NMR of HBF4

Abstract

Longitudinal and transverse relaxation times for all three species of nuclei in aqueous solutions of HBF₄ have been measured by pulse techniques. Relaxation measurements were performed at room temperature as a function of HBF₄ concentration. The relaxation times of each nuclear species exhibited a strong concentration dependence. In addition, cw measurements were performed in order to determine the nature of the electric and magnetic interactions. The results demonstrate that the ¹⁹F nuclei are participating in a chemical exchange process which produces a ¹¹B spin multiplet collapse. The concentration dependence of the ¹H nucleus was studied to determine the type of coupling that exists between the ¹H nuclei and their environment. On the basis of the transverse relaxation and cw measurements, a spin–lattice relaxation model was constructed for the HBF₄ system. Theoretical estimates of the relaxation parameters were made using the BPP model.