ESR study of F₃²⁻ in γ-irradiated KAsF₆

Abstract

An ESR study of single crystals of KAsF₆, γ irradiated and observed at 77°K, has been made. A three-fluorine center similar to the Vt center, F₃²⁻, has been identified, and the principal components and directions for the g tensor, and for the fluorine hyperfine interaction tensors, have been obtained. The center is nonlinear with bond angle F F F = 150°±3°, the odd-electron density being larger on the central fluorine atom and smaller on the two equivalent end fluorine atoms of the radical. INDO calculations suggest that it is a σ-type radical with the unpaired spin density distributed in the fluorine orbitals lying in the plane of the three atoms.