Fluorination of osmium and ruthenium oxides: characterization and crystal structure of osmium dioxide tetrafluoride, OsO 2F 4

Abstract

Current results obtained on the fluorination of ruthenium and osmium oxides by strong fluorinating agents are presented. The product of the reaction of KrF 2 with OsO 4 in HF solution has been further characterized by 19F NMR spectroscopy and single crystal X-ray diffraction data. According to these results, the compound obtained is osmium dioxide tetrafluoride OsO 2F 4. The origin of the incorrect formulation (OsOF 6) previously given to this compound is discussed. The 19F NMR spectra indicate that there are two distinct pairs of equivalent fluorine atoms in the molecule. The X-ray diffraction data reveal a distorted octahedron of light atoms around the osmium atom, but as yet oxygen and fluorine are not distinguishable. Both methods combine clearly to indicate a distorted cis-octahedral structure. The cis-orientation of oxygen atoms is not in accord with the electron pair repulsion model; the distortions, however, can be interpreted in this manner.