Crystal structure of meso-tetrakis(4-nitrophenyl)porphyrin nitrobenzene disolvate

The porphyrin core of the title centrosymmetric compound, C44H26N8O8·2C6H5NO2, is approximately planar, the maximum deviation being 0.069 (3) Å. The planes of the benzene rings of the nitrophenyl substituents are almost perpendicular to the porphyrin mean plane, making dihedral angles of 73.89 (9) and 89.24 (9)°. The two pyrrole ring H atoms are equally disordered over the four pyrrole ring N atoms. In the crystal, weak C—H⋯O and C—H⋯N hydrogen bonds link the porphyrin molecules into a three-dimensional supramolecular network. The nitrobenzene solvent molecules are linked by weak C—H⋯O hydrogen bonds into supramolecular chains propagating along the a-axis direction.


S2.2. Refinement
H atoms were placed in calculated positions with C-H = 0.93 Å and N-H = 0.86 Å, and refined in riding mode with U iso (H) = 1.2 U eq (N,C). Each amino H atom is equally disordered over two positions.

S3. Results and discussion
Porphyrins and metalloporphyrins attract attention of the researchers in many aspects, such as building blocks for molecular cages (Meng et al., 2011), catalysts (Odo et al., 2009 or photofunctional materials (Yan et al., 2009). Having continuing interest in study of polynuclear complexes (see, for example, Seredyuk et al., 2007, Moroz et al. 2012, in this paper we report the structure of meso-tetrakis(4-nitrophenyl)porphyrin, a precursor for polytopic bridging ligands (for example, Zha et al., 2013).
The 24-membered porphyrin moiety of the title compound is planar with a maximum deviation of C2 atom equal to ±0.130 (3) Å. The angle between adjacent pyrrole ring planes (C1-C4/N1 and C5-C13/N3) is 7.190 (11), and bond lengths and angles are close to those found for tetraphenylporphyrin (Silvers & Tulinsky, 1967). This suggests that the nitrophenyl substituents and/or packing effects influence the geometry of the porphyne ring.
The molecule of porphyrin contains two structurally different pairs of pyrrole rings. Despite two hydrogen atoms are disordered over four pyrrole rings, the two structurally non-equivalent pyrrole rings have somewhat different angles C-N-C equal to 107.20 (20)° and 108.30 (20)°.
The 4-nitrophenyl groups are rotated at angles of 73.89 (9)° and 89.24 (9)° with respect to the porphyrin mean plane, due to steric hindrance with the pyrrole-H atoms of the macrocycle.
The unit-cell packing along the a axis is shown in Fig. 2. There are no significant π-π interactions between the porphyrins. The 4-nitrobenzene groups around the porphyrin core apparently hinder interactions between the porphyrins.
The channels formed due to loose packing of porphyrins are occupied by nitrobenzene molecules. Molecular structure of the title compound with the atom-labeling scheme and 25% probability displacement ellipsoids.
Hydrogen atoms are omitted for clarity.

Figure 2
Projection of the crystal packing along a axis.

meso-Tetrakis(4-nitrophenyl)porphyrin nitrobenzene disolvate
Special details Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s 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 R-factors(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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq Occ.