Single Crystal Study of the 19F Shielding Tensors of a Trifluoromethyl Group

Abstract

Coherent averaging techniques are used to examine the ¹⁹F shielding tensors of the trifluoromethyl group in single crystals of silver trifluoroacetate. At room temperature, where the CF₃ groups are rotating rapidly, the spectrum consists of a single line whose orientation dependence allows a determination of the orientation of the CF₃ groups in the unit cell. The rigid lattice (40°K) spectra exhibit the six lines expected on the basis of the x‐ray crystal structure, also determined in this work, and allow a determination of all six independent elements of each of the three incongruent chemical shift tensors.