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.