Nuclear Magnetic Resonance Studies of Boron Trifluoride and Some of its Complexes

Abstract

<p> Nuclear magnetic resonance spectroscopy has been used to study donor-acceptor complexes of boron trifluoride with ketones, water, and methanol. Various NMR techniques have been applied which, in certain favourable cases, have yielded information on the stoichiometry, structure, relative stabilities, and reactions of the complexes in solution. A new method is proposed for the detection of BF3 complexes having low formation constants.</p> <p> The magnitude and sign of the B-F coupling constant in the tetra-fluoroborate anion have been found to be dependent on the solvent. This solvent dependence is interpreted in terms of solvation and association of the ion in solution.</p> <p> 19F spectra of 10BF3 over a range of temperatures agree well with line shapes calculated, using Pople's expressions, for coupling of fluorine-19 with boron-10 (I=3) which is undergoing partial quadrupole relaxation.</p>