Acid-Mediated Migration of Bromide in an Antiaromatic Porphyrinoid: Preparation of Two Regioisomeric Ni(II) Bromonorcorroles

The regioselective halogenation of porphyrinoids is critical for their selective functionalization, which enables the fine tuning of their electronic and optical properties. Here we report the synthesis of two regioisomeric Ni­(II) bromonorcorroles on the basis of the acid-induced migration of the bromo substituent. Treatment of Ni­(II) dimesitylnorcorrole with N-bromosuccinimide (NBS) selectively afforded Ni­(II) 3-bromonorcorrole, which was further converted into Ni­(II) 2-bromonorcorrole upon treatment with hydrogen bromide. In addition, the reaction of Ni­(II) dimesitylnorcorrole with an excess amount of NBS afforded the octabrominated product. The reaction mechanism of the bromination reaction of Ni­(II) dimesitylnorcorrole was investigated by theoretical calculations.