Synthesis, Characterization, and Autoreduction of a Highly Electron-Deficient Porphycenatoiron(III) with Trifluoromethyl Substituents

The synthesis of the first fluorine-containing iron porphycenes, 2,7,12,17-tetraethyl-3,6,13,16-tetrakis(trifluoromethyl)porphycenatoiron(III) chloride [FePc(EtioCF₃)]Cl and its μ-oxo dimer [FePc-(EtioCF ₃)]₂O and their characterizations are reported. The crystal structure of [FePc(EtioCF₃)]₂O displays a severe saddled distortion of the porphycene framework due to the steric and electronic effects of the CF₃ substituents. The oxidation and reduction potentials for then μ-oxo dimer are significantly more positive compared to those observed for the reference μ-oxo dimer of the iron porphycenes and porphyrins having no electron-withdrawing substituent. Moreover, the ¹H and ¹⁹F NMR spectra of [FePc(EtioCF₃)] ₂O demonstrated that the μ-oxo dimer is readily converted into the monomeric ferrous complex in pyridine-d₅ through autoreduction for 1 day, although the reduction of the reference iron porphycenes and porphyrins are not observed in pyridine. These results indicate that the trifluoromethylated iron porphycene is a highly electron-deficient complex with a pyrrolic macrocycle ligand.