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  • Analytical Chemistry and Spectroscopy  (6)
  • 1
    Electronic Resource
    Electronic Resource
    Kernresonanzspektroskopische Untersuchungen an Pentafluorphenylsubstituierten Silanen: II-Fernkopplungen und Through Space Effekte (1974)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 6 (1974), S. 66-72 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Long range 5J(FH) and 6J(FH) couplings were observed for silanes of the type (C6F5)nSiR4-n (n = 1, 2, 3; R = alkyl, aryl) and disilanes C6F5[Si(CH3)2]2R (R = CH3, C6F5). A characteristic increase in line width for 19F-NMR spectra of (C6F5)nSiR4-n(n ≧ 2) is thought to be due to spin systems of the type ([AC]2B)n or ([AX]2M)n with intra-annular couplings between ortho-fluorine atoms of neighbouring ring systems.
    Notes: Longrange-Kopplungen des Typs 5J(FH) und 6J(FH) werden bei Silanen des Typs (C6F5)nSiR4-n (n = 1, 2, 3; R = Alkyl, Aryl) sowie den Disilanen C6F5[Si(CH3)2]2R (R = CH3, C6F5) beobachtet. Eine typische Linienverbreiterung der Fluor-resonanzspektren von (C6F5)nSiR4-n (n ≧ 2) wird auf Spinsysteme des Typs ([AC]2B)n bzw. ([AX]2M)n mit interanularen Kopplungen der ortho-Fluor-atome benachbarter Ringe zurückgeführt.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270060203
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  • 2
    Electronic Resource
    Electronic Resource
    Kernresonanzspektroskopische Untersuchungen an C6H2F2(SCH3)2-Isomeren: Das [AMX3]2 Spinsystem (1974)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 6 (1974), S. 374-379 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The isomeric compounds 1,2-difluoro-4,5-dimethylthiobenzene and 1,4-difluoro-2,3-dimethylthiobenzene were synthesised from CH3SNa and 1,2,4,5-tetrafluorobenzene and 1,2,3,4-tetrafluorobenzene, respectively. The structures of both the C6H2F2(SCH3)2 isomers were determined by NMR spectroscopic methods. The subspectral breakdown of an [AMX3]2 spin system is shown for the limiting case of vanishing long range coupling constants.
    Notes: Aus CH3SNa und 1,2,4,5- bzw. 1,2,3,4-Tetrafluorobenzol wurden 1,2-Difluor-4,5-dimethylthiobenzol bzw. 1,4-Difluor-2,3-dimethylthiobenzol dargestellt. Die Struktur der beiden C6H2F2(SCH3)2-Isomeren wurde durch kernresonanz-spektroskopische Methoden bestimmt. Der subspektrale breakdown des [AMX3]2-Spinsystems wird für den Sonderfall verschwindender long-range-Kopplungen abgeleitet.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270060704
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  • 3
    Electronic Resource
    Electronic Resource
    Kernresonanzspektroskopische Untersuchungen an cis-(CH3)2Pt[P(OCH3)3]2 (1977)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 9 (1977), S. 325-327 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: 100 MHz 1 H n.m.r. spectra of cis-(CH3)2Pt[P(OCH3)3]2 are analysed in full detail as superimposing [AR3X9]2 and [AR3X9]2M systems. The cis structure is derived from J(PP) and J(PtP).
    Notes: 100 MHz 1H NMR Spektren von cis- (CH3)2Pt[P(OCH3)3]2 werden als Superposition von [AR3X9]2-und [AR3X9]2M -Systemen analysiert. Die cis-Struktur wird abgeleitet von den Kopplungskonstanten J(PP) und J(PtP).
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270090608
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  • 4
    Electronic Resource
    Electronic Resource
    Solid-state NMR study of a series of aminophosphonic acids (1989)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 27 (1989), S. 470-475 
    Details
    ISSN: 0749-1581
    Keywords: Solid-state NMR ; Aminophosphonic acids ; Crystallography ; Shielding tensors ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: High-resolution 31P, 15N and 13C NMR spectra have been obtained for nine solid aminophosphonic acids under conditions of high-power decoupling, cross-polarization and magic-angle spinning. The NMR evidence shows that the asymmetric unit is a single molecule in all cases, which is consistent with the available diffraction studies. Phosphorus-31 shielding tensor components determined from static and slow-spinning MAS spectra are given for a number of the compounds.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260270509
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  • 5
    Electronic Resource
    Electronic Resource
    Monitoring site-specific natural hydrogen isotope fractionation using a novel phosphorus-containing chiral discriminating reagent (1991)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 29 (1991), S. 813-822 
    Details
    ISSN: 0749-1581
    Keywords: Ethanol ; Deuterium ; SNIF-NMR ; 1H NMR ; 13C NMR ; 31P NMR ; 2D NMR ; Chiral discrimination ; Aromatic ring current ; Molecular structure ; MOPAC ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of a novel chiral discriminating reagent, the ester resulting from the reaction of L-menthylphenylphosphoryl chloride with ethanol, is reported. This reagent, C, is aimed to differentiate the R and S monodeuterated enantiomers of ethanol, which constitutes an important isotopic probe for mechanistic studies and origin inference of natural products. The proportions of the two P-epimeric structures, CA and CB, which compose reagent C are directly accessible by 31P NMR. Analysis of 1D and 2D NMR spectra and theoretical simulations enable the 1H and 13C chemical shifts of CA and CB to be determined. The chemical shift differences exhibited by the methylenic hydrogens of the ethoxy moiety in CA and CB are of the order of 0.3 ppm. These large differences can be mainly attributed to ring current effects. Such effects have been estimated using two different methods on the basis of model conformations of the two epimers, CA and CB, deduced from energy minimization in a quantum mechanical approach. The relative signs of the chemical shift differences δR(C) - δS(C) associated with the pro-R and pro-S positions in the CA and CB isomers cannot be determined from the proton spectrum. The ring current calculations suggest that δR(C) - δS(C) are of opposite signs in the two P-epimers. This interpretation, and consequently the conformational analysis, are supported by the 2H NMR study of a chiral discriminating ester prepared from ethanol selectively enriched in deuterium in the pro-R position by stereospecific exchange reactions involving the enzymatic pair alcohol dehydrogenase-diaphorase. The chiral discriminating reagent, C, was then used for determining the enantiomeric imbalance in ethanol samples obtained from biosynthesis under different conditions, and site-specific fractionation factors were calculated.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260290812
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  • 6
    Electronic Resource
    Electronic Resource
    2-Dimethoxyphosphoryl-1,3-dithiane: A comparison of NMR studies for 1H, 13C and 31P nuclei by one- and two-dimensional NMR techniques (1985)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 23 (1985), S. 18-22 
    Details
    ISSN: 0749-1581
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2-Dimethoxyphosphoryl-1,3-dithiane was obtained by the reaction of 2-chloro-1,3-dithiane with trimethyl phosphite. Studies at 200, 360 and 400 MHz using 1H, 13C and 31P nuclei and 1D- and 2D NMR techniques are described. Long-range coupling constants were extracted by iterative treatment of [AB]2CDMR6X spin systems. A rigid dithiane structure with axial phosphorus is consistent with the NMR results. Analogous dithianes and solid-state structures are discussed.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260230108
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