The Me₃ NB₁₂ Cl₁₁^. 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 [Me₃ NB₁₂ Cl₁₁ ]^- in liquid SO₂ revealed an oxidation wave at +2.59 V versus Fc^0/+ . The oxidation of Na[Me₃ NB₁₂ Cl₁₁ ] with AsF₅ in liquid sulfur dioxide gives the boron-cluster-based radical Me₃ NB₁₂ Cl₁₁^. 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 Me₃ NB₁₂ Cl₁₁^. 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 [I₅ ]⁺ cation. These reactive cations are stabilized in the solid state by the weakly coordinating anion [Me₃ NB₁₂ Cl₁₁ ]^- , which was formed as a reduced product in the oxidation reactions.