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  • 1
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 22 (1984), S. 90-92 
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Some shielding calculations, using Pople's SOS model, are reported for B, C, N, F, P and Si as a function of changes in bond length and pyramidal bond angle. In all cases considered, the shielding is predicted to decrease as the bond length increases, which is in line with the available experimental data. The observed temperature variation of the nitrogen and phosphorus shieldings of NH3, PH3 and PF3 could be accounted for by a decrease in the pyramidal angle at higher temperatures. A similar angular variation for NF3 is predicted to cause a shielding variation, with temperature, in the same sense as that reported for NH3 and PH3, but opposite to that for PF3.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 22 (1984), S. 209-214 
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 15N NMR chemical shift data are presented for 14 azolopyridines, together with the results of INDO/S-SOS calculations of nitrogen shieldings. Previous 14N NMR results for some of these compounds are reinterpreted. The 14N data and their assignments are shown to be reliable for the indolizine nitrogen atom from arguments based on relative line widths. The pyridine-type nitrogens are more reliably assigned from the 15N spectra combined with the results of the INDO/S-SOS calculations for individual molecules. A combination of 14N and 15N NMR spectra, together with the shielding calculations, provides a basis for unambiguous assignments of all the various nitrogen environments considered.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 23 (1985), S. 748-753 
    ISSN: 0749-1581
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Solvent effects on nitrogen shieldings are shown to vary from almost zero to about 26 ppm. These shielding variations can be analysed in terms of a variety of hydrogen bonding interactions and non-specific solute-solvent interactions. Steric effects are also taken into account. The non-specific interactions are found to be well accounted for by INDO/S-SOS shielding calculations incorporating the solvaton model. Nitrogen NMR is shown to be very suitable for distinguishing between a variety of solute-solvent interactions.
    Additional Material: 6 Tab.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 23 (1985), S. 166-169 
    ISSN: 0749-1581
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 15N NMR shielding measurements reveal that thiolo-imidazole and -tetrazole exist almost entirely as the thione form. Quantitative estimates of the position of tautomerism in 1,2,3-triazole and tetrazole are obtained. The reported assignments are supported by means of INDO/S-SOS shielding calculations.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
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