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Some CNDO/S parameterized calculations of intramolecular effects on nuclear shielding

✍ Scribed by B. T. Hamdi; D. J. Reynolds; G. A. Webb

Publisher: John Wiley and Sons
Year: 1984
Tongue: English
Weight: 299 KB
Volume: 22
Category: Article
ISSN: 0749-1581
DOI: 10.1002/mrc.1270220207

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✦ Synopsis

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 NF, is predicted to cause a shielding variation, with temperature, in the same sense as that reported for NH, and PH,, but opposite to that for PF,.

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