Mono- and diboron corroles: factors controlling stoichiometry and hydrolytic reactivity

The first example of a diboryl corrole complex, [(BF2)2(Br8T(4-F-P)C)](-) (Br8T(4-F-P)C = trianion of 2,3,7,8,12,13,17,18-octabromo-5,10,15-tris(4-fluorophenyl)corrole), has been isolated using the strongly electron-withdrawing and sterically crowded triaryl octabromocorrole ligand. Density functional theory (DFT) calculations show that the hydrolysis reaction producing the partially hydrolyzed complexes [B2OF2(Cor)](-) is more favored for the less sterically crowded triaryl corrole complexes. Monoboryl complexes BF2(H2Cor) (Cor = trianions of 5,10,15-triphenylcorrole (TPC), 5,10,15-tris(4-methylphenyl)corrole (T(4-CH3-P)C), 5,10,15-tris(4-trifluoromethylphenyl)corrole (T(4-CF3-P)C), and 5,10,15-tris(pentafluorophenyl)corrole (TPFPC)) were prepared and characterized. The experimental data are consistent with an out-of-plane dipyrrin coordination mode for these complexes, and DFT optimizations suggest that internal BF···HN hydrogen bonding may be significant in stabilizing these complexes. Further examples of the anionic diboron corrole [B2OF2(Cor)](-) containing the electron-withdrawing 5,10,15-tris(pentafluorophenyl)corrole (TPFPC) and the sterically hindered 10-(4-methoxyphenyl)-5,15-dimesitylcorrole (Mes2(4-MeOP)C) trianions are reported.