Shaping Antiaromatic π-Systems by Metalation: Synthesis of a Bowl-Shaped Antiaromatic Palladium Norcorrole.

The synthesis of a bowl-shaped antiaromatic molecule was achieved through the deformation of a planar antiaromatic porphyrinic π-conjugation system by insertion of palladium into the small cavity of a metal-free norcorrole. The bowl-to-bowl inversion dynamics of the antiaromatic Pd-coordinated norcorrole was determined by variable-temperature 1 H NMR spectroscopy. The metal-free norcorrole was prepared from acid-induced demetalation of a copper norcorrole, which was obtained from the intramolecular coupling of a bis(diiododipyrrin) copper complex with copper thiophenecarboxylate.