A new method for preparing Os03Fz is presented. Its crystal structure reveals a polymeric chain structure with distorted octahedral geometry for the Os03F3 units and symmetrical, non-linear fluorine bridges. The Os0,F3 unit has a facial geometry. This structure is not in accord with predictions on the molecular structure of Os03F,. OsOzF,, obtained from KrFz and Os04, crystallizes in the space group forming a sixfold helical chain arrangement of nearly octahedral Os02F, molecules. Oxygen or fluorine atoms are partially disordered. The cis orientation of the two oxygen atoms is established by means of NMR, vibrational spectroscopy, and X-ray data.

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