Electronic structures and reactivities of corrole-copper complexes

The spectroscopic and electrochemical examination of the mononuclear copper complexes of 5,10,15-tris(pentafluorophenyl)corrole and 5,10,15-tris(2,6- dichlorophenyl)corrole (1a and 2a, respectively) and of the corresponding dinuclear corrole dimers 1b and 2b reveal the existence of two almost degenerate electronic states. The lower state consists of copper(III) ions coordinated by closed-shell corrolato trianions and the higher state is composed of copper(II) ions chelated by open-shell corrolato dianions, The contributions from both states are evident in the molecular structure of monomeric and mononuclear 2a, which displays a distorted square-planar coordination geometry around the metal ion and short Cu-N bond lengths typical of copper(III), together with some non-equivalence of the C_α-C_meso bond lengths that might reflect the open-shell character of the macrocycle. The latter state is most likely to be responsible for the dimerization process.