Boron, Nitrogen, and Fluorine Nuclear Quadrupole Coupling and the Electronic Structure of the Boron—Nitrogen Single Bond

Abstract

The 11B and 19F nuclear quadrupole couplings in F3BNHx(CH3)3-x compounds are reported. The boron quadrupole couplings were measured by quadrupole perturbed NMR in the solid state. The fluorine quadrupole couplings were obtained by the time-differential observation of the angular distribution of the gamma radiation after excitation of the fluorine nuclei with accelerated protons (TDPAD). The results are discussed in connection with the nitrogen quadrupole couplings in F3BNHxR3-x compounds, and the nitrogen and boron quadrupole couplings in H3BNHxR3-x: compounds which were previously determined by nuclear quadrupole double resonance. In the F3BNHxR3-x series of compounds, the donor-acceptor character of the B -N bond appears to be less im portant than in the H3BNHxR3-x compounds in favour of a more ionic character of the bond with a higher negative charge on nitrogen.