Bis(1-methylimidazole)[meso-α,α,α,α-tetrakis(o-nicotinamidophenyl)porphinato]iron(II)–1-methylimidazole–tetrahydrofuran (1/1/1.5)

The crystal structure of the bis(1-methylimidazole)-ligated iron(II) picket-fence porphyrin derivative [FeII(C68H44N12O4)(C4H6N2)2]·C4H6N2·1.5C4H8O is investigated.

In the title compound, [Fe II (C 68 H 44 N 12 O 4 )(C 4 H 6 N 2 ) 2 ]ÁC 4 H 6 N 2 Á1.5C 4 H 8 O, the central Fe II ion is coordinated by four pyrrole N atoms of the porphyrin core and two N atoms of the 1-methylimidazole ligands in the axial sites. One 1-methylimidazole and one and a half tetrahydrofuran solvent molecules are also present in the asymmetric unit. The complex exhibits a near planar porphyrin core conformation, in which the iron centre is slightly displaced towards the hindered porphyrin side (0.01 Å ). The average Fe-N p (N p refers to the pyrrole nitrogen atoms in the porphyrin) bond length is 1.990 (9) Å , and the axial Fe-N Im (N Im refers to the imidazole nitrogen atoms) bond lengths are 1.993 (3) and 2.004 (3) Å . The dihedral angle between the two coordinated 1-methylimidazole planes is 56.6 (2) . The dihedral angles between the 1-methylimidazole planes and the planes of the closest Fe-N p vector are 16.8 (2) and 39.8 (2) . N-HÁ Á ÁN and N-HÁ Á ÁO interactions are observed in the crystal structure.
The asymmetric unit of the title compound ( Fig. 1) contains one bis(1-methylimidazole) [meso-,,,-tetrakis(o-nicotinamidophenyl)porphinato]iron(II), one 1-methylimidazole and one and a half tetrahydrofuran lattice solvate molecules. Additional quantitative information on the structure is given in Fig. 2, which displays the detailed displacement of each porphyrin core atom (in units of 0.01 Å ) from the 24-atom mean plane. Averaged values of the chemically unique bond lengths (Å ) and angles ( ) are also shown. The title compound has a near planar porphyrin core conformation, in which the iron centre is slightly displaced towards the hindered porphyrin side (0.01 Å ). The dihedral angles formed by the 1-MeIm axial ligand planes and the closest Fe-N p vector are 16.8 (2) and 39.8 (2) . The dihedral angle between the two coordinated imidazole planes is 56.6 (2) , showing a relative perpendicular orientation. Fig. 2 also shows that the average N p -Fe-N p angle is ideal at 90.01 (9) , and the axial Fe-N Im bond lengths are 1.993 (3) and 2.004 (3) Å . The average Fe-N p distance of 1.990 (9) Å is a typical value for low-spin ferrous porphyrin derivatives (Scheidt & Reed, 1981).

Figure 2
A formal diagram of the porphyrinato core of the title compound. Averaged values of the chemically unique bond distances (in Å ) and angles ( ) are shown. The numbers in parentheses are the e.s.d.'s calculated on the assumption that the averaged values were all drawn from the same population. The perpendicular displacements (in units of 0.01 Å ) of the porphyrin core atoms from the 24-atom mean plane are also displayed. Positive values of the displacement are towards the hindered porphyrin side. The dashed line indicates the imidazole on the less hindered porphyrin side and the circles represent the positions of the methyl groups on the axial ligands. Table 1 Hydrogen-bond geometry (Å , ). Symmetry code: (i) x; y þ 1; z.

Figure 1
The molecular entities in the title compound, with displacement ellipsoids drawn at the 25% probability level. The 1-methylimidazole and tetrahydrofuran solvent molecules are omitted for clarity.

Figure 4
A view of the molecular packing of the title compound. Hydrogen atoms are omitted for clarity.