The large in the small: The iodination of the corrole ring

Iodination is a valuable functionalization of the corrole ring, enabling further modifications of peripheral substituents and enhancing optical properties, such as efficient phosphorescent emission due to the heavy atom effect. In this study, we investigated the iodination of 5,10,15-tris(pentafluorophenyl)corrole and its corresponding hydroxy silicon complex using N-iodosuccinimide (NIS) as the iodinating reagent. The nature of the reaction products strongly depended on the equivalents of NIS used. When two equivalents of NIS were applied to the free-base corrole, the main product was the 2,3,17-triiodo derivative. In contrast, the reaction on the corresponding silicon complex required five NIS equivalents, yielding a triiodo compound. Attempts to introduce additional iodine atoms into the free-base corrole by increasing the amount of NIS resulted in macrocycle ring opening, forming linear tetrapyrroles. In the case of the silicon complex, efforts to achieve full iodination led to the formation of an isocorrole derivative. To the best of our knowledge, this is the first reported example of such a species derived from 5,10,15-tris(pentafluorophenyl)corrole.