Cocrystallization of Binuclear Iron(III) Porphyrins with C₆₀: Bending of μ-O{Fe^III(Octaethylporphyrin)} and the First Structure of the Iron(III) Octaethyloxophlorin Dimer

Black crystals of C60·μ-O{FeIII(OEP)}2·C6H6 and 2C60·{FeIII(OEPO)}2·4C6H6 suitable for single-crystal X-ray diffraction studies have been obtained by growth from benzene solutions of the appropriate binuclear metalloporphyrin and the fullerene. C60·μ-O{FeIII(OEP)}2·C6H6 crystallizes with two molecules of μ-O{FeIII(OEP)}2, two fully ordered molecules of C60, and two molecules of benzene in the asymmetric unit. Each independent molecule of μ-O{FeIII(OEP)}2 makes close contact with two fullerene molecules. In C60·μ-O{FeIII(OEP)}2·C6H6 the Fe−O−Fe angles (150.18(11)° and 151.89(11)°) are markedly bent with a benzene molecule wedged into the opening between the two porphyrins, whereas in the triclinic and monoclinic polymorphs of μ-O{FeIII(OEP)}2 the Fe−O−Fe angles are more nearly linear (172.16(17)° and 176.2(2)°, respectively). The structure of 2C60·{FeIII(OEPO)}2·4C6H6 consists of a centrosymmetric {FeIII(OEPO)}2 molecule in which the two macrocycles are connected to one another through axial coordination of the meso-oxygen atoms to iron ions in the neighboring porphyrin. Each molecule of {FeIII(OEPO)}2 engages a fullerene on its two exposed faces. The basic geometry of the central core of {FeIII(OEPO)}2 is similar to that of the previously characterized {InIII(OEPO)}2, but the distortion of the two macrocycles is greater in the former due to the shorter Fe−N and Fe−O bonds.