Unstable intermediates. Part 167. Electron spin resonance studies of trifluorosilyl and related radicals

Abstract

Exposure of SiF₄ to ⁶⁰Co γ-rays at 77 K gives a species (A) exhibiting strong hyperfine coupling to ²⁹Si and to three 19F nuclei, together with weak coupling to four other equivalent 19F nuclei. This species is tentatively identified as SiF₃˙ interacting weakly with a neighbouring SiF₄ molecule, but other possibilities are discussed, Species very similar to A, but with different sub-structures, are obtained from Si₂F₆ and SiF₃H, together with SiF₂H˙ in the latter case. Species A is not obtained from O(SiF₃)₂ or SiF₃(NMe₂), but species similar to A containing two strongly coupled ¹⁹F nuclei have been detected. These are identified as F₂SiOSiF₃ and SiF₂(NMe₂) respeclively. The radical O(SiF₃) is obtained in certain samples of SiF₄.