Kinetics of the reaction of nickel(II) ion with pyridine-2-azodimethylaniline: solvent effects and correlations

Abstract

Rates and activation parameters for the reaction of pyridine-2-azodimethylaniline (pada) with Ni^II ions have been measured for water and seven other solvents. A comparison of the results with the corresponding kinetics of exchange of solvent molecules at the Ni^II ion reveals a wide variation in the ratio of rates for ligand-substitution and solvent-exchange. Approximate correlations linking these ratios with properties of the solvent lend support to the previously-proposed “concerted interchange” model for ligand-substitution, which emphasises the importance of solvent structure as an influence on the mechanism of reaction.