Characterisation of the Tetrahalophosphonium Cations Pbr N

The novel tetrahalophosphonium salts PBr4 AsF6 , PI4 AlCl4 and PI4 EBr4 (E = Al, Ga) have been synthesised. A variety of solid complexes containing PBr4 (e.g. PBr4 AsF6 , PBr4 AlBr4 PBr4 GaBr4 ), PI4 (e.g. PI4 AlCl4 , PI4 AlBr4 , PI4 GaBr4 ) or the mixed species PBrnI4 n (0 ≤ n ≤ 4, containing AlBr4 , GaBr4 , AsF6 or SbF6 ) have been studied by solid-state P MAS NMR and vibrational spectroscopy. The influence of the counter-ion on the chemical shift and the vibrational frequencies are discussed. The crystal structures of PI4 AlCl4 , PI4 AlBr4 and PI4 GaI4 are reported. Evidence for the existence of the hitherto unknown mixed bromoiodophosphonium cations PBr3I , PBr2I2 and PBrI3 has been confirmed by spin–orbit corrected density functional calculations of isotropic P chemical shifts for PBrnI4 n .