Antimony(III) Fluoride Fluorosulfates: Syntheses and Molecular Structures of Antimony(III) difluoride fluorosulfate [SbF2(SO3F)]x, Antimony(III) Fluoride Bis(fluorosulfate) [SbF(SO3F)2]x, and Antimony(III) Tris(fluorosulfate) [Sb(SO3F)3]x

Article abstract of DOI:10.1021/ic00116a005

Following unsuccessful attempts to confirm the existence of previously reported antimony(I) fluorosulfate, Sb(SO3F), the reaction of antimony and fluorosulfuric acid is reinvestigated and synthetic routes are developed that allow the preparation of polymeric [SbF2(SO3F)]x, [SbF(SO3F)2]x, and [Sb(SO3F)3]x. Recrystallization from fluorosulfuric acid is found to produce single crystals of all three materials, which are suitable for molecular structure determinations by single-crystal X-ray diffraction. Crystals of [SbF2(SO3F)]x are orthorhombic, a = 13.4035(6) ?, b = 7.1852(6) ?, c = 5.0239(9) ?, Z = 4, and space group Pna21. Crystals of [SbF(SO3F)2]x are monoclinic, a = 10.7302(8) ?, b = 4.899(1)?, c = 13.671(1) ?, β = 111.253(7)°, Z = 4, space group P21/c. Crystals of [Sb(SO3F)3]x are hexagonal, a = 9.5718(9) ?,c = 17.283(1) ?, Z = 6, and space group P65. Data for all three compounds were collected to high resolution (Mo radiation, 2Θmax = 100°) in order to provide accurate structural information. The structures were solved by Patterson ([SbF2(SO3F)]x and [SbF(SO3F)2]x) or direct methods ([Sb(SO3F)3]x) and were refined by full-matrix least-squaresprocedures to R = 0.025, 0.028, and 0.030 (Rw = 0.026, 0.027, and 0.027) for 1807, 4572, and 2675 reflections with I >= 3σ(F**2), respectively. The three structures, together with the previously reported structure of [SbF3]x, allow a detailed comparison for all four members of theseries [SbFn(SO3F)3-n] for n = 0, 1, 2, or 3. In all structures, fluorines function as asymmetrical, bidentate bridges between two different antimony atoms, while the fluorosulfates are found to form asymmetric O-tridentate bridges. Hence the coordination number for antimony increases from 6 for [SbF3]x. to 7 for [SbF2(SO3F)]x, 8 for (SbF(SO3F)2]x, and 9 for [Sb(SO3F)3]x. All coordination geometries are highly distorted. According to Sb-O or Sb-F bond distances, the bonds are classified as primary (.apprx.2.0 .+-. 0.1 ?), intermediate (.apprx.2.5 .+-. 0.1 ?), and secondary (.apprx.2.9 .+-. 0.1 ?). The primary coordination geometries are trigonal pyramidal for SbF3, [SbF(SO3F)2]x, and [Sb(SO3F)3]x and distorted square pyramidal for [SbF2(SO3F)]x.