Temperature dependence of the (1)J((11)B(19)F) spin-spin coupling in BF(3) molecule.

The (1)J((11)B(19)F) spin-spin coupling of gaseous BF(3) was observed in (11)B NMR spectra as a function of density in a wide range of temperatures. Following the extrapolation of the measured values to the zero-density limit, the coupling constant free from intermolecular effects (1)J(0)((11)B(19)F) was obtained for each temperature. In contrast to previous investigations, the final results indicate a nonlinear dependence of (1)J(0)((11)B(19)F) on temperature.

NMR shielding constants in BF(3) and magnetic dipole moments of (11)B and (10)B nuclei.

Gas-phase NMR spectra of (11)B, (10)B, and (19)F in BF(3) are reported, and high-level ab initio calculations of the corresponding NMR shielding constants are described. Extrapolation of the measured resonance frequencies to the zero-density limit ensures that the results correspond to the ab initio values for an isolated molecule. Simultaneous measurements of (3)He resonance frequencies and application of the calculated shielding constants allow us to determine improved values of the nuclear magnetic dipole moments of (11)B and (10)B.