SOLIDS CONTAINING TETRAHALOPHOSPHONIUM CATIONS - AN INVESTIGATION USING P-31 AND B-11 MAGIC-ANGLE SPINNING NMR AND RAMAN-SPECTROSCOPY

A variety of solid complexes containing PCl4+ or PBr4- has been studied by magic-angle spinning (MAS) P-31 and B-11 NMR (the latter for complexes containing anionic tetrahaloborate). Linewidths give information about motion of the ions and it is concluded that this is inhibited when single-halide anions (Cl- or Br-) are present. Influences on the chemical shifts are discussed, and the results are compared with available Raman spectroscopic data. Detailed NMR and Raman spectroscopic studies have been carried out on samples containing the series of mixed-halogen cations [PCl(n)Br4-n+](0 less-than-or-equal-to n less-than-or-equal-to 4). Variable-temperature and sublimation experiments indicate reversible equilibria between species containing single-halide anions and those containing only polyatomic anions for products from PCl3/BCl3/Br2 reactions. The relative sensitivities of MAS NMR and Raman spectroscopy in the analysis of these systems are discussed.