The preparation and crystal structure of the 3:1 adduct of antimony trifluoride and antimony pentafluoride containing the (Sb3F8+)∞ cation
Abstract
Antimony pentafluoride and SbF3·SbF5 are reduced by an excess of phosphorus trifluoride, in liquid arsenic trifluoride to form (SbF3)3SbF5 together with possibly small amounts of antimony trifluoride. Antimony pentafluoride is similarly reduced by an excess of elemental iodine to (SbF3)3SbF5 but with larger amounts of antimony trifluoride. A single crystal X-ray diffraction study of (SbF3)3SbF5 shows that it is monoclinic, space group P21/m, with cell dimensions a= 10.895(3), b= 10.941(3), c= 4.772(1)Å, β= 96.66(3)°, and Z= 2. The structure was refined to a final R of 0.039 for 1 694 reflections. The structure consists of discrete SbF6– anions and parallel strands of (Sb3F8+)∞ which lie along the b axis. The polymeric strand can be considered to be composed of SbF3 and Sb2F5+ units joined by antimony–fluorine bridges [2.270(5), 2.414(5)Å]. The vibrational spectrum of (SbF3)3SbF5 is reported.