Crystal structure of bis(4-nitroaniline-κN 1)(5,10,15,20-tetraphenylporphyrinato-κ4 N)cobalt(III) chloride dichloromethane monosolvate

The reaction of [CoIII(TPP)Cl] (TPP is the dianion of 5,10,15,20-tetraphenylporphyrin) with an excess of 4-nitroaniline in dichloromethane leads to the title compound, [CoIII(C44H28N4)(C6H6N2O2)2]Cl·CH2Cl2. The CoIII ion lies on an inversion centre and is octahedrally coordinated by two N atoms of the NH2 groups of the two 4-nitroaniline trans-axial ligands and four pyrrole N atoms of the porphyrin. The asymmetric unit contains one half of the [CoIII(TPP)(4-nitroaniline)2]+ ion complex, one chloride counter-ion (lying on a twofold rotation axis) and one half dichloromethane solvent molecule, where the C atom lies on a twofold rotation axis. The average equatorial Co—N(pyrrole) distance (Co—Np) is 1.982 (2) Å and the axial Co—N(4-nitroaniline) bond length is 2.006 (2) Å. The crystal packing is stabilized by an N—H⋯Cl hydrogen bond between the N atom of the amino group of the 4-nitroaniline axial ligand and the chloride counter-ion. The supramolecular architecture is further stabilized by weak C—H⋯π interactions.

Cg7 and Cg8 are the centroids of the C11/C12-C16 and C17/C18-C22 rings, respectively.  The crystal packing of the title compound is stabilized by N-H···Cl intermolecular hydrogen bonding between the nitrogen N5 of amino group of the 4-nitroaniline and the Cl2 counterion and by weak C-H···π intermolecular interactions involving Cg pyrrole and phenyl rings (Table 1 and Fig. 2).

S2. Experimental
To a solution of [Co III (TPP)Cl] (100 mg, 0.141 mmol) (Madure & Scheidt, 1976) in dichloromethane (10 mL) was added an excess of 4-nitroaniline (80 mg, 0.579 mmol). The reaction mixture was stirred at room temperature and at the end of the reaction, the color of the solution changed from red-orange to dark-red. Crystals of the title complex were obtained by diffusion of hexanes through the dichloromethane solution.

S3. Refinement
All H atoms attached to C atoms were fixed geometrically and treated as riding with C-H = 0.99 Å (methylene) and 0.95 Å (aromatic) with U iso (H) = 1.2U eq (C aromatic , methylene ). The two H atoms of the amino group of the 4-nitroaniline axial ligand were found in the difference Fourier map and were refined independently with fixed isotropic displacement parameters.

Figure 1
An ORTEP view of the molecular structure of the title molecule with the atom-numbering. Displacement ellipsoids are drawn at 50%. The H atoms have been omitted for clarity.

Figure 2
The crystal structure of the title compound plotted in projection along [100]. H atoms have been omitted.
Special details Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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 > 2sigma(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.