Chlorido(2,3,7,8,12,13,17,18-octaethylporphyrinato)iron(III) dichloromethane sesquisolvate

The title molecule, [Fe(C36H44N4)Cl]·1.5CH2Cl2, is a high-spin square-pyramidal iron(III) porphyrinate with an average value for the equatorial Fe—N bond lengths of 2.065 (3) Å and an axial Fe—Cl distance of 2.2430 (13) Å. The iron cation is displaced by 0.518 (1) Å from the 24-atom mean plane of the porphyrin ring. These values are typical for high-spin iron(III) porphyrinates.


Comment
The title compound (in the reported crystalline form) has been used for many years in the principal author's laboratory as a convenient starting material for many studies of porphyrin derivatives. The square-pyramidal coordination of the central irn(III) atom, with an average equatorial Fe-N distance of 2.065 (3) Å and 2.2430 (13) Å for the axial Fe-Cl distance, is typical for high-spin chloride derivatives (Scheidt, 2000). The iron atom is displaced by 0.518 (1) Å from the 24 atom mean plane and 0.468 (1) Å from the plane of the four nitrogen atoms. The core has a modest saddled conformation. The conformation of the the molecule with its eight peripheral ethyl groups is unusual with all eight groups pointing away from the axial chloride ligand (see Fig. 1), resulting in a molecule with a spider-like shape. This geometry leads to well-separated iron atoms with the closest Fe···Fe separation of 9.711 (3) Å that is larger than typical for OEP (OEP = octaethylporphyrin) derivatives.
Three different crystalline species containing the [Fe(OEP)Cl] moiety have been previously reported by Ernst et al. (1977), Olmstead et al. (1999) andSenge (2005). In comparison with the current derivative they have a different conformation of the peripheral ethyl groups.

Experimental
Iron(II) chloride was purchased from Fisher and H 2 OEP from Midcentury Chemicals. [Fe(OEP)Cl] was prepared by reaction of iron(II) chloride in dimethyl formamide as described by Adler et al. (1970)). Single crystals were obtained by slow evaporation of methylene chloride solutions.

Refinement
The H atoms attached to C atoms of the porphyrin ring were positioned geometrically and allowed to ride on their parent atoms, with a C-H distance of 0.93 Å and U iso (H) = 1.2U eq (C). Methylene and methyl H atoms were likewise positioned geometrically and refined as riding atoms, with C-H = 0.97 Å (methylene) and C-H = 0.96 Å (methyl) and U iso (H) = 1.2U eq (C).
One of the methylene chloride molecules of crystallization is disordered across the inversion center at [0.5, 0, 1] and has been modelled with half occupancy atoms. The other methylene chloride occupies a general position in the lattice and was modelled at full occupancy.
supplementary materials sup-2 Figures Fig. 1. : ORTEP diagram for [Fe(OEP)Cl] with atom labels and displacement ellipsoids at the 50% probability level. Methylene chloride solvent molecules and hydrogen atoms have been removed for clarity.

Special details
Experimental. Diffraction data were measured with an Enraf Nonius FAST area detector to 59.54 deg in 2 theta. With the hardware and software supplied for the diffractometer, the data collection process provides substantial redundancy but not necessarily completion up to the limiting resolution. At a resolution of 0.83 Å (52 deg in 2 theta) essentially full coverage of data were met. Successful and suitable refinement of the structure supports this.
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.
Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating Rfactors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.