ИСТИНА

Reactions of the iodonium derivative of cobalt bis(dicarbollide) anion [μ-8,8’-I-3,3’-Co(1,2-C2B9H10)2] (1) with Lewis bases in aromatic solvents were studied. The reactions proceed through the iodonium bridge opening and character of the reaction products depends on the nature of Lewis base and solvent used. The reactions with conventional Lewis bases 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 result in activation of the aromatic C-H bond with formation of the corresponding aryl derivatives [8-Ar-8’-I-3,3’-Co(1,2-C2B9H10)2]-. The activated aromatics, such as toluene, o- and m-xylenes could react with 1 without Lewis bases, whereas the C-H activation of sterically hindered activated aromatics (p-xylene, mesitylene) requires the presence of hindered Lewis bases. The obtained aryl derivatives [8-Ar-8’-I-3,3’-Co(1,2-C2B9H10)2]- were found to have transoid conformation both in the solid state and in solution due to intramolecular hydrogen CHcarb…IB bonds and aromatic CHcarb…π interactions between the dicarbollide ligands. Reactions of 1 with halogen alkanes proceed through activation of the C-X (X = Cl, Br) bonds with formation of the corresponding halogen derivatives [8-X-8’-I-3,3’-Co(1,2-C2B9H10)2]-. The Lewis acidity of the quasi-borinium cation formed on breakage of the iodonium bridge was estimated using Beckett-Gutmann method. According to the Gutmann acceptor number AN = 112 this quasi-borinium cation belongs to the most strong boron Lewis acids.