Carbon–hydrogen bond activation of arenes and alkylarenes by electron transfer followed by oxygen transfer catalyzed by vanadium substituted polyoxometalates – A comparative study of the reactivity of different polyoxometalate compounds

• C–H bond activation of arenes and alkyl arenes is initiated by electron transfer.
• Study of electron transfer between anthracene and vanadium-polyoxometalates.
• Electron transfer is a function of oxidation potential, charge and structure.
• There is a correlation between thermodynamic and kinetic free energies.
• The efficiency of oxygen transfer is unrelated to the electron transfer activity.

The reactivity of various vanadium-substituted polyoxometalates with different structures and oxidation potentials was compared for the electron transfer-oxygen transfer oxidation of anthracene and dihydroanthracene as model substrates. Electron transfer initiates the C–H bond activation. Analysis of reactivity via an outer sphere electron transfer model demonstrates that in addition to the oxidation potential, the polyoxometalate structure and charge are important parameters in the electron transfer reaction. A further comparative study for electron transfer and oxygen transfer reactivity showed that the eventual formation of the oxygenated product, although initiated by electron transfer was dependent on other factors.

The correlation between the thermodynamic and transition state or kinetic free energies describing the electron transfer reaction between anthracene and a series of vanadium containing polyoxomolybdates.Figure optionsDownload as PowerPoint slide