Protonation of Ferrocene Derivatives with Strong Acids. Kinetic Relationships of the Redox Isomerism of Ferrocenylcarbenium Ions

The kinetics of redox isomerization of ferrocenylcarbenium ions obtained via protonation of ferrocene derivatives with perchloric acid in dioxane has been studied by means of electron absorption spectroscopy method from accumulation of ferrocenium cations. It has been shown that the dependences of the rate of ferrocenium cations accumulation on the components concentration is extremal in certain cases and is determined by the nature of metal complex and the initial ratio of the metal complex and acid. Stabilization of carbocations via their solvation with acetonitrile, DMF, and DMSO as well as via coordination with the starting compound leads to partial or complete loss of their ability to redox isomerization. Schemes of the metal complexes protonation and results of their kinetic analysis confirming the obtained concentration dependencies are given.