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  • 1
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: 31P and 195Pt N.M.R. Investigations on Diplatinum (I) Complexes of the Type [Pt2(μ-SPR2)2L2] (L = PR3, PhP(OPh)2, P(OPh)3, CNR)31P-, 195Pt-chemical shifts and 195Pt-31P- resp. 31P-31P-coupling constants of a series of doubly bridged diplatinum(I) complexes are reported. 31P-coordination chemical shifts of the terminal ligands of complexes of type [Pt2(μ-SPR2)2(P′R3′)2] and some of the various coupling constants are strongly influenced by the π-acceptor strength of these ligands. J(195Pt-195Pt) is found to change the sign among the series of complexes investigated. Thermal singlett triplet exitation giving rise to the paramagnetism of these complexes observed by preliminary EPR-measurements and confirmed by EHT-calculations is deduced from the large values of 2J(P-P′) and 3J(P′P′) as well as the unusually high temperature dependence of some coupling constants and other NMR features. The chemical stability of the doubly bridged core, the coordination shifts of the bridging phosphorus atoms and EHT-calculations suggest a view of aromaticity of the [Pt2(μ-SPR2)2](M-M) unit of these complexes.
    Notes: Es werden 31P-, 195Pt-chemische Verschiebungen und 195Pt31P-Kopplungskonstanten einer Reihe von doppelt verbrückten Diplatin(I)-Komplexen mitgeteilt. 31P-koordinationschemische Verschiebungen der ternären Liganden von Komplexen des Typs [Pt2(μ-SPR2)2(P′R3′)2] und verschiedene Kopplungskonstanten werden stark von der π-Akzeptor-Stärke dieser Liganden beeinflußt. J(195P-195Pt) wird innerhalb der Reihe der untersuchten Komplexe mit wechselndem Vorzeichen gefunden. Aus den großen Werten von 2J(Pt-P′) und 3J(P′P′) sowie der ungewöhnlich starken Temperaturabhängigkeit einiger Kopplungskonstanten und anderen NMR-Eigenschaften wird auf Paramagnetismus dieser Komplexe aufgrund thermischer Singlett-Triplett-Anregung geschlossen, der in vorläufigen EPR-Messungen gefunden und durch EHT-Rechnungen gestützt wird. Die chemische Stabilität des doppelt verbrückten Kerns, die koordinationschemischen Verschiebungen der Brückenphosphoratome und EHT-Rechnungen weisen auf Aromatizität der [Pt2(μ-SPR2)2](M-M)-Einheit dieser Komplexe hin.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 19 (1983), S. 725-737 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: We have assessed the accuracy of a commercially available computer software package for finite element method calculations of magnetostatic fields. The computer program, MSC/NASTRAN,Available from the MacNeal-Schwendler Corporation, Los Angeles, CA 90041, U.S.A. is well known for its wide applicability in structural analysis and heat transfer problems. We exploit the fact that the differential equations of magnetostatics are identical to those for heat transfer if the magnetic field problem is formulated with the reduced scalar potential.1 Consequently, the powerful, optimized numerical routines of NASTRAN can immediately be applied to two- and three-dimensional linear magneto-statics problems. Application of the NASTRAN reduced scalar potential approach to a ‘worst case’ two-dimensional problem for which an analytic solution is available has yielded much better accuracy than was recently reported2 for a reduced scalar potential calculation using a different finite element program. Furthermore, our method exhibits completely satisfactory performance with regard to computational expense and accuracy for a linear electromagnet with an air gap. Our analysis opens the way for large three-dimensional magnetostatics calculations at far greater economy than is possible with the more commonly used vector potential and boundary integral methods.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Contributions to the Chemistry of Halosilane Adducts. XVI. Synthesis, Properties, Crystal and Molecular Structure of Hexa(N,N-dimethylformamide)silicon(IV)-tetraiodideWhen SiI4 is reacted with DMF ionization of all SiI bonds occurs to give (2) (reaction of pure components) or (1) (CHCl3 solution). IR and 1H-NMR spectra are in accordance with the formation of the octahedral cation [Si · 6 DMF]4+, DMF being coordinated through the CO group. 1 is only slowly attacted by methanol or water DMF being liberated. 1 crystallizes in the monoclinic space group C2/c with 4 formula units per unit cell. The cation [Si · 6 DMF]4+ has 1 symmetry. DMF is coordinated to Si in trans-configuration with respect to NMe2 with donation by oxygen. SiO bond distances (175.4-177.2 pm) correspond to those of [Si(O2C6H4)3]2- and [Si(acac)3]+; an increase of the CO distances (126.1-128.9 pm) and decrease of the CN distances (126.4-129.1 pm) as compared to free DMF is observed. These changes and structural data are discussed.
    Notes: SiI4 reagiert mit DMF unter Ionisierung der SiI-Bindungen zu [Si · 6 DMF]I4 · 3 DMF (2) (ohne Lösungsmittel) bzw. [Si · 6 DMF]I4 (1) (in CHCl3). IR- und 1HNMR-Spektren sind in Übereinstimmung mit dem Vorliegen des oktaedrischen Kations [Si · 6DMF]4+ mit einer Koordination von DMF über die CO-Gruppe. Die Verbindung wird in Methanol oder Wasser nur langsam unter Freisetzung von DMF abgebaut. 1 kristallisiert monoklin in der Raumgruppe C2/c mit 4 Formeleinheiten pro Elementarzelle. Das oktaedrische Kation [Si · 6 DMF]4+ besitzt 1 Symmetrie. DMF ist über Sauerstoff an Si in trans-Konfiguration bezüglich der NMe2-Gruppe koordiniert. Die SiO-Abstände (175,4-177,2 pm) entsprechen denen von [Si(O2C6H4)3]2- und [Si(acac)3]+; die CO-Abstände sind länger (126,1-128,9 pm), die CN-Abstände sind kürzer (126,4 bis 129,1 pm) als im freien DMF. Diese Änderungen und Strukturdaten werden diskutiert.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Secondary Phosphine Chalcogenides. VII. Synthesis of Bis(tert.-butylphosphino)thane, ButHPCH2CH2PHBut, and 1-tert.-Butylphosphino-2-diphenylphosphinoethane, Ph2PCH2CH2PHBut, as well as their Secondary Phosphine ChalcogenidesThe reaction of Cl2PCH2CH2PCl2 with ButMgCl gives ButClPCH2CH2PClBut which is either hydrolysed to yield ButH(O)PCH2CH2P(O)HBut or reduced to give ButHPCH2CH2PHBut. This phosphine reacts with sulfur or selenium to give ButH(E)PCH2CH2P(E)HBut (E = S, Se).Treatment of Ph2PCH2CH2Cl with LiPHBut results Ph2PCH2CH2PHBut which is oxidized to give Ph2(E)PCH2CH2P(E)HBut (E = O, S, Se). The Ph2P group appears to be oxidized primarily. The compounds obtained are characterized by means of I.R. 1H and 31P-N.M.R. spectroscopy.
    Notes: Durch Reaktion von Cl2PCH2CH2PCl2 mit Bu1MgCl wird ButClPCH2CH2PClBut erhalten, das entweder zu ButH(O)PCH2CH2P(O)HBut hydrolysiert oder zu ButHPCH2CH2PHBut reduziert wird. Dieses PHosphin ergibt mit Schwefel bzw. Selen ButH(E)PCH2CH2P(E) HBut (E = S, Se).Ph2PCH2CH2Cl und LiPHBut setzen sich zu Ph2PCH2CH2PHBt um, das zu Ph2(E)PCH2CH2P(E)HBt (E = O, S, Se) oxidiert wird, wobei primär die PH2P-Gruppe reagiert. Die dargestellten Verbindungen werden mit Hilfe ihrer IR-, 1H- und 31P-Spektren charakterisiert.
    Additional Material: 1 Tab.
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 113 (1980), S. 70-78 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The Reaction of Dinitrogen with Benzyne in the Coordination Sphere of TitaniumThe formation of aniline from dinitrogen during the thermolysis of diphenyltitanocene (1) and in the system (C5H5)2TiCl2 (3) + Mg + o-bromofluorobenzene (4) + N2 has been found to proceed via N2 reaction with intermediate Ti-benzyne complex (2). This is indicated by the isomeric composition of toluidines obtained from N2 and ditolyltitanocenes, the formation of [2-D1]aniline in the system 3 + Mg + 4 + N2 on hydrolysis with D2O and by nitrogen isotope fractionations at natural 15N-abundance in the reaction products.
    Notes: Die Bildung von Anilin aus Stickstoff bei der Thermolyse von Diphenyltitanocen (1) und im Reaktionssystem (C5H5)2TiCl2 (3) + Mg + o-Bromfluorbenzol (4) + N2 verläuft über die Reaktion von N2 mit einem intermediären Titan-Dehydrobenzol-Komplex (2). Das ergibt sich aus der Isomerenverteilung von Toluidinen, die aus N2 und Ditolyltitanocenen erhalten wurden, aus der Bildung von [2-D1]Anilin bei Hydrolyse des Systems 3 + Mg + 4 + N2 mit D2O sowie aus Stickstoffisotopen-Fraktionierungen in den Reaktionsprodukten mit natürlicher 15N-Häufigkeit.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 1914-1922 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Structure of Spiro[1,3,2λ5-benzoxaza (diaza)phosphole-2,5′λ5-dibenzophospholes]o-Aminophenols or o-phenylenediamines react with 5,5-dibromodibenzophospholes to give spirophosphoranes 1-6. The 31P-, 13C- and 1H-NMR spectra are independent of temperature, therefore, no evidence of a permutation process was detectable. As an example the structure of the heterocyclic compound 4,6-di-tert-butyl-1-ethyl-1,3-dihydro-2-phenylspiro[2H-1,3,2λ5-benzodiazaphosphole-2,5′-λ5-dibenzophosphole] (5) was determined by X-ray crystallography. The compound crystallizes in the space group P212121 with Z=4. The five-membered rings are attached to the phosphorus in an equatorial-axial manner. The phenyl and the NH group occupy equatorial positions, the N-C2H5 substituent is axially located. According to the geometry determined an assignment of the NMR coupling constants was done. Spiro compounds 1-6 show a very similar geometry.
    Notes: o-Aminophenole oder o-Phenylendiamine reagieren mit 5,5-Dibromdibenzophospholen zu Spirophosphoranen 1-6. Die 31P-, 13C- und 1H-NMR-Spektren sind temperaturunabhängig, so daß keine Hinweise für eine Permutationsisomerisierung aufgefunden wurden. Die Struktur wurde am Beispiel des 4,6-Di-tert-butyl-1-ethyl-1,3-dihydro-2-phenylspiro[2H-1,3,2λ]5-benzodiazaphosphol-2,5′-λ5-dibenzophosphols (5) bestimmt. Die Verbindung kristallisiert in der Raumgruppe P212121 mit Z=4. Die Fünfringe sind äquatorial-axial an den Phosphor gebunden. Der Phenylrest und die NH-Gruppe besetzen äquatoriale Positionen, der N-C2H5-Substituent ist axial gebunden. Damit können die NMR-Kopplungen zugeordnet werden. Die Spiroverbindungen 1-6 besitzen eine vergleichbare Geometrie.
    Additional Material: 1 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 113 (1980), S. 3656-3661 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Condensed Furans, XLVII. Synthesis of 1H-Pyrano[3,4-b]benzofuran-1-one and their DerivativesThe synthesis of 1H-pyrano[3,4-b]benzofuran-1-one derivatives (6-14) and their 2-aza-analogues (15-16) is described.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 15 (1980), S. 935-942 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 17 (1981), S. 156-156 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 17 (1981), S. 335-346 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Splitting methods for time-dependent partial differential equations usually exhibit a drop in accuracy if boundary conditions become time-dependent. This phenomenon is investigated for a class of splitting methods for two-space dimensional parabolic partial differential equations. A boundary-value correction discussed in a paper by Fairweather and Mitchell for the Laplace equation with Dirichlet conditions, is generalized for a wide class of initial boundary-value problems. A numerical comparison is made for the ADI method of Peaceman-Rachford and the LOD method of Yanenko applied to problems with Dirichlet boundary conditions and non-Dirichlet boundary conditions.
    Additional Material: 6 Tab.
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