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  • 1
    Keywords: Medicine ; Spectroscopy ; Biotechnology ; Chemistry, Organic ; Chemistry, Physical organic ; Biochemistry ; Biomedicine ; Biomedicine general ; Spectroscopy/Spectrometry ; Biotechnology ; Physical Chemistry ; Organic Chemistry ; Biochemistry, general ; Springer eBooks
    Description / Table of Contents: The basis of Nuclear Magnetic Resonance Spectroscopy -- Spectroscopic parameters in Nuclear Magnetic Resonance -- Basic NMR experiments -- Biomolecular NMR
    Abstract: This book intends to be an easy and concise introduction to the field of nuclear magnetic resonance or NMR, which has revolutionized life sciences in the last twenty years. A significant part of the progress observed in scientific areas like Chemistry, Biology or Medicine can be ascribed to the development experienced by NMR in recent times. Many of the books currently available on NMR deal with the theoretical basis and some of its main applications, but they generally demand a strong background in Physics and Mathematics for a full understanding. This book is aimed to a wide scientific audience, trying to introduce NMR by making all possible effort to remove, without losing any formality and rigor, most of the theoretical jargon that is present in other NMR books. Furthermore, illustrations are provided that show all the basic concepts using a naive vector formalism, or using a simplified approach to the particular NMR-technique described. The intention has been to show simply the foundations and main concepts of NMR, rather than seeking thorough mathematical expressions
    Pages: XII, 115 p. 36 ill. : digital.
    ISBN: 9789400769762
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  • 2
    ISSN: 0947-6539
    Keywords: azadienes ; azepines ; cycloadditions ; Fischer carbenes complexes ; reaction mechanisms ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 4-Amino-1-azadienes 1 react with α,β-unsaturated Fischer carbene complexes at -40°C to give stereoselectively a variety of substituted 3H-4,5-dihydroazepines 3; similarly, 1-hydroxy-1-azadienes (α,β-unsaturated oximes) 6 afforded the corresponding azepine derivatives 7. Chiral, nonracemic carbene complexes 11 gave azepines 12-13 (d.e. = 40-44%) upon reaction with oxime 6a; the major isomers were obtained in a diastereomerically and enantiomerically pure form (45-50% overall yield) after crystallization. An X-ray structure of 12a allowed assignment of the absolute stereochemistry. The acid hydrolysis of azepines synthesized provided racemic and enantiomerically pure 1,6-dicarbonyl compounds (±)-5, (±)-9, and (-)-14, as well as diol (-)-15. The mechanism of the reaction of 1 and 2 was investigated by multinuclear (1H, 13C, 15N, and 183W) NMR characterization of four intermediates (A, B, C, and D) at low temperature. The experimental sequence of events involves: i) 1,2-nucleophilic addition of the unsubstituted imine nitrogen of 1 to the metal carbene function (zwitterion A, -60°C), ii) cyclization to the seven-membered ring with 1,2-migration of the pentacarbonyl metal (zwitterion B, -40°C), iii) reductive elimination and coordination of the metal to the amine nitrogen (intermediate C, -40°C), and iv) thermal decomplexation and tautomerization (intermediate D and compound 3, above -20°C).
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1434-1948
    Keywords: Cyclotriphosphazenes ; Oxypyridine ; Carbonyltungsten compounds ; NMR spectroscopy ; Heterocycles ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reactions of [N3P3(dobp)2Cl2] and [N3P3(dobp)Cl4] with a mixture of HOC5H4N-4 and K2CO3 in acetone give the cyclotriphosphazenes [N3P3(dobp)2(OC5H4N-4)2] and [N3P3(dobp)(OC5H4N-4)4], respectively. These compounds react with [W(MeOH)(CO)5] in methanol to give mixtures of the polymetallic complexes [N3P3(dobp)2(OC5H4N-4)2{W(CO)5}x] (x = 1, 2) and [N3P3(dobp)(OC5H4N-4)4{W(CO)5}x] (x = 1-4), which are unstable in solution, slowly undergoing loss of the pentacarbonyl moiety. A complete characterization by multinuclear 1H, 15N, 31P, 183W magnetic resonance has revealed that the complexation of the N atom of one 4-oxypyridine ligand by the W(CO)5 fragment has a measurable effect on other parts of the phosphazene molecule very far away from the coordination site. The changes observed in δ183W have been used to identify the components in mixtures of compounds incorporating different numbers of tungsten atoms in the molecule. The characterization of less sensitive nuclei has been accomplished by means of indirect detection methods.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1434-1948
    Keywords: Alkenylcarbynes ; Dinuclear tungsten complexes ; Electrochemistry ; Tungsten NMR ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Neutral trans-cyanide alkenylcarbyne complexes 2a and 2b have been prepared by reaction of the complex 1a and 1b with NaCN or [Bu4N]CN. The reaction of complexes 2a and 2b with an equimolar amount of the acetonitrile complexes 1a and 1b in CH2Cl2 leads to the cationic cyanide-bridged bis(alkenylcarbyne) di-tungsten complexes 3a-d. Diisocyanide-bridged bis(alkenylcarbyne) di-tungsten complexes 4a and 4b have been synthesized by the reaction of complexes 1a and 1b with 0.5 equivalents of the diisocyanide 1,4-(CN)2C6H4. IR as well as 1H-, 31P{1H}-, 13C{1H}-, and 183W-NMR data are reported. The spectroscopic data show that in the dinuclear complexes 3a-d, the bridging CN group and the alkenylcarbyne units are located in trans positions, while in the dinuclear complexes 4a and b, the isocyanide groups of the bridging ligand 1,4-(CN)2C6H4 and the two alkenylcarbyne moieties are cis. The 183W chemical shifts of complexes 2a, 2b, 3a-d, 4a, and 4b were obtained through two-dimensional indirect 31P, 183W NMR recording techniques. A downfield shifting of 183W resonances of the cyanide-bridged dinuclear complexes 3a-d with respect to the mononuclear ones, 2a and 2b, was observed. The δ183W of isocyanide bridging dinuclear complexes 4a and 4b appear at higher field than those of the corresponding mononuclear cyanide 2a and 2b in accordance with the higher π-acceptor electron properties of the isocyanide ligand. The electrochemical behaviour of all the complexes has been investigated by cyclic voltammetry and controlled potential electrolysis in aprotic media and at a Pt (or vitreous C) electrode. Complexes 1, 2, or 3 undergo multi-electron irreversible oxidation processes involving anodically induced proton dissociation from the alkenylcarbyne ligands, and irreversible cathodic processes are also observed for all the complexes. The order of the redox potentials reflects that of the net electron π-acceptor/σ-donor character of the ligands and the ligating alkenylcarbynes are shown to behave as remarkably strong π-electron acceptors (even stronger than CO).
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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