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Calculation of some boron nuclear screening constants

✍ Scribed by K. A. K. Ebraheem; G. A. Webb

Publisher
John Wiley and Sons
Year
1977
Tongue
English
Weight
263 KB
Volume
10
Category
Article
ISSN
0749-1581

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✦ Synopsis

Abstract

Boron screening constants and their anisotropies have been calculated for 23 trivalent boron compounds. The calculations have been performed within a framework in which gauge‐dependent atomic orbitals are used in the molecular orbital description. Reasonable agreement with experimental chemical shifts is found when CNDO/S parameters are used; INDO calculations are less satisfactory. No correlation is found between the observed chemical shifts and those estimated from the Average Excitation Energy approach. Similarly, no correlation is found with total boron charge densities although agreement is reported with Ο€ charge density. In trimethylboron the lowest energy Οƒβ†’Ο€* transition dominates the in‐plane contributions to the local paramagnetic term while various Οƒβ†’Ο€* transitions dominate the out‐of‐plane contributions.

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