6.

B3LYP*/STO-ZORA-TZ2P MO energy level diagrams of Re porphyrins and corroles based on OLYP-D3 ground-state optimized geometries. Cor and Por refer to unsubstituted corrolato(3-) and porphyrinato(2-) ligands, respectively. Doubly occupied and unoccupied MO energy levels are indicated in blue and red, respectively.