Matrix-Isolation Study of the Vacuum-Ultraviolet Photolysis of Trifluorosilane. The Infrared Spectrum of the Free Radical SiF3

In studies of the vacuum-ultraviolet photolysis of SiHF3 suspended in argon, nitrogen, and carbon monoxide matrices at 14°K, evidence has been obtained indicating that H-atom detachment occurs and that the SiF3 free radical is stabilized. All of the vibrational fundamentals of SiF3 have been observed in these experiments. The appearance of two stretching fundamentals requires that the molecule be non-planar. A more detailed consideration of the pattern of vibrational absorptions indicates that the angle between each Si–F bond and the threefold symmetry axis of the molecule is approximately 71°, close to the value characteristic of sp3 hybridization of the valence electrons about the central atom. Force constants have been estimated using a four-constant valence-force potential, and the thermodynamic properties of SiF3 have been calculated.