Two-electron redox chemistry of p -nitro- and p -cyanobenzene diazohydroxides

The electrochemistry of aryl diazonium salts is usually dominated by one-electron reduction, loss of dinitrogen, and the grafting of aryl radicals onto the electrode. In contrast, -nitro- and -cyanobenzene diazonium salts dissolved in mixed aqueous-acetonitrile solvents showed diffusion-limited, quasi-reversible, two-electron cyclic voltammetry. Voltammetric pH-dependence and spectrophotometric kinetic studies suggest that the basicity and low polarity of the aqueous solvent mixture has revealed the biologically-significant interconversion of diazohydroxide and diazene.