The fluoride ion donor properties of OsO3F2 have been investigated. The salts [OsO3F][AsF6], [OsO3F][HF](2)[AsF6], mu-F(OsO3F)(2)[AsF6], [OsO3F][HF](2)[SbF6], and [OsO3F][HF][SbF6] have been prepared by reaction Of OsO3F2 with AsF5 and SbF5 in HF solvent and have been characterized in the solid state by Raman spectroscopy. The single-crystal X-ray diffraction studies Of [OsO3F][AsF6] (P2(1)/n, a = 7.0001(11) Angstrom, b = 11.0620(11) Angstrom, c = 8.8629(13) Angstrom,beta = 92.270(7)degrees, Z = 4, and R-1 = 0.0401 at -126 degreesC), [OsO3F][SbF6] (P2(1)/c, a = 5.4772(14) Angstrom, b = 10,115(3) Angstrom, c = 12.234(3) Angstrom, beta = 99,321(5)degrees, Z = 4, and R-1 = 0.0325 at -173 degreesC), [OsO3F][HF](2)[AsF6] (P2(1)/n, a = 5.1491(9) Angstrom, b = 8,129(2) Angstrom, c = 19.636(7) Angstrom, beta = 95,099(7)degrees, Z = 4, and R-1 = 0.0348 at -117 degreesC), and [OsO3F][HF][SbF6] (Pc, a = 5.244(4) Angstrom, b = 9.646(6) Angstrom, c =. 15.269(10) Angstrom, beta = 97,154(13)degrees, Z = 4, and R-1 = 0.0558 at -133 degreesC) have shown that the OsO3F+ cations exhibit strong contacts to the anions and HF solvent molecules giving rise to cyclic, dimeric structures in which the osmium atoms have coordination numbers of 6. The reaction of OsO3F2 with neat SbF5 yielded [OsO3F][Sb3F16], which has been characterized by F-19 NMR spectroscopy in SbF5 and. SO2CIF solvents and by Raman spectroscopy and single-crystal X-ray diffraction in the solid state (P42(1)m, a = 10.076(6) Angstrom, c = 7.585(8) Angstrom, Z = 2, and R-1 = 0.0858 at -113 degreesC). The weak fluoride ion basicity of the Sb3F16- anion resulted in an OsO3F+ cation (C-3v point symmetry) that is well isolated from the anion and in which the osmium is four-coordinate, The geometrical parameters and vibrational frequencies Of Oso(3)F(+), ReO3F, mu-F(OsO3F)(2)(+), (FO3Os--FPnF(5))(2), and (FO3Os--(HF)(2)--FPnF(5))(2) (Pn = As, Sb) have been calculated using density functional theory methods.