Anions

The article describes the syntheses and extraction properties of a new calixarenebased extractant 5, which has been synthesized from5,11,17,23-tetra-tert-butyl-25,27-bis(chlorocarbonyl-methoxy)-26,28-dihydroxycalix[4]arene(4) by treatment with isoniazid (isonicotinic acid hydrazide) in the presence ofpyridine. The compound 5 was converted to its methyl iodide salt (6) by refluxing 5 with methyl iodide in acetonitrile. In this synthesis it was thought to explore the role of pyridinium sites in the extraction of HCr₂O ₇ ^- /Cr₂O ₇ ^2- anions. The complexing properties of 5 toward selected alkali/transition metal cationsand HCr₂O ₇ ^- /Cr₂O ₇ ² - anions are reported. It has been observed that receptor 5 does not extract alkali metal cations but shows an excellent selectivity toward transition metals. The protonated pyridinium form of 5 is an effective formfor transferring the HCr₂O ₇ ^- /Cr₂O ₇ ^2- anions from an aqueous into adichloromethane layer.     

Selective fluorination of dispiro[3.1.3.1]decan-5,10-dione by diethylaminosulfurtrifluoride to give 10,10-difluorodispiro[3.1.3.1]decan-5-one and 5,5,10,10-tetrafluorodispiro[3.1.3.1]decane

Dispiro[3.1.3.1]decan-5,10-dione was selectively difluorinated at room temperature by diethylaminosulfur trifluoride (DAST) to give 10,10-difluorodispiro[3.1.3.1]decan-5-one. The latter was reduced to 5,5-difluorodispiro[3.1.3.1]decane and also reacted with excess DAST to give 5,5,10,10-tetrafluorodispiro[3.1.3.1]decane. Proton and fluorine magnetic resonance studies on 5,5-difluorodispiro[3.1.3.1]decane did not show significant cross-ring coupling (< 0.5 Hz) between geminal fluorines on C-5 and geminal hydrogens on C-10. The fluorine magnetic resonance spectrum of 5,5,10,10-tetrafluorodispiro[3.1.3.1]decane was a single sharp line which establishes that through-space coupling between geminal fluorines at C-5 and C-10 and geminal hydrogens on other carbons does not exist. A study of the infrared and ultraviolet spectra of dispiro[3.1.3.1]-decane-5,10-dione indicate the cross-ring carbonyl groups interact significantly.     

Comprehensive two-dimensional gas chromatography coupled to a rapid-scanning quadrupole mass spectrometer: principles and applications

The principles, practicability and potential of comprehensive two-dimensional (2D) gas chromatography coupled to a rapid-scanning quadrupole mass spectrometer (GC x GC-qMS) for the analysis of complex flavour mixtures in food, allergens in fragrances and polychlorinated biphenyls (PCBs) were studied. With a scan speed of 10,000 amu/s, monitoring over a mass range of up to 200 atomic mass unit (amu) can be achieved at an acquisition frequency of 33 Hz. Extending this mass range and/or increasing the data acquisition frequency results in a loss of spectral quality. Optimal parameter settings allow, next to unambiguous identification/confirmation of target compounds on the basis of high-quality mass spectra, fully satisfactory quantification (three to four modulations per peak) with linear calibration plots and detection limits in the low-pg level. The potential of time-scheduled data acquisition to increase the effective mass range within one GC x GC run was also explored. The analyses, with baseline separation of the flavours, allergens and PCB target compounds, took less than 30 min.     

Efficient copper-mediated reactions of nitrenes derived from sulfonimidamides

[reaction: see text] Sulfonimidamides lead efficiently to nitrenes and have been converted to sulfimides, sulfoximines, and aziridines in good yields, through a copper-mediated multicomponent reaction. The stereogenic sulfur atom and the trivalent nitrogen atom present in the molecules open the way to asymmetric synthesis, whose first results are presented.     

Ligandbewegungen in űbergangsmetallkomplexen XI 1H-NMR-spektroskopische untersuchungen an acetylacetonat-bis(olefin)-rhodium(I)-komplexen

The temperature-dependent ¹H NMR spectra of acetylacetonatebis(ethylene)-rhodium, (acac)Rh(C₂H₄)₂ (I), of some related complexes containing methoxy-substituted ethylenes have been measured in toluene-d₈ solution. Both monosubstituted [(acac)Rh(C₂H₄)(olefin), olefin = tetramethoxyethylene (II), $\text{cis}$- and $\text{trans}$-dimethoxyethylene (III and IV)] and disubstituted [(acac)Rh(olefin)₂, olefin = $\text{cis}$- and $\text{trans}$-dimethoxyethylene (V and VI), methyl vinyl ether (VII)] derivatives of I have been investigated with respect to hindered intramolecular movements of the ligands. The barriers of olefin rotation increase with an increasing number of methoxy substituents. When the olefin rotation is frozen out; the methoxy substituents of the olefins tend to be turned away from the acetylacetonate ligand unless steric interaction occurs between the two π-coordinated olefins. A hindered movement of the acetylacetonate ligand has been observed in II and V. For this movement which is independent of the olefin rotation, a degenerate rearrangement is proposed of the tetragonal-planar complexes via a tetrahedral transition state.     

Synthese einiger 8-substituierter 2-Methyl-1,2,3,4-tetrahydroisochinoline

Synthesis of Some 8-Substituted 2-Methyl-1,2,3,4-tetrahydroisoquinolines A general route to 8-substituted tetrahydroisoquinolines is exemplified by the preparation of the 2-methyl-1,2,3,4-tetrahydroisoquinolin-8-ol ( 11 ), the -8-carbaldehyde oxime ( 12 ) and the -8-carbonitrile ( 13 ). It involves the conversion of isoquinoline ( 1 ) by partially modified Steps 1, 2, 3, and 5 (see the Scheme) into the 5-bromo-8-nitro derivative 5 , reduction of the latter to the 8-amino derivative 8 and replacement of the NH₂-group with an appropriate substituent by a Sandmeyer-like reaction. The selective reductions of the N-containing ring in 6 (Steps 5, 6, and 8) and of the NO₂-group in 5 (Steps 4 and 7) were also studied.     

Die Trennung des Kobalts von Nickel mit Anionenaustauschern und die photometrische Bestimmung des Kobalts als Cyanatkomplex

Zusammenfassung Die rasche Sorbierbarkeit des Kobalts als anionischem Kobalt(II)-cyanatkomplex an ruhendem oder bewegtem Austauscher Dowex 1X8 erlaubt Trennungen Kobalt/Nickel für das Verhältnis 150. Die anschließende photometrische Bestimmung des Kobalts als Cyanatkomplex bei 620 m ist bequem durchführbar, nachdem das Kobalt mit Salzsäure eluiert worden ist.Herrn Prof. Dr. O. Glemser, Direktor des Instituts, danken wir für stete Förderung der vorliegenden Untersuchungen.Dem Herrn Bundesminister für Atomkernenergie und Wasserwirtschaft, sowie der Deutschen Forschungsgemeinschaft danken wir für Unterstützung.     

Mikrogravimetrische Bestimmung von Gold als Dekamethonium-Tetrabromoaurat(III)

Zusammenfassung Die mikrogravimetrische Bestimmung von Gold als Bis(trimethyl)-dekamethylendiammoniumtetrabromoaurat(III) [(CH₃)₃N-(CH₂)₁₀-N(CH₃)₃] [AuBr₄]₂ erlaubt die Erfassung von 700g Au neben 200fachen Überschüssen an Cu²⁺ und Ni²⁺ sowie 50fachen Mengen anderer Übergangsmetalle.

---

Summary The microgravimetric determination of gold as bis-(trimethyl) decamethylenediammoniumtetrabromaurate(III) [(CH₃)₃N-(CH₂)₁₀-N(CH₃)₃] [AuBr₄]₂ permits the determination of 700g Au in the presence of 200-fold excesses of Cu²⁺ and Ni²⁺ as well as 50-fold amounts of other transition metals.

---

Résumé Le microdosage gravimétrique de l'or à l'état de tétrabromoaurate-III de bis(triméthyl)décaméthylènediammonium [(CH₃)₃N-(CH₂)₁₀-N(CH₃)₃] [AuBr₄]₂ permet de descendre jusqu'à 700g Au en présence d'un excès de 200 fois Cu²⁺ et Ni²⁺ et d'une quantité 50 fois plus grande des autres métaux de transition.