Synthesis of cationic arene complexes of 7 and 8 group metals in strong protonic acids

A review of works on the synthesis of complexes mentioned in the title published in the late 30 years is presented. Strong protonic acids are shown to be quite effective reagents and perfect medium for the formation of organometallic cationic complexes by means of arene substitution for halide, carbonyl and diene ligands. The method is convenient and simple, it is realized in one stage under comparatively mild conditions and it is based on available initial compounds. In the process of arene complex formation the oxidation state of metal may increase. The method permitted by obtain a series of previously unknown bridge cationic arene complexes of Ru, Co, Rh, Ir