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1982 (310)
61Author    Gemot Frenking, Jochen Schmidt, Helmut SchwarzRequires cookie*
 Title    Quantenmechanische Berechnungen zu pseudo-einstufigen (C-C)-Spaltungen bei Radikalkationen von Carbonsäuren Quantum Mechanical Calculations on Pseudo-One-Step Cleavages of Carbonic Acid Cation Radicals  
 Abstract    Extensive quantum mechanical calculations on the unrestricted MINDO/3 level reveal that for some ionised carbonic acids the energetically most feasible pathway for uni-molecular C-C cleavage cannot be described as being a one-step process. In complete agreement with experimental results the computational data are consistent with an inter-pretation of the reaction as being a two-step process, in which the reaction commences with a hydrogen migration from a CH-bond onto the ionised C = 0 group. The dissociation is completed with a radical induced C-C cleavage thus generating quite stable protonated unsaturated carbonic acids. Whereas the MINDO/3 results clearly show that the two-step process is energetically favoured over the direct C-C cleavage, this computational method fails badly in explaining the experimentally established fact that in the two-step sequence the hydrogen migration is the rate-determining step. This failure is due to the MINDO/3 inherent weakness of overestimating the stability of cyclic ions, e.g. cyclic transition states as they are formed in the course of the hydrogen migration step. Single point ab initio calculations carried out on the 4-31G level substantiate this interpretation in that the transition state for the hydrogen migration is calculated to lie substantially higher than that for the actual C-C dissociation step, but is still much lower than that calculated for a direct simple bond cleavage process of the respective cation radical. 
  Reference    Z. Naturforsch. 37b, 355—360 (1982); eingegangen am 23. Oktober 1981 
  Published    1982 
  Keywords    Potential Energy Surfaces, Carbonic Acids, Hydrogen Rearrangement, C-C Cleavage, Mass Spectrometry 
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 Identifier    ZNB-1982-37b-0355 
 Volume    37 
62Author    Klaus Burger, Friedrich Hein, Joachim FirlRequires cookie*
 Title    Vom "criss-cross"-Schema abweichende Cycloadditionsreaktionen an das Azin-System [1] Zum Cycloadditionsverhalten von Hexafluoracetonazin gegenüber N.N-Dialkyl-cyanamiden [2] Cycloaddition Reactions of Azines Violating the "criss-cross" Cycloaddition Scheme [1] Cycloaddition Behaviour of Hexafluoroacetone Azine towards N,N-Dialkyl-cyanamides [2]  
 Abstract    Cycloaddition Reactions, Trifluoromethyl Substituted Heterocyclic Systems, Long Range Coupling 9 JFF Depending upon the molar ratio of the educts and the reaction conditions used, hexa-fluoroacetone azine (1) reacts with N,N-dialkyl-cyanamides (2) to give 3,4,6-triazaocta-2,4,6-trienes (6) and/or 4,4-bis(trifluoromethyl)-l,4-dihydro-l,3,5-triazines (7). Cyclo-addition reactions of 6 with teri-butyl isocyanide and l-diethylamino(propine) are de-scribed. IR, *H, 19 F, and 13 C NMR data of the new compounds are discussed. 
  Reference    Z. Naturforsch. 37b, 361—367 (1982); eingegangen am 11. August 1981 
  Published    1982 
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 Identifier    ZNB-1982-37b-0361 
 Volume    37 
63Author    R. K. Broszkiewicz+, T. Söylemez, D. Schulte-FrohlindeRequires cookie*
 Title    Reactions of OH Radicals with Acetylacetone in Aqueous Solution. A Pulse Radiolysis and Electron Spin Resonance Study  
 Abstract    Pulse radiolysis experiments monitoring optical absorbance as well as conductivity and in-situ ESR radiolysis studies show that the OH radical reacts with the enol (k = 8.6 x 10 9 M _1 s _1) and the enolate (k = 7.4 X 10 9 M _1 s -1) forms of acetylacetone by addition to the C = C double bond in aqueous N2O saturated solution. The OH reaction with enol leads to equal amounts of two radicals, CH3COCHOHCOHCH3 (2) and CH3COCHC(OH)2CH3 (4), as determined by scavenger reactions. At pH less than 1 the radical CH3COCHCOCH3 (1) is observed by ESR spectroscopy showing that radical 2 and/or 4 eliminate water by proton catalyzed reactions. Under alkaline condition the OH adducts to the enolate eliminate OH -with rate constants larger than 10 5 s -1 leading to radical 1. G(OH") is determined to be 5.6 showing that addition is the main reaction of OH with enolate. To a much smaller degree the OH radical is proposed to abstract an H atom from that CH3 group which is attached to the C —C double bond in enol and enolate, producing substituted allyl radicals which absorb in the visible region. The reaction of OH with the keto form has not been observed indicating that the rate constant of this reaction is significantly smaller than those with enol and enolate. 
  Reference    Z. Naturforsch. 37b, 368—375 (1982); received August 19 1981 
  Published    1982 
  Keywords    Pulse Radiolysis, OH Radicals, Acetylacetone, Reaction Mechanisms 
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 Identifier    ZNB-1982-37b-0368 
 Volume    37 
64Author    Peter Seidel, Ivar UgiRequires cookie*
 Title    Die Photoaddition von Bromtrichlormethan an Allyl-Systeme Photoaddition of Bromotrichloromethane to Allylic Systems  
 Abstract    Photoaddition of Bromotrichloromethane, 1-Substituted 4,4,4-Trichloro-2-bromobutanes The preparation of various 1-substituted 4,4,4-Trichloro-2-bromo-butanes by photo-addition of bromotrichloromethane to allylic systems is described. Generally a more uniform product and a higher yield are obtained by this photoaddition than by the corresponding chemically initiated radical chain reaction. 
  Reference    Z. Naturforsch. 37b, 376—379 (1982); eingegangen am 23. Oktober 1981 
  Published    1982 
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 Identifier    ZNB-1982-37b-0376 
 Volume    37 
65Author    G. N. Schrauzer, LauraA. Hughes, Norman StrampachRequires cookie*
 Title    The Chemical Evolution of a Nitrogenase Model, 20 Alkyl Molybdates(VI) and the Mechanism of Hydrocarbon Production by Nitrogenase [1]  
 Abstract    Nitrogenase Model, Alkyl Molybdates Colorless alkylmolybdates(VI) of composition R-M0O3-are generated in aqueous solutions by the alkaline hydrolysis of complexes R-Mo(Bpy)(0)aBr (Bpy = 2,2'-bipyridyl, R = CH3 and higher alkyl). At room temperature in alkaline aqueous solution, the new organometallic derivatives of oxomolybdate(VI) are remarkably resistant against Mo-C bond hydrolysis. Decomposition occurs more rapidly on heating, affording unrearranged alkanes according to the eq.: R-M0O3-+ OH -RH + Mo04=. In acidic solutions, the methylmolybdate(VI) species decomposes with the formation of a mixture of methane and ethane while higher alkylmolybdates carrying hydrogen in the /^-position relative to molybdenum undergo Mo-C bond heterolysis by way of ^-elimina-tion: R-CH2CH2-M0O3--* • Mo +4 (aq) + H+ + R-CH = CH2. The Mo-C bond of alkylmolybdates is resistant to oxidants but is very sensitive to cleavage under reducing conditions. Reductive Mo-C bond cleavage occurs particularly rapidly in the presence of thiols and reduced ferredoxin model compounds. The latter reactions simulate the terminal steps of hydrocarbon producing reactions of nitrogenase with alternate substrates such as CN -, R-CN or R-NC, confirming previous mechanistic conclusions concerning the mechanism of nitrogenase action. 
  Reference    Z. Naturforsch. 37b, 380—385 (1982); received September 1 1981 
  Published    1982 
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 Identifier    ZNB-1982-37b-0380 
 Volume    37 
66Author    G. J. Bukovits, H. BudzikiewiczRequires cookie*
 Title    Does a quasi-Thermal retro-Diels-Alder Decomposition Exist in Mass Spectrometry ? [1]  
 Abstract    retro-Diels-Alder Decomposition, Mass Spectra, 5 ^-Steroids Evidence is produced to the effect that in mass spectrometry a quasi-thermal retro-Diels-Alder decomposition does not occur. This reaction has to be triggered by the positive charge in the molecule. 
  Reference    Z. Naturforsch. 37b, 386—389 (1982); received September 7 1981 
  Published    1982 
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 Identifier    ZNB-1982-37b-0386 
 Volume    37 
67Author    M. Schulte-Kellinghaus, V. KrämerRequires cookie*
 Title    Preparation and Crystal Data of the Isotypic Aluminium (Gallium) Indium Sulphides AI2I114S9 and Ga2ln4S9  
 Abstract    The title compounds were prepared by chemi-cal vapour transport. They crystallize in the space group P 3m 1 with the lattice parameters a = 7.532(3) (7.589(5)) and c = 36.54(2) (36.70(5))!. X-ray powder diffraction data are listed and the T,x phase diagram of the system AlInS3-In2S3 is shown. 
  Reference    Z. Naturforsch. 37b, 390—391 (1982); eingegangen am 28. Oktober 1981 
  Published    1982 
  Keywords    Aluminium Indium Sulphide, Gallium Indium Sulphide, Crystal Data 
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 Identifier    ZNB-1982-37b-0390_n 
 Volume    37 
68Author    WilhelmF. Maier, Irina Thies, Paul Von, Ragué SchleyerRequires cookie*
 Title    Heterogeneous Catalysis, VI Direct Reduction of Alcohols to Hydro- carbons [1]  
 Abstract    Secondary and tertiary alcohols are converted cleanly to the parent hydrocarbons in the gas phase with H2 in the presence of a Ni/Al203 catalyst at 190 °C. Primary alcohols are de-hydroxymethylated; e.g., 1-hydroxymethylada-mantane (4) gives adamantane (1). Alumina alone, in the absence of Ni, results in the forma-tion of homoadamantane (5) from 4. 
  Reference    Z. Naturforsch. 37b, 392—394 (1982); received August 13 1981 
  Published    1982 
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 Identifier    ZNB-1982-37b-0392 
 Volume    37 
69Author    HansJoachim Breunig, Tevfik SeverengizRequires cookie*
 Title    Reduktion von Butyl-und Phenylantimon(III)bromiden sowie von t-Butylantimon(III)chloriden mit Magnesium in Gegenwart von Trimethylchlorsilan: Konkurrenz von Sb-Sb-und Sb-Si-Verknüpfung Reduction of Butyl-and Phenylantimony(III) Bromides and of £-Butylantimony(III) Chlorides with Magnesium in the Presence of Trimethylchlorosilane: Competition of Sb-Sb and Sb-Si Coupling  
 Abstract    Diphenyl(trimethylsilyl(stibine, Phenylbis(trimethylsilyl)stibine, Di-£er^butyl(trimethylsilyl)stibine, <er<-Butyl-bia(trimethylsilyl)stibine Butylantimony(III) bromides react with Mg in tetrahydrofuran (THF) even in presence of Me3SiCl exclusively with Sb-Sb-coupling: Starting from Bu2SbBr, Bu2SbSbBu2 is formed and BuSbBr2 is reduced to (BuSb)^. Sb-Si-coupling dominates in the reactions of PhaSbBr or *-Bu2SbCl with Mg/Me3SiCl/THF yielding Ph2SbSiMe3 or <-Bu2SbSiMe3. Both Sb-Sb-and Sb-Si-coupling reactions are observed, when PhSbBr2 reacts with Mg and Me3SiCl yielding PhSb(SiMe 3)2 and (PhSb)x. The same reactants can also form the distibanes Ph2(SiMe3)2Sb2 and Ph(SiMe3)3Sb2. The reaction of *-BuSbCl2 with Mg/Me3SiCl yields the stibines f-BuSb(SiMe 3)2 and Sb(SiMe3)3 together with (f-BuSb)i. In the reactions of«-BuSbCl2 or PhSbBr2 the ratio of Sb-Sb-and Sb-Si-coupling can be strongly influenced by using different reaction conditions. 
  Reference    Z. Naturforsch. 37b, 395—400 (1982); eingegangen am 11. Dezember 1981 
  Published    1982 
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 Identifier    ZNB-1982-37b-0395 
 Volume    37 
70Author    Cornelia Lensch, Oskar GlemserRequires cookie*
 Title    Darstellung und Reaktionen von S.N-Bi8(heptafluorisopropyl)schwefelfluoridimid Preparation and Reactions of S,N-Bis(heptafluoroisopropyl)sulphurfluoride Imide  
  Reference    Z. Naturforsch. 37b, 401—403 (1982); eingegangen am 8. Dezember 1981 
  Published    1982 
  Keywords    Sulphur-amide, N-hexafluoroisopropyl, S -[2 -chlorine-1, 1, 1, 3, 3, 3 -hexafluoro]isopropyl, Sulphurfluoride-imide, N-heptafluoroisopropyl, S-[2-chlorine-l, l, l, 3, 3, 3-hexafluoro]isopropyl, Sulphur-imide, N-heptafluoroisopropyl, S-dimethoxy 
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 TEI-XML for    default:Reihe_B/37/ZNB-1982-37b-0401.pdf 
 Identifier    ZNB-1982-37b-0401 
 Volume    37 
71Author    Henri Brunner, MonikaE. Dylla, GabrieleA M Hecht, Willigis PieronczykRequires cookie*
 Title    Synthese von ß-Diphenylphosphin-carbonyl-Verbindungen durch Umsetzung von Brommethyl-earbonyl-Verbindungen mit Diphenyl(trimethylsilyl)phosphin Synthesis of /9-Diphenylphosphine-carbonyl Compounds by Reaction of Bromomethyl-carbonyl Compounds with Diphenyl(trimethylsilyl)phosphine  
  Reference    Z. Naturforsch. 37b, 404—406 (1982); eingegangen am 13. November 1981 
  Published    1982 
  Keywords    /3-Keto-phosphines, Amino-phosphines, Imino-phosphines, Synthesis, NMR Spectra, Optical Activity 
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 Identifier    ZNB-1982-37b-0404 
 Volume    37 
72Author    Ekkehard Lindner, Michael SteinRequires cookie*
 Title    Darstellung, Eigenschaften und Reaktivität von 2-, 3-und 4-Chloracyl(diphenyl)phosphanoxiden Preparation, Properties and Reactivity of 2-, 3-and 4-Chloroacyl(diphenyl)phosphane Oxides  
  Reference    Z. Naturforsch. 37b, 407—411 (1982); eingegangen am 26. November 1981 
  Published    1982 
  Keywords    Chloroacyl(diphenyl)phosphanes, Diphosphorylated Alcohols, MS, IR Spectra, NMR Spectra 
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 Identifier    ZNB-1982-37b-0407 
 Volume    37 
73Author    Bernd WrackmeyerRequires cookie*
 Title    U B-und 18 C-NMR-Spektroskopie von riic7o-Hexaalkyl-2.3.4.5-tetracarbahexaboranen(6) n B and 13 C NMR Spectroscopy of 7iüZo-Hexaalkyl-2,3,4,5-tetracarbahexaboranes(6)  
  Reference    Z. Naturforsch. 37b, 412—419 (1982); eingegangen am 26. Oktober 1981 
  Published    1982 
  Keywords    U B NMR Spectra, 13 C NMR Spectra, nido -Hexaalky 1 -2, 3, 4, 5-tetracarbahexaboranes( 6) 
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 Identifier    ZNB-1982-37b-0412 
 Volume    37 
74Author    Martin Pfisterer, Günter NagorsenRequires cookie*
 Title    Darstellung, Struktur und elektrische Eigenschaften der Phase CaCu4As2 Preparation, Crystal Structure and Electrical Conductivity of CaCu4As2  
 Abstract    Investigations in the system Ca-Cu-As resulted in the discovery of CaCuiAs2. The phase crystallizes in a rhombohedral structure (Trigonal axes: a = 417.3(6) pm, c = 2262(3) pm, space group R~3m). The conductivity varies from 47 to 89 (i2cm) -1 having a minimum at 250 K. 
  Reference    Z. Naturforsch. 37b, 420—422 (1982); eingegangen am 27. Oktober 1981 
  Published    1982 
  Keywords    Calcium, Copper, Arsenide, Ternary Compound 
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 Identifier    ZNB-1982-37b-0420 
 Volume    37 
75Author    William Clegg, Uwe Klingebiel, GeorgeM. SheldrickRequires cookie*
 Title    Cyclisierungsreaktionen lithiierter Fluorsilanole und Aminofluorsiloxane - Kreuzdimerisierung eines Silicenium-Ylids Cyclisation Reactions of Lithiated Fluorosilanols and Aminofluorosiloxanes - Cross-dimerisation of a Silicenium-Ylid  
 Abstract    KOH reacts with bis(isopropyl-trimethylsilyl)-amino-difluorosilane to give the fluoro-silanol 1. An aminofluorosiloxane 2 is obtained in the reaction of [(Me3Si)2N]2SiF2 with KOH via a 1,3-silyl-group migration. The four-membered SiOSiN ring 5 can be prepared in several steps from 1. Six-membered SiO rings 8-10 are formed in the reaction of 1,3-fluorosilanols 6 and 7 with butyllithium. Lithiated 2 reacts with PCI3 to give a four-membered P2N2 ring 11, and with 2-methyl-2-propenal to give two isomeric (2 + 4) cycloadducts 12 and 13. The silicenium ylid formed initially by thermal elimation of LiF from lithiated 2 in PE/THF cross-dimerises to give a Si2N2 ring 14. If the reaction is carried out in n-heptane, the product after recrystallisation from acetone, 16, is an isomer of 14. The crystal structures of 14 and 16 have been determined. 
  Reference    Z. Naturforsch. 37b, 423—431 (1982); eingegangen am 14. Dezember 1981 
  Published    1982 
  Keywords    Fluorosüanols, Aminofluorosiloxanes, Cyclisation, Cross-dimerisation, Crystal Structure 
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 Identifier    ZNB-1982-37b-0423 
 Volume    37 
76Author    Requires cookie*
 Title    {©-«OH  
 Abstract    , 3 6 1 und 2 können formal auch als "Mischpolymere" aus Polythiazyl ((SN)Z) und Poly-p-phenylen ((CelLOz) bzw. Poly-p-phenylensulfid ((CÖHIS)*) an-gesehen werden. Für diese Substanzen sowie für 3-7 bot sich als universeller und schonender Syn-theseweg [6] die auch in der niedermolekularen S-N-Chemie besonders erfolgreiche Umsetzung von S-Cl-Verbindungen mit N-silylierten Diaminen und Diiminen an (Gin. (l)-(9)). * Sonderdruckanforderungen an Prof. Dr. O. J. Sche-rer. 0340-5087/82/0400-0432/$ 01.00/0 
  Reference    Z. Naturforsch. 37b, 432 (1982) 
  Published    1982 
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 Identifier    ZNB-1982-37b-0432 
 Volume    37 
77Author    K. Dietz, H. Endres, H. J. Keller, W. Moroni, D. WeheRequires cookie*
 Title    The Structure of 5,10-Dihydro-5,10-diethylphenaziniumyl (E2P+)-2,2'-(2,5-cyclohexadiene-l,4-diyIidene)-bispropanedinitrilate(TCNQ) and its Difference to the Phenazine Doped Species E2P-P-(TCNQ)2 (P = Phenazine)  
 Abstract    Phenazine free E2P-TCNQ, C28H22N6, Mr = 442.53 is monoclinic, P2i/c, a = 10.875(3), b = 14.679(4), c = 14.526(2) A, ß = 90.90(2)°, V = 2321.9 A 3 , Z = 4, dc = 1.27 Mgm~ 3 , the compound doped with 50% phenazine, E2P-P-(TCNQ)2 C52H34Nj2, Mr = 826.93, is tri-clinic, PT, o = 7.739(3), 6= 15.899(6), c = 17.037(7) A, a = 83.44(3), ß = 88.34(3), y = 83.19(3)°, V = 2067.7 A, Z = 2, dc= 1.33 Mgm-3 . E2P-TCNQ was refined to R = 0.066 for 1880 reflections. It consists of planar TCNQ anions and bent E2P cations (dihedral angle 17.7° along the line N-N) arranged in regular mixed stacks along c. The structure of E2P-P-(TCNQ)2 could be solved principally, but did not refine well (R = 0.165 for 1206 reflections). Regular segregated stacks of the phenazine and the TCNQ moieties are formed, and along the cationic stack the E2P+ cations and the neutral phenazine molecules alternate. 
  Reference    Z. Naturforsch. 37b, 437—442 (1982); received October 14 1981 
  Published    1982 
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 Identifier    ZNB-1982-37b-0437 
 Volume    37 
78Author    R. Tacke, A. Bentlage, W. S. Sheldrick, L. Ernst, K. StoepelRequires cookie*
 Title    Sila-Pharmaka, 24. Mitt. [1] Sila-Analoga von Nifedipin-ähnlichen 4-Aryl-2.6-cümethyl-1.4-dihydropyridin- 3.5-dicarbonsäure-dialkylestern, II Sila-Drugs, 24 th Communication [1] Sila-Analogues of Nifedipine-Like Di alkyl 4-Aryl-2,6-dimethyl-l,4-dihydropyridine- 3,5-dicarboxylates, II  
 Abstract    In the course of systematic studies on sila-substituted drugs the nifedipine-like 1.4-di-hydropyridine derivatives 4 a, 4 b and 4 c were prepared and investigated with respect to sila-substitution effects. By X-ray diffraction analyses 4 a, 4 b and 4 c were found to be isostructural. The C/Si-analogues exhibit similar spasmolytic activities (in vitro, guinea pig ileum), comparable with that of nifedipine. However, the compounds differ sub-stantially in their in vivo activity, as measured by the antihypertensive effect on the renal-hypertensive rat. The experimental results are discussed with respect to the carbon/silicon exchange. 
  Reference    Z. Naturforsch. 37b, 443—450 (1982); eingegangen am 25. September 1981 
  Published    1982 
  Keywords    Sila-Analogues of Nifedipine Derivatives, X-ray, Pharmacological Activity, Structure-Activity Relationships 
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 Identifier    ZNB-1982-37b-0443 
 Volume    37 
79Author    Hans Moser, Grety Rihs, Hanspeter Sauter, Entwicklung Forschung, PflanzenschutzRequires cookie*
 Title    Der Einfluß yon Atropisomerie und chiralem Zentrum auf die biologische Aktivität des Metolachlor The Influence of Atropisomerism and Chiral Centre on the Biological Activity of Metolachlor  
 Abstract    The four stereoisomers of the grass herbicide Metolachlor, the isomerism of which is based on a combination of a chiral centre and a chiral axis, were prepared, and their absolute configurations determined by X-ray analysis. The synthesis was achieved by using optically active starting materials and new optically active carbamates as intermediates. The herbicidal activity is mainly influenced by the chiral centre, the S-isomers being the most active ones. 
  Reference    Z. Naturforsch. 37b, 451—462 (1982); eingegangen am 20. August 1981 
  Published    1982 
  Keywords    Chloro-acetanilide, Metolachlor, Atropisomerism, Chiral Centre, Biological Activity 
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 Identifier    ZNB-1982-37b-0451 
 Volume    37 
80Author    A. Albini, H. Kisch, C. Krüger, An-Pei Chiang+Requires cookie*
 Title    Transition Metal Complexes of Diazenes, XVII [1] Reactions of 1,2-Diazetines and 1,2-Diazetine-N-oxides with Iron Carbonyls  
 Abstract    I,2-Diazetines, 1,2-Diazetine-N-oxide, Iron Complexes, X-ray Enneacarbonyldiiron reacts with 3,3,4,4-tetramethyl-l,2-diazetine (L) or its mono-N-oxide (L') to form complexes (L)Fe(CO)4 (3), (L)Fe2(CO)7 (4), (L)Fe2(CO)6 (5), or (L')Fe(CO)4 (6), and small amounts of deoxygenated 4 and 5, respectively. Formation and stability of the complexes is compared with those of ligands with smaller and larger ring sizes and discussed in terms of the electronic properties of the ligand lone-pair Orbitals. The molecular structure of 4 is established by X-ray analysis. 
  Reference    Z. Naturforsch. 37b, 463—467 (1982); received November 13 1981 
  Published    1982 
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 Identifier    ZNB-1982-37b-0463 
 Volume    37 
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