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Inclusion of hydrogen p orbitals in the semiempirical calculation of NMR parameters. III: INDO CHF calculations of orbital and dipolar contributions to spin–spin coupling constants involving protons

✍ Scribed by J. C. Facelli; R. H. Contreras

Publisher: John Wiley and Sons
Year: 1981
Tongue: English
Weight: 497 KB
Volume: 20
Category: Article
ISSN: 0020-7608
DOI: 10.1002/qua.560200414

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✦ Synopsis

Abstract

The self‐consistent perturbation theory is used to calculate noncontract contributions to spin–spin coupling constants involving protons. Molecular wave functions were obtained with a modified version of the INDO method which includes hydrogen 2__p__ orbitals in its basis set. It is found that in many cases the orbital and dipolar terms are by no means negligible, being particularly important in geminal HH couplings. Results reported in this paper for this type of coupling, reproduce experimental trends in the series CH~4~, NH~3~, and OH~2~. In general, noncontact terms are found to decrease as the number of bonds separating the interacting nuclei increases.

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Inclusion of hydrogen p orbitals in the

Inclusion of hydrogen p orbitals in the semiempirical calculation of NMR parameters. I. Influence on the FPT INDO spin–spin coupling constants

✍ J. C. Facell; R. H. Contreras 📂 Article 📅 1980 🏛 John Wiley and Sons 🌐 English ⚖ 494 KB

## Abstract Hydrogen 2__p__ orbitals have been introduced into the basis set to calculate the Fermi contact term of spin–spin coupling constants using the FPT INDO method. Different coupling constants show different sensitivity to these hydrogen polarization functions. Some improvements are found f