P. Love
Dec 1, 1963
Citations
0
Influential Citations
11
Citations
Journal
Journal of Chemical Physics
Abstract
The boron‐11 quadrupole coupling constants of the simple aliphatic symmetrical trialkylboranes determined at 77°K are primarily a function of the number of α‐carbon—hydrogen bonds in these compounds. The average value of e2Qqzz in triethyl, tri‐n‐propyl, and tri‐n‐butylborane is 125±4 kc/sec higher than that in trimethylborane. The quadrupole coupling constant in tri‐isopropylborane is increased an additional 249±4 kc/sec above the value in the α‐methylene compounds. The α‐secondary hydrogen isotope effect in trimethylborane is to increase e2Qqzz by 28±4 kc/sec. However, there is no β‐secondary hydrogen isotope effect in tri‐isopropylborane within the limits of experimental error. These results, the proton high resolution NMR spectra, and the available chemical measures of the Lewis acidity of these compounds, are in excellent agreement with classical carbon—hydrogen bond delocalization theory.