Electronic Structure of Copper Corroles

The ground state electronic structure of copper corroles has been a topic of debate and revision since the advent of corrole chemistry. Computational studies formulate neutral Cu corroles with an antiferromagnetically coupled CuII corrole radical cation ground state. X‐ray photoelectron spectroscopy, EPR, and magnetometry support this assignment. For comparison, CuII isocorrole and [TBA][Cu(CF3)4] were studied as authentic CuII and CuIII samples, respectively. In addition, the one‐electron reduction and one‐electron oxidation processes are both ligand‐based, demonstrating that the CuII centre is retained in these derivatives. These observations underscore ligand non‐innocence in copper corrole complexes. Innocent until proven guilty: The electronic structure of Cu corroles is studied using a variety of techniques in conjunction with DFT calculations. Given this data, the compound is best described as an antiferromagnetically coupled CuII corrole radical cation. Electrons are added to or removed from the corrole ligand in these redox processes, preserving the CuII centre. This result underscores corrole non‐innocence in these compounds.