Supramolecular structure of five-coordinate [(4-methyl-2,6-dinitrophenolato)(octaethylporphinato)iron(III)] heme complex

The crystallographic and spectroscopic characterization of the phenolate complex of [(4-methyl-2,6-dinitrophenolato)(2,3,7,8,12,13,17,18-octaethylporphinato)Fe(III)], [FeIII(OEP)(DNOC)] is reported. The 4-methyl-2,6-dinitrophenol (DNOC) ligand was coordinating with the FeIII(OEP) moiety through the phenylato-O-atom. The complex crystallizes in the triclinic P-1 with Z=2. The crystallographic information showed the average Fe—Np distance of 2.053(18) Å, with the Fe displacement from the 24 atoms porphyrin plane of 0.41(6) Å, and the Fe—O distance of 1.881(15) Å showing a five-coordinate square-pyramidal geometry. The characteristic of the formation of the Fe—O bond was found near 537 cm-1 for IR spectra and the n4 band was near 534 cm-1 for Raman spectra. The major supramolecular interactions involved an intermolecular hydrogen bond C—H···O with a minimum distance of 2.732(5) Å, and the shortest plane-plane contact distance of 3.689(3) Å. The FT-IR characteristic showed the new band near 3400 cm-1, which was broadened due to the formation of hydrogen bonds. The role of these weak C—H···O hydrogen bonds concerted to stabilized the crystal packing in the heme complex. Thus, the number of excellent hydrogen bond acceptors of the axial ligand contributes to its supramolecular structure.