The electrooxidation of the tetraphenylborate ion revisited

Abstract

The electrochemistry of the tetraphenylborate ion, BPh₄⁻, has been studied by cyclic voltammetry and coulometry in water, methanol, ethanol, acetonitrile, acetone, dimethylformamide and dichloromethane under an N₂ atmosphere. While a one-electron and somewhat irreversible oxidation (with an E_1/2 of 0.87 V vs. SCE at a glassy carbon electrode) is observed in dichloromethane, eqn. (i), the oxidation is somewhat complicated in all other solvents by the occurrence of several consecutive reactions. E_pa, the anodic peak potential in cyclic voltammetry, changes from 0.41 V vs. SCE in water to 0.94 V vs. SCE in dimethylformamide at a glassy carbon electrode. The variation in E_pa with solvent (S) is explained by invoking reaction (ii). The coulometric results in solvents other than dichloromethane indicate a disproportionation of S–BPh₃, eqn. (iii).