A multinuclear magnetic resonance study of the tetraphenylarsonium and tetraphenylphosphonium tetraphenylborates in nonaqueous solvents

Abstract

Arsenic-75, phosphorus-31, boron-11, carbon-13 and ^lH n.m.r. measurements are reported for Ph₄As⁺, Ph₄P⁺ and Ph₄B^- ions in a number of nonaqueous solvents. The resonance frequencies of the first three nuclei are very nearly independent of the solvent and of the salt concentration indicating an effective shielding of the central atom from the solvent by the four phenyl groups. In contrast the resonance frequencies of the ortho, meta and para carbons and protons of the phenyl rings vary with the solvent. The resonances of the cationic and the anionic carbons and protons are different and the differences are solvent-dependent. The results indicate that the two cations and the anion are solvated to a different extent and that the 'reference electrolyte' assumption, used to obtain single ion transfer activity coefficients, has to be used cautiously.