A Stable Organic π-Radical of a Zinc(II)-Copper(I)-Zinc(II) Complex of Decaphyrin

A Zn^II-Cu^I-Zn^II heterotrimetal complex of decaphyrin was synthesized by stepwise metalations: metalation of a [46]decaphyrin with Zn^II ions to produce a 46π decaphyrin bis(Zn^II) complex and its subsequent metalation with Cu^II ion. In the second metalation step, it has been shown that Cu^II ion is reduced to a Cu^I ion in the complex and a dianionic bis(Zn^II) containing [46]decaphyrin ligand is oxidized to the corresponding monoanionic [45]decaphyrin ligand, indicating a non-innocent nature of the decaphyrin ligand. Despite the radical nature, the heterotrimetal complex is fairly stable under ambient conditions and exhibits almost no intermolecular magnetic interaction, owing to extensive delocalization of an unpaired electron in the large π-conjugated circuit of decaphyrin moiety. Radical racetrack: Cu^II metalation of a [46]decaphyrin bis(Zn^II) complex gave a Zn^II-Cu^I-Zn^II heterotrimetal complex of decaphyrin consisting of a central Cu^I ion and a monoanionic 45π radical of decaphyrin.