ESR.-Spektrum des Radikal-Anions des [18]Annulen-1,4;7,10;13,16-trisulfids

The ESR spectrum of the radical-anion of [18]annulene-1,4;7,10;13,16-trisulfide (ATS) has been recorded. Its analysis yields six coupling constants for pair of equivalent protons indicating the lack of a threefold symmetry axis. A provisional assignment has been attempted which is based on calculated spinpopulations. Conformations of ATS and ATS^? are shortly discussed.     

Notiz über die Photoelektronen-Spektren des Nortricyclens und des Triasterans

The photocelectron spectra of nortricyclene (=tricyclo[2.2.1.0^2,6]heptane) and of triasterane (=tetracyclo[3.3.1.0^2,8.0^4,6]nonane) have been recorded and a tentative assignment of the bands has been put forward on the basis of MINDO/2 SCF calculations.     

Propriétés thermodynamiques des mélanges binaires. Volume et énergie interne de formation des solutions de l'hexadécane dans les isomères de l'hexane

The volumes of mixing of hexadecane and each of the isomers of hexane have been measured for the equimolar mixtures at 20°C. The results have been used together with previously measured values of ΔH to obtain ΔU_v. A very good correlation is found between the energy of mixing and the properties of the pure alkanes.     

Détermination des chaleurs de mélange des systemes ternaires

Heats of mixing H^E at 303.15 K and 1.013 bar are reported for two ternary liquid mixtures piperidine(1)+n-heptane(2)+cyclohexane(3) and piperidine(1)+n-octane(2)+cyclohexane(3). A Redlich-Kister type smoothing equation was used to represent and correlate the results. A dispersive quasichemical (DISQUAC) theoretical model was used for predicting the heats of mixing H^E at 303.15 K and 1.013 bar for these two ternary liquid mixtures. This revised version was published online in July 2006 with corrections to the Cover Date.     

Thermodynamic excess quantities of ternary Au–Co–Pd melts by computer-aided Knudsen cell mass spectrometry

Computer-aided Knudsen cell mass spectrometry is used for the thermodynamic investigations on ternary Au–Co–Pd melts over the entire range of composition. The “digital intensity-ratio” (DIR)-method has been applied for the determination of the thermodynamic excess quantities, and the ternary thermodynamically adapted power (TAP) series concept is used for algebraic representation of the thermodynamic mixing behavior. The corresponding TAP parameters as well as the values of the molar excess Gibbs energies G^E, of the molar heats of mixing H^E, of the molar excess entropies S^E, and of the thermodynamic activities at 1800 K are presented.     

Untersuchungen an Stickstoff—Jod-Verbindungen. VII. Das IR-Spektrum des Stickstofftrijodid-1-Ammoniaks im Bereich der N–J-Grundschwingungen und Kraftkonstanten der N–J-Bindungen

Studies on nitrogen iodine compounds. VII. The IR spectrum of nitrogen triiodide-1 ammonia in the range of N—I fundamental vibrations and the valence force constants of the N—I bonds New infrared spectra in the region 33—600 cm^?1 of ¹⁴NI₃ · ¹⁴NH₃, ¹⁵NI₃ · ¹⁵NH₃ and ¹⁴NI₃ · pyridine, respectively, have been obtained. In addition, the infrared spectrum of ¹⁴NI₃ · ¹⁴ND₃, which has been prepared for the first time, was obtained. All absorption frequencies can be coordinated on the ground of the molecule model for the NI₃ scaffold with 5 atoms Z₂XY₂ of the symmetry C_2v which has been proved by X ray examination. A set of force constants has been calculated by approximation. The various nitrogeniodine valence force constants are discussed.     

La résonance magnétique du 77Se dans des composés organiques

⁷⁷Se n.m.r. spectra of twenty-six organoselenium compounds, including some with an endocyclic selenium atom, have been recorded. Our measurements complete the scale of chemical shifts previously established by McFarlane. It seems difficult to define a range of chemical shifts which is characteristic of the valency state of selenium or of its endo- or exocyclic position. Some results are discussed qualitatively. In the case of selenolo[2,3-b]thiophene, evidence has been obtained for a ⁴J[Se, H] coupling across the sulphur atom.     

Luminescent Dinuclear Bis‐Cyclometalated Gold(III) Alkynyls and Their Solvent‐Dependent Morphologies through Supramolecular Self‐Assembly

A series of luminescent bis‐cyclometalated gold(III) complexes containing bridging alkynyl ligands of different natures has been synthesised and characterised. The photophysical properties of the complexes have been investigated through electronic absorption spectroscopy and emission studies. The vibronic emission bands are found to originate from the triplet intraligand (IL) π–π* excited states of the bis‐cyclometalating ligands with some mixing of ³IL π–π* character of the alkynyl ligands. The electrochemical study of a nonsymmetric dinuclear complex shows two successive reduction processes originating from the reductions of the two different cyclometalating ligands. The complexes are found to undergo supramolecular self‐assembly processes driven by π–π stacking and hydrophobic/hydrophilic interactions to give honeycomb nanostructures, as revealed from the SEM images. Solvent‐dependent morphological transformations have also been observed, which have been studied by SEM and ¹H NMR spectroscopy.     

Réactions de substitution nucléophile de l'hydroxyurée. Synthèse et étude des oxa-6 dihydrouraciles

Hydroxyurea, an N-protected hydroxylamine, reacts with α-bromoesters to give α-ureidoxyesters. Some of these have been isolated. Their cyclisation is a synthetic route to 6-oxadihydrouraciles which structure has been well established by means of physicochemical methods. Especially, ¹³C nmr spectroscopy has been used to show only the presence of the diketone tautomeric form.     

Über Triphosphorsäurederivate des Cyanamids und des Harnstoffs

Triphosphoric Acid Derivatives of Cyanamide and Urea Cyanamidotriphosphate, P₃O₉NCN^5? ( I ), is obtained by ring opening reaction of the cyclotriphosphate ion, P₃O₉^3?, by cyanamide in alkaline solution. As a pseudochalcogeno-substituted triphosphate, I has similar properties like the triphosphate, P₃O₁₀^5? (Ca²⁺ sequestering; behaviour on acidimetric titration; X-ray powder diffraction of the sodium salt hydrates). In acidic solution I decomposes forming ureidotriphosphate with the anion P₃O₉NHCONH₂^4? ( II ) which cannot be directly obtained from cyclotriphosphate and urea. II is characterized by its chemical analysis, by paper chromatography, by its behaviour in acidic solution and by its IR and ³¹P-NMR spectra. Solid salts of I and II are prepared and the data of their Guinier diagrams are communicated.     

Etude RMN 13C d'un Dérivé Uniformément Enrichi en 13C. Signe des Valeurs des Constantes de Couplage Observées

The ¹³C NMR parameters of 3-O-acetyl-1,2:5,6-di-O-isopropylidène-α-D-[U-¹³C] glucofuranose, used as a sample for analysis in double labelling biosynthetic experiments, have been measured. Homonuclear double resonance experiments ¹³C? {¹³C} at 62.8 MHz have permitted the determination of all the ¹³C? ¹³C coupling constants. By theoretical computation of spectra, in connection with the second order effects existing at 25.2 MHz and 15.08 MHz, the sign of the coupling constants has been determined. The theoretical computation of spectra took into account all the isotopomers and was calculated with the help of a program (adapted from the LAOCOON program) allowing for the weighted addition of the spectra.     

Spectres de masse des composés organiques. 5e communication. Perte de méthane et d'éthylène à partir des ions butyle

The loss of methane and ethylene in the mass-spectrometric fragmentation of different isomeric butyl ions which originate from butyl halides has been studied. The different carbon atoms in n-butyl are already equivalent after 10^?7 s, whereas the statistical distribution of the hydrogen atoms within the molecule can only be observed for the metastable peaks. A protonated cyclobutane structure is proposed as an intermediate product in the fragmentation of the n-butyl ion. The fragmentation of this model has been simulated by a computer. This allows prediction as to the time-scale of fragmentation. The comparison of this model fragmentation with that of isomeric butyl ions shows that, even in the decay of the tertiary butyl ion, the formation of the proposed rearranged cyclic structure competes favorably with the direct fragmentation.     

Détermination par RMN 1H et 13C de la Conformation Favorisée des Ozonides d'Acènes

The preferred conformation of 9,10-dimethylanthracene ozonide has been established by ¹³C and ¹H NMR. Results hold for other anthracenic ozonides such as those of 9,10-dimethoxyanthracene and anthracene. The latter compound, resulting from the ozonolysis of anthracene, has for the first time been shown to exist in solution.     

Stereochimie de la des benzoates d'argent sur des diesters iododesoxy ns: I- Action des benzoates d'argent sur des di-o-aroyl-1,2 iododesoxy-3 ns-glycerols

The stereochemistry of the reaction of silver benzoates on chiral di-O-aroyl-1,2 iododeoxy-3-sn-glycerols has been reinvestigated. The reaction proceeds either with or without neighbouring group participation, depending on : - possible electrophilic assistance by the silver ion to the ionisation of the substrate (occuring only with dissociated silver salts), - ability of substituants R¹ and R² on the substrates to stabilize a positive charge. Rearrangements are at minimum with R¹ and R² electronreleasing groups in the substrate, silver salts un-or weakly dissociated and bearing a good nucleophile. For one case, a regio- and stereo specific reaction is observed.     

Alcoylation des enolates de l'acetylacetate d'ethyle dans le dimethoxyethane. Reactivite des formes associee et dissociee

The alkylation of alkali metal and N⁺Bu₄ ethylacetoacetate énolates by means of ethyl iodide, bromide and tosylate has been studied in diméthoxyéthane, in order to measure the reactivity of the associated forms. C/O alkylation ratios, structures of O-alkylated products and rates of alkylation, have been determined. With ethyl tosylate, the amount of O-alkylated products does not increase in the generally observed order Li⁺ < Na⁺ < K⁺ < Cs⁺ but in the order Na⁺ < K⁺ < Li⁺ ≈ Cs⁺. Some aspects of the alkali ethylacetoacetate énolates reactivity in weakly polar medium such as DME are discussed.     

Zusammensetzung und strukturelle Eigenschaften des „zweiwertigen”︁ Kobaltcyanids

The products obtained by mixing aqueous solutions of cobalt (II) chloride and potassium or hydrogen cyanide are nonstoichiometric compounds Co(CN)_x, yH₂O whith x between 2.2 and 2.4 and y between 1.75 and 2.15. They have a cubic face-centered unit cell with a = 10.20 ± 0.02 Å and Z between 6.8 and 7.1 (Z = number of units Co (CN)_x yH₂O per cell). Infrared spectra show that there is zeolitic as well as coordinated water present. The coordination units derived from reflectance spectra in the ultraviolet and visible region are (Co^III)C₆ and Co^IIN_6-xO_x. There exists a close structural relationship between Co(CN)_x, yH₂O and the stoichiometric compound Co₃[Co(CN)₆]₂, zH₂O. Comparison of calculated with experimental density shows that there must be holes in the threedimensional Co? C? N? Co-framework, which can be occupied by water molecules.     

Etude structurale de l'hydruro-oxyde LaHO par diffraction des rayons X et par diffraction des neutrons

The hydride-oxide LaHO crystallizes with a fluorite superstructure. The unit cell is tetragonal, space group $\text{P4}\text{nmm}\text{, a = 8,074(1)}$ Å, c = 5,739(1) Å, and Z = 8. The structure has been determined by two complementary techniques: X-ray and neutron diffraction. The La³⁺ ions are situated in the center of cubes at the corners of which four O^2? and four H^? are placed, there exist three different types of environment according to the distribution of the two anion species (the anions of the same type form either a tetrahedron or occupy a face or a diagonal plane of the cube). The LaO(H) distances observed are discussed by taking into account the relationship which exists between bond strength and bond length. The average value of d 〈OH〉 is 2,85 Å, which is rather unusual. It confirms that we are indeed dealing with a hydride-oxide simultaneously associating the O^2? and H^? ions in a ternary combination. Through energy considerations (electrostatic site potential and lattice potential), the structural arrangement of LaHO is compared to that encountered in the case of the homologous lanthanum oxifluorides.     

Die Konstitution des Alkaloides Juliprosopin aus Prosopisjuliflora A. Dc. 176. Mitteilung über organische Naturstoffe

The Structure of the Alkaloid Juliprosopine from Prosopis juliflora A. Dc. A new alkaloid, juliprosopine, has been isolated from Prosopis juliflora A. Dc. (Leguminosae), for which structure 1 is proposed. The piperidine moiety could be elucidated on the basis of spectroscopic data (MS., ¹H-NMR., ¹³C-NMR.) of juliprosopine and the derivatives 2–4 . The central hexahydroindolizine part and its substitution pattern has been determined mainly on the bases of the Hofmann-degradation product 11 , which yielded the hydrogenation products 13 and 14 . By ozonolysis 11 was converted to 16 and 18 . It is proposed that juliprosopine was built up in nature by two ‘monomeric’ Prosopis alkaloids and one dihydropyrrol unit.     

Migration électrolytique d'ions argent radioactifs dans des macrocristaux de bromure d'argent

A cylindrical disk of macrocrystalline silver bromide marked on one side with radioactive silver ions (^110mAg) has been used as a diaphragm for electrolysis between two cells filled with water in which two platinum electrodes were immersed.     

Etude du mecanisme de l'hydrolyse alcaline des N-methyl acetanilides au moyen des effets de milieu

N-methyl acetanilides alkaline hydrolysis mechanism has been studied by means of solvent effect (DMSO and ²H₂O) and of structure-reactivity correlation (log k_obs = f(pK_{B aniline})). Our results are consistent with HO^? rate determining attack only for p-nitro anilide and with a rate determining water assisted decomposition of the tetrahedral intermediate for X  p-CH₃O, H, p-Cl, m-Cl.