The resonances in the 19F nuclear magnetic resonance (n.rn.r.), spectrum of antimony pentafluoride have been reassigned and it is shown that the fine structure observed in the spectrum of antimony pentafluoride in various inert solvents can only be explained by considering the effects of magnetic nonequivalence. Solutions of t-butyl fluoride and tetra-n-butylammonium hexafluoroantimonate in excess SbF,/SO,CIF are shown to contain the Sb3F16-and Sb4Fzl-anions which have cis-fluorine bridged structures. The coupling constants and chemical shifts in the n.m.r. spectra of Sb3FI6-, Sb4Fzl-, (SbF,), and 1 :1 and 2:l complexes of SbF, are compared and discussed.

19F nuclear magnetic resonance (n.m.r.) has been used to study the reactions occurring in the systems SbCl5–SbF5–SO2ClF, SO2Cl2–SbF5–SO2ClF, COF2–SbF5–SO2ClF, COF2–AsF5–SO2ClF, and COClF–SbF5–SO2ClF. Ionization occurs in SbCl5–SbF5–SO2ClF, yielding antimony chloro- and chloro-fluorocations and antimony polyfluoroanions. Donor-acceptor complexes are formed between SbF5 and SO2Cl2, COF2 or COClF at low temperatures and also between AsF5 and COF2. In all the complexes the ligand is oxygen-bonded. At higher temperatures halogen exchange and ionization occurs in SO2Cl2–SbF5–SO2ClF and COClF–SbF5–SO2ClF giving SO2ClF and COF2 complexes, respectively, together with antimony cations and polyfluoroanions. The alkyl chloride –SbF5 reaction is also shown to give chlorine-containing cations of antimony.

Fluorine nuclear magnetic resonance spectra have been obtained for the t-butyl fluoride–SbF5, t-butyl chloride–SbF5, tetraethylammonium hexafluoroantimonate–SbF5, and cesium fluoride–SbF5 systems, both with and without SO2 solvent. In SO2 solution the anion is Sb2F11− for all the systems, any remaining SbF5 being converted to SbF5•SO2. It is concluded that in the systems that do not contain SO2, higher polymeric anions SbnF5n+1−, where n > 2, are present. t-Butyl chloride and t-butyl fluoride give the t-butyl carbonium ion, as has been previously reported. Tetrabutylammonium and benzyltri-methylammonium cations appear to decompose to a carbonium ion and an adduct SbF5•NR3 in the presence of SbF5.

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