Measurement of spin coupling constants to quadrupolar nuclei via relaxation studies

Arsenic and antimony hexafluoride salts have played an important role in the history of both solution and solid-state NMR spectroscopy. Here, solid polycrystalline KAsF6 and KSbF6 have been studied...

Assessing distortion of the AF 6 (A=As, Sb) octahedra in solid hexafluorometallates(V) via NMR spectroscopy

The polarized Raman spectra of single crystals of KSbF6-I of P42m-D symmetry are reported. The predicted LO-TO splittings of the B2 and E modes were not observed and the vibrational spectra do not indicate a non-centrosymmetric structure. The calculated relative intensities of the Raman bands in the single-crystal spectra agree very well with the observed values. It is shown that the anions execute fourfold reorientational motions around the S4 axis of the crystals and an activation energy of 3.2 kcal mol−1 (13.4 kJ mol−1) is calculated from the variation of the linewidths of Raman bands with temperature. The barrier is penetrated by the anions and because of the jumping motions of the anions in KSbF6-I the small distortions from a centrosymmetric structure are averaged out and the Raman and infrared spectra appear to be mutually exclusive.

KSbF6 revisited. I—A Raman and infrared study of the tetragonal phase I

The authors focus on the study of the physical properties of the low-temperature cubic phase f of KSbF/sub 6/. We give a change in the temperature dependences of the quadrupole coupling constants at the /sup 121/Sb nuclei, the spin-lattice relaxation time T/sub 1/ for the /sup 19/F nuclei, and the dielectric constant epsilon(T) in polycrystalline samples of KSbF/sub 6/. The NMR spectra of the /sup 121/Sb nuclei were recorded using a CW spectrometer at a frequency of 20 MHz. The T/sub 1/ measurements at the /sup 19/F nuclei were made using the IS-3 pulse spectrometer at a frequency of 27.2 MHz.

A.M. Heyns

Papers

A Raman and NMR study of KSbF6