One Carbon Ring Expansion of Bipyrrole to Bipyridine Enables Access to a π-Extended, Non-innocent, Corrole-like Ligand

초록

A pi-extended, diaza-triphenylene embedded, mono-anionic corrole analogue and its Ni-II complex were synthesized from a diaza-triphenylene precursor, which was obtained from a double one-carbon insertion into a naphthobipyrrole diester. Following conversion to the corresponding activated diol and acid-catalyzed condensation with pyrrole, subsequent reaction with pentafluorobenzaldehyde afforded mono-anionic, pi-extended bipyricorrole-like macrocycle. Attempted Ni-II insertion with Ni(OAc)(2) center dot 4H(2)O resulted an ESR active, Ni-II bipyricorrole radical complex, which was converted to a stable cationic NiII complex upon treatment with [(Et3O)(+)(SbCl6)(-)]. Both complexes were characterized by H-1 and C-13 NMR, UV/Vis spectroscopy and single crystal X-ray diffraction analysis. The Ni-II bipyricorrole radical complex is converted to a cationic Ni-II complex by single-electron reduction using cobaltocene. Both the cationic Ni-II complex and the radical Ni-II complex exhibited ligand-centered redox behavior, whereas the Ni-II remains in the +2 oxidation state.

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