New Class of Verdoheme Analogues with Weakly Coordinating Anions:  The Structure of (μ-Oxo)bis[(octaethyloxoporphinato)iron(III)] Hexafluorophosphate

Three new verdoheme analogues with weakly coordinating anions, [OEOPFeIIX], where OEOP is the monoanion of octaethyloxoporphyrin and X = PF6, ClO4, and BF4, have been synthesized and characterized by spectroscopic methods. 1H NMR spectroscopy reveals that the [OEOPFeIIX] species are paramagnetic, and the iron is five-coordinate (S = 2). The oxidation of [OEOPFeIIPF6] with dioxygen yields [(OEOPFe)2O](PF6)2. The structure of (μ-oxo)bis[(octaethyloxoporphinato)iron(III)] has been determined by X-ray diffraction analysis. The eight Fe−N bond distances have an average value of 2.077(3) Å. The oxygen atom sits on the inversion center, and the average axial Fe−O bond length is 1.756(3) Å. The average displacement of the iron(III) atom from the mean porphinato core is 0.60 Å. Crystal data: crystal system, monoclinic; a = 8.7114(10) Å; b = 26.102(4) Å; c = 15.8323(14) Å; β = 104.134(6)°; space group P21/c; V = 3491.1(7) Å3; Z = 2; R1 = 0.0546, wR2 =0.1145 for data with I > 2σ(I).