A Stable Antiaromatic 5,20-Dibenzoyl [28]Hexaphyrin(1.1.1.1.1.1): Core AuIII Metalation and Subsequent Peripheral BIII Metalation

5,20-Dibenzoyl [28]hexaphyrin(1.1.1.1.1.1) was synthesized as the first hexaphyrin bearing meso-aroyl sub-stituents. The meso-dibenzoyl substituents are hydrogen-bonded with the pyrrolic protons to stabilize an antiaromatic dumbbell conformer. Core metalation of this hexaphyrin with Au-III afforded rectangular and aromatic [26]hexaphyrin bis-Au-III complexes, the major isomer of which was reduced with NaBH4 to give its antiaromatic 28 pi bis-Au-III complex. This complex allowed facile peripheral metalation with B-III owing to the peripheral benzoyl substituents.