11B Chemical Shifts of Three Coordinate Boron
The 11 B chemical shifts (δ11 B) for tervalent boron compounds depend upon the π-donor ability of the ligands. Therefore it is possible to observe δ11 B at rather high field although a low field resonance is expected on electronegativity grounds. Thus σ- and π-bonding effects have to be considered in discussing δ11 B data. The two effects are not easily separated because there are practically no compounds BX3 where X is a strong electronegative atom or group without free electron pairs available for π-bonding.
KeywordsRing System Boron Atom Upfield Shift Field Shift Steric Crowding
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