NMR of KBiF6 Powder: The Sign of Bi–F Spin—Spin Coupling and the Bi Quadrupole Coupling

An analysis of ¹⁹F NMR spectra of polycrystalline KBiF₆ is performed by matching computer generated spectra with the observed spectra. The complex patterns of the spectra arise from a scalar spin—spin coupling between the spin‐9/2 ²⁰⁹Bi which interacts with the electric field gradient via the quadrupole interaction and the spin‐1/2 ¹⁹F. The fits of the experimental spectra with the calculated spectra are good and yield the following parameters. The Bi—F spin—spin coupling is $\text{∓ 2.7±0.3\hspace{0.17em}}\mathrm{kHz}$ and the ²⁰⁹Bi quadrupole coupling e²qQ/h in KBiF₆ is $\text{±132±12}\mathrm{MHz}$ with the top signs favored from crystallographic and NMR considerations.