C−H Bond Activation of Arenes by [8,8′-μ-I-3,3′-Co(1,2-C<sub>2</sub>B<sub>9</sub>H<sub>10</sub>)<sub>2</sub>] in the Presence of Sterically Hindered Lewis Bases
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Reactions of the iodonium derivative of cobalt bis(dicarbollide) anion [μ-8,8′-I-3,3′-Co(1,2-C2B9H10)2] with Lewis bases in aromatic solvents were studied. The reactions proceed through the iodonium bridge opening, and the structure of the reaction products depends strongly on the nature of the Lewis base and solvent used. The reactions with conventional Lewis bases (L) give the corresponding products of Lewis base addition, [8-L-8′-I-3,3′-Co(1,2-C2B9H10)2], whereas the reactions with sterically hindered Lewis bases (L*) result in activation of the C−H bond of the aromatic solvent with formation of the corresponding aryl derivatives [8-Ar-8′-I-3,3′-Co(1,2-C2B9H10)2]−. Activated arenes, such as toluene, could react with [μ-8,8′-I-3,3′-Co(1,2-C2B9H10)2] without Lewis bases, whereas strongly deactivated arenes do not give C−H activation products even in the presence of sterically hindered Lewis bases.
