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)

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) Angstrom, b = 7.1852(6) Angstrom, c = 5.0239(9) Angstrom, Z = 4, and space group Pna2(1). Crystals of [SbF(SO3F2)](x) are monoclinic, a = 10.7302(8) Angstrom, b = 4.899(1) Angstrom, c = 13.671(1) Angstrom, b = 111.253(7)degrees, Z = 4, space group P2(1)/c. Crystals of [Sb(SO3F)(3)](x) are hexagonal, a = 9.5718(9) Angstrom, c = 17.283(1) Angstrom, Z = 6, and space group P6(5). Data for all three compounds were collected to high resolution (Mo radiation, 2 theta(max) = 100 degrees) 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-squares procedures to R = 0.025, 0.028, and 0.030 (R(W) = 0.026, 0.027, and 0.027) for 1807, 4572, and 2675 reflections with I greater than or equal to 3 sigma(F-2), respectively. The three structures, together with the previously reported structure of [SbF3](x), allow a detailed comparison for all four members of the series [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 (similar to 2.0 +/- 0.1 Angstrom), intermediate (similar to 2.5 +/- 0.1 Angstrom), and secondary (similar to 2.9 +/- 0.1 Angstrom). 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).