Magnetic resonance studies on osmium pentafluoride oxide

Abstract

Well resolved electron spin resonance spectra of OsOF₅ were obtained in WF₆, Freon 133a (CF₃CH₂Cl) and SO₂ at 77 K. Hyperfine coupling to ¹⁸⁹Os and to four equivalent fluorine atoms was measured, but no coupling to the axial fluorine was observed. From analysis of the spin-Hamiltonian parameters it was concluded that ca. 11.5% of the unpaired electron was delocalised from the osmium d_xy orbital on to each equatorial fluorine atom. The results were compared with newly calculated data for [MOF₅]^2–(M = Cr, Mo or W) and [ReOF₅]^–. The anisotropic parameter P for Os^VII was calculated to be 0.0326 cm^–1.