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(EtioCF3)]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
the 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.