Reaction of styrene with sulfur and triiron dodecacarbonyl and the molecular structure of the complex Fe2(CO)6(SCH2S)

Reaction of excess styrene with Fe₃(CO)₁₂ and sulfur (60°C, 15 h, Ar, S/Fe₃(CO)₁₂ 0.6 g-atom/mole) gave Fe₂(CO)₆S₂, Fe₃(CO)₉S₂, Fe₂(CO)₆(S₂CO), Fe₂(CO)₆S₂(PhCHCH₂), PhCHCH₂S₄, and a novel binuclear complex Fe₂(CO)₆(S₂CH₂S), whose structure was analyzed by x-ray crystallography. The crystals are monoclinic, a=7.764(3), b=13.205(4), c=6.628(6) Å, =98.97(3)°. V=671.2(7) ų, Z=2, space group P2₁/m. The bond lengths are Fe-Fe 2.520(2), Fe-S 2.236(2), S-S 2.078(4), C-S 1.825(12), Fe-CO 1.784(8), and CO 1.148(9) Å.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 930–934, April, 1991.     

Ligand exchange reactions of ferrocene with phenanthrene or 9,10-dimethylphenanthrene in the presence of aluminum chloride and aluminum

Ligand exchange reactions between phenanthrene or 9,10-dimethylphenanthrene with ferrocene effected in the presence of AlCl₃-Al were carried out under a variety of conditions. With phenanthrene (I), hydrogenation at the C-9 and C-10 positions could take place during the reaction and the cationic products obtained were the η⁶-phenanthrene-η⁵-cyclopentadienyliron and η⁶-9,10-dihydro-phenanthrene-η⁵-cyclopentadienyliron moncations (II and III), and the η⁶-phenanthrene-$\text{trans}$-$\text{bis}$-η⁵-cyclopentadienyliron and η⁶-9,10-dihydrophenanthrene-$\text{trans}$-$\text{bis}$-η⁵-cyclopentadienyliron dications (IV and V). With 9,10-dimethylphenanthrene (VI), reactions carried out in refluxing cyclohexane gave the non-hydrogenated η⁶-9,10-dimethylphenanthrene-η⁵-cyclopentadienyliron monocation (VII) and η⁶-9,10-dimethylphenanthrene-$\text{trans}$-$\text{bis}$-η⁵-cyclopentadienyliron dication (VIII). When higher temperatures were used in an attempt to promote hydrogenation, decomposition predominated and no cationic product could be obtained. These finding are discussed and contrasted with previous results obtained from similar reactions using anthracene or 9,10-dimethylanthracene.     

1,2,4-Triazine and triazole derivatives from α-keto acids and thiosemicarbazides

Thiosemicarbazides of 2-hydroxyphenylglyoxylic acid, which, depending on the conditions, undergo cyclization to interconvertible 5-(2-hydroxyphenyl)-6-oxo-1,2,4-triazine-3-thiones or (2-hydroxy-benzoyl)-²-1,2,4-triazoline-5-thiones, are formed by the action of thiosemicarbazide and its homologs on coumarindione. The thiosemicarbazones of 2-hydroxyphenylglyoxlyic and other 2-substituted phenylglyoxylic acids undergo cyclization to 6-(2-hydroxyphenyl)-5-oxo-1,2,4-triazine-3-thiones.Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp, 116–121, January, 1977.     

Determination of metal traces in tantalum by proton activation analysis

Procedures for determining traces of calcium, titanium, vanadium, chromium, iron, copper, niobium, molybdenum and tungsten in tantalum are described utilizing 11 MeV proton activation. The instrumental method of analysis with the use of a Ge(Li) detector and the radiochemical separation of the corresponding fractions are described. The formula for the calculation of the concentration of traces with the use of thick target yields is given. Experimental data on the thick target yields of radioisotopes⁴⁴Sc,⁵²Mn,⁵⁶Co,⁶⁵Zn,^93mMo,⁹⁶Tc are presented. Based on the experimental data, the detection limits are estimated at 1–10 ppb for the above mentioned metal traces in tantalum. The successful solution of the task of the simultaneous determination of nine elements in tantalum confirms the wide applicability of proton activation analysis.     

New sesquiterpenoids from the sponge axinella cannabina

The structures of three sesquiterpenoids, axisothiocyanate-2(4), axamide-1(5) and axamide-2(6), present in the marine sponge Axinella cannabina, have been determined on the basis of chemical and spectral evidences.     

Pyridazines. LXV. Reactions of some I-phenacylazolopyridazinium halides with 2,3-diphenylcyclopropenone, -thione,or hydrazine

I-Phenacylazolopyridazinium bromides reacted with 2,3-diphenylcyclopropenone or -thione in the presence of triethylaminc to give 3,4,6-triphenyl-2-pyrone or -2-thiopyrone and the corresponding azolopyridazine. Quaternized azolopyridazines reacted with hydrazine to give either 3,6-diphenylpyridazine and the corresponding azoloazine or hy ring opening of the azine part to give 1-methyl-2-(pyrazolyl-5′)imidazole.     

Der Einfluß von Vanadin und Niob auf feste Subcarbidlösungen in den Systemen Tantal-Wolfram-Kohlenstoff und Tantal-Molybdän-Kohlenstoff

Zusammenfassung Röntgenbeugungsfilme von Pulveraufnahmen wärmebehandelter Proben wurden zur Untersuchung der Phasengleichgewichte der pseudo-ternären Subcarbidsysteme Ta₂C–Mo₂C(W₂C)–V₂C(Nb₂C) bei 1650° und 2000°C herangezogen. Es werden in jedem System die Zusammensetzungs-bereiche festgestellt, in denen die bekannte Disproportionierungsreaktion zu erwarten ist. Es ist dies ein erster Schritt, um zu ermöglichen, diese Legierungen zur Herstellung von Schneide-werkzeugen heranzuziehen. In allen Systemen bilden die Subcarbidphasen ausgedehnte Einphasenbereiche. In den Nb₂C enthaltenden Systemen gibt es Legierungen mit engen Zusammensetzungsbereichen, die möglicherweise als Legierungen für die Erzeugung von Schneidewerkzeugen herangezogen werden können.

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The effect of vanadium and niobium on the subcarbide solid solution in the tantalum-tungsten-carbon and tantalum-molybdenum-carbon systems

The phase equilibria of the pseudo-ternary subcarbide systems Ta₂C–Mo₂C(W₂C)–V₂C(Nb₂C) at 1650 and 2000°C have been investigated using X-ray powder diffraction films of heat treated samples. The compositional regions in each system where the known disproportionation reaction is expected to occur have been defined as an initial step towards the utilization of these alloys for cutting tools. The subcarbide phases form extended single phase regions in all systems. Alloys from small compositional regions in those systems containing Nb₂C are possible candidates for preliminary cutting tool alloy evaluation.

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Mit 4 Abbildungen

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Herrn Prof.H. Nowotny gewidmet.     

Existence of a photodecolorization reaction of the colored form of spiropyrans under the influence of initiating UV irradiation

The kinetics of photochromic transformations of spiropyrans of the indole series with various substituents in the 1 and 5 positions were studied. The existence of a photodecolorization reaction under the influence of activating UV light was proved, and the effect of substituents on the quantum yields of the photocoloration and photodecolorization reactions was studied.     

Synthese und Konfiguration von Methylestern der diastereomeren (±)-3-Amino-2,3-diarylpropansäuren,der (±)-3-Amino-2,3-diarylpropanole und ihrer Derivate

Zusammenfassung Durch Umsetzung von Hydramiden mit am aromatischen Ring m,p-dialkoxysubstituierten Arylessigsäureestern in Gegenwart von wasserfr. AlCl₃ entstehen Gemische aus Estern der (±)-erythro- und (±)-threo-3-Amino-2,3-diarylpropansäuren. Bei der Umsetzung von Piperonalhydramid mit dem Methylester der Homoveratrumsäure konnte lediglich daserythro-Diastereomere isoliert werden.Die diastereomeren Ester wurden zu den jeweiligen (±)-erythro- und (±)-threo-3-Amino-2,3-diaryl-1-propanolen reduziert, die als N,O-Dibenzoylderivate charakterisiert wurden. Ihre relativen Konfigurationen und die der zugehörigen Ester wurden auf Grund der IR-Spektren der diastereomeren Aminopropanole bestimmt. Die NMR-Spektren eines Diastereomerenpaares von Aminopropanolen bestätigen die ihnen chemisch zugeordneten Konfigurationen und ermöglichen den Nachweis auch ihrer bevorzugten Konformationen.

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Synthesis and configuration of methyl esters of the diastereomeric (±)-3-amino-2,3-diarylpropanoic acids, the (±)-3-amino-2,3-diaryl-1-propanols and their derivatives

Reaction of hydramides with m,p-dialkoxysubstituted arylacetates in the presence of anhydrous AlCl₃ generally leads to mixtures of the esters of the (±)-erythro- and (±)-threo-3-amino-2,3-diarylpropanoic acids. However, in the reaction of piperonal hydramide with methyl homoveratrate, only the correspondingerythro-diastereomer was obtained.Reduction of the diastereomeric esters gives the corresponding (±)-erythro- and (±)-threo-3-amino-2,3-diaryl-1-propanols, which can be characterized as N,O-dibenzoyl derivatives. Relative configurations of both alcohols and esters were determined by means of their IR spectra. Configurations were confirmed for one pair of diastereomeric amino alcohols by means of NMR spectra and preferred conformations deduced.

     

Some symmetry-induced isotope effects in the kinetics of recombination reactions

Symmetry-induced isotope effects in recombination and collision-induced dissociation reactions are discussed. Progress on understanding the anomalous isotope effects in ozone is reviewed. Then, calculations are performed for the simpler reaction xNe+yNe+H<-->xNeyNe+H, where x and y label either identical or different isotopes. The atomic masses in the model are chosen so that symmetry is the only difference between the systems. Starting from a single potential energy surface, the properties of the bound, quasibound, and continuum states of the neon dimer are calculated. Then, the vibration rotation infinite order sudden approximation is used to calculate cross sections for all possible inelastic and dissociative processes. A rate constant matrix that exactly satisfies detailed balance is constructed. It allows recombination to occur both via direct three-body collisions and via tunneling into the quasibound states of the energy transfer mechanism. The eigenvalue rate coefficients are determined. Significant isotope effects are clearly found, and their behavior depends on the pressure, temperature, and mechanism of the reaction. Both spin statistics and symmetry breaking produce isotope effects. Under most conditions the breaking of symmetry enhances the rates, but a wide spectrum of effects is observed; they range from isotope effects with a normal mass dependence to huge, mass-independent isotope effects to cancellation and even to reversal of the isotope effects. This is the first calculation of symmetry-induced isotope effects in recombination rates from first principles. The relevance of the present effects to ozone recombination is discussed.