The Me3NB12Cl11• Radical: A Strong One-Electron Oxidizing Agent

Strong oxidizing agents often contain fluorine and are not compatible with substrates forming strong element-fluorine bonds. Therefore, there is need for new strong oxidizers. Cyclic voltammetric measurements on the weakly coordinating anion [Me3NB12Cl11](-) in liquid SO2 revealed an oxidation wave at +2.59 V versus Fc(0/+). The oxidation of Na[Me3NB12Cl11] with AsF5 in liquid sulfur dioxide gives the boron-cluster-based radical Me3NB12Cl11 center dot as a dark blue solid in quantitative yield. The radical was characterized by vibrational, NMR, and EPR spectroscopy and by its crystal structure. To explore the potential of the radical Me3NB12Cl11 center dot to act as a strong oxidizing agent, it was reacted with different compounds having high ionization energies. Thianthrene (ionization energy 7.8 eV) and hexabromobenzene (8.8 eV) were oxidized to the corresponding cations. The reaction with elemental iodine (9.3 eV) gave the [I-5](+) cation. These reactive cations are stabilized in the solid state by the weakly coordinating anion [Me3NB12Cl11](-), which was formed as a reduced product in the oxidation reactions.