Superacids [1,2] have for many years played a pivotal and unique role as reaction media in the generation of homoleptic metal-carbonyl cations as thermally stable salts. [3][4][5][6] In particular SbF 5 , the strongest molecular Lewis acid [7,8] and the conjugate Brønsted--Lewis superacid HF-SbF 5 , [1,2] have allowed the formation of a substantial number of salts with superelectrophilic, [9]