Crystal structure of bis(benzylamine-κN)[5,10,15,20-tetrakis(4-chlorophenyl)porphyrinato-κ4 N]iron(II) n-hexane monosolvate

The crystal packing of the FeII porphyrin derivative results in channels parallel to [010] where the n-hexane solvent molecules are located. UV–vis data of a CHCl3 solution and the solid of the title compound are also reported.


Chemical context
The structure of turnip cytochrome f has been determined on the basis of X-ray measurements (Martinez et al., 1996), showing that the -amino group of the Tyr-1 entity coordinates trans to the His-25 entity in the c-type heme protein. Thus, bisamine Fe II metalloporphyrins appear to be functionally significant as models for cytochrome f. On the other hand, it has been shown that the reaction of primary and secondary amines with iron(III) metalloporphyrins results in a basecatalysed one-electron reduction process and concomitant dissociation of the deprotonated amine radical (Del Gaudio & La Mar, 1978). It is also known that the addition of an excess of sterically unhindered alkylamines to an Fe(III) porphyrin derivative leads to bis(amine)-iron(II) porphyrins with the central metal cation in a six-coordination (Morice et al., 1998). Notably, the number of published structures of these type of iron(II) metalloporphyrins is small. In the Cambridge Structural Database (CSD, Version 5.35; Groom & Allen, 2014), only six amine porphyrin structures are reported, including [Fe II (TPP)(BzNH 2 ) 2 ] (TPP is the 5,10,15,20-tetraphenylporphyrinato ligand; Bz is benzyl) (Munro et al., 1999).

Structural commentary
The molecular structure of (I) is illustrated in Fig. 1. The Fe II cation is located on an inversion centre and shows an octahedral coordination environment. The equatorial plane is ISSN 2056-9890 formed by the four nitrogen atoms of the porphyrin moiety whereas the axial positions are occupied by the N atoms of the two benzylamine ligands.

Supramolecular features
The complex molecules are packed in such a way that channels are formed parallel to [010] in which the n-hexane molecules The structures of the molecular entities in the title compound. Displacement ellipsoids are drawn at the 60% probability level. H atoms have been omitted for clarity. [Symmetry code: (i) Àx + 1, Ày + 1, Àz + 1.]

Figure 2
Schematic representation of the porphyrin core illustrating the displacements of each atom from the 24-atom plane in units of 0.01 Å . are situated. The linkage of the molecular components in the crystal structure of (I) is accomplished by C-HÁ Á ÁCl, N-HÁ Á ÁCl hydrogen-bonding interactions as well as C-HÁ Á Á interactions (Figs. 3 and 4; Table 1). Each [Fe II (TPP-Cl)-(BzNH 2 ) 2 ] complex is linked to neighbouring complexes through N-HÁ Á ÁCl hydrogen bonds between the N3 atom of the benzylamine ligand and the Cl2 atom of a TPP-Cl moiety and by C-HÁ Á ÁCl interactions between the pyrrole C7 atom and the Cl2 atom. In addition, the phenyl C19 atom of the [Fe II (TClPP)(BzNH 2 ) 2 ] complex interacts with the centroid Cg1 of the (N1/C1-C4) pyrrole ring through C-HÁ Á Á interactions. The three-dimensional supramolecular network is consolidated by another C-HÁ Á Á intramolecular interaction involving the C31 atom of the n-hexane solvent molecule and the centroid Cg7 of the (C11-C16) phenyl ring.

Figure 3
A partial view of the crystal packing of (I), showing the linkage between the [Fe II (TPP-Cl)(BzNH 2 ) 2 ] complexes through C-HÁ Á ÁCl and N-HÁ Á ÁCl hydrogen bonds. The n-hexane solvent molecules have been omitted for clarity.

Figure 4
The crystal structure of the title compound plotted in a projection along [010]. Contacts between the entities are given as dashed lines.
recorded on a WinASPECT PLUS (validation for SPECORD PLUS version 4.2) scanning spectrophotometer. In Fig. 5 are illustrated the electronic spectra of the solid [Fe III (TPP-Cl)-(SO 3 CF 3 )] complex, used as starting material, and complex (I) which shows that the Soret band of the latter species is redshifted compared to the one of the starting material. The max values of the Soret and Q bands of (I) in the solid state and in chloroform solution are very close. These values also compare well with those of the related [Fe II (TPP)(L) 2 ] (L = 1-BuNH 2 , BzNH 2 , PhCH 2 CH 2 NH 2 ) species (Munro et al., 1999).