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A small, colorless, single-crystal with appreciable vapor pressure at room temperature was presumed to be a new oxyfluoride compound of osmium. An X-ray study on a precession camera at a variety of temperatures from 20 to -100°C with many recrystallizations of the material revealed that it was dimorphic. One structure is monoclinic in space group C2/c with a unit cell nearly identical to that reported for OsO4. The second structure is cubic, a = 8.595 Å, Z = 8, space group P
3n, with an extraordinary assortment of systematic absences which yield the most remarkable diffraction patterns the writer has ever encountered. The observations are accounted for by a structure comprising 8 tetrahedral molecules with the anions in cubic close packing at an anion-anion distance of 3.04 Å and with an Os-anion distance of 1.86 Å. The most likely possibilities for the chemical composition appear to be OsO2F2 or OsO3F.
3n, with an extraordinary assortment of systematic absences which yield the most remarkable diffraction patterns the writer has ever encountered. The observations are accounted for by a structure comprising 8 tetrahedral molecules with the anions in cubic close packing at an anion-anion distance of 3.04 Å and with an Os-anion distance of 1.86 Å. The most likely possibilities for the chemical composition appear to be OsO2F2 or OsO3F.
