Three new verdoheme analogues with weakly coordinating anions, [(OEOPFeX)-X-II], where OEOP is the monoanion of octaethyloxoporphyrin and X = PF6, ClO4, and BF4, have been synthesized and characterized by spectroscopic methods. H-1 NMR spectroscopy reveals that the [(OEOPFeX)-X-II] species are paramagnetic, and the iron is five-coordinate (S = 2). The oxidation of [(OEOPFePF6)-P-II] with dioxygen yields [(OEOPFe)(2)O](PF6)(2). The structure of (mu-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) angstrom. The oxygen atom sits on the inversion center, and the average axial Fe-O bond length is 1.756(3) angstrom. The average displacement of the iron(III) atom from the mean porphinato core is 0.60 angstrom. Crystal data: crystal system, monoclinic; a = 8.7114(10) angstrom; b = 26.102(4) angstrom; c = 15.8323(14) angstrom; = 104.134(6)degrees; space group P2(1)/c; V = 3491.1(7) angstrom(3); Z = 2; R1 = 0.0546, wR2 =0.1145 for data with 1 > 2 sigma(I).